The NMR of Polymers

365 Pages·1970·11.848 MB·English

by  I. Ya. Slonim, A. N. Lyubimov (auth.)

The NMR of
Polymers
The NMR of
Polymers
LVa. Sionim
Director, Radiospectroscopy Group
Plastics Research Institute
Moscow
and
A. N. Lyubimov
Head, Radiospectroscopy Design Section
Institute of Organic Chemistry
Academy of Sciences of the USSR
Moscow
Translated from Russian by
C. Nigel Turton and Tatiana I. Turton
9?
PLENUM PRESS, NEW YORK· 1970
The Russian text, originally published by Khimiya Press in
Moscow in 1966, has been corrected by the authors for this
edition. The present translation is published under an agree
ment with Mezhdunarodnaya Kniga, the Soviet book export
agency.
THE NMR OF POLYMERS
YADERNYI MAGNITNYI REZONANS V POLIMERAKH
ftAEPHblA MArHMTHbiA PE30HAHC B nonMMEPAX
H. R- A. H.
CIIOHHM, nlOliHMOB
Library of Congress Catalog Card Number 69-12543
ISBN-13: 978-1-4684-1775-3 e-ISBN-13: 978-1-4684-1773-9
001: 10.10071978-1-4684-1773-9
© 1970 Plenum Press, New York
Softcover reprint of the hardcover 1s t edition 1970
A Division of Plenum Publishing Corporation
227 West 17th Street, New York, N. Y. 10011
All rights reserved
No part of this publication may be reproduced in any form
without written permission from the publisher
Preface to the American Edition
In the time since this book was written, the application of
NMR in the study of polymers has continued to develop rapidly.
The main trends of the work have remained as before, namely, the
study of the structure of polymers, molecular motion in them, and
chemical conversions of high-molecular-weight substances. How
ever, as a result of the refinement of experimental techniques and
development of the theory, new progress has been achieved, par
ticularly in the NMR spectroscopy of polymer solutions.
We therefore decided that it was worthwhile to provide an ad
ditionallist of literature, covering papers published in 1965, 1966,
and the beginning of 1967. By using the bibliographic directory
appended to the list, the reader can readily find references to the
latest literature for all sections of the book.
I. Ya. Slonim
A. N. Lyubimov
v
Preface to the Russian Edition
The aim of this book is mainly to answer the questions which
inevitably arise for a chemist who wishes to use NMR in his work
on polymers.
What is NMR? What is the physical nature of the phenom
enon? What are the basic quantitative rules of the processes oc
curring in a sample which is placed in a steady magnetic field and
subjected to a magnetic field of resonance frequency?
How do we determine the NMR spectrum of a polymer? How,
in general terms, is an NMR spectrometer constructed, and how do
we select suitable conditions for determining the spectrum in re
lation to the nature of the sample and the problem at hand? How
is a spectrum analyzed so as to obtain the information required?
What problems in the chemistry and physical chemistry of
polymers may be solved by means of NMR, and what are the main
results of work in this field?
The application of NMR in polymer chemistry is increasing.
The refinement of NMR spectrometers and in particular the de
velopment of high-resolution instruments which operate at ele
vated temperatures offer great new possibilities. It would obvious
ly be risky to attempt to give at the present time a critical gener
alization of all available material and a complete picture of the
state of work in this field. The authors undertook a more modest
task, namely, to give a systematic account of published work and
to clarify the main trends in the study of high polymers of NMR.
We hope that the book will be useful in this form.
The book is divided into two parts.
vii
viii PREFACE TO THE RUSSIAN EDITION
Par tOn e is theoretical and contains the physical bases of
the NMR method and the appropriate mathematical procedures. In
the opinion of the authors this material is quite necessary for
understanding methods of calculating high-resolution spectra and
for interpreting them. The presentation is quite simple and intel
ligible to a reader who has acquired the fundamentals of higher
mathematics and physics at the levels of courses given to chemists
in higher institutes of learning. Introductory information on the
theory of matrices is of necessity brief. The reader requiring
more information on this theory is referred to any book on higher
algebra.
