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Polymer spectroscopy 1996 fawcett

Polymer Spectroscopy
Edited by

ALLAN H. FAWCETT
The Queens University of Belfast,
Belfast, Northern Ireland, UK

JOHN WILEY & SONS
Chichester • New York • Brisbane • Toronto • Singapore


Copyright © 1996 by John Wiley & Sons Ltd,
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LIST OF CONTRIBUTORS

Gordon G. Cameron
Department of Chemistry, University of Aberdeen, Meeston Walk, Old Aberdeen
AB92UE, Scotland, UK
Michelle Carey
Department of Chemistry, Imperial College of Science, Technology and Medicine,
South Kensington, London SWl'2AY, UK
Trudy G. Carswell
Chemistry Department, University of Queensland, Brisbane, QLD 4072, Australia
Francesco Ciardelli
Dipartimento di Chimica e Chimica Industriale, Universita of Pisa, Via
Risorgimento 35, 56126 Pisa, Italy
Iain G. Davidson
Department of Chemistry, University of Aberdeen, Meeston Walk, Old Aberdeen
AB9 2UE, Scotland, UK
Christine Duch
Chemistry Department, University of Wales, Swansea, Singleton Park, Swansea


SA2 8PP, Wales, UK
Allan H. Fawcett
School of Chemistry, The Queen's University of Belfast, Belfast BT95AG, Northern Ireland, UK
Adriano Fissi, CNR
Institute of Biophysics, University of Pisa, Via Risorgimento 35,56126 Pisa, Italy
Jerome Fournier
Chemistry Department, University of Wales, Swansea, Singleton Park, Swansea
SA2 8PP, Wales, UK
R. Wayne Garrett
Chemistry Department, University of Queensland, Brisbane, QLD 4072, Australia
J. G. Hamilton
School of Chemistry, The Queens University of Belfast, Belfast BT95AG,
Northern Ireland, UK


Robin K. Harris
Department of Chemistry, University of Durham, Science Laboratories, South
Road, Durham DHl 3LE, UK
James R. Hayden
Chemistry Department, University of Wales, Swansea, Singleton Park, Swansea
SA28PP,Wales,UK
Patrick J. Hendra
Department of Chemistry, University of Southampton, Highfield, Southampton
SO95NH, UK
Ian R. Herbert
Department of Chemistry, University of Durham, Science Laboratories, South
Road, Durham DHl 3LE, UK
David J. T. Hill
Chemistry Department, University of Queensland, Brisbane, QLD 4072, Australia
Oliver W. Howarth
Centre for Nuclear Magnetic Resonance, Department of Chemistry, University of
Warwick, Coventry CV4IAL, UK
Roger N. Ibbett
Department of Chemistry, University of Durham, Science Laboratories, South
Road, Durham DHl 3LE, UK
Jack L. Koenig
Department of Macromolecular Science, Case Western Reserve University, 10900
Euclid Avenue, Cleveland, OH 44106-7202, USA

W.F.Maddams,
Department of Chemistry, University of Southampton, Highfield, Southampton
SO95NH,UK
James H. O'Donnell
Chemistry Department, University of Queensland, Brisbane, QLD 4072, Australia
(Deceased)
David Phillips
Department of Chemistry, Imperial College of Science, Technology and Medicine,
South Kensington, London SW72AY, UK
Osvaldo Pieroni
Dipartimento di Chimica e Chimica Industriale, and CNR, Institute of Biophysics,
Universita di Pisa, Via Risorgimemto 35, 56126 Pisa, Italy
Peter J. Pomery
Chemistry Department, University of Queensland, Brisbane, QLD 4072, Australia


Adrian R. Rennie
Polymers and Colloids Group, Cavendish Laboratory, University of Cambridge,
Madingley Road, Cambridge CB3 OHE, UK
R. W. Richards
Department of Chemistry, University of Durham, Durham DHl 3LE, UK
J. J. Rooney
School of Chemistry, The Queen's University of Belfast, Belfast BT9 5AG,
Northern Ireland, UK

