Polymer chemistry

The Practical Approach in Chemistry Series
SERIES EDITORS

L. M. Harwood
Department of Chemistry
University of Reading

C. J. Moody
Department of Chemistry
University of Exeter

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The Practical Approach in Chemistry Series
Organocopper reagents
Edited by Richard J. K. Taylor
Macrocycle synthesis
Edited by David Parker
High-pressure techniques in chemistry and physics
Edited by Wilfried B. Holzapfel and Neil S. Isaacs
Preparation of alkenes
Edited by Jonathan M. J. Williams
Transition metals in organic synthesis
Edited By Susan E. Gibson (née Thomas)
Matrix-isolation techniques
Ian R. Dunkin
Lewis acid reagents
Edited by Hisashi Yamamoto
Organozinc acid reagents

Edited by Paul Knochel and Philip Jones
Amino acid derivatives
Edited by Graham C. Barrett
Asymmetric oxidation reactions
Edited by Tsutomu Katsuki
Nitrogen, oxygen and sulfur ylide chemistry
Edited by J. Stephen Clark
Organophosphorus reagents
Edited by Patrick J. Murphy
Polymer chemistry
Edited by Fred J. Davis

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Polymer Chemistry
A Practical Approach
Edited by

FRED J . DAVIS
The School of Chemistry,
The University of Reading, UK

1
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To my wife Jacqueline, my children Charlie, William, Gracie, and
Briony, and to my late mother Mrs Josephine P. Davis

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Preface
It is some time since Laurence Harwood suggested to me the idea of this
volume of the Practical Approach in Organic Chemistry series, and whilst
initially I could see the value of such a contribution, as the subsequent delay
in production testifies, I have had some difficulty in transposing this topic to a
relatively small text. There are many scientific publications devoted entirely
to the area of polymer synthesis, with tens of thousand pages devoted to the
topic in the scientific literature every year I have focused on those aspects of
the topic which I find interesting, and consequently there are certainly many
omissions. I hope, however, that the examples I have included will give a
flavour of what can be achieved (generally without recourse to highly specialized equipment) in terms of the development of novel macromolecular

systems. As with all the volumes in the Practical Approach Series, this book
aims to provide a detailed and accessible laboratory guide suitable for those
new to the area of polymer synthesis. The protocols contained within this
manuscript provide information about solvent purification, equipment and
reaction conditions, and list some potential problems and hazards. The latter
point is particularly important and in most instances I have referred to the
manufacturers’ safety data sheet (MSDS, which companies such as Merck
and Aldrich provide on-line); however, often these vary in detail from sourceto-source and from time-to-time, and of course local rules always must take
precedance.
I am particularly indebted to the contributors to this work for their excellent efforts and prompt responses to my requests. I am also grateful to my
postgraduate students, particularly Dario Castiglione and Vidhu Mahendra
for checking some of the experimental details, and to my colleague at
Reading Dr Wayne Hayes for his constant enthusiasm and advice.
Fred J. Davis
Reading
December 2003

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Contents
Contributors

xiii

Abbreviations

xvii

1. Polymer characterization

1

Ian L. Hosier, Alun S. Vaughan, Geoffrey R. Mitchell, Jintana
Siripitayananon, and Fred J. Davis
1. Introduction
2. Synthetic routes to polymers
3. Molecular weight determination
4. Composition and microstructure
5. Optical microscopy
6. Electron microscopy
7. Analytical microscopy
8. Scanning probe microscopy
9. Thermal analysis
10. Molecular relaxation spectroscopy
11. X-ray and neutron scattering methods
12. Conclusions
References

2. General procedures in chain-growth
polymerization

1
2
4

7
9
11
14
16
18
21
24
32
33

43

Najib Aragrag, Dario C. Castiglione, Paul R. Davies,
Fred J. Davis, and Sangdil I. Patel
1. Introduction
2. Free-radical chain polymerization
3. Anionic polymerization
4. Ring-opening polymerizations initiated by anionic reagents
5. Coordination polymers
6. Conclusions
References

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43
44
67
83
90

95
95


Contents

3. Controlled/‘living’ polymerization methods

99

Wayne Hayes and Steve Rannard
99

1. Introduction
2. Covalent ‘living’ polymerization: group transfer
polymerization
3. Controlled free-radical polymerizations mediated by nitroxides
4. Controlled free-radical polymerizations: atom transfer free-radical
polymerizations (ATRP) and aqueous ATRP
References