In addition. in Part One we describe the principles of con
struction of NMR spectrometers and methods of recording and in
terpreting spectra.
Part Two of the book consists of a review of papers on
NMR of high polymers published through 1963 and the most impor
tant and interesting papers which have appeared in 1964-65.
The distribution of the material between Chapters III-VI is
arbitrary to some extent. For example, in the examination of struc
tural problems we also discuss molecular motion. Naturally, the
selection of material is also partly arbitrary; work carried out by
the authors or of interest to them is examined in greatest detail.
At the end of the book there is a bibliographic directory of
books and reviews on NMR and original work on NMR of individual
polymers.
The introduction to the book and Chapters I and II were writ
ten by A. N. Lyubimov, and Chapters III-VI by I. Ya. Slonim.
The authors consider it their pleasant duty to thank their co
workers in the Plastics Research Institute and the Central Automa
tion Laboratory, Ya. G. Urman, A. G. Konovalov, A. F. Varenik,
and V. I. Belitskaya for help in the planning of the book, and M. B.
Neiman, N. M. Pomerantsev, D. Ya. Tsvankin, E. I. Fedin, and
T. N. Khazanovich, who checked the manuscript.
Contents
. . . . . . . . . . . . . . . . . . . . . . . . .'. . . . .
Introduction 1
PART ONE
Chapter I
Physical Bases of Nuclear Magnetic Resonance. • • • • • • 11
1. Nuclear Spin and Magnetic Moment. • . • • • . • • 11
2. Behavior of an Isolated Atomic Nucleus in
Magnetic Fields. • • • . . • . • • • • • • • • • • • • • • 26
3. Nuclear Magnetic Resonance in a Real Substance 34
4. Nuclear Magnetization of a Substance . • • • • • • 53
5. Magnetic Interaction of Atomic Nuclei. • . . . • • 58
Chapter II
Recording and Interpretation of NMR Spectra. . • • • . • • 73
1. Characteristics of NMR Spectra of Liquids. . . • 73
2. Characteristics of NMR Spectra of Solids. . • • • 88
3. Nonstationary Processes. . • . • . • • • • • • • . . • 97
4. Apparatus for Observing and Recording NMR
Spectra . . . • . • . • . . • • . . • • • • • • • • . . . . • 104
5. Recording and Interpretation of Spectra. • • . • • 122
Literature Cited. . • . . . . • . • . . . • . . • • • • . . . . 144
PART TWO
Chapter III
Study of the Structure of Polymers by the NMR Method. . 149
1. Form of the Lines of NMR Spectra of Polymers 150
2. Study of Crystallinity of Polymers • . . • • . • • • 158
3. Nuclear Magnetic Resonance in Oriented
Polymers. • • . . . . • • . • . . . • . . • . • . . . . . . 172
4. Study of the Chain Structure of a Polymer 191
ix
x CONTENTS
Chapter IV
Study of Molecular Motion in Polymers by the
NMR Method. • • • • . • • • • • • • • • • • • • • • • • • • • • • • . 221
1. Effect of Molecular Motion on the Form, Width,
and Second Moment of Lines in the NMR Spec-
trum of a Polymer in Bulk. . . • • . . • . . • • • . . 221
2. NMR Relaxation Time and Molecular Motion in
Polymers. . . • . • • • . • • • • • • . • • . • • • • • • . 237
3. Comparison of Data Obtained by the NMR
Method and Other Methods. • • • • • • . . • • • • • • 247
4. Study of Molecular Motion in the System
Polymer-Low-Molecular Substance. • . . • . • . 251
Chapter V
Study of Chemical Processes in Polymers by the
NMR Method . . • • • . • . . • • • . . • • • • • • • . • . • . • • • . 261
1. Study of Polymerization . • • • • . • • • • . • . • • . 261
2. Study of Cross-Linking Processes in Polymers. 273
3. Study of the Effect of Radiation on Polymers. • . 279
4. Study of Breakdown and Other Reactions in
Polymers. . . . • . . • • • • • . • • • • • • • • • . • • • 289
Chapter VI
Use of the NMR Method for
Quantitati ve Analysis of Polymers. • • • • • • • • • • . • • . • 299
1. Determination of the Composition of Two-Phase
Systems. • • • • • • • • • • • • • • • • • . • • . • • • • . 299