H.W.Spiess
Max-Planck-Institute
Germany

fur Polymerforschung, Postfach 3148, D-55021 Mainz,

Alan E. Tonelli
Fiber and Polymer Science Program, College of Textiles, North Carolina State
University, PO Box 8301, Raleigh, NC 27695-8301, USA
Graham Williams
Chemistry Department, University of Wales, Swansea, Singleton Park, Swansea
SA2 8PP, Wales, UK
Mark A. Whiskens
Department of Chemistry, University of Durham, Science Laboratories, South
Road, Durham DHl 3LE, UK
Catherine L. Winzor
Chemistry of Department University of Queensland, Brisbane, QLD 4072, Australia
Robert J. Young
Manchester Materials Science Centre, University of Manchester, Grosvenor
Street, Manchester Ml 7HS, UK


Index
Index terms

Links

A
AB quartet

18

acrylonitrile-furan copolymers

27

adsorbtion

242

afine deformation

183

aggregation

355

alignment (Homeotropic, planar)

282

alkylcyanobiphenyl

282

alpha (shift) effect

339

9

56

alpha (greek) process

277

alpha helix

355

amorphous polymers

276

332

anisotropies

173

235

APT (attached proton test)

11

autocorrelation function

278

azobenzene groups

351

B
Bernoullian statistics
beta (shift) effect

21
9

beta (greek) process

277

biaxial orientation

176

blends

245

57

340

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391


392

Index terms

Links

C
catalysts

33

C– –C(triple) stretch

214

CD Circular dichroism

350

chain transfer

32

charge-transfer complex participation

22

chiral macromolecules
chemical shift
chemical shift image
cis double bonds

347
2
157

159

36

Cobalt-60 gamma irradiation

263

Cole-Cole plot

290

composites

159

conformation

55

conformational data

97

conformational transitions

352

correlation times

235

COSY

221

221

84

coupling constant
cross polarization Robin

7

111

135

crosslinked systems

12

Cryogenic trapping

270

crystalline polymers

280

261

D
deformation

203

degradation

253

263

11

73

DEPT Assignment technique

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393

Index terms

Links

desorption

165

diacetylene monomers

204

dichroic difference

187

dichroic ratio

180

dielectric constant/permittivity

258

dielectric relaxation modes

279

Dielectric Relaxation Spectroscopy (DRS)

275

dienes as monomers

287

25

diffusion

162

167

diglycidyl ether of bisphenol-A (DGEBA)

121

288

domain size

125

146

double bond dyada, triads
dynamic dichroic

38
192

E
elastomers

197

electroactive

282

electron spin resonance (esr)

231

electrooptical

282

enantiomer copolymerization

41

ethylene glycol dimethacrylate

254

ethylene-vinyl acetate copolymers
excimer

253

88
374

F
Fourier transform (NMR)
Fourier transform vibration spectroscopy
fractal

8
173

257

15

free radical

231

255

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315


394

Index terms
fumarate-vinyl acetate copolymer
furan-acrylonitrile copolymers

Links
245
27

G
g value (esr)
gamma gauche effect

235

255

57

64

97

gamma rays

263

gamma relaxation

280

gels

259

311

332

glass transition temperature

142

165

240

Goldman-Shen pulse sequence

126

H
helix content

354

367

I
imaging (NMR)
INEPT assignment technique

151
72

inhomogeneities

151

interfacial

224

interferometer

177

IR

173

isotope enrichment (D)

257

30

K
Karplus

111

Kerr Constant

280

Kevlar

204

Kohlrausch-Williams-Watts

277

207

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395

Index terms

Links

L
lamellar morphology
Lewis acid effect

125
29

light scattering

297

linear response theory

278

liquid crystalline polymers

145

282

loss (dielectric)