4. Step-growth polymerization—basics and
development of new materials

101
109
116
123

126

Zhiqun He, Eric A. Whale, and Fred J. Davis
2. The synthesis of an aromatic polyamide

126
127

3. Preparation of a main-chain liquid crystalline poly(ester ether)
with a flexible side-chain

130

4. Non-periodic crystallization from a side-chain bearing
copolyester

135

1. Introduction

5. A comparison of melt polymerization of an aromatic di-acid
containing an ethyleneglycol spacer with polymerization in
a solvent and dispersion in an inorganic medium
References

5. The formation of cyclic oligomers during
step-growth polymerization

138
143

145

Abderrazak Ben Haida, Philip Hodge, and
Howard M. Colquhoun
1. Introduction

145

2. Synthesis and extraction of cyclic oligomers of
poly(ether ketone)

146

3. Synthesis of some sulfone-linked paracyclophanes
from macrocyclic thioethers
4. Summary
References

x

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152
156
156


Contents

6. The synthesis of conducting polymers based

on heterocyclic compounds

158

David J. Walton, Fred J. Davis, and Philip J. Langley
158
159
163
178
181
186
186

1. Introduction
2. Electrochemical synthesis
3. Synthesis of polypyrrole
4. Synthesis of polyaniline
5. Synthesis of polythiophene
6. Conclusions
References

7. Some examples of dendrimer synthesis

188

Donald A. Tomalia
1. Introduction
2. Excess reagent method
3. Protection–deprotection method
References

8. New methodologies in the preparation of
imprinted polymers

188
190
193
199

201

Cameron Alexander, Nicole Kirsch, and Michael Whitcombe
1. Introduction
2. Sacrificial spacer approach
3. Preparation of bacteria-imprinted polymers
References

9. Liquid crystalline polymers

201
203
210
214
215

Sangdil I. Patel, Fred J. Davis, Philip M. S. Roberts,
Craig D. Hasson, David Lacey, Alan W. Hall, Andreas Greve,
and Heino Finkelmann
2. Synthesis of an acrylate-based liquid crystal polymer

215
217

3. The hydrosilylation reaction: a useful procedure for the
preparation of a variety of side-chain polymers

225

1. Introduction

xi

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Contents
4. Photochemical preparation of liquid crystalline elastomers
with a memory of the aligned cholesteric phase
5. Defining permanent memory of macroscopic global alignment
in liquid crystal elastomers
6. Summary
References

Index

229
234
244
244
246

xii

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Contributors
cameron alexander
School of Pharmacy and Biomedical Sciences, University of Portsmouth, White
Swan Road, Portsmouth, PO1 2DT, UK
najib aragrag
The Department of Chemistry, The University of Reading, Whiteknights, Reading,
Berkshire, RG6 6AD, UK
abderrazak ben haida
Department of Chemistry, University of Manchester, Oxford Road, Manchester,
M13 9PL, UK
dario c. castiliglione
The Department of Chemistry, The University of Reading, Whiteknights, Reading,
Berkshire RG6 6AD, UK
howard colquhoun
The Department of Chemistry, The University of Reading, Whiteknights, Reading,
Berkshire RG6 6AD, UK
paul r. davies
School of Chemistry, The University of Reading, Whiteknights, Reading, Berkshire
RG6 6AD, UK
fred j. davis
School of Chemistry, The University of Reading, Whiteknights, Reading, Berkshire
RG6 6AD, UK
heino finkelmann
Institut für Makromol eculare Chemie, Universität Freiburg, Stefan-Meier-Strasse

31, Freiburg D-79104, Germany
andreas greve
Institut für Makromol eculare Chemie, Universitat Freiburg, Stefan-Meier-Strasse
31, Freiburg D-79104, Germany
alan w. hall
The Department of Chemistry, The University of Hull, Kingston-upon-Hull,
Cottingham Road, Hull HU6 7RX, UK
craig d. hasson
JJ Thomson Physical Laboratory, PO Box 220, Whiteknights, Reading RG6
6AF, UK

