POLYMER CHEMISTRY

POLYMER CHEMISTRY

Bruno Vollmert

Translated from the German by

Edmund H. Immergut

S pringer-Verlag

Berlin • Heidelberg • New York 1973

Bruno Vollmert Director

Polymer Institute University of Karlsruhe

Edmund H. Immergut Adjunct Professor

Institute of Polymer Research Polytechnic Institute of Brooklyn

All rights reserved.

No part of this book may be translated or reproduced in any form without written

permission from Springer-Verlag.

© 1973 by Springer-Verlag New York Inc.

Softcover reprint of the hardcover I st edition 1973

Library of Congress Catalog Card Number: 72-175905

ISBN-13: 978-3-642-65295-0 DOl: 10.1007/978-3-642-65293-6

e-ISBN-13: 978-3-642-65293-6

FOREWORD

There is, at present, no scarcity of polymer textbooks in the English language. Some of them attempt to cover the entire field, others focus their attention on certain parts of it, e.g., organic chemistry, physical chemistry, solid state physics, etc. This situation must necessarily raise the question, "Why publish another book?" and, even more, "Why translate a book which exists already in German?" and is to a lesser or greater extent legible and comprehensible to many English­

speaking scientists. It appears that a justification can be found in the special character of its content

and presentation. As far as content is concerned, Vollmert's book is more encompassing than most existing treatises and, in this sense, almost represents a hybrid between a "textbook" and a "handbook." Numerous figures and tables convey directly a wealth of data. On the other hand, the text is designed to be educational and, in many instances, goes a long way to explain why certain properties are observed and why certain processes take place. These excursions into the intellectual clarification of somewhat complicated phenomena are a refreshing and unusual interruption of the main stream which presents synthesis, characteriza­tion and properties of polymeric systems in the classical way.

In the second chapter emphasis is placed on the systematic and complete description of the different types of polymerization processes and of the cor­responding techniques with a very welcome chapter on enzymatic and protein syntheses, which can usually not be found in textbooks of polymer chemistry.

In Chapter 3 the properties of the individual macromolecule are presented in much detail. These details are important but are usually treated in only a superficial manner; here experimentation and theory are receiving equal consideration.

In the last chapter - states of molecular aggregation - one finds an up-to-date exposition of the recent important developments in the field of polymer crystalliza­tion and deformation.

The writer of this blend of preface and review hopes that this book's special features which have just been enumerated will provide for it a useful and enduring place in the literature.

v

H. F.MARK Institute of Polymer Research

Polytechnic Institute of Brooklyn

AUTHOR'S PREFACE

Macromolecular chemistry, or polymer chemistry, founded by the scientific work of H. Staudinger, W. H. Carothers, W. Kuhn and H. F. Mark, can be called "Variations on a Theme of 'Chains.' "

The first part of this book, after a brief survey of different chain structures (Chapter I), demonstrates the types of synthesis through which long, chain-like macromolecules are formed from small monomer molecules (Chapter 2). Through the nature of the monomer and through the nature and conditions of the polymer synthesis, the primary structure, i.e. the type and arrangement of structural units in the chain, is defined. The primary structure may be changed, intentionally or unintentionally, by chemical reactions of the polymer with low molecular weight reagents or with other polymers. All matters concerning the primary structure have been dealt with in Chapter 2.

The third chapter is devoted to the discussion of factors which do not concern the arrangement of the single links in the chain, but the chain as a whole, thus, the chain length (molecular weight and molecular weight distribution) and the three­dimensional arrangement of the chain, i.e. the secondary structure. If a macro­molecule is not influenced by forces of interaction, the long chain exists as a loosely and irregularly folded coil - a "random coil." Random coils exist in dilute polymer solutions as rubberlike, swollen gel particles, which differ from usual material particles in a characteristic manner in that their average density depends on their mass in accordance with theoretical principles, a phenomenon otherwise only found with material "particles" of the magnitude of fixed stars (the reasons are very different indeed).