275

283

luminescence

369

M
Magic-angle Spinning (MAS) NMR
Markov statistics

92
144
359

meso dyads

18

metallacarbenes

35

methacrylate radical

260

methylmethacrylate

254

41

8

18

55

97

molecular anisotropy

173

molecular size

331

morphology

136

Motion (of polymer)

231

Motionally-narrowed

239

multidimensional NMR

135

N
natural rubber

138

21

merocyanine

microstructure

119

161

198

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32


396

Index terms

Links

near lR

257

neutron scattering

325

nitroxide

232

NMR

7

117

135

160

281

27

103

151
NOESY NMR assignment

87

Norris-Tromsdorf region

257

nylon

128

O
optical activity

347

orientation

173

P
permittivity(dielectric)

275

phase separating mixtures

305

photophysics

369

pixel

165

poly(acrylonitrile)

19

poly(alpha amino acids)

351

poly(alpha methyl styrene)

265

poly(bisphenylurethane-2,4-hexadiyne-1,6-diol)

205

poly(butadiene)

27

poly(but-l-ene sulphone)

16

poly(isobutylene)

199

polycarbonate

167

poly(diacetylene) single crystal fibre

205

poly(dimethyl siloxane)

161

poly(2,6-dimethyl-l,4-phenylene oxide)

196

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21


397

Index terms
polyester(branched)
poly(ethyl cyanoacrylate)
poly(2-ethylhexyl methacrylate)
polyethylene

Links
9

12

15
248
9

181

184

210

212

281

polyethylene terephthalate)

145
277

182
281

189

poly(L-glutamic acid)

352

poly(2,4-hexadiyne-1,6-bis (p-toluenesulphonate))

205

poly(isoprene)

246

poly(L-lysine)

351

polymer dynamics

136

275

338

polymerization

253

poly(methacrylonitrile)

107

poly(methyl acrylate)

277

poly(methylmethacrylate)

7
165
259

10
246
260

107
254
268

poly(n-butyl isocyanate)

235

poly(norbornene)

35

43

poly(oxymethylene)

140

143

281

polypropylene

10
103

58
122

66

68

277

190
267

193
315

10

92

poly(propylene oxide)
polystyrene
polystyrene(syndiotactic)
poly(styrene block butadiene block styrene)
polysulphide

196
15

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246
373


398

Index terms

Links

poly(vinyl acetate)

243

277

poly(vinyl alochol)

104

371

poly(vinyl chloride)

105

130

poly(vinyl fluoride)

83

281

poly(vinylidene fluoride)

81

142

246

297

309

334

radical

231

255

Raman Spectroscopy

173

203

regio selectivity

18

38

40

resolution enhancement

12

Ring Opening Metathesis Polymerization (ROMP)

30

RIS (rotational isomeric state)

62

98

109

183

281
poly(vinyl methyl ether)

141

powder pattern spiess

137

prochiral face

35

Q
quasi elastic scattering

R

Rotor-synchronized MAS NMR

144

Rouse modes

338

S
SALS (small angle light scattering)

298

SANS (small angle neutron scattering)

330

semicrystalline polymers

298

semidilute

313

silica absorbent

242

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399

Index terms

Links

silicone polymer

282

simulation (esr spectrum)

266

solid polymer NMR

117

solution NMR

135

7

specular reflectance

177

spin density

157

spin label

231

spin probe

231

spin relaxation (proton)

125

spirobenzopyran

357

steroselectivity

35

stereospecific polymerization

32

strain

185

203

stress

185

203

styrene-MMA copolymers

84

substituent effects

56

surfaces

316

333

T1

119

125

T1rho(ρ)

125

T2

125

T

tacticity

15

Tactic sequence

98

tensile stress

222

thermoset (epoxy amine)

288

time-resolved measurements

184

two-dimensional IR

192

two-frequency-addressing

282

153

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153


400

Index terms

Links

U
uniaxial orientation

174

urethane-diacetylene copolymers

219

UV light

351

V
vinyl acetate copolymer
vinyl chloride copolymers
voxel

279
67
155

W
WAAS

209

Wigner rotation matrix

286

WISE NMR

141

WLF (Williams Landel Ferry)