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Contributors

wayne hayes
The Department of Chemistry, The University of Reading, Whiteknights,
Reading, Berkshire RG6 6AD, UK
zhiqun he
Institute of Optoelectronic Technology, Beijing Jiaotong University, Beijing
100044, China
philip hodge
Department of Chemistry, University of Manchester, Oxford Road, Manchester,
M13 9PL, UK
ian l. hosier
School of Electronics and Computer Science, University of Southampton, SO17
1BJ, UK
nicole kirsch
Bioorganic and Biophysical Chemistry Laboratory, Department of Chemistry

and Biomedical Sciences, University of Kalmar, SE-391 82 Kalmar,
Sweden
geoffrey r. mitchell
JJ Thomson Physical Laboratory, PO Box 220, Whiteknights, Reading RG6
6AF, UK
philip j. langley
School of Chemistry, The University of Reading, Whiteknights, Reading,
Berkshire RG6 6AD, UK
sangdil i. patel
School of Chemistry, The University of Reading, Whiteknights, Reading,
Berkshire RG6 6AD, UK
philip m. s. roberts
JJ Thomson Physical Laboratory, PO Box 220, Whiteknights, Reading RG6
6AF, UK
david lacey
The Department of Chemistry, The University of Hull, Kingston-upon-Hull,
Cottingham Road, Hull HU6 7RX, UK
steve rannard
Unilever Research Port Sunlight Laboratory, Quarry Road East, Bebington,
Wirral, CH63 3JW, UK
jintana sirpitayananon
Biopolymers Research Unit, Department of Chemistry, Faculty of Science,
Chiang Mai University, 50200, Thailand

xiv

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Contributors

donald a. tomalia
Michigan Molecular Institute, 1910 West St. Andrews Road, Midland,
MI 48640–2696, USA
alun s. vaughan
School of Electronics and Computer Science, University of Southampton, SO17
1BJ, UK
david j. walton
School of Science and the Environment, Coventry University, Priory Street,
Coventry CV1 5FB, UK
eric a. whale
JRA Technology Ltd, JRA House, Taylors Close, Marlow, Buckinghamshire
SL7 1PR, UK
michael j. whitcombe
Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4
7UA, UK

xv

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Abbreviations
AFM
AIBN

ATRP
BHT
CCD
CFI
CLSM
DBE
DIC
DMF
DMSO
DMTA
DP
DSC
DTA
DVB
EELS
EGDMA
FTIR+A28
GPC
GTP
HPLC
IR
LCST
LED
LSCE
LSM
MALDI-TOF
MAO
MBPI
MDSC
MHTBO

MIP
MOPS
NIPA
NMP
NMR

atomic force microscopy
2,2Ј-Azobisisobutyronitrile
atom transfer free-radical polymerization
2,6-Di-t-butylphenol
charge coupled device
contact force imaging
confocal laser scanning microscopy
dibutyl ether
differential interference contrast
dimethylformamide
dimethylsulfoxide
dynamic mechanical thermal analysis
degree of polymerization
differential scanning calorimetry
differential thermal analysis
divinylbenzene
electron energy loss spectroscopy
ethyleneglycol dimethacrylate
Fourier transform infra-red.
gel permeation chromatography
group transfer polymerization
high performance liquid chromatography
infra-red
lower critical solution temperature

Light emitting diode
Liquid single crystalline elastomer
Laser scanning microscope
matrix-assisted laser desorption ionization—time of
flight
methylaluminoxane
methylene bis(phenly isocynate)
Modulated DSC
1-methyl-4-hydroxymethyl-2,6,7-trioxabicyclo[2,2,2]-octane
Molecularly imprinted polymers
(3-[N]-morpholino)propylsulfonic acid
N-Isopropyl acrylamide
N-methyl pyrrolidone
nuclear magnetic resonance

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Abbreviations

PAA
PAMAM
PEEK
PEK
PET
PHB
PMMA
PPV
PPTS
PTFE

PVC
PVF2
RAFT
ROMP
SCE
SEC
SEM
SPM
STEM
STM
TASHF2
TBABB
TEM
TEMPO
THF
TLC
UV–Vis

poly(allylamine)
poly(amidoamine)
poly(ether ether ketone)
poly(ether ketone)
Polyethylene terephthalate
poly(hydroxybutyrate)
polymethylmethacrylate
poly(phenylenevinylene)
Pyridine-p-toluenesulfonate
poly(tetrafluoroethylene)
polyvinlychloride
poly(vinylidene fluoride)

reversible addition fragmentation chain transfer
ring-opening metathesis polymerization
standard calomel electrode
size exclusion chromatography (ϭGPC)
scanning electron microscopy
scanning probe microscopy
scanning transmission electron microscopy
scanning tunnelling microscopy
tris(dimethylamino) sulfonium bifluoride
tetra-n-butyl ammonium bibenzoate
transmission electro microscopy
2,2,6,6-Tetramethylpiperidinyl-1-oxy
tetrahydrofuran
thin layer chromatography
Ultraviolet–Visible

xviii

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1
Polymer characterization
I A N L . H O S I E R , A L U N S . VAU G H A N , G E O F F R E Y R . M I T C H E L L ,
J I N TA N A S I R I P I TAYA N A N O N , a n d F R E D J . D AV I S

