Cyclic polymers 2ed 2002 semlyen

CYCLIC POLYMERS


CYCLIC POLYMERS
(Second edition)
Edited by

J. ANTHONY SEMLYEN
University of York, U.K.

KLUWER ACADEMIC PUBLISHERS
NEW YORK, BOSTON, DORDRECHT, LONDON, MOSCOW


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CONTENTS
Preface

vii

Contributors

ix

Contributors Biographies

xiii

1
2
3
4
5
6

Introduction: Cyclic Polymers - the first 40 years
by J Anthony Semlyen, University of York, UK

1

Circular DNA

by Alexander V Vologodskii, New York University, USA

47

Cyclic Peptides
by John S Davies, University of Wales, Swansea, UK

85

Cyclic Oligosaccharides and Polysaccharides
by Shinichi Kitamura, Kyoto Prefectural University, Japan

125

Cyclic Polysiloxanes
by Stephen J Clarson, University of Cincinnati, USA

161

Cyclic Oligomers of Polycarbonates and Polyesters
by Daniel J Brunelle, GE Corporate Research and Development,
Schenectady, NY, USA

185

7

Large Crown Ethers, Cyclic Polyethers and Cyclic Block Copolyethers
by Colin Booth and Colin Price, University of Manchester, UK
229

8

Large Cyclic Esters and Ether-Esters
by Barry R Wood and S Caroline Hamilton, University of York, UK

271

Cyclomer Technology for High Performance Polymers
by Yong Ding and Allan S Hay, McGill University, Canada

307

Organic Cyclic Polymers
by Jacques Roovers, National Research Council, Canada

347

9
10
11

Neutron Scattering and Nuclear Magnetic Resonance Investigations of
Cyclic Polymers
by Peter C Griffiths, Cardiff University, UK
385
v


vi

12

13

Rotaxanes
by Harry W Gibson and Eric J Mahan, Virginia Polytechnic Institute
and State University, USA

415

Oligomeric and Polymeric Catenanes
by David A Leigh and Richard A Smith, University of Warwick, UK

561

14

Cyclic Inorganic Oligomers and Polymers
by Ionel Haiduc, Universitatea “Babes-Bolyai”, Cluj-Napoca, Romania 601

15

Cyclisation and the Formation, Structure and Properties of Polymer
Networks
by Robert F T Stepto and David J R Taylor, Manchester Materials
Science Centre, UK

16

699

Theoretical Aspects of Cyclic Polymers: Effects of Excluded Volume
Interactions
by Mustapha Benmouna, Institut de Physique et Chimie, Tlemcen,
Algeria and Ulrich Maschke, Université des Sciences et Technologies
de Lille, France

741


PREFACE

The first edition of “Cyclic Polymers” was published by Elsevier Applied
Science Publishers in 1986. It consisted often chapters reviewing the advances
that had been made in a new area of Polymer Science, where macromolecules
are based on large ring molecules rather than long chain molecules. There have
been important developments in the subject since then and this second edition of
“Cyclic Polymers” describes many of them in sixteen chapters dealing with
both synthetic and biological cyclic polymers.

In this second edition, some of the developments in cyclic polymer chemistry
over the past forty years are outlined in Chapter 1 and fundamental differences
between the properties of large ring molecules and long chain molecules are
discussed. In the following three chapters, the importance of cyclic structures in
biological macromolecular science is strikingly demonstrated by detailed

reviews of circular DNA, cyclic peptides and cyclic oligosaccharides and
polysaccharides. The preparation and properties of synthetic cyclic polymers
are covered in a series of chapters on cyclic polysiloxanes, large cyclic ethers

and ether-esters and other organic cyclic polymers. The importance of ringopening polymerization reactions to produce commercially valuable linear
polymers is emphasised in chapters on cyclic polycarbonates and cyclic

polyesters and on cyclic oligomers used to prepare high performance polymers.
Cyclic inorganic oligomers and polymers are described in a separate chapter. A
fundamental difference between large ring and long chain molecules is the
ability of the rings to form catenanes and rotaxanes and advances in both these
are described in separate chapters in this book. Two techniques that have been
found to be particularly useful for investigating synthetic cyclic polymers are
neutron scattering and nuclear magnetic resonance spectroscopy and a chapter is
devoted to outlining the applicability of both these methods. Another chapter
describes the role of cyclization in network formation. Finally, theoretical
aspects of cyclic polymer properties are reviewed in the last chapter of the book.
Two aspects of the subject of large ring molecules and cyclic polymers are
especially noteworthy. The first is its multidisciplinary nature, so that cyclic
polymers may be based on organic, inorganic or biological macromolecules and
subjects such as chemistry, physics, biology, materials science, engineering and
computer science are all involved. The second aspect results from the unique
topology of large ring molecules, which has been exploited so effectively by
nature (for example with circular DNA, which supercoils, catenates and forms
permanent knots in different natural living systems).

vii


viii

A most encouraging feature of this new, rapidly developing subject of cyclic
polymers has been the world-wide cooperation it has engendered. The editor of
this book alone has had the privilege of working with over 150 coworkers and

coauthors drawn from five continents. The authors contributing to this book
come from Algeria, Canada, England, France, Japan, Roumania, the United
States of America and Wales. Scientific research is one activity where cooperation rather than competition can result not only in greater material
achievement but also it can enhance international understanding.