241

Y
Young's modulus

206

Z
Zeigler-Natta polymerization

31

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INTRODUCTION TO POLYMER
SPECTROSCOPY
A. H. FAWCETT

The Queen's University of Belfast

Historically there was a difficulty in dealing with macromolecules that was simply
the realisation of their large size; the organic chemist's early painstaking methodology for isolating, studying and recognising the readily obtained small natural
product molecule did not lend itself to the examination of many natural
macromolecules such as cellulose and rubber. Such chemists, used to identifying
their substances by the melting point complemented by similar studies on the
derivatives and then the slow construction of the molecule by use of a developing
repertoire of piecemeal reactions, were slow to accept how readily high polymers
might be man-made by a simple but powerful repetitive process. Ancient practices
and evolving technology might utilise materials such as wood, leather, silk and
cotton, but the true macromolecular nature of these materials was not appreciated until about 60 years ago, and methods for exploring the large molecule and
the development of appropriate concepts for a proper scientific enquiry took time
to evolve. Spectroscopy has played a role in this process, light scattering in
particular being used to show how high molecular weights might be, and NMR
spectroscopy latterly being used to identify polymer structures. Now spectroscopy is at the heart of modern developments within polymer science, being used
not only to characterise the microstructure of the chains, but also to monitor their
dynamics, so important in determining the physical properties of interest to the
materials scientist and engineer, and to explore the interesting properties that are
being introduced in the search for special effects to be used in devices.
Two developments have given us insight into polymers at the molecular level,
the first being the spectroscopic techniques for recognising molecular components and the manner in which they are linked together, which is the topic of the
first part of this book. Of course, the analytical problem of recognising a particular polymer is less severe to the man who chose the monomer and the polymerisation process (and any plasticiser or stabiliser) than it is to a would-be emulator,
but the proper description of the microstructure of a macromolecule is as
essential to the developmental chemist (Chapter 1) as it is to his competitor. For
this purpose, NMR spectroscopy has now overtaken IR spectroscopy as the
Polymer Spectroscopy. Edited by Allan H. Fawcett
© 1996 John Wiley & Sons Ltd


analytical tool in general use. A second advance, much associated with Flory, was
the development of statistical mechanical methods. These have provided insight
into the equilibrium configurations of the isolated polymer chain and the manner
in which modest thermal energies develop elaborate configurations within the
backbones and any side chains, so that the calculations of the mean values of such
quantities as dipole moment and end-to-end distance are complex, yet focus upon
such readily visualised ideas as the potential surface for the conformations of each
pair of adjacent bonds. NMR spectroscopic quantities such as chemical shift and
coupling constant may be considered in just these terms, as Tonelli has described
for us (Chapter 2). One has only to reflect on a subject area such as liquid crystals,
where so often the description is formulated by the physicist in terms of unit cell
properties, to realise how much closer workers with polymers routinely think in
terms of molecular structure, and are able to link a certain molecular feature to an
interesting property.
Configurational elaborations are the prime characteristic of molecules rendered extremely long by the repetitive enchainment of a small number of simple
residues: Ciardelli et al. describe the manner in whch stimuli such as light may
induce changes in the structure of pendent groups and so in polymer-solvent
interactions that are amplified by the connectivity of the system to cause
profound changes in the equilibrium statistics of the single chain, and hence in its
solution properties. Indeed, a group of chains may so be led to associate
reversibly (Chapter 14). The manner in which light interacts with chromophores
in bulk polymers, located either within the standard residues or merely within
minor components such as end groups, is the subject of Phillips and Carey's
contribution (Chapter 15). There are two interrelated factors to be disentangled—the manner in which light is absorbed, whether it is retained or migrates,
and how the energy is eventually used, together with the dynamics of the moieties
involved in this process. Excimer formation, luminescence, fluorescence and
other photophysics processes are all subject to such factors as spacing constraints
and the timescales of segmental motions, which in the bulk are not merely the
property of a single molecule.
Although the physical chemistry of the chain isolated in solution is well
understood, the question of its performance within the bulk has thus become the
subject of much study. Rapid movement between adjacent conformations ceases
below the glass transition of an amorphous polymer, and in the crystalline state
packing effects become significant and restrict configurations to a very few. The
question of the location of the backbone is readily tackled: spectroscopic
techniques for studying the configurations of the polymer in amorphous and
crystalline phases within the bulk are well established; neutron scattering is
a prime, if expensive, tool for the determination of molecular dimensions and for
the study of dynamics (in a quasielastic scattering mode) and is now being
developed as a method for studying surface structures (Chapter 13). The contrast
is obtained by use of perdeuterated molecules. Light scattering is a more familiar