1. Introduction
Polymer science is, of course, driven by the desire to produce new materials
for new applications. The success of materials such as polyethylene,
polypropylene, and polystyrene is such that these materials are manufactured

on a huge scale and are indeed ubiquitous. There is still a massive drive to
understand these materials and improve their properties in order to meet
material requirements; however, increasingly polymers are being applied to a
wide range of problems, and certainly in terms of developing new materials
there is much more emphasis on control. Such control can be control of
molecular weight, for example, the production of polymers with a highly
narrow molecular weight distribution by anionic polymerization.1 The control of polymer architecture extends from block copolymers to other novel
architectures such as ladder polymers and dendrimers (see Chapter 7).2,3
Cyclic systems can also be prepared4,5 (see Chapter 5), usually these are
lower molecular weight systems, although these also might be expected to be
the natural consequence of step-growth polymerization at high conversion.6
Polymers are used in a wide range of applications, as coatings, as adhesives,
as engineering and structural materials, for packaging, and for clothing to
name a few. A key feature of the success and versatility of these materials is
that it is possible to build in properties by careful design of the (largely)
organic molecules from which the chains are built up. For example, rigid
aromatic molecules can be used to make high-strength fibres, the most highprofile example of this being Kevlar®; rigid molecules of this type are often
made by simple step-growth polymerization7 and offer particular synthetic
challenges as outlined in Chapter 4. There is now an increasing demand for
highly specialized materials for use in for example optical and electronic
applications and polymers have been singled out as having particular potential
in this regard. For example, there is considerable interest in the development
of polymers with targeted optical properties such as second-order optical nonlinearity,8 and in conducting polymers (see Chapter 6) as electrode materials,9

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I. L. Hosier et al.

as a route towards supercapacitors10 and as electroluminescent materials.11

Polymeric materials can also be used as an electrolyte in the design of compact batteries.12
A particular feature of polymers is the possibility of linking together
separate chains to form networks. Such cross-links can be introduced by
copolymerization of a monofunctional monomer such as styrene with a
difunctional monomer such as divinylbenzene.13 If the degree of cross-linking
is high, the resulting network becomes rather rigid and intractable. A particularly important feature of this is that the network produced interacts only
slightly with solvents; as a consequence the material can be readily separated
from organic solutions. Such materials are increasingly important in a range
of areas: these include polymer-supported reactions, such as those in peptide
synthesis,14 combinatorial chemistry,15 and catalysis;16 and molecular separation where imprinted polymers offer a powerful route to highly specific
separation.17 Examples of routes to imprinted polymers are included in
Chapter 8. Lightly cross-linked materials have also attracted considerable
interest, since the potential for reversible deformation introduces the possibility of a number of novel properties. Such materials include solvent swollen
systems (wet gels)18,19 and liquid crystalline elastomers;20 the former
systems are often rather simple to prepare, while the latter may be formed
from quite complex monomers21 (as outlined in Chapter 9).

2. Synthetic routes to polymers
With the vast commercial importance of polymers it is perhaps not surprising
that there have been huge developments in synthetic methodology. The scope
of the field is such that it is impossible to provide a comprehensive review of
all these developments here, but a few examples might serve to illustrate the
area. Free-radical polymerization remains a popular synthetic method, but
even within the simplicity of this system there have been major developments,
for example, the use of supercritical CO2 as a solvent22 has huge potential. The
development of polymer-supported reagents has necessitated a tailoring of
suspension polymerizations,13,23 to suit particular needs, for example, to produce macroporous resins, i.e. resins which have a well-defined structure even
in the dry state. Emulsion polymerizations have even been undertaken in
space24 to produce extremely uniform 10 ␮m spheres. Perhaps the most exciting development in the area of free-radical polymer chemistry is the introduction of control into free-radical polymerization; initially Moad25 and later
others26 have developed a way of controlling free-radical polymerizations

using stable nitroxide radicals.27 Atom Transfer Free Radical Polymerization
(ATRP)28 is a more recent29 analogous method involving stable radical intermediates. A particularly interesting feature of this latter technique is its adaptation to hydrophilic monomers in aqueous systems, thus providing living
polymers with the ablity to tolerate the presence of water.30
2