While the third chapter deals with the properties of the single or free-mOving macromolecule, the fourth and last chapter is devoted to the discussion of the different forms of the aggregated state of polymers: the solution, the gel, the rubber, the glass and the fiber.

In the aggregated state, the random coil remains the preferred element of structure. The characteristic property of the Single coil, its entropy-elasticity, is carried over into the macroscopic polymer sample where it appears as rubber elasticity. The mobility of the chain defines the temperature at which the rubber freezes to a glass. The degree of regularity of the primary structure decides whether or not, and to what extent, a polymer crystallizes. Within the sphere of crystal­linity, the random coil changes into other secondary structures - the helix,

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viii Author's Preface

double-helix, folded chain-bundl~ or chain rope. Different secondary structures can exist together in an equilibrium state.

The author of a textbook is obliged to select scientific topics or problems for discussion, and there is no general formula which enables him to appraise the degree of importance of any particular topic. It is not possible, therefore, to write a book in which everybody will find every topic which he considers important enough to warrant representation. Furthermore, in some cases, different opinions or theories are held on the same problem. The reader will find all this in monographs and review articles.

All chapters of this edition are revised, enlarged, and in parts newly written. The question has often been posed as to whether macromolecular chemistry

ought to be regarded as an autonomous discipline of the chemical sciences, in the same way as inorganic, physical or organic chemistry, or whether it could be taught better as a section of organic and physical chemistry. This is not a question of a basic nature, but one of expediency, and capacity of the specialists. If at a university, the professors of organic and inorganic chemistry could decide upon which sections of physical chemistry they would teach in their lectures, the chair of physical chemistry would be superfluous. This situation, of course, assumes that the two scientists, the inorganic and organic chemist, are not only willing to teach physical chemistry, but also able to do so. This could happen. I feel we have a similar situation with regard to polymer science.

During the past few years, I have often been asked for the translation of the Aristotle quotation on the first page of the German edition. Here is the translation:

"The sciences, pursued for their own sake, that is, for the sake of knowledge, deserve to be called wise, to a greater extent than the sciences pursued for the sake of commercial profit. All of these may be more necessary, but none is more worthy."

This quotation was inserted as a dedication to, and in memory of a teacher whom I particularly respect. I have to admit that in our world, worthiness is seldom preferred to benefit and advantage. However, it is perhaps a good thing that we remember from time to time that at all times, men have lived, who did not only claim it but have also done it. The full meaning of the quotation becomes clear only when we take into consideration Aristotle's own interpretation: "Of dignified and divine things we have only little knowledge. But although we may hardly reach up to these higher regions, this kind of knowledge, because of its greater dignity, is more desirable to us than all things of our own world - just as we are more blest when we obtain only a brief glance of a beloved being than when we behold many other and even important things with great clarity."

It was a long time ago when Aristotle wrote these words but their message makes us a little more thoughtful in view of the enormous efforts we expand in

Author's Preface ix

exploring "all the things of our own world" - in view also of the efforts which were necessary to write and edit this book. I would very much like to thank everybody who has helped me, above all, my wife, who typed my first and hardly to be deciphered manuscript. I would like to thank Dr. Immergu t for great interest in and perseverance with the translation and Mrs. Immergut for the typing of the English manuscript. I also wish to thank all colleagues who have helped me by means of valuable advice and discussion. I particularly wish to thank Professor H. Mark for his kind willingness to write a foreword to this book.

I can only hope that the reader will find something of interest in these pages.

Karlsruhe, May 1973 B. VOLLMERT

TRANSLATOR'S NOTE

This book employs an unusual but highly convenient numbering system for all tables and figures. Thus each table and figure is numbered after the page number on which it appears. For example: Figure 485 appears on page 485 and Table 508 appears on page 508. This makes it very easy to find any figure or table immediately without the need, as with other books, of thumbing through a number of pages before locating it. We hope that the reader will quickly become used to this system and appreciate its simplicity.

New York, May 1973 E. H. IMMERGUT

TABLE OF CONTENTS

Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..... .

