Cyclopolymerization and Polymers with Chain-Ring Structures 9780841207318, 9780841209084, 0-8412-0731-3

Table of contents :
Title Page......Page 1
Half Title Page......Page 3
Copyright......Page 4
ACS Symposium Series......Page 5
FOREWORD......Page 6
Dedication......Page 7
PdftkEmptyString......Page 0
PREFACE......Page 10
Structure......Page 12
Biological Activity......Page 16
Narrow Molecular Weight Distribution Polymer......Page 17
Literature Cited......Page 19
Interaction across the space between reacting groups.......Page 21
Effect of a large substituent at the active chain end.......Page 26
Difference between intra- and intermolecular chain propagation reactions.......Page 27
Comparison between calculated differences ΔSc - ΔSp and experimental differences ΔS≠c - ΔS≠p.......Page 34
Literature cited......Page 37
3 Intramolecular Addition Modes in Radical Cyclopolymerization of Some Unconjugated Dienes......Page 39
Cyclopolymerization of Diallyl and Dimethallyl Dicarboxylates......Page 41
Cyclopolymerization of Allyl ∝-Substituted Acrylates......Page 44
Cyclopolymerization of Acrylic Anhydride......Page 45
Cyclopolymerization of Methacrylic Anhydride......Page 49
Literature Cited......Page 51
4 Styrene-Methyl Methacrylate Copolymers Derived from Styrene-Methacrylic Anhydride Copolymers......Page 53
Experimental......Page 55
Theoretical Aspects......Page 60
Results and Discussion......Page 63
Literature Cited......Page 69
5 N,N-Dimethyl-3,4-Dimethylenepyrrolidinium Bromide Polymer......Page 71
Cyclic Quaternary Ammonium Polymers......Page 72
Polymerization Studies of N,N-dimethyl-3,4-dimethylenepyrrolidinium Bromide......Page 75
Literature Cited......Page 81
6 Radical Cyclopolymerization of Divinyl Formal: Polymerization Conditions and Polymer Structure......Page 83
Experimental......Page 84
Results and Discussion......Page 86
Literature Cited......Page 92
7 Divinyl Ether-Maleic Anhydride Copolymer and Its Derivatives: Toxicity and Immunological and Endocytic Behavior......Page 93
Acute Toxicity of DIVEMA and two DIVEMA Derivatives......Page 94
Effects of DIVEMA and DIVEMA Derivatives on the Immune System.......Page 97
Endocytic Behaviour of DIVEMA and Derivatives......Page 103
Literature Cited......Page 105
8 Radical Polymerization of exo and endo N-Phenyl-5-norbornene-2,3-dicarboximides as Models for Addition-Curing Norbornene End-Capped Polyimides1......Page 107
Results and Discussion......Page 110
Literature Cited......Page 114
9 Cyclization Reaction of N-Substituted Dimethacrylamides in the Crystalline and Glassy States at 77 Κ......Page 116
Experimental......Page 118
Results and Discussion......Page 120
Conclusion......Page 128
Literature Cited......Page 130
10 Mössbauer Studies of Polymers from 1,1'-Divinylferrocene......Page 131
Results and Discussion......Page 133
Literature Cited......Page 144
11 New Phase Transfer Catalysts Containing Oxyethylene Oligomers......Page 146
Experimental......Page 147
Results and Discussion......Page 149
Literature Cited......Page 155
12 Synthesis of Macrocyclic Ring-Containing Polymers Via Cyclopolymerization and Cyclocopolymerization......Page 156
The Synthesis of 1,7-Dienes......Page 157
The Synthesis and Structural Determination of Model Compounds......Page 158
Cyclopolymerization of 1,7-Dienes......Page 160
Cyclopolymerization of 1,13-Dienes......Page 162
Cyclocopolymerization of 1,7-Dienes with Maleic Anhydride......Page 163
Cyclocopolymerization of a 1,13-Diene with MA......Page 166
Experimental......Page 167
Synthesis of Model Compounds......Page 169
Polymerization Studies......Page 170
Literature Cited......Page 172
13 Radiation-Induced Loss of Unsaturation in 1,2-Polybutadiene......Page 173
Experimental......Page 175
Results and Discussion......Page 177
Literature Cited......Page 182
14 C3 Cyclopolymerization: Cationic Cyclopolymerization of 1,3-Bis(p-vinylphenyl)propane and Its Derivatives......Page 183
Preparation of St-C3-St and its Derivatives......Page 184
Structure of Cyclopolymer from St-C3-St or VN-C3-VN......Page 185
Several Effects on the Cyclopolymerization......Page 189
Literature Cited......Page 199
15 Free Radical Polymerization of 2,5-Diphenyl-1,5-hexadiene1......Page 202
Experimental......Page 203
Results and discussion......Page 204
Literature cited......Page 210
16 Synthesis and Cationic Polymerization of 1,4-Dimethylenecyclohexane......Page 212
Polymerization Studies......Page 213
Polymer Characterization......Page 214
Discussion......Page 218
Experimental......Page 223
Literature Cited......Page 225
17 Acetylene-Terminated Fluorocarbon Ether Bibenzoxazole Oligomers......Page 227
Results and Discussion......Page 228
Experimental......Page 235
Literature Cited......Page 239
18 Initiation of an Acetylene-Terminated Phenyl Quinoxaline......Page 240
Influence of Initiator Concentration......Page 241
Residual Exotherm......Page 243
Literature Cited......Page 246
19 Fracture Behavior of an Acetylene-Terminated Polyimide......Page 247
Fracture Testing......Page 248
Literature Cited......Page 254
20 Synthesis and Characteristics of Poly(bisdichloromaleimides)1......Page 255
Experimental......Page 257
Results and Discussion......Page 258
Literature Cited......Page 273
21 Thermally Stable Polyimides from Pyrrole Dicarboxylic Acid Anhydride Monomers......Page 274
Discussion......Page 276
Literature Cited......Page 285
Processable Aromatic Nitrile-Modified Imide Precursors......Page 286
Cyclopolymerization or Polycyclotrimerization......Page 287
TSTR Polyimides with Ring-Chain Structures......Page 288
Experimental......Page 292
Results and Discussion......Page 293
Conclusion......Page 295
Literature Cited......Page 296
23 Heat and Water Resistant Polyphenyl-as-triazines from Terephthalamidrazone......Page 297
Experimental......Page 299
Results and Discussion......Page 302
Literature Cited......Page 309
24 Polycocyclotrimerization of Isocyanates......Page 310
Experimental......Page 311
Characterization of Polycocyclotrimers......Page 312
Results and Discussion......Page 313
Literature Cited......Page 322
25 Polymerization of Bisphthalonitriles: Metal Free Phthalocyanine Formation......Page 324
Discussion and Results......Page 325
Experimental......Page 331
References......Page 334
26 Characterization of the Cure of Diether-Linked Phthalonitrile Resins......Page 335
Experimental......Page 336
Results and Discussion......Page 338
Literature Cited......Page 347
27 Polyamides Via the Phosphorylation Reaction: Poly-p-benzamide (PBA) and N-Methyl PBA Copolymers......Page 349
Discussion and Results......Page 352
Experimental......Page 359
Literature Cited......Page 360
28 Polymers and Fibers of para- and meta-Phenylene Oxadiazole-N-Methyl Hydrazide Copolymers: High Strength-High Modulus Materials of Increased Molecular Flexibility......Page 361
Acknowledgment......Page 366
Literature Cited......Page 367
29 Free Radical Copolymerization of 4,7-Dihydro-1,3-dioxepins with Maleic Anhydride and Maleimides: Preparation of Head-to-Head Poly(4-hydroxycrotonic acid) and Poly(γ-crotonolactone)......Page 368
Literature Cited......Page 386
30 Synthesis of Polyspiroketals Containing Five-, Six-, Seven-, and Eight-Membered Rings......Page 388
Experimental......Page 395
Literature Cited......Page 399
31 Hydrogen Bonding Ring Containing Polymers: Poly(enamine-Ketones)......Page 400
EXPERIMENTAL......Page 401
Monomeric Models......Page 403
Poly(enamine-ketones)......Page 406
Literature Cited......Page 412
32 Cyclopolymerization of Carbon Suboxide: Mechanism and Polymer Properties......Page 414
Experimental......Page 415
Results and Discussion......Page 418
Polymerization......Page 431
Conclusions......Page 434
Literature Cited......Page 435
B......Page 437
C......Page 438
D......Page 440
H......Page 442
K......Page 443
M......Page 444
P......Page 445
S......Page 447
Z......Page 448

Citation preview

Cyclopolymerization and Polymers with Chain-Ring Structures

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

Cyclopolymerization and Polymers with Chain-Ring Structures George B. Butler,

EDITOR

University

Jiri E. Kresta,

EDITOR

University of Detroit

Based on a symposium cosponsored by the Divisions of Polymer Chemistry and Organic Coatings and Plastics Chemistry at the 181st ACS National Meeting, Atlanta, Georgia, March 30-April 1, 1981.

ACS

SYMPOSIUM AMERICAN

CHEMICAL

WASHINGTON, D. C.

SERIES

195

SOCIETY 1982

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

Library of Congress Cataloging in Publication Data

Cyclopolymerization and polymers with chain-ring structures. (ACS symposium series, ISSN 0097-6156; 195) Includes bibliographies and index 1. Polymers and polymerization—Congresses Cyclic compounds—Congresses I. Butler, George B., 1916 . II. Kresta, Jiri E., 1934- . III. American Chemical Society. Division of Polymer Chemistry. IV. American Chemical Society. Division of Organic Coatings and Plastics Chemistry. V. Series. QD380.C9 1982 547.7 82-11331 ISBN 0-8412-0731-3 ACSMC8 195 1-459 1982

Copyright © 1982 American Chemical Society All Rights Reserved. The appearance of the code at the bottom of the first page of each article in this volume indicates the copyright owner's consent that reprographic copies of the article may be made for personal or internal use or for the personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay the stated per copy fee through the Copyright Clearance Center, Inc. for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to copying or transmission by any means—graphic or electronic—for any other purpose, such as for general distribution, for advertising or promotional purposes, for creating new collective work, for resale, or for information storage and retrieval systems. The copying fee for each chapter is indicated in the code at the bottom of the first page of the chapter. The citation of trade names and/or names of manufacturers in this publication is not to be construed as an endorsement or as approval by ACS of the commercial products or services referenced herein; nor should the mere reference herein to any drawing, specification, chemical process, or other data be regarded as a license or as a conveyance of any right or permission, to the holder, reader, or any other person or corporation, to manufacture, reproduce, use, or sell any patented invention or copyrighted work that may in any way be related thereto. PRINTED IN THE UNITED STATES OF AMERICA

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

ACS Symposium Series Μ. Joa

Advisory Board David L. Allara

Marvin Margoshes

Robert Baker

Robert Ory

Donald D. Dollberg

Leon Petrakis

Robert E. Feeney

Theodore Provder

Brian M. Harney

Charles N. Satterfield

W.

Dennis Schuetzle

Jeffrey Howe

James D. Idol, Jr.

Davis L. Temple, Jr.

Herbert D. Kaesz

Gunter Zweig

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

FOREWORD The ACS S Y M P O S I U M S E R I E S was founded in 1974 to provide a medium for publishing symposia quickly in book form. The format of the Series parallels that of the continuing A D V A N C E S I N C H E M I S T R Y S E R I E S except that in order to save time the papers are not typeset but are reproduced as they are submitted by the authors in camera-ready form. Papers are reviewed under the supervision of the Editors with the assistance of the Series Advisory Board and are selected to maintain the integrity of the symposia; however, verbatim reproductions of previously published papers are not accepted. Both reviews and reports of research are acceptable since symposia may embrace both types of presentation.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

This book is dedicate a pioneer of cyclopolymerization chemistry, on the anniversary of his 65th birthday.

vii

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

viii

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

was born in Liberty, Mississippi, in April 1916. He studied at Mississippi College, Mississippi (B.A. 1938), and at the University of North Carolina at Chapel Hill (Ph.D. 1942). In 1946, after working briefly at the Rohm and Haas Co., he joined the faculty of the Chemistry Department at the University of Florida as an instructor. He was promote professor in 1951 and t career, over 80 students have obtained advanced degrees under his guidance, and he has published hundreds of scientific papers. His research contributions to polymer chemistry span many areas, from studies of alternating copolymers of maleic anhydride and vinyl ether ("pyran copolymer") having interferon inducing capability and antitumor activity, to polymerization of triazoline diones and synthesis of the antiaromatic 3,3-dimethoxycyclopropene. His best known contribution to polymer science is the discovery of the cyclopolymerization reaction in 1956, during the study of free radical polymerization of divinyl monomers. For this pioneering work he was awarded the 1980 American Chemical Society Witco Award for Polymer Chemistry. Among other awards, he also received the Florida Section ACS Award in 1963, and the Herty Award from the Georgia Section of the ACS in 1978. Besides his research work, he is an organizer and co-editor of ReGEORGE

BERGEN

BUTLER

views in Macromolecular

Chemistry and

the Journal of

Macromolecular

Science—Reviews.

He also serves on the editorial boards of the Journal

of Macromolecular

Science—Chemistry,

Polymer Science, and

Macromolecular

Macromolecules,

the Journal

of

Synthesis.

On the occasion of his 65th birthday, the contributors to this book wish Professor Butler many productive years in his future research activities in polymer chemistry.

ix

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

PREFACE C^YCLOPOLYMERIZATION HAS B E E N DEFINED

as a chain-growth polymerization reaction of l,X-bis-(multiple bonded) monomers which introduces cyclic structures into the main chain of the resulting polymers. However, polymers containing cyclic units in the main chain can be synthesized by a wide variety of methods upon which this book is based decided to broaden its scope to include both polymers formed by cyclopolymerization and polymers containing chain-ring structures. Although cyclopolymerization has been extensively investigated, because of its complexity and the variety of monomers capable of participating in this mode of chain propagation, considerable research emphasis continues in this area. The microstructure of cyclopolymers studied by modern spectroscopic techniques, particularly C NMR, has yielded significant results. Aspects not totally understood and which continue to be investigated include ring size, theoretical interpretations of the driving force for control of ring size, the relative importance of kinetic versus thermodynamic control, electronic interactions, steric effects, macrocyclic polymers, and charge-transfer complexes in cyclocopolymerization. This volume includes 16 papers dealing with the various aspects of cyclopolymers and cyclopolymerization. 13

Sixteen papers dealing with polymers containing chain-ring structures are also included. During an extended period in which considerable emphasis was placed on development of thermally stable polymers, a wide variety of synthetic methods have been developed, and numerous polymers having interesting and occasionally superior properties have been reported. Among these reactions are the novel cross-linking or chain extension trimerization reactions of various end groups, and a variety of condensation reactions leading to heterocyclic structures in the main polymer chain.

xv

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

The editors believe that the scientific community willfindthis book helpful as a source of advances and developments in the area of cyclopolymerization, and the preparation and properties of polymers with chain-ring structures. GEORGE B. BUTLER

University of Florida Gainesville, FL JIRI E . KRESTA

University of Detroit Detroit, MI

xvi

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

1 Biologically Active Synthetic Anionic Polymers DAVID S. BRESLOW Hercules Research Center, Wilmington, D E 19899

Maleic anhydride and vinyl ether undergo a cyclic alternatin copolymerizatio i 2:1 ratio. 13 a mixture o tetrahydrofura tetrahydropyra rings in an approximately 0.8:1 ratio. The copolymer shows a remarkable variety of biological activities. It is an antitumor agent; i t induces the formation of interferon; i t has antiviral, antibacterial, and antifungal activity; i t is an anticoagulant and an anti-inflammatory agent; and it aids in the removal of plutonium from the liver. The copolymer is an immunostimulant, and appears to act by stimulating macrophages. A study of the effect of molecular weight and molecular weight distribution on toxicity and biological activity has led to the synthesis of an active copolymer with low toxicity, which is being investigated clinically as an antitumor agent. C

Maleic anhydride and vinyl ether undergo a radical-catalyzed cyclic alternating copolymerization in a 2:1 ratio. This copolymer, frequently designated in the literature as DIVEMA or as pyran copolymer, has shown unusual and exciting biological activity, and has therefore undergone intensive investigation. Structure The 2:1 copolymer, first reported in 1958 (1), was assumed to have the tetrahydropyran structure, I in Scheme 1 (2). Although this structure had been widely accepted (3), there was no convincing evidence for i t . In fact, a number of reports in the literature suggested that the kinetically controlled route leading to a tetrahydrofuran ring, II in Scheme 1, would be more likely. Thus, i t was shown by ESR that the 5-hexenyl radical, formed by photolysis of 6-heptenoyl peroxide, cyclizes 0097-6156/82/0195-0001 $06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

2

POLYMERS WITH CHAIN-RING

STRUCTURES

LU LU Χ Ο CO

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

1.

BRESLOW

Biologically Active Synthetic Anionic Polymers

e x c l u s i v e l y t o the cyclopentylmethylene r a d i c a l ( 4 ) , whereas hexenyl r a d i c a l s s t a b i l i z e d by carbonyl or n i t r i l e groups c y c l i z e to cyclopentane and/or cyclohexane d e r i v a t i v e s , depending on the s u b s t i t u t i o n pattern ( 5 ) . S i m i l a r l y , m e t h y l d i a l l y l a m i n e undergoes c y c l o p o l y m e r i z a t i o n e x c l u s i v e l y t o form a polymeric p y r r o l i d i n e , whereas methyl-substituted d e r i v a t i v e s give polymers c o n t a i n i n g both f i v e - and six-merabered rings (6). Since i t was q u i t e apparent from the l i t e r a t u r e that the s t r u c t u r e o f the maleic a n h y d r i d e - v i n y l ether copolymer could not be p r e d i c t e d , we s e t out to determine the s t r u c t u r e by l ^ C NMR, using model compounds to a i d i n a s s i g n i n g the resonances ( 7 ) . F i g u r e 1 shows the l^C NMR spectrum o f the polymer, prepared i n benzene with carbon t e t r a c h l o r i d e as a c h a i n t r a n s f e r agent, a f t e r h y d r o l y s i s e t s o f peaks, l a b e l e d A-H decoupling experiment, i t was p o s s i b l e to show that peaks A and Β are t r i p l e t s due to methylene carbons, peaks C-F are doublets due to methine carbons, and peaks G and H are due to carbonyls· D e f i n i t i v e assignments were made by comparison with the spectra of the model compounds. 2,6-Dimethyltetrahydropyran-3,4d i c a r b o x y l i c a c i d was prepared, as shown i n Scheme 2, as the six-membered r i n g model; only one isomer, i d e n t i f i e d as a l l - t r a n s by proton NMR, was i s o l a t e d .

Scheme 2 2,5-Dimethyltetrahydrofuran-3,4-dicarboxylic a c i d was prepared, as shown i n Scheme 3, as the five-membered r i n g model; three isomers were i s o l a t e d , but the stereochemistry could not be assigned u n e q u i v o c a l l y . Inspection o f the NMR s p e c t r a o f the model compounds, plus that of commercially a v a i l a b l e

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

3

4

POLYMERS WITH CHAIN-RING

STRUCTURES

Ο m

Q •S

I b

•5

>

I

1

! •δ-

Ι CO

I

I

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

1.

BRESLOW

Biologically Active Synthetic Anionic Polymers

5

Scheme 3 d i m e t h y l s u c c i n i c a c i d (mes plu racemic) showed onl unique carbon atom, at 34. internal reference), assignabl methylen tetrahydropyran r i n g . T h i s corresponds to peak Β i n the polymer spectrum. However, peak areas (from suppressed Ν0Ε experiments) showed that the polymer could not c o n s i s t s o l e l y of t e t r a ­ hydropyran r i n g s ; c a l c u l a t i o n s show the r a t i o o f f i v e - t o six-membered rings to be approximately 0.8 to 1. We f e e l there i s i n s u f f i c i e n t evidence a t the present time t o make d e f i n i t e assignments of stereochemistry to the polymer Ο ) · Kunitake and Tsukino (8) a l s o used l^C NMR to determine r i n g s i z e i n the copolymer, but they c a l c u l a t e d chemical s h i f t s by e x t r a p o l a t i n g published data on simpler c y c l i c compounds. By t h i s method they concluded that a copolymer prepared i n c h l o r o ­ form contained only t e t r a h y d r o f u r a n r i n g s . However, t h e i r published spectrum of the copolymer contained the same peak Β as ours, and t h e r e f o r e the copolymer must c o n s i s t o f both f i v e - and six-membered r i n g s . The spectrum of a copolymer prepared i n acetone-carbon d i s u l f i d e was too p o o r l y resolved t o show peak B, but Kunitake and Tsukino estimated the polymer to c o n t a i n about 90% tetrahydropyran r i n g s . Biological Activity The 2:1 maleic a n h y d r i d e - v i n y l ether copolymer shows a b e w i l d e r i n g v a r i e t y o f b i o l o g i c a l a c t i v i t i e s (9). I t was f i r s t shown to have antitumor a c t i v i t y against a number o f s o l i d tumors (10). I t induces the formation o f i n t e r f e r o n ( V I ) , and therefore shows a n t i v i r a l a c t i v i t y . I t has been shown t o be a c t i v e a g a i n s t over 20 v i r u s e s , i n c l u d i n g a number o f cancerinducing v i r u s e s and herpes simplex (2.*1I)· Qui surprisingly, i t has a l s o been shown t o have a n t i b a c t e r i a l a c t i v i t y a g a i n s t both gram-positive and gram-negative organisms (JL3). I t a l s o shows a n t i f u n g a l a c t i v i t y (14) and acts as an a n t i c o a g u l a n t (_15). I t i n h i b i t s adjuvant d i s e a s e i n r a t s (16), a syndrome b e l i e v e d to be r e l a t e d t o rheumatoid a r t h r i t i s i n humans. In conjunction with c e r t a i n c h e l a t i n g agents, i t has been shown to be a c t i v e i n removing polymeric plutonium from the l i v e r (17). t e

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

6

POLYMERS

WITH

CHAIN-RING

STRUCTURES

T h i s broad spectrum of a c t i v i t y q u i t e o b v i o u s l y l e d to considerable a c t i v i t y by b i o l o g i s t s and p h y s i c i a n s to e x p l a i n the polymer's mode of a c t i o n . One of the f i r s t d i s c o v e r i e s showed t h a t , under c e r t a i n c o n d i t i o n s , i t g r e a t l y a c c e l e r a t e d the r a t e of phagocytosis, i . e . , the rate of removal of f o r e i g n bodies from the blood stream (18). Quite s u r p r i s i n g l y , i t showed the same a c t i v i t y i n immunosuppressed mice as i n normal mice (19). I t was shown to i n h i b i t reverse t r a n s c r i p t a s e i n b i r d s , r e p t i l e s , and mammals (20). A c o n s i d e r a b l e amount of work i n a number of l a b o r a t o r i e s f i n a l l y reached the c o n c l u s i o n that the major mode of a c t i o n i n v o l v e s the a c t i v a t i o n of macrophages (21, 22), l a r g e white blood c e l l s which have the f u n c t i o n of removing f o r e i g n bodies from the blood stream. T h i s hypothesis i s g e n e r a l l y accepted, but by no means proven (9)· Narrow Molecular Weigh The i n i t i a l polymer i n v e s t i g a t e d was prepared u s i n g benzoyl peroxide i n a nonsolvent f o r the polymer, and the polymeri z a t i o n was c a r r i e d to a very high conversion. As a r e s u l t , the polymer had a very broad molecular weight d i s t r i b u t i o n . This polymer underwent Phase I c l i n i c a l e v a l u a t i o n as a chemotherapeutic agent against cancer. U n f o r t u n a t e l y , i t showed a number of u n d e s i r a b l e s i d e e f f e c t s (23), and i t was decided i n t h i s l a b o r a t o r y to see i f we could decrease the t o x i c i t y without l o s i n g the antitumor a c t i v i t y . Degradation of the polymer showed that decreasing the molecular weight d i d indeed decrease the t o x i c i t y of the polymer (24). However, before going f u r t h e r we had to develop a means f o r c h a r a c t e r i z i n g the polymer. T h i s was done by c o n v e r t i n g i t to i t s methyl e s t e r and running s i z e e x c l u s i o n chromatography (SEC) on a p r e p a r a t i v e s c a l e . These f r a c t i o n s , which had reasonably narrow molecular weight d i s t r i b u t i o n s on an a n a l y t i c a l instrument, were then compared with polystyrene standards and shown to f i t the u n i v e r s a l c a l i b r a t i o n curve i n the usual f a s h i o n . In order to o b t a i n s u f f i c i e n t l y l a r g e q u a n t i t i e s of polymer f o r both c h a r a c t e r i z a t i o n and b i o l o g i c a l e v a l u a t i o n , a s o l u t i o n p o l y m e r i z a t i o n with l i m i t e d conversion was devised; a comparison of the two polymers by SEC i s shown i n Figure 2; the o r i g i n a l polymer i s NSC 46015 and the new polymer MVE-2. B i o l o g i c a l t e s t i n g showed that t h i s new polymer d i d indeed have low t o x i c i t y and maintained i t s antitumor a c t i v i t y (24). Meanwhile, however, research done at the N a t i o n a l Cancer I n s t i t u t e , as w e l l as a t other l a b o r a t o r i e s , demonstrated that the most d e s i r a b l e way of using t h i s m a t e r i a l was as an immunoadjuvant i n c o n j u n c t i o n with other treatments (25, 26). The goal i s to reduce the tumor burden by some means - surgery, r a d i a t i o n , chemotherapy - and

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

B RE SLOW

1.

Biologically Active Synthetic Anionic Polymers

7

ο

M.W. h i '

10

7

1

1

I m ι! ι 4 ι

106

liuthi

10

5

1

linil 11 ι

10*

IJIUU
Μ ΓΤ

=

M

r

where k and k a r e the r a t e c o n s t a n t s o f the i n t r a m o ­ l e c u l a r and t h e i n t e r m o l e c u l a and [iij i s the monomer molar c o n c e n t r a t i o n . The f a c t o r 2 depends on the presence o f two p o i n t s o f a t t a c k , the two u n s a t u r a t i o n s , o f Γ· r a d i c a l s onto the monomer mo­ lecule. Assuming t h a t the polymer i s comprised o n l y of c y c l i c and u n s a t u r a t e d s t r u c t u r a l u n i t s , f + f = 1 , and l e t t i n g r = k / k o b t a i n s from eq. ( (5) has been found t o f i t s a t i s f a c t o r i l y the e x p e r i m e n t a l d a t a , i n the c a s e s i n which the composit i o n o f c y c i o p o l y m e r s o b t a i n e d from s y m m e t r i c a l d i e n e s has been i n v e s t i g a t e d as a f u n c t i o n o f the monomer c o n c e n t r a t i o n (^-7)· F o c u s s i n g a t t e n t i o n on the parameter r , which w i l l be c a l l e d " c y c l i z a t i o n r a t i o " , one c a n see t h a t i t i s the double bond c o n c e n t r a t i o n ( e q u a l t o t w i c e the monomer c o n c e n t r a t i o n ) a t which f = f = 0.5 . In o t h e r words, i n the polymer o b t a i n e d from a s o l u t i o n i n which twice the monomer c o n c e n t r a t i o n i s e q u a l to r , t h e s t r u c t u r a l u n i t s a r e 50 * / < > c y c l i c and 50 °/o u n s a t u r a t e d : i n the c o m p e t i t i o n between i n t r a - and i n t e r m o l e c u l a r c h a i n p r o p a g a t i o n t h e r e i s no winner. I t might be o f i n t e r e s t , t h e r e f o r e , t o take i n t o cons i d e r a t i o n some e x p e r i m e n t a l v a l u e s o f r . In T a b l e I some o f these v a l u e s have been c o l l e c c

c

c

u

c

c

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

2.

GUAiTA

Temperature Dependence of Cyclization Ratios

Table I - C y c l i z a t i o n r a t i o s i n f r e e r a d i c a l lymerizations.

monomer

a c r y l i c anhydride m e t h a c r y l i c anhydride d i p h e n y i h e x a d i ene

polymerization temperature (°C) 70 60 70

15

cyclopo-

r

c (mol/i)

Ref.

9.79 97.32 8.70

(4) (8) (£)

t e d . One c a n see t h a t they a r e v e r y h i g h , i n d i c a t i n g t h a t even i n t h e polymer nomers t h e c y c l i c s t r u c t u r a l i n e a r ones. On t h e o t h e r hand, B u t l e r and Raymond (10) c a l c u l a t e d the p r o b a b i l i t i e s of being i n the neighbourhood o f t h e r e a c t i o n s i t e f o r t h e double bond pendant from t h e r e a c t i v e c h a i n end, and f o r a double bond o f an u n r e a c t e d m o l e c u l e , and found t h a t , from a p u r e l y s t a t i s t i c a l p o i n t o f view, o n l y a t a monomer c o n c e n t r a t i o n as low a s 1 o r 2 m o l / i s h o u l d t h e double bond pendant from t h e a c t i v e c h a i n end have a g r e a t e r o p p o r t u n i t y t o meet t h e a c t i v e s i t e than any o t h e r double bond i n the s o l u t i o n . T h e r e f o r e , t h e h i g h v a l u e s o f t h e c y c l i z a t i o n r a t i o s mean t h a t , i n c o n c e n t r a t e d s o l u t i o n s , the a c t i v e c h a i n end c a n d i s t i n g u i s h t h a t one o f t h e many double bonds around i t i s u n i q u e and, o f c o u r s e , t h a t t h e r e a c t i o n o f t h e a c t i v e end w i t h t h i s u n i q u e double bond i s e a s i e r than w i t h any o t h e r double bond. Of t h e i d e a s which have been p u t f o r w a r d t o i n t e r p r e t such a s i t u a t i o n , i t seems r e a s o n a b l e n o t t o g i v e much importance t o t h e p o s s i b i l i t y t h a t an i n d u c t i v e e f f e c t would be o p e r a t i v e a t a p o s i t i o n t h r e e o r f o u r atoms removed from t h e r e a c t i o n s i t e : i f such an e f f e c t would e x i s t , i t would be v e r y weak, and would n o t j u s t i f y such a d r a m a t i c i n c r e a s e o f t h e r e a c t i v i t y of t h e pendant double bond, as i s p a r t i c u l a r l y e v i d e n t i n t h e case o f m e t h a c r y l i c a n h y d r i d e , b u t a l s o i n t h e c a s e s o f t h e o t h e r monomers. Another, more r e a l i s t i c , p o s s i b i l i t y would be t h e a n a l o g o f what i t has been a l r e a d y s a i d f o r t h e monomer m o l e c u l e s : an i n t e r a c t i o n a c r o s s t h e space between t h e r e a c t i o n s i t e and the pendant double bond (1_), a s i s

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS

16 schematically

represented

WITH

CHAIN-RING

STRUCTURES

here:

Without e n t e r i n g i n t o d e t a i l s of the n a t u r e of such an i n t e r a c t i o n , i t seems p o s s i b l e to argue t h a t , i f the i n t e r a c t i o n can e x i s t , i t can e x i s t as w e l l between the r e a c t i o n s i t e and one double bond of an u n r e a c t e d molec u l e , as i s shown i n the f o l l o w i n g scheme:

Thus, an i n t e r a c t i o n a c r o s s the space might r e p r e s e n t a p o s s i b l e r e a c t i o n p a t h , but i t would n o t e x p l a i n , a l o n e , the p r e f e r e n t i a l a d d i t i o n of the a c t i v e c h a i n end on the pendant double bond. Effect

o f a l a r g e s u b s t i t u e n t a t the a c t i v e c h a i n

end.

A q u i t e d i f f e r e n t i d e a has been s u g g e s t e d by Gibbs and B a r t o n (JJ_) t o j u s t i f y the predominance of i n t r a m o l e c u l a r c y c l i z a t i o n s : on the b a s i s of l i t e r a t u r e d a t a (1_2,J^) r e g a r d i n g the r a t e c o n s t a n t s f o r c h a i n p r o p a g a t i o n and t e r m i n a t i o n i n the f r e e r a d i c a l p o l y m e r i z a t i o n of m e t h y l a e r y l a t e and b u t y l a e r y l a t e , and p a r t i c u l a r l y g i v i n g much importance t o the l a r g e d i f f e r e n c e i n the v a l u e s of k and as r e p o r t e d by Matheson (12) f o r m e t h y l a c r y l a t e and by M e l v i l l e and B i c k e l (11^) f o r b u t y l a c r y l a t e , Gibbs and B a r t o n (YV) p o s t u l a t e d t h a t the p r e s e n c e of a l a r g e s u b s t i t u e n t a t the a c t i v e c h a i n end i n the c y c l o p o l y m e r i z a t i o n o f u n c o n j u g a t e d d i e n e s might h i n d e r the a p p r o a c h of u n r e a c t e d m o l e c u l e . The main drawback of t h i s p o i n t of view l i e s i n the u n c e r t a i n t y of the v a l u e s of the r a t e c o n s t a n t s r e l a t i v e t o b u t y l a c r y l a t e . As one can see i n T a b l e I I , the c o n s t a n t s c a l c u l a t e d from the d a t a of Bagdasaryan p

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

2.

GUAiTA

Temperature Dependence of Cyclization Ratios

17

T a b l e I I - Rate c o n s t a n t s i n f r e e r a d i c a l p o l y m e r i z a t i o n s a t 30°C. monomer

k

k

Ρ methyl a c r y l a t e methyl a c r y l a t e butyl acrylate butyl acrylate

720 590 14 570

Ref.

t

2 . 2 •10 3.6 •10 1.8 .104 8.3 •10 6

(12) (14) (11) (15)

6

6

(14) f o r m e t h y l a c r y l a t e do n o t g r e a t l y d i f f e r from those o f Matheson (V2); c a l c u l a t e d f o r b u t y l a c r y l a t e a c c o r d i n g t o Bengough and M e l v i l l e (Jj>) a r e s e v e r a l t i m e s h i g h e r t h a n t h o s e c a l c u l a t e d a c c o r d i n g t o M e l v i l l e and B i c k e l (Jji,). I t i s q u i t e o b v i o u s t h a t , i f the M e l v i l l e - B e n g o u g h c o n ­ s t a n t s a r e c o r r e c t , t h e l a r g e d i f f e r e n c e between t h e v a l u e s o f t h e c o n s t a n t s r e l a t i v e t o m e t h y l and b u t y l a c r y l a t e s d i s a p p e a r s , and t h e h y p o t h e s i s o f Gibbs and Barton loses i t s experimental support. I t i s of i n t e ­ r e s t t o note that the Bengough-Melville k value agre­ es, whereas t h a t o f M e l v i l l e - B i c k e l does n o t , w i t h t h e c a l c u l a t e d p r e - e x p o n e n t i a l f a c t o r o f t h e c o n s t a n t k^, and t h i s might be t a k e n as an e v i d e n c e , though i n d i r e c t of t h e g r e a t e r r e l i a b i l i t y o f t h e B e n g o u g h - M e l v i l l e result. p

D i f f e r e n c e between i n t r a - and i n t e r m o l e c u l a r pagation reactions.

chain

pro­

The h y p o t h e s e s c o n s i d e r e d so f a r share t h e attempt o f e x p l a i n i n g t h e ease o f f o r m a t i o n of the r i n g s t r u c t u ­ res i n c y c l o p o l y m e r i z a t i o n t a k i n g i n t o account only the r e l a t i v e a b i l i t y o f t h e double bond pendant from the a c t i v e c h a i n end, and o f t h e double bonds o f an u n r e a c t e d monomer m o l e c u l e , t o r e a c h t h e r e a c t i o n s i t e . No a t t e n t i o n i s p a i d t o t h e f a c t t h a t t h e i n t r a m o l e c u ­ l a r and i n t e r m o l e c u l a r c h a i n p r o p a g a t i o n r e a c t i o n s a r e b a s i c a l l y d i f f e r e n t , i n t h e sense t h a t t h e f o r m e r i n ­ v o l v e s an e n t r o p y d e c r e a s e due t o t h e l o s s o f some r o ­ t a t i o n a l degrees o f freedom a t t h e end o f t h e a c t i v e c h a i n , whereas t h e l a t t e r i n v o l v e s an e n t r o p y d e c r e a s e

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

18

POLYMERS

WITH

CHAIN-RING

STRUCTURES

depending on the f a c t t h a t two independent m o l e c u l a r e n t i t i e s become " f u s e d " t o g e t h e r . The q u e s t i o n t o be answered i s : which o f the two e n t r o p y d e c r e a s e s i s t h e largest? To be a b l e t o answer t h i s q u e s t i o n i s v e r y i n t e ­ r e s t i n g because f o r the r e a c t i o n s c o n s i d e r e d , which can be s c h e m a t i c a l l y r e p r e s e n t e d as f o l l o w s :

"Ό—Ό^Ο (Ρ·)

(activate

(P · )

( a c t i v a t e d complex)

(Ρ'·)

one might t e n t a t i v e l y assume t h a t the e n t r o p i e s o f the r e a c t i o n p r o d u c t s a r e c l o s e t o the e n t r o p i e s o f t h e a c t i v a t e d complexes. I n o t h e r words, t h e e n t r o p y chan­ ge A S o c c u r r i n g i n t h e c y c l i z a t i o n s h o u l d be a p p r o ­ x i m a t e l y e q u a l t o the a c t i v a t i o n e n t r o p y ASç o f t h e reaction: C

AS

=

C

SQ. -

S

P

. *

S

a C f C

-

S

P

.=

AS*

where 3 ρ , S Q . and S a r e t h e molar e n t r o p i e s o f Ρ· and Q» r a d i c a l s and o f t h e a c t i v a t e d complex, r e s p e c ­ t i v e l y . S i m i l a r l y , f o r the i n t e r m o l e c u l a r propagation reaction: β

AS

=

p

a c

S

p t #

-

c

Sp, ~

S

a C f P

-

Sp. =

AS*

where Spt i s the molar e n t r o p y o f the growing r a d i c a l , i n c r e a s e d by one monomeric u n i t w i t h r e s p e c t t o Ρ · , and ^ac,ρ olar e n t r o p y o f t h e a c t i v a t e d complex o f t h i s r e a c t i o n . T h e r e f o r e , i f one i s a b l e t o e v a l u a t e AS and ASp, an e s t i m a t e o f t h e c o r r e s p o n d i n g a c t i ­ v a t i o n e n t r o p i e s becomes p o s s i b l e . #

i

s

m

C

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

2.

GUAiTA

Temperature Dependence of Cyclization Ratios

19

An e x p e r i m e n t a l e v a l u a t i o n o f t h e d i f f e r e n c e b e tween t h e a c t i v a t i o n e n t r o p i e s i s o b t a i n e d , i n p r i n c i p l e , from t h e i n v e s t i g a t i o n o f t h e temperature dependence o f t h e c y c l i z a t i o n r a t i o r , which c a n be exp r e s s e d i n t h e form: c

r

c

By p l o t t i n g I n r as a f u n c t i o n o f 1/T a s t r a i g h t l i ne s h o u l d be o b t a i n e d , and t h e d i f f e r e n c e between t h e a c t i v a t i o n e n t r o p i e s s h o u l d be g i v e n by t h e i n t e r c e p t . The problem i s t h a t , as i t i s w e l l known, e s p e c i a l l y when one c o n s i d e r s r e a c t i o phases, i t i s d i f f i c u l t r u e a c t i v a t i o n e n t r o p i e s and e n e r g i e s , o r a p p a r e n t a c t i v a t i o n q u a n t i t i e s . I n o t h e r words, q u i t e f r e q u e n t l y one does n o t know i f t h e c o n s t a n t s b e i n g t r e a t e d are pure, s i n g l e , r a t e c o n s t a n t s , r a t h e r t h a t a combin a t i o n o f s e v e r a l r a t e c o n s t a n t s . Of c o u r s e , t h e a g r e ement between t h e e x p e r i m e n t a l d i f f e r e n c e between t h e a c t i v a t i o n e n t r o p i e s f o r i n t r a - and i n t e r m o l e c u l a r c h a i n p r o p a g a t i o n , and t h e c a l c u l a t e d d i f f e r e n c e b e tween the e n t r o p y d e c r e a s e s o c c u r r i n g i n t h e same r e a c t i o n s , c a n be taken as an i n d i c a t i o n o f t h e r e l i a b i l i t y o f b o t h t h e e x p e r i m e n t a l and t h e c a l c u l a t e d v a lues. c

The e n t r o p y changes o c c u r r i n g i n i n t r a . - and i n t e r m o l e c u l a r c h a i n p r o p a g a t i o n r e a c t i o n s c a n be e a s i l y c a l c u l a t e d i f some more o r l e s s d r a s t i c assumptions are made. F i r s t o f a i l , i t i s w e l l known t h a t , from an e x p e r i m e n t a l p o i n t o f view, f r e e r a d i c a l p o l y m e r i z a t i o n s seem s c a r c e l y i n f l u e n c e d by t h e e n v i r o n m e n t a l c o n d i t i o n s , and p r a c t i c a l l y o c c u r w i t h t h e same r a t e i n s o l v a t i n g and n o n - s o i v a t i n g , o r i n p o l a r and nonpol a r media. T h i s suggests t h a t the f r e e energy change a s s o c i a t e d w i t h a g i v e n s t e p o f t h e growth of t h e p o l y mer c h a i n does n o t s i g n i f i c a n t l y depend on t h e a c t u a l v a l u e o f t h e f r e e energy o f the d i f f e r e n t s p e c i e s i n v o l v e d . I t might then be a c c e p t e d t h a t t h e r a t e o f t h e propagation r e a c t i o n s , e i t h e r i n t r a - or intermolecular, would be s i m i l a r i n s o l u t i o n , as w e l l as i n a h y p o t h e -

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

20

POLYMERS

WITH CHAIN-RING STRUCTURES

t i c a l i d e a l gas s t a t e . The r e a s o n f o r such an assump­ t i o n i s t h a t the e a v a i u a t i o n o f the e n t r o p y of the r e a c t a n t s and of the r e a c t i o n p r o d u c t s can be c a r r i e d out more e a s i l y i f they a r e c o n s i d e r e d i n the i d e a l gas s t a t e . I t i s w e l l known t h a t e n t r o p y , and i n g e n e r a l the thermodynamic p r o p e r t i e s , of a g i v e n m o l e c u l e can be b u i l t up as the sum of d e f i n i t e c o n t r i b u t i o n s which can be a s s i g n e d t o the v a r i o u s groups p r e s e n t i n the m o l e c u l e . As an example, c o n s i d e r the m o l e c u l e o f bu­ tane, made of two m e t h y l and two methylene g r o u p s : each methyl group c o n t r i b u t e s t o the molar e n t r o p y i n the i d e a l gas s t a t methylene group c o n t r i b u t e Summing up, and s u b t r a c t i n g the term Rin2 (being 2 the symmetry number of t h i s m o l e c u l e ) , one o b t a i n s f o r the molar e n t r o p y of butane the v a l u e 3 l 0 . q . J/mol K, t o be compared w i t h the e x p e r i m e n t a l v a l u e 3 1 0 . 2 J / mol Κ (17). I t f o l l o w s t h a t , i f i n a c h e m i c a l r e a c t i o n a mole­ c u l e i s o n l y p a r t l y m o d i f i e d , the p a r t of the m o l e c u l e which r e m a i n s unchanged c o n t r i b u t e s i n the same way to the t o t a l e n t r o p y of b o t h the r e a c t a n t s and of the p r o d u c t s . As a consequence, the e n t r o p y change accom­ p a n y i n g a g i v e n r e a c t i o n i s s i m p l y the d i f f e r e n c e be­ tween the c o n t r i b u t i o n t o the t o t a l e n t r o p y o f those groups which are m o d i f i e d i n the r e a c t i o n . C a l c u l a t i o n of Α 3 , The s i t u a t i o n i s p a r t i c u l a ­ r l y s i m p l e (Jj3) i n the case of the i n t e r m o l e c u l a r c h a i n p r o p a g a t i o n r e a c t i o n s , g e n e r a l l y r e p r e s e n t e d i n the f o l l o w i n g scheme: η

(6)

Taking S as the molar e n t r o p y of the R p a r t of the growing polymer c h a i n which remains unchanged a f t e r the r e a c t i o n , 3 as the molar e n t r o p y of the monomer i c u n i t formed i n the r e a c t i o n , and S ^ as the molar e n t r o p y of the r a d i c a l u n i t a t the end of the c h a i n , one o b t a i n s : R

r a u

S

R

+

Sum

+

s

S

r u "

=

V i "

%

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

2.

GUAiTA

Temperature Dependence of Cyclization Ratios

21

I n o t h e r words, a s f a r as t h e e n t r o p y change i s c o n ­ cerned, t h e p r o p a g a t i o n r e a c t i o n i s e q u i v a l e n t t o t h e i n s e r t i o n o f a monomer m o l e c u l e i n t h e i n n e r p a r t o f a growing c h a i n . I t i s p o s s i b l e t o go f u r t h e r c o n s i d e r i n g t h a t t h e e n t r o p y c o n t r i b u t i o n o f t h e l a t e r a l s u b s t i t u e n t s X and Y i n t h e monomer m o l e c u l e and i n t h e monomeric u n i t can be r e g a r d e d as t h e same, except f o r t h e e f f e c t s , which c a n however be a s s e s s e d , which depend upon t h e p o s s i b l e e x i s t e n c e o f c o n j u g a t i o n between t h e monomer double bond and one o f t h e s u b s t i t u e n t s , and t h e chan­ ges o c c u r r i n g i n t h e symmetry o f t h e m o l e c u l e s and i n the number o f p o s s i b l a f t e r the r e a c t i o n . Therefor that : Δ3

ρ

-

3(-CH -CC 2

+

- 3(CV(*

+

3

c Q n

.

+

(

?