tool for investigating polymers; the method was introduced originally by such
luminaries as Debye, and has developed, with the availability of lasers, in the
quasielastic mode, not just for chains isolated in solution but also for gels, when
various modes of motion may be inferred from treatments of the fluctuations of
the intensity of the light scattered. The technique is now applied to studying phase
separating mixtures and events within polymers upon surfaces (Chapter 12).
Richards also covers the small angle light scattering method as used to investigate
semi-crystalline polymers.
IR and Raman spectroscopy characterise the high frequency vibrations of the
skeleton and pendent atoms of the macromolecule, and so immediately tell us
what groups are present; they have a useful analytical capacity to distinguish, for
example, a poly(methyl methacrylate) (PMMA) from a PVC or a polyolefin.
Vibration modes extend over several simple oscillators (such as bonds and bond
angles); in the crystalline state they reflect the arrangement adopted within the
unit cell, from which IR bands and Raman shifts follow conventional symmetryrelated selection rules. They may be used to measure crystallinity, as such. In the
amorphous state conformational elaborations are not averaged out on the
timescale of the vibration. Observed bands are thus composite and relatively
broad, and although they may indicate whether in a rubber a double bond is cis or
trans, and may measure the presence of methyl groups in low density polyethylene, band frequencies are not as sensitive as solution NMR spectroscopy to
microstructure details extending over several residues. The fine structure observed in the shifts of linear polymers is itself a topic of careful consideration, as
Tonelli and Howarth et al. have described (Chapters 2 and 3). The conformational origin within vinyl polymers of the patterns displayed in 13 C shifts is now
well established, and provides the best source of information on tacticity and
residue sequence, so that one might attempt to discriminate between mechanisms
for propagation, such as those of the Bernoullian and Markov type, those
involving charge-transfer complexes, and mechanisms involving catalysts derived from metal complexes (Chapter 1). Once one has evidence on the reaction
mechanism, one may proceed to the design of new and better catalysts.
Like vibration spectroscopy, NMR in the solid state, made feasible by the cross
polarisation-magic angle spinning dipole decoupling method, is similarly rather
insensitive to microstructural issues within the crystalline and amorphous states,
but interesting results may be obtained when carefully chosen systems are
compared: Harris presents the cases of the 4/1 helix of syndiotactic polypropylene
and the 3/1 helix of isotactic polypropylene, the former clearly displaying
sensitivity to the helix structure through the gamma-gauche effect so that internal
and external methylenes are distinguished, and the latter displaying some
sensitivity to the helix sense of the neighbouring chains (Chapter 4). The solid
state NMR method is capable also of sensing inhomogeneities such as arise from
microcrystals within a homopolymer such as polyethylene, and within blends of
two different and only partly compatible polymers (Chapters 4 and 5), an area