1 General characterization .............................. 1 2 The macromolecular concept. . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 3 Molecular weight and polymolecularity .................... 4 4 Classification according to molecular size ... . . . . . . . . . . . . . . . . 5 5 Inorganic and organic polymers. . . . . . . . . . . . . . . . . . . . . . . . . . 6 6 Natural and synthetic macromolecules . . . . . . . . . . . . . . . . . . . . . 7

Structural Principles. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

11 Chain structure, degree of polymerization. . . . . . . . . . . . . . . . . . . 9 12 Copolymers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 13 Branched and cross-linked polymers. . . . . . . . . . . . . . . . . . . . . . . 24 14 Primary, secondary, and tertiary structures . . . . . . . . . . . . . . . . . . 30

2 Synthesis and Reactions of Macromolecular Compounds. . . . . . . . . . . . 33

21 Synthesis of macromolecules with C-C chains through polymeriza tion of olefinic unsaturated com pounds. . . . . . . . . . . . . . . . . . . . . . . . 40

211 Radical polymerization. . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 2111 Chain initiation /50 2112 Chain propagation /54 2113 Chain termination /58 2114 Kinetics of radical polymerization /73 2115 Copolymerization /94 2116 Block- and graft-copolymers /148 2117 Techniques of radical polymerization /149

212 Ionic polymerization . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 163 2121 Ionic polymerization with quantitative dissociation

of the initiator (stoichiometric polymerization) /164 2122 Ionic polymerization with initiators which dissociate

only partly /176 2123 Polymerization with hydride shift /179 2124 Techniques of ionic polymerization /184

213 Polymerization with complex catalyst systems 2131 Stereochemistry of vinyl polymers /185

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xii Table of Contents

2132 The mechanism of polymerization with complex initiators /190

214 Other methods for the synthesis of macromolecules with carbon-carbon chains. . . . . . . . . . . . . . . . . . . . . . . . .. 201

22 Synthesis of macromolecules with heteroatoms in the chain. . . . . .. 206

221 Polycondensations and polyadditions .................. 207 2211 Polyesters and polyamides /207 2212 Other polycondensations /222 2213 The technique of polycondensation /234 2214 Polyaddition /236

222 Polymers from heterocyclic compounds and formaldehyde. . . .. 244 2221 Lactam polymerization with water /244 2222 The anionic polymerization of caprolactam /245 2223 The polymerization of N-carboxyl-amino acid anhydrides /248 2224 The polymerization of monoisocyanates /249 2225 The polymerization of cyclic ethers /249 2226 Polyformaldehyde /251

23 Enzymatic synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 255

231 Synthesis of polysaccharides . . . . . . . . . . . . . . . . . . . . . . .. 256

232 The enzymatic synthesis of nucleic acids .. . . . . . . . . . . . . .. 258 2321 Structure of DNA /258 2322 Synthesis of DNA /260' 2323 DNA as the carrier of genetic information /270

233 Enzymatic protein synthesis ........................ 277

234 The biosynthesis of natural rubber .. . . . . . . . . . . . . . . . . .. 281

24 The stepwise synthesis of proteins. . . . . . . . . . . . . . . . . . . . . . .. 281

241 The Merrifield Procedure .......................... 284

25 Graft-copolymers and block-copolymers. . . . . . . . . . . . . . . . . . .. 288

251 Synthesis of graft-copolymers. . . . . . . . . . . . . . . . . . . . . . .. 288 2511 Graft copolymerization by means of radicals /291 2512 Preparation of graft-copolymers with the aid of

functional groups /296 2513 Graft-copolymers through copolymerization /299

252 Preparation of block-copolymers. . . . . . . . . . . . . . . . . . . . .. 301

26 Purification of polymers .............................. 305

27 Chemical transformation of polymers. . . . . . . . . . . . . . . . . . . . .. 307

271 Degradation reactions (chain scission) . . . . . . . . . . . . . . . . .. 307 2711 Degradation from the chain ends (unzipping) /307 2712 Statistical chain degradation (random scission) /308 2713 Chain degradation through hydrolysis /312

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Table of Contents xiii

272 Reactions without chain scission. . . . . . . . . . . . . . . . . . . . .. 315 2721 Aging phenomena /315 2722 The degradation of polyvinylchloride, polyvinylidene

chloride, and polyacrylonitrile at elevated temperature /316 272 3 Reactions along the polymer chain /318 2724 Reactions at the chain end /331

The Properties of the Individual Macromolecule ..................