)

R in σ ν

where 3(-0H9-C^) and S ( 0 Η ο = 0 < ) a r e t h e e n t r o p y c o n t r i ­ b u t i o n s o f t h e groups which a r e m o d i f i e d i n t h e r e a c ­ t i o n , Sconj i s the l o w e r i n g o f t h e monomer e n t r o p y due to c o n j u g a t i o n , σ i s t h e symmetry number o f t h e mono­ mer m o l e c u l e ( t h e symmetry number o f t h e monomeric u n i t formed i n r e a c t i o n ( 6 ) i s u s u a l l y 1 ) , * and ν i s the number o f o p t i c a l i s o m e r s formed i n the r e a c t i o n . Of c o u r s e , eq. (7) i s n o t l i m i t e d t o t h e i n t e r m o l e c u ­ l a r a d d i t i o n s t a k i n g p l a c e i n t h e f r e e r a d i c a l polyme­ r i z a t i o n o f u n c o n j u g a t e d d i e n e s , b u t s h o u l d be v a l i d f o r t h e c h a i n p r o p a g a t i o n talking p l a c e i n t h e f r e e r a ­ d i c a l p o l y m e r i z a t i o n o f any monomer. In Table I I I the experimental a c t i v a t i o n entropy of t h e c h a i n p r o p a g a t i o n i n the p o l y m e r i z a t i o n o f some t y p i c a l monomers i s compared w i t h t h e c a l c u l a t e d en­ t r o p y change accompanying the r e a c t i o n . C o n s i d e r i n g the l a r g e e x p e r i m e n t a l e r r o r s a f f e c t i n g t h e e v a l u a t i o n of t h e a b s o l u t e r a t e c o n s t a n t s ( f o r example, by t h e r o t a t i n g s e c t o r method, o r by n o n - s t a t i o n a r y k i n e t i c s ) the agreement i s q u i t e good, s u p p o r t i n g t h e assumed s i m i l a r i t y between t h e r e a c t i o n i n t h e g a s phase and i n s o l u t i o n , and showing t h a t t h e a c t i v a t i o n e n t r o p i e s s a t i s f a c t o r i l y compare w i t h t h e entropy changes r e s u l ­ t i n g from t h e complete r e a c t i o n .

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

22

POLYMERS

WITH

CHAIN-RING

STRUCTURES

Table I I I - Experimental a c t i v a t i o n entropy A s £ and c a l c u l a t e d e n t r o p y change A S f o r t h e c h a i n p r o p a g a t i o n i n t h e f r e e r a d i c a l po­ l y m e r i z a t i o n o f some monomers. p

-AS (J/raol K)

-AS* ( J / m o l K)

monomer

p

119.3 139.1 135.3 H3.7

styrene v i n y l acetate methyl a c r y l a t e methyl methacrylate

124.0 129.9 129.9 U1.3

T u r n i n g t o t h e comparison between t h e r a t e c o n s ­ t a n t s f o r the c h a i n p r o p a g a t i o n i n the f r e e r a d i c a l p o l y m e r i z a t i o n o f m e t h y l and b u t y l a e r y l a y e s , i t c a n be observed t h a t b o t h t h e s e r e a c t i o n s s h o u l d o c c u r w i t h the same e n t r o p y d e c r e a s e , because i d e n t i c a l dou­ b l e bonds a r e i n v o l v e d . From the e x p e r i m e n t a l d a t a by T v l e l v i l l e and B i c k e l ( ^ i ) and by Bengough and M e l v i l l e ( H ) r e l a t i v e to butyl acrylate, 4 p a i r s of a c t i v a t i o n energy and e n t r o p y can be c a l c u l a t e d , which a r e c o l l e ­ c t e d i n T a b l e IV. I t i s e v i d e n t t h a t the e x p e r i m e n t a l a c t i v a t i o n e n t r o p y which i s c l o s e s t t o t h e c a l c u l a t e d ASp f o r a l k y l a c r y l a t e s ( i . e . t h e A S v a l u e r e p o r t e d f o r methyl a c r y l a t e i n Table I I I ) i s J/mol Κ , whereas a l l the o t h e r a c t i v a t i o n e n t r o p i e s seem t o be too h i g h . The r a t e c o n s t a n t c a l c u l a t e d a t jO°C from p

T a b l e IV - E x p e r i m e n t a l a c t i v a t i o n energy and e n t r o p y and r a t e c o n s t a n t a t JO°C f o r t h e c h a i n p r o p a g a t i o n i n the f r e e r a d i c a l p o l y m e r i ­ z a t i o n of b u t y l a c r y l a t e .

Ref.

P (kJ/mol)

- AS* (J/mol K)

(li) (13) (15) (15)

23.07 9.63 23.07 9.60

H9.9 199.7 124.4 178.9

S

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

k

P

27 14

579 173

2.

GUAiTA

Temperature Dependence of Cyclization Ratios

23

t h i s v a l u e o f t h e a c t i v a t i o n e n t r o p y and the c o r r e s p o n d i n g v a l u e Ep = 2 3 . 0 7 kJ/mol i s kp = 5 7 9 , c l o s e t o the v a l u e kp = 5 Ç 0 c a l c u l a t e d a t 3 0 ° C from t h e d a t a o f Bagdasaryan (JU) r e l a t i v e t o m e t h y l a c r y l a t e : i n o t h e r words, i t seems n o t l i k e l y t h a t t h e c h a i n p r o p a g a t i o n s i n the p o l y m e r i z a t i o n o f m e t h y l and b u t y l a c r y i a t e s are s t r o n g l y d i f f e r e n t . C a l c u l a t i o n o f Δ 3 . The e v a l u a t i o n o f t h e en­ t r o p y change o c c u r r i n g i n t h e c y c l i z a t i o n r e a c t i o n s i s a l i t t l e more c o m p l i c a t e d t h a n t h e e v a l u a t i o n o f Δ3p, i n as much as i n t h e c y c l i z a t i o n r e a c t i o n s t h e product r a d i c a l i s d i f f e r e n ing c y c l i z a t i o n . η

I t seems r e a s o n a b l e t o assume even i n t h e p r e s e n t case t h a t t h e p a r t o f t h e growing c h a i n n o t d i r e c t l y i n v o l v e d i n t h e c y c l i z a t i o n r e a c t i o n does n o t c o n t r i ­ bute t o Δ 3 . T h e r e f o r e , c o n s i d e r i n g t h e f o l l o w i n g schemes: 0

'Ό

"Ό'

—

(Ρ·)

(Q ) #

where, a s u s u a l , Ti s t a n d s f o r t h e polymer c h a i n , one might e x p e c t t h a t t h e two c y c l i z a t i o n r e a c t i o n s a r e endowed w i t h t h e same e n t r o p y d e c r e a s e . As a c o n s e ­ quence: Δ3

=

3^

—

3^

c Q* Ρ· The d i f f e r e n c e between t h e molar e n t r o p i e s o f 3· and Ρ · r a d i c a l s h a s been r e l a t e d (Jj5) t o t h e d i f f e r e n c e between t h e molar e n t r o p i e s o f QH and PH m o l e c u l e s , which a r e o b t a i n e d from Q» and Ρ· r a d i c a l s by s a t u r a ­ t i n g t h e l o n e e l e c t r o n w i t h a Η atom. The f o l l o w i n g r e l a t i o n has been s u g g e s t e d ( 1 6 ) :

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS

24

AS

=

S™

-

S_

u

+

WITH

R In °*

W

CHAIN-RING

STRUCTURES

(8)

°*

where O Q . , σ ρ , σ and σ ρ ^ a r e the symmetry num­ b e r s of the s p e c i e s i n d i c a t e d . "Eq. ( 8 ) has been u s e d t o e v a l u a t e t h e e n t r o p y changes o c c u r r i n g i n t h e c y c l i z a t i o n r e a c t i o n s ( c a r ­ r i e d out i n t h e i d e a l gas s t a t e ) r e p r e s e n t e d i n F i g u ­ r e 1 . The most e v i d e n t S a t u r e o f t h e v a l u e s of t h e en­ tropy decreases c a l c u l a t e d f o r the c y c l i z a t i o n r e a c ­ t i o n s i s t h a t they a r e d e c i d e d l y lower than the e n t r o ­ py d e c r e a s e s c a l c u l a t e d a c c o r d i n g t o eq. ( 7 ) , a s s o c i a ­ t e d w i t h t h e i n t e r m o l e c u l a r a d d i t i o n s r e p r e s e n t e d as w e l l i n Figure 1. the c y c l i z a t i o n r e a c t i o n s a r e i n c o m p e t i t i o n w i t h t h e i n t e r m o l e c u l a r a d d i t i o n s , they a r e s t r o n g l y f a v o u r e d as f a r as t h e entropy changes a r e i n v o l v e d . As a c o n ­ sequence, when t h e r i n g s t r u c t u r e which c a n be formed i s n o t endowed w i t h h i g h t e n s i o n s on t h e v a l e n c e bonds and a n g l e s ( i . e . when t h e r i n g s t r u c t u r e h a s n o t a s t r o n g l y h i g h e r energy than the open s t r u c t u r e formed i n the i n t e r m o l e c u l a r a d d i t i o n ) , the c y c l i z a t i o n r e a c ­ t i o n i s f a s t e r . T h i s i s c e r t a i n l y n o t t h e case i n t h e p o l y m e r i z a t i o n o f b u t a d i e n e , where the f o r m a t i o n of the 3-niembered r i n g s would i n v o l v e a v e r y s m a l l e n t r o ­ py d e c r e a s e , b u t i s t o t a l l y s u p p r e s s e d by t h e h i g h en e r g y o f t h e s t r a i n e d v a l e n c e a n g l e s : as i t i s w e l l known, t h e c h a i n p r o p a g a t i o n r e a c t i o n s i n t h e polyme­ r i z a t i o n o f b u t a d i e n e e x c l u s i v e l y occur by i n t e r m o l e ­ cular additions. #

0

Η

On t h e c o n t r a r y , when 5- and 6-membered r i n g s c a n be formed, i . e . r i n g s p r a c t i c a l l y f r e e o f t e n s i o n s , the d e c r e a s e o f entropy o c c u r r i n g i n t h e c y c l i z a t i o n i s s t i l l s t r o n g l y lower than t h a t o c c u r r i n g i n t h e i n ­ t e r m o l e c u l a r a d d i t i o n , and the c y c l i z a t i o n a r e f a v o u ­ r e d on t h i s a c c o u n t . Comparison between c a l c u l a t e d d i f f e r e n c e s and e x p e r i m e n t a l d i f f e r e n c e s ASn - ASjf.

ΔS

0

-

ASp

The f i n a l p o i n t t o be d i s c u s s e d i s the p o s s i b i l i t y o f t r a n s f e r r i n g the above c o n c l u s i o n t o a c t u a l c y c l o p o l y ­ m e r i z a t i o n p r o c e s s e s , t h a t i s t o see i f , as i t has been a l r e a d y v e r i f i e d f o r the i n t e r m o l e c u l a r c h a i n p r o p a g a -

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

2.

Temperature Dependence of Cyclization Ratios

GUAITA

25

CYCLIZATION REACTIONS ( J / m o l Κ)

Λ

Δ.

—

23.7

32.0 -

Ο

41.9

74.9

81.9

INTERMOLECULAR PROPAGATION ( J / m o l K)

c=c

-C-Ç-

107.5

(n = 0)

124.1

(n jé 0)

γη

c=c

Figure 1.

Calculated entropy changes occurring in intramolecular cyclizations and intermolecular propagations.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

26

POLYMERS

WITH

CHAIN-RING

STRUCTURES

t i o n r e a c t i o n s , a c l o s e c o n n e c t i o n e x i s t s between t h e a c t i v a t i o n entropy and the e n t r o p y change o c c u r r i n g i n cyclization reactions. I t can be observed t h a t , as f a r as e n t r o p y d e c r e ­ ase of the c y c l i z a t i o n r e a c t i o n s i s concerned, i t sho­ u l d m a i n l y depend on t h e number o f bonds which change i n the r e a c t i o n t h e i r i n t e r n a l r o t a t i o n modes w i t h v i ­ b r a t i o n a l modes ( t h i s i s , o f c o u r s e , the r e a s o n why the a b s o l u t e v a l u e s o f A S i n F i g u r e 1 i n c r e a s e by i n c r e a s i n g the r i n g s i z e ) , whereas A S s h o u l d be s c a ­ r c e l y a f f e c t e d by t h e s u b s t i t u t i o n of one o r more o f the methylene groups between t h e carbon r a d i c a l and the double bond w i t mic groups, such a e q u i v a l e n t t o say t h a t t h e c o n t r i b u t i o n t o the e n t r o ­ py o f t h e i n t e r n a l r o t a t i o n around a g i v e n s i n g l e bond i s p r a c t i c a l l y t h e same i r r e s p e c t i v e of t h e h e i g h t of the p o t e n t i a l b a r r i e r s h i n d e r i n g r o t a t i o n . A c t u a l l y , f o r p o t e n t i a l b a r r i e r s f r o 4 t o 16 kJ/mol, t h a t i s from one t o the o t h e r o f the l i m i t s o f t h e h e i g h t s o f the p o t e n t i a l b a r r i e r s found f o r t h e r o t a ­ t i o n around t h e most common s i n g l e bonds o f o r g a n i c molecules, the entropy c o n t r i b u t i o n of the i n t e r n a l r o t a t i o n around a s i n g l e bond v a r i e s by 4 J/mol K, which means a change o f a few p e r c e n t i n t h e v a l u e o f C

C

A S . T h e r e f o r e , one c a n u s e t h e v a l u e s o f A S calcu­ l a t e d f o r c y c l i z a t i o n r e a c t i o n s i n v o l v i n g hydrocarbons such as those r e p r e s e n t e d i n F i g u r e 1, t o g e t h e r w i t h the v a l u e s o f ASp c a l c u l a t e d f o r t h e c o r r e s p o n d i n g i n t e r m o l e c u l a r a d d i t i o n s , t o evaluate the d i f f e r e n c e AS - ASp, and t o compare i t w i t h t h e e x p e r i m e n t a l d i f f e r e n c e between the a c t i v a t i o n e n t r o p i e s , as o b t a ­ i n e d from t h e temperature dependence o f t h e c y c l i z a ­ t i o n r a t i o s of r e a l cyclopolymerizations. I n T a b l e V a r e shown, f o r some monomers u n d e r g o ­ i n g c y c l o p o l y m e r i z a t i o n , t h e d i f f e r e n c e s AAS = A S ASp c a l c u l a t e d (8,9,J_6) a c c o r d i n g t o t h e p r o c e d u r e s p r e v i o u s l y d e s c r i b e d , and t h e e x p e r i m e n t a l d i f f e r e n ­ ces AAS* between the c o r r e s p o n d i n g a c t i v a t i o n e n t r o ­ p i e s . I n the case o f d i v i n y l e t h e r , a monomer which undergoes c y c l o p o l y m e r i z a t i o n y i e l d i n g 5- and 6-memb e r e d r i n g u n i t s (JJ3) i n a r a t i o i n c r e a s i n g w i t h i n ­ c r e a s i n g temperature ( 2 0 ) , t h e c a l c u l a t e d (2Λ) d i f f e C

C

C

C

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

2.

GUAITA

Temperature Dependence of Cyclization Ratios

27

T a b l e V - C a l c u l a t e d Δ AS and e x p e r i m e n t a l Δ A S * f o r the c h a i n p r o p a g a t i o n r e a c t i o n s i n the f r e e r a d i c a l c y c l o p o l y m e r i z a t i o n o f some monomers, ring size

monomer

diphenyihexadiene a c r y l i c anhydride m e t h a c r y l i c anhydride o-divinylbenzene d i v i n y l ether

A AS (J/mol K)

A AS* ( J / mol Κ )

5 6 6

88.8 49.2

86.0 46.2

60.6

7 5,6

53.5 30.2

66.5 46.6 31.0

+ + + + +

10.8 4.4 15.6

H.8 2.0

r e n c e Δ Δ 3 = Δ S - - A S 6 between the e n t r o p y changes o c c u r r i n g i n t h e 5- and 6-membered r i n g c l o s u r e i s compared w i t h t h e e x p e r i m e n t a l d i f f e r e n c e Δ Δ 3 = A S ^ Δ 3 6 between the a c t i v a t i o n e n t r o p i e s o f t h e s e two reactions. The agreement between c a l c u l a t e d and e x p e r i m e n t a l d i f f e r e n c e s i s e v i d e n t l y v e r y good. T h i s means t h a t i t i s c o r r e c t t o assume t h a t t h e e n t r o p y d e c r e a s e s o c c u r ­ r i n g i n b o t h c y c l i z a t i o n s and i n t e r m o l e c u l a r a d d i t i o n s are c l o s e t o the corresponding a c t i v a t i o n e n t r o p i e s . But i t means a l s o t h a t t h e c y c l i z a t i o n r e a c t i o n s t a k ­ i n g p l a c e i n the u s u a l c y c l o p o l y m e r i z a t i o n p r o c e s s e s a r e e f f e c t i v e l y f a v o u r e d by a s m a l l e r a c t i v a t i o n e n ­ tropy. c

C

0

Literature

cited

1. 2.

B u t l e r , G.B. J . Polymer S c i . 1 9 6 0 , 4 8 , 2 7 9 . B u t l e r , G.B.; Brooks, T.W. J . 0rg. Chem. 1 9 6 3 , 2 8 , 2699. 3 . Butler, G.B.; Raymond, M.A. J . Org. Chem. 1965, 3 0 , 2410. 4 · Mercier, J ; Smets, G. J . Polymer S c i . 1 9 6 2 , 57, 7 6 3 . 5. Gribbs, W.E. J . Polymer S c i . 1964, A 2 , 4815. 6 . Minoura, Y; Mitoh, M. J . Polymer S c i . 1965, A 3 , 2 1 4 9 . 7 . Chiantore, O; Camino, G.;Chiorino, A ; G u a i t a , M. Makromol. Chem. 1977, 178, 119. 8 . Chiantore, 0 ; Camino, G; Chiorino, Α . ; G u a i t a , M. Makromol. Chem. 1977, 178, 1 2 5 .

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS

28

WITH

CHAIN-RING

STRUCTURES

9. Costa, L.; Guaita, Μ. "Cyclopolymerization and Po­ lymers with Chain-Ring Structures"; American Chemi­ c a l Society: Washington, DC, 1982. 10. Butler, G.B.; Raymond, M.A. J . Polymer S c i . 1965, A3, 3 4 1 3 . 1 1 . Gibbs, W.E.; Barton, J.M. "The Mechanism of Cyclo­ polymerization of Unconjugated D i o l e f i n s " , i n " K i ­ n e t i c s and Mechanisms of Polymerizations", edited by Ham, G.E.; Edward Arnold (Publisher) Ltd, London, 1967; v o l . I; p. 1 3 3 . 12. Matheson, M.; Auer, E.; Bevilacqua, E.; Hart, E. J . Am. Chem. Soc. 1951, 73, 5 3 9 5 . 1 3 . M e l v i l l e , H.W.; 1949, 4 5 , 1049 14. Sinitsyna, Z.A.; Bagdasaryan, Kh.S. Zh. F. Ch. 1958, 32, 1319. 15. Bengough, W.J.; M e l v i l l e , H.W. Proc. Roy. Soc. (London) 1954, 2 2 5 , 3 3 0 . 16. Guaita, M. Makromol. Chem. 1972, 157, 111. 17. S t u l l , D.R.; Westrum, E.F.; Sinke, G.C. "The Che­ mical Thermodynamics of Organic Compounds"; John Wiley & Sons, London, 1969; p.245. 18. Guaita, M. Makromol. Chem. 1972, 154, 191 . 19. Aso, C.; Ushio, S.; Sogabe, M. Makromol. Chem. 1967, 100, 1 0 0 . 2 0 . Guaita, M.; Camino, G.; T r o s s a r e l l i , L. Makromol. Chem. 1971, 149, 7 5 . 2 1 . Costa, L.; Chiantore, O.; Guaita, M. Polymer 1978, 19, 2 0 2 . RECEIVED March 8,

1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

3 Intramolecular Addition Modes in Radical Cyclopolymerization of Some Unconjugated Dienes AKIRA MATSUMOTO, KUNIO IWANAMI, TAKAO KITAMURA, and MASAYOSHI OIWA Kansai University, Department of Applied Chemistry, Faculty of Engineering, Suita, Osaka 564, Japan GEORGE B. BUTLER University of Florida, Center for Macromolecular Science, Gainesville, FL 32611 The f a c t o r s modes were i n v e s t i g a t e d i n d e t a i l i n the r a d i c a l c y c l o p o l y m e r i z a t i o n of some unconjugated d i e n e s . Thus, i n diallyl p h t h a l a t e , only the cyclic polymer of an 11-membered r i n g was o b t a i n e d , whereas 10membered r i n g formation was observed i n diallyl ali­ phatic dicarboxylates. In d i m e t h a l l y l d i c a r b o x y l a t e s the i n t r a m o l e c u l a r head-to-head(hh) a d d i t i o n was h i g h l y enhanced compared with corresponding diallyl dicarboxylates. In a c r y l i c anhydride, the 5-membered r i n g formation was favored w i t h the i n c r e a s e of the p o l a r i t y of s o l v e n t , the e l e v a t i o n of temperature, and the decrease of monomer c o n c e n t r a t i o n ; thus, the r i n g s i z e of c y c l i c s t r u c t u r e could be f r e e l y c o n t ­ rolled. In m e t h a c r y l i c anhydride, the analogous r e s u l t s were obtained at elevated temperatures. In allyl methacrylate and allyl a t r o p a t e , the enhanced tendency to c y c l i z e and the h i g h l y o c c u r r i n g intra­ molecular hh a d d i t i o n were observed above the c e i ­ ling temperatures of the corresponding a l k y l αsubstituted acrylates. These r e s u l t s are discussed from the thermo­ dynamical standpoint. It i s w e l l known that h e a d - t o - t a i l ( h t ) a d d i t i o n f o r the attack of a growing chain r a d i c a l on a monomer i s predominant compared with other types of a d d i t i o n modes such as head-to-head(hh), t a i l to-head, and t a i l - t o - t a i l i n the r a d i c a l p o l y m e r i z a t i o n of v i n y l monomers, thus forming the polymer e x c l u s i v e l y of ht s t r u c t u r e . This f a c t has been explained by some q u a l i t a t i v e c o n s i d e r a t i o n s of resonance s t a b i l i t y and s t e r i c f a c t o r s leading to the intermediate formation of the more s t a b l e free r a d i c a l and, furthermore, by t h e o r e t i c a l treatment based on molecular o r b i t a l t h e o r y ( l ) . In t h i s connection, most of the e a r l y l i t e r a t u r e on the s t r u c t u r e of

0097-6156/82/0195-0029$06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

30

POLYMERS

WITH

CHAIN—RING

STRUCTURES

c y c l i c polymers obtained i n the c y c l o p o l y m e r i z a t i o n of 1,6-dienes have assumed that a six-membered r i n g i s formed i n conformity w i t h expected thermodynamic s t a b i l i t y of the secondary or t e r t i a r y r a d i c a l formed v i a i n t r a m o l e c u l a r ht a d d i t i o n compared with the r e q u i r e d primary r a d i c a l f o r hh a d d i t i o n . However, numerous r e p o r t s of predominant five-membered r i n g formation v i a i n t r a m o l e c u l a r hh a d d i t i o n of the u n c y c l i z e d r a d i c a l to the i n t e r n a l double bond have been r e c e n t l y published; i n p a r t i c u l a r , the c y c l o p o l y m e r i z a t i o n s of N - s u b s t i t u t e d d i m e t h a c r y l amides(2-5), d i a l l y l amines and t h e i r s a l t s ( 6 - 1 1 ) , d i v i n y l a c e t a l s (12), and d i v i n y l phosphonates(13) could be presented as t y p i c a l examples. These f i n d i n g s are c l o s e l y r e l e v a n t to the recent development of a n a l y t i c a l procedures e s p e c i a l l y i n c l u d i n g 13C-NMR spectroscopy although chemical analyses and IR spectroscopy were employed e a r l i e r f o r th i t should be noted tha the c y c l o p o l y m e r i z a t i o n of d i v i n y l formal and d i a l l y l ammonium s a l t s : Thus, Tsukino and Kunitake(12) have reported r e c e n t l y the e x c l u s i v e five-membered r i n g formation from a d e t a i l e d i n v e s t i g a t i o n of t h e C - N M R spectrum of c y c l i c p o l y ( d i v i n y l formal) as opposed to the e a r l i e r r e s u l t s of Matsoyan(14) who had determined by chemical means that the c y c l i c s t r u c t u r e was a six-membered r i n g , although Minoura and Mitoh(15) have claimed some f i v e membered r i n g formation from a higher content of 1,2-glycol s t r u c ture i n p o l y ( v i n y l a l c o h o l ) obtained by h y d r o l y s i s of p o l y ( v i n y l formal) than that i n commercial p o l y ( v i n y l a l c o h o l ) . Chemical evidence has been a l s o presented to support the c y c l o p o l y m e r i z a t i o n hypothesis of d i a l l y l ammonium s a l t s by B u t l e r , Crawshaw, and M i l l e r ( 1 6 ) c o n t r a r y to recent s p e c t r o s c o p i c evidences(6-11). Another approach to the study of the c y c l i c u n i t s formed i n these c y c l o p o l y m e r i z a t i o n s i s through the study of the r a d i c a l c y c l i z a t i o n r e a c t i o n of s e l e c t e d model compounds. Thus, extensive s t u d i e s have shown that the five-membered r i n g i s predominant, while new evidence i n d i c a t e s that r a d i c a l s t a b i l i t y exerts a marked i n f l u e n c e on the r i n g s i z e . These c o n f l i c t i n g aspects of c y c l o p o l y m e r i z a t i o n have been discussed i n d e t a i l by B u t l e r ( 1 7 ) ; he has pointed out that c o n s i d e r a b l y more i n v e s t i g a t i o n s w i l l be necessary before d e f i n i t e conclusions can be drawn with respect to the r a t i o of f i v e - to six-membered r i n g s i n the many cyclopolymers already s y n t h e s i z e d , and a s a t i s f a c t o r y e x p l a n a t i o n f o r these extensive v a r i a t i o n s from one system to another i s a v a i l a b l e . Thus, we i n v e s t i g a t e d i n d e t a i l the f a c t o r s i n f l u e n c i n g i n t r a molecular a d d i t i o n modes i n the r a d i c a l c y c l o p o l y m e r i z a t i o n of some unconjugated dienes, i n c l u d i n g d i a l l y l and d i m e t h a l l y l dicarboxyl a t e s , a c r y l i c and m e t h a c r y l i c anhydrides, and a l l y l ^ - s u b s t i t u t e d a c r y l a t e s and d i s c u s s e d the s e l e c t i v i t y of r e a c t i o n mode of i n t r a molecular hh or ht a d d i t i o n i n terms of the thermodynamical standp o i n t . The present a r t i c l e gives a summary of our recent work i n c l u d i n g published papers(18-23).

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

3.

MATSUMOTO

ET

AL.

Intramolecular Addition Modes

31

C y c l o p o l y m e r i z a t i o n of D i a l l y l and D i m e t h a l l y l Dicarboxylates In our c o n t i n u i n g studies of the c y c l o p o l y m e r i z a t i o n of d i a l l y l d i c a r b o x y l a t e s ( 2 4 ) , we attempted to determine the r i n g s i z e of the c y c l i c u n i t of the r e s u l t i n g polymer. During the course of t h i s i n v e s t i g a t i o n , i t has been c l e a r l y demonstrated that an anomalous hh a d d i t i o n occurs remarkably i n the r a d i c a l p o l y m e r i z a t i o n of monoallyl and monomethallyl carboxylates(18,21): Figure 1 shows a t y p i c a l example of the h i g h l y o c c u r r i n g hh a d d i t i o n i n the r a d i c a l p o l y m e r i z a t i o n of a l l y l acetate(AAc) and m e t h a l l y l acetate. This has been i n t e r p r e t e d from the f o l l o w i n g standpoints(21): In the r a d i c a l p o l y m e r i z a t i o n of a l l y l i c compounds, which are t y p i c a l unconjugated monomers, the resonance s t a b i l i z a t i o n of the growing secondary or t e r t i a r y r a d i c a l by the s u b s t i t u e n t i s not so s i g n i f i cant. In other words, th between two types of intermediat t i a r y head and primary t a i l r a d i c a l s , i s s m a l l , implying the reduced r e a c t i o n s e l e c t i v i t y governed by the thermodynamic s t a b i l i ty of the r e s u l t i n g r a d i c a l s i n comparison with the cases of common v i n y l monomers. This d i s c u s s i o n suggests the s i g n i f i c a n c e of the s t e r i c f a c t o r f o r the s e l e c t i v i t y of a d d i t i o n modes i n the r a d i c a l p o l y m e r i z a t i o n of a l l y l i c compounds because s t e r i c e f f e c t tends to favor the hh or t t s t r u c t u r e , that i s , the a l t e r n a t e hh or t t p o l y mer should be comparatively f r e e from s t e r i c r e p u l s i o n between s u b s t i t u e n t s made evident i n the i n s p e c t i o n of the molecular model (25,26). Thus, the e f f e c t of the s i d e group s t e r i c hindrance a r i s i n g from the a c i d moiety of monoallyl carboxylates, i n c l u d i n g AAc(18), a l l y l benzoate(21), a l l y l propyl succinate(APSu)(20), a l l y l propyl phthalate(APP)(20), and a l l y l propyl c i s - l , 2 - c y c l o hexanedicarboxylate(APCH)(20T~was examined and the contents of hh linkage of the polymers obtained i n bulk at 80°C were estimated to be 8.5, 11, 14, 15, and 19%, r e s p e c t i v e l y . Consequently, the occurrence of hh a d d i t i o n was enhanced with an increase i n the b u l k i n e s s of the a c i d moiety of monoallyl carboxylates as the s i d e group of the r e s u l t i n g polymers i n conformity with our expectation. Such a s t r i k i n g f e a t u r e of a l l y l i c compounds that the s e l e c t i v i t y of a d d i t i o n modes i s governed s i g n i f i c a n t l y by any other f a c t o r s than the thermodynamic s t a b i l i t y of the r e s u l t i n g r a d i c a l s has been q u i t e r e f l e c t e d i n the i n t r a m o l e c u l a r a d d i t i o n modes i n the c y c l o p o l y m e r i z a t i o n of d i a l l y l and d i m e t h a l l y l d i c a r b o x y l a t e s as f o l l o w s : The polymerizations of three kinds of d i a l l y l d i c a r b o x y l a t e s , i n c l u d i n g d i a l l y l phthalate(DAP)(19), d i a l l y l s u c c i n a t e ( DASu)(20), and d i a l l y l cis-l,2-cyclohexanedicarboxylate(DACH)(20), a l l of which can form the same r i n g s i z e , were c a r r i e d out i n bulk or i n benzene s o l u t i o n s at 80°C, using benzoyl peroxide as the initiator. F i g u r e 2 shows the r e l a t i o n s h i p s between the percentage of hh linkage and the content of u n c y c l i z e d u n i t , i . e . , 100 - f ; the r e s u l t s have been discussed from the f o l l o w i n g three p o i n t s : F i r s t , the contents of hh linkage were q u i t e high f o r a l l uncycl i z e d p o l y m e r s ( f = 0) which were prepared from the model polymeric

c

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS

32

WITH

CHAIN-RING

STRUCTURES

Figure 1. Dependence of the percentage of hh linkage on polymerization tempera­ ture in bulk polymerizations. Key: O, allyl acetate; and · , methallyl acetate. (Reproduced, with permission, from Ref. 21. Copyright 1981, J. Polym. Sci. Polym. Lett. Ed.)

ο L_

,

ι

0

.

50 100

- f

I 100

c

(#)

Figure 2. Relationship between the percentage of hh linkage and the content of uncyclized unit, 100 — f , obtained for cyclopolymerizations in benzene solutions at 80°C. Key: O, diallyl phthalate; Q, diallyl succinate; and · , diallyl cis-i2-cyclohexanedicarboxy late. (Reproduced, with permission, from Ref. 21. Copyright 1981, J. Polym. Sci. Polym. Lett. Ed.) c

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

3.

MATSUMOTO

ET

AL.

Intramolecular Addition Modes

33

zations of APP, APSu, and APCH corresponding to monoallyl counterparts of DAP, DASu, and DACH, r e s p e c t i v e l y , as discussed above i n detail. Second, the contents of hh linkage tended to decrease w i t h an increase i n the c y c l i z e d u n i t ; t h i s i s a s c r i b e d to the reduced s t e r i c crowding by the i n c o r p o r a t i o n of c y c l i z e d s t r u c t u r e i n t o the r e s u l t i n g polymer because the carbon numbers of backbone polymer chain i n c r e a s e by four with the formation of c y c l i z e d u n i t . T h i r d , the minimum hh linkage was observed i n the c y c l o p o l y m e r i z a t i o n of DASu and DACH, whereas i n the c y c l o p o l y m e r i z a t i o n of DAP the content of hh linkage decreased only l i n e a r l y with increased c y c l i z a t i o n . That i s , the c y c l i z e d DASu and DACH polymers contained high hh l i n k a g e s , whereas on the c o n t r a r y , c y c l i c poly-DAP had no hh l i n k a g e . Here i t should be remembered that the content of hh l i n kage of the c y c l i z e d polymer was determined from the ^C-NMR spectrum of poly-AAc derived b c a t i o n of the c y c l i z e d d i a l l y Consequently, two p o s s i b l e r e a c t i o n paths, i . e . , an i n t r a m o l e c u l a r hh a d d i t i o n of u n c y c l i z e d head r a d i c a l and an i n t e r m o l e c u l a r hh a d d i t i o n of c y c l i z e d head r a d i c a l should be considered f o r the i n c o r p o r a t i n g process of hh linkage i n t o the d e r i v e d poly-AAc chain. The d i s c r i m i n a t i o n of these two r e a c t i o n s i s not easy, but the p o s s i b i l i t y of the occurrence of an i n t e r m o l e c u l a r hh a d d i t i o n of c y c l i z e d head r a d i c a l may be omitted by c o n s i d e r i n g the s t e r i c crowding i n the r e s u l t i n g c y c l i z e d polymer. Thus, the f o l l o w i n g three types of t y p i c a l cyclopolymers w i l l be given s c h e m a t i c a l l y : R

R

R

R

where R i s H f o r d i a l l y l d i c a r b o x y l a t e s and CH3 f o r d i m e t h a l l y l d i c a r b o x y l a t e s . The polymers of A, B, and C types are obtainable v i a intramolecular hh and i n t e r m o l e c u l a r t t a d d i t i o n s , intramolec u l a r ht and i n t e r m o l e c u l a r ht a d d i t i o n s , and i n t r a m o l e c u l a r t t and i n t e r m o l e c u l a r hh a d d i t i o n s , r e s p e c t i v e l y . E v i d e n t l y , the A-type polymer i s most favorable i n terms of s t e r i c r e p u l s i o n between large c y c l i c u n i t s . On the other hand, no hh linkage of the c y c l i c poly-DAP means that the i n t r a m o l e c u l a r c y c l i z a t i o n of u n c y c l i z e d r a d i c a l and the

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

34

POLYMERS

WITH

CHAIN-RING

STRUCTURES

i n t e r m o l e c u l a r propagation of c y c l i z e d r a d i c a l proceed only v i a ht a d d i t i o n as completely opposed to our expectation. The nonoccur­ rence o f i n t r a m o l e c u l a r hh a d d i t i o n i s a t t r i b u t e d to the f a c t that the occurrence of hh a d d i t i o n , i . e . , the formation of ten-membered r i n g , r e q u i r e s the s a c r i f i c e of resonance s t a b i l i z a t i o n between carbonyl double bond and aromatic benzene r i n g because of the l o s s of c o p l a n a r i t y as i s expected from the molecular model(19,20). Moreover, the s e l e c t i v e i n t e r m o l e c u l a r ht a d d i t i o n of c y c l i z e d head r a d i c a l i n the c y c l o p o l y m e r i z a t i o n of DAP would be as a r e s u l t of nonoccurrence o f s t e r i c a l l y l e s s f a v o r a b l e i n t e r m o l e c u l a r hh a d d i t i o n l e a d i n g to the C-type polymer. For the c y c l o p o l y m e r i z a t i o n of d i m e t h a l l y l d i c a r b o x y l a t e s the formation of the B-type polymer should be c o n s i d e r a b l y s t e r i c a l l y hindered compared with d i a l l y l d i c a r b o x y l a t e s from the s i m i l a r standpoints f o r the monomethally minant occurrence o f and discussed i n d e t a i l from a thermodynamical standpoint(21); thus, the i n c r e a s e i n the occurrence of i n t r a m o l e c u l a r hh a d d i t i o n was expected. The polymerizations o f d i m e t h a l l y l phthalate(DMAP) and d i m e t h a l l y l cis-l,2-cyclohexanedicarboxylate(DMACH) were conducted i n bulk a t 80°C, using benzoyl peroxide as the i n i t i a t o r . The contents of hh linkage o f the r e s u l t i n g polymers were estimated to be 19% f o r DMAP and 23% f o r DMACH i n a markedly h i g h percentage compared with 6.5% f o r both DAP and DACH of the corresponding d i a l l y l d i c a r b o x y l a t e s . From these r e s u l t s , i t has been suggested that an i n t r a m o l e c u l a r hh a d d i t i o n i n the c y c l o p o l y m e r i z a t i o n of unconjugated dienes be promoted above the c e i l i n g temperature f o r ht a d d i t i o n i n the p o l y m e r i z a t i o n of monoene counterparts; t h i s was developed f o r the c y c l o p o l y m e r i z a t i o n of a l l y l 0(-substituted a c r y l a t e s and m e t h a c r y l i c anhydride as w i l l be discussed l a t e r . C y c l o p o l y m e r i z a t i o n of A l l y l PC-Substituted

Acrylates

In connection with the preceding d i s c u s s i o n , i t should be r e c a l l e d that the c e i l i n g temperatures i n the p o l y m e r i z a t i o n of methacrylates as t y p i c a l 0(,0 = k /k c c AS

A O

A A

-==V

k

ΟΛ,Α·

BS. r

^B-

Β·

— Ο Λ , Α ·

k —

OA,A*

t

ss

k . WS-

i

+ Anh — ^

3

=k

B A

/k BS

'λΛ,Α·

The c o p o l y m e r i z a t i o n process can thus be considered t o be a M a r k o f f i a n process i n v o l v i n g three s t a t e s , i n which the f o l l o w i n g transition probabilities prevail.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

4.

N E U M A N N A N D HARWOOD

Ρ (A/A)

Styrene-Methyl Methacrylate Copolymers

= (Anh)/((Anh)+r

P(B/A) = r 7 ( ( A n h + r c

P(S/A) - 1 - Ρ (A/A)

c

51

+ (S)/n)

c

+ (S)/n)

- P(B/A)

P(S/B) = ( S ) / ( ( S ) + r ( A n h ) ) 3

P(B/B =

Ο

P(A/B) = 1 - P(S7B) P(A/S) = (Anh)/((Anh) + r ( S ) ) 3

P(B/S) = Ο P(S/S) = 1 - P(A/S) Following methods reviewed p r e v i o u s l y (16), these t r a n s i t i o n p r o b a b i l i t i e s can be used to c a l c u l a t e the compositions of styrenem e t h a c r y l i c anhydride copolymers. Thus, the method of P r i c e (17) y i e l d s the f o l l o w i n g r e s u l t s , where P ( S ) , P(A) and P(B) represent the r e l a t i v e concentrations o f the f o l l o w i n g groups.

CH 'VXSHz-CH

3

CH -C-^A,-CH -C H" or I · 2

2

0=(

r « o=c I CH -C II CH

x

w

ρ(A) F

W

c

c

o^ -4 / ^o : ; n

!

3

p r q

xr^

I

1

2

ι

Β

_ (P(B/A)P(S/B) + P(S/A)) 1 + P(A/B) (A/B) + P(S/A) - Ρ P(S/S) - P(S/S)P(B/A) + P(B/A)P(S/B) =

1

P

S

* < > 1 + P(B/ (B/A)

P(B) = P(A)P(B/A) Knowing these r e l a t i v e c o n c e n t r a t i o n s and t r a n s i t i o n p r o b a b i l i t i e s , p r o b a b i l i t i e s f o r v a r i o u s sequences of S, A and Β e n t i t i e s present i n styrene-methacrylic anhydride copolymers can be c a l c u l a t e d i n the usual way, v i z . ,

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

52

POLYMERS

P(SAB) =

WITH CHAIN-RING STRUCTURES

P(S)P(A/S)P(B/A)

P(AABS) =

P(A)P(A/A)P(B/A)P(S/B)

etc. 11

The r e s u l t s of such c a l c u l a t i o n s need to be " t r a n s l a t e d to o b t a i n the r e l a t i v e c o n c e n t r a t i o n s of styrene u n i t s , F , c y c l i z e d metha­ c r y l i c anhydride u n i t s , F , and u n c y c l i z e d m e t h a c r y l i c anhydride u n i t s , F , present i n s t y r e n e - m e t h a c r y l i c anhydride copolymers. To do t h i s , i t must be r e a l i z e d that each Α-entity corresponds t o a m e t h a c r y l i c anhydride u n i t and that each Α-entity which i s f o l ­ lowed by a B - e n t i t y i s c y c l i z e d . Such c o n s i d e r a t i o n s l e a d to the following results. s

c

u

F

s

=

F

c

= P(A)-P(B/A)/CP(S)

+ P(S))

Fu = 1 - F s - Fc Sequence p r o b a b i l i t i e s may a l s o be c a l c u l a t e d , v i z . , r

r

ρ/ χ PCSUC)

P(S)-P(A/S)-P(A/A)-P(B/A)

ςττΓ

ρ,

F^bUU; ς

ι

π

η

p

(

s

)

+

p

(

A

)

_ P ( S ) - P ( A / S ) P ( A / A ) ( 1 - P(B/A))

-

p

(

s

)

+

p

(

A

)

Of s p e c i a l i n t e r e s t to the present study i s the c a l c u l a t i o n of the compositions and sequence d i s t r i b u t i o n s of styrene-MMA copolymers derived from s t y r e n e - m e t h a c r y l i c anhydride copolymers. A " t r a n s l a t i o n " technique based on the f a c t that A- and B- e n t i ­ t i e s both l e a d to MMA u n i t s , l e a d s to the f o l l o w i n g r e s u l t s : F

S

= P(S)/(P(A) + P(B) + P(S))= P(S)

F

M

= 1 - F

S

= P(A) + P(B)

Since A- and B- e n t i t i e s can both become MMA-units i n the d e r i v e d copolymers, the c a l c u l a t i o n of sequence p r o b a b i l i t i e s i s more d i f ­ f i c u l t than f o r the case of s t y r e n e - m e t h a c r y l i c anhydride copoly­ mers; there are o f t e n many combinations of Α-, B- and S- e n t i t i e s that can y i e l d a g i v e n sequence of styrene and MMA u n i t s . For example, an MMM t r i a d can r e s u l t from the f o l l o w i n g sequences: AAA, (A)BAA, (A)BAB, ABA and AAB. Thus, Ρ (MMM)

= Ρ(Α)·Ρ(Α/Α)

2

+ P(B)P(A/A)

2

+ P(B)P(A/B)P(B/A)

P(A)P(B/A)P(A/B)

+

+

P(A)P(A/A)P(B/A)

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

4.

NEUMANN

A N D HARWOOD

Styrene-Methyl Methacrylate Copolymers

53

Similarly, P(MMS) = P(B)P(A/B)P(S/B) + P(A)P(A7A)P(S7A) + P(A)P(B7A)P(S/B) P(SMM) = P(S)P(A/S)P(A/A) + P(S)P(A7S)P(B/A) P(SMS) = P(S)P(A/S)P(S/A) In a s i m i l a r manner, p r o b a b i l i t i e s o f other sequences can a l s o be c a l c u l a t e d . For analyses of the methoxy proton resonance p a t t e r n s of the derived S/MMA copolymers, M-centered t r i a d f r a c t i o n s are needed. These can be c a l c u l a t e d i n the usual way, v i z . ,

MMM

Ρ (MMM) P(M)

f 5

=

(MMS+SMM

On the b a s i s of the above c o n s i d e r a t i o n s , two computer pro­ grams have been w r i t t e n to c a l c u l a t e MMA-centered t r i a d and pentad d i s t r i b u t i o n s f o r S/MMA copolymers d e r i v e d from styrene-methacrylic anhydride copolymers. One program, w r i t t e n s p e c i f i c a l l y f o r t h i s a p p l i c a t i o n , i s programmed with the r e s u l t s of the t r a n s l a t i o n s d e s c r i b e d above. The second program i s a combination o f one of our programs f o r c a l c u l a t i n g s t r u c t u r a l f e a t u r e s of terpolymers (18), and a subroutine to perform the necessary t r a n s l a t i o n s . Both pro­ grams y i e l d the same r e s u l t s , but the second one enables c a l c u ­ l a t i o n s to be performed f o r polymers prepared i n high conversions. R e s u l t s and D i s c u s s i o n The copolymerization of m e t h a c r y l i c anhydride with styrene has been i n v e s t i g a t e d by s e v e r a l groups. With the exception of Smets, e t a l . (12) i t has been reported that the m e t h a c r y l i c an­ hydride u n i t s i n the polymers are almost completely c y c l i z e d . This i s a l s o i n accord w i t h our experience. I t proved d i f f i c u l t to separate unpolymerized m e t h a c r y l i c anhydride from the copolymers, and considerable e f f o r t was made to remove unreacted monomer from the polymers. H-NMR spectroscopy proved to be an e f f e c t i v e me­ thod f o r d i s t i n g u i s h i n g u n c y c l i z e d m e t h a c r y l i c anhydride u n i t s present on the polymers from adsorbed monomer (see Experimental). In many samples, no resonances due to u n c y c l i z e d anhydride u n i t s were detected. T h i s was p a r t i c u l a r l y t r u e of copolymers with high styrene contents. Table I l i s t s the compositions determined f o r styrene-methacrylic anhydride copolymers prepared a t 40°. The styrene contents of the copolymers a r e i n good agreement w i t h those reported by Smets, et a l . , f o r copolymers prepared from comparable monomer r a t i o s , but where the anhydride c o n c e n t r a t i o n was ^2M. However, Smets, e t a l . r e p o r t that 30-50 percent o f the anhydride u n i t s were u n c y c l i z e d i n t h e i r copolymers and i t appears that the extent of c y c l i z a t i o n i s b e t t e r than 90 percent, g e n e r a l l y about X

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

54

POLYMERS

WITH

CHAIN-RING

STRUCTURES

95 percent, i n our samples. I t i s d o u b t f u l that the use of a lower anhydride c o n c e n t r a t i o n (^1M) i n our p r e p a r a t i o n s i s r e s p o n s i b l e for this difference. Roovers and Smets have d e r i v e d the f o l l o w i n g equation, which r e l a t e s the f r a c t i o n of anhydride u n i t s c y c l i z e d ( f ) t o the c y c l i ­ z a t i o n constants r and and t o monomer c o n c e n t r a t i o n s . Since c

c

f

r C

r

c

c?