that is similarly tractable by modern two-dimensional methods that are being
developed within IR spectroscopy (Chapter 7). Both chemical shift and IR
vibration frequency of one chain are sensitive to the nature of the neighbouring
chains, particularly if an interaction such as a hydrogen bond is possible. The
timescale of magnetic polarisation decay is capable of being linked to the size of
the inhomogeneities.
Mobility as measured by proton or carbon NMR relaxation times is a property
of matter, including polymeric materials and any permeated liquid, that may be
sensed by a scanning technique and displayed in an image form, usually in two
dimensions. Koenig surveys for us the various applications he has made, the
images providing an interesting comparison with the more conventional light
and electron microscope viewing methods (Chapter 6).
Vibration spectroscopy is sensitive, as Hendra and Maddams describe
(Chapter 7), to such factors as anisotropy within such samples as uniaxially
drawn rods and biaxially drawn films, allowing their properties to be optimised
from an understanding of the molecular process. Such well established use of IR
spectroscopy is now being succeeded by dynamic dichroic methods, to reveal
how the backbones and side chains separately respond to imposed cyclic stresses.
This provides a fascinating account of the manner in which different modes of
motion come into play. A development of Raman spectroscopy described by
Young is the response of certain vibrations in the spectrum to a progressive strain
imposed upon the material, a technique that may exploit recent instrumental
developments such as charge coupled device cameras and the confocal Raman
microscope (Chapter 8). For a composite material, the technique allows us to
answer a question such as the manner of the distribution of strain along
a polyaramid fibre within a matrix that initially bears the imposed stress; the
particular interest is the length of fibre required to take up the strain.
The timescale of the response of a polymer to a stimulus ranges from the high
frequencies of IR radiation through to the low frequencies or long time scales of
diffusion of the whole molecule by the reptation mechanism, a process that is
amenable to study by dielectric relaxation spectroscopy, as in studies on cispolyisoprene by Adachi. The dielectric response is present only from polar units,
and is governed by the location of the dipoles, whether within side chains or
backbones, in the geometry of the dipole itself and the geometry and flexibility of
the neighbouring segments. For the chain in solution, simple and satisfactory
accounts are available in these terms, and only in special cases do the dipoles
themselves mutually organise to control the response. For the bulk material,
whether in crystalline, amorphous or liquid crystalline form, cooperations between chains may be significant. For example, the alpha relaxation of crystalline
polyethylene is a progression of a kink in one chain within a crystalline region, as
computer simulations have modelled: it is the linear all-trans neighbours that
define the tube within which the single chain performs (Chapter 11). Distributions
of correlation times may be extremely wide in an amorphous material, but how


much this derives from variations in local conformations and orientations of the
dipole within the chain in question, and how much from intra-chain influences
(which may themselves have a response) is, as they say, a very good question! The
same issues arise when studying the dynamic mechanical behaviour of polymers,
a method closer to the concerns of the polymer engineers. Perhaps the developing
power of NMR spectroscopy to measure correlation functions and the magnitude of the orientational jump and to identify the pathways of the motion will
help provide an answer to these questions (Chapter 5). As Spiess describes, the
NMR method might measure the angle of displacement, as well as its frequency,
for poly(oxymethylene), displaying helical jump dynamics. Two-dimensional and
three-dimensional experiments are now being performed to measure motions and
to determine order within oriented solids (Chapter 5). The use of a paramagnetic
probe coupled with electron spin resonance (ESR) monitoring provides information, within the timescale range of 10"3 s to 10"7 s, of a complementary nature,
for by sensing the mode of rotation of the radical within the polymeric matrix, it
measures the behaviour of the "holes", the packets of free volume, that facilitate
the movements of the chains and play a vital role in the glass transition, Tg,
phenomena. Locating the radical on the chain or at its end allows one to sense the
extra degree of freedom at a polymer chain end (Chapter 9).
The ESR technique in this book is applied to a second issue, monitoring the
radicals actually responsible for a polymerisation of pure monomer plus a certain
amount of crosslinker, the interest lying in the changes that take place to create
a new regime when the gel effect operates, during which termination reactions are
much retarded by the immobilisation of the radicals, as they are also in the final
period, when the development of a glass is the cause of onset of a third regime
(Chapter 10). O'Donnell's work monitors the radicals by ESR and the unreacted
groups by near-IR spectroscopy, to reveal new insight into the kinetics during
these periods. This study of the chemistry of free radical polymerisation is
succeeded by a discussion of an equally important topic, as far as industrial use is
concerned, the detailed chemistry of degradation by ionising radiation of polystyrene and poly(methyl methacrylate): following such training, O'Donnell's previous students helped develop microlithography.
This book records the principal lectures given at a Conference in Grasmere
organised by the Macro Group. The proceedings of two of the previous conferences with this subject area and sponsorship have also been published [1, 2] and
provide a useful indication of the developments that have occurred over recent
years in the practice and value of polymer spectroscopy.