The editor of this book would like to thank all the authors who have contributed
to it so effectively, as well as his coworkers at York, Dr Barry Wood and Dr
Caroline Hamilton, for their dedicated help in its final preparation.

With more and more large ring molecules and cyclic polymers being prepared,
characterised and investigated year by year in biological as well as synthetic
macromolecular systems, the future of the subject of cyclic polymers seems
well assured as we advance into the twentyfirst century.

J Anthony Semlyen

University of York 1999


CONTRIBUTORS
Chapter 1

Dr J A Semlyen
Department of Chemistry
University of York
York YO10 5DD
UK

Chapter 2

Professor Alexander Vologodskii
New York University
Department of Chemistry
New York
NY 10003
USA

Chapter 3

Dr John S Davies
University College Swansea
Department of Chemistry
Singleton Park
Swansea
W Glamorgan SA2 8PP

Wales
Chapter 4

Professor Shinichi Kitamara
Kyoto Prefectural University
Department of Agricultural Chemistry
606 Shimogamo
Kyoto
Japan

Chapter 5

Dr Stephen J Clarson
College of Engineering

644 Baldwin Hall
University of Cincinnati
OH 45221-0018
USA

ix


x

Chapter 6

Dr Daniel J Brunelle
GE Corporate Research & Development
General Electric Company
Bldg CEB, Room 130
PO Box 8
Schnectady
NY 12301
US

Chapter 7

Dr Colin Booth and Professor Colin Price
Department of Chemistry
University of Manchester
Oxford Road
Manchester
M13 9PL
UK

Chapter 8

Dr Barry R Wood and Dr S Caroline Hamilton
Department of Chemistry
University of York
York YO 10 5DD
UK

Chapter 9

Professor Allan S Hay and Dr Yong Ding
Department of Chemistry
McGill University
801 Sherbrook St W
Montreal
PQ H3A 2K6
Canada

Chapter 10

Professor Jacques Roovers
Institute for Environmental Chemistry
National Research Council of Canada
Ottawa K1A 0R6
Canada

Chapter 11

Dr Peter C Griffiths

School of Chemistry and Applied Chemistry
University of Wales Cardiff
PO Box 912
Cardiff CF1 3TB
Wales


xi

Chapter 12

Professor Harry W Gibson and Dr Eric J Mahan

Department of Chemistry
Virginia Polytechnic Institute and State University
Blacksburg
VA 24061-0212
USA
Chapter 13

Dr David A Leigh and Mr Richard Smith
Department of Chemistry
University of Warwick
Coventry
CV4 7AL
UK

Chapter 14

Professor Ionel Haiduc

Facultatea de Chimie
Universitatea “Babes-Bolyai”
RO-3400
Cluj-Napoca
Roumania

Chapter 15

Professor R F T Stepto and Dr David J R Taylor
Manchester Materials Science Centre
University of Manchester & UMIST
Grosvenor Street
Manchester
M1 7HS
UK

Chapter 16

Professor Ulrich Maschke
Laboratoire de Chimie Macromoleculaire
UA-CNRS No 351
Université des Sciences et Technologies de Lille
F-59655 Villeneuve d’ Ascq Cedex
France

Professor Mustapha Benmouna
University Aboubakr Belkaid
Institute of Physics
Bel Horizon BP119
13000 Tlemcen

Algeria


Contributors Biographies
Authors are listed in the order in which they appear in
the book
J Anthony Semlyen was a Gibbs Scholar, Salters Scholar and Domus
Senior Scholar at Merton College, Oxford until 1962 and a Research
Lecturer at Christ Church, Oxford in 1963 and 1967. He obtained his
MA, BSc and DPhil degrees at Oxford under the supervision of Dr
Courtenay S G Phillips. From 1964 to 1966, he was a Fulbright Scholar
with Professor Paul J Flory at Stanford University, California. Since
1967, he has been at the University of York. He has edited Cyclic
Polymers (Elsevier Applied Science, 1986), co-edited Siloxane Polymers
(Prentice Hall, 1993) with Dr Stephen J Clarson and edited Large Ring
Molecules (John Wiley & Sons, 1996). His research interests are large
ring molecules and cyclic polymers and he has published research papers,
reviews and books on these topics with the active collaboration of over
150 co-workers and co-authors drawn from five continents
Alexander Vologodskii received his PhD in Molecular Biophysics at
Moscow Physical Technical Institute in 1975. He spent the next 16 years
in the Institute of Molecular Genetics, Moscow. In 1985 he received the
higher Russian scientific degree, Doctor of Science, at Moscow
University. He was a visiting scientist at University of California at
Berkeley in 1992-1993 and now is Research Professor in the Department
of Chemistry at New York University. His research interests include
conformational properties of nucleic acids, particularly properties of
circular DNA molecules. He authored the book Topology and Physics of
Circular DNA (1992) and more than 70 research papers.