[M] was 0.936M i n our work, a p l o t of γ— vs (S) should y i e l d a s t r a i g h t l i n e having l / r ^ as slope and 1 + 0.936/r as i n t e r ­ cept. C o n s t r u c t i o n o the s u r p r i s i n g r e s u l t bably i n c o n f l i c t with the k i n e t i c model (9) d e s c r i b e d e a r l i e r i n t h i s paper, s i n c e r ' = Γ ·Γχ and r i must c l e a r l y be l e s s than one. Perhaps a penultimate e f f e c t makes i t e a s i e r f o r an anhydride r a d i c a l to c y c l i z e i f i t i s attached to a styrene u n i t than i f i t i s attached to a c y c l i z e d anhydride u n i t . T h i s would cause the extent of c y c l i z a t i o n to be higher i n copolymers with high styrene contents than i n those with low styrene contents. T h i s p o i n t m e r i t s a d d i t i o n a l study. For the present, we w i l l u t i l i z e an r value of ^40M f o r c a l c u l a t i n g s t r u c t u r a l f e a t u r e s o f S/MMA copoly­ mers d e r i v e d from styrene-methacrylic anhydride copolymers. c

c

c

0

c

Smets, e t a l . (12) noted that the compositions of styrenem e t h a c r y l i c anhydride copolymers prepared from given styrenem e t h a c r y l i c anhydride mixtures were independent o f the amount of solvent present i n the system and concluded that r i and r i n the k i n e t i c scheme o u t l i n e d above must be equal. T h i s c o n c l u s i o n , which was a l s o accepted by Baines and Bevington (13), enabled r e ­ a c t i v i t y r a t i o s f o r t h i s copolymerization system to be c a l c u l a t e d by use of the standard copolymer equation. U n f o r t u n a t e l y , t h i s i s not a v a l i d c o n c l u s i o n ; the r e s u l t s i n Table I I show that f o r con­ d i t i o n s s i m i l a r to those employed i n the previous work, the styrene contents of the copolymers are imperceptibly a f f e c t e d by d i l u t i o n of the system, even when r i s f i v e times g r e a t e r or l e s s than r i . Due to the d i f f i c u l t y of working with styrene-methacrylic anhydride copolymers, we have e l e c t e d to determine r e a c t i v i t y r a t i o s and c y c l i z a t i o n constants from the compositions and s t r u c ­ t u r e s of styrene-MMA copolymers d e r i v e d from these copolymers. As i s discussed i n the experimental s e c t i o n i t i s p o s s i b l e to measure the styrene contents and the p r o p o r t i o n s of methoxy proton r e s o ­ nance o c c u r r i n g i n three d i f f e r e n t areas (designated A, Β and C) from the H-NMR s p e c t r a of S/MMA copolymers. The p r o p o r t i o n s of methoxy proton resonance observed i n the A ( F ^ ) , Β ( F B ) and C (Fc) areas obey the f o l l o w i n g r e l a t i o n s h i p s i n conventional styrene-MMA copolymers (6 ,_7). 3

3

X

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

4.

NEUMANN

A N D HARWOOD

Styrene-Methyl Methacrylate Copolymers

F

A

=

Ρ (MMM) + 0.5 P(MMS + SMM)

+ 0.25P(SMS)

F

B

=

0.5 P(MMS + SMM)

+ 0.50P(SMS)

F

c

=

55

0.25P(SMS)

TABLE I I E f f e c t of D i l u t i o n on the Compositions of Styrene-Methacrylic Anhydride Copolymers when ri=0.26, r = 0.12, r ^ = 5 or 45 moles/£. and r i s v a r i e d 2

3

r

Monomer Concentrations (moles/£. (Anh (S)

c

(moles/£.)

C a l c u l a t e d Mole F r a c t i o n of

5

2.21

2.21

0.316

0.404

0.471

0.493

0.501

5

1.77

1.77

0.301

0.399

0.471

0.495

0.503

5

1.41

1.41

0.285

0.393

0.471

0.497

0.505

5

0.90

0.90

0.268

0.383

0.471

0.499

0.508

45

2.21

2.21

0.208

0.367

0.471

0.503

0.514

45

1.41

1.41

0.199

0.364

0.471

0.503

0.514

45

0.90

0.90

0.194

0.362

0.471

0.504

0.515

The c o e f f i c i e n t s i n the above equations are r e l a t e d t o the p r o b a b i l i t y (aMS = 0.5) that M-S or S-M placements i n the copoly­ mers have meso (erythro) c o n f i g u r a t i o n s . I t was assumed that t h i s p r o b a b i l i t y would a l s o p r e v a i l i n the case of S/MMA copolymers de­ r i v e d from styrene-methacrylic anhydride copolymers. The o p t i m i ­ z a t i o n program STEPIT (19) was then used i n c o n j u n c t i o n with the programs described e a r l i e r i n t h i s paper to f i n d the s e t of r e ­ a c t i v i t y r a t i o s and c y c l i z a t i o n constants that provided the best agreement between observed F$> F^ and Ffi v a l u e s , and those c a l ­ c u l a t e d from monomer feed c o n c e n t r a t i o n s . In a p r e l i m i n a r y o p t i ­ m i z a t i o n , r i and r were maintained equal. T h i s l e d to the r e ­ s u l t s shown i n Table I I I . The o p t i m i z a t i o n was then repeated with r , r and r maintained a t the values shown i n Table I I I and with τ ι and r being evaluated independently. Using ten d i f f e r e n t s t a r t i n g p o i n t s , STEPIT converged on r = 0.184 and r = 0.189 i n a l l cases. I t seems that Smets assumption that r i ^ r i s correct. 3

T

2

c

c

3

x

3

1

3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS

56

WITH CHAIN-RING STRUCTURES

TABLE I I I R e a c t i v i t y R a t i o s and C y c l i z a t i o n Constants Estimated f o r Styrene-Methacrylic Anhydride Copolymerization T h i s work ri

r

3

Γ2

Bevington (13)

Smets (12)

0.19

0.26

0.33

0.11

0.12

0.10

37 moles/£.

45 molesJZ.

7.1 f

r Polymer Temp. Solvent

60° Benzene

60°

36.6°

Benzene

Cyclohexanone

a) These constants have not been c o r r e c t e d f o r the f a c t that two double bonds a r e present i n m e t h a c r y l i c anhydride. F i g u r e 3 and Table I compare the compositions of styrenem e t h a c r y l i c anhydride and styrene/MMA copolymers prepared i n t h i s study with those c a l c u l a t e d from monomer feed c o n c e n t r a t i o n s and the r e a c t i v i t y r a t i o s and c y c l i z a t i o n constants determined i n t h i s study. I t should be remembered that the F contents of the parent copolymers may be high s i n c e some of the copolymers d i d not seem to contain u n c y c l i z e d u n i t s . I t can be seen that the c a l c u l a t e d com­ p o s i t i o n s are i n good agreement with observed compositions f o r polymers with low styrene contents, but that the agreement i s not very good f o r polymers with high styrene contents. In p a r t i c u l a r , c a l c u l a t e d F contents are much higher than observed ones. T h i s suggests that i t may be necessary t o adopt a modified k i n e t i c model to b r i n g everything i n t o agreement, as i s mentioned e a r l i e r i n t h i s paper. In a n a l y z i n g methoxy proton resonance p a t t e r n s of S/MMA co­ polymers we have found i t convenient to c o n s t r u c t HR p l o t s ( 6 ) . These are p l o t s of the l e f t - h a n d p a r t s (L.H.P.) of the f o l l o w i n g equations vs P(SMM4MMS)/P(SMS). u

u

F A - Ρ (MMM) Ρ (SMS)

X P(SMM+MMS) + Y Ρ (SMS)

Ρ (SMS)

Χ' P(SMMfMMS) + Y Ρ (SMS)

£C Ρ (SMS)

f

X" P(SMM+MMS) + Y" "

FXSMS)

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

4.

NEUMANN

AND

Styrene-Methyl methacrylate Copolymers

HARWOOD

57

These equations are based on the assumption that the methoxy proton resonance a s s o c i a t e d with MMM t r i a d s occurs e n t i r e l y i n the Aarea. The slopes and i n t e r c e p t s o f HR p l o t s i n d i c a t e the d i s t r i ­ b u t i o n of (MMS+SMM)- and (SMS)- methoxy proton resonances among the A, Β and C areas. The r e a c t i v i t y r a t i o s determined i n t h i s work are based on the assumption that X = X = 0.5, X" = 0 · , γ = γ» = 0.25 and Y = 0.5. I t was o f i n t e r e s t t o c o n s t r u c t HR p l o t s from the r e s u l t s obtained i n t h i s study to see how w e l l t h i s assumption holds up and access the q u a l i t y o f the f i t obtained by use of the STEPIT o p t i m i z a t i o n r o u t i n e . As can be seen i n F i g u r e 4, the HR p l o t s are l i n e a r . The c o e f f i c i e n t s o f these p l o t s i n d i ­ cate that the methoxy proton resonances can be described by the f o l l o w i n g equations. 1

f

F

A

- Ρ(MMM) + 0.4 0.44

P(SMM-ttlMS) + 0.50 Ρ (SMS)

0.08

P(SMM-ttlMS) + 0.25 Ρ(SMS)

These equations a r e s i m i l a r t o those assumed f o r the r e ­ a c t i v i t y r a t i o determination. In c o n t r a s t t o what has been ob­ served f o r conventional styrene-MMA copolymers, however, these equations i n d i c a t e that a s u b s t a n t i a l p r o p o r t i o n o f the (SMM+MMS)type resonance appears to occur i n the C-area. The p r o p o r t i o n o f methoxy resonance observed i n the C-area, i n f a c t , exceeds Ρ(SMS) by a s u b s t a n t i a l amount f o r many o f the copolymers. T h i s can be due to the assumption o f an inadequate model f o r the copolymeri­ z a t i o n r e a c t i o n , to the use o f i n c o r r e c t r e a c t i v i t y r a t i o s and c y c l i z a t i o n constants f o r the c a l c u l a t i o n s o r t o an inadequate understanding of the methoxy proton resonance p a t t e r n s of S/MMA copolymers. I t i s p o s s i b l e that i n t r a m o l e c u l a r r e a c t i o n s between propagating r a d i c a l s and u n c y c l i z e d m e t h a c r y l i c anhydride u n i t s present on propagating chains r e s u l t i n the formation o f macroc y c l e s . F a i l u r e to account f o r the formation of macrocycles would r e s u l t i n overestimation o f r and r and i n underestimation o f the p r o p o r t i o n s o f MMA u n i t s i n SMS t r i a d s i n the d e r i v e d S/MMA copolymers. T h i s might account f o r the r e s u l t s obtained. An a l t e r n a t e p o s s i b i l i t y i s that a h i g h p r o p o r t i o n (>50%) o f the M-M placements i n the copolymers s t u d i e d i n t h i s work can be expected to have meso placements CI>2,) » whereas only a small p r o p o r t i o n of such placements (^20%) are meso i n conventional S/MMA copolymers. Studies with molecular models (20) have i n d i c a t e d that the methoxy protons on MMA u n i t s centered i n s t r u c t u r e s such as the f o l l o w i n g can experience a p p r e c i a b l e s h i e l d i n g by next nearest styrene u n i t s . f

c

H

c

COOMe

•

„£00CH —

CH r

3

m

I CH

—

3

Η

f

3

r

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

58

POLYMERS

I

!

I

10

I

I

I

WITH

I

1

2 0 3 0 4 0 5 0 Θ 0 %S

CHAIN-RING

70

I

STRUCTURES

I

8090

f

Figure 3. Mole fraction of styrene units in styrene-methyl methacrylate copoly­ mers %S (S/MMA) derived from styrene-methacrylic anhydride copolymers, as a function of the molar percentage of styrene (% S ) in the monomer mixture used to prepare the styrene-methacrylic anhydride copolymers. The solid line was calcu­ lated using η = r = 0.19, r = 0.11, r = 37 and r ' = 7.7. Key: O , 60°C polymerization; and • , 40° C polymerization. f

s

t

c

0

50 f -

10

2

0

3

0

4 f

0

5

0

Θ

0

70

8 0 9 0

(SMM+MMS) f

SMS

Figure 4. HR-Plots of methoxy proton resonance data for styrene-methyl meth­ acrylate copolymers derived from styrene-methacrylic anhydride copolymers pre­ pared at 60°C. Key: O, (F -P(MMM))/P(SMS) vs. P(SMM + MMS)/P(SMS); V, F /P(CMS) vs. PfSMM + MMS)/P(SMS); Q F /P(SMS) vs. P(SMM + MMS)P(SMS). A

B

C

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

4.

NEUMANN

AND

HARWOOD

Styrene-Methyl Methacrylate Copolymers

59

Should the resonance of such protons occur in the C-area, the apparent observation of (SMM+MMS) resonance in this area in the present study, might be explained. Thus, the concentration of such structures can be expected to be higher in S/MMA copolymers derived from styrene-methacrylic anhydride copolymers than in con­ ventional S/MMA copolymers. We hope to do additional work on this problem using 300 MHzH-NMR and *C-NMR spectroscopies. 1

3

Conclusion Procedures for converting styrene-methacrylic anhydride co­ polymers into styrene-methacrylic acid and styrene-methyl meth­ acrylate copolymers have been developed. Mathematical procedures and appropriate compute lating the compositions and of products derived from them. By fitting the compositions and methoxy proton resonance patterns of styrene-MMA copolymers derived from styrene-methacrylic anhydride copolymers to composi­ tions and methoxy proton resonance patterns calculated using these computation methods, reactivity ratios and cyclization constants for the styrene-methacrylic anhydride copolymerization system were derived. The methoxy proton resonance patterns of the derived copolymers indicate that a higher proportion of this resonance occurs in the highest field methoxy proton resonance area (C) than would be expected based on our present understanding of these patterns. This point merits further investigation. Acknowledgement The authors are indebted to the National Science Foundation for partial support of this study, to Dr. Ronald E. Bockrath for helpful discussions, and to Mr. Everett R. Santee for experimental assistance. Literature Cited 1. Miller, W.L.; Brey, Jr., W.S.; Butler, G.B. J. Polym. Sci. 1961, 54, 329. 2. Hwa, J.C.H. J. Polym. Sci. 1962, 60, S12. 3. Smets, G.; Hous, P.; Deval, N. J. Polym. Sci., Part A 1964, 2, 4825. 4. Gibbs, W.E.; Murray, J.T. J. Polym. Sci. 1962, 58, 1211. 5. Thall, E., Ph.D. Dissertation, University of Akron, 1972. 6. Harwood, H.J.; Ritchey, W.M. J. Polym. Sci., Part Β 1965, 3, 419. 7. Ito, K.; Yamashita, Y. J. Polym. Sci., Part Β 1965, 3, 625. 8. Gibbs, W.E.; McHenry, A.J. J. Polym. Sci., Part A 1964, 2, 5277.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS

60

9. 10. 11. 12. 13. 14. 15. 16.

17. 18. 19. 20.

WITH

CHAIN-RING

STRUCTURES

Roovers, J.; Smets, G. Makromol. Chem. 1963, 60, 89. Hwa, J.C.H.; Miller, L. J. Polym. Sci. 1961, 55, 197. Aso, C. J. Polym. Sci. 1959, 39, 475. Smets, G.; Deval, N; Hous, P. J. Polym. Sci., Part A 1964, 2, 4835. Baines, F.C.; Bevington, J.C. Polymer 1970, 11, 647. British Patent 538,319 (July 29, 1941); Chem. Abstr., 36, 1619 (1942). Yakubovich, Y.; Muler, J.; Bayelevski, D. J. Gen. Chem. (U.S.S.R) 1960, 30, 1299. Harwood, H.J.; Kodaira, Y.; Neumann, D.L. in "Computers in Polymer Science", ed. by Mattson, J.S., Mark, Jr., H.B., and MacDonald, Jr., H.C., M. Dekker, Inc., New York, N.Y., 1977, Chapter 2. Price, F.P. J. Chem Kodaira, Y.; Harwood Plast. Chem., Preprints, 1981, 45, 305. Chandler, J. P. Subroutine STEPIT, Program Number 66.1, Quantum Chemistry Program Exchange, Indiana University, Bloomington, Indiana Bockrath, R.E. Ph.D. Dissertation, University of Akron, 1971.

RECEIVED February 1, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

5 N,N-Dimethyl-3,4-Dimethylenepyrrolidinium Bromide Polymer R A P H A E L M. OTTENBRITE Virginia Commonwealth University, Department of Chemistry, Richmond, V A 23284

The formatio polymerization processes had led to many interesting and useful polymers. Aqueous solution of N,N­ -dimethyl-3,4-dimethylenepyrrolidinium bromide were found to polymerize spontaneously at 60°C. The polymerization occurs by a 1,4-addition and the polymer product has properties very similar to that of poly(N,N-dimethyldiallylammonium chloride). High molecular weight polymers were obtained with monomer concentrations of 40-50%. Higher monomer concentrations yielded insoluble gels. Polyelectrolytes are one of the most interesting and u t i l i z able polymer materials presently under development. These water soluble polymers may be classified into three main groups: nonionic polyelectrolytes, such as polyols, polyethers and polyamides; anionic polyelectrolytes, such as carboxylates, sulfonates, and phosphates; and cationic polyelectrolytes, such as ammonium, quaternary amines, sulfoniums and phosphoniums (1). These materials have wide and varied industrial applications. The cationic polyelectrolytes,in particular, are versatile and useful materials with applications being found in water treatment, waste treatment, preparation of papers, textiles, o i l drilling, plastics and biomedical areas (2). One of the prime environmental objectives is the removal of suspended contaminants from water and waste streams. Water turbidity in nature is the result of colloidal clay dispersion and the color is from decayed wood and leaves (tannins and lignins) and organic soil matter. In addition to these contaminants, there are viruses, algae, bacteria, metal oxides, oils and other pollutants. In recent years, synthetic organic polyelectrolyes, in particular the cationic polymers, have been used very effectively in water treatment (3). These polyelectrolytes are high 0097-6156/82/0195-0061 $06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

62

POLYMERS

WITH

CHAIN-RING

STRUCTURES

performance m a t e r i a l s and can be used i n very low dosages. The amount of polymer used i s only 2 or 3 percent of the amount of the i n o r g a n i c m a t e r i a l s necessary f o r c o a g u l a t i o n and f l o c c u l a t i o n . T h i s r e s u l t s i n reduced bulk of treatment chemicals, i n creased c a p a c i t y of the p l a n t and l e s s b u l k f o r d i s p o s a l a f t e r treatment. Another b e n e f i t i s b e t t e r sludge c o n d i t i o n i n g and caking which r e s u l t s i n e a s i e r dewatering and the f i l t e r runs c l e a n e r , longer and more e f f i c i e n t l y than with i n o r g a n i c materials. P o l y e l e c t r o l y t e s are much more e f f e c t i v e i n f l o c c u l a t i o n than i n o r g a n i c polymetal hydrate complexes because t h e i r e f f e c t i v e chain l e n g t h i s much longer. Consequently, b r i d g i n g between p a r t i c l e s can occur more r e a d i l y and r e s u l t i n more m i c r o f l o c s . C y c l i c Quaternary Ammonium Polymers Attempts have bee "ionene" c a t i o n i c p o l y e l e c t r o l y t e s without success (the highest molecular weight was about 40,000 (4, _5, 6 ) . In f a c t , the molec u l a r weight was reported to be almost i n v e r s e l y p r o p o r t i o n a l to the charge d e n s i t y of the polymer Ç5). B u t l e r (7), however, has developed one of the most i n t e r e s t ing and e f f e c t i v e i n d u s t r i a l c a t i o n i c polymers by f r e e r a d i c a l polymerization of Ν,Ν-dimethyldiallylammonium c h l o r i d e (DMDAC). The polymerization process i n v o l v e s an i n t r a - i n t e r m o l e c u l a r c y c l o p o l y m e r i z a t i o n which r e s u l t s i n a polymer which was o r i g i ­ n a l l y reported to have a 6-membered p i p e r i d i n i u m r i n g as a r e ­ peating u n i t i n the polymer chain (8).

CH

CH

3

I

3

1

However, two c y c l i c s t r u c t u r e s are p o s s i b l e : a 6-membered r i n g 3^ and 5-membered r i n g j4. The 6-membered r i n g s t r u c t u r e i s thermodynamically more s t a b l e than the 5-membered due to r e l i e f of 1 , 2 - i n t e r a c t i o n s i n the c h a i r conformation. The six-membered r i n g a l s o g i v e s r i s e to a 2° r a d i c a l i n the propagation sequence whereas the 5-membered-ring gives a l e s s s t a b l e 1° r a d i c a l . The 6-membered r i n g i s u s u a l l y regarded as the thermodynamic pro­ duct because of i t s greater apparent s t a b i l i t y , and the 5-member­ ed r i n g i s regarded as the k i n e t i c product.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

5.

OTTENBRITE

N,N^imethyl-3,4-Dimethylenepynolidinium Bromide

R-CH

2

CH, 3 CH

0

CH, 3

63

3

R-CH

1

4

Subsequently, s e v e r a r i e d out t o determine whether 1,6-diene systems undergo c y c l i z a t i o n i n an i n t r a m o l e c u l a r mode by forming a 5-membered r i n g or 6-membered r i n g ( 9 ) . Since polymer systems a r e s t r u c t u r a l l y d i f f i c u l t t o evaluate some very i n t e r e s t i n g s t u d i e s on monomer substrates were c a r r i e d out by Brace (10), J u l i a (11), Solomon (12), Lancaster (13) , and O t t e n b r i t e (9)· These s t u d i e s have shown r a d i c a l a d d i t i o n t o a 1,6-diene system occurs r e a d i l y i n an i n t r a m o l e c u l a r mode t o p r e f e r e n t i a l l y form a 5-membered r i n g . There a r e s e v e r a l f a c t o r s that i n f l u e n c e t h i s c y c l i z a t i o n process: (a) the r e l a t i v e conformational s t a b i l i t y of a 6-membered r i n g system over a 5-membered r i n g system (9, 10^, J U , J^2, 14), (b) s t e r i c i n f l u e n c e s o f 2,5-substituents (12), (c) r a d i c a l s t a b i l i z a t i o n of the i n i t i a l s i t e (11) and (d) e l e c t r o n d e n s i t y d i f f e r e n c e s between C-5 and C-6 causing coulombic i n t e r a c t i o n s · Although s e v e r a l systems have been evaluated t o determine the s t r u c t u r e o f the r i n g formed i n c y c l o p o l y m e r i z a t i o n , v e r y l i t t l e work has been reported on the o r i g i n a l cyclopolymer r e ported by B u t l e r (7) that was obtained from N , N - d i m e t h y l d i a l l y l ammonium bromide or the c h l o r i d e . Consequently, we undertook a study o f a five-membered quaternary ammonium polymer, poly(1,1, 3,4-tetramethyl-3-pyrrolinium bromide) as a model system. N,Ndlmethyl-3,4-dimethylenepyrrolidinium bromide ( 6 0 was prepared by r e a c t i n g dimethylamine with 2,3-bis(bromomethyl)-l,3-butadiene ( 5 ) . I n a d d i t i o n t o the bromide s a l t (6), the i o d i d e s a l t was a l s o prepared by r e a c t i n g 2,3-bis(bromomethyl)-l,3-butadiene

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

64

POLYMERS

WITH CHAIN-RING STRUCTURES

with methylamine i n a c e t o n i t r i l e to form a s o l u t i o n of N-methyl3,4-dimethylene p y r r o l i d i n e J3. Methyl i o d i d e was added to a s o l u t i o n of J3 t o form the i o d i d e s a l t 9^. Aqueous s o l u t i o n s of the e x o c y c l i c diene 6^ r e a d i l y p o l y -

CH

CH

3

3

9 merized to form the c a t i o n i c p o l y e l e c t r o l y t e c o n t a i n i n g a 3p y r r o l i n i u m r i n g 6^ as part of the polymer c h a i n . The NMR spectra

6

10

of the polymer obtained from 6_ a r e c o n s i s t e n t with the proposed s t r u c t u r e 10 which would r e s u l t from 1,4-polymerization of the diene system. ^ We conducted a C NMR study (9) o f a 6-membered quaternary ammonium monomer model, a 5-membered quaternary ammonium model (a hydrogen reduced d e r i v a t i v e of N,N,3,4-tetramethyl-3-pyrrolidinium bromide) and poly(N,N-dimethyldiallylammonium c h l o r i d e ) . The s p e c t r a l data i n d i c a t e d that poly(N,N-dimethyldiallylammonium c h l o r i d e ) i s composed o f 5-membered r i n g s r a t h e r than the 6-membered system. A s i m i l a r study was c a r r i e d out by Lancaster e t . a l . (13) and analogous r e s u l t s were obtained. Subsequently, we were a b l e to completely reduce the unsaturated 5-membered poly(N,N-dimethyl-3-pyrrolidinium bromide) t o y i e l d completely saturated 5-membered r i n g s . The l ^ C NMR of t h i s reduced polymer m a t e r i a l gave a spectrum that was the same as that obtained from poly(N,N-dimethyldiallylammonium c h l o r i d e ) which u n e q u i v o c a l l y shows that the c y c l o p o l y m e r i z a t i o n produces 3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

5.

OTTENBRiTE

N,N-Dimethyl-3,4-Dimethylenepyrrolidinium Bromide

65

e x c l u s i v e l y 5-membered r i n g s along the polymer backbone i n a predominently c i s c o n f i g u r a t i o n ( 9 ) . P o l y m e r i z a t i o n Studies of inium Bromide

N,N-dimethyl-3,4-dimethylenepyrrolid-

I t was found that N,N-dimethyl-3,4-dimethylenepyrrolidinium bromide undergoes spontaneous p o l y m e r i z a t i o n i n aqueous s o l u t i o n s when the c o n c e n t r a t i o n of monomer i s greater than 10% a t 60°C. Conversion s t u d i e s by NMR show that r a t e and degree of con­ v e r s i o n i n c r e a s e with i n c r e a s i n g c o n c e n t r a t i o n (Table I ) . Table I :

No.

Concentration Study on the P o l y m e r i z a t i o n of Ν,ΝDlmethyl-3,4-Dimethylenepyrrolidinium Bromide

Monomer Concentration

Temperature °C

%

a) b)

Time hr

Yield

%

1

10

60

24

45

2

20

60

24

81

3

40

60

5

100

4

50

60

5

5

60

60

5

Viscosity of polymer 1.37 1.70

b

3.90

100

b

4.05

100

b

Gel

Measured i n 2.0M KBr at 30°C. Contains 5-10% of a dimer formed by a s e l f D i e l s - A l d e r Reaction

At low monomer concentrations (10-20%), the p o l y m e r i z a t i o n mix­ ture a f t e r 24 h r s contained polymer 45% and 81%, r e s p e c t i v e l y , and unreacted monomer. At higher c o n c e n t r a t i o n (>40%), a l l the monomer appeared t o have been t o t a l l y reacted i n l e s s than 5 h r s . The r e a c t i o n mixture, however, was found to c o n t a i n 5-10% of a dimer 11 formed by a s e l f D i e l s - A l d e r r e a c t i o n of the monomer.

CH

ΓΙΟΠΟ CH

3

CH

2Br®

2

U I t was observed that the molecular weight of the polymer i n ­ creased s i g n i f i c a n t l y with increased monomer c o n c e n t r a t i o n . For example, at 10% monomer c o n c e n t r a t i o n , the i n t r i n s i c v i s c o s i t y was 1.37 d l / g while the v i s c o s i t y was 4.05 d l / g at 50% monomer c o n c e n t r a t i o n . At 60% monomer c o n c e n t r a t i o n , an i n s o l u b l e g e l

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

66

POLYMERS

WITH

CHAIN-RING

STRUCTURES

was formed which appeared t o have c o n s i d e r a b l e c r o s s l i n k i n g . I t was a l s o observed from r a t e conversion s t u d i e s that the r a t e s of p o l y m e r i z a t i o n were l a r g e r a t higher c o n c e n t r a t i o n of monomer (Figure 1)· The spontaneous p o l y m e r i z a t i o n i n aqueous s o l u t i o n e x p e r i enced i n t h i s polymer system i s not unique to quarternary systems. Salomone (15) e x t e n s i v e l y studied the spontaneous p o l y m e r i z a t i o n of 4 - v i n y l p y r i d i n i u m s a l t s . Although there are s e v e r a l s i m i l a r i t i e s i n the two systems, i t appears that the i n i t i a t i n g species may be d i f f e r e n t and w i l l be the subject of f u t u r e s t u d i e s . For example, 20% monomer s o l u t i o n s i n methanol at 60° f o r 24 h r s showed no p o l y m e r i z a t i o n thus i n d i c a t i n g that the spontaneous I n i t i a t i o n may be dependent on the aqueous media* Other i n i t i a t o r s (Table II) have v a r y i n g e f f e c t s ( F i g u r e 2 ) ; £ - b u t y l hydroperoxide Table I I :

No.

Conversion Dimethyl-3,4-dimethylenepyrrolidinium

Monomer Concentration %

1

20

2

20

Initiator % of Monomer

Time hr

Conversion %

60

24

93

8

60

24

77

8

25

24

50

Temperature °C

None (NH ) S 0 4

2

2

Bromide

1% 3

20

(NH ) S 0 4

2

2

1% 4

20

t-Butyl Hydroperox i d e 1%

60

5

100

5

20

None i n methanol

60

24

0

produced 100% conversion i n 5 h r s , while ammonium p e r s u l f a t e appeared to i n h i b i t the process with only 77% conversion a f t e r 24 h r s . The l a t t e r r e s u l t may be due t o bromide i o n o x i d a t i o n by the p e r s u l f a t e ions t o generate bromine which can a c t as an i n h i b i t o r . A s i m i l a r o b s e r v a t i o n by Negi and coworkers (16) was made with diallyldimethylammonium bromide s a l t which does not polymerize as r e a d i l y i n the presence of ammonium p e r s u l f a t e as d i d the corresponding c h l o r i d e s a l t . The a d d i t i o n of other s a l t s t o the p o l y m e r i z a t i o n system was a l s o evaluated F i g u r e 3. Ammonium bromide and sodium bromide showed a s l i g h t i n c r e a s e i n conversion r a t e which was a t t r i b u t e d to an i n c r e a s e i n the d i e l e c t r i c constant o f media. I t was noted that the ammonium i o n does not appear to have any e f f e c t on the i n i t i a t i o n process. A l a r g e r a t e i n c r e a s e with 10%

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

5. OTTENBRiTE

N,N-Dimethyl-3,4-Dimethylenepyrrolidinium Bromide

J

1

1

2

I

I

I

L

3

4

5

6

67

TIME (hrs)

Figure 1. Effect of monomer concentration on the rate of polymerization of N,Ndimethyl-3,4-dimethylenepyrrolidinium bromide.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING

68

loo

I—

80

L.

STRUCTURES

φ (0 D 60 u

% ο c ο s Ο Φ 40 Ο

20

Time

(hrs)

Figure 2. Influence of initiators and concentration on the rate of polymerization ofΝ,N-dimethyl-3,4-dimethylenepyrrolidinium bromide. Key: • , 40% monomer; O, 20% monomer with t-butyI hydroperoxide; Φ,20% monomer; A , 20% monomer with ammonium persulfate.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

OTTENBRITE

*N,N-Dimethyl-3,4-Dimethylenepyrrolidinium Bromide

2.5% EDTA

TIME

(hrs)

Figure 3. Effect of additives on the rate of polymerization of 0.5M N,N-dimethyl3,4-dimethylenepyrrolidinium bromide.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING

STRUCTURES

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

5. OTTENBRiTE

N,N-D/W///y/-3,4-Dimethylenepyrrolidinium

Bromide

71

NaCl was experienced. This observation was similar to the find­ ings (16) in the case of diallyldimethylammonium chloride salt which polymerizes more readily than the bromide salt. Another large increase in rate of conversion was obtained with 2.5% EDTA. The reason for this great increase is not evident but was also observed for the diallyldimethylammonium chloride polymeri­ zation by Hoover (17). Initial studies showed that this polymer has the potential of being an excellent flocculating agent. Performance evalua­ tions were made by comparing flocculating data to commerical Cat-Floe (18) on a 50 ppm Montmorillonite clay suspension using the method of Black and Vilaret (19). Floe times and residual turbilities of low molecule weight samples (η = 1.35 and 1.75) were comparable to Cat-Floc It is anticipated the higher molecular weight polymer will giv tests (21,20) to determin mance was better than those obtained with Cat-Floc. Acknowledgement I wish to thank Dr. Rodney Meyers for his efforts in these studies as well as the cooperation of the personnel at Calgon Corporation. I also wish to thank the National Science Founda­ tion for support in part for this study. Literature Cited 1. Eisenberg, A. and Hoover, M.F., "Ion Containing Polymers", American Chemical Society Publications, Washington, D.C., 1972. 2. Rembaum, A. and Selegny, Z., "Polyelectrolytes and Their Applications", Vol. 1 and 2, D. Reidel Publishing Company, Holland (1975). 3. Ottenbrite, R.M. and Ryan, W.S., I & EC Prod. Res. and Devel., 19, 528 (1980). 4. Ottenbrite, R.M. and Myers, G.R., J. Poly. Sci., 11, 1443 (1973). 5. Noguchi, H. and Rembaum, Α., J. Polym. Sci. B, 1, 385 (1969). 6. Rembaum, Α., Baumgartnes, W. and Eisenberg, W., J. Polym. Sci. B, 6, 159 (1968). 7. Butler, G.B. and Ingley, F., J. Amer. Chem. Soc., 73, 895 (1951); Butler, G.B. and Angelo, R.J., ibid., 79, 3128 (1957); Butler, G.B., U.S. Patent 3,288,770, 1966. 8. Butler, G.B., Gropp, A.H., Angelo, R.J., Husa, W.J. and Jorolan, E.P., 5th Quaterly Report. Atomic Energy Commis­ sion Contract AT(40-1)-1353 (1953). 9. Ottenbrite, R.M. and Shillady, D.D., IUPAC Symposia: Quaternary Ammonium and Amine Polymers, Goethals, E.J., Ed., p. 143 Pergamon Press, New York, 1980.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS

72

WITH CHAIN-RING STRUCTURES

10. Brace, N.O., J. Poly. Sci., 8, 2091 (1970); J. 0rg. Chem., 44, 212 (1978). 11. Julia, Μ., Chem. Eng. News, 44, 100 (1966); Julia, M. and Manny, M., Bull. Soc. Chem., 434 (1966). 12. Hawthorne, D.G. and Solomon, D.H., J. Macromol. Sci. Chem., A10, 923 (1976). Beckwith, A.J., Ong, A.K. and Solomon, D.H., J. Macromol. Sci. Chem., A9, 115 (1975); ibid., A9, 125 (1975); Hawthorne, D.G., Johns, S., Solomon, D. and Willings, R., Chem. Commun., 982 (1975). 13. Lancaster, J., Baccei, L. and Panzer, H., Polymer Letters, 14, 549 (1976). 14. Smith, T.W. and Butler, G.B., J. Org. Chem., 43, 6 (1978). 15. Salomone, J. 16. Negi, Y., Haradu 1951 (1967). 17. Boothe, J.E., Flock, H.G. and Hoover, M.F. 18. Commercially known as Cat-Floc produced and marketed by Calgon Corporation, Pittsburg, Pa. 19. Black, A.P. and Vileret, M.R., Jour. A.W.W.A., 61, 209 (1969). 20. Water Pollution Control Federation Manual Practice No. 20, "Sludge Dewatering", 3900 Wisconsin Avenue, Washington, D.C. 21. Calgon Technical Information Bullentin No. 12-1034 "Buchner Funnel Test", 1968. RECEIVED February 17, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

6 Radical Cyclopolymerization of Divinyl Formal: Polymerization Conditions and Polymer Structure MITSUO TSUKINO Kitakyushu Technical College, Department of Chemical Engineering, Kokura-minami, Kitakyushu 803, Japan TOYOKI KUNITAKE Kyushu University, Department of Organic Synthesis, Faculty of Engineering, Fukuoka 812, Japan

Radical polymerizatio conducted in benzen polyme examined byH- and C-NMR spectroscopy. The polymer contains the cis-dioxolane ring as the major structure, along with the trans-ring and the branched structure. The major structures are connected in the meso and racemic fashions. The content of the minor structures becomes negligible by lowering polymerization temperature and by increasing monomer concentration. The unsaturated unit and the six-membered unit are not formed under any condition. 1

13

We have been conducting detailed structural studies on the cyclopolymers of several unconjugated dienes. Radical cyclopolymerization of divinyl ether had been known to give polymers with the unsaturated monocyclic unit and the bicyclic unit(j^, 2). Our initial C-NMR study indicated that the polymer was composed of the five-membered monocyclic unit with the pendent unsaturation and the bicyclic unit with the bicyclo[3,3.0]octane skeleton(3.) . According to the stereochemistry of the polymer established by more recent NMR examinât ion (4), the polymerization process was shown to be highly stereoselective. 13

or

—C ;r*CH2

0097-6156/82/0195-0073$06.00/0 © 1982 American Chemical Society In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

74

POLYMERS

WITH CHAIN-RING

STRUCTURES

Similar studies were performed for the radical polymers of cis-propenyl vinyl ether and 2-methylpropenyl v i n y l ether, with the conclusion that the polymer structures were basically the same as that of poly(divinyl ether)(5).

cis-propenyl vinyl ether

2-methylpropenyl vinyl ether

Divinyl acetals are also known to give soluble cyclopolymers by radical polymerization. Although the polymer structure had been studied by a variet (j6-9), the results wer obtained as to the stereochemistry. Our C-NMR methodology was thus applied to polymers of divinyl acetal and i t s derivatives (acetaldehyde divinyl acetal and acetone divinyl acetal)· Comparison of C-NMR spectra of the polymers with those of 1,3dioxolanes and 1,3-dioxanes which are model compounds of the cyclic units indicates that these polymers have essentially the same structure(10). The propagation process of these monomers i s shown i n Scheme I with divinyl formal as an example. The i n t r a molecular cyclization produces cis-closed five-membered cyclic radical I predominantly. The radical either reacts with monomer or abstracts hydrogen from the neighboring exocyclic methylene. The newly-formed radical propagates subsequently to produce branched unit III. On the other hand, NMR evidence indicates the absence of the uncyclized structure and the trans-closed rings IV and V. Furthermore, i t i s indicated that the meso and racemic modes exist i n equal amounts for the connection between the major structure I I . Following these previous results, we investigated i n this study the influence of the polymerization conditions(monomer concentration and polymerization temperature) on the structure of poly(divinyl formal). 13

Experimental Materials. Divinyl formal was prepared as described before (10). Azobis(isobutyronitrile)(AIBN) was recrystallized from methanol. Benzene and methanol were purified by the conventional procedure. Polymerization. The polymerization was conducted i n benzene with AIBN i n i t i a t o r at 50 and 70 C. The i n i t i a t i o n was accelerated at 10 and 30°C by irradiation with a high-pressure Hg lamp. Required amounts of divinyl formal, benzene and AIBN were placed i n ampoules, subjected to the freeze-pump-thaw cycle, and the e

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

6.

TSUKINO

AND

KUNITAKE

Cyclopoly'merization of Divinyl Formal

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

75

POLYMERS WITH CHAIN-RING STRUCTURES

76

ampoules s e a l e d . The polymers were p r e c i p i t a t e d by methanol, r e p r e c i p i t a t e d from benzene and methanol, and d r i e d . They were f r e e z e - d r i e d from benzene, when necessary. M i s c e l l a n e o u s . NMR s p e c t r a o f 1,3-dioxolanes were obtained with a V a r i a n A-60 spectrometer. H- and C-NMR s p e c t r a o f the polymers were obtained with a JEOL FX-100 spectrometer. The molecular weight was determined by g e l permeation chromatography (Toyo Soda HLC-802UR) u s i n g monodisperse p o l y s t y r e n e as r e f e r e n c e . 1

13

Results and D i s c u s s i o n I t was p r e v i o u s l y confirmed that the six-membered r i n g and the unsaturated u n i t were not present i n the polymer(10). The five-membered r i n g u n i F i g u r e 1. S t r u c t u r e and Β i s the branched c i s - c l o s e d r i n g . C and D are the t r a n s c l o s e d r i n g s i n the main c h a i n and i n the s i d e c h a i n , r e s p e c t i v e ­ ly. Ε and F are the c h a i n end r i n g s with the c i s and trans stereochemistries. F i g u r e 2 shows a *H-NMR spectrum of the polymer obtained at low monomer c o n c e n t r a t i o n and high p o l y m e r i z a t i o n temperature. The carbon chemical s h i f t s o f the t r a n s r i n g s are c l o s e t o those of s t r u c t u r e B, and the a c e t a l carbons o f s t r u c t u r e s A t o Ε i n F i g u r e 1 possess almost the same chemical s h i f t . From these data we t e n t a t i v e l y concluded i n our previous study that the trans r i n g u n i t s were absent(10). However, the stereochemical d i f f e r e n c e o f the r i n g i s c l e a r l y r e f l e c t e d i n the chemical s h i f t of the a c e t a l hydrogen i n the H-NMR spectrum o f improved r e s o l u t i o n ( F i g u r e 2 ) . The peak assignment i s performed on the b a s i s of the chemical s h i f t o f 1,3-dioxolanes: peaks a t c a . 1 ppm are a t t r i b u t e d t o the methyl proton of s t r u c t u r e s Β and D, and peaks at 1.5-2.0 ppm a t t r i b u t e d t o the e x o c y c l i c methylene proton o f s t r u c t u r e s A and C. The molecular weight o f t h i s polymer i s r e l a t i v e l y small(MW « 2800), and a methyl proton peak of t h e i n i t i a t o r fragment i s observable a t 1.4 ppm. The peaks o f the r i n g methine protons are l o c a t e d a t 3.3-4.3 ppm, and the peaks of the a c e t a l methylene proton are s e p a r a t e l y found a t 4.5-5.0 ppm, i n correspondence t o the s t r u c t u r e s o f F i g u r e 1. The t o t a l amount of the t r a n s r i n g u n i t ( C + D + F) i s 20 %, as estimated from the r e l a t i v e peak area o f the a c e t a l proton. F i g u r e 3 gives C-NMR s p e c t r a of the polymer prepared a t 70°C w i t h d i f f e r e n t monomer c o n c e n t r a t i o n s . These s p e c t r a are assigned as d e s c r i b e d b e f o r e ( l O ) by r e f e r r i n g t o C-NMR data o f 1,3-dioxolanes. In F i g u r e 3a, a peak a t 14 ppm suggests the presence of the methyl carbon o f s t r u c t u r e s Β and E. Peaks a t 25 ppm are a s c r i b e d t o the e x o c y c l i c methylene carbon of s t r u c ­ tures A and E, and they are s p l i t due t o the two modes of r i n g connection(meso and racemic). The methine carbon peaks are l o c a t e d a t 72-82 ppm. The a c e t a l carbon peak of a l l the r i n g 1

13

13

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

6.

Cyclopolymerization of Divinyl Formal

TSUKINO A N D KUNITAKE

-H C CH 2

v

r

-CH-

77

-H C CH 2

V

2

Β

"CH-

Figure 1.

-H2ÎXPH3

-KACH3

Conceivable five-membered ring units for poly(divinyl formal).

ABE(cis-anti)

//

A RF

(cis-syn)

3 2 ppm from TMS Figure 2.

*H NMR spectrum of polyfdivinyl formal). Table I, run 3:3 w/v % in d -DMSO at 150°C; accumulation, 32 scans. 8

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING STRUCTURES

78

(W

(a) B,E C.E

80

60 ppm

40 from

20

TMS

13

Figure 3. C NMR spectra of poly (divinyl formal). Key: a, Table I, run 3, 28 wt % in C D at 75°C, accumulation, 2000 scans; and b, Table I, run 4, 28 wt % in C D at 75°C, accumulation, 1600 scans. 6

6

6

e

Table I. Radical Polymerization of Divinyl Formal Run

Monomer mol/1

1 2 3 4

2.5 2.5 1.0 5.0

AIBN mol/1 b

0.1 > 0.02 0.02 0.02

0

Temp C

Time hr

Conversion %

M η

10 70 70 70

8.0 1.5 6.0 0.75

8.6 8.1 8.6 8.6

5.500 8,100 2,800 20,000

e

a. i n benzene, b. irradiated with a high-pressure Hg lamp

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

6.