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1: Polymer characterization

The development of ATRP has supplemented rather than superseded anionic
polymers in terms of control of polymer structure; anionic polymerization is
still the method of choice for preparing polymers with narrow molecular
weight distribution and controlled structures. This is largely because the way in
which polymeric chains may be produced that do not undergo termination is
well understood.31 There is, however, clearly a complex relationship between
the solvent, the monomer, and the counterions present and a number of techniques such as ligated anionic polymerization have developed, in this case to
ensure the growing chains are living.32 Block copolymers are particularly
important,33 for example, triblock copolymers may act as thermoplastic elastomers. The styrene–butadiene–styrene copolymer is commercially important,
but other systems include liquid crystalline thermoplastic elastomers.34 Starshaped polymers can be made by coupling the anionic chain ends with another
reactive unit35 (e.g. SiCl4); alternatively polymers with functional end groups
can be made by reacting the anion with simple molecules such as CO2 to form
an acid terminated chain.36 Other popular methods of producing living polymers include cationic polymerization37 and group-transfer polymerization.38,39
Organometallic chemistry has played an important role in improving
synthetic methodology in polymer science,40 given the success of classical
Ziegler–Natta catalytic systems,41,42 it might have been thought that at least for
bulk polymers the synthetic problems had been largely solved. However, the
development of metallocene catalysts43 has clearly shown that this is not the
case.44 The application of these catalysts to systems such as polyethylene and
polypropylene has proved of immense importance, allowing the formation of

new materials45 such as a form of polypropylene, which acts as a thermoplastic
elastomer.46 Of course, metallocenes are not the only inorganic polymerization
catalysts under investigation47 and this is proving a particularly fruitful area for
organometallic chemists. Another well-known organometallic-catalysed polymerization is the ring-opening metathesis polymerization (ROMP).48,49 One
particularly attractive feature of this is that the catalysts (often rutheniumbased)50 are not only highly active but also compatible with most functional
groups and easy to use.51 ROMP has found application in a number of areas,
but a particularly interesting one is the preparation of polyacetylene by a
precursor route referred to as the ‘Durham route’.52
In the organometallic examples cited above, polymerization occurs by a
chain-growth mechanism. Increasingly, highly efficient organometallic coupling reactions such as the Stille reaction,53 the Suzuki reaction,54,55 and others56
are being used for C–C bond formation in polymeric reactions. These
polycondensations have been used particularly to form highly conjugated
aromatic polymers, for example, the Suzuki reaction can be used to form
polyphenylene.57 There are various organometallic routes to form polythiophenes.58,59 These are particularly useful for unsymmetrical thiophenes since
they provide far greater control of the regiochemistry than electrochemical or
simple chemical oxidation.
3

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I. L. Hosier et al.

This book is largely concerned with polymer synthesis, and in the following
chapters a range of both common and more specialized synthetic methods
used to produce macromolecular systems is given. However, it must be noted
that polymers are unlike simple low molecular weight materials in that they
are not built-up from a single structure, but rather a mixture of similar materials differing, for example, in the number of monomer units attached to the
chain, or the stereochemistry around a stereogenic carbon atom. Thus, characterization is often something of a statistical exercise. In addition, because
of the huge interest in polymers as materials, often more detailed information

about properties such as orientation, thermal characteristics, and morphology
are required. In the following sections some of the methods used to characterize
polymers are described.