REFERENCES
[1] KJ. Ivin (Ed.), Structural Studies of Macromolecules by Spectroscopic Methods, John
Wiley & Sons, London, 1976.
[2] A.H. Fawcett, Br. Polym. /., 1987,219,97 and following papers.


Contents

List of Contributors .............................................................

xiii

Introduction to Polymer Spectroscopy ..........................

1

1. NMR Characterisation of Macromolecules in
Solution .......................................................................

7

1.1

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

7

1.2

Branched Molecules: Polyethylene and a
Polyester System ..........................................................

9

1.3

The Microstructure of Linear Chains ............................

15

1.4

The Participation of a Charge-Transfer Complex in
a Free Radical Polymerization Reaction ......................

22

1.5

The Polymerization of Dienes ......................................

25

1.6

Ring-Opening-Metathesis Polymerizations ..................

30

1.6.1

Stereoselectivity in ROMP .........................

32

1.6.2

Distribution of trans Double Bonds in
High cis Poly(Norbornene) .........................

36

1.6.3

Regioselectivity in ROMP ..........................

41

1.6.4

Direct Observation of Tacticity ...................

45

References ...................................................................

52

2. Conformation: the Connection between the NMR
Spectra and the Microstructures of Polymers .........

55

1.7

2.1
2.2

Introduction ...................................................................
13

Substituent Effects on C Chemical Shifts ..................
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55
56

v


vi

Contents
2.3
2.4

2.5

γ-Gauche Effect Method of Predicting NMR
Chemical Shifts .............................................................

60

Applications of γ-Gauche Effect Analysis of
Polymer Microstructures ...............................................

64

2.4.1

Polypropylene (PP) ....................................

64

2.4.2

Propylene-Vinyl Chloride Copolymers
(P-VC) ........................................................

67

2.4.3

Poly(Propylene Oxide) (PPO) ....................

68

2.4.4

Poly(Vinylidene Fluoride) (PVF2) ................

81

NMR Spectroscopy as a Means to Probe Polymer
Conformations ..............................................................

84

2.5.1

Styrene-Methyl Methacrylate
Copolymers (S-MM) ...................................

84

Ethylene-Vinyl Acetate (E-VAc)
Copolymers ................................................

88

NMR Observation of Rigid Polymer
Conformations ..............................................................

92

References ...................................................................

93

3. ‘Model-Free’ RIS Statistical Weight Parameters
from 13C NMR Data .....................................................

97

2.5.2
2.6
2.7

3.1

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

3.2

Methods ........................................................................ 100

3.3

Some Calculation Details ............................................. 101

3.4

Individual Polymers ...................................................... 102

3.5

The Calculated RIS Parameters .................................. 109

3.6

β-Gauche Effects .......................................................... 111

3.7

Coupling Constants ...................................................... 111

3.8

Characteristic Ratios .................................................... 113

3.9

Conclusions .................................................................. 114
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97


Contents

vii

3.10

Acknowledgement ........................................................ 115

3.11

References ................................................................... 115

4. NMR Studies of Solid Polymers ................................ 117
4.1

Introduction ................................................................... 117

4.2

The Techniques ............................................................ 118

4.3

High-Resolution Carbon-13 NMR of Polymers ............ 121

4.4

Proton Spin Relaxation ................................................. 125

4.5

Discrimination in Carbon-13 Spectra ........................... 128

4.6

Spectra of Abundant Spins ........................................... 131

4.7

Conclusion .................................................................... 132