TSUKINO

AND

KUNITAKE

Cyclopolymerization of Divinyl Formal

79

structures(A to F) i s at 93.6 ppm. Thus, the branched structure and the trans rings are included i n the polymer apart from the main structure(A), when the monomer concentration i s low. In contrast, the formation of the minor structures are suppressed by conducting polymerization at higher monomer concentrations, as shown by Figure 3b. The fraction of structure A i s estimated from the relative peak area of the acetal carbon (total structures) and the ring methine carbon at 77-78 ppm (structure A), by assuming that NOE's are the same for these peaks. At 70 C, the fraction of A increased from 47 to 78 % upon increase i n the monomer concentration from 1.0 to 5.0 mol/1. Figure 4 i s a H-NMR spectrum of the polymer obtained under the polymerization conditions of relatively low monomer concentration and low polymerization temperature. The formation of structures other than A trans rings(C + D + F) i Figure 5 compares C-NMR spectra of the polymers prepared at different temperatures. The main structure A becomes predominant at a low polymerization temperature as shown i n Figure 5a, but the content of the other structures, particularly the branched c i s ring B, increases at a higher temperature(Figure 5b). The fraction of structure A increased from 66 to 89 % by lowering the polymerization temperature from 70 to 10°C at a fixed monomer concentration of 2.5 mol/1. The mode of connection of the main structure i s constant (meso: racemic » 1:1), i n spite of the change i n the polymerization conditions. The equal amounts of the meso and racemic connections might be randomly distributed. It i s interesting, however, that the sequence of type c appears least s t e r i c a l l y demanding among the four types of the connections on the basis of the CPK molecular model. (a) . . . r r r r r r r r . . . e

1

13

(b)

· · . mmmmmimnm. · ·

(c) (d)

··.mmrrmmrr.·· • · .mrmrmrmr. · ·

In conclusion, the structure of poly(divinyl formal) was shown to vary with the polymerization conditions (Table I ) . It i s expected that highly stereoregular polymers are obtainable by selecting proper polymerization comditions. These results w i l l be described elsewhere, together with the kinetic analysis of the cyclopolymerization process.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING

80

STRUCTURES

A A 1

J

1

1

I

I

L

5

4

3

2

1

0

ppm

Figure 4.

from

TMS

*H NMR spectra of polyfdivinyl formal) from Table I, run 1: 3 w/v in de-DMSO at 150°C; accumulation, 16 scans.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

%

6.

TSUKINO

AND KUNITAKE

Cyclopolymerization of Divinyl Formal

13

81

Figure 5. C NMR spectra of polyfdivinyl formal). Key: a, Table I, run 1, 28 wt % in C D at 75°C, accumulation, 2500 scans; and b, Table I, run 2, 28 wt % in C D at 75°C; accumulation, 3000 scans. 6

e

e

6

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

82

POLYMERS

WITH

CHAIN-RING STRUCTURES

Literature Cited 1. Aso, C.; Ushio, S. Makromol Chem. 1967, 100, 100. 2. Guaita, M,; Camino, C.; Trossarelli, L. ibid. 1970, 131, 237. 3. Kunitake, T.; Tsukino, M. ibid. 1976, 177, 303. 4. Tsukino, M.; Kunitake, T. Macromolecules 1979, 12, 387. 5. Tsukino, M.; Kunitake, T. Polym. J. 1981,13,657. 6. Matsoyan, S. G. J. Polym. Sci. 1961, 52, 189. 7. Minoura, Y.; Mitoh, M. ibid. 1965, A-3, 2149. 8. Aso, C.; Kunitake, T.; Ando, S. J. Macromol. Sci. Chem. 1971, A5, 167. 9. Aso, C.; Kunitake, T.; Tsutsumi, F. Kogyo Kagaku Zasshi 1967, 70, 2043. 10. Tsukino, M.; Kunitake, T. Polym. J. 1979, 11, 437. RECEIVED March 8,

1982

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

7 Divinyl Ether-Maleic Anhydride Copolymer and Its Derivatives: Toxicity and Immunological and Endocytic Behavior 1

L. GROS, H . RINGSDORF, and R. SCHNEE —Institut für Organische Chemie, Universität Mainz, Johann-Joachim-Becher-Weg 20, D-6500 Mainz, Federal Republic of Germany J. B. LLOYD—Biochemistry Research Laboratory, Department of Biological Sciences, University of Keele, Staffs, United Kingdom E . RÜDE, H . U. SCHORLEMMER2, und Immunologie, Universität Mainz

Ö

DIVEMA and some DIVEMA derivatives were synthesized and tested for toxicity and immunological behaviour. Toxicity can be varied by introducing different side groups into parent DIVEMA molecules by polymer analogous reactions. The compounds tested showed mitogenic effects, i.e. they stimulated lymphocyte proliferation. Astonishingly, a DIVEMA-DNP conjugate did not induce the production of DNP-specific antibodies. Our results suggest that this is due to the formation of DNP-specific active suppressor cells. Using serum free culture media, we could show for the f i r s t time that DIVEMA and derivatives stimulate macrophages to release cytotoxic factors into the supernatant. However, no significant release of lytic enzymes was detected. DIVEMA and the derivatives tested failed to stimulate endocytosis by macrophages of 125I-PVP and 198Au (colloidal); higher mol. wt. DIVEMA inhibited pinocytosis. We conclude that the only effect of the compounds tested on macrophages is the release of cytotoxic factors into the supernatant. 1

Current address: Röhm GmbH, Kirschenallee, D-6100 Darmstadt, Federal Republic of Germany.

Current address: Behringwerke, Postfach 1140, D-3550 Marburg/Lahn 1, Federal Republic of Germany.

Current address: Zentrum f. Innere Medizin der Universität, Steinhövelstr. 9, D-7900 Ulm, Federal Republic of Germany. 2

3

0097-6156/82/0195-0083$06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

84

POLYMERS WITH CHAIN-RING STRUCTURES

P h a r m a c o l o g i c a l l y a c t i v e p o l y m e r s , and e s p e c i a l l y p o l y m e r i c a n t i t u m o u r a g e n t s , have b e e n w i d e l y d i s c u s s e d , s y n t h e s i z e d and t e s t e d d u r i n g t h e p a s t decade 2 3 ). Among t h e many a n i o n i c p o l y m e r s t e s t e d f o r p h a r m a c o l o g i c a l a c t i v i t y ( 4 ) , DIVEMA, o r p y r a n c o p o l y m e r , a 1:2 alternating c y c T o c o p o l y m e r o f d i v i n y l - e t h e r a n d mal e i c a n h y d r i d e i n i t s h y d r o l y z e d f o r m ( 5 ) , has b e e n one o f t h e m o s t i n t e n s i v e l y s t u d i e d c o m p o u n d s . DIVEMA has been shown t o h a v e immune s t i m u l a t i n g , a n t i v i r a l a n d a n t i t u m o u r a c t i v i t i e s ( 4 , 6^, 7). These p r o p e r t i e s s u g g e s t e d t h a t DIVEMA mTght be an a p p r o p r i a t e c a r r i e r c a n d i d a t e f o r drug m o l e c u l e s , e s p e c i a l l y f o r a n t i t u mour a g e n t s . T h u s , t h e immunosuppressive folateantagonistsmethotrexate (MTX) ( 8 ) a n d C y t o x a n (cyclop h o s p h a m i d e ) ( 9 , 10 (cf. 3). ~ 9

R

—

T h e r e a r e , h o w e v e r , many u n s o l v e d p r o b l e m s c o n c e r n i n g t o x i c i t y , e n d o c y t i c u p t a k e and i m m u n o g e n i c i t y o f DIVEMA. In o r d e r t o l e a r n more a b o u t t h e s t r u c t u r e d e p e n d e n c y o f t h e s e p r o p e r t i e s , we s y t h e s i z e d some DIVEMA d e r i v a t i v e s a n d i n v e s t i g a t e d DIVEMA a n d t h e new d e r i v a t i v e s with appropriate routine b i o l o g i c a l test systems. Compounds

Tested

DIVEMA s a m p l e s ( 1 a - 1d) w e r e k i n d l y s u p p l i e d by D r . D . B r e s l o w , HERCULES I n c . The s y n t h e s i s o f t h e d e r i v a t i v e s ( 1 1 ) w i l l be p u b l i s h e d e l s e w h e r e . The c o m pounds i n v e s t i g a t e d a r e l i s t e d i n T a b l e I. Acute

Toxicity

of

DIVEMA

a n d two DIVEMA

Derivatives

One d i s a d v a n t a g e o f DIVEMA i s i t s r e l a t i v e l y h i g h t o x i c i t y w h i c h i s m a i n l y c a u s e d by h i g h m o l e c u l a r w e i g h t f r a c t i o n s (7). In an a t t e m p t t o l o w e r t h e t o x i c i t y o f DIVEMA, d e r i v a t i v e s ( 3 ) a n d ( 4 ) were s y n t h e sized. The p y r r o l i d o n e s i d e c h a i n i s known t o be n o n t o x i c e . g . in poly ( v i n y l p y r r o l idone). Incorporation of the d i m e t h y l a m i n o - m o i e t y l e a d s to z w i t t e r i o n i c s t r u c t u r e s ; s u c h s t r u c t u r e s a r e known t o l o w e r t h e t o x i c i t y of the p o l y c a t i o n i c p o l y ( e t h y l e n e i m i n e ) ( 1 2 ) . A c u t e t o x i c i t y o f compounds ( 1 d ) , ( 3 F 7 and ( 4 b ) , a l l o f m o l . w t . 2 4 , 0 0 0 , was t e s t e d i n v i v o . M a l e C 5 7 / B L . 6 m i c e w e r e g i v e n a s i n g l e i . p . d o s e . T a b l e II shows t h e r e s u l t s . T o x i c i t y i s e x p r e s s e d a s LD 5 0 / 2 1 , t h e d o s e l e t h a l f o r 50% o f t h e a n i m a l s by day 21 a f t e r i n j e c t i o n of the polymer.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

7.

GROS E T A L .

Table I .

Behavior of DIVEMA

and DIVEMA

Derivatives

85

Compounds synthesized and t e s t e d w i t h R groups d i s t r i b u t e d between r i n g and chain c a r b o x y l s .

NR

-R

X

MW 4400 11000 16800

la b c d

-OH

2

-ΝΗ-ΙΟΗ,ί,-^^-ΝΟ*

5,3

16 800

3a b

-0-(CH ) -^p

12

16800 24000

4a b

-0-(CH,),-N(CH,)

20

16800 24000

5

-CMCHj^-CHa

4

16 800

a

a

a

COOH

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING

STRUCTURES

Table I I . Acute t o x i c i t y of DIVEMA. and some d e r i v a t i v e s

Substance Nr. 1d

Dose (mg/kg) 300

6/10

400

4/10

300

4/8

400

0/8

300

8/8

400

7/8

500

4/8

600

4/8

700

4/8

300-400

3b

c a . 300

4b

500-600

*LD50/21 - l e t h a l dose f o r 50% of t e s t animals by day 21.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

7.

GROS ET AL.

Behavior of DIVEMA

and DIVEMA

Derivatives

87

The i n t r o d u c t i o n o f t h e p o t e n t i a l l y biocompatible p y r r o l i d o n e u n i t (polymer (3b)) unexpectedly leads to a s l i g h t l y h i g h e r t o x i c i t y , as compared t o t h e s t a r t i n g material (1d). Decrease of the polyanion c h a r a c t e r in the z w i t t e r i o n i c polymer ( 4 b ) , however, substantially lowers toxicity. Effects System.

of

DIVEMA

a n d DIVEMA

Derivatives

on t h e Immune — — —

DIVEMA i s known t o a c t upon d i f f e r e n t t y p e s o f immune c e l l s (J_3) s u c h a s t h e a n t i b o d y p r o d u c i n g Β c e l l s ( b o n e marrow d e r i v e d l y m p h o c y t e s ) ; on T - c e l l s ( t h y m u s p r o c e s s e d l y m p h o c y t e s ) and on m a c r o p h a g e s ( c e l l s which phagocytos nisms o f i n t e r a c t i o n s y s t e m a r e v e r y c o m p l e x . In o r d e r t o i n v e s t i g a t e them, many d i f f e r e n t e x p e r i m e n t a l a p p r o a c h e s c a n be u s e d . Our a p p r o a c h i s b a s e d on t h e f o l l o w i n g questions: - A r e t h e DIVEMA d e r i v a t i v e s m i t o g e n i c , i . e . do t h e y s t i m u l a t e l y m p h o c y t e p r o l i f e r a t i on? - A r e t h e DIVEMA d e r i v a t i v e s a n t i g e n i c , i . e . do t h e y induce production of s p e c i f i c antibodies? - Do DIVEMA d e r i v a t i v e s s t i m u l a t e m a c r o p h a g e s in v i t r o , i . e . do t h e y i n d u c e t h e r e l e a s e o f l y t i c e n z y m e s o r cytotoxic factors? M i t o g e n i c A c t i v i t y o f DIVEMA D e r i v a t i v e s . A f i r s t a p p r o a c h t o t h e e f f e c t s o f a compound on t h e immune system i s to t e s t i t s a b i l i t y to s t i m u l a t e lymphocyte p r o l i f e r a t i o n . An a p p r o p r i a t e t e s t i s t o m e a s u r e t h e i n c o r p o r a t i o n o f H - t h y m i d i n e i n t o DNA o f d i v i d i n g eel 1 s : S u b s t a n c e s ( 1 a ) - ( 1 d ) , ( 3 a ) and ( 4 a ) a r e i n c u ­ bated with s p l e e n c e l l c u l t u r e s of u n t r e a t e d mice i n a s e r u m c o n t a i n i n g c u l t u r e m e d i u m . A d e f i n e d amount o f radioactive H-thymidine is added. A f t e r i n c u b a t i o n , t h e c u l t u r e s a r e deep f r o z e n i n o r d e r t o s t o p c e l l pro­ l i f e r a t i o n a n d DNA i s i s o l a t e d by f i l t r a t i o n through glass f i b r e f i l t e r s . R a d i o a c t i v i t y is counted in a l i q u i d s c i n t i l l a t o r . Control c u l t u r e s are incubated w i t h o u t a n t i g e n ( p o l y m e r ) a d d e d a n d w i t h a known potent mitogen ( C o n c a n a v a l i η A.) A l l substances showed s i g n i f i c a n t m i t o g e n i c acti­ v i t y . H i g h m o l e c u l a r w e i g h t DIVEMA s t i m u l a t e d lympho­ c y t e p r o l i f e r a t i o n a t lower c o n c e n t r a t i o n than the c o r r e s p o n d i n g low m o l e c u l a r w e i g h t s a m p l e s . Derivatives (3a) and ( 4 a ) were s l i g h t l y l e s s a c t i v e . I t seems that t h e more t h e p o l y a n i o n i c c h a r a c t e r i s r e d u c e d by s u b ­ s t i t u t i o n , t h e more t h e m i t o g e n i c a c t i v i t y i s l o w e r e d . 3

3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

88

POLYMERS WITH CHAIN-RING STRUCTURES

A n t i g e n i c i t y o f a D I V E M A - H a p t e n - C o n j u g a t e ( 2 ) . The r e s u l t s of the H - t h y m i d i n e i n c o r p o r a t i o n experiments g i v e no i n f o r m a t i o n a b o u t t h e t y p e o f l y m p h o c y t e s sti­ m u l a t e d by DIVEMA. I t i s l i k e l y , t h o u g h n o t f o r m a l l y p r o v e n , t h a t t h e e n h a n c e d H - t h y m i d i n e u p t a k e i s due t o p r o l i f e r a t i o n of Β l y m p h o c y t e s . Whether the polymer f u r t h e r m o r e i s a n t i g e n i c a n d l e a d s t o an i n c r e a s e i n t h e numbyr o f a n t i b o d y f o r m i n g c e l l s c a n be t e s t e d u s i n g e i t h e r t h e p o l y m e r i t s e l f o r a p o l y m e r - h a p t e n con­ j u g a t e . In t h e l a t t e r c a s e a low m o l e c u l a r w e i g h t c o m ­ pound ( h a p t e n , w h i c h i s r e c o g n i z e d by t h e immune s y s t e m o n l y when b o u n d t o an i m m u n o g e n i c c a r r i e r ) i s l i n k e d t o t h e p o l y m e r . T h i s has t h e a d v a n t a g e t h a t a s t a n d a r d i z e d t e s t - s y s t e m common f o r a l l s u b s t a n c e s is available. Experimental r e s u l t i n d i c a t e t h a t t h e amoun the p o l y m e r - h a p t e n c o n j u g a t e i s c l o s e l y r e l a t e d to the a n t i g e n i c i t y o f t h e p o l y m e r i t s e l f ; t h e more a n t i g e n i c the p o l y m e r , the h i g h e r the a n t i b o d y p r o d u c t i o n a g a i n s t a hapten f i x e d to i t . P o l y m e r ( 2 ) was u s e d as a t e s t s u b s t a n c e . I t con­ t a i n s t h e d i n i t r o p h e n y l - m o i e t y , a c l a s s i c a l h a p t e n (DNP). P r o d u c t i o n o f D N P - s p e c i f i c a n t i b o d i e s was m e a s u r e d by a radio-immunoassay (antigen-binding test). F e m a l e CBA m i c e w e r e i m m u n i z e d w i t h d i f f e r e n t d o s e s o f ( 2 ) ( d a y 0) a n d r e i m m u n i z e d ( b o o s t e r e d ) w i t h t h e same d o s e ( d a y 2 1 ) . On day 3 1 , a b l o o d s a m p l e was t a k e n and t h e a n t i b o d i e s i n t h e s e r u m were p r e c i p i t a t e d by adding a I-labelled v i n y l polymer c o n t a i n i n g DNPmoieties (DNP-VINAM), 3

3

1 2 5

DNP-VINAM

a well

established

experimental

method

(_1_7). The

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

radio-

7.

GROS ET AL.

Behavior of DIVEMA

and DIVEMA

Derivatives

89

a c t i v i t y r e m a i n i n g i n t h e s u p e r n a t a n t was m e a s u r e d a n d t h e p e r c e n t b i n d i n g o f h a p t e n t o t h e a n t i b o d i e s was calculated. No s i g n i f i c a n t a n t i b o d y p r o d u c t i o n was f o u n d . R e i n v e s t i g a t i o n o f t h e number o f c e l l s p r o d u c i n g DNPs p e c i f i c a n t i b o d i e s with the plaque assay (which is much more s e n s i t i v e t h a n t h e a n t i g e n b i n d i n g t e s t ) conf i r m e d t h i s r e s u l t . T h e s e f i n d i n g s w o u l d n o t be t o o s u r p r i s i n g i f a weakly immunogenic c a r r i e r l i k e polyv i n y l p y r r o l i d o n e ) ( P V P ) was u s e d . In t h e c a s e o f DIVEMA, i t i s u n e x p e c t e d , s i n c e t h i s s u b s t a n c e - i n c o n t r a s t t o PVP - shows s t r o n g i n f l u e n c e s on t h e immune s y s t e m , e . g . m i t o g e n i c i t y f o r l y m p h o c y t e s . One p o s s i b l e e x p l a n a t i o n i s t h a t ( 2 ) i n d u c e s t o l e r a n c e a g a i n s t DNP. In o r d e r t o v e r i f m i c e were g i v e n a s t r o n g l j u g a t e c a l l e d DNP-KLH ( k e y h o l e l i m p e t h e m o c y a n i n e ) ( J 8 ) . One g r o u p o f a n i m a l s had b e e n p r e - t r e a t e d ("vaccinated") w i t h d i f f e r e n t d o s e s o f ( 2 ) , a c o n t r o l g r o u p had o n l y been g i v e n p h o s p h a t e b u f f e r i n j e c t i o n s on d a y s 1 0 , 6 a n d 1 b e f o r e i n j e c t i o n o f D N P - K L H . T a b l e i n shows t h e r e s u l t s of the a n t i g e n - b i n d i n g t e s t of blood samples from t h e two g r o u p s of m i c e a n d o f two c o n t r o l groups. T h e s e m e a s u r e m e n t s show t h a t s m a l l d o s e s o f DNPDIVEMA ( 2 ) g i v e n t o t h e m i c e b e f o r e t h e immune s y s t e m i s c h a l l e n g e d w i t h t h e p o t e n t a n t i g e n DNP-KLH, signific a n t l y suppress the f o r m a t i o n of D N P - s p e c i f i c antib o d i e s : (2) i n d u c e s t o l e r a n c e against DNP-KLH. T a k i n g i n t o a c c o u n t t h a t (2) i s m i t o g e n i c but s t i l l has no a n t i g e n i c e f f e c t , we s u g g e s t t h a t i n d u c t i o n o f t o l e r a n c e by t h i s p o l y m e r i s due t o f o r m a t i o n o f DNPs p e c i f i c s u p p r e s s o r c e l l s . T h i s w o u l d e x p l a i n why DIVEMA i s immune s t i m u l a t i n g ( i n d u c e s p r o l i f e r a t i o n o f lymphocytes) without causing production of a n t i b o d i e s : (2) i n d u c e s a c t i v e s u p p r e s s i o n and t h u s l e a d s t o t h e apparent lack of immunogenicity. E f f e c t s o f DIVEMA and DIVEMA P e r i v a t i y e s on Mouse Macrophages i n V i t r o . P o l y a n i o n s act n o t o n l y upon l y m p h o c y t e s , b u t a l s o on m a c r o p h a g e s ( 1 3 , ^_9). M a c r o p h a g e s a r e immune c e l l s w h i c h t a k e up f o r e i g n m a t e r i a l , h e l p l y m p h o c y t e s r e c o g n i z e and a t t a c k a n t i g e n s and p l a y an i m p o r t a n t r o l e i n t h e d e f e n s e o f t h e b o d y a g a i n s t tumour c e l l s (20). S c h u l t z e T ~ a l . ( 2 1 , 22) f o u n d t h a t m a c r o p h a g e s of D I V E M A - t r e a t e d mice i n h i b i t e d tumour c e l l proliferation i n v i t r o ; t h i s means t h a t DIVEMA a c t i v a t e s macrophages. The a u t h o r s d i d n o t f i n d c y t o t o x i c f a c t o r s i n t h e s u p e r n a t a n t of these macrophage c u l t u r e s . As p o l y a n i o n s c a n s t i m u l a t e many d i f f e r e n t m a c r o p h a g e f u n c t i o n s , we t r i e d t o f i n d o u t w h i c h f u n c t i o n s s

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

90

POLYMERS WITH CHAIN-RING STRUCTURES

Table

III

I n d u c t i o n o f t o l e r a n c e by DNP-DIVEMA ( 2 ) a g a i n s t DNPK L H . Mean v a l u e s o f 5 a n i m a l s . A n t i b o d y p r o d u c t i o n i s e x p r e s s e d as % h a p t e n ( j-DNP-VINAM) precipitated by t h e a n t i b o d i e s i n t h e s e r u m ( g r o u p s A a n d B) o r as t i t e r 3 3 % , t h a t i s t h e r e c i p r o c a l o f t h e serum d i l u t i o n a t w h i c h 33% o f I-DNP-VINAM a r e b o u n d a n d p r e c i p i ­ t a t e d ( g r o u p s C , D ) . T i t e r 33% was r e a c h e d i n g r o u p s C and D o n l y . 1 2 5

1

PBS CFA

2

5

= phosphate b u f f e r e d = complete Freund'

Group

saline

Treatment

Dose of (2),pg mouse

(background PBS days -10,-6,-1 control) CFA day 0 NaCl day 21

Β ( e f f e c t of DNP-DIVEMA itself)

C DNP-KLH alone

fc) days - 1 0 , - 6 , - 1 CFA day 0 NaCl day 21

-2.1

0,1 1 10 100

PBS days - 1 0 , - 6 , - 1 DNP-KLH (100 pg in CFA) day 0 DNP-KLH (10 pg i n NaCl) day 21

D (2)+DNPKLH

(2) days -10,-6,-1 DNP-KLH days 0 and 21

antibodies in serum day 31

8.6 7.7 6.4 2.2

+ 1.9

+ 11.1 + 6.0 Τ 5.0 + 4.6

12,340

0,1 1 10 100

2,380 6,880 7,220 12,400

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

7.

GROS E T A L .

Behavior of DIVEMA

and DIVEMA

Derivatives

91

a r e a c t i v a t e d . We c h o s e i n v i t r o t e s t s i n o r d e r t o a v o i d i n f l u e n c e o f m e t a b o l i s m . Two m a c r o p h a g e functions were t e s t e d : - s e c r e t i o n o f l y s o s o m a l enzymes and - r e l e a s e o f c y t o t o x i c f a c t o r s i n t o t h e s u p e r n a t a n t by D I V E M A - t r e a t e d macrophage c u l t u r e s . In o r d e r t o m e a s u r e s e c r e t i o n o f l y s o s o m a l enzymes, m a c r o p h a g e s o f n o r m a l , u n t r e a t e d NMRI m i c e were i n c u ­ b a t e d i n s e r u m - f r e e c u l t u r e medium (RPMI) a n d t r e a t e d w i t h d i f f e r e n t a m o u n t s o f compounds ( 1 c ) , ( 3 a ) , ( 4 a ) (mol.wt. 16,800),and ( 1 d ) , ( 3 b ) , (3c) (mol.wt. 24,000). S e c r e t i o n o f t h e f o l l o w i n g e n z y m e s was m e a s u r e d a f t e r 24 h o f i n c u b a t i o n u s i n g e s t a b l i s h e d b i o c h e m i c a l test systems : N-Acetyl-B-D-glucosaminidas d a s e ( β - G l u ) J2j4)and l a c t a t l a t t e r enzyme i s l o c a t e d i n t h e c y t o p l a s m a n d i s n o t a c t i v e l y s e c r e t e d ( a s t h e o t h e r two e n z y m e s a r e ) b u t o n l y s e t f r e e i f t h e c e l l membrane i s d e s t r o y e d : t h e LDH l i b e r a t e d i n f o r m s a b o u t v i a b i l i t y o f c e l l cultures o r c y t o t o x i c e f f e c t s on m a c r o p h a g e s o f t h e s u b s t a n c e tested. None o f t h e s u b s t a n c e s c a u s e d s i g n i f i c a n t enzyme s e c r e t i o n by m a c r o p h a g e s . O n l y t h e p y r r o l i d o n e d e r i ­ v a t i v e ( 3 a ) c a u s e d a s l i g h t i n c r e a s e o f LDH w i t h i n ­ c r e a s i n g dose o f t h e p o l y m e r . T h i s f i n d i n g corresponds t o t h e h i g h e r a c u t e t o x i c i t y o f ( 3 b ) as c o m p a r e d t o u n s u b s t i t u t e d DIVEMA d e r i v a t i v e ( 1 b ) . These r e s u l t s a r e u n e x p e c t e d , s i n c e d e x t r a n s u l ­ f a t e w i t h s i m i l a r m o l . w t . does i n d u c e s e c r e t i o n o f enzymes ( 2 6 ) . Release of c y t o t o x i c f a c t o r s i n t o the supernatant was t e s t e d by a d d i n g t h e s u p e r n a t a n t o f D I V E M A - t r e a t e d m a c r o p h a g e s t o c u l t u r e s o f d e f i n e d a m o u n t s o f P815 t u m o u r c e l l s a n d m e a s u r i n g LDH f r o m l y s e d t u m o u r c e l l s a f t e r 24 hr. o f i n c u b a t i o n . F i g u r e 1 shows s c h e m a t i c a l l y how t h e e x p e r i m e n t was done. A l l substances t e s t e d , ( 1 c ) , ( 1 d ) , ( 3 a ) , ( 3 b ) , ( 4 a ) , (4b), c a u s e d i n c r e a s i n g c y t o t o x i c a c t i v i t y o f t h e s u p e r ­ n a t a n t w i t h i n c r e a s i n g doses o f t h e p o l y m e r s . Though the a b s o l u t e values of L D H - 1 i b e r a t i o n d i f f e r g r e a t l y f r o m one e x p e r i m e n t t o a n o t h e r , t h i s q u a l i t a t i v e result i s t h e same i n a l l t e s t s ( J J _ ) . One t y p i c a l diagram showing t h e dose dependency o f s u p e r n a t a n t m e d i a t e d t o x i c i t y c a u s e d by p o l y m e r ( 3 b ) i s shown i n F i g . 2. R e l a t i v e l y l o w c o n c e n t r a t i o n s (50 - 100 p g / m l ) were s u f f i c i e n t to cause s u b s t a n t i a l c y t o t o x i c i t y . As f a r as we know, t h i s i s t h e f i r s t e x a m p l e o f s u p e r n a t a n t - m e ­ d i a t e d t o x i c i t y c a u s e d by DIVEMA. I t i s c o n t r a d i c t o r y t o t h e r e s u l t s o f S c h u l t z e t al.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

92

POLYMERS WITH CHAIN-RING STRUCTURES

tumor

cells

tumor

cells

supermatant

DETERGENT

macrophages

eel I-lysis measured by enzyme release

ι

• DIVEMA

ι

lysi detergent-effect

Figure I.

1007· lysis

Test system for measuring cytotoxicity in the supernatant of macrophage cultures.

t

Figure 2.

Supernatant-mediated cytotoxicity caused by DIVEMA derivative (3b in Table II) (three independent runs).

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

7.

GROS E T A L .

Behavior of DIVEMA

and DIVEMA

Derivatives

93

( 2 1 , 2j2) ; t h i s may be due t o t h e f a c t t h a t t h e s e a u T h o r s used s e r u m - c o n t a i n i n g c u l t u r e m e d i a . Our r e s u l t s d e m o n s t r a t e t h a t e v e n c h e m i c a l l y m o d i f i e d DIVEMA c a u s e s - a t l e a s t i n v i t r o - t h e same b i o l o g i c a l e f f e c t ( r e l e a s e o f c y t o t o x i c f a c t o r s ) as DIVEMA i t s e l f . T h i s a s p e c t i s e s p e c i a l l y i m p o r t a n t i f one u s e s DIVEMA as a c a r r i e r polymer f o r antitumour agents hoping to r e t a i n immune s t i m u l a t i n g p r o p e r t i e s . Endocytic

Behaviour

o f DIVEMA a n d

Derivatives

M a c r o p h a g e s h a v e one more i m p o r t a n t p r o p e r t y : t h e y i n g e s t f o r e i g n m a t e r i a l v i a e n d o c y t o s i s , a p r o c e s s which r e s e m b l e s t h e i n g e s t i o n o f m a t e r i a l by a m o e b a e . P o l y m e r s may e i t h e stimulate endocytosi t h e l a t t e r p o s s i b i l i t y w i t h two e s t a b l i s h e d t e s t systems ( 2 7 ) , ( 2 8 ) : -

Uptake

of

I - l a b e l led poly(vinylpyrrolidone) by r a t m a c r o p h a g e s . ( T h i s p o l y m e r i s up by p i n o c y t o s i s i n t h e f l u i d p h a s e ) . 1 2 5

(125j'-pvp) taken -

Uptake o f A u ( c o l l o i d a l ) by mouse m a c r o p h a g e s . ( T h i s c o l l o i d i s m a i n l y t a k e n up a f t e r a d s o r p t i o n a t the c e l l membrane). P o l y m e r s ( 1 a ) , ( 1 b ) , ( 1 d ) , ( 3 a ) , ( 4 a ) a n d ( 5 ) were t e s t e d . F i g u r e 3 shows t h e E n d o c y t i c I n d e x ( 2 8 ) m e a s u r e d The DIVEMA d e r i v a t i v e s ( 1 a ) , ( 3 a ) a n d ( 4 a ) ïïâve no s i g n i f i c a n t e f f e c t on t h e p i n o c y t o s i s o f J-PVP (they do n o t i n f l u e n c e t h e r a t e o f f o r m a t i o n o f p i n o c y t i c v e s i c l e s ) . P o l y m e r ( 1 d ) shows m a r k e d i n h i b i t i o n o f p i n o c y t o s i s at the highest dose.(This l a t t e r f i n d i n g in v i t r o corresponds to in vivo r e s u l t s of Breslow et au (29)). They f o u n d t h a t t h e removal o f c o l l o i d a l c a r b o n f r o m t h e b l o o d o f t e s t a n i m a l s i s i n h i b i t e d by h i g h m o l e c u l a r weight DIVEMA). Polymer (5) causes a d e c r e a s e o f p i n o c y t o s i s w i t h i n c r e a s i n g dose. The f a i l u r e o f d e r i v a t i v e s ( 3 a ) a n d ( 4 a ) t o i n f l u e n c e p i n o c y t o s i s may be due t o t h e i r r e d u c e d p o l y a n i o n - c h a r a c t e r . The i n h i b i t o r y e f f e c t o f t h e h y d r o p h o b i c d e r i v a t i v e ( 5 ) may be a t t r i b u t e d t o i n t e r a c t i o n s o f a l k y l c h a i n s w i t h t h e l i p i d membrane* These r e s u l t s o b t a i n e d with the I-PVP-test s y s t e m , as w e l l as e x p e r i m e n t s u s i n g t h e c o l l o i d a l g o l d t e s t s y s t e m , a r e d i s c u s s e d i n more d e t a i l i n r e f . (27). T h i s work i s p a r t o f t h e P h . D . t h e s i s o f R . S c h n e e (11). 1 9 8

1 2 5

1 2 5

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

94

POLYMERS

WITH

CHAIN-RING

STRUCTURES

(5)

0,1 + φ ο

(Ια)

(lb)

(1c)

(3a)

(4a)

χ φ C

M

Ο

iftl

Ul

o°R8

°g

concentrations

o^gg

oosg

ooog

ooog

in( pg/ml)

Figure 3. Stimulation of endocytosis by DIVEMA and DIVEMA derivatives. Endocytic index in the macrophage test system and I-PVP used as standard sub­ stance. 125

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

7.

GROS E T A L .

Behavior of DIVEMA

and DIVEMA

Derivatives

95

Acknowledgements We are indebted to Prof. Dr.D. Breslow for the DIVEMA samples. This work was supported in part by the B r i t i s h Science Research Council and the Deutsche Forschungsgemeinschaft. R.S. thanks the Fonds der Chemie for a Ph.D. fellowship. Literature Cited 1. Kostelnik, R.J. (Ed.), "Polymeric Delivery Systems", Midland Macromolecular Monographs V o l . 5, Gordon & Breach, N.Y. 1975 2. Donaruma, G.L., Vogl Academic Press, N.Y 3. Gros, L., Ringsdorf, H., Schupp, H., Angew.Chem.Int Ed., 1981, 93, 305 - 325 4. Donaruma, L.G., Ottenbrite, R.M., Vogl, O. (Eds.), "Anionic Polymeric Drugs", John Wiley & Sons, N.Y. 1980 5. B u t l e r , G.B., see 4., p. 49 - 142 6. Breslow, D.S., Pure Appl.Chem. 1976, 46, 103 7. Regelson, W., Morahan, P., Kaplan, A. in "Polye l e c t r o l y t e s and Their Applications" (A. Rembaum, E. Sélégny, Eds.) D. Reidel Publ. Comp., Dordrecht+ Boston 1975, p. 131 - 144 8. P r z y b y l s k i , M., Zaharko, D.S., Chirigos, M.A., Adamson, R.H., Schultz, R.M., Ringsdorf, H. Cancer Treat.Rep. 1978, 62, 1837 9. Hirano, T . , Klesse, W., Ringsdorf, H., Makromol. Chem. 1979, 180, 1123 10. Hirano, R. Ringsdorf, H., Zaharko, D.S., Cancer Res. 1980, 40, 2263 11. Schnee, R., Ph.D. T h e s i s , Mainz 1980 12. Kobayashi, S., Ringsdorf, H., in preparation (unpubl. results) 13. Butler, G.B., see 4 . , p. 185 - 210 14. Snippe, H., Nab, J . , van Eyk, R.V.W., Immunology 1974, 27, 761 15. Golan, D.R., B o r e l , Y., J.Exp.Med. 1971, 134, 1046 16. Schmidtke, J . R . , Dixon, R . J . , J.Exp.Med. 1972, 136 392 17. Wrede, J., Rüde, E., Thumb, R., Meyer-Debus, M. Eur.J.Immunol. 1973, 3,798 18. M i s h e l l , B.B., S h i i g i , S.M.,"Selected Methods in C e l l u l a r Immunology", W.H. Freeman & Co. San Francisco 1980 19. see 4., p. 234 - 236 and p. 196 - 198

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

96

POLYMERS WITH CHAIN-RING STRUCTURES

20. James, K., McBride, B. and Stuart, H. (Eds.) "The Macrophage and Cancer" Proceedings of the European Reticuloendothelial Society, Symposium Edinburgh Sept. 12 - 14 , 1977, Edinburgh 1977 21. Schultz, R.M., Papamatheakis, J.Β., Luetzler, J . , Chirigos, M.A., Cancer Res. 1977, 37, 3338 22. Schultz, R.M., Papamatheakis, J.P., Chirigos, M.A., Cell Immunol. 1977, 29, 403 23. Woolen, J.P., Heyworth, R., Walker, P.G., Biochem.J. 1961, 78, 111 24. Talalay, P., Fishman, W.H., Huggins, C., J . B i o l . Chem. 1946, 166, 757 25. Bergmeyer, H.U. (Ed.) "Methoden der enzymatischen Analyse" Verlag Chemie, Weinheim FRG, 1970, p. 533 26. Schorlemmer, H.U. A l l i s o n , A.C., C l i n 88 27. Pratten, M.K., Duncan, R., Cable, H.C., Schnee, R., Ringsdorf, H., Lloyd, J.B., Chemico-Biological Interactions, 1981, 35, 319 28. Pratten, M.K., Lloyd, J.B., Biochem.J. 1979, 180, 567 29. Breslow, D.S., Edwards, E.F., Newburg, N.R., Nature 1973, 246, 160 th

RECEIVED February 1, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

8 Radical Polymerization of exo and endo N-Phenyl-5-norbornene-2,3-dicarboximides as Models for Addition-Curing Norbornene End-Capped Polyimides 1

NORMAN G. G A Y L O R D and MICHAEL M A R T A N Gaylord Research Institute Inc., New Providence, NJ 07974

Homopolymerization of exo and endo cyclopentadieneN-phenylmaleimide 150-260°C and i in the presence of radical catalysts having half­ -lives of less than 2 hr at reaction temperature. The low molecular weight (< 2000), saturated (H-NMR in CDCl ) homopolymer retained the configuration of the adduct when the polymerization temperature was below 200°C but contained both endo and exo configurations, due to isomerization, when prepared from either isomer at 260°C. The proposed saturated structure with N-phenylnorbornane-2,3-dicarboximide repeating units with 5,7-linkage, is presumably present in the cross­ -linked products from the high temperature curing of norbornene end-capped addition-type polyimides. 1

3

Aromatic polyimides have achieved considerable success as high temperature-resistant polymers. Since the desired high molecular weight polyimides are not readily processable, they are generated in situ by the thermal ring closure of the processable precursor poly(amic-acids) (2). The use of low molecular weight prepolymers, i.e. poly ( amic-ac ids ), as laminating resins is limited by their conversion to an intractable state before complete elimination of volatile by-products. This problem has been alleviated by the use of low molecular weight polyimide prepolymers end-capped with norbornene rings (3, 4, 5)

1

See Reference 1. 0097-6156/ 82/0195-0097$06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

98

POLYMERS WITH CHAIN-RING

STRUCTURES

or monomeric r e a c t a n t s polymerizable t h e r e t o ( 5-É3)

H OCH

2

N ^ ) . C H

2

^

N H

2

+

n

A t e l e v a t e d temperatures the terminal norbornene r i n g s presumably undergo a d d i t i o n p o l y m e r i z a t i o n t o promote c r o s s l i n k i n g w i t h m i n i mal formation of v o l a t i l e by-products. The mechanism of the c r o s s l i n k i n g r e a c t i o n has been p o s t u l a t e d as (a) d i s s o c i a t i o n of the t e r m i n a l cyclopentadiene-N-arylmaleimide D i e l s - A l d e r adduct t o the monomeric p r e c u r s o r s , which immediately r e a c t t o form i z a t i o n of the u n d i s s o c i a t e s a t u r a t e d polymer {5),

é

Ο

and as (b) homopolymerization of the norbornene r i n g i n the termi­ n a l D i e l s - A l d e r adduct through an u n s p e c i f i e d mechanism, although presumably i n v o l v i n g r i n g opening and/or d i s s o c i a t i o n , t o form an unsaturated a l t e r n a t i n g copolymer (8, 9).

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

8.

GAYLORD AND MARTAN

W-Vhenyl-5-mrbornene-2 3-d\carboximides

99

t

The r a d i c a l c a t a l y z e d homopolymerization o f the furan-maleic anhydride (F-MAH) D i e l s - A l d e r adduct y i e l d s a s a t u r a t e d homopolymer a t temperatures below 60 C, and an unsaturated equimolar a l t e r n a t i n g copolymer a t e l e v a t e d temperatures, due t o r e t r o g r a d e d i s s o c i a t i o n o f the adduct (10, 11). The c o p o l y m e r i z a t i o n o f monomeric f u r a n and maleic anhydride y i e l d s the same unsaturated a l t e r n a t i n g copolymer, independent o f temperature (10).

In c o n t r a s t , the r a d i c a l c a t a l y z e d homopolymerization of the cyclopentadiene-maleic anhydride (CPD-MAH) D i e l s - A l d e r a d d u c t y i e l d s a s a t u r a t e d homopolymer a t temperatures as h i g h as 220 C, while r e t r o g r a d e d i s s o c i a t i o n occurs a t even h i g h e r temperatures. Nevertheless, the c o p o l y m e r i z a t i o n o f monomeric c y c l o p e n t a d i e n e and maleic anhydride y i e l d s a s a t u r a t e d 1:2 copolymer (12-15). Q

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

100

POLYMERS WITH CHAIN-RING STRUCTURES

Since the F-MAH and CPD-MAH D i e l s - A l d e r adducts y i e l d unsatur a t e d and s a t u r a t e d polymers, r e s p e c t i v e l y , as a r e s u l t o f r a d i c a l c a t a l y z e d homopolymerization a t e l e v a t e d temperatures, i t was o f i n t e r e s t t o i n v e s t i g a t e the r a d i c a l c a t a l y z e d p o l y m e r i z a t i o n o f the isomeric exo- and endo-cyclopentadiene-N-phenylmaleimide adducts, models f o r the norbornene end-capped p o l y i m i d e s whose thermal p o l y m e r i z a t i o n products have s t r u c t u r e s which have been d i v e r s e l y d e p i c t e d as s a t u r a t e d and unsaturated, without e x p e r i mental v e r i f i c a t i o n . Experimental The r e c r y s t a l l i z e d CPD-MAH D i e l s - A l d e r adduct, endo-cis-norbornene-2,3-dicarboxylic anhydride, mp 165 C, was maintained a t 220 C f o r 4 hr t o y i e l d 101 C. The crude produc t o i s o l a t e the exo isomer, mp 141 C. The endo- and exo-cis-Nphenyl-5-norbornene-2,3-dicarboximides, mp 144 and 197 C, r e s p e c t i v e l y , were prepared by r e a c t i o n o f the endo- and exo-CPD-MAH adducts w i t h a n i l i n e . The p o l y m e r i z a t i o n o f the adducts was c a r r i e d out by adding 0.2ml o f e i t h e r t - b u t y l p e r a c e t a t e (tBPA), t - b u t y l perbenzoate (tBPB) o r t - b u t y l hydroperoxide (tBHP-70 c o n t a i n i n g 70% tBHP and about 30% d i - t - b u t y l peroxide o r tBHP-90 c o n t a i n i n g 90% tBHP and about 10% t - b u t y l a l c o h o l ) , by s y r i n g e i n f o u r equal p o r t i o n s over a 20 min p e r i o d t o 2g o f the adduct i n a rubber-capped tube immersed i n a c o n s t a n t temperature bath. The mixture was then m a i n t a i n ed a t temperature f o r an a d d i t i o n a l 40 min. Reactions a t 120 C were conducted i n 3ml chlorobenzene. The r e a c t i o n product was d i s s o l v e d i n acetone and p r e c i p i t a t e d w i t h methanol t w i c e . IR s p e c t r a were recorded from f i l m s c a s t on NaCl p l a t e s from acetone s o l u t i o n u s i n g a P e r k i n Elmer Model 21 spectrophotometer. NMR s p e c t r a were o b t a i n e d a t 60MHz i n CDCl^ a t 25 C u s i n g t e t r a m e t h y l s i l a n e as i n t e r n a l standard. q

R e s u l t s and D i s c u s s i o n A f t e r 5 h r a t 170°C, endo-N-phenyl-5-norbornene-2,3-dicarboximide f a i l e d t o undergo i s o m e r i z a t i o n and remained unchanged. S i m i l a r l y , no i s o m e r i z a t i o n o f the exo adduct was d e t e c t i b l e by IR a n a l y s i s a f t e r 5 h r a t 170°C. However, a f t e r 30 min a t 260°C, the exo o r endo adduct was converted t o a 40/60 endo/exo e q u i l i b r i u m mixture, which remained unchanged a f t e r 2 h r a t 260 C. The homopolymerization o f the endo and exo adducts was c a r r i e d out i n the melt a t 150° t o 260°C and i n chlorobenzene a t 120 C (Table I ) . Polymer was obtained when the c a t a l y s t was used a t a temperature where the h a l f - l i f e was s h o r t , e.g. l e s s than 2 h r , c o n d i t i o n s shown t o be e f f e c t i v e i n the homopolymerization o f male i c anhydride (16), norbornene (17, 18) and 5-norbornene-2,3-dic a r b o x y l i c anhydride (CPD-MAH adduct) (12-15), as w e l l as the

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

8.