3. Molecular weight determination
It is important that the molecular weight characteristics of polymers can be
accurately determined.60 Of course, the precise molecular weight determined
will depend on the technique used, thus techniques that rely on the measurement of colligative properties, such as osmotic pressure, count the number of
molecules in solution and, therefore, give the number average molecular
weight Mn (Eqn (1)), while other techniques, most notably, light scattering
provide an average value based on the weight fractions of molecules of a given
mass, to give the weight average molecular mass Mw (Eqn (2)). A simple and
commonly used technique for assessing the molecular weight of a polymer is
viscometry. In this technique, the time is measured for a dilute solution of
polymer to flow through a capillary. Through measuring the times at various
polymer concentrations and comparing with the time obtained for the neat
solvent, it is possible to obtain a value for the intrinsic viscosity (or limiting
viscosity number) [␩], which can be related to the molecular weight using the
Mark–Houwink–Sakurada relationship (Eqn (3)); where M is the viscosity
average molecular weight (eqn (4)) and K and a are constants. Interestingly,
the value for a is determined directly by polymer–solvent interactions, for
example, in a theta solvent61 a is 0.5, for rod-like polymers the value can be
close to 1.0; thus, like gel permeation chromatography (GPC) the measured
molecular weight is related to the hydrodynamic volume of the molecules62.
Mn ϭ

͚
͚

(1)

Mn ϭ

͚
͚

(2)

ϱ
i ϭ 0 Ni Mi
ϱ
i ϭ 0 Ni

ϱ
2
i ϭ 0 Ni Mi
ϱ
i ϭ 0 Ni M i

4

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1: Polymer characterization

[␩] ϭ KMa

΄M

n

ϭ

͚
͚

ϱ
1ϩa
i ϭ 0 Ni Mi
ϱ
i ϭ 0 Ni Mi

(3)

΅

1/a

(4)

There is a range of techniques used to determine the molecular weight,
including the two cited above,63,64 but the most common method is GPC
(or size-exclusion chromatography, SEC).65,66 This chromatographic technique is based upon size-exclusion phenomena and enables the separation and
assessment of polydisperse systems, such as polymers and multi-component
biological samples.67 In this method, polymers are separated by virtue of their
hydrodynamic volume. The technique involves passing a solution of the polymer through a column packed with a porous solid phase (often polystyrene
cross-linked with divinylbenzene); small molecules can access these pores
rather more easily than larger molecules, as a consequence, these larger
molecules are eluted first. The technique does not give absolute values, but

rather gives relative ones; and therefore requires calibration with a series of
polymers of known molecular weight. Since the technique relies on the size of
the polymer in solution, both the solvent and the type of polymer are important. Thus data obtained for polystyrene in chloroform does not exactly match
data for polystyrene dissolved in tetra hydrofuran (THF). Similarly a sample
of poly(methyl methacrylate) in THF should not strictly be compared with
polystyrene standards. Of course, when synthesizing novel polymers it is not
possible to have matching standards, and considerable effort has been spent
finding solutions to this problem. One solution that is particularly popular
is the use of GPC in conjunction with a viscosity detector, a method known
as universal calibration.68 This technique makes use of a broadly linear relationship between the elution volume and the product of the intrinsic viscosity
and molecular weight. More recently GPC systems fitted with light scattering
detectors have become more popular.69 One particularly important feature
of this method is that it provides a good indication of the distribution
of molecular weights within the sample. Figures 1.1 and 1.2 illustrate this. The
former shows traces obtained from first- and second-generation dendrimer
samples,70 which are essentially monodisperse by Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) (in fact the GPC has insufficient resolution to provide an accurate picture of the molecular weight
distribution in these samples). Figure 1.2, in contrast, shows the molecular
weight distribution obtained from an attempt to form a styrene–acrylate
diblock copolymer using anionic polymerization (see Chapter 2). Not only is
the polydispersity index rather large (at 2.96), but also the shape of the curve
is not what might be expected from a homogeneous sample; clearly there has
been some problem in the preparation here.
5

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I. L. Hosier et al.
150

100

50

0
0

2000

4000
Mol. wt.

6000

8000

Fig. 1.1 GPC data obtained from polyaromatic dendrimers possessing a repetitive amide–
ester coupling sequence.

1.5

dw /log M

1.0

0.5

0
100

1000

10 000

1 00 000

Mol. wt.
Fig. 1.2 GPC data obtained from an attempt to form a styrene–acrylate diblock copolymer
using anionic polymerization. Both the polydispersity index (2.96) and the shape of the curve
suggest that the desired homogeneous product has not been formed.

MALDI-TOF71,72 mass spectral analysis is becoming increasingly important
as a method for the determination of molecular weights of synthetic polymers,
since in comparison to traditional methods (such as GPC), the results can be
obtained in a few minutes. In the simplest terms, the macromolecule is dispersed in a UV-absorbing matrix, and becomes volatilized when subjected to a
pulse of laser energy; the volatile particles are then ionized and subsequently
6

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