31 Molecular weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..

311 Polymer analogous conversion ...................... 312 Molecular weight determination .......................

3121 The end group method /337 3122 The osmotic method /341 3123 The light-scattering method /348 3124 Determination of the molecular weight through

sedimentation in the ultracentrifuge and diffusion measurements /358

3125 Molecular weight determination by viscometry /374

313 Molecular weight distribution ........................ 3131 The distribution curve /385 3132 Determination of the distribution curve by means of

fractional precipitation /389 3133 Other methods of fractionation /403 3134 Theoretical derivation of the distribution function

(Schulz-Flory distribution) /411 3135 Molecular weight averages /425

32 The form of the macromolecule (molecular shape) ..............

321 The ideal statistical coil (random coil) .................. 3211 The quantitative description of the statistical coil with

3212 the aid of random flight statistics /441 The dependence of the coil diameter .Jh2 and the coil density on the molecular weight M /445

3213 The geometric shape of the coils /447 3214 The problem of solvent streaming through the coil

(draining) /448 322 The real statistical coil ............................

3221 Space filling and energetic interaction /448 3222 Experimental determination of coil properties /450

States of Macromolecular Aggregation ........................

41 Intermolecular forces and aggregation (association) .............

332

332

332

336

385

435

438

448

484

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42 The macromolecular solution 488

421 The dissolution process. . . . . . . . . . . . . . . . . . . . . . . . . . .. 488

422 The dilute solution. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 492

423 The viscosity of dilute solutions . . . . . . . . . . . . . . . . . . . . .. 499

4231 The Einstein viscosity law for macromolecular solutions /501 4232 Viscosity changes resulting from density changes

of the coils /510

424 Concentrated solutions and gels . . . . . . . . . . . . . . . . . . . . .. 541 4241 Dependence of the viscosity on the velocity (shear)

gradient /541

43 The gel state ..................................... 543

431 Character, properties, and significance of gels. . . . . . . . . . . .. 543 4311 Plasticized polyvinylchloride as a thermo-reversible

secondary valence gel /545 4312 The mechanical properties of gels /545 4313 Characterization of gels /547 4314 The significance of gels in nature /548

432 Structure of supercritical solutions and gels .............. 548 4321 The individual coil structure model (ICS model) /548 4322 Deformation of gel and rubber /556 4323 Chain entanglement /558 4324 Incompatibility of polymer mixtures /559

44 The rubber-elastic state (viscoelasticity) .......... . . . . . . . . .. 561

441 Rubber-elasticity (viscoelasticity) of melts of macromolecular compounds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 561 4411 Rubber-elasticity and relaxation /562 4412 Thermoplastic deformation /563

442 Rubber-elasticity of cross-linked polymers .............. 564 4421 The elongation of rubber-elastic materials /567 4422 Rubber-elasticity - normal elasticity /570

45 The solid state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 572

451 The glassy state. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 573 4511 The mechanics of elastomers and glasses /577

452 The crystalline state. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 588 4521 Crystallization, chain-folding /588 4522 Morphological structures /593 4523 Spiral form of the chains (helix structure) /593 4524 Fiber structure /595 4525 Cold drawing /598 4526 Morphological structures of natural polymers /600 4527 The fiber diagram /603

453

Appendix

Table of Contents

Structure and properties in the solid state ............. . 4531 Structure and softening temperature with glassy

polymers /607 4532 Structure and properties of crystalline polymers /612 4533 The property combination: "hard and tough" /614 4534 Impact-resistant polymer blends /618 4535 Foams /622

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629

Index ............................................... 631

POLYMER CHEMISTRY