N-PhenyU5-norbornene-2,3-dicarboximides

GAYLORD AND MARTAN

101

c o p o l y m e r i z a t i o n o f a c y c l i c dienes (19, 20) and c y c l o p e n t a d i e n e (12-15) w i t h maleic anhydride. TABLE I HOMOPOLYMERIZATION OF CYCLOPENTADIENE-N-PHENYLMALEIMIDE DIELS-ALDER ADDUCTS Catalyst

^\/2

y

m

i

n

Solvent

Temp, °C

Yield, %

endo adduct tBPA tBHP-70 tBPB tBHP-70 tBHP-70

66 720 4 0.8 0.01

CB none non non none

120 150

60 0

260

50

120 155 260

46 60 30

exo adduct tBPA tBPA tBHP-90

66 2 1

CB CB none

Elemental and NMR a n a l y s e s i n d i c a t e d t h a t the homopolymers c o n t a i n e d equimolar amounts o f c y c l o p e n t a d i e n e and N-phenylmaleimide, i r r e s p e c t i v e o f p o l y m e r i z a t i o n temperature w i t h i n the 120260 C range. The homopolymers from the exo and endo adducts had s o f t e n i n g p o i n t s o f 240 and 265-280°C, r e s p e c t i v e l y . The polymer from the p o l y m e r i z a t i o n o f the endo adduct a t 120 C had a molecul a r weight o f 1645 (vapor pressure osmometry). The NMR s p e c t r a o f the homopolymers o b t a i n e d from the endo and exo adducts a t temperatures below 200 C i n d i c a t e d t h a t the polymers r e t a i n e d the c o n f i g u r a t i o n o f the monomeric adducts. The spectrum o f the endo adduct homopolymer c o n t a i n e d a peak c e n t e r e d at , not present i n the spectrum o f the exo adduct homopolymer. The endo adduct homopolymer spectrum c o n t a i n e d broad peaks a t 7.0-7.7 and 7.8-8.6^, while the exo adduct homopolymer s p e c t rum had a narrow peak a t 7 . 0 - 7 . 4 f , c e n t e r e d a t 7.25^, and a broader peak a t 8 . 3 - 8 . 9 B o t h s p e c t r a had the peaks o f aromatic hydrogens a t 2.4-3.0 N e i t h e r spectrum c o n t a i n e d peaks a t about 4.0^ a t t r i b u t a b l e t o v i n y l i c hydrogens, i n d i c a t i n g the absence of u n s a t u r a t i o n (Figure 1 ) . The NMR s p e c t r a o f the homopolymers o b t a i n e d from the endo and exo adducts a t 260 C were s i m i l a r t o each o t h e r and d i f f e r e n t from those o b t a i n e d from the homopolymers o f e i t h e r adduct polymeri z e d a t lower temperatures. The s p e c t r a c o n t a i n e d peaks a r i s i n g from both endo and exo isomers, i n d i c a t i n g t h a t the adducts had undergone some endo-exo i s o m e r i z a t i o n . No u n s a t u r a t i o n was shown i n the spectrum o f e i t h e r homopolymer o b t a i n e d a t 260 C (Figure 2 ) .

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

102

POLYMERS WITH CHAIN-RING

STRUCTURES

Figure 2. NMR spectra of homopolymer from peroxide catalyzed polymerization of the exo adduct at 260°C (a), and the endo adduct at 260°C (b).

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

8.

GAYLORD AND MARTAN

N-Phenyl-5-norbomene-2,3-dicarboximides

103

The s a t u r a t e d s t r u c t u r e s o f the homopolymers obtained both a t temperatures below 200°C w i t h r e t e n t i o n o f the endo o r exo conf i g u r a t i o n o f the monomeric adduct, and a t 260 C w i t h both endo and exo c o n f i g u r a t i o n s , suggests a simple double bond a d d i t i o n .

I t has p r e v i o u s l y bee from the homopolymerizatio D i e l s - A l d e r adduct (12-15), and probably from the furan-maleic anhydride D i e l s - A l d e r adduct (11), have rearranged s t r u c t u r e s . An analogous s t r u c t u r e would a r i s e from the homopolymerization o f the cyclopentadiene-N-phenylmaleimide CPD-NPMI adduct, as f o l l o w s :

The r e t r o g r a d e d i s s o c i a t i o n o f the D i e l s - A l d e r adduct t o gene r a t e the diene and d i e n o p h i l e , f o l l o w e d by the p o l y m e r i z a t i o n o f the comonomer charge t r a n s f e r complex, has p r e v i o u s l y been p r o posed (12-15) i n the p o l y m e r i z a t i o n o f the CPD-MAH adduct, i n the presence o f peroxides having s h o r t h a l f - l i v e s a t the e l e v a t e d p o l y m e r i z a t i o n temperatures. Under these c o n d i t i o n s , the ground s t a t e complex, presumably i n v o l v e d i n endo-exo i s o m e r i z a t i o n , i s converted t o the e x c i t e d s t a t e complex which undergoes the i n d i cated polymerization. The c r o s s l i n k e d products r e s u l t i n g from the h i g h temperature " p y r o l y t i c p o l y m e r i z a t i o n " (_5) c u r i n g o f the norbornene end-capped

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

104

POLYMERS WITH CHAIN-RING

STRUCTURES

"addition-type" polyimide prepolymers, such as P13N, P10P, etc., as well as those prepared by means of in situ polymerization of monomeric reactants (PMR), at least those obtained at temperatures up to 260 C, may be presumed to have saturated structures similar to those obtained from the polymerization of the isomeric N-phenyl5-norbornene-2,3-dicarboximides at elevated temperatures. The weight loss or volatilization noted during curing has been attrib­ uted to the escape of volatile by-products, e.g. cyclopentadiene, which are formed by dissociation of the norbornene end-caps (_3, £3). This is consistent with our proposed polymerization mechanism and polymer structure. Subsequent to the presentation of the results reported here­ in (21),^C and 270 MHz H-NMR studies of the thermally induced polymerization of the N-phenyl-5-norbornene-2,3-dicarboximides (22) and C-NMR studie polymers (23) were reported adducts takes place at 200 C and above. Retrograde dissociation of the CPD-NPMI adduct occurs above 275 C and the saturated poly­ mers obtained at temperatures of 285 C and above contain units derived from the exo and endo CPD-NPMI adducts as well as units derived from N-phenylmaleimide and the Diels-Alder adducts of liberated cyclopentadiene and the CPD-NPMI adducts. The proposed saturated structures suggest simple addition across the norbor­ nene (CPD-NPMI and CPD-CPD-NPMI) and maleimide (NPMI) double bonds, in the absence of concrete evidence to support the rearranged structures postulated herein and in the products of earlier cat­ alytic polymerizations. The proposed copolymerization of the norbornene and maleimide double bonds is in agreement with our finding that the peroxyester-catalyzed copolymerization of mono­ meric cyclopentadiene and N-phenylmaleimide at 85 C and 155 C yields saturated copolymers containing the NPMI and CPD in 2/1 mole ratio (24). o

1

Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10.

Donor-Acceptor Complexes in Copolymerization. LXI. Sroog, C. E. Macromol. Revs. 1976, 11, 161. Lubowitz, H. R. (to TRW Inc.) 1970, U. S. Patent 3,528,950. Lubowitz, H. R. Polymer Preprints 1971, 12, 329. Serafini, T. T.; Delvigs, P.; Lightsey, G. R. Applied Polymer Symposium 1973, 22, 89; and other references cited therein. Serafini, T. T.; Delvigs, P.; Lightsey, G. R. J . Appl. Polym. Sci. 1972, 16, 905. Serafini, T. T. in May, C. Α., Ed. "Resins for Aerospace"; ACS Symposium Series 1980, 132, 15. Dynes, P. J.; Panos, R. M.; Hamermesh, C. L. J . Appl. Polym. Sci. 1980, 25, 1059. Dokoshi, N. Kobunshi 1974, 23, 125. Gaylord, N. G.; Maiti, S.; Patnaik, Β. K.; Takahashi, A. J. Macromol. Sci.-Chem. 1972, A6, 1459.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

8.

GAYLORD AND MARTAN

'S-Pheny U5-norbornene^ ,3-dicarboximides

105

11. Gaylord, N. G.; Martan, M.; Deshpande, A. B. J . Polym. Sci., Polym. Chem. Ed. 1978, 16, 1527. 12. Gaylord, N. G.; Solomon, O.; Stolka, M.; Patnaik, Β. K. J. Polym. Sci., Polym. Lett. Ed. 1974, 12, 261. 13. Gaylord, N. G.; Solomon, O.; Stolka, M.; Patnaik, Β. K. J. Macromol. Sci.-Chem. 1974, A8, 981. 14. Gaylord, N. G. Polymer Preprints 1976, 17, 666. 15. Gaylord, N. G.; Deshpande, A. B.; Martan, M. J . Polym. Sci., Polym. Lett. Ed. 1976, 14, 679. 16. Gaylord, N. G.; Maiti, S. J . Polym. Sci., Polym. Lett. Ed. 1973, 11, 253. 17. Gaylord, N. G.; Mandal, Β. M.; Martan, M. J . Polym. Sci., Polym. Lett. Ed. 1976, 14, 555. 18. Gaylord, N. G.; Deshpande, A. B.; Mandal, Β. M.; Martan, M. J. Macromol. Sci.-Chem 19. Gaylord, N. G.; Stolka J. Macromol. Sci.-Chem. 1971, A5, 867. 20. Gaylord, N. G.; Stolka, M.; Patnaik, B. K. J . Macromol. Sci.Chem. 1972, A6, 1435. 21. Gaylord, N. G.; Martan, M. Polymer Preprints 1981, 22, 11. 22. Wong, A. C.; Ritchey, W. M. Macromolecules 1981, 14, 825. 23. Wong, A. C.; Garroway, A. N.; Ritchey, W. M. Macromolecules 1981, 14, 832. 24. Gaylord, N. G.; Martan, M.; Deshpande, A. B. Polym. Bulletin 1981, 5, 623. RECEIVED

February 25, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

9 Cyclization Reaction of N-Substituted Dimethacrylamides in the Crystalline and Glassy States at 77 Κ T. KODAIRA, M . TANIGUCHI, and M . SAKAI Fukui Universiy, Department of Industrial Chemistry, Faculty of Engineering, Fukui 910, Japan

N-Methyldimethacrylamide (MDMA) cyclizes to give a

5-membered cyclic has been deduced base MDMA irradiated at 77 K. ESR studies of MDMA deuterated at its four methylene protons of the methacryl groups supported above conclusion. Crystal data of MDMA tell us that the formation of 5-mem­ bered ring is the most favorable reaction in the crystalline state. It was found that N-benzyl and N-propyl substituents can also form 5-membered ring at 77Kin both their crystalline and glassy states. Molecular structures of these monomers in these states are not available, but these results suggest that ΒDMA and PDMA have favorable conformations for the formation of 5-membered ring. Cyclopolymerization of Ν-substituted dimethacrylamide(RDMA) has been reported by several research groups(1^7). The repeating units which are expected in the polymers prepared from RDMA are 5-membered ring, 6-membered ring, and uncyclic pendant groups. Structural investigations have shown that their main repeating unit is 5-membered ring. They contain small amounts of 6-membered ring but do not contain any detectable pendant double bond04,5) · Propyl(PDMA) and benzyl(BDMA) substituante form glassy and super­ cooled liquid states when they are quenched rapidly from above their melting points. The polymerization at the supercooled l i q ­ uid state yields polymers with essentially the same structure as those obtained in the liquid state (7)· The contents of 5-membered ring are almost the same for both polymers formed in the liquid and supercooled liquid states while the fraction of 5-membered ring decreases on their polymerization in the solid state. How­ ever, the polymers formed in the solid state were found to be amorphous and the mechanism of the polymerization could be ex­ plained fundamentally based upon that of liquid state(7). The de­ tailed investigation on the cyclopolymerization of BDMA has led to 0097-6156/82/0195-0107$06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

108

POLYMERS WITH CHAIN-RING STRUCTURES

the conclusion that the high tendency of RDMA to cyclization was due to the non-polymerizability of i t s monofunctional counterpart (5). N-Alkyl-N-i8obutyrylmethacrylamide(I) just corresponds to the mono functional counterpart of RDMA and i t would not polymerize to give a high polymer (4,5) . I t has been proposed that the lower the polymerizability of the monofunctional counterparts of b i functional monomers, the higher their cyclopolymerizability(5) and the v a l i d i t y of the hypothesis has been proven i n several monomers (8-11). Some of the reported results on the cyclopolymerization of bifunctional monomers are considered to be the additional e v i ­ dences which support above hypothesis, judging from their high tendency to cyclization and low polymerizability of their monofunctional counterparts(12,13,14). During these studies i t was found that the rate-determining step of the cyclopolymerizatio cooled liquid states i s (5,7,15). This conclusion has been deduced because only an un CH. 3

CH.

I

CH -C

2

1

CH.

0

I I CH.-C

0

2

CH

C-CH

1 ι

N-R

I R

H. Ξ

I

I >

2

ι

I

0

RDMA

CH.

CH -C»

OCH

0

3

1

ι

/

0

2

R

II

I

oo j

H-C-CH

Κ

3

3

Ϊ

1

I

3

2

ι R

2

3

Τ

1

I

III

R

CH„

I CH « C 2

1 X

3

IV

CH„ H. Ξ

I »

'3

CH.-O 3

1 X

cyclic propagating radical (IV) was observed on the measurements of ESR spectra of irradiated RDMA at polymerization temperature. Radiation polymerization of unsaturated monomers i n the solid state proceeds through the i n i t i a t i o n radical(V) which i s formed by the additiom of hydrogen atom to their double bond(16). Based upon these facts the formation of an i n i t i a t i o n radical(II) i n RDMA by the reaction between a hydrogen atom and one of the double bonds of RDMA i s reasonably assumed. This i n i t i a t i o n radical cy-

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

9. KODAIRA E T AL.

109

^-Substituted Dimethacrylamides

clizee to give the 5-membered cyclic radical(III) which reacts with other monomer to y i e l d the uncyclic propagating radical(IV). At higher temperature where polymerization proceeds, only the uncyclic propagating radical was detected as mentioned previously. Decrease in temperature reduces molecular motion and the polymerization does not proceed. These considerations suggest that we might be able to observe the i n i t i a t i o n radical(II) and the 5-membered c y c l i c radical(III) at lower temperature. The i n i t i a t i o n radical(II) affords a seven line spectrum i f two methyl groups are rotating freely, and the 5-membered c y c l i c radical gives a 3-line spectrum i f the ro­ tation abount the C-C bond of >C-CH2* group i s free. A 12-line spectrum has already been assigned to the uncyclic propagating radical(15). Therefore, we can easily distinguish these three rad­ i c a l s and accordingly, the two reaction steps, i . e . , an intramo­ lecular cyclization and intermolecula radical III and a RDMA molecule irradiated RDMA. These reactions should be strongly influenced by the phases where they are carried out. The effect of the phases on these re­ actions can be studied by using RDMA because PDMA and BDMA can form glassy, supercooled l i q u i d and crystalline states. The pur­ pose of the present investigation i s to identify the i n i t i a t i o n ( I I ) and cyclic (III) r ai cals, and to see the effect of the phases on these intramolecular cyclization and intermolecular propagation reactions. Crystalline structure of MDMA has recently been determined(17). Therefore, these reaction procedures can be studied i n connection with the crystalline structure i n the case of MDMA. Experimental RDMA was prepared according to the procedure described pre­ vious ly (6^,18). MDMA and PDMA deuterated at their CH -C< protons (MDMA-d^ and PDMA-d^, respectively) were synthesized starting from deuterated methacrylic acid which was obtained by the hydrolysis of deuterated ethylmethacrylate prepared based upon the reported procedure using CD90(19). The degree of deuteration was 100% ac­ cording to NMR measurements. Single crystals of MIMA and MDMA-d^ were grown by slow evaporation of benzene solution at room temper­ ature. The crystals obtained from both the monomers had form shown i n Figure 1. The coordinate axis system employed for the ESR measurements i s also given i n Figure 1. Samples for ESR spectra were prepared i n Suprasil tubes. The shape of the bottom of the sample tubes was modified to accomodate the single crystal according to Kurlta(20). However an error of about 10° i n determining the orientation of crystal was i n e v i ­ table because of the d i f f i c u l t y i n settling the crystal. ESR mea­ surements were made with JEOL JES-FE-1X or Varian E-3 EPR X-band spectrometer. γ-Ray irradiation was carried out by using 60Co source. 2

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

110

POLYMERS WITH CHAIN-RING

Figure 1.

The crystal form of MDMA and MDMA-à ESR measurements.

k

STRUCTURES

and the axes employed for

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

9.

KODAIRA ET AL.

111

^-Substituted Dimethacrylamides

Results and Discussion ESR Studies of MDMA and MDMA-dA. An isolated radical and rad­ i c a l pairs are trapped i n MDMA when i t i s subjected to lnonizing radiation at 77 K. The ESR measurements of MDMA at 77 Κ after warming at 195 Κ for 5 min showed that the radical pairs disappear during the heat-treatment but the spectral pattern of the isolated radical does not change though i t s intensity decreases s l i g h t l y (15). The ESR spectrum i l l u s t r a t e d i n Figure 2a i s the one obtain­ ed on measurements at 77 Κ after the heat-treatment at 195 K. With increasing temperature from 77 Κ to 193 Κ the pattern changes gradually and at 193 Κ i t became the t r i p l e t with an intensity of 1:2:1 and with a coupling constant of 26.5 gauss(Figure 2b). The spectral pattern changed when the ESR spectra were recorded at different orientations o the hyperfine s p l i t t i n g i lowered again to 77 R the spectral pattern returned to that of Figure 2a. These phenomena were precisely reproduced when temper­ ature was increased and decreased repeatedly. The t r i p l e t changed gradually to the 12-line spectrum ascribed to the uncyclic propa­ gating radical(IV) on further increase i n temperature as shown i n Figures 2c and 2d. The 3-line spectrum i s due to the interaction between an unpaired electron and two protons, and accordingly, i s ascribed to the 5-membered cyclic radical(III). The temperature dependence of the spectral pattern i s interpreted as restricted ro­ tation about the C-C bond of >C-CH2 group at lower temperature and i t s free rotation at higher temperature. To confirm this as­ signment ESR spectra of irradiated MDMA-d4 were measured. If the 3-line spectrum i s due to the 5-membered cyclic radical(III), the radical(VI) should be observed i n the case of MDMA-d4, and i t s gives a 5-line spectrum based upon the interaction between an un#

CH.

CH. -CD -C2

•C-CD ·

I

2

VI

-CD

β 'α

--c?

Ι

CH„ 1

C«CD„ σ-

I

VII

paired electron and two deuteriums as shown i n Figure 3c. The coupling constant i s predicted to be 4.1 gauss. The results ob­ tained by the ESR measurements at the same orientation of crystal as that of MDMA are i l l u s t r a t e d i n Figure 3. The big difference between the ESR spectra of MDMA(Figure 2) and MDMA-d^(Figure 3) indicates that the methylene protons of the methacryl groups are responsible for the spectra i n Figure 2. In accordance with our consideration, the quintet with a s p l i t t i n g constant of 4.0 gauss was detected at higher temperature(Figure 3b). The spectral change between a and b i n Figure 3 indicates the free rotation about the C-C bond of >C-CD2* group at higher temperature and re-

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

112

POLYMERS WITH CHAIN-RING

STRUCTURES

Figure 2. ESR spectra of MDMA single crystal irradiated at 77 Κ to 5.34 Mrad and heat-treated for 5 min at 195 K. The magnetic field is parallel to the c* axis in the b'c* plane, and recorded at 77 Κ (a), 183 Κ (b), 213 Κ (c), and 243 Κ (d). Spectra b, c, and d were measured after heating to the respective temperature for 20 min. Sensitivity of the instrument was kept constant except for the measurement of spectrum d.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

9.

KODAiRA ET AL.

^-Substituted Dimethacrylamides

113

10 G

Figure 3. ESR spectra of MDMA-a single crystal measured at the same orienta­ tion as that of MDMA in Figure 2 after the irradiation at 77 Κ to 5.34 Mrad and subsequent warming to 195 Κ for 5 min, and recorded at 77 Κ (a) and 183 Κ (b). Spectra d and e were observed at 77 Κ after heat-treatment at 213 Κ and 243 K, respectively, for 5 min. Diagrams c and f are predicted patterns for b and e, respec­ tively. Sensitivity of the instrument was kept constant except for the measurement of spectrum e. k

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

114

POLYMERS WITH CHAIN-RING

STRUCTURES

stricted rotation at lower temperature. On further increase i n temperature the quintet changed gradually to a 12-line spectrum (Figures 3d and 3e). If we assume that the two β-deuteriums of the methylene group of radical VII take the same conformations as those of two β-methylene protons of the uncyclic propagating radical(IV) of MDMA, the 12-line spectrum i s attributable to the uncyclic pro­ pagating radical(VII) based upon the following consideration. ESR studies of irradiated MDMA showed that the angles between the ir-orb i t a l and the projection of the two C^-H bonds along the C -Cg bond of radical(IV) are 0° and 120°, respectively, and accordingly, each deuterium should give rise to coupling constants of 6.1 and 1.5 gauss. The latter s p l i t t i n g i s considered to be too small to be observed due to line broadening i n present experimental condi­ tions. Therefore, each component of the quartet produced by the freely rotating methyl grou t r i p l e t with a coupling intensity. The 12-line spectrum i l l u s t r a t e d as a stick diagram i n Figure 3f should be observed. I t agrees well with 12-line spec­ trum obtained from irradiated MDMA-d^ as shown i n Figure 3e. The 12-line spectra i n Figures 2 and 3 are not seen at lower temperature although sensitivity of the instrument was kept con­ stant during these measurements. These facts suggest that uncyclic propagating radicals were formed during the heat-treatment. The intensities of the 12-line and 3-line spectra of Figure 2 were plotted against temperature from 183 Κ to 263 Κ i n Figure 4. The total amount of radicals and the quantity of the 5-membered c y c l i c radical decrease with increasing temperature, but the 12-line which was not observed at 183 R appears, and i t increases i t s intensity and then decreases. Figure 4 shows that the intermolecular reac­ tion between the 5-membered cyclic radical (III) and a MDMA molecule occur β at the temperature range from 183 R to 263 K. MDMA molecule can take various conformations. The distance between the two intramolecular double bonds i s rather long i f i t takes an extended structure. Such a conformation i s unfavorable a

?

I Me J Me J ?I f

C3

,

H-^ ^C2

C2 ^

I 0

C 3

^H

B-CH · 2

I

f

*ci^ ^cii N

0

IX

I VIII Me Me-Methyl group for cyclization reaction at 77 Κ because of the restricted rotation about chemical bonds. Therefore, i t i s interesting to know the molecular structure of MDMA i n crystalline l a t t i c e . A cryetallographic study of MDMA revealed that the distance between the carbon atoms C2 and C2 (VIII) i s 2.909 Â, and i t i s the shortest one among the distances between possible reaction sites (17). This result ,

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

KODAiRA ET AL.

180

1

N-Substituted Dimethacrylamides

200

220

240

260

Temp , Κ Figure 4. Variation of radical concentration [R-] trapped in MDMA irradiated at 77 K to 5.34 Mrad, and recorded at each temperature after heat-treatment for 20 min. Key: C , 3-line; ·, 12-line; and O, total concentration.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

116

POLYMERS WITH CHAIN-RING STRUCTURES

suggests that the formation of 5-membered ring i s the most favor­ able reaction i n the solid state of MDMA* It can not be said any­ thing from the ESR spectra of Figures 2a and 2b on the structure of the part written as Β i n Scheme IX except the fact that i t does not contribute to the hyperfine structure of ESR. However, this crystallographic study supports the assignment of the t r i p l e t to the monomeric 5-membered cyclic radical(III). It appeared that temperature lower than 77 Κ i s required to observe i n i t i a t i o n rad­ i c a l i n the solid state cyclopolymerization of MDMA. ESR Studies of PDMA, PDMA-d&. and BDMA. To see the effect of the eubstituente on nitrogen of RDMA and the phases where the re­ actions are carried out, ESR spectra of irradiated PDMA and BDMA were investigated. These monomers are favorable for this purpose because they form glassy supercooled l i q u i d and solid states de pending on the condition polycrystalline PDMA give constant of about 20 gauss as shown i n Figure 5a. With increasing temperature from 77 Κ to 193 Κ the central line of the t r i p l e t sharpens strongly, leaving the side bands almost unaltered(Figure 5b). When temperature was lowered to 77 Κ the spectral pattern returned to that shown i n Figure 5a. These phenomena were essen­ t i a l l y the same as those observed i n the irradiated single crystal of MDMA. Therefore, the 3-line spectrum i n Figure 5a i s attribut­ able to the 5-membered cyclic radical(III). ESR spectrum of i r r a ­ diated PDMA-d^ i s shown i n Figure 5c. I t does not show hyperfine structure, but the large difference between Figures 5a and 5c i n ­ dicates that the methylene protons of methacryl groups are closely related to the active species. When temperature was increased to 193 Κ the quintet with a coupling constant of 4.0 gauss was detect­ ed (Figure 5d). The hyperfine s p l i t t i n g i s considered to be due to the interaction between an unpaired electron and two deuteriums. The spectrum i l l u s t r a t e d i n Figure 5c reappeared when ESR was mea­ sured again at 77 Κ. These spectral change just corresponds to what has been observed i n irradiated MDMA-d^ and the active species which yields these spectra i s ascribed to the 5-membered cyclic radical(VI). Glassy PDMA irradiated at 77 Κ contains the anion radical of methacryl group which affords 3-line spectrum with a coupling con­ stant of 11 gauss. This anion radical could be bleached at 77 R by UV-light(21). ESR spectrum obtained after photo-bleach i s shown i n Figure 6a. When temperature was raised, i t s pattern changed to that depicted i n Figure 6b. Central part decreases i t s intensity as temperature i s lowered(Figure 6c). This temperature dependence of spectral pattern i s very similar to that observed i n crystalline MDMA and PDMA. Thus, the radical which yields these ESR spectra i s ascribed to the 5-membered cyclic radical(III). PDMA-d^ i n glassy state yields spectra shown i n Figures 6d-6f. These spectra were recorded after photo-bleach at 77 R. I t i s d i f f i c u l t to identify these spectra, but they clearly show that

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

d

Figure 5.

ESR spectra of polycrystalline PDMA and PDMA^ irradiated at 77 Κ to 5.34 Mrad. Recorded at 77 Κ (a,c) and 193 Κ (b,d).

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

118

POLYMERS WITH CHAIN-RING

STRUCTURES

a

Figure 6. ESR spectra of glassy PDMA and PDMA-â^ bleached by UV-light after the irradiation at 77 Κ to 5.34 Mrad, and recorded at 77 Κ (a,d) and 163 Κ (b,e). Spectra c and f were observed at 103 Κ after the measurement at 163 K.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

9. KODAiRA E T AL.

^-Substituted Dimethacrylamides

119

the methylene protons of methacryl groups are responsible for the spectra i n Figures 6a and 6b and support their assignment to 5membered cyclic radical(III). BDMA irradiated at 77 Κ i n the s o l i d state contains some un­ known species, judging from the spectrum shown i n Figure 7a. How­ ever, i t disappears on Increasing the temperature of the system and spectrum shown i n Figure 7b was observed at 173 K. This spec­ trum changes to the pattern given i n Figure 7c on measurement at 103 K. This spectral change between Figures 7b and 7c i s revers­ i b l e , depending on temperature. ESR spectra of glassy BDMA are depicted i n Figure 8. They are taken after photo-bleach at 77 R because an anion radical of methacryl group was detected. ESR spectra of BDMA i n crystalline and glassy state and their tempera­ ture dependence just correspon and glassy PDMA, respectively that 5-membered cyclic radical(III) i s formed i n both glassy and crystalline states of BDMA irradiated at 77 K. Conclusion A l l these results show that cyclization reaction occurs at 77 R i n the three substituents studied. Crystal data of MDMA t e l l us that the formation of 5-membered ring i s the most favorable reac­ tion i n the crystalline state of MDMA(17). Based upon this result PDMA and BDMA are considered to have favorable conformation for the cyclization to form 5-membered cyclic radical(III) i n both the crystalline and glassy states. To detect the i n i t i a t i o n radical (II) irradiation and ESR measurements have to be carried out at lower temperature than 77 R.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

120

POLYMERS WITH CHAIN-RING

STRUCTURES

Figure 8. ESR spectra of glassy BDMA bleached by VV-light after the irradiation at 77 Κ to 5.34 Mrad, and recorded at 77 Κ (a) and 193 Κ (b). Spectra c was ob­ served at 103 Κ after the measurement at 193 K.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

9.

KODAiRA ET AL.

^-Substituted Dimethacrylamides

121

Acknovlegements The Grant-in-Aid for individual research(365322) from the Ministry of Education, Japan, is acknowledged. A part of this work was done under the Visiting Researchers Program of Ryoto University Research Reactor Institute. 9

Literature Cited 1. Sokolova, T. Α.; Rudkovskaya, G. D. Vysokomol. Soedin. 1961, 3, 706. 2. Götzen, F.; Schröder, G. Makromol. Chem. 1965, 88, 133. 3. Azori. M.; Plate, Ν. Α.; Rudkovskaya, G. D.; Sokolova, Τ. Α.; Kargin, V. A. Vysokomol. Soedin. 1966,8,759. 4. Butler, G. B.; Myers, G. R. J. Macromol. Sci. Chem. 1970, A5, 135 5. Kodaira, T.; Aoyama 12, 897. 6. Kodaira, T.; Aoyama, F.; Morishita, K.; Tsuchida, M.; Nogi, S. Kobunshi Ronbunshu, 1974, 31, 682. 7. Kodaira, T.; Niimoto, M.; Aoyama, F.; Yamaoka, H. Makromol. Chem. 1978, 179, 1791. 8. Kodaira, T.; Sakai, M.; Yamazaki, K. J. Polym. Sci. Polym Lett. Ed. 1975, 13, 521. 9. Kodaira, T.; Ishikawa, M.; Murata, O. J. Polym. Sci. Polym. Chem. Ed. 1976, 14, 1107. 10. Kodaira, T.; Yamazaki, K.; Kitoh, T. Polym. J. 1979, 11, 377. 11. Kodaira, K.; Murata, O.; Edo, Y. J. Polym. Sci. Polym. Lett. Ed. 1980, 18, 737. 12. Aso, C.; Tagami, S.; Runitake, T. J. Polym. Sci. Part A-l, 1969,7,497. 13. Corfield, G. C.; Crawshaw, A. J. Polym. Sci. Part A-1, 1969, 7, 1179. 14. Casorati, E.; Martina, Α.; Guaita, M. Makromol. Chem. 1977, 178, 765. 15. Kodaira, T.; Morishita, K.; Yamaoka, H.; Aida, H. J. Polym. Sci. Polym. Lett. Ed. 1973, 11, 347. 16. O'Donnell, J. H.; McGarvey, B.; Moravetz, H. J. Amer. Chem. Soc. 1964, 86, 2322. 17. Higuchi, T. Private communication. 18. Rudkovskaya, G. D.; Sokolova, T. A. Zh. Org. Khim. 1966, 2, 1220. 19. Mannich, C.; Ritsert, K. Chem. Ber. 1924, 57, 1116. 20. Kurita, Y. Nippon Kagaku Zasshi, 1964, 85, 833. 21. Kodaira, T. Unpublished results. RECEIVED

February 1, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

10 Mössbauer Studies of Polymers from 1,1'-Divinylferrocene G. C. CORFIELD, J. S. BROOKS, and S. PLIMLEY Sheffield City Polytechnic, Sheffield S1 1WB, England

Linear, saturated, polymers obtained by radical initiation of 1,1'-divinyl parameters (δ, 0.23 ted for cyclopolymers with three-carbon bridged ferrocene units in the main chain. However, cationic initiation yields polymers which exhibit differences from the radical polymers in Mossbauer (δ, 0.27 mm s ; ΔEQ, 2.40 mm s ) and other spec­ troscopic studies. The cationic polymers may con­ tain a bicyclic unit or a ladder structure in the chain. -1

-1

The use of modern spectroscopic methods can reveal infor­ mation on the microstructures of cyclopolymers which previously went undetected (1J. Here we report the application of Mossbauer spectroscopy to a study of the polymers of 1,Γ-divinylferrocene (DVF). The polymerisation of DVF was first investigated by two independent research groups (£-7) who reported that soluble polymers could readily be obtained using free radical and cationic initiators. These authors proposed that cyclopolymerisation had occurred with the formation of linear polymers having three-carbon bridged ferrocene units (I), and some acyclic units (II), in the chain. Evidence for structure (I) as the predomi­ nant unit in the polymer chain was provided by the low level of vinyl unsaturation detectable by NMR or infrared spectroscopy and the observation that bands attributable to a bridged ferro­ cene (8) were to be found in the infrared spectra of these polymers. Recent investigations (9, 10) of bridged ferrocenes by Mossbauer spectroscopy have Hemonstrated that a short threecarbon bridge causes changes in the iron-ring geometry which leads to differences in Mossbauer parameters between threecarbon bridged ferrocenes and compounds with four- or fivecarbon bridges. We have re-investigated the polymerisation of 0097-6156/82/0195-0123$06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

124

POLYMERS WITH CHAIN-RING

STRUCTURES

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

10.

Polymers from 1

CORFIELD E T A L .

,Γ-Divinylferrocene

125

DVF and s t u d i e d the polymers by Mossbauer spectroscopy, using the isotope Fe-57, to seek supporting evidence f o r the t h r e e carbon bridged u n i t (I) as the predominant u n i t i n the c h a i n . Experimental DVF was prepared from ferrocene by e s t a b l i s h e d procedures (2, 3, 4 , 11_, 12, 1_3), r e c r y s t a l l i s e d from methanol (m.p. 3 9 . 5 4T.0 ° c y , and sRbwn to be pure by t h i n l a y e r chromatography ( s i l i c a gel with toluene as e l u e n t ) . Polymerisations using f r e e r a d i c a l and c a t i o n i c i n i t i a t o r s were c a r r i e d out e s s e n t i a l l y as described by Kunitake et al ( 2 ,

1* Vin s ' F e Mossbauer s p e c t r s t a n t a c c e l e r a t i o n spectromete v e l o c i t y d r i v e waveform. A 10 m Ci ' F e i n Pd source was used and a l l experiments were c a r r i e d out a t room temperature. The spectrometer was c a l i b r a t e d between runs using the magnetic s p l i t t i n g o f enriched F e absorber f o i l . The data were f o l d e d to determine the zero v e l o c i t y p o s i t i o n and the f o l d e d data were f i t t e d with L o r e n t z i a n f u n c t i o n s by a n o n - l i n e a r l e a s t squares f i t t i n g program ( 1 4 ) . 5

5 7

Results and Discussion Polymerisation. DVF has been polymerised using r a d i c a l and c a t i o n i c i n i t i a t o r s , and t y p i c a l r e s u l t s are given i n Table I. Radical i n i t i a t i o n i n d i l u t e s o l u t i o n s gave products which were predominantly s o l u b l e i n benzene. C a t i o n i c i n i t i a t i o n r e s u l t e d i n higher c o n v e r s i o n s , again mainly to s o l u b l e polymers. These r e s u l t s , which are s i m i l a r to those obtained by Kunitake et al (2 2» i ) , i n d i c a t e that l i n e a r polymers, p o s s i b l y c y c l o p o l y ­ mers, have been o b t a i n e d . 9

TABLE I POLYMERISATION OF 1,1 -DIVINYLFEPROCENE 1

Initiator/ mol.dm~3

Monomer mol.dm~3

Solvent

AIBN/ 1.56x10-3

0.10

C

BF,.0EW

0.20

CH C1

0.01

H

fi 6 0 0 2

2

Temp °C

11

Conversion % Soluble, % Insoluble

0

64

50

3

0

48

16

£

P r e c i p i t a t e d i n t o methanol Solubility

i n benzene

Infrared Spectroscopy.

The i n f r a r e d spectra o f the poly

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

126

POLYMERS WITH CHAIN-RING STRUCTURES

mers (Figure 1) were i n accord with previous work ( £ , 3, 4 ) . Of p a r t i c u l a r i n t e r e s t i n the spectrum o f the polymers obtained by r a d i c a l i n i t i a t i o n [PDVF(radical)] are the d i s t i n c t bands a t 810 cm"' and 850 c m " , which have been observed i n a large number o f heterobridged ferrocene compounds ( 8 ) . This p a i r o f c h a r a c t e r i s t i c bands i s not c l e a r l y seen i n the polymers obtained by c a t i o n i c i n i t i a t i o n [PDVF(cationic)] where a broad a b s o r p t i o n , centred a t approximately 830 c n H , i s observed. Other d i f f e r ences between the spectra can be seen, p a r t i c u l a r l y i n the fingerprint region o f the spectrum. These d i f f e r e n c e s have been i n t e r p r e t e d (2^, 3, 4) as due to d i f f e r e n c e s i n the extent o f c y c l i s a t i o n i n tfie polymers. However, an a l t e r n a t i v e e x p l a n a t i o n i s that t h i s i n d i c a t e s that the polymers have s i g n i f i c a n t l y different structures. 1

NMR Spectroscopy. Th (Figure a) were a l s o s i m i l a r to those p r e v i o u s l y p u b l i s h e d . The spectrum o f PDVF ( r a d i c a l ) contained no detectable v i n y l u n s a t u r a t i o n , whereas that o f PDVF ( c a t i o n i c ) showed a s i g n i f i cant amount o f u n s a t u r a t i o n , but c o n s i d e r a b l y l e s s than that expected i f one v i n y l group remained unreacted on each ferrocene unit. However, i t i s o f i n t e r e s t t h a t the s i g n a l a s c r i b e d by Kunitake et al {2, 3, 4) to v i n y l unsaturation i s a s i n g l e broad peak a t 65.90 ppm r a t h e r than the p a i r o f s i g n a l s expected a t approximately 64.9 and 6.1 ppm f o r a v i n y l s u b s t i t u e n t on a ferrocene r i n g . A l s o , the a l i p h a t i c protons patterns are d i f f e r ent f o r PDVF ( r a d i c a l ) and PDVF ( c a t i o n i c ) . Kunitake et al observed t h i s and a t t r i b u t e d i t to a d i f f e r e n c e i n polymer conformations, i n f l u e n c e d by the degree o f c y c l i s a t i o n . Again, an a l t e r n a t i v e explanation i s that the polymers are s t r u c t u r a l l y different. 13c NMR s p e c t r a o f these polymers (Figure 3) a l s o e x h i b i t c l e a r d i f f e r e n c e s , which support our suggestion that the p o l y mers are s t r u c t u r a l l y d i f f e r e n t . A d e t a i l e d a n a l y s i s and d i s cussion o f the C NMR spectra w i l l appear i n a subsequent publication. 1 3

Mossbauer Spectroscopy. Mossbauer s p e c t r o s c o p i c s t u d i e s o f the polymers are reported here, and these provide the evidence to s u b s t a n t i a t e the s t r u c t u r a l d i f f e r e n c e s between the polymers. The Mossbauer e f f e c t can be used to compare nuclear t r a n s i t i o n energies i n two m a t e r i a l s with high p r e c i s i o n . This i s usef u l i n o b t a i n i n g chemical information as the nucleus i s s e n s i t i v e to changes i n i t s e l e c t r o n i c environment. Two hyperfine i n t e r a c t i o n s which give r i s e to information about the e l e c t r o n i c environment are isomer s h i f t (IS) and quadrupole s p l i t t i n g (QS). Figure 4 shows a Mossbauer spectrum, t y p i c a l o f that obtained from ferrocene compounds, with these two parameters d i s t i n guished. IS r e s u l t s from the e l e c t r o s t a t i c i n t e r a c t i o n between the charge d i s t r i b u t i o n o f the nucleus and those e l e c t r o n s which

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

10.

CORFIELD E T A L .

Polymers from 1

,Γ-Divinylferrocene

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

127

128

POLYMERS WITH CHAIN-RING

STRUCTURES

I 8: S "S

S 1

s "ο S S-

I

· PP » 2 , 93.87; C , 149.51. Mass spectrum (m/e, d

f

b e n z e n e

r

o

m

s

c

1

2

5

4

1

m

c

=

5

peaks at 162 ( M , +

(86.1), 81 (20.3), 65 (20.3), 28 (41.9).

11.6), 134 (100), 121

l,2-Bis(ethenyloxy)-4-methylbenzene [ 2 ] . T h i s monomer was prepared by the same procedure as monomer 3. The physical data of monomer 2 are recorded as f o l l o w s : b.p. 55-56^0/0.75 mm. Yield: 58#7 A n a l . C a l c d . f o r C11H12O2: C, 74.12; H, 7.91. Found:

cm'

1

C, 75.14; H, 7.07, IR 1630, 950, (-0CH=CH ), 700 and 1590 2

(Ar).

PMR (CDC1-):

Ha, δ 6.36 (Q, J 6

Hz

>

J

gem =

2

Hz

δ 6.75 (d, 3H), 2.25 (S, 3H); p-vinoxyl,

= 6 Hz, J J

c

i

>>

$

Hb

>

δ

=

4

·

3

t

8

r

a

n

s

= 14 Hz), He, δ = 4.09 ( J

( trans = J

1

4

Hz

>

J

gem =

2

Η ζ

^»

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

c i s

=

12.

BUTLER

161

Macrocyclic Ring-Containing Polymers

AND LIEN

m-vinoxyl, Ha, 6.36 (Q, J

c

i

= 6 Hz, J

s

t

r

a

n

s

= 14 Hz), Hc, 4.27

( gem = « cis = >* * ' < trans = ' gem= >' CMR i n d -benzene from TMS, C j , 149-63 ppm; C , 120.47; C , J

2

H z

J

6

H z

H b

4

4

2

J

1

6

4

H

z

J

2 H z

2

128.00; CH

3

147.07; P C

4

at C , 20.60; C , 124.88; C , 119.94; C ( 4

e ( v i n y l )

5

,

g

93.69; m C g

m/e ( r e l a t i v e i n t e n s i t y ) 77 (30.9), 28 (58.3).

( v i n y l )

176 (M+,

,

93.11.

a

v i n y 1

)*

Mass spectrum:

22.3), 148 (100), 135 (77.3),

1,2-Bi s(2-ethenyloxyethoxy)benzene [ 1 1 ] . In a f l a s k , equipped with argon i n l e t , mechanical s t i r r e r and condenser with drying tube, was placed 60 g (0.55 mole) 99% pure catechol and 800 ml t-Bu0H. Potassiu to the r e f l u x i n g s o l u t i o placed with a p r e s s u r e - e q u i l i z i n g a d d i t i o n funnel through which 1.5 mole of 2 - c h l o r o e t h y l v i n y l ether was added to the s o l u t i o n , and the s o l u t i o n was r e f l u x e d f o r f i v e days. The s a l t was f i l ­ tered and washed three times with 1.5 1 petroleum e t h e r . The combined f i l t r a t e and e x t r a c t was condensed i n an evaporator. F r a c t . d i s t . (vac) qave 50 g product 11· b.p. 138-141°C/10- mm Hg. Y i e l d : 40%, m.p. 46-47°C. A n a l . C a l c d . f o r C H 0 : C, 4

1 4

1 8

4

67.18; H, 7.24. Found: C, 67.20; H, 7.20. IR (KBr) 975, 1610 (-0CH=CH ); 1190 (-CH 0CH -); 815, 720 (Ar) c n r l . PMR δ 6.85 (S, 2

2

4H), 4.05 (m, 2H);

Η

α

2

^ Η

χ

Χ

-0^

Η

β

β

Η at δ 6.48 ( q , J = 7 Hz, J = 14 H z ) , H and other p r o ­ tons 4.3-3.85 (m, 12H). Mass spectrum: m/e ( r e l a t i v e i n t e n s i t y ) , 250 (M , 11.8), 136 (86.6), 121 (47.9), 80 (22.2), 71 (25.1), 45 (100), 43 (78.2*), 41 (23.3), 28 (77.8*). α

c

i

s

t

r

a

n

s

$

+

l-t-Buty1-3,4-bis(ethenyloxyethoxy)benzene [12]. In a f l a s k , equipped with nitrogen i n l e t , mechanical s t i r r e r and con­ denser with a drying tube, was placed 32.2 g (0.2 mole) 4 - t b u t y l c a t e c h o l , 18.5 g (0.45 mole) NaOH and 600 ml n-butanol. A f t e r r e f l u x i n g 20 minutes to d i s s o l v e a l l NaOH, 53 g (0.5 mole) 2 - c h l o r o e t h y l v i n y l ether was dropped through a p r e s s u r e - e q u a l i z ­ ing a d d i t i o n funnel under N2. A f t e r 48 hours of r e f l u x i n g , nbutanol was removed i n a r o t a r y evaporator and the residue d i s ­ solved i n 300 ml H2O and extracted three times with 500 ml p e t ­ roleum e t h e r . The combined e x t r a c t was d r i e d over MgSÛ4 and condensed i n a r o t a r y evaporator. F r a c t . d i s t . (vac) gave 20 g of the d e s i r e d product. Y i e l d : 33%; b . p . 164-168°C/10-3 mm Hg. Anal. Calcd. for C H 0 : C, 70.59; H, 8.50. Found: C, 70.56; 1 8

2 6

4

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

162

POLYMERS WITH CHAIN-RING STRUCTURES

H, 8.55. cm" . 1

IR

(neat) 985, 1652 (-0CH-CH ); 815 ( A r ) ;

1200 (C-O-C)

2

PMR (CDC1 ), δ 6.85 3

( q , 3H), 6.45

( q , 2H, J

c

i

= 7 Hz,

s

trans ^ ^ '> (> ^· P ( r e l a t i v e i n t e n s i t y ) , 306 ( M , 2 9 . 3 ) , 177 (100), 71 ( 1 7 . 5 ) , (43.5), 43 ( 4 8 . 9 * ) , 41.25 (1).

