Dielectric and Related Molecular Processes Volume 3

272 Pages·1977·20.649 MB·English

A Specialist Periodical Report
Dielectric and Related Molecular
Processes
Volume 3
Reviews of Recent Developments up to December 1976
Senior Reporter
Ma nsel Dav ies, Edward Davies Chemical Laboratories,
University College of Wales, Aberys t wyth
Reporters
M. Evans, University College of Wales, Aberystwyth
E. Jakusek, University of Wrocfaw, Poland
J. Janik, Institute of Nuclear Physics, Krakow, Poland
G. Jones, Courtaulds, Spondon Research Centre, Derby
B. F. Levine, Bell Telephone Laboratories, New Jersey, USA
T. J. Lewis, University College of North Wales, Bangor
R. Pethig, University College of North Wales, Bangor
L. Sobczyk, University of Wrocfaw, Poland
V. Wada, University of Tokyo, Japan
The Chemical Society
Burlington House, London W 1 V OBN
1
ISBN: 0 85186 525 9
ISSN; 0305-974X
Library of Congress Catalog Card No. 72-83457
Copyright 0 1977
The Chemical Society
All Rights Reserved
No part of this book may be reproduced or transmitted
in any form or by any means-graphic, electronic,
including photocopying, recording, taping or
inf ormation storage and retrieval systems-without
written permission from The Chemical Society
Typeset in Press Roman by
Preface Limited, Salisbury, Wiltshire
Printed in Great Britain by
Whitstable Litho L td., Whitstable, Kent
ii
Preface
My first concern is to offer thanks to the contributors, all of whom have given
generously of their time to provide worthy items for this volume. The quality of
the volume is a direct reflection of their co-operation.
Clearly, this particular series should help to answer the question: what is new
in dielectric studies? A reading of these chapters will at least provide some major
indications. Most of the developments are, naturally, extensions of earlier
aspects where new insights have been provided. Some aspects included here lie
outside the scope of dielectric studies per se: this could be true of Chapter 1
and, more particularly, of Chapter 2. Nevertheless, the themes of these
contributions relate closely to molecular features in dielectric studies and they
are of immediate concern to those interested in the study of molecular motion
whose representation is being largely recast as a result of the procedures these
chapters discuss.
Chapter 3 provides a summary of advances which have transformed the status
of molecular hyperpolarizabilities from the position where data were available
for a few, usually simple, molecules to one where their systematic evaluation is
possible and their relation to chemical bond conditions can be analysed.
Polymeric materials have, if only for technological reasons, been long studied
by dielectric methods. It is, therefore, a privilege to be able to offer the reader
the account in Chapter 5, where it is seen that older qualitative patterns are
replaced by a clear quantitative approach which, in many ways, provides a very
substantial advance - the more to be welcomed as it relates polymer behaviour
to basic aspects of the organic solid-lattice state. Chapter 7 llkewise provides an
unified approach to the total electrical response in the solid state in terms of
essential structural elements and mobile electron or ionic charges. These two
chapters are such as to promote a coherent appreciation of tutherto somewhat
unco-ordinated molecular model representations. There are obvious links
between their contents and those of Chapters 4, 6, and 8.
In this sense one can perhaps justifiably claim that dielectric studies
contribute not only to the analysis of details of molecular behaviour but are also
helping to build a unified framework for material science.
A berystwy th Manse1 Davies
June 19 77
...
111