4.8

Acknowledgements ...................................................... 132

4.9

References ................................................................... 133

5. Multidimensional Solid-State NMR of Polymers ...... 135
5.1

Introduction ................................................................... 135

5.2

Multidimensional Solid-State NMR Spectra ................. 137

5.3

Examples ...................................................................... 138
5.3.1

Increase of Spectral Resolution ................. 138

5.3.2

Separated Local Field NMR ....................... 140

5.3.3

Wideline Separation Experiments .............. 141

5.3.4

2D and 3D Exchange NMR ........................ 142

5.3.5

Chain Alignment from 2D and 3D NMR ...... 144

5.3.6

Domain Sizes from Spin Diffusion
Experiments ............................................... 146

5.3.7

Spatially Resolved Solid State NMR .......... 146

5.4

Conclusion .................................................................... 148

5.5

Acknowledgements ...................................................... 149

5.6

References ................................................................... 149
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viii

Contents

6. NMR Imaging of Polymers ......................................... 151
6.1

6.2

Introduction ................................................................... 151
6.1.1

Basis of NMR Imaging ............................... 151

6.1.2

Relaxation Parameters in NMR Imaging .... 153

6.1.3

Resolution in NMR Imaging ....................... 155

6.1.4

Utility of NMRI ............................................ 155

6.1.5

Image Processing ...................................... 156

Advanced Imaging Techniques .................................... 156
6.2.1

6.3

Chemical Shift Imaging .............................. 156

Applications of NMRI to Polymers ................................ 159
6.3.1

Detection of Voids in Composites .............. 159

6.3.2

Detection of Nonuniform Dispersion of
Filler ........................................................... 161

6.3.3

NMRI of Physical Aging ............................. 161

6.3.4

NMRI Studies of Diffusion in Polymers ...... 162

6.3.5

Desorption of Liquids from Polymers ......... 165

6.3.6

Multicomponent Diffusion as Studied by
NMRI ......................................................... 167

6.3.7

Absorption-Desorption Cycling of
Liquids in Polymers .................................... 169

6.4

Acknowledgements ...................................................... 171

6.5

References ................................................................... 171

7. Fourier Transform Infrared and Raman
Spectroscopies in the Study of Polymer
Orientation .................................................................. 173
7.1

Introduction ................................................................... 173
7.1.1

The Basis of Orientation Measurements
by Infrared Spectroscopy ........................... 174

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Contents
7.1.2
7.2

7.3

ix

The Basis of Orientation Measurements
by Raman Spectroscopy ............................ 176

........................................................................................ 177
7.2.1

Experimental Techniques on Static
Samples ..................................................... 177

7.2.2

Infrared Spectroscopic Studies on
Oriented Polymers ..................................... 180

7.2.3

Raman Spectroscopic Studies on
Oriented Polymers ..................................... 182

Time Resolved Measurements .................................... 185
7.3.1

The Response of a Viscoelastic System
to Sinusoidal Stress ................................... 185

7.3.2

Experimental .............................................. 187

7.3.3

Some Examples of Dynamic Linear
Dichroic Infrared Studies ............................ 192

7.4

Elastomers Under Stress ............................................. 198

7.5

Conclusion .................................................................... 200

7.6

References ................................................................... 201

8. Deformation Studies of Polymers using Raman
Spectroscopy ............................................................. 203
8.1

8.2

8.3

Introduction ................................................................... 203
8.1.1

Polydiacetylene Single Crystals ................. 204

8.1.2

Extension of the Technique to Other
Materials .................................................... 206

High-Performance Polymer Fibres ............................... 206
8.2.1

Aromatic Polyamide Fibres ........................ 206

8.2.2

Polyethylene Fibres ................................... 210

Isotropic Polymers ........................................................ 214
8.3.1

Urethane-Diacetylene Copolymers ............ 214

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