J

=

1

4

H z

;

4

,

0

9

1 2 H

1

,

2

5

S

9 Η

M

a

s

s

s

e

c

t

r

u

m

:

m

+

Synthesis

of Model

/ 45 e

Compounds

2,3-Dimethyl-1,4-benzodioxane [3] [ 4 ] . Into a s t i r r e d s o l u ­ t i o n o f 62 g (1.1 mole) Κ0Η, 55 g (0.5 mole) catechol and 1.5 1 DMF i n a f l a s k , equipped with mechanical s t i r r e r , p r e s s u r e - e q u a l ­ i z i n g a d d i t i o n funnel and condenser with drying tube, was added a s o l u t i o n of 2,3-butanedio r i n g at room temperatur was mixed with twice the volume of water and extracted with twice the volume of d i e t h y l e t h e r . The e x t r a c t was d r i e d over anhy­ drous MgSÛ4 * condensed i n a r o t a r y evaporator. Fract. dist. (vac) gave 24 g mixture of c i s - [3] and t r a n s - 2 , 3 - d i m e t h y l - l , 4 benzodioxane [ 4 ] . Y i e l d : 29.23%. b.p. 96-100°C/6 mm. A n a l . Calcd. for C H 0 : C, 73.12; H, 7.36. Found: C, 73.27; H, 7.40. Repeated r e c r y s t a l l i z a t i o n from methanol gave 14 g of t r a n s 2,3-dimethyl-l,4-benzodioxane [ 4 ] . m.p. 73-74°C. Column chroma­ tography of the mother l i q u i d , using AI2O3 as adsorbent and a 1:1 mixture of petroleum ether and d i e t h y l e t h e r as e l u e n t , and then f r a c t i o n a l d i s t i l l a t i o n under vacuum gave 9 g of pure c i s - 2 , 3 dimethyl-l,3-benzodioxane [ 3 ] . b.p. 9 6 ° C / 3 . 5 mm. PMR c i s - i s o m e r [ 3 ] : δ 1.3 ( d , J = 6 Hz, 6H), 3.81 (M, 2H), 6.80 (S, 4H). trans-isomer [ 4 ] : δ 1.20 ( d , J = 7 Hz, 6H), 4.18 (m, 2H), 6.72 (S, 4H). IR: (No major d i f f e r e n c e between 3 and 4) 1600 cm-1, 750 cm-1 ( A r ) , 940 cm-1, 1085 cm-1, 1265 cm-1 (ftr-0-C). CMR d a t a : see Table I. Mass spectrum: m/e ( r e l a t i v e i n t e n s i t y ) , [ 4 ] , 164 (M+, 9 0 . 8 ) , 135 ( 5 6 . 3 ) , 110 (100), 80 ( 3 2 . 0 ) , 55 ( 3 6 . 4 ) , 28 (31.3). a n c

9 n

d

U

1 9

i

a

9

ά

c i s - and trans-2,4-Dimethyl-l,5-benzodioxepane [5] [ 6 ] . These compounds were prepared by s i m i l a r methods as used f o r 3 and 4 using 2,4-pentanediol as s t a r t i n g m a t e r i a l . Anal. Calcd. for C H 0 : C, 74.12; H, 7.91. Found: C, n

1 4

2

74.31, H, 8.05. (2S, 4R)-Dimethyl-l,5-benzodioxepane [ 5 ] . 114-116°C, a white f l a k e c r y s t a l . PMR: δ 1.38 6H): 1.92 (m, 2H), 3.9 (m, 2H), 6.95 (S, 4H). II. Mass spectrum: m/e ( r e l a t i v e i n t e n s i t y ) , 121 ( 7 6 . 2 ) , 110 (100), 69 ( 5 4 . 1 ) , 41 (61.5). (2S, 4S)-Dimethyl-l,5-benzodioxepane [ 6 ] . 110°C/5 mm. PMR: δ 1.35 ( d , J = 6.5 Hz, 6H),

Y i e l d : 6%. m.p. ( d , J = 6.5 Hz, CMR: See Table 178 ( M , 4 5 . 7 ) , +

Y i e l d : 3%. 1.95 ( q , J ^ t

n

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

ç

b.p. =

12.

BUTLER

163

Macrocyclic Ring-Containing Polymers

AND LIEN

9 Hz, J , CIS

= 7 Hz, 2 Η ) , 4.55 (m, 2H), 6.82 (S, 4H).

Table II.

IR:

CMR:

See

4 (No major d i f f e r e n c e between !5 and 6 ) , 1580 cm" ,

750 ( A r ) , 930 c m " , 1255 c m " Polymerization Studies 1

1

(Ar-O-C).

One r e p r e s e n t a t i v e example o f each polymerization i s given to i l l u s t r a t e the general procedures. Radical Polymerization of 1,7-Dienes 1 and 2. Charged to a 300 ml polymer t h i c k - w a l l g l a s s tube were 24 g (0.148 M) monomer 1, 250 ml benzene (0.5 M) and 1.9 g (7.84 χ 10"3 M, 4%) benzoyl peroxide. The polymer tube was connected to a high vacuum l i n e , frozen i n a dry i c e - a c e t o n s o l u t i o n was subjected t before the polymer tube was sealed under vacuum. The sealed tube was placed i n an o i l bath a t 60°C f o r one week. The s o l u t i o n r e ­ mained c l e a r but became v i s c o u s . The polymer [9] was p r e c i p i ­ tated as a white powder by pouring the s o l u t i o n i n t o methanol, f i l t e r e d and r e d i s s o l v e d i n benzene and r e p r e c i p i t a t e d from methanol three times before i t was d r i e d in__a vacuum p i s t o l at 60°C f o r three days. Conversion was 31%. M = 2.1 χ 1 0 g/mole. Anal. Calcd. f o r C H 0 : C, 74.05; H, 6.20. Found: C, 73.90; H, 6.17. 3

n

l n

Α

ϋ

i n

A

U

o

ά

C a t i o n i c Polymerization o f 1 7 - D i e n e s . A 500 ml t h r e e necked, round-bottomed f l a s k , equipped with a gas i n l e t , mechani­ cal s t i r r i n g bar and septum, was flamed and d r i e d under argon. In the f l a s k were placed 5 g (0.0308 M) monomer J. and 480 ml CH C1 (0.064 M) and then 0.1477 (1%) CSbF under argon. The ?

2

2

3

6

red brown s o l u t i o n was s t i r r e d at room temperature f o r 38 hours. At the end o f the p o l y m e r i z a t i o n , a few ml o f ammonia-methanol was added to terminate the p o l y m e r i z a t i o n . The polymer [7] was p r e c i p i t a t e d by pouring the s o l u t i o n i n t o methanol. It was r e d i s s o l v e d i n acetone and r e p r e c i p i t a t e d from petroleum e t h e r , then d r i e d in a vacuum p i s t o l at 60°C f o r three days. Conver­ s i o n , 67%. M = 6.07 χ 1 0 g/mole. The benzene skeleton s t r e t c h i n g of compounds 5 and 16, sevenmembered r i n g model compounds, occurred a t 1580 c m " i n IR, while that o f six-membered r i n g model compounds 3 and 4 absorbed at 1600 c m " i n IR. The IR of polymer 1_ from c a t i o n i c p o l y m e r i z a ­ t i o n had a peak at 1580 c m " but none at 1600 c m " , while that of polymer 9 from r a d i c a l polymerization had a peak a t 1600 c m " but none at 1580 cm-1. Only the general s i m i l a r i t y between the PMR spectra o f p o l y ­ mers and that o f model compounds was observed because the peaks were broad and poorly d e f i n e d . However, CMR d i d give d e t a i l e d and c l e a r - c u t information about the polymer s t r u c t u r e s . (Compare the data of Tables I-IV.) 3

n

1

1

1

1

1

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

164

POLYMERS WITH CHAIN-RING STRUCTURES

C a t i o n i c Polymerization of 1,13-Dienes 11 and 12. By a p r o cedure analogous to that used f o r 1,7-dienes, the 1,13-dienes were polymerized v i a c a t i o n i c i n i t i a t i o n . Conversion to 13: 90%. Anal. Calcd. f o r C H 0 . : C, 67.18, H, 7.24. Found: C, 66.94; H, 7.29. , The IR absorptions of the v i n y l o x y group at 1610 cm and 975 c m " were completely absent i n the spectrum of polymer 13. Instead, peaks at 740 c m " and 1595 c m " from benzene r i n g , 920, 1120 and 1260 cm-1 f m C-0-C were observed. PMR s p e c t r a showed three peaks, aromatic protons at 6 6.9, protons of carbon a d j a ­ cent to oxygen at δ 4.0 and saturated a l i p h a t i c protons at δ 1.80 but no v i n y l i c protons at δ 6.2. The i n t e g r a t i o n r e s u l t s agreed well with the numbers of d i f f e r e n t protons. CMR showed complete absence of v i n y l o x y carbons at 86.82 ppm, but the saturated a l i ­ p h a t i c backbone carbons n / !

1

4

1 Q

1

8

4

1

1

1

r 0

Copolymerization of MA and 1,7-Diene 1. Charged to a 300 ml t h i c k g l a s s wall polymer tube were 4 g (0.025 mole) monomer l 4.8 g (0.049 mole) MA, 0.080 g (2%) AIBN and 200 ml (0.45 M) c y clohexanone. A f t e r i t was subjected to three c y c l e s of f r e e z e thaw degassing processes and sealed under high vacuum, i t was placed i n an o i l bath at 70°C f o r 23 hours. The s o l u t i o n r e ­ mained c l e a r but became v i s c o u s . At the end of the p o l y m e r i z a ­ t i o n t i m e , the polymer was p r e c i p i t a t e d by pouring the s o l u t i o n i n t o n-hexane, washed thoroughly with d i e t h y l e t h e r and d r i e d at 90°C under vacuum f o r 48 hours. Conversion, 15: 34%. M : 1900 g. A n a l . C a l c d . f o r CjgHj^Og (a p e r f e c t 1:2 a l t e r n a t i n g s t r u c ­ ture): C, 60.34; H, 3.94. Found: C, 62.14; H, 4.43. It was s o l u b l e i n acetone, cyclohexanone, chloroform and DMF. The IR spectra of the polymers [15 and 16] showed absorp­ t i o n s f o r the c y c l i c anhydride u n i t at 1780 and 1850 c m " , the benzene r i n g at 760 and 1590 c m " and ether linkage at 1230 and 920 c m " , but no absorptions of the v i n y l o x y group at 960 and 1640 c m " . PMR s p e c t r a a l s o showed the aromatic protons at δ 7.0, the protons of carbons next to oxygen at δ 4.0 and the saturated a l i p h a t i c protons at δ 1.2. 9

n

1

1

1

1

Copolymerization of MA and 1,13-Diene 11. Charged to a 100 ml t h i c k g l a s s wall polymer tube were 2 g (0.008 M) monomer j l , I. 824 g (0.016 M) MA, 0.0263 g (2%) AIBN and 60 ml cyclohexanone. The remainder o f the procedure was analogous to that used f o r c o ­ polymerization of 1^ with MA. Conversion to 17: 89%. M : 6060 g/mole. Anal. Calcd. for C 2 2 2 ° 1 0 * > C, 58.99; H, 5.09. It was s o l u b l e i n acetone, cyclohexanone, DMF and DMS0. n

H

:

C

5

9

e

l

9

;

H

4

e

9

6

e

F

o

2

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

u

n

d

:

12.

BUTLER

AND LIEN

Macrocyclic Ring-Containing Polymers

165

The IR spectrum o f polymer 17 when polymerized i n c y c l o h e x a none, showed the absorptions of c y c l i c anhydride at 1770 and 1860 c m , ether linkage at 1250 cm"* , benzene r i n g at 740 and 1590 c m " , and only a s l i g h t absorption o f ethenyloxy at 1615 cm" . PMR of the polymer showed aromatic protons at 6 6.75 and the protons of carbons adjacent to an oxygen at 6 3.9. No ab­ s o r p t i o n of v i n y l i c protons could be d i s t i n g u i s h e d from the background n o i s e . The MA content of polymer 17 was determined to be 65.71%, very c l o s e to the t h e o r e t i c a l 67% f o r a composition of a 1:2 r e g u l a r l y a l t e r n a t i n g cyclocopolymer of monomer U_ and MA. - 1

1

1

1

Literature Cited 1.

Butler, G.B.; Corfield mer Science"; Vol. New York, 1974; Ch. 3. 2. Barnett, M.D.; Crawshaw, Α.; Butler, G.B. J. Am. Chem. Soc. 1959, 81, 5946. 3. Marvel, C.S.; Garrison, W.E. J. Am. Chem. Soc. 1958, 80, 1740. 4. Yokota, K.; Kakuchi, T.; Takada, Y. Polym. J. 1976, 8(6), 495. 5. Chu, S.C.; Butler, G.B. Polym. Ltrs. 1977, 15, 277. 6. Seung, S.L.N.; Young, R.N. J. Polym. Sci., Polym. Ltrs. Ed. 1978, 16, 367. 7. Pederson, C.J. J. Am. Chem. Soc. 1967, 89, 7017. 8. Gatti, G.; Segre, A.L.; Morandi, C. Tetrahedron 1967, 23, 4385. 9. Fritz, J.S.; Lisichi, N.M. Anal. Chem. 1951, 23, 589. 10. Griffith, R.C.; Grant, C.M.; Roberts, J.D. J. Org. Chem. 1975, 40 (25), 3726. 11. Foster, R. "Organic Charge-Transfer Complexes"; Academic Press: New York, 1969; p. 20. 12. Butler, G.B.; Campus, A.F. J. Polym. Sci. 1970, A-l, 8, 545. 13. Pittman, C.U. Jr.; Rounsefell, T.D. Macromolecules 1975, 8 (1), 46. RECEIVED February 9, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

13 Radiation-Induced Loss of Unsaturation in 1,2-Polybutadiene MORTON A. GOLUB and ROBERT D. CORMIA

1

Ames Research Center, NASA, Moffett Field, CA 94035

An IR study was made of the radiation-induced loss of unsaturatio d methyl productio i 1,2-polybutadien the i n i t i a l vinyl content, decreased from ~550 for VB with 98.5% 1,2 initially, to ~270 for VB with 85% 1,2 initially. The latter G(-1,2) compares favorably with the value of 196 (von Raven and Heusinger, 1974) for VB with a stated 91.5% 1,2 double bonds (but 85% estimated in this work). G(-trans-1,4), which depends on the i n i t i a l vinylene content, ranged from ~21 for VB with 14% trans-1,4 to near-zero for VB with ) , whereas the h i g h l y c y c l i z e d VB, obtained by UV i r r a d i a t i o n or by heating under n o n p y r o l y t i c c o n d i t i o n s , and apparently a l s o by γ-irradiation, contains about one methyl group f o r every four v i n y l u n i t s consumed (3). Although ions and r a d i ­ c a l s are doubtless formed i n γ-irradiated VB ÇL,2), they are probably l e s s important than e x c i t e d double bonds (3) i n promoting the r a d i a t i o n - i n d u c e d l o s s of 1,2 u n s a t u r a t i o n culminating i n extensive c y c l i z a t i o n and some c r o s s l i n k i n g .

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

13.

GOLUB AND CORMIA

169

Radiation-Induced Loss of Unsaturation

Since there was only one IR spectrum of γ-irradiated VB i n the l i t e r a t u r e (1) s u i t a b l e f o r q u a n t i t a t i v e comparison w i t h the s p e c t r a o f U V - i r r a d i a t e d o r t h e r m a l l y - t r e a t e d VB ( 3 ) , we obtained new IR data on γ-irradiated VB. Our aim was to determine i f the growth of methyl groups with p r o g r e s s i v e l o s s o f v i n y l unsatura­ t i o n i n the r a d i a t i o n c y c l i z a t i o n of VB indeed conforms t o that of the corresponding photo- and thermal c y c l i z a t i o n s , o r i f i t f o l l o w s , i n s t e a d , that of the a c i d - c a t a l y z e d o r c a t i o n i c c y c l i z a ­ t i o n o f VB. Such i n f o r m a t i o n was expected to lead to a b e t t e r understanding of the mechanisms of the v a r i o u s c y c l i z a t i o n s of VB and of the r e s u l t i n g c y c l i z e d s t r u c t u r e s . Experimental Three samples o f VB (98.5% 1,2, 0.7% c i s - 1 . 4 M = 219,000; M /M = 1.08) and Polymer Β (90.1% 1,2, 3.9% c i s - 1 , 4 and 6.0% trans-1,4 double bonds; M = 270,000; M /M = 1.1), both k i n d l y s u p p l i e d by Dr. A. F. Halasa and Mr. J . E. H a l l , The F i r e s t o n e T i r e & Rubber Company, Akron, OH; and Polymer C (86.0% 1,2, ^14% trans-1,4 double bonds; M ^200,000; M /M ^2.0, with s t r u c t u r e and molecular weight s i m i l a r to those of von Raven and H e u s i n g e r s Polymer 6 ( 1 ) ) , obtained from I n s t i t u t Français du Pétrole, S o l a i z e , France. Most of the work was performed with Polymer A, w h i l e Polymers Β and C served to b r i d g e the gap between Polymer A and Polymer 6. The VB samples were p u r i f i e d by r e p r e c i p i t a t i o n from benzene s o l u t i o n with methanol as p r e c i p i t a n t . T h i n f i l m s of the p u r i f i e d VB samples, c a s t from benzene stock s o l u t i o n s onto NaCl d i s k s , were sealed i n vacuum i n Pyrex tubes and i r r a d i a t e d i n a Gammacell 220 C o source. IR s p e c t r a of the VB f i l m s before and a f t e r γ-irradiation were obtained with a Perkin-Elmer Model 180 spectrophotometer. Because e x c e s s i v e s c a t t e r was encountered i n determining r e s i d u a l 1,2 u n s a t u r a t i o n of the γ-irradiated f i l m s by means of the c h a r a c t e r i s t i c ll.O-pm band, an a l t e r n a t i v e method was f o l l o w e d : F i r s t , a c a l i b r a t i o n p l o t of A 7 1 / A Ç 9 v s percent 1,2 u n s a t u r a t i o n ( F i g u r e 1) was cons t r u c t e d from IR data on t h e r m a l l y - t r e a t e d VB f i l m s , where the r e s i d u a l v i n y l content was obtained as 100(An o ) J l l .o) » s u b s c r i p t s h and ο denoting absorbances of heated and unheated f i l m s , r e s p e c t i v e l y . The s u i t a b i l i t y o f the c a l i b r a t i o n p l o t i s shown by the f a c t that Α 7 χ / Α ς 9 v a l u e s f o r v a r i o u s polybutadienes with d i f f e r e n t v i n y l contents (Polymers EB, F I and DI of a p r i o r paper (6), with 48, 30 and 10% 1,2 u n i t s , r e s p e c t i v e l y , and Polymers Β and C of t h i s paper, a l l d e p i c t e d by squares i n F i g u r e 1) f i t w e l l on that p l o t . Second, the v a l u e of &7.I/&G.S was obtained f o r each γ-irradiated f i l m , and the percent 1,2 unsatura­ t i o n determined from F i g u r e 1. Changes i n the trans-1,4 content were estimated by means of the c h a r a c t e r i s t i c 10.3-ym peak. The methyl p r o d u c t i o n was estimated by the Ay^/Ag.g r a t i o as before Q.,6) . To compare the growth of methyl with l o s s of 1,2 unsaturan

w

n

n

n

w

n

w

n

1

6 0

A

t

β

t

n

Q

β

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

e

170

POLYMERS WITH CHAIN-RING STRUCTURES

3.5 r

PERCENT 1,2 UNSATURATION Figure I. Calibration plot for residual vinyl content in cyclized 12-polybutadiene. Values calculated for Polymers B, C, EB, FI, and DI with different initial vinyl contents are represented by • .

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

13.

GOLUB AND

Radiation-Induced Loss of Unsaturation

CORMIA

171

t i o n f o r the d i f f e r e n t c y c l i z a t i o n s , new p h o t o c y c l i z a t i o n s of VB were a l s o c a r r i e d out as d e s c r i b e d ( 3 ) . R e s u l t s and D i s c u s s i o n F i g u r e 2 shows that VB Polymer A undergoes pronounced radiâtion-induced l o s s of 1,2 u n s a t u r a t i o n ( i n d i c a t e d by decreased a b s o r p t i o n a t 11.0, 10.1, 7.1 and 6.1 ym, and increased a b s o r p t i o n at 6.9 ym) accompanied by formation of methyl groups (new band a t 7.3 ym) and n e g l i g i b l e change i n trans-1,4 u n s a t u r a t i o n (10.3 ym). The dashed l i n e s are b a s e l i n e s used to measure absorbances of the p e r t i n e n t bands. The s p e c t r a of Polymers Β and C were s i m i l a r to those shown i n F i g u r e 2 except f o r d i s p l a y i n g more intense 10.3-ym peaks i n i t i a l l y ( r e f l e c t i v e of t h e i r higher trans-1,4 contents) which experienced some d i m i n u t i o n on γ-irradiation The changes i n F i g u r e 2B, besides bein to) those observed i n th c y c l i z e d ) VB ( 3 ) , are q u a l i t a t i v e l y i d e n t i c a l t o those observed i n the IR spectrum o f von Raven and Heusinger's γ-irradiated VB Polymer 6 (see F i g u r e 4 i n Reference 1 ) , except f o r r e d u c t i o n of the trans-1,4 content i n Polymer 6 (and seen a l s o i n Polymers Β and C). F o r an kj i/Aç $ v a l u e of 0.247 i n F i g u r e 2B, and u s i n g the c a l i b r a t i o n p l o t of F i g u r e 1, we c a l c u l a t e d that the v i n y l content i n VB Polymer A decreased from an i n i t i a l 98.5% to ^20.8% 1,2 a f t e r a dose of 274 Mrad. Using the same &7.\/&ç> $ approach, we c a l c u l a t e d that the v i n y l content i n Polymer 6 decreased from an i n i t i a l 85% 1,2 (by our estimate, o r 91.5% as s t a t e d by von Raven and Heusinger (_1)) to ^31% 1,2 a f t e r a dose of 150 Mrad; we estimated a l s o that the trans-1,4 content correspondingly decreased from ^15% to ^6.7%. By way of comparison, the u n s a t u r a t i o n of our Polymer C decreased from 86.0% 1,2 and 14.0% trans-1,4 i n i t i a l l y to 42.8% 1,2 and 10.7% trans-1,4 a f t e r a dose of 43.3 Mrad. u

9

0

F i g u r e 3 presents a s u p e r p o s i t i o n of k i n e t i c data f o r the r a d i a t i o n - i n d u c e d l o s s of 1,2 u n s a t u r a t i o n i n VB, the data having been normalized f o r the d i f f e r e n t i n i t i a l v i n y l contents i n the v a r i o u s polymers. The r e s i d u a l unsaturation-dose data f o r Polymer A were p l o t t e d d i r e c t l y , y i e l d i n g the s o l i d l i n e shown; data f o r Polymers B, C and 6 were a r b i t r a r i l y p l o t t e d a t doses g r e a t e r than the a c t u a l doses by amounts equal to s h i f t f a c t o r s of 2.0, 2.7 and 3.0 Mrad, r e s p e c t i v e l y . These s h i f t f a c t o r s correspond to the doses r e q u i r e d to decrease the 1,2 u n s a t u r a t i o n of Polymer A from 98.5% i n i t i a l l y t o 90.1, 86.0 and 85.0% (the i n i t i a l v i n y l cont e n t s o f Polymers B, C and 6 ) , r e s p e c t i v e l y . By t h i s n o r m a l i z a t i o n procedure, the data f o r the three VB polymers used i n t h i s work (A, Β and C) and the s i n g l e data p o i n t a v a i l a b l e from the l i t e r a ­ ture (Polymer 6) could be f i t t e d t o a common k i n e t i c p l o t . From the i n i t i a l slope t o the s o l i d l i n e i n F i g u r e 3, GQ(-1,2) was found t o have the r a t h e r h i g h value of ^550. Taking the tangent to the l i n e a t 85% 1,2, we o b t a i n G . ( - l , 2 ) ^270, which compares 3

0

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

172

POLYMERS WITH CHAIN-RING

STRUCTURES

WAVELENGTH,^ m 6

1800

1600

7

1400

8

1200

9

10

1000

WAVENUMBER, CITT Figure 2.

12

15

800

20

500

1

IR spectra of 1,2-polybutadienefilm,Polymer A, before (top) and after (bottom) y-irradiation in vacuum to a dose of 274 Mrad.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

13.

GOLUB AND

Radiation-Induced Loss of Unsaturation

CORMIA

173

100 r

10h

I

0

1

1

50

100

ι

ι

150 200 DOSE, MRAD

ι

ι

ι

250

300

350

Figure 3. Superposition of kinetic data for radiation-induced loss of 1 ^-unsatura­ tion in polybutadiene with different initial vinyl content. Key: O, 98.5% unsatura­ tion; (D, 90.1% unsaturation; Θ , 86.0% unsaturation; and · , 85.0% unsaturation.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

174

POLYMERS WITH CHAIN-RING STRUCTURES

f a v o r a b l y w i t h a G(-l,2) = 196 reported f o r Polymer 6 ( 1 ) . The discrepancy between the l a t t e r v a l u e s i s no doubt due to the f a c t that G(-1,2) decreases very r a p i d l y w i t h l o s s of 1,2 u n i t s , e s p e c i a l l y i n the e a r l y p a r t of the c y c l i z a t i o n , thereby preventing a p r e c i s e determination of the r a d i a t i o n chemical y i e l d . In any case, the l a r g e G(-1,2) v a l u e s observed f o r l o s s of v i n y l double bonds i n VB imply a chain r e a c t i o n . However, i n s t e a d of accepting the proposed carbonium i o n (1) or r a d i c a l (2) c h a i n mechanisms, we p r e f e r the n o n i o n i c , n o n r a d i c a l "energy c h a i n " mechanism postul a t e d p r e v i o u s l y (3) f o r the thermal, photo- and radiâtion-induced c y c l i z a t i o n s of VB. We estimated G(-trans-1,4) to be ^21 f o r Polymer C. Von Raven and Heusinger 01) r e p o r t e d G ( - t r a n s - l , 4 ) = 107 f o r t h e i r v e r y s i m i l a r Polymer 6 e r r o r and should be o slopes of curves f o r l o s s of 1,2 and trans-1,4 i n t h e i r F i g u r e 5 and t h e i r v a l u e of G0-l,2) = 196). In any event, the G(-trans-1,4) f o r a VB c o n t a i n i n g ^14% trans-1,4 i s c o n s i d e r a b l y smaller than G(-1,2) f o r such a polymer, although somewhat l a r g e r than G(-1,4) ^8 f o r a high-1,4 polybutadiene (7). On the other hand, G(-trans-1,4) drops p r a c t i c a l l y to zero (as i t i s i n Polymer A) with decrease i n the i n i t i a l trans-1,4 content of VB. The quest i o n of the r e l a t i v e extents of r a d i a t i o n - i n d u c e d l o s s of 1,2 and 1,4 u n i t s i n polybutadienes c o n t a i n i n g d i f f e r e n t v i n y l / v i n y l e n e r a t i o s m e r i t s f u r t h e r study. The formation of methyl groups accompanying the r a d i a t i o n induced l o s s of 1,2 u n s a t u r a t i o n i n VB i s shown i n F i g u r e 4. The data p o i n t f o r γ-irradiated Polymer 6 ( f i l l e d c i r c l e , c a l c u l a t e d from F i g u r e 4 i n Reference 1) f a l l s i n l i n e with the data f o r γ-irradiation of Polymers A, Β and C (other c i r c l e s ) and does not f i t the dotted l i n e r e p r e s e n t i n g methyl formation i n the a c i d c a t a l y z e d or c a t i o n i c c y c l i z a t i o n of VB. To avoid c l u t t e r , data p o i n t s f o r the new photo- and thermal c y c l i z a t i o n s are not p l o t t e d i n F i g u r e 4, but are represented by the s o l i d and dashed l i n e s , r e s p e c t i v e l y . E v i d e n t l y , thermal c y c l i z a t i o n of VB produces some­ what more methyl groups f o r a given l o s s of v i n y l u n i t s than does photochemical c y c l i z a t i o n , w h i l e r a d i a t i o n c y c l i z a t i o n gives methyl r e s u l t s which overlap those f o r thermal and p h o t o c y c l i z a t i o n s . Since the c a t i o n i c a l l y c y c l i z e d VB i s regarded as p r e ­ dominantly monocyclic, with one methyl group formed f o r every two v i n y l double bonds consumed (.1,5), we i n f e r (3) from F i g u r e 4 that r a d i a t i o n c y c l i z e d VB contains about one methyl f o r every 4-5 v i n y l double bonds consumed. Since the IR s p e c t r a of photo- and radiâtion-cyclized VB are v e r y s i m i l a r , as are the corresponding r a t e s of methyl formation, the mechanism f o r c y c l i z a t i o n i s probably e s s e n t i a l l y the same f o r these two cases, i f not a l s o f o r the thermal case. The common denominator i s presumably i n i t i a l e x c i t a t i o n of the v i n y l double

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

GOLUB

A N D CORMIA

1.0

Radiation-Induced Loss of Unsaturation

175

r

.9 h

0

Figure 4.

20 40 60 80 100 PERCENT 1,2 DOUBLE BONDS CONSUMED

Methyl formation accompanying cyclization of VB. Key: O, radiation; , thermal; , photochemical; and · · ·, cationic cyclization.

The different circles have the same key as in Figure 3; the right and left squares were calculated from IR spectra in References 1 and 8, respectively.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

176

POLYMERS

WITH

CHAIN-RING

STRUCTURES

bonds (ensuant on a b s o r p t i o n of photons o r i n t e r a c t i o n with γ-rays or simple heat input) l e a d i n g t o t h e i r disappearance by c y c l o a d d i ­ t i o n (Reaction 3) with, a t most, a minor involvement of Reactions 1 and 2 i n the r a d i a t i o n case. Since r i n g c l o s u r e i n Reaction 3 i s exothermic (^50-80 kcal/mole, depending on s t r a i n energy i n the r e s u l t i n g b i c y c l o h e p t a n e s ) , the energy r e l e a s e d to the sur­ roundings could serve to e x c i t e another v i n y l double bond to undergo c y c l o a d d i t i o n (the a c t i v a t i o n energy f o r thermal c y c l i z a ­ t i o n being *v>34 kcal/mole), thereby propagating an "energy c h a i n " c y c l i z a t i o n C3). In any event, there i s no need to invoke the c a t i o n i c chain mechanism of von Raven and Heusinger f o r the radiâtion-induced l o s s of u n s a t u r a t i o n i n VB inasmuch as the endr e s u l t i s i n d i s t i n g u i s h a b l e from that of the photochemical analog. The r a t h e r high y i e l d of methyl groups i n the photo-, r a d i a t i o n or thermally-induced c y c l i z a t i o ing hydrogen t r a n s f e r

o c c u r r i n g a t the same time as Reaction 3. F i n a l l y , the c r o s s l i n k i n g encountered i n the UV- or γ-irradiated or t h e r m a l l y - t r e a t e d VB could r e s u l t from i n t e r m o l e c u l a r c y c l o a d d i t i o n of v i n y l double bonds (analogous t o the i n t r a m o l e c u l a r Reaction 3) along with a small c o n t r i b u t i o n from r e a c t i o n s between polymeric r a d i c a l s generated i n Reaction 4. Acknowledgment The authors thank Mrs. Linda K. Yurash f o r experimental assistance.

Literature Cited 1. Von Raven, Α.; Heusinger, H. J. Polym. Sci. Polym. Chem. Ed. 1974, 12, 2255 2. Okamoto, H.; Iwai, T. Kobunshi Ronbonshu, Eng. Ed. 1976, 5, 292. 3. Golub, Μ. Α.; Rosenberg, M. L. J. Polym. Sci. Polym. Chem. Ed. 1980, 18, 2543. 4. Golub, M. A. Rubber Chem. Technol. 1978, 51, 677; and references cited therein. 5. Carbonaro, Α.; Greco, A. Chim. Ind. (Milan) 1966, 48, 363. 6. Golub, M. A. J. Polym. Sci. Polym. Chem. Ed. 1981, 19, 1073. 7. Golub, M. A. J. Phys. Chem. 1965, 69, 2639. 8. Binder, J . L. J. Polym. Sci. 1966, B4, 19. RECEIVED March 1, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

14 C3 Cyclopolymerization: Cationic Cyclopolymerization of 1,3-Bis(p-vinylphenyl)propane and Its Derivatives JUN NISHIMURA and SHINZO YAMASHITA Kyoto Institute of Technology, Department of Chemistry, Faculty of Polytechnic Science, Sakyoku, Kyoto 606, Japan The cyclopolymerizatio (St-C -St), C3 cyclopolymerization, polymerization has the similar behavior to the fluores­ cence emission of 1,3-diphenylpropane and its deriva­ tives (n=3 rule or C3 rule). The monomer and its derivatives were prepared by the convenient method from the corresponding α-phenethylalcohol derivatives, using dimethyl sulfoxide-ZnCl -CCl COOH system. St-C -St gave a cyclopolymer only by cationic initiators, and the presence of cyclized units in the main chain was elucidated by several spectroscopic analyses and also by the isolation of cyclocodimers obtained from the reaction of the monomer with styrene in the presence of the catalytic amount of CF SO H. The cyclopolymerization is revealed to be extreme­ ly sensitive to the structure of the monomer. Among the monomers investigated, St-C -St, 1,4-bis(p-vinylphenyl)butane (St-C -St), 1,3-bis(p-vinylphenyl)butane, 1,3-bis(p-vinylphenyl)-2-methylpropane, and 1,3-bis(4-vinylnaphthyl)propane (VN-C -VN) were cyclopolymerized. 3

2

3

3

3

3

3

4

3

The i n t r a - and i n t e r m o l e c u l a r i n t e r a c t i o n between c a t i o n i c center and π-electron system have a t t r a c t e d many chemists and much knowledge on the i n t e r a c t i o n has been accumulated (1 ) . In 1975, we intended t o apply such a kind o f i n t e r a c t i o n to c y c l o p o l y m e r i z ­ a t i o n . Thus, i t i s expected that the t r a n s i t i o n s t a t e l e a d i n g to a s t r a i n e d c y c l i c u n i t i n the p o l y m e r i z a t i o n could be s t a b i l i z e d by the i n t r a m o l e c u l a r a t t r a c t i v e i n t e r a c t i o n between c a t i o n i c growing-end and π-system: There had been few examples o f c y c l o polymerizations g i v i n g s t r a i n e d u n i t s . A paracyclophane u n i t was employed as a s t r a i n e d c y c l i c u n i t i n the polymer main c h a i n . In Table I are summarized some cyclophanes with t h e i r s t r a i n energies. According t o the c a l c u l a t i o n reported by Boyd ( 4 ) , most of the s t r a i n of [3.3]paracyclophane (I) i s due to the r e p u l s i o n o f 0097-6156/82/0195-0177$06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

178

POLYMERS WITH CHAIN-RING STRUCTURES

Table I Cyclophane

S t r a i n Energies of Some Cyclophanes

S t r a i n Energy kcal/mol(kJ/mol)

Cyclophane

S t r a i n Energy kcal/mol(kJ/mol)

12 (50)

2 (8)

a

See references 2, 3 and 4. given by the present authors.

The values i n parentheses were

the f a c e - t o - f a c e o r i e n t e d π-clouds of benzene r i n g s . When the s t r a i n energy could be reduced o r compensated by the donor-accept­ or i n t e r a c t i o n between two benzene r i n g s , the s t r a i n e d p a r a c y c l o ­ phane u n i t would be r e a d i l y introduced i n the main chain by a polymerization. In f a c t , the t i t l e compound, l,3-bis(£-vinylphenyl)propane (St-C3-St), was polymerized by some c a t i o n i c i n i t i ­ ators t o a f f o r d the polymer c o n t a i n i n g [3.3]paracyclophane u n i t i n the main chain ( 5 ) .

In t h i s paper, we would l i k e to present the r e s u l t s on the c y c l o p o l y m e r i z a t i o n as a review f o c u s i n g on the s t r u c t u r e o f the monomers and t h e i r c y c l o p o l y m e r i z a b i l i t i e s . P r e p a r a t i o n of S t - C - S t 3

and i t s D e r i v a t i v e s

Since monomers used f o r the c y c l o p o l y m e r i z a t i o n are r a t h e r unusual, but a r e considered to have the usage as c r o s s l i n k i n g agents, a b r i e f d i s c u s s i o n o f t h e i r p r e p a r a t i o n seems to be beneficial. In 1963, S t - C - S t and i t s d e r i v a t i v e s were prepared f o r the 3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

14.

NISHIMURA AND

C3 Cyclopolymerization

YAMASHITA

179

f i r s t time by Wiley and Mayberry (6) f o r the study o f t h e i r copolymerizations with s t y r e n e . They used the p y r o l y s i s of a-phenethyla l c o h o l d e r i v a t i v e s over A I 2 O 3 . Recently, Schwachula and Lukas (7) modified the dehydration of α-phenethy1alcohol i n dimethyl s u l f o x i d e (DMSO), which was o r i g i n a l l y discovered by T r a y n e l i s e t a l . (8), and c a r r i e d out the p r e p a r a t i o n of S t - C i - S t i n DMSO i n the presence of a c a t a l y t i c amount of H S0i*. We a l s o independently modified the dehydration i n DMSO with ZnCl -CCl C00H ( 9 ) . 2

2

CH

3

3

CHOH ZnCl 'CCl3COOH

(2)

2

DMSO Our method i s e f f i c i e n t and gives s e v e r a l d i s t y r y l compounds r e l a t e d to St-C3~St i n reasonable y i e l d s . R e s u l t s of the prepara­ t i o n are l i s t e d i n Table I I . These monomers now can be e a s i l y prepared. Table I I P r e p a r a t i o n of Monomers Monomer

Yield

St-Cx-St St-C -St St-C -St St-C^-St St-C -St VN-C3-VN

(%) 52 68 87 88 73 54

2

3

5

Monomer

Yield

43

u

55^ 59

a

Reference 9.

b

L

Unpublished

S t r u c t u r e o f Cyclopolymer

data.

from S t - C - S t or VN-C3-VN 3

I t i s g e n e r a l l y d i f f i c u l t to confirm the presence of c y c l i z e d u n i t i n a polymer. We can see one of the complete, b e a u t i f u l s t r u c t u r a l proofs i n the s t u d i e s of B u t l e r and h i s a s s o c i a t e s (10, 11). Such a k i n d of proof, however, i s not done u s u a l l y . The polymers, which are made of d i v i n y l monomers and s o l u b l e d e s p i t e of low r e s i d u a l u n s a t u r a t i o n , are apt t o be regarded as c y c l o p o l y -

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING STRUCTURES

180

mers. The c r i t e r i o n i s considered to be v a l i d i f the c y c l i c u n i t i s f i v e - or six-membered, and the degree of p o l y m e r i z a t i o n i s high enough. But more evidences other than the s o l u b i l i t y should be necessary when the c y c l i c u n i t has a p e c u l i a r s t r u c t u r e l i k e a cyclophane. The chemistry of cyclophanes has been s t u d i e d e x t e n s i v e l y by Cram and others (12) , and t h e i r f o l l o w i n g s p e c t r o s c o p i c p r o p e r t i e s are r e v e a l e d : C h a r a c t e r i s t i c absorption around 11 μ i n IR s p e c t r o ­ scopy (13), high f i e l d s h i f t of aromatic protons i n *NMR s p e c t r o ­ scopy due t o the s h i e l d i n g e f f e c t of the opposite aromatic nucleus (14), abnormal absorption at c a . 240 nm and r e d - s h i f t e d , broad Bband i n UV spectroscopy (15), r e d - s h i f t e d CT-band with TCNE i n v i s i b l e spectroscopy (VS) (14, 16), and c h a r a c t e r i s t i c p r o p e r t i e s i n f l u o r e s c e n c e spectroscopy (FS) (17, 18) and CNMR spectroscopy (19), which are d i s c u s s e 13

Table I I I S p e c t r a l Data

1

IR (cm" )

919

UV

Absorption a t ca. 240 nm. Characteristic Β-band.

VS (CT-complex with TCNE, nm) 1

NMR (Aromatic protons, 6)

928 Absorption at ca. 240 nm. Characteristic B-band.

904, 988 Minimum a t ca. 240 nm.

599

608

520

6.4

6.5

7.1

P o l y ( S t - C - S t ) obtained by c a t i o n i c i n i t i a t o r s has the same c h a r a c t e r i s t i c s p e c t r o s c o p i c p r o p e r t i e s as [3.3]paracyclophane. The s p e c t r a l data o f the cyclopolymer and the l i n e a r polymer are shown i n Table I I I , F i g u r e s 1 and 2, together with the cyclophane. I t i s known that [3.3]paracyclophane, which has the almost highest transannular i n t e r a c t i o n of the l e s s d i s t o r t e d benzenes (12), has the f l u o r e s c e n c e emission a t longer wavelength (356 nm) (18) than the excimer of 1,3-diphenylpropane (332 nm). The f l u o r e s c e n c e spectrum of the cyclopolymer, p o l y ( S t - C 3 - S t ) , r e c o r d ­ ed under the same c o n d i t i o n s as f o r [3.3]paracyclophane i s i l l u s ­ t r a t e d i n F i g u r e 1 (20). Both have the f l u o r e s c e n c e a t the same wavelength, and t h e r e f o r e the polymer i s supported to c o n t a i n [3.3]paracyclophane u n i t s as sequence u n i t s . The f l u o r e s c e n c e emission a t 312 nm i s a s c r i b e d t o the r e s i d u a l s t y r y l groups. 3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

14.

NiSHiMURA A N D YAMASHiTA

C3 Cyclopolymerization

181 1 3

The s t r u c t u r e of poly(St-C3~St) can be a l s o c l a r i f i e d by C NMR spectroscopy. Although the polymer gave a r a t h e r complicated spectrum, carbons i n the l i n k a g e and a p a r t of aromatic carbons, numbered from 1 to 4 i n the s t r u c t u r e i l l u s t r a t e d i n equation (1), were able to be assigned e a s i l y . The chemical s h i f t s o f these carbons are almost the same as those of [3,3]paracyclophane.

(I) The comparison of the chemica compounds i s shown i n F i g u r and 3 are a f f e c t e d s i g n i f i c a n t l y by the s t r a i n . Recently we i s o l a t e d the cyclodimers shown i n equation (3) , under a c a t i o n i c c o n d i t i o n (21) , so that the s t r u c t u r e of the cyclopolymer, o r the cyclophane-containing polymer i s now f i r m l y established.

Φ

The next i n t e r e s t i n g subject on the s t r u c t u r e would be the e l u c i d a t i o n of the m i c r o s t r u c t u r e of the polymer, u s i n g the s p e c t r o s c o p i c data of model compounds, cyclocodimers and t h e i r derivatives. The s t r u c t u r e of the naphthalenophane-containing cyclopolymer was a l s o c l a r i f i e d i n the same manner as f o r poly(St-C3~St) (22). A l l s p e c t r o s c o p i c r e s u l t s shown i n Table IV are c o n s i s t e n t with the proposed s t r u c t u r e f o r the polymer. Again the recent c y c l o c o d i m e r i z a t i o n f i n a l l y concluded the presence of naphthalenophane u n i t s i n the polymer c l e a r l y (21).

(4)

VN-C3-VN

syn unit

antiunit

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

182

POLYMERS WITH CHAIN-RING

STRUCTURES

CO s eu

>

u

CO

Wavelength, Figure 1.

400

360

320

nm

Fluorescence spectra of the cyclopolymer and linear polymer of bis(pvinylphenyl)propane.

• P(St-C -St) 3

0 (I)

Β Ο*

< -2

-4

Figure 2. Chemical shift differences in the cyclopolymer and linear polymer of bis(p-vinylphenyl)propane. The standard was 1 3-bis(p-isopropylphenyl)propane. t

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

14.

NISHIMURA AND

183

C3 Cyclopolymerization

YAMASHITA

As shown i n Figure 3, poly(VN-C -VN) have a maximum f l u o r e s ­ cence emission at 356 nm due to r e s i d u a l v i n y l n a p h t h y l groups, 3

Table IV

VS FS

(with TCNE, (nm)

nm)

X

HNMR (aromatic protons, δ)

Spectroscopic Data of Poly(VN-C -VN) and Related Compounds 3

80 356 465 8.0 (br 7.3 (br 6.8 (br

m) m)

complex 358 465 7.27 , 7.77 , 7.95 (m,8H)° (m,8H) (m,4H) 6.90 , 5.98 . 7.30 (s,4H) (s,4H)° (m,10H) D

b

m)

a See Figure 3. b Reference 23. c I n c l u d i n g v i n y l protons, and another at 465 nm due to syn-[3.3](l,4)naphthalenophane u n i t , but e x h i b i t e d l i t t l e emissions from the excimer of open-chain d i naphthylpropane u n i t s and anti-[3.3](l,4)naphthalenophane units. T h i s evidence and that from NMR spectroscopy, which showed almost no resonance at 67.77 f o r a n t i u n i t s , c l e a r l y l e d the c o n c l u s i o n that poly(VN-C -VN) contained syn u n i t s predominantly among two p o s s i b l e isomeric c y c l i z e d u n i t s . In c o n c l u s i o n , d i f f e r i n g from polymers having ordinary c y c l i c u n i t s , the s t r u c t u r e of these cyclophane-containing polymers can be e l u c i d a t e d r e a d i l y and f i r m l y by s e v e r a l s p e c t r o s c o p i c methods. 3

S e v e r a l E f f e c t s on the

Cyclopolymerization

Can any k i n d of i n i t i a t o r produce the cyclopolymer from S t - C St? Since the monomer i s a k i n d of styrene d e r i v a t i v e , so i t could be polymerized by a v a r i e t y of i n i t i a t o r s ; c a t i o n i c , r a d i c a l , a n i o n i c , and c o o r d i n a t i o n c a t a l y s t s , and the question could be answered by the r e s u l t s of the p o l y m e r i z a t i o n . When common r i n g s are incorporated i n cyclopolymers as sequence u n i t s , r a d i c a l and c a t i o n i c i n i t i a t o r s are known g e n e r a l ­ l y to give h i g h l y c y c l i z e d polymers (24). However, a n i o n i c i n i t i a t o r s give a l i t t l e or almost no c y c l i z e d u n i t s i n the main 3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

ce

W

Η

§

G η

Figure 3. Fluorescence spectra. (Reproduced, with permission, jrom Ref. 22.)