John S Davies received his BSc and PhD degrees from the University of
Wales, Swansea, before post-doctoral work with John C Sheehan at MIT,
Cambridge Massachusetts. He returned to Swansea as junior lecturer in
1964, joining the research team of Professor Cedric Hassall on peptide
antibiotics and general peptidomimetic work. This led to setting up his
own research group on the synthesis/modifications of cyclic peptides and
cyclodepsipeptides, carbohydrate derivatives on amino acids, and an
interest in the chiral analysis of peptides. He has reviewed annually for a
number of years, the literature on cyclopeptides and cyclodepsipeptides
for the Royal Society of Chemistry’s Specialist Periodical Reports on
Amino Acids, Peptides and Proteins. He is currently the Senior Editor of
xiii


xiv
this Specialist Periodical Report, and Senior Lecturer in the Department
of Chemistry at Swansea.
Shinichi Kitamura received his PhD in Agricultural Chemistry from
Kyoto University in 1984. From 1985 to 1987 he was a Postdoctoral
Fellow at Yale University with Professor Julian M Sturtevant. He is now
Lecturer in Chemistry of Biological Macromolecules at Kyoto Prefectural
University. His research interests include bioactive carbohydrates,
protein-carbohydrate interactions, and biochemical applications of
calorimetry.
Stephen J Clarson is a Yorkshireman by birth but currently resides in the
Cincinnati area with his wife, their two daughters, four Himalayan
Persians and two Mini Lops. He obtained his DPhil in Chemistry at the
University of York, England in 1985 where he studied with Dr Tony

Semlyen. He then spent the summer at the Institute of Macromolecular

Chemistry, Prague before taking up a postdoctoral appointment with
Professor James Mark. In the spring of 1988 he joined the faculty of the
Department of Materials Science and Engineering at the University of
Cincinnati and is currently Assistant Dean for Educational Development
in the College of Engineering. Dr Clarson has received numerous awards
for his teaching including the Neil Wandmacher Excellence in Teaching
Award in 1993 for ‘Most Outstanding Teacher in the College of
Engineering’, the TEXNIKOI Award in 1992 for ‘Outstanding Teaching
and Service to the College of Engineering’ and the Engineering Tribunal
Award, for the ‘Outstanding Teacher of the Quarter’, Spring Term, 1992
and Spring Term, 1995. Dr Clarson has also published over one hundred
technical articles and co-authored the text ‘Siloxane Polymers’ with Dr
Tony Semylen, which was published in 1993. Due for publication in
1999 is the text ‘Silicones and Silicone-Modified Materials’. The
research carried out in his group has led to a number of inventions and he
holds three US patents. His current scientific research interests include
polymer synthesis, organosilicon chemistry, cardiovascular biomaterials
and plasma polymerization.
Daniel J Brunelle received a BS degree from Emory University in 1970.
He received his MS and PhD degrees from The John Hopkins University
in 1972 and 1974. He then carried out postdoctoral research on total
synthesis and synthetic methodology with Professor E J Corey at Harvard
University for two years. After joining GE Corporate Research and
Development in 1977, he began work on a number of organic and
polymer-chemistry problems. Specific areas of interest include synthesis
and ring-opening polymerization of cyclic oligomers, high temperature
phase transfer catalysis, mechanisms of catalysis, and new methods of
polymer formation, with special emphasis on polycarbonates, and
polyetherimides. He is an inventor on over 75 patents, has published
more than 70 research papers, and was the editor of the volume “Ring

Opening Polymerization,” published in 1993.


xv
Colin Booth completed his PhD in Chemistry under the direction of
Professor Geoffrey Gee at the University of Manchester in 1956. After

working with R L Scott at UCLA he spent four years with Shell Chemical
Co,
Synthetic Rubber Division, California, before returning to
Manchester as Research Fellow, subsequently to join the teaching staff.
His present position is Reader in Polymer Science. He was editor, with
Colin Price of Volume 1 (Polymer Characterisation) and 2 (Polymer
Properties) of Comprehensive Polymer Science (1989), reflecting his
lifelong interest in this area. His present research interests include the
aqueous solution properties of block copolyethers (including the gel
state), particularly the effect of block and chain architecture, and the solid
state properties of uniform cyclic oligo(oxyethylene)s (large unsubstituted
crown ethers) and of cyclic poly(oxyethylene)s.
Colin Price obtained his PhD in Chemistry from the University of
Manchester in 1964. He then joined the teaching staff at Manchester
where he is now Professor of Polymer Chemistry and Head of the
Department of Chemistry. He has published some 200 papers on polymer