Contents
Chapter 1 Correlation and Memory Function Analysis of Molecular
Motion in Fluids 1
By M. W. Evans
1 Introduction 1
2 General Formalism in Classical Mechanics: Memory
Functions 5
3 M and J Diffusion Models and RayleighlRaman Scattering 14
4 Higher Order Truncations of the Mori Continued Fraction 24
5 Laser Light Scattering and Related Studies 39
6 Recent Relevant Papers 41
7 Summary 44
Chapter 2 Quasielastic Neutron Scattering Studies of Molecular
Reorientations 45
By J. A. Jdnik
1 Introduction 45
2 Information on the Phenomenonological Approach to
Molecular Reorientational Relaxation 46
3 Information concerning the Neutron Experimental
Technique 49
4 QNS Studies of Stochastic NH3 Reorientation in
[Ni(NH3)6 ] (C104)2 Crystals 51
5 QNS Studies of Fast Reorientations in a Liquid Crystal 58
6 QNS Studies of Uniaxial Molecular Rotation in Phase I1 of
65
(CH3)3CN02
7 Other QNS Studies of Stochastic Reorientations 69
8 Conclusions 72
Chapter 3 Studies of Molecular Characteristics and Interactions using
Hyperpolarizabilities as a Probe 73
By B. F. Levine
1 Introduction 73
2 Experimental Technique 74
3 Hyperpolarizability Contributions 75
4 Local Field Factors 77
V
vi Con tents
5 Comparison with Other Techniques 78
6 Nonconjugated Bond Additivity 79
Unsubst ituted Alkanes 79
Substituted Hydrocarbons 80
Methyl Iodide and Methylene Iodide 80
7 Conjugated US. N on conjugat ed H y perpolarizab ili ties 81
8 Substituted Benzene Derivatives 82
9 Origin of p": Benzene Ring-Substituent Charge Transfer 86
10 Intramolecular Donor-Acceptor Charge Transfer 88
11 Charge-transferC omplexes 93
Experiments on (Pyridine + 12), (Pyridine t ICl), and
(4-Aminopyridine t 12) 93
12 A Polypeptide a-Helix: PBLG 97
Low-field Limit 97
Time Response 97
Electric Field Saturation 97
13 Molecular Interactions in Associating Liquid Mixtures 99
Local Fields and Molecular Correlations 99
Weakly Associating Liquids 100
Strongly Associating Liquids 106
Chapter 4 Some Dielectric Studies of Molecular Association 108
By E. Jakusekand L. Sobczyk
1 Introduction 108
2 Dipole Moments of Molecular Complexes 108
Complexes with Hydrogen Bonds 108
Electron Donor-Accept or Complexes 110
The oret ic a1 A spec t s 112
Solvent Effects 114
3 Dielectric Relaxation Studies 117
Theoretical lntroduction 117
Dielectric Relaxation in Associated Liquids 121
Alcohols 121
Phenols 128
Carboxylic Acids 129
Dielectric Relaxation of Molecular Complexes 130
Hydrogen-bond Complexes 130
Theore tical Treatment 136
Electron Donor--A ccept or Complexes 140
Chapter 5 Dielectric and Related Properties of Polymers in the Solid
State 143
By Y. Wada
Contents vii
1 Introduction 143
2 Dielectric Relaxation above the Glass Temperature 144
Dielectric Increment and Molecular Structure 144
Relaxation Times 145
Other Subjects 146
3 Dielectric Relaxation Due to Motion of Side-chains 146
Motion of Flexible Side-chains as a Whole 146
Motion of the End Group in the Side-chain 147
Motion of the Rigid Side-chain 148
4 Motion of Backbone Chains in the Crystalline Phase and the
Amorphous Phase below the Glass Temperature 149
General 149
Pol yet hylene 15 1
Poly(e t hylene Terephthalate) 152
Poly(viny1idene Fluoride) 152
Poly ox yme thylene 153
5 Dielectric Loss of Polymers at Very Low Temperatures 154
6 Dielectric Loss at the Microwave and Far Infrared Region 156
General 156
Polyethylene 157
Poly te t rafluoroe thylene 158
Other Polymers 159
7 Higher-order Effects in Dielectric Phenomena 159
Electrostriction Effect 159
Second-order Susceptibility 160
8 Piezoelectricity and Pyroelectricity 16 1
General 161
Piezoelectricity due to Internal Strain (Mechanism A) 162
Piezo- and Pyro-electricity due to the
Change of Spontaneous Polarization
(Mechanism B) 164
Piezo- and Pyro-electricity due to Embedded Charges and
Heterogeneity (Mechanism C) 167
0t her Problems 168
9 0 ther Topics 168
Effects of Various Factors upon Dielectric Properties 168
Effects of Ionic Conduction on the Complex Permittivity 168
Effects of Impurities 169
Dielectric Anisotropy 169
Dielectric Relaxations of Synthetic Polymers 170
Pol yamides 170
Polymers containing Imido Groups 170
Polvsiloxanes 170
viii Contents
Polymers containing Aromatic Groups in the Main Chain 171
Ion-containing Polymers 17 1
Other Polymers 171
Thin Films 172
Copolymers and Polymer Blends 172
Dielectric Relaxations of Polypeptides and Biopolymers 173
Experimental Methods 174
Chapter 6 Dielectric Studies of Adsorbed Molecules 176
By G. Jones
1 Introduction 176
2 Experimental Techniques and Procedures 176
3 Experimental Results 180
4 Conclusions 185
Chapter 7 The Dielectric Behaviour of Non-crystalline Solids 186
By T. J. Lewis
1 Introduction 186
2 Equivalent Represent at ions of the Phenomena 189
3 A Model for the Dielectric Response 19 1
Localized states and the Origins of Dipoles 193
Elementary Polarization Processes 196
The Total Dielectric Response 20 1
4 Special Cases 203
Random Range Hopping 203
Random-energy Activated Hopping 206
Spectral Analysis of Dielectric Functions 209
Explanation of the J(t) and u(u)L aws 21 1
5 Conclusions 216
Chapter 8 Some Dielectric and Electronic Properties of Biomacro-
molecules 219
By R. Pethig
1 Introduction 219
2 Dielectric Properties 220
The a-A mino-acid s 220
Polypeptide Chains and Protein Molecules 222
The Peptide Unit Dipole Moment 224
Molecular Permittivity of Protein Molecules 228
The ‘Oildrop’ Model for Protein Molecules 230
Dielectric Disoersions of Protein Solutions 313