ο

5

1

ï

S

Ο

H

Jg

m

ce

00

Ο r

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

14.

185

C3 Cyclopolymerization

NISHIMURA AND YAMASHITA

chain. McCormick and B u t l e r suggested that a n i o n i c species must form the unstable 4n7T-system with a double bond i n t r a m o l e c u l a r l y to introduce c y c l i z e d u n i t s i n the main c h a i n , so that the c y c l i z a t i o n does not take p l a c e smoothly (25). We found that r a d i c a l , a n i o n i c , and c o o r d i n a t i o n polymerizat i o n gave benzene-insoluble polymer or s o l u b l e polymer as shown i n Table V (26). These polymers, however, d i d not e x h i b i t the c h a r a c t e r i s t i c s p e c t r a f o r [3.3]paracyclophane u n i t s above mentioned. Therefore they were concluded not to be cyclopolymer. Only c a t i o n i c i n i t i a t o r s could induce c y c l o p o l y m e r i z a t i o n of St-C3~St (27, 28). Before the d i s c u s s i o n on the f a c t that the r a d i c a l i n i t i a t o r s f a i l e d to cyclopolymerize St-C3~St, we need the c l o s e examination of examples f o r the s y n t h e s i s of the [3.3]paracyclophane s k e l e t o n . Because, f o r the synthese paracyclophane, the p r o p e r t i e r e a c t i o n s seem to a f f e c t the c y c l i z a t i o n of open-chain s t a r t i n g materials. Cram and h i s a s s o c i a t e s (15) used the f o l l o w i n g a c y l o i n r e a c t i o n f o r the c y c l i z a t i o n of the s t a r t i n g m a t e r i a l to [3.3]paracyclophane s k e l e t o n , because the r e a c t i o n of the diphenylpropane d e r i v a t i v e (II) gave very l i t t l e amount of the d e s i r e d c y c l i z e d product, even i f the high d i l u t i o n technique was employed.

/- w h e r e ο·ν ι and Sppj a r e t h e molar e n t r o p i e s ( a t 298.16 Κ i n t h e i d e a l gas s t a t e ) o f the h y d r o c a r b o n m o l e c u l e s 2H and PH o b t a i n e d by s a t u r a t i n g w i t h a Κ atom t h e f r e e e l e c t r o n o f Q» and Ρ · r e s p e c t i v e l y , and =CH

105.0-106.0

2

146.0-149.0

0.8-1.0 >^CH

25.0

3

7.0

128.5-131.0

2.25

19.8-20.8

CH.

CH

3

-

5.5

133.0-136.0

119.0 0.03 132.5

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

16.

BALL

• 160

l

ET AL.

I 140

ι

215

1,4-Dimethylenecyclohexane

I 120

ι

ι 100

ι

ι 80

ι

ι Θ0

ι

1 40

1

1 20

1

L 0

Ho(ppm) Figure 4.

1S

20 MHz C-NMR spectra of poly( 1,4-dimethylenecyclohexane), Sampies 13,16, and 22, in CCl solution at room temperature. k

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING STRUCTURES

216

i z a t i o n s proceed best between -30° and -15° suggest that proton transfer-rearrangement processes may be a s i g n i f i c a n t f e a t u r e of c a t i o n i c 1,4-dimethylenecyclohexane p o l y m e r i z a t i o n s . Since double bonds e x o c y c l i c to six-membered r i n g s r e a d i l y rearrange t o endocyc l i c double bonds, i t i s reasonable to expect the f o l l o w i n g t r a n s formations to occur a t the higher p o l y m e r i z a t i o n temperatures:

I Monomers I and V I I might b l a r g e number of d i f f e r e n

VII responsibl

VIII fo

th

incorporatio

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

f

16.

BALL

E T AL.

1,4-Dimethylenecyclohexane

217

The above r e a c t i o n s can e x p l a i n the i n c o r p o r a t i o n of u n i t s with e n d o c y c l i c u n s a t u r a t i o n i n t o the polymers. The h i g h l y hindered e n d o c y c l i c double bonds present i n such s t r u c t u r e s probably have low p o l y m e r i z a t i o n c e i l i n g temperatures and would r e s i s t polymeriz a t i o n . They could be d i f f i c u l t t o brominate o r hydrogenate. I t i s our f a i l u r e t o a p p r e c i a t e the l i m i t e d r e a c t i v i t y o f e n d o c y c l i c double bonds i n s t r u c t u r e s such as IV, IX and X that caused us to overlook them i n our o r i g i n a l i n v e s t i g a t i o n (9) · T h i s l i m i t e d r e a c t i v i t y a l s o e x p l a i n s why s o l u b l e polymers can be formed i n 1,4dimethylenecyclohexane polymerizations even when c y c l o p o l y m e r i z a t i o n does not seem to occur. The r e a c t i o n s depicted above a l s o e x p l a i n the presence of a small amount o f conjugated diene u n i t s present i n the polymers. The methyl groups present on saturated carbon atoms i n the polymers can be explaine e n d o c y c l i c double bonds i probably not reasonable to expect such behavior from s t r u c t u r e s such as I I I , IV, IX or X, f o r reasons already d i s c u s s e d , the f o l lowing r e a c t i o n seems f e a s i b l e :

O x i d a t i o n - r e d u c t i o n processes i n v o l v i n g V I I I or r e l a t e d s t r u c t u r e s and unsaturated s t r u c t u r e s present i n the system ( i n c l u d i n g endoc y c l i c double bonds) are probably an a d d i t i o n a l source of methyl groups on saturated carbon atoms i n the polymers. Such r e a c t i o n s w i l l be d r i v e n by the great tendency of V I I I and r e l a t e d s t r u c t u r e s to aromatize, v i z .

VIII

XI

A l k y l a t i o n of aromatic s t r u c t u r e s formed by t h i s process could be r e s p o n s i b l e f o r the small amount of aromatic r i n g s incorporated i n the polymers.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS

218

WITH CHAIN-RING STRUCTURES

I t thus appears that the p r i n c i p a l s t r u c t u r a l f e a t u r e s found i n poly(1,4-dimethylenecyclohexane) can be explained by conven­ t i o n a l carbonium i o n chemistry. There i s no i n d i c a t i o n that c y c l o ­ p o l y m e r i z a t i o n occurs i n these p o l y m e r i z a t i o n s and there i s much evidence to i n d i c a t e that the double bonds present i n t h i s diene r e a c t independently. Some of them are i n v o l v e d i n p o l y m e r i z a t i o n r e a c t i o n s , but a l a r g e p r o p o r t i o n isomerize to r e l a t i v e l y s t a b l e e n d o c y c l i c double bonds. Under p o l y m e r i z a t i o n c o n d i t i o n s where i s o m e r i z a t i o n i s f a v o r a b l e , s o l u b l e , unsaturated polymers having complex s t r u c t u r e s are obtained. When i s o m e r i z a t i o n r e a c t i o n s are not f a v o r a b l e (low temperatures, use of Z i e g l e r - N a t t a c a t a l y s t s ) , the double bonds polymerize independently and c r o s s l i n k e d products are obtained. Experimental 1,4-dimethylenecyclohexane - A mixture of potassium metal (59.6g., 1.57 mole) and t-butanol (1-1.) was s t i r r e d under r e f l u x i n a n i t r o g e n atmosphere f o r 2 h r s . To the r e s u l t i n g s o l u t i o n of potassium t-butoxide i n t-butanol was added trans-1,4-di(iodomethyl)-cyclohexane (28) (182g., 0.5 mole). The mixture was r e f l u x ed and s t i r r e d under n i t r o g e n f o r 24 h r s . The mixture was t r e a t e d with 2400 ml water and the organic l a y e r which separated was wash­ ed 4 times with 200 ml p o r t i o n s of water, f i l t e r e d and d r i e d over anhydrous MgSOi*. The l i q u i d was then d i s t i l l e d under reduced pressure to o b t a i n 28.8g. (53% y i e l d ) 1,4-dimethylenecyclohexane, b.p. 54-55° (75 mm), n * 1.4688, d * 0.8133. Anal. - Calc'd f o r C H (108.2): C, 88.82; H, 11.18, Bromi n a t i o n Eq. Wt. 54.1. Found: C, 88.86, H, 11.27, Bromination Eq. Wt. 53.6. The diene q u i c k l y absorbed 1.96 moles of hydrogen when hy­ dro genated at room temperature u s i n g platinum as a c a t a l y s t . O z o n o l y s i s of the diene i n dry pentane a t -20°, f o l l o w e d by t r e a t ­ ment of the r e a c t i o n mixture with a d i l u t e s o l u t i o n of dimedon provided a 56 percent y i e l d of the dimedon d e r i v a t i v e of formalde­ hyde, m.p. 188.5-190° The H-NMR spectrum of the diene c o n s i s t e d of two sharp s i n ­ g l e t s a t 2.09 (-CH -) and 4.66 (=CH ) ppm having r e l a t i v e i n t e n s i ­ t i e s of 2:1. The diene absorbed only weakly i n the u l t r a v i o l e t r e g i o n at 262 nm (ε=11.0) and at 234 nm (ε=14.7). In the presence of i o d i n e , i t absorbed at 298 nm (ε'=47.7). T h i s i s i n goodagreement with r e s u l t s expected f o r 1,4-dimethylenecyclohexane based on data reported by Long and Neuzil.(29) B u t l e r and Van Heiningen have a l s o i n v e s t i g a t e d the uv a b s o r p t i o n of t h i s monomer ( 8 ) . 5

2 5

D

8

1 2

1

2

2

P o l y m e r i z a t i o n of 1,4-Dimethylenecyclohexane w i t h B F - A 100 ml two-neck f l a s k was r i n s e d with d i l u t e NH3 s o l u t i o n and d r i e d i n a i r at 150°C. While s t i l l hot, the f l a s k was f l u s h e d with n i t r o g e n and one of the necks was equipped with a rubber gum 3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

16.

BALL

219

1,4-Dimethylenecyclohexane

ET AL.

s e a l . A f t e r the f l a s k had cooled under N to room temperature, 1,4-dimethylenecyclohexane (6.7 g., 0.062 mole) and methylene c h l o r i d e (42 ml) were added by s y r i n g e . While maintained under n i t r o g e n , the mixture was s t i r r e d m a g n e t i c a l l y and cooled by immer­ s i o n i n a bromobenzene - Dry Ice bath a t -30°C f o r one-half hour. Boron t r i f l u o r i d e was then introduced very slowly i n t o the n i t r o ­ gen stream flowing over the r e a c t i o n mixture u n t i l a red-orange c o l o r developed i n the mixture. The mixture was maintained under n i t r o g e n and s t i r r e d a t -30°C f o r 3 hours. T r i e t h y l a m i n e (1 ml) was then i n j e c t e d i n t o the mixture and the c o l o r disappeared. The mixture was f i l t e r e d through a coarse g l a s s f r i t i n t o 500 ml o f acetone. The polymer which coagulated was f i l t e r e d and d r i e d t o g i v e a f i n e l y d i v i d e d white s o l i d (3.75 g., 55%). The polymer was f u r t h e r p u r i f i e d by d i s s o l v i n g i t i n hot methylene c h l o r i d e , f i l ­ t e r i n g the s o l u t i o n throug the f i l t r a t e to 500 ml o c o l l e c t e d and d r i e d i n a vacuum d e s s i c a t o r . The i n t r i n s i c v i s c o s ­ i t y o f the polymer i n benzene a t 30°C was 0.079. The molecular weight, determined c r y o s c o p i c a l l y i n benzene, was 8,400. A n a l . C a l c d f o r ( C H i ) : C, 88.82; H, 11.18. Found: C, 88.72; 88.67; H, 11.28; 11.12; Bromination E q u i v a l e n t Wt., 5,200, 6,000; Grams of polymer absorbing one mole of hydrogen, 7,400, 8,200. The polymer was a white powdery s o l i d . I t was s o l u b l e i n most o r g a n i c s o l v e n t s i n c l u d i n g pentane, hexane, benzene, toluene, xylene, methylene c h l o r i d e , chloroform and carbon t e t r a c h l o r i d e . I t was i n s o l u b l e i n acetone, methanol and water. The m a t e r i a l softened and became f l u i d between 170-180°C, showing only s l i g h t discoloration. The polymer showed strong methylene a b s o r p t i o n a t 2900, 2840 and 1450 cm" i n the i n f r a r e d r e g i o n . In a d d i t i o n , weak absorp­ t i o n s a t 1640 and 888 cm" i n d i c a t e d the presence of a few t e r m i n a l o l e f i n i c l i n k a g e s . A b s o r p t i o n a t 1380 cm- i n d i c a t e d the presence of methyl groups. The u l t r a v i o l e t spectrum o f the polymer, measured i n c y c l o hexane s o l u t i o n , was e s s e n t i a l l y the same i n the presence o r ab­ sence of i o d i n e . The polymer showed only weak a b s o r p t i o n i n CH Cl2 s o l u t i o n , having a maximum o f 258 nm (ε=340/monomer u n i t o r 27,000/polymer molecule). A f t e r treatment w i t h a d i l u t e s o l u t i o n of c h l o r i n e i n CCli», the polymer no longer showed an a b s o r p t i o n maxima a t 258 nm; i n s t e a d , t a i l a b s o r p t i o n of an i n t e n s e band whose maximum would occur below 210 nm was observed. P o l y m e r i z a t i o n s conducted u s i n g other c a t a l y s t s , tempera­ t u r e s , s o l v e n t s , and monomer c o n c e n t r a t i o n s were conducted accord­ ing t o the procedure d i s c u s s e d above. The r e s u l t s are summarized i n Table I . NMR Measurements - ^•H- and C - NMR s p e c t r a of the polymers i n C D C I 3 s o l u t i o n a t ambient temperature were recorded a t 300 and 20 MHz, r e s p e c t i v e l y , u s i n g V a r i a n HR-300 (CW mode) and CFT-20 (FT mode) spectrometers. The C-NMR s p e c t r a were the r e ­ s u l t of over 100 Κ accumulations u s i n g a p u l s e width o f 10y sec. T e t r a m e t h y l s i l a n e was used as an i n t e r n a l standard. 2

f

8

2

1

1

1

2

1 3

13

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

220

POLYMERS WITH CHAIN-RING STRUCTURES

Acknowledgemen t We a r e pleased t o acknowledge that the p a r t i c i p a t i o n o f one of us i n t h i s study was made p o s s i b l e by a grant from the Yugoslavian Academy of Sciences.

Literature Cited 1. Butler, G.B. J. Polym. Sci., Polymer Symposium 1978, 64, 71. 2. Corfield, C.G. Chem. Soc. Rev. 1972, 1(4), 523. 3. McCormick, C.L.; Butler, G.B. J. Macromol. Sci., Rev. Macromol. Chem. 1972, C8, 201. 4. Corfield, C.G.; Aso , C.; Butler, G.B. "Progress in Polymer Science"; A.D. Jenkins, Ed.; Pergamon Press; Oxford, 1975, Vol. 4, pp 71-207. 5. Butler, G.B.; Miles 723. 6. Butler, G.B.; Miles, M.L. J. Polymer Sci. 1965, 3A, 1609. 7. Frazer, A.H.; O'Neill, W.P. J. Am. Chem. Soc. 1963, 85, 2613. 8. Butler, G.B.; Van Heiningen, J.J. J. Macromol. Sci. 1974, A8, 1139, 1175. 9. Ball, L.E.; Harwood, H.J. Am. Chem. Soc., Div. Polym. Chem., Preprints 1961, 2(1), 59. 10. Ball, L.E. Ph.D. Dissertation, University of Akron 1961; Dissertation Abstr. 1961, 22, 1404; Chem. Abstr. 1962, 56, 5846 h. 11. Shannon, F.D. Ph.D. Dissertation, University of Akron 1964; Dissertation Abstr. 1965, 25, 3849; Chem. Abstr. 1965, 62, 13249c. 12. Sebenik, A; Harwood, H.J. Amer. Chem. Soc., Div. Polym. Chem., Preprints 1981, 22, 15. 13. Lautenschlaeger, F.; Wright, G.F. Can. J. Chem. 1963, 41, 1972. 14. Fr. Patent 1,323,328 (April 5, 1963); Chem. Abstr. 1963, 59, 9784. 15. St-Jacques, M.; Bernard, M. Can. J. Chem. 1969,47,2911. 16. Acker, D.S.; Blomstrom, D.C. U.S. Patent 3,115,506 (Dec. 24, 1963); Chem. Abstr. 1964, 60, 14647d. 17. Wiberg, K.B.; Epling, G.A.; Jason, M. J. Am. Chem. Soc. 1974, 96, 912. 18. Wiberg, K.B.; Burgmaier, G.J. J. Am. Chem. Soc. 1972, 94, 7396. 19. Buchta, E.; Kröniger, A. Chimia 1969, 23, 225. 20. Spainhour, J.D. U.S. Patent 3,331,819 (July 18, 1967); Chem. Abstr. 1967, 67, 74012k. 21. Denkowski, G.S. M.S. Dissertation, University of Akron 1965. 22. Marshall, J.L.; Miller, D.E., Org. Magn. Reson. 1974, 6, 395.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

16.

BALL

ET

AL.

1,4-Dimethylenecyclohexane

221

23. Stothers, J.B. "Carbon-13 NMR Spectroscopy, Academic Press, New York, N.Y., 1972, 24. Johnson, L.F.; Jankowski, W.C., "Carbon-13 NMR Spectra", Wiley-Interscience, New York, 1972. 25. Pouchert, C.Y.; Campbell, J.R., "The Aldrich Library of NMR Spectra", Aldrich Chemical Co., Inc., Milwaukee, Wisconsin, 1974. 26. Olah, G.Α.; and White, A.M. J. Am. Chem. Soc. 1969, 91, 3954. 27. Lippmaa, E.; Pehk, T.; Paasivirta, J.; Belikova, N.; Plate, A. Org. Magn. Reson. 1970, 2, 581. 28. Haggis, G.H.; Owen, L.N. J. Chem. Soc. 1953, 404. 29. Long, R.D.; Neuzil, R.W. Anal. Chem. 1955, 27, 1110. RECEIVED February 1, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

17 Acetylene-Terminated Fluorocarbon Ether Bibenzoxazole Oligomers ROBERT C. ΕVERS and GEORGE J. MOORE Air Force Wright Aeronautical Laboratories, Materials Laboratory, Wright-Patterson Air Force Base, OH 45433 JERALD L. BURKETT University of Dayton Research Institute, Dayton, OH 45469 Acetylene terminated fluorocarbon ether bibenzo­ xazole (FEB) oligomers were prepared by the poly­ cyclocondensatio esters with fluorocarbo monomers followed by subsequent reaction with a new endcapping agent, 2-amino-4-ethynylphenol. The average number of repeat units in the oligomers was controlled by the stoichiometry of the oligomeri­ zation reaction. Oligomer structure was verified by elemental and infrared spectral analyses. Onset of curing of the acetylene terminated FEB oligomers, as determined by differential scanning calorimetry, occurred in the 180-200°C range with reaction maxima being reached above 280°C. The resultant cured oligomers exhibited glass transi­ tion temperatures as low as -55°C. No crystalline melt temperatures were observed. Onset of break­ down of the reddish, transparent rubbers during thermogravimetric analysis in an air atmosphere took place in the 375-400°C range; complete weight loss occurred at approximately 600°C. Thermooxidatively s t a b l e fluorocarbon ether bibenzoxazole (FEB) polymers with g l a s s t r a n s i t i o n temperatures (Tg) as low as -58°C can be synthesized through the a c e t i c acid-promoted p o l y cyclocondensation of f l u o r o c a r b o n ether d i i m i d a t e or - d i t h i o i m i date e s t e r s with f l u o r o c a r b o n ether bis(o-aminophenol) monomers. (1) By j u d i c i o u s m o d i f i c a t i o n of polymer s t r u c t u r e , greater h y d r o l y t i c s t a b i l i t y and more ready c u r a b i l i t y can be achieved.(2) The l a t t e r property i s e f f e c t e d through i n c o r p o r a t i o n i n t o the polymer backbone of hydrocarbon cure s i t e s r e a c t i v e to r a d i c a l induced cure r e a c t i o n s . The present a r t i c l e d e s c r i b e s the s y n t h e s i s o f acetylene terminated FEB oligomers that can be cured by thermal r e a c t i o n s of acetylene end groups. These oligomers can be prepared as shown i n Scheme I by polycyclocondensation of

0097-6156/ 82/0195-0223$06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING

224

STRUCTURES

f l u o r o c a r b o n ether d i i m i d a t e e s t e r s w i t h fluorocarbon ether bis(o-aminophenol) monomers followed by endcapping w i t h an endcapping agent, 2-amino-4-ethynylphenol. The average number of repeat u n i t s , n, i s c o n t r o l l e d by the stoichiometry of the reac­ tion.

+

n=0, 1, 2 R =CF (OCF2CF ) O(CF )50(CF2CF20)y C F f

2

2

x

2

Rf=(CF ) 0 ( C F ) Ο ( C F ) 2

2

2

5

2

2

x+ y=5, 6

2

Scheme I Synthesis of these oligomers and the r e q u i s i t e endcapping agent i s given below. Oligomer c h a r a c t e r i z a t i o n and p r e l i m i n a r y cure s t u d i e s are a l s o d e s c r i b e d . R e s u l t s and D i s c u s s i o n Synthesis o f Endcapping Agent. 2-Amino-4-ethynylphenol was prepared as shown i n Scheme I I . 3-Nitro-4-hydroxyacetophenone was t r e a t e d w i t h a c e t i c anhydride to p r o t e c t the phenolic group. The key r e a c t i o n i n the s y n t h e t i c sequence e n t a i l e d treatment of the acetate e s t e r w i t h a V i l s m e i e r reagent generated from phosphorous o x y c h l o r i d e and Ν,Ν-dimethylformamide. 4-Acetoxy-3-nitro-3chlorocinnamaldehyde was obtained i n 43% y i e l d . Subsequent t r e a t ­ ment o f the aldehyde with sodium hydroxide s o l u t i o n gave 4e t h y n y l - 2 - n i t r o p h e n o l . A l t e r n a t i v e l y , t h i s r e a c t i o n scheme could be c a r r i e d out w i t h a p - t o s y l group p r o t e c t i n g the phenolic f u n c t i o n . However, both formation o f the t o s y l a t e e s t e r and subsequent regeneration of the f r e e phenol were more d i f f i c u l t . A f t e r formation o f the acetylene group, the n i t r o group was s e l e c t i v e l y reduced w i t h sodium d i t h i o n i t e i n an a l k a l i n e medium to y i e l d the d e s i r e d 2-amino-4-ethynyl-phenol. Since t h i s com-

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

17.

Fluorocarbon Ether Bibenzoxazole Oligomers

E VERS ET A L .

225

pound was somewhat s e n s i t i v e to both heat and l i g h t , i t was stored i n the c o l d s h i e l d e d from l i g h t .

OR N0

OR

φ

2

c=o

N 0

2

c-ci

I

CHo

II CH CHO

I

ft R=-CCH

OH

2

φτ™ -—φ-"

3

III

c III c

I

H

C

c

0 2

I

Η Scheme I I

An a l t e r n a t e synthesis as shown i n Scheme I I I of the i n t e r ­ mediate 4-ethynyl-2-nitrophenol was b r i e f l y i n v e s t i g a t e d . The OH

OH N0

2

c H3C-C-OH

I

CH

y ο·

OH

φτ

OH

1

NH

2


105°C (vigorous decomposition). Anal. Calcd f o r CgHyNO: C, 72.14; H, 5.33; N, 10.51; mol. wt., 133. Found: C, 72.47; H, 5.66; N, 9.95; mol. wt., 133 (mass spectrum). 11

8

5

8

4-Ethynyl-2-nitrophenol (Attempted A l t e r n a t e S y n t h e s i s ) . To a s t i r r e d s o l u t i o n of 4-iodo-2-nitrophenol (14.Og, 0.053 mole)(7) i n 150 ml o f t e t r a c h l o r o e t h y l e n e was added b i s ( t r i p h e n y l p h o s p h i n e ) palladium d i c h l o r i d e (0.74g, 0.001 mole), cuprous i o d i d e (0.40g, 0.002 mole), t r i p h e n y l phosphine (0.03g, 0.001 mole), and 50 ml of dry t r i e t h y l a m i n e . A f t e r the r e a c t a n t s were thoroughly mixed, 2-methyl-3-butyn-2-ol (5.4g, 0.064 mole) was added. The s t i r r e d r e a c t i o n mixture was heated slowly to 70-75°C and maintained a t that temperature f o r 16 hours. The t e t r a c h l o r o e t h y l e n e and t r i e t h y l a m i n e were removed under reduced pressure and the red guml i k e r e s i d u e was e x t r a c t e d with hot heptane. The heptane s o l u t i o n was treated with charcoal and the heptane was s t r i p p e d o f f to g i v e a y e l l o w s o l i d (9.5g). The s o l i d was d i s s o l v e d i n benzene and was placed i n a s i l i c a g e l column. E l u t i o n with 1:1 benzene/hexane y i e l d e d 1.8g o f product. The remainder o f the product was removed

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

234

POLYMERS

WITH CHAIN-RING STRUCTURES

by e l u t i o n with 1:1 methylene chloride/hexane. R e c r y s t a l l i z a t i o n from hexane gave 5.0g (41%) of the yellow butynol adduct mp 8082°C. N 0

:

C

5 9

7 2

H

5

0 1

N

6

3 3

m o 1

A n a l . Calcd f o r C H 4 > · » > · 5 > · » * wt., 221. Found: C, 59.61; H, 5.04; Ν, 6.27; mol. wt., 221 (mass spectrum). The butynol adduct (l.Og, 0.005 mole) was d i s s o l v e d i n 200 ml of dry toluene. Potassium hydroxide (0.5g, 0.009 mole) was added and the s t i r r e d r e a c t i o n mixture was r e f l u x e d under n i t r o g e n f o r e i g h t hours. The toluene was g r a d u a l l y d i s t i l l e d over to remove any acetone which r e s u l t e d from cleavage of the butynol adduct. The volume of the r e a c t i o n mixture was kept constant by the a d d i ­ t i o n of f r e s h toluene. The r e a c t i o n mixture was f i l t e r e d and the toluene removed under reduced pressure to g i v e 0.90g of yellow s o l i d , mp 65-70°C. I n f r a r e t h i n l a y e r chromatograph starting material. The butynol adduct (l.Og, 0.005 mole) was d i s s o l v e d i n a b a s i c s o l u t i o n of potassium hydroxide (0.5g, 0.009 mole) i n 200 ml of d i s t i l l e d water. With the volume being kept constant, the orange s o l u t i o n was slowly d i s t i l l e d under n i t r o g e n f o r ten hours to remove any acetone which was formed. The cooled r e d d i s h s o l u t i o n was made a c i d i c by the a d d i t i o n of d i l u t e s u l f u r i c a c i d to give 0.80g of gummy yellow m a t e r i a l . R e c r y s t a l l i z a t i o n from hexane gave 0.50g of almost pure s t a r t i n g m a t e r i a l , mp 79-81°C. n

1 0

Acetylene Terminated FEB Oligomer ( T r i a l No. 4 ) . The f l u o r o ­ carbon ether d i i m i d a t e e s t e r (3.586g, 0.0030 mole) and g l a c i a l a c e t i c a c i d (0.380g, 0.0063 mole) were d i s s o l v e d i n a mixture of 60 ml of Freon 113 and 45 ml of methylene c h l o r i d e a t 45 C. To t h i s c l e a r s o l u t i o n was added the f l u o r o c a r b o n ether bis(o-amino­ phenol) (1.048g, 0.0015 mole) i n four potions over the course of an hour. A f t e r the r e a c t i o n mixture was s t i r r e d under n i t r o g e n a t 40°C f o r 22 hours, 2-amino-4-ethynylphenol (0.445g, 0.0033 mole) and a d d i t i o n a l g l a c i a l a c e t i c a c i d (0.380g, 0.0063 mole) i n 15 ml of methylene c h l o r i d e were added to the c l e a r , p a l e yellow s o l u ­ t i o n . The r e a c t i o n was continued f o r an a d d i t i o n a l 20 hours a t which time the c l e a r r e a c t i o n mixture was t r a n s f e r r e d to a separat o r y f u n n e l . I t was washed s u c c e s s i v e l y with water, d i l u t e sodium bicarbonate s o l u t i o n , and again with water. The o r g a n i c l a y e r was then d r i e d over anhydrous magnesium s u l f a t e , t r e a t e d with char­ c o a l , and reduced i n volume to approximately 15 ml. The c l e a r concentrated s o l u t i o n was t r a n s f e r r e d to a v i a l and the remaining organic s o l v e n t s were c a r e f u l l y removed a t 58°C and 0.01 mm Hg to y i e l d 4.36g (86%) of v i s c o u s , p a l e yellow oligomer. A n a l . Calcd f o r C H 4 N F 0 2 : C, 30.05; H, 0.44; N, 1.77. Found: C, 30.20; H, 0.10; N, 1.68. 7 9

1

4

9 4

2

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

17.

EVERS

E T AL.

Fluorocarbon Ether Bibenzoxazole Oligomers

235

Acknowledgement The authors thank Mrs. Paula Beck f o r a s s i s t a n c e i n the s y n t h e s i s work. The DSC and thermooxidative s t a b i l i t y data were c o n t r i b u t e d by Mr. E. J . S o l o s k i and Dr. G. F. L. E h l e r s .

Literature Cited 1. Evers, R. C., J. Polym. Sci., Polym. Chem. Ed., 1978, 16, 2833. 2. Evers, R. C.; Abraham, T., Am. Chem. Soc., Prepr. Polym. Div., 1979, 20(1), 478. 3. Sobourin, E. T., Am. Chem. Soc., Prepr. Petr. Div., 1979, 24(1), 233. 4. Bellamy, L. J., "The Infrared Spectra of Complex Molecules;" Second Edition, Wiley:Ne 5. Evers, R. C., J. Polym , Polym , , , 2815. 6. Pope, Frank G., Proc. Chem. Soc., 1912, 28, 2933; Chem. Abstr. 1912, 7, 2933. 7. Keimatsu, S., J. Pharm. Soc. Japan, 1924, 507, 319; Chem. Abstr., 1924, 18, 2503. RECEIVED April 28, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

18 Initiation of an Acetylene-Terminated Phenyl Quinoxaline M. A. LUCARELLI, W. B. JONES, JR., L. G. PICKLESIMER, and T. E. HELMINIAK Air Force Wright Aeronautical Laboratories, Materials Laboratory, Wright-Patterson Air Force Base, OH 45433 A series of heterogeneous mixtures was made by adding various amounts of bis(triphenyl phosphine) nickel II chloride, as an initiator phenylquinoxaline g the Differential Scanning Calorimeter (DSC) and the shifts in the exothermic reaction with temperature were associated with the initiator concentrations. From these data, the initiator concentration of 1.0%, by weight, was selected for further investigation. Control samples of the polymer sans initiator were also carried through the investigation. Heats of reaction were measured for these materials in both air and nitrogen atmospheres. Specimens were then interrupted at various stages of cure at 177°C (350°F). Subsequently, these specimens were placed in the DSC and the residual exotherms were measured. The data were interpreted in terms of the extent of cure and used in conjunction with Kinetic theory to estimate the maximum amount of cure that could be expected at 177°C (350°F). The methods and results are discussed herein. A f a m i l y of acetylene-terminated phenyl q u i n o x a l i n e s have been s y n t h e s i z e d by the Polymer Branch o f the M a t e r i a l s Laborat o r y . (1) These phenyl q u i n o x a l i n e s a r e remarkable f o r t h e i r thermooxidative s t a b i l i t y and r e s i s t a n c e to moisture. These m a t e r i a l s have p o t e n t i a l f o r s t r u c t u r a l a p p l i c a t i o n s as adhesives or composite matrix r e s i n s . ( 2 ) The f e a t u r e of moisture r e s i s t a n c e makes the m a t e r i a l s e s p e c i a l l y a t t r a c t i v e f o r bonding aluminum. However, problems a r i s e from the f a c t that a i r c r a f t aluminum a l l o y s (and t h e i r s u r f g c e oxides) a r e a l t e r e d by exposures t o temperatures above 177 C (350 F) and t h i s i s much lower than the p o l y m e r i z a t i o n temperatures of the acetylene-terminated oligomers.

This chapter not subject to U.S. copyright. Published, 1982, American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

238

POLYMERS WITH CHAIN-RING STRUCTURES

In order to overcome t h i s problem, i t was decided to s e l e c t one of the phenylquinoxalines and i n v e s t i g a t e the f e a s i b i l i t y of i n i t i a t i n g the cure r e a c t i o n s a t 177°C (350°F). P h y s i c a l and mechanical c h a r a c t e r i s t i c s have been measured and catalogued f o r the phenyl q u i n o x a l i n e f a m i l y i n a r e l a t e d i n t e r n a l r e s e a r c h p r o j e c t . From these data, 3,3'-Bis(4-[3-ethynyl phenoxy] phenyl)-2,2 -diphenyl-6,6 b i q u i n o x a l i n e (or BA-DAB-BA f o r short) was s e l e c t e d . B i s - ( t r i p h e n y l phosphine) n i c k e l I I c h l o r i d e was chosen as the i n i t i a t o r . f

f

Sample P r e p a r a t i o n Method Although i t i s d e s i r a b l e to have a homogeneous blend of i n i t i a t o r and polymer, a p r a c t i c a l method f o r o b t a i n i n g t h i s i s not known. S e v e r a l method the peak r e a c t i o n temperatur u s i n g the DSC) was s e l e c t e d . I n i t i a l l y , a small sample of the i n i t i a t o r and polymer, both powders a t room temperature, were ground together with mortar and p e s t l e . The blend was t e s t e d i n the DSC. T r y i n g another method, the i n i t i a t o r was d i s s o l v e d i n methanol and allowed to p r e c i p i t a t e on to the polymer (nonsoluble) as the methanol evaporated. The DSC scans showed a s i g n i f i c a n t l y greater r e d u c t i o n i n the exotherm peak temperature. A t h i r d method was t r i e d that gave u n d e s i r a b l e r e s u l t s . The i n i t i a t o r and monomer were d i s s o l v e d i n t e t r a h y d r o f u r a n , a common s o l v e n t . In attempting to s t r i p o f f the THF i n a roto-vac a t room temperature, i t was found that p o l y m e r i z a t i o n of the BA-DABBA was i n i t i a t e d and advanced, even w h i l e there was s t i l l r e t a i n e d s o l v e n t . Since these f a c t o r s c o n t r i b u t e t o p r o c e s s i n g d i f f i c u l t i e s and u n d e s i r a b l e p o r o s i t y i n cured specimens, t h i s method was d i s c a r d e d , and the methanol p r e c i p i t a t i o n method was s e l e c t e d . Influence of I n i t i a t o r Concentration A d i l u t e s o l u t i o n was prepared by d i s s o l v i n g one gram of i n i t i a t o r i n 100ml of methanol. The s o l u t i o n was then p r e c i p i t a ted on to weighed amounts of BA-DAB-BA so that the f i n a l concent r a t i o n s were 0.01, 0.05, 0.10, 0.25, 0.5, 1.00, 2.40, 5.0, and 7.50% by weight. S u f f i c i e n t methanol was added i n order t o wet the BA-DAB-BA. The mixture was mechanically s t i r r e d w h i l e the methanol was allowed to evaporate. Once the mixture was d r y i n a i r i t was h e l d under vacuum overnight to remove any r e s i d u a l methanol. The s o l i d mixtures were then scanned i n the DSC from 20 to 400 C a t a r a t e of 20°C/minute. The exotherm onset and peak temperatures were noted and a r e shown i n Table I . A l s o , i n d i c a t e d i n Table I i s the e f f e c t o f p a r t i c l e s i z e i n the heterogeneous blend. From these data, the i n i t i a t o r c o n c e n t r a t i o n of 1% was selected for further investigation.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

18.

LUCARELLI E T A L .

Acetylene-Terminated Phenyl Quinoxaline

Table I . Exotherm Peak Temperature as a Function o f P a r t i c l e S i z e

MESH

SIZE

GROUND BADABBA

Tp°C

PRECIPITATED BADABBA

Tp°C

9

175

35

500tf

1

242.5

60

250μ

2

203

10

182

80

1770

3

210

11

162

120

125ft

4

200

12

180

200

740

5

175

13

180

250

580

6

-

14

200

325

44(1

7

145

15

230

8

198

16

175

>325

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

239

POLYMERS WITH CHAIN-RING

240

STRUCTURES

Curing Studies Approximately 60 grams of BA-DAB-BA was synthesized u s i n g the Hedberg procedure. (1) One-half of t h i s m a t e r i a l was evaluated i n i t s pure form, w h i l e the other h a l f was f i r s t blended to 1% concen­ t r a t i o n w i t h the i n i t i a t o r u s i n g the methanol p r e c i p i t a t i o n method, and then evaluated. Both samples were subjected t o DSC scans a t 20°C/min. The r e s u l t s are shown i n F i g u r e 1. Rheology The v i s c o s i t i e s of pure and i n i t i a t e d BA-DAB-BA samples were measured d u r i n g 175 C exposure. gSpec^mens were prepared by p r e s s ­ i n g the uncured powder a t 2 χ 10 n/m (40,000 p s i ) i n t o 12mm d i a χ 2mm t h i c k p e l l e t s . Th p e l l e t s were placed betwee Rheometrics RMS-7200 Mechanical Spectrometer and subjected to low frequency ( S i n u s o i d a l Shearing) v i s c o s i t y measurements. The r e s u l t s , shown i n F i g u r e 2, c l e a r l y show the i n i t i a t i n g i n f l u e n c e ofgthe n i c k e l compound. Since p l a t e s l i p p a g e was experienced above 10 p o i s e , an a l t e r n a t e method was used t o evaluate the l a t t e r stages of cure. R e s i d u a l Exotherm The r e a c t i o n exotherms were used t o i n d i c a t e the degree o f cure f o r the polymer samples. The areas under the DSC curves (see F i g 1 ) , between 20 and 350°C, were measured and taken to be the t o t a l heats of r e a c t i o n . A d d i t i o n a l specimens were prepared and placed i n an a i r oven a t 177 C (350°F). P e r i o d i c a l l y , s p e c i ­ mens were withdrawn frgm the oven, placed i n the DSC and scanned from 20 to 350 C a t 20 C/min; and the r e s i d u a l exotherms were measured. These t e s t s were repeated i n a n i t r o g e n environment. The r e s u l t s of the DSC scans a r e i n d i c a t e d i n F i g u r e 3. From the DSC scans, the percent of r e a c t i o n that had occurred was determined from the f o l l o w i n g equation: R = (AHj, - ΔΗ)

where AIL, - T o t a l Heat of Reaction; 92.63 cal/gm BA-DAB-BA and 66.18 cal/gm f o r BA-DAB-BA + i n i t i a t o r . ΔΗ - Area under DSC curve a f t e r χ h r s a t 177°C. P l o t t i n g l o g R versus 1/time (see F i g 4) and e x t r a p o l a t i n g the curve to i n t e r s e c t the o r d i n a t e , i n d i c a t e s the a i r cured samples would approach 89% cure completion f o r pure BA-DAB-BA and 92% f o r the i n i t i a t e d BA-DAB-BA. The data i n d i c a t e both m a t e r i a l s would approach 95% cure completion i n a n i t r o g e n atmosphere.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

18.

LUCARELLi E T A L .

T

Acetylene-Terminated Phenyl Quinoxaline

p

= 225°C

1% I n i t i a t o r

T

i

= 275°C

p

/\ \

241

Neat

0

t 0

i

l

l

100

1 200

.1..

1

1

300

400

Temperature (°C) Figure 1.

Differential scanning calorimetry for BA-DAB-BA DAB-ΒΑ (with 1% initiator).

10

Figure 2.

20

30 40 50 TME (MtfJUTES)

60

(neat) and Β A

70

Viscosity for BA-DAB-BA (neat) and BA-DAB-BA at 175°C isotherm.

(with 1 % initiator)

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

242

POLYMERS WITH CHAIN-RING STRUCTURES

100 90 80

_

i% MrruTON

icted

70 60

1

50

MAT

* 40 30 0

J 0.5

—

L

1 1 1 1 1 1 1 1 |S 1.0 1-5 20 1/ΠΜΕ (HOURS' ) 1

Figure 3. Percent reaction vs. time for BA-DAB-BA (neat) and (with 1 % initiator) at 177°C, isothermal air cure.

BA-DAB-BA

100 90 80 1% MATOft

70

I

60 50 40 30 0

0.5

1.0 1/TME (HOURS' )

1.5

2.0

1

Figure 4. Percent reaction vs. time for BA-DAB-BA (neat) and BA-DAB-BA (with 1% initiator) at 177°C, isothermal nitrogen cure.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

18.

LUCARELLi E T A L .

Acetylene-Terminated Phenyl Quinoxaline

243

D i s c u s s i o n of R e s u l t s Progress has been made i n i n i t i a t i n g the p o l y m e r i z a t i o n r e a c t i o n o f an a c e t y l e n e terminated phenyl q u i n o x a l i n e a t lower temperatures. While t h i s r e s u l t i n i t s e l f i s of p r a c t i c a l s i g n i f i c a n c e t o the A i r Force, the i n v e s t i g a t i o n was embellished t o provide g e n e r i c foundations f o r subsequent s t u d i e s . Observations were a l s o made that may be of i n t e r e s t t o other i n v e s t i g a t o r s . These are as f o l l o w s : (a) At low c o n c e n t r a t i o n s ( l e s s than 1%), i n c r e a s i n g amounts o f i n i t i a t o r p r o g r e s s i v e l y lower both the onset and peak exotherm temperatures (as measured u s i n g the DSC); (b) Above 1%, the DSC curve begins t o s p l i t i n t o two peaks, probably a c h e m i c a l l y i n i t i a t e d peak and the normal thermally i n i t i a t e d peak; (c) High i n i t i a t o r c o n c e n t r a t i o n s a r e not necessary or e f f e c t i v e s i n c e uncured BA-DAB-B at about 110 C and p o l y m e r i z a t i o l i n e o r g l a s s y s t a t e . Reactions can, o f course, take p l a c e i n s o l u t i o n (e.g., THF) a t lower temperatures; (4-11) (d) A p r a c t i c a l method has been found t o mix the i n i t i a t o r and polymer. The mix i s heterogeneous, as the i n i t i a t o r simply coats the monomer p a r t i c l e s , and i s s e n s i t i v e t o p a r t i c l e s i z e ; (e) Although there i s no d i r e c t evidence e i t h e r way, i t i s considered p o s s i b l e that the i n i t i a t e d p o l y m e r i z a t i o n may r e s u l t i n a d i f f e r e n t molecular s t r u c t u r e , s i n c e the p o l y m e r i z a t i o n temperature and heat or r e a c t i o n s are both lower f o r the i n i t i a t e d BA-DAB-BA. N e i t h e r cure r e a c t i o n s go to completion a t 177°C (350°F); ( f ) The e f f o r t reported h e r e i n i s a p a r t of an on-going p r o j e c t ; another p o r t i o n of which i s the mechanical response and f r a c t u r e s p e c t r a of the s u b j e c t m a t e r i a l s . I t i s hypothesized that the fracture/mechanics behavior w i l l be p a r t i c u l a r l y d e c i s i v e i n determining p o s s i b l e d i f f e r e n c e s i n molecular s t r u c t u r e .

Literature Cited 1. Hedberg, F.L. and Arnold, F.E., J. Appl. Polym. Sci., (1979) Vol. 24, 73-739. 2. Maximovich, M.G., Locherly, S.C., Kovac, R.F., and Arnold, F.E., Adhesives Age, (1977), 11, 40. 3. Eddy, S.R., Lucarelli, M.A., Helminiak, T.E., Jones, W.B., and Picklesimer, L.G., Adhesives Age, (1980), 23, 2. 4. Venanzi, J. Am. Chem. Soc., (1958), 219. 5. Daniels, J. Inorg. Chem., (1964), 23, 2936. 6. Luttinger and Colthup, J. Org. Chem., (1962), 27, 3752. 7. Colthup and Meriwether, J. Org. Chem., (1962), 27, 5169. 8. Meriwether, Leto, Colthup, Kennerly, J. Org. Chem., (1962), 27, 1591. 9. Luttinger, J. Org. Chem., (1962), 27, 1591. 10. Tsonis and Farona, J. Poly. Sci., (1979), 17, 1779. 11. Chalk and Gilbert, J. Poly. Sci., (1972), 10, 2033. RECEIVED May 11, 1982.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

19 Fracture Behavior of an Acetylene-Terminated Polyimide W. B. JONES, JR., T. E. HELMINIAK, C. C. KANG, M. A. LUCARELLI, and L. G. PICKLESIMER Air Force Wright Aeronautical Laboratories, Materials Laboratory, Wright-Patterson Air Force Base, OH 45433 The

fracture

behavior

of

an

acetylene-terminated

polyimide has bee Engineering fracture methods were adapted and applied to small quantities of this material.