2. Determination of the Composition of Copolymers 308
Bibliography. • . • • • • • • • • • . • • . • • • • • • • • • • • • • • 311
Additional Bibliography. • . . • • • • . • . . . • • • • • . • • • • 335
Subject Index to Bibliography. • • • • • • • • • • • • • • • • • • 345
Index .•.......•...•.................... 353
8
Introduction
Nuclear magnetic resonance (NMR) is one of a group of phe
nomena which constitute a field of physics known as r a d i 0 s p e c
t r 0 s cop y. The characteristic feature of these phenomena is
that in them we observe induced transitions of microparticles be
tween energy levels, which arise under definite conditions. These
transitions are accompanied by electromagnetic emission or ab
sorption in the radiofrequency range. In the case of NMR,
we are concerned with the behavior of atomic nuclei in exte rnal
magnetic fields.
Experimental data accumulated in physics show unequivocally
that many atomic nuclei have their own angular momentum and an
associated magnetic moment which characterize the magnetic
*
field of the nucleus.
I,
The vectors of the magnetic, ~, and mechanical, moments
are collinear, and are related by the equation
where 'Y is a coefficient known as the gyromagnetic ratio and is a
nuclear characteristic.
Initial attempts to explain the existence of nuclear moments
by rotation of a nucleus with mass and charge were unsuccessful.
The observed properties of nuclear moments were contradictory
to the theory based on this assumption. Thus. according to this
theory, the magnetic moment of a proton should be exactly equal to
the nuclear magneton:
en
mn=2cmp
·Some atomic nuclei also have an electric quadrupole moment, which is a measure of
the deviation of the charge distribution inside the nucleus from a spherically sym
metrical distribution.
1
2 INTRODUCTION
where .fl is the reduced Planck constant ~ = hi 2 7T); e and m pare
the charge and mass of a proton, respectively; c is the velocity of
*
light.
The magnetic moment of a proton actually measured corre
sponded to the nuclear magneton only in order of magnitude. More
over, the gyromagnetic ratios of some nuclei were even found to be
negative, which is contradictory to the theory mentioned.
According to contemporary ideas, the nature of nuclear mo
ments is more complex. In view of the fact that the source of
nuclear moments plays no part in the NMR phenomena interesting
us, here we will examine only the observed properties of nuclear
moments.
It has been established experimentally that for any atomic
nucleus the length of the vector of the intrinsic angular momentum
is always expressed by the relation
The number I, which is called the spin number, or simply the
spin of the nucleus, may be an integer, half-integer, or zero, de
pending on the type of the nucleus. The spin of the elementary par
%.
ticles which form a nucleus (protons and neutrons) equals t Ex
perimental data also make it possible to assume that the spin of
an atomic nucleus is in a certain sense a combination of the spins
of the elementary particles forming the nucleus. Thus, if the mass
wmber of the nucleus (i.e., the total number of protons and neu
trons in the nucleus) is odd, the spin is a half-integer. If the mass
number is even, while the atomic number of the nucleus (i.e., the
number of protons present in the nucleus) is odd, then the spin is
an integer. Finally, if the mass number and the atomic number of
the nucleus are even, the spin equals zero.
Even more interesting properties of nuclear moments were
observed by studying the behavior of atomic nuclei in strong steady
• In analogy with the Lande g-factor for electrons, the relation between the nuclear
... +-
moments fl and J is sometimes expressed by the equation
.... J _
h
ft=gnmn' h' so that gn-Y'mn
t Nuclei with a spin of 1/ z have no electric quadrupole moment.