Miniature

compact-tension (CT) specimens were fabricated and subjected to a programmed series of post-cure cycles. Fracture tests were then conducted at room temperature and at several elevated temperatures i n a In the e v a l u a t i o n of new m a t e r i a l s f o r p o t e n t i a l s t r u c t u r a l nitrogen purged environment. The fracture toughness a p p l i c a t i o n s , i t i s important that the s t r u c t u r a l c h a r a c t e r i s t i c s be measured as e a r l y as p o s s i b l e i n the e v o l u t i o n c y c l e o f the was found to vary with temperature and to depend m a t e r i a l . In response to a growing awareness of the r i s k inherent i n developing t o t a l l y new and "unknown" m a t e r i a l s , the A i r Force upon post-cure. These Fracture discrim-that i s developing an e v a l u a t i o n process f o rtests s t r u cclearly t u r a l polymers reduces the r i s k with concomitant i n c r e a s e i n investment. Interim specimens d i f f e r -along progressinate r e p o between r t s have the been given onresulting the e v a l u afrom t i o n the process, with example c h a r a c t e r i s t i c s measured f o r some polymers. ' ' cure cycles with only a small investment of e v a l u a t i o n During ent the adjustments i n emphasis and balance o f the methodologies, i t has become c l e a r that one o f the most d e s i r a b l e c h a r a c t material. e r i s t i c s o f a s t r u c t u r a l m a t e r i a l i s r e s i s t a n c e t o flaws and damage. Tough m a t e r i a l s are p r e f e r r e d f o r v i r t u a l l y a l l structural applications. At present, there i s a paucity of f r a c t u r e toughness data f o r polymers, and data f o r new polymers i s r a r e . T h i s i s due i n part to an unawareness of the value o f such data, and i n part to a l a c k of t e s t methods that use only small q u a n t i t i e s o f m a t e r i a l s .

This chapter not subject to U.S. copyright. Published, 1982, American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

246

POLYMERS WITH CHAIN-RING STRUCTURES

In an attempt to remove the l a t t e r c o n s t r a i n t , e f f o r t has been i n i t i a t e d to develop miniature f r a c t u r e specimens that can be used to c h a r a c t e r i z e l i m i t e d q u a n t i t i e s of new polymers. Hopefully, these e f f o r t s w i l l provide the " t o o l " r e q u i r e d to c h a r a c t e r i z e new polymers and w i l l be complimentary to the c o n t r i b u t i o n s of other i n v e s t i g a t o r s so that a meaningful f r a c t u r e data base w i l l be generated f o r a l l polymers. The f r a c t u r e c h a r a c t e r i s t i c s of a m a t e r i a l are important i n at l e a s t two c o n s i d e r a t i o n s . One use i s as a f i g u r e of merit f o r estimating the m a t e r i a l ' s s t r u c t u r a l c a p a b i l i t y i n design a p p l i ­ c a t i o n s . Another use i s to give the p h y s i c a l chemist i n s i g h t i n t o the mechanisms by which the molecular network formed during p o l y m e r i z a t i o n can r e s i s t mechanical damage and f r a c t u r e . H y p o t h e t i c a l l y , t h i s i n s i g h t can then provide g u i d e l i n e s f o r the synthesis of improved f r a c t u r The

Material

A r e l a t i v e l y l a r g e q u a n t i t y (approximately 200 gm) of an aromatic h e t e r o c y c l i c m a t e r i a l was a v a i l a b l e and was used to develop a f r a c t u r e t e s t method that could be used to c h a r a c t e r i z e m a t e r i a l s l i m i t e d i n a v a i l a b l e q u a n t i t i e s . This m a t e r i a l i s an acetylene-terminated polyimide, known as Thermid 600*, which has the molecular s t r u c t u r e shown i n F i g u r e 1. Although the m a t e r i a l i s a b i t d i f f i c u l t to work with i n the 100% s o l i d form, t h i s form was used to f a b r i c a t e specimens. Cure k i n e t i c s and Theolog­ i c a l data were measured and used to guide specimen f a b r i c a t i o n . Specimen F a b r i c a t i o n s The TH-600, i n the form of a f i n e l y p r e c i p i t a t e d powder, was h e l d i n a vacuum oven at 100°C f o r s e v e r a l days to remove solvent and absorbed moisture. Preweighed q u a n t i t i e s were then introduced i n t o a preheated (235°C) mold and 100 p s i pressure was immediately a p p l i e d using a h y d r a u l i c p r e s s . A f t e r d w e l l i n g f o r 1/2 hour at these c o n d i t i o n s , a c o n s o l i d a t e d and p a r t i a l l y cured bar 0.1" χ 0.5" χ 3" was removed from the mold. Bars made i n t h i s manner were l a t e r postcured to the c o n d i t i o n s shown i n Table 1. Using a diamond wafering saw, each bar was cut i n t o four equilength r e c t a n g l e s . Holes were then c a r e f u l l y d r i l l e d and a c e n t r a l s l o t with a chevron t i p was cut i n each r e c t a n g l e as shown i n Figure 2. The chevron t i p was then precracked by c a r e f u l l y tapping a razor blade i n the s l o t . I t i s noted that the specimen i s patterned a f t e r the ASTM compact t e n s i o n (CT) specimen used to t e s t metals. (·*) Fracture

Testing

S t i f f l i n k a g e and d e v i c e type g r i p s were f a b r i c a t e d and connected i n an I n s t r o n t e s t i n g machine. For each t e s t , the *Gulf

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

JONES

Behavior of an Acetylene-Terminated Polyimide

ET AL.

?

8 ï

? fi ?

HC=-C^< )^V> g^O g < )0r^ >^ C,CH c

1

1

r

c

c

r

Il

II

II

II

O

O

O

O

Figure L TABLE 1.

Molecular structure of Thermid 600. Postcure Conditions f o r TH-600 F r a c t u r e Specimens:

CURE 1 2 3 4 5

TEMP 290C

TIME 40 h r

372C 372C

1 hr 40 h r s

ATMOSPHERE Ai

N2

2.54 mm

ι 10.67 mm-

< T

1 y - Drill 2.08 mm

12.7 mm

5.99 mm

I

τ

1

Ύ 13.21 mm

Figure 2.

Compact tension specimen used in fracture tests.

American Chemical Society Library In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; 1155 16th SL N. W. ACS Symposium Series; American Chemical Washington, DC, 1982. MfMhlairtnn Π ΓSociety: οηηοβ

POLYMERS WITH CHAIN-RING STRUCTURES

248

specimen was pinned through the holes to the d e v i c e s using d r i l l rods as p i n s . A small L i n e a r V a r i a b l e D i f f e r e n t i a l Transformer (LVDT) was attached to measure the r e l a t i v e displacement between the d e v i c e s . For t e s t s at elevated temperatures, a s p l i t furnace was placed around the specimen and s t a b i l i z e d a t the t e s t temper­ ature. The I n s t r o n was run at 0.002"/min. cross-head r a t e , and the data were recorded as Force v s . LVDT displacement on an X-Y p l o t t e r . T y p i c a l data taken at three temperatures are shown i n F i g u r e 3. Although e f f o r t was made to have a s t i f f l o a d i n g frame and l i n k a g e , there i s enough compliance to permit s e v e r a l increments of crack growth i n the specimens at 20°C and 200°C. This i s evidenced by the sawtooth p a t t e r n s . P o s t - t e s t examination showed s t r i a t i o n s (See F i g . 4) on the f r a c t u r e s u r f a c e s that correspond to each i n t e r r u p t i o n i n crack growth. These f e a t u r e s were used to determin c a l c u l a t e the f r a c t u r temperatures between 250 and 300°C where the m a t e r i a l d i s p l a y e d slow crack growth and consequently d i d not e x h i b i t i n i t i a t i o n / a r r e s t or s u r f a c e markings. Since the l o a d i n g was l i m i t e d to constant displacement r a t e on the I n s t r o n , f r a c t u r e was i n i t i a t e d i n the high temperature specimens by tapping i n t e r m i t t a n t l y during the steady crack growth process. T h i s u s u a l l y produced small s u r f a c e markings with a s s o c i a t e d down-steps i n l o a d . The f r a c t u r e data were reduced

according to the e q u a t i o n :

v

'

χ f(a/w) 2

f(a/w)=(2+a/w)(0.886+4.64a/w-13.32 a /w

2

3

4

+ 14.72a3/w -5.6a^/w )

(1-a/w) 3/2 where:

a w b CR P

crack l e n g t h width thickness ~ * l l°ad f

a

u

r

e

The c a l c u l a t e d f r a c t u r e toughness values are tabulated i n Table I I , and g r a p h i c a l l y d i s p l a y e d i n Figure 5. Among a l l the data measured during t h i s study, there are v a r y i n g l e v e l s of confidence placed on the data, depending upon the post-cure and t e s t temperatures. D u p l i c a t e specimens were t e s t e d a t each of the twenty c o n d i t i o n s and m u l t i p l e data p o i n t s were obtained from each specimen. For Cure #3 t e s t e d a t 200°C, twenty-four (24) data p o i n t s were obtained from the two specimens and the s c a t t e r was w i t h i n + 10% of the average. Moderately high confidence i s placed i n these data. In other cases only four or f i v e data p o i n t s make up the average. There i s more s c a t t e r i n these data (up to +20%) thus these averages are marked (*) i n Table I I , and we are l e s s c o n f i d e n t of these r e s u l t s . Superim­ posed on the data s c a t t e r , which supposedly could be r e s o l v e d w i t h

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

19.

JONES

ET AL.

Behavior

Figure 4.

of an Acetylene-Terminated

Polyimide

Surface marks left by crack initiation/arrest

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

249

250

POLYMERS WITH CHAIN-RING

STRUCTURES

TABLE I I . F r a c t u r e Toughness, K MPa m Measured f o r TH-600 A f t e r Various Post-Cures TEMP CURE 1 2 3 4 5

20°C

200°C

250°C

300°C

880 710* 660* 890 600

680 490 460 800* 380

660* 440 530* 420* 360*

230*+ 270 270 160 330

* les + teste

1000

100 200 Temperature, C Figure 5.

300

Fracture toughness vs. temperature for Thermid 600 after various postcures.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

19.

JONES

E T AL.

Behavior of an Acetylene-Terminated Polyimide

251

supplemental t e s t i n g , another e f f e c t was noted that becomes more pronounced a t the e l e v a t e d temperatures. For a specimen repeatedl y t e s t e d a t constant temperature the f r a c t u r e toughness was high f o r s h o r t crack l e n g t h s , and became p r o g r e s s i v e l y lower as the crack l e n g t h i n c r e a s e d . T h i s e f f e c t was most pronounced f o r Cure #4 t e s t e d a t 300°C, with r e s u l t i n g data being shown below: a, mm 4.0 4.6 5.3 6.4

K ^ , MPa

^

230 220 170 70

T h i s e f f e c t was not observe d e n t a l l y were the most e x t e n s i v e l t o r s (4) have reported s i m i l a r r e s u l t s and have developed methods that would seem to d e a l e f f e c t i v e l y with t h i s behavior. The e f f e c t stems from the crack l e n g t h i n d i r e c t l y and depends r a t h e r on the time-dependence of the m a t e r i a l behavior. When the cracks are s h o r t , the specimen i s s t i f f , and hence loads to f a i l u r e q u i c k l y under the constant displacement r a t e . For the longer crack lengths, the more compliant specimen d i s p l a y s a longer time to f a i l u r e , with a s s o c i a t e d lower f r a c t u r e toughness. Further i n q u i r y i n t h i s area i s planned. Even while the above i s s u e s are only p a r t i a l l y r e s o l v e d , some conclusions can be drawn from the data d i s p l a y e d i n Figure 5. C l e a r l y , the f r a c t u r e toughness v a r i e s with temperature and i s i n f l u e n c e d by post-cure. E q u a l l y as c l e a r , the advancing postcure c o n d i t i o n s evaluated i n t h i s study p r o g r e s s i v e l y reduced the f r a c t u r e toughness o f the m a t e r i a l . Since post-cure i s p o p u l a r l y used to more f u l l y r e a c t the i n i t i a l r e a c t a n t s , develop higher g l a s s t r a n s i t i o n temperature, and h o p e f u l l y develop the m a t e r i a l ' s a b i l i t y to withstand higher use temperatures, the data i n F i g u r e 5 shown c a u t i o n should be e x e r c i s e d , a t l e a s t f o r t h i s m a t e r i a l . The small improvement i n the 300°C p r o p e r t i e s f o r Cure #5 m a t e r i a l came with s i g n i f i c a n t l o s s i n toughness a t temperatures below 250°C. The miniature Compact Tension f r a c t u r e specimen i s new, and as such, needs thorough e v a l u a t i o n b e f o r e the r e s u l t i n g data can be considered to be i n t r i n s i c m a t e r i a l behavior. In the i n t e r i m , i t i s b e l i e v e d the t e s t data w i l l be extremely u s e f u l to d e l i n e a t e between m a t e r i a l s having v a r y i n g degrees of toughness, f o r e v a l u a t i n g a m a t e r i a l ' s s e n s i t i v i t y to processing v a r i a t i o n s , and to serve as a t o o l f o r e x p l o r i n g the F r a c t u r e Process i t s e l f as an intermediate step t o developing tougher m a t e r i a l s . In summary, a f r a c t u r e t e s t has been s u c c e s s f u l l y a p p l i e d to a h i g h temperature polymer. Further developments o f t h i s t e s t are r e q u i r e d and are a l r e a d y underway.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

252

POLYMERS WITH CHAIN-RING STRUCTURES

Literature Cited 1. Eddy, S., Lucarelli, M., Helminiak, T., Jones, W., Picklesimer, L.; "Evaluating New Polymers as Structural Adhesives," Adhesives Age, Feb 1980, Vol. 23, No. 2. 2. Jones, W. B., et. al., "Evaluation of an Acetylene Terminated Sulfone Oligomer," presented at American Chemical Society Meeting, March 1980, Houston, TX. 3. ASTM-Standard E3999-78a, Paragraph 9.1.4, 1978. 4. Knauss, W. G., "Fracture of Solids Possing Deformation Rate Sensitive Material Properties," chapter in The Mechanics of Fracture, ed. by F. Erodogan, AMD - Vol 19, Amer. Soc. of Mech. Engineers, NY 1976. RECEIVED December 31, 1981

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

20 Synthesis and Characteristics of Poly(bisdichloromaleimides) 1

2

INDRA Κ. VARMA, GEORGE M. FOHLEN, and JOHN A. PARKER Ames Research Center, NASA, Moffett Field, CA 94035

Six bisdichloromaleimides having different aromatic structure dichloromaleic anhydrid thalene, (b) bis(m-aminophenyl)methylphosphine oxide, (c) 2,5-bis(p-aminophenyl) 1,3,4-oxadiazole, (d) 3,3bis(p-aminophenyl)phthalide, (e) 9,9-bis(p-aminophenyl) fluorene, (f) 10,10-bis(p-aminophenyl)anthrone. The effect of structural differences on thermal character­ istics of these compounds was investigated by dynamic thermogravimetry. Polymerization of these bisdichloromaleimides was carried by nucleophilic displacement of chlorine with 9,9-bis(p-aminophenyl)fluorene. The resulting polymers were characterized by IR spectroscopy and reduced viscosity measurements. Anaerobic char yields of these polymers at 800°C ranged from 55-60%. In presence of air, a complete loss of weight was observed between 600-650°C. Thermal cross-linking of these polymers was also investigated. The high-temperature capabilities and flame resistance of polymers may be influenced by the incorporation of aromatic or heterocyclic rings i n the backbone (1). We have earlier reported high char yields i n bismaleimides and biscitraconimides having fluorene, anthrone, and phthalein groups as bridging groups (2). Incorporation of certain elements such as phosphorus, chlorine, nitrogen, boron, and bromine i n synthetic polymers leads to an improvement i n flame retardation. Phosphorus-containing bisimide resins with good thermal s t a b i l i t y have been reported (3). An 1

This is Part II in a series. Current address: Indian Institute of Technology, Centre of Materials Science & Technol­ ogy, Delhi, Hauz Khas, New Delhi 110016, India. 2

0097-6156/82/0195-0253$06.00/0 © 1982 American Chemical Society

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING STRUCTURES

254

improvement i n l i m i t i n g oxygen index has been reported i n c h l o r i ­ nated aromatic polyamides (4). C h l o r i n e s u b s t i t u t i o n , however, d i d not a l t e r the char y i e l d s . I t would be of i n t e r e s t to i n v e s ­ t i g a t e the i n f l u e n c e of c h l o r i n e on char y i e l d s and on the flame r e s i s t a n c e of b i s i m i d e s . In t h i s paper we r e p o r t the s y n t h e s i s and c h a r a c t e r i z a t i o n of b i s d i c h l o r o m a l e i m i d e s having aromatic and h e t e r o c y c l i c groups i n the backbone. S i x b i s d i c h l o r o m a l e i m i d e s w i t h aromatic r i n g s as b r i d g i n g u n i t s were prepared by r e a c t i n g 2,3-dichloromaleic anhy­ d r i d e w i t h (a) 1,5-diaminonaphthalene, (b) bis(m-aminophenyl) methylphosphine oxide, (c) 2,5-bis(p-aminophenyl) 1,3,4-oxadiazole, (d) 3,3-bis(p-aminophenyl)phthalide, (e) 9,9-bis(p-aminophenyl) f l u o r e n e , and ( f ) 10,10-bis(p-aminophenyl)anthrone. Throughout the t e x t , b i s d i c h l o r o m a l e i m i d e monomers and polymers are r e f e r r e d to by the l e t t e r d e s i g n a t i o n accompanying sketch. Ο

Ο

Ο

C£ C2 Ο

Ο

Ο

Ο

WHERE Ar =

(a)

(c)

(b)

(d)

O

(e)

(f)

The b i s d i c h l o r o m a l e i m i d e s thus obtained may be polymerized thermally by the opening of the double bond. Such c r o s s - l i n k i n g

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

20.

VARMA

E T AL.

Poly(bisdichloromaleimides)

255

r e a c t i o n s have been e x t e n s i v e l y i n v e s t i g a t e d i n bismaleimides. Displacement o f c h l o r i n e by appropriate n u c l e o p h i l e s i s yet another way o f preparing polymers from b i s d i c h l o r o m a l e i m i d e s . N u c l e o p h i l i c s u b s t i t u t i o n r e a c t i o n s have been e f f e c t i v e l y e x p l o i t e d i n the s y n t h e s i s o f s e v e r a l c l a s s e s o f polymers. However, only scanty r e p o r t s are a v a i l a b l e on the a p p l i c a t i o n o f such r e a c t i o n s t o the displacement of c h l o r i n e i n b i s d i c h l o r o m a l e i m i d e s , although s e v e r a l examples o f displacement o f c h l o r i d e by nucleop h i l e s i n N - s u b s t i t u t e d dichloromaleimides e x i s t i n l i t e r a t u r e . Amines (5), phenols (6), and a l c o h o l s and t h i o l s (7) have been used as n u c l e o p h i l e s i n such r e a c t i o n s . R e l i e s and Schluenz (8) have reported the p r e p a r a t i o n of poly(maleimide-ethers) by using bisphenols and b i s d i c h l o r o m a l e imides. These polymers were s o l u b l e i n dimethylformamide (DMF) and d i m e t h y l s u l f o x i d e (DMSO Phosphorus-containing poly(maleimide-amines have poor thermal s t a b i l i t y and l i t t l e flame r e t a r d a t i o n (9). In the present work, condensation p o l y m e r i z a t i o n o f b i s d i chloromaleimides was c a r r i e d out with 9,9-bis(p-aminophenyl) fluorene.

The r e a c t i o n o f diamines and bisdichloromaleimides proceeds w i t h the displacement o f one c h l o r i n e . The r e s u l t i n g poly(maleimideamine) c o n t a i n double bonds as w e l l as c h l o r i n e i n the backbone. The presence o f double bonds i n the backbone o f these polymers a l s o makes them s u s c e p t i b l e to c r o s s - l i n k i n g r e a c t i o n s which may be i n i t i a t e d by heat. Experimental S t a r t i n g M a t e r i a l s . The diamines such as 1,5-diaminonaththalene o r 9,9-bis(p-aminophenyl)fluorene (BAF) were p u r i f i e d by c r y s t a l l i z a t i o n o r p r e c i p i t a t i o n . M e l t i n g p o i n t s (mp) o f the

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING STRUCTURES

256

d r i e d samples were found to be 187°C-188°C and 236°C-237°C, r e s p e c t i v e l y . Bis(m-aminophenyl)methylphosphine oxide (10) (mp 146°C-149°C); 3,3-bis(p-aminophenyl)phthalide (11) (mp 204°C-205°C); 10,10-bis(p-aminophenyl)anthrone (12) (mp 305°C-306°C) and 2,5-bis(p-aminophenyl) 1,3,4-oxadiazole (13) (mp 260°C-261°C) were prepared according to the methods reported i n the l i t e r a t u r e . The 2,3-dichloromaleic anhydride was a v a i l a b l e commercially ( A l d r i c h Co.). P r e p a r a t i o n of B i s d i c h l o r o m a l e i m i d e s . The method of M a r t i n et a l . (14) was used f o r the p r e p a r a t i o n of b i s d i c h l o r o m a l e i m i d e s . Diamines (0.005 mole) and 2,3-dichloromaleic anhydride (0.01 mole) were s e p a r a t e l y d i s s o l v e d i n g l a c i a l a c e t i c a c i d and the s o l u t i o n s were then mixed and heated slowly to r e f l u x temperature. A f t e r r e f l u x i n g f o r 2 h, the s o l u t i o n imides were p r e c i p i t a t e washed w i t h water u n t i l f r e e of a c e t i c a c i d . A f t e r d r y i n g , the products were r e c r y s t a l l i z e d from toluene/hexane. P r e p a r a t i o n of Polymers. The p o l y m e r i z a t i o n of the above prepared b i s d i c h l o r o m a l e i m i d e s was c a r r i e d out according to the method of R e l i e s and Schluenz (8). The 9,9-bis(p-aminophenyl) f l u o r e n e (0.001 mole) was d i s s o l v e d i n 10 ml of f r e s h l y d i s t i l l e d DMF c o n t a i n i n g 0.002 mole of t r i e t h y l a m i n e as an a c i d acceptor. To t h i s w e l l - s t i r r e d s o l u t i o n , 0.001 mole of a b i s d i c h l o r o m a l e imide ( a - f ) was added and the r e a c t i o n mixture s t i r r e d f o r 2 h. The polymer was p r e c i p i t a t e d by pouring the mixture i n t o an excess of water. The p r e c i p i t a t e a f t e r b o i l i n g i n acetone was d r i e d i n vacuum at 60°C-70°C. C h a r a c t e r i z a t i o n . I n f r a r e d s p e c t r a of b i s d i c h l o r o m a l e i m i de monomers and polymers i n KBr p e l l e t s were recorded, u s i n g a Perkin-Elmer 180 spectrophotometer. Elemental analyses were provided by Huffman L a b o r a t o r i e s . Mass s p e c t r a were recorded at 70 eV on a Hewlett-Packard MS 5980 instrument by the d i r e c t i n l e t procedure. A DuPont 990 thermal analyzer was used to evaluate thermal behavior of b i s d i c h l o r o m a l e i m i d e monomers and polymers. Reduced v i s c o s i t y of the polymers was determined i n DMF at 30°C w i t h a Cannon viscometer. Thermal p o l y m e r i z a t i o n was s t u d i e d by h e a t i n g a known weight of the m a t e r i a l from room temperature to the d e s i r e d temperature i n a g l a s s tube. The extent of c u r i n g was evaluated by e x t r a c t i o n w i t h DMF at room temperature. Results and D i s c u s s i o n C h a r a c t e r i z a t i o n of Bisdichloromaleimides. P h y s i c a l d e s c r i p t i o n , molecular weight, and a n a l y t i c a l data of the monomers are given i n Table I . M e l t i n g p o i n t s of these monomers were above 250°C. Thus, i n compounds (b), ( c ) , and ( f ) i n Table I , endothermic t r a n s i t i o n a s s o c i a t e d w i t h m e l t i n g was observed i n DSC at

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

20.

VARMA E T A L .

Table I .

Sample

257

Poly( bisdichloromaleimides)

Characterization of Bisdichloromaleimides

Formula

WC

H

N

Color

Cl

(a)

CieHeOi^NaClif

47.60 1.43 (47.57) ( 1 . 3 2 )

6.14 (6.16)

(b)

C21H11O5N2CUP

47.02 2.23 (46.49) (2.03)

5.43) 25.10 542 Yellow (5.17) (25.83)

(c)

022Ηβ05Νι»01ι»

49.06 1.67 (48.17) ( 1 . 4 6 )

(d)

C2eHi206N2Clif

56.12 (54.9)

(e)

03 3 ^ 6 0 ^ 2 0 1 ^

63.03 2.75 (61.49) (2.48)

644 Yellow 20.63 4.39 (4.34) (21.74)

(f)

θ3*Ηΐ6θ5Ν 01ι*

2.73 62.23 (60.53) (2.37)

20.74 672 L i g h t 4.23 green (4.15) (20.77)

2

2.20 (1.96)

10.21 (10.22)

454 L i g h t 31.04 brown (30.83)

25.95 548 Yellow (25.55)

24.11 612 Yellow 4.44 (4.57) (22.87)

'Represents the molecular i o n i n the 70 eV mass s p e c t r a o f b i s d i ­ chloromaleimides; f i g u r e s i n parentheses a r e c a l c u l a t e d v a l u e s .

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

POLYMERS WITH CHAIN-RING STRUCTURES

258

265°C, 369°C, and 300°C, r e s p e c t i v e l y . Elemental analyses agree w e l l w i t h the assigned s t r u c t u r e s of the monomers. Electron-impact-induced fragmentation p a t t e r n s of 2,5-bis(pdichloromaleimidophenyl) 1,3,4-oxadiazole (compound c ) ; 3,3-bis(pdichloromaleimidophenyl)phthalide (compound d ) ; and 10,10-bis(pdichloromaleimidophenyl)anthrone (compound f ) are given i n F i g u r e 1. The common f e a t u r e s present i n the mass s p e c t r a of these compounds are summarized i n Table I I . A l o w - i n t e n s i t y molecular i o n peak was observed i n most o f these monomers, w i t h the exception of compounds (a) and (b). Loss of carbon d i o x i d e from the molecular i o n (M-44) was i n d i c a t e d o n l y i n compound ( d ) , which c o n t a i n s a p h t h a l i d e group. Carbon d i o x i d e may be e l i m i nated from t h i s s i t e . S i m i l a r fragmentation p a t t e r n s have e a r l i e r been obtained w i t h corresponding bismaleimides and b i s c i t r a c o n i m i d e s (15) The other fragment ion the l o s s o f the d i c h l o r o m a l e i m i d y l group (M-164) (compounds a, b, and c) and dichloromaleimidophenyl group (M-240) (compounds b, d, e, and f ) from the molecular i o n . Cleavage of the d i c h l o r o m a l e i m i d y l group i s r e s p o n s i b l e f o r the appearance of fragment ions at m/z 122 (C3C1 0)+ and 87 (C3C10) . However, the corresponding (M-122)+ i o n was absent i n b, c, d, and f . R e l i e s and Schluenz (16), w h i l e working the N - a r y l dichloromaleimides, have observed that the tendency of charge to remain i n the isocyanate h a l f on +

+

2

+ c ci o 3

M-122

/R

COR

-/QV ^

2

N=c=dl + c c i a 3

'

+

2

M/Z 122

M-164

M-240

cleavage depends on the e l e c t r o n donating or e l e c t r o n withdrawing e f f e c t of the s u b s t i t u e n t . Compounds (a) and ( c ) , i n which such an i o n was observed, c o n t a i n a naphthalene or f l u o r e n e r i n g , whereas i n other cases e l e c t r o n - a t t r a c t i n g groups (carbonyl, oxad i a z o l e , or phosphine oxide) are present i n the molecule. A f r a g ment i o n at m/z (M-148) was observed i n some compounds. T h i s could a r i s e by the l o s s o f the ( C ^ C ^ O N n e u t r a l fragment from the maleimide group. Appearance of the corresponding (M-80) and (M-94) fragments has e a r l i e r been observed i n bismaleimides and b i s c i t r a c o n i m i d e s (15). Simultaneous l o s s of CO2 (from the p h t h a l i d e group) and of the d i c h l o r o m a l e i m i d y l group may account f o r the fragment i o n at (M-208) i n compound (d). In compound ( b ) , fragment ions of the h i g h i n t e n s i t y (40% of base peak) were +

+

+

+

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

20.

VARMA

E T AL.

Poly(bisdichloromaleimides)

% 'aoNVQNnav

3AI±VH3H

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

259

260

POLYMERS WITH CHAIN-RING

STRUCTURES

Table I I . R e l a t i v e Abundances (% Base Peak) of Some Fragment Ions i n the 70 eV Mass Spectra of B i s i m i d e s * Sample a (Mol wt) (454) (M) + ^ (M-35) (M-44)+ (M-63)+ (M-122)+ (M-148)+ (M-164)+ (M-208)+ (M-240)+ (M-244)+ (M-362)+ (87)+ (122)+ (164)+ (239)+ (240)+ (268)+ +

(542)

65.8 (4) 2.2

66 (4) 47.0

-8.5

-40.9

36.8 (3) 14.1 5.8

-100 -67.6

(2) 11.5 (2) 3.4 (2)

-

23.2 (2) 16.6 (2)

100 (2) 33.7 (3) 8.8 (2) 7.7 11.6

(548) 14.7 (4)

-25.1

(2) 6.6 (2)

-14.7 100

(612) 9.2 (3)

-22.1 -33.6

(3)

(3) 100 (3)

-53.0

(2) 10.6 (3) 5.5 16.6 12.9 12.9

(644)

(672)

59.6 (3)

16.4 (3]

-11.7 -20.2 -76.6 -100

-100 (3) -9.5

(2)

(2)

59.6 (2) 13.8 9.6 98.9 41.5

-

47.6 (2] 11.6 (2] 7.4 93.7 26.5 47.1

The numbers i n parenthesis next to i n t e n s i t y values i n d i c a t e the number of peaks a s s o c i a t e d w i t h the c h l o r i n e i s o t o n i c c l u s t e r s f o r each i o n . I n t e n s i t i e s given are f o r the a l l CI peaks o f each c l u s t e r . 3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

20.

VARMA

E T AL.

261

Poly(bisdichloromaleimides)

observed a t M - l , M-15, M-35, and M-63. The M-l i o n may a r i s e by l o s s o f hydrogen and formation o f b r i d g e d phosphafluorenyl i o n (17). The scheme i n Sketch 4 may account f o r the appearance o f these i o n s . The IR s p e c t r a o f the compounds showed c h a r a c t e r i s t i c absorp­ t i o n s owing t o the imide group (at 1790 cm" and 1725 ±5 cm" ), the double bond (at 1620 ±10 cm" ), and C-Cl (at 880 cm" ) ( F i g . 2a). I n monomer (d) a b s o r p t i o n owing to the p h t h a l i d e group i s observed a t 1730 cm" ( F i g . 2b). I n monomer ( f ) the c a r b o n y l group a b s o r p t i o n appears a t 1660 cm" . I n monomers ( b ) , absorp­ t i o n s owing t o Ρ - 0 (at 1190 cm" ), P-C H (at 1425 cm" ), C H (at 1480 cm" ), and C-N (at 1380 cm" ) were a l s o observed. 1

1

1

1

1

1

1

1

6

1

5

6

5

1

Curing o f B i s d i c h l o r o m a l e i m i d e s . D i f f e r e n t i a l scanning c a l o r i m e t r y was used as a t o o of b i s d i c h l o r o m a l e i m i d e s range o f 270°C-450°C was observed i n these samples. T h i s may be a t t r i b u t e d t o thermal p o l y m e r i z a t i o n by opening o f the double bonds. I t may a l s o a r i s e by thermal decomposition o f b i s d i c h l o r o ­ maleimides. Thermogravimetric a n a l y s i s o f these monomers d i d i n d i c a t e a l o s s i n weight above 300°C. I t was, t h e r e f o r e , decided t h a t we would study thermal p o l y ­ m e r i z a t i o n o f b i s d i c h l o r o m a l e i m i d e s a t 300°C f o r 30 min. The r e s u l t i n g product was s o l u b l e i n DMF to a great extent (Table I I I ) w i t h the exception o f compound (b). T h i s i n d i c a t e s the absence o f thermal p o l y m e r i z a t i o n under these c o n d i t i o n s . Anaerobic char y i e l d s o f these t h e r m a l l y t r e a t e d b i s d i c h l o r o m a l e i m i d e s depended on t h e i r backbone s t r u c t u r e ; a very low v a l u e was obtained i n com­ pounds (a) and ( c ) ; compound (b), which contained phosphorus, was most s t a b l e . Condensed phase r e a c t i o n s are i n f l u e n c e d by the presence o f phosphorus i n these polymers. An almost l i n e a r r e l a ­ t i o n s h i p i s observed between anerobic char y i e l d s a t 800°C and b r i d g e formula weight o f b i s d i c h l o r o m a l e i m i d e ( F i g . 3 ) . C h a r a c t e r i z a t i o n o f Bisdichloromaleimide-Amine Polymers. The s t r u c t u r e s o f the polymers (a) to ( f ) were confirmed by t h e i r IR s p e c t r a ; absorptions owing t o the secondary amine were observed a t -3300 cm" and 1509-1515 cm" , and a b s o r p t i o n owing to the c a r ­ b o n y l group o f the imide r i n g was observed at 1720 cm" . An a d d i ­ t i o n a l band was observed around 1660 ±2 cm" ( F i g . 4 ) . T h i s has been assigned t o the c a r b o n y l group conjugated w i t h the n i t r o g e n of secondary amine (6, 9 ) . The i n t e n s i t y o f the C-Cl band a t 880 cm" was reduced i n the polymers, r e l a t i v e to that o f the monomers. Elemental analyses o f these polymers agreed w i t h the assigned s t r u c t u r e s (Table I V ) . The reduced v i s c o s i t i e s o f the polymers were i n the range o f 0.1-0.72 £l/g (Table V ) . 1

1

1

1

1

Thermal Behavior o f Polymers. Thermogravimetric analyses o f the polymers were c a r r i e d out both i n an a i r and n i t r o g e n atmo­ sphere (flow r a t e o f 100 cm /min) a t a h e a t i n g r a t e o f 10°C/min. 3

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

262

POLYMERS WITH CHAIN-RING

STRUCTURES

Ζ

Ο

ο

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

Figure 2α.

1R spectra of 1,5-bisdichloromaleimido naphthalene.

f

5-

S

Ι

>

Η

ρ

> w

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

264

POLYMERS WITH CHAIN-RING

STRUCTURES

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

20.

VARMA

ET AL.

Table I I I .

Sample

Anerobic Char Y i e l d s of Bisdichloromaleimides Heated at 300°C f o r 30 min

Bridge formula weight 126 214 220 284 316 344

(a) (b) (c) (d) (e) (f)

265

Poly (bisdichloromaleimides)

Y

c

(%)

10 66 34 52.5 55.5 57

S o l u b i l i t y i n DMF 100 6 62.3 86 100 100

80 r

Figure 3.

Effect of bridge formula weight on anaerobic char yields (at 800°C) of bisdichloromaleimides.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

266

POLYMERS WITH CHAIN-RING

STRUCTURES

%'30NVl±IIAISNVa±

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

20.

νA R M A

Ρoly (bisdichloromaleimides)

ET AL.

Table IV.

267

C h a r a c t e r i z a t i o n o f Poly(maleimide-amines) Elemental a n a l y s i s * (%)

Sample

Formula of repeat

unit

c

H

Cl

Ν

(a)

C i» 3 H2 i»N if 0 if C12

69.39 (70.6)

3.45 (3.2)

7.35 (7.67)

10.84 (9.5)

(b)

Cif 6H29Nif0sCl2

66.24 (67.48)

3.78 (3.54)

6.81 (6.84)

8.21 (8.56)

(c)

Cif7H 6N60 Cl

(d)

C53H3oNif0 Cl

71.34 (71.6)

3.62 (3.37)

6.49 (6.3)

6.71 (7.88)

(e)

C5eH3ifNif0ifCl2

75.65 (75.65)

3.85 (3.69)

6.01 (6.08)

7.39 (7.6)

(f)

C5 9H3ifNif05Cl2

73.76 (75.47)

3.64 (3.6)

5.80 (5.97)

6.04 (7.4)

2

5

6

2

F i g u r e s i n parentheses a r e c a l c u l a t e d v a l u e s .

Table V.

Polymer

Anaerobic Char Y i e l d s and Decomposition Temperatures of Bisdichloromaleimide-Amine Polymers

Formula weight *]sp/c* of repeat u n i t (dl/g)

730 818 824 888 920 948

(a) (b) (c) (d) (e) (f)

0.56 0.13 0.22 0.72 0.27 0.41

Τi

(°c)t

Y ** (%) c

Air

Nitrogen

335 310 330 340 360 350

350 340 335 400 400 390

A i r Nitrogen 500 480 520 525 510 525

580 550 540 525 580 550

*In DMF a t 30°C a t a c o n c e n t r a t i o n o f 0.2 ±0.02 g / d l . *Anaerobic char y i e l d a t 800°C. t T ^ = i n i t i a l decomposition temperature. ^max temperature o f maximum r a t e o f decomposition. =

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

61 55 56 60 60 60

POLYMERS WITH CHAIN-RING STRUCTURES

268

The polymers were s t a b l e up to 300°C i n a i r and n i t r o g e n but s t a r t e d l o s i n g weight at h i g h e r temperatures ( F i g . 5 ) . The anaerobic char y i e l d s of the polymers at 800°C were i n the range of 55%-61% (Table V ) . Presence o f fused aromatic r i n g s i n these polymers apparently d i d not i n f l u e n c e the char formation tendency. The temperature o f the maximum r a t e o f decomposition was reduced i n the presence of a i r , and an almost complete l o s s i n weight occurred at about 600°C (Table V ) . C r o s s - L i n k i n g Reactions o f Polymers. B i s d i c h l o r o m a l e i m i d e amine polymers c o n t a i n (a) a double bond i n the maleimidyl group, (b) c h l o r i n e , and (c) secondary amine group (-NH-). I t may be p o s s i b l e to c r o s s - l i n k them e i t h e r by the opening of the double bond (thermal p o l y m e r i z a t i o n ) o r by the n u c l e o p h i l i c displacement of c h l o r i n e by the secondar amine Th r e p r e s e n t a t i v reactio scheme f o r such r e a c t i o n such r e a c t i o n s may be evaluate y y dimethyIformamide· Thermal c r o s s - l i n k i n g r e a c t i o n s were evaluated by h e a t i n g polymers ( a ) , ( b ) , ( d ) , and ( f ) a t 300°C f o r 30 min. Solubility of the r e s u l t i n g product i n DMF was c o n s i d e r a b l y reduced (OL,

+H N-R-NH 2

2

Discussion Synthesis o f b i s ( p y r r o l e ) monomers. The condensation of e t h y l d i a c e t y l succinate with amines t o give d i a l k y l e s t e r s of Ν s u b s t i t u t e d p y r r o l e s proceeds i n near q u a n t i ­ t a t i v e y i e l d s t o the b i s ( d i c a r b o e t h o x y dimethyl p y r r o l e ) . The c o n d i t i o n s f o r t h i s r e a c t i o n a r e the same as those used by e a r l i e r workers t o prepare mono dicarboxy p y r r o l e d e r i v a t i v e s 03-8). Upon c o o l i n g of the a c e t i c a c i d r e a c t i o n s o l u t i o n the product, b i s p y r r o l e d e r i v a t i v e , c r y s t a l l i z e s out and i s recovered i n s u f f i c i e n t p u r i t y t o be used without f u r t h e r p u r i f i c a t i o n . Attempts t o hydrolyze the b i s ( d i c a r boethoxy p y r r o l e ) d e r i v a t i v e s i n aqueous NaOH proved unsuccessful due t o the h i g h degree o f i n s o l u b i l i t y . I f , however, the h y d r o l y s i s was begun i n a l c o h o l i c media, the r e a c t i o n progressed q u i t e r a p i d l y to give the b i s ( d i ­ carboxy p y r r o l e ) . Anhydride formation has been accomplished by r e f l u x i n g the t e t r a a c i d i n a c e t i c anhydride. Here again, the product i n high p u r i t y can be obtained merely by c o o l i n g the r e a c t i o n mixture. As can be seen from Table I , the y i e l d s o f the v a r i o u s b i s p y r r o l e monomers are a l l very h i g h , even though no e f f o r t s were made t o optimize the y i e l d s f o r these syntheses.

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

276

POLYMERS WITH CHAIN-RING

STRUCTURES

The m e l t i n g p o i n t s of some of the d e r i v a t i v e s are summarized i n Table I I . Other analyses performed on these samples (NMR, I n f r a r e d , Elemental Analyses) are a l l c o n s i s t e n t with the proposed s t r u c t u r e s . P o l y i m i d e s . The p r e p a r a t i o n of the polyimides proceeds through poly(amic a c i d ) i n t e r m e d i a t e s . The poly(amic a c i d ) can be i s o l a t e d p r o v i d i n g the temperature of the condensation i s p r o p e r l y c o n t r o l l e d . At 50°C the s t r u c t u r e formed i s almost e n t i r e l y poly(amic a c i d ) w h i l e at the s o l v e n t r e f l u x temperature almost 100% polyimide i s formed. The presence of the amic a c i d i s a l s o c l e a r l y shown by i n f r a r e d and TGA curves. F i g u r e 1 shows the weight l o s s of the amic a c i d s t r u c t u r e at 150-230°C. F i f t e e n percent of the weight of the sampl l o s s appears t o be o as w e l l as dehydration. Although q u a n t i t a t i v e estimates have not been made, i t appears as though i n c e r t a i n samples, a p o r t i o n of the weight l o s s corresponds to the t h e o r e t i c a l l o s s f o r water i n the c y c l i z a t i o n (5% f o r Sample 34b). DSC scans of the poly(amic a c i d ) show a broad endotherm at 160-175 C which probably corresponds with a r i n g c l o s u r e to the imide. A f t e r that p o i n t decomposition can be seen past 400 C. P r e p a r a t i o n of the polymer at a h i g h e r temperature (160 C) gives almost e x c l u s i v e l y p o l y i m i d e . The r e s u l t s of p o l y m e r i z a t i o n s u s i n g s e v e r a l dianhydrides and diamines are summarized i n Table I I I . Departure from the t h e o r e t i c a l carbon and hydrogen analyses (Table IV) f o r samples C and D probably i n d i c a t e s incomplete c y c l i z a t i o n of the imide s t r u c t u r e . No f r e e amic or c a r b o x y l i c a c i d f u n c t i o n a l i t y i s found i n the IR s p e c t r a of these samples. The TGA curves (Figures 2 & 3) show l i t t l e or no i n i t i a l weight l o s s up to 400 C. As i s common f o r aromatic polyimides these polymers are a l l brown to g o l d i n c o l o r and are s o l u b l e i n 97% H 2 S O 4 . Inherent v i s c o s i t i e s as shown i n Table IV are low, being l e s s than 0.5 d l / g . , i n d i c a t i n g low molecular weight. While f i l m s could be prepared from the poly(amic a c i d s ) , which were converted to polyimides on heat treatment (200-250 C f o r s e v e r a l h o u r s ) , they were very b r i t t l e and broke on h a n d l i n g . T h i s i s not s u r p r i s i n g i n view of the low inherent v i s c o s i t y (- (0.01)

80%

96%

87%

0.175

-—- (0.08)

93%

94%

95%

0.10

--

0.10

(0.05

- < ( ^ o - ( Ô ) - (0.05

0.10

(0.05)

95%

98%

95%

0.10

- < Ô > — S0 -(0.05)

87%

95%

98%

2

TABLE I I PROPERTIES OF PYRROLE DERIVATIVES

i»3 0

X

CH„

c-x R

Ν CH

ESTER 140-143

0

-C-X u 0

X (MPT)°C ACID 225-230(DECO) 220-225 DECO

-0r

ANHYDRIDE

194-204 MELT/I DECOMP

210(230 DECO) 84-85^

-270 (DECO)

-310°(DECO)

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

Figure 1. Thermogravimetric analysis of typical polyamic acid.

ATMOSPHERE-AIR

e

HEATING RATE 30 C/MIN.

to 00 In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

21.

279

Thermally Stable Polyimides

STACKMAN

T A B L E PREPARATION

Ο

Χ

σ

E X N O .

I I I O F

C H

3

C H

C H

3

C H

R

=

R

POLYIMIDES

β

3

0

3

SOLVENT

1

T E M P . , ° C

CONV.,%

150

96

130

98

130

87

A

ACETAMIDE Β

DIMETHYL FORMAMIDE

C

N , N DIMETHYL ACETAMIDE

D

N , N DIMETHYL ACETAMIDE

r— TABLE I V PROPERTIES Polyimide

Analysis Analysis ( 5 % Wt. Loss )

OF POLYIMIDES Composition Calculated

Ex No,

I.V. dl/g

A

0.29

470°C

76. 4

4.5

Β

0.38

455

63. 4

C

0.48

440

D

0. 38

420

a

0.1%

a

Cone,

of Polyimides Found

Ν

Ç

H

8.93

76.5

5.72

8.87

3.7

7.41

62.8

4.1

7.23

72. 7

4.3

8.48

68

4.35

8.05

70. 5

4.2

11.58

67.7

5.42

C

Η

Ν

10.4

i n 99% I^SO^

In Cyclopolymerization and Polymers with Chain-Ring Structures; Butler, G., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1982.

Figure 2. Thermogravimetric analysis of polyimides, heating rate 30°C/min.

W ce

Ο H

§

H

ce

ο

5

1

Ο

ï

S

H

2§

w *»

ce

*