synthesis, characterisation and properties. He is the joint editor of
Volumes 1 and 2 of Comprehensive Polymer Science. For his work on

the microstructure, supramolecular structure and phase behaviour of block
copolymers in bulk and solution, and for studies on rubber elasticity, he
received the 1991 RSC Award for Macromolecules and Polymers. His

present extensive programme of research on copolymers is carried out in
collaboration with other members of the Manchester Polymer Centre, and
with groups in industry and other universities, both in the UK and abroad.
He is also engaged in research on new routes to aqueous polymer
dispersions including water borne zirconium ionomers.
Barry R Wood graduated in 1986 with a BSc (Hons) degree in Applied
Chemistry from Thames Polytechnic (now the University of Greenwich).
He obtained an MSc degree in Polymer Science at North London
Polytechnic (now the University of North London) and a PhD degree

from Brunel University in 1990 working with Professor Michael Folkes
on electrically conducting colloidal dispersed gold-polymer composites.
He has spent the last nine years as a research fellow at the University of
York working with Dr J A Semlyen preparing and studying large cyclic
esters and ether-esters.
S Caroline Hamilton gained her first degree in Chemistry at the
University of York and an MSc with distinction in Materials Technology
from Napier University in Edinburgh. She spent six months at BNFL,
Springfields in the solid oxide fuel cell group. She obtained her DPhil
degree at the University of York, where she investigated large ring esters
and ether-esters under the supervision of Dr Tony Semlyen. Her hobbies
include playing field hockey and computers. With Dr Barry Wood, she
runs a part-time computer business (“Ecky Thump Computers”).
Allan S Hay was born in Edmonton, Alberta, Canada. Dr Hay received

a BSc and MSc in Chemistry from the University of Alberta (1950,
1952). In 1955 he received his PhD in Organic Chemistry from the
University of Illinois and then joined the staff of the GE Research

xvi
Laboratory in Schenectady, NY. In 1956 he discovered a new method of
polymerization, “polymerization by oxidative coupling” which afforded
high molecular weight poly(phenylene oxide)s by direct catalytic

oxidation of phenols at room temperature. This led to the development of
GE’s
and
thermoplastic resins. These polymers today are
manufactured by several companies worldwide with annual sales above
$1 billion per year. In 1968 he became manager of the Chemical

Laboratory in the Research and Development Center of GE. In 1980 he
was appointed to the position of Research and Development Manager,
Chemical Laboratories where he directed the work of 220 scientists and
engineers engaged in exploratory chemistry, process chemistry, chemical
engineering, polymer physics and engineering, electrochemistry,
biotechnology, and electronic materials. In September 1987, Dr Hay
accepted the GE/NSERC Industrial Research Chair of Polymer Chemistry
at McGill University. Research on oxidative coupling chemistry has
continued, however, the major focus of the research has been: (1),
synthesis of amorphous, thermooxidatively stable polymers with very
high glass transition temperatures which remain soluble and processable;
(2), the development of novel methods for crosslinking these soluble
polymers to make them insoluble, which makes them attractive as
materials for use in the aerospace and electronic industries; (3), synthesis
of novel cyclic precursors to some of these high performance polymers,
which potentially makes them attractive as high temperature adhesives,
coatings, and as matrix resins for advanced composites. Dr Hay was
elected a Fellow of the Royal Society of London in 1981 and received the

Society of Plastics Engineers International Award in 1975. In 1971 he
was elected a Coolidge Fellow of General Electric. In 1984 he received
the Achievement Award of the Industrial Research Institute and in 1985
was made a Chemical Pioneer of the American Institute of Chemists. He
received the Carothers Award in 1985. In 1987 he was awarded an
honorary DSc degree from his alma mater, the University of Alberta. In
1992 he was made an Honorary Professor, Dalian University of Science
and Technology, Dalian, China. In 1997 he was awarded the Tomlinson
Chair in Chemistry. He is the author of more than 250 publications and
patents.
Yong Ding is a polymer scientist at Innovative Membrane Systems,
Praxair Inc, Norwood, MA. He obtained his PhD degree in Polymer

Chemistry with Professor Allan S Hay from McGill University. Then he
moved to the University of Arizona, working with Professor H K HallJr
as a postdoctoral fellow. His research activities include the synthesis,
characterization and application of polymers, and oligomers.
Jacques Roovers received his PhD in Polymer Chemistry from the
University of Louvain with G Smets (1962). After postdoctoral work
with S Bywater in Ottawa and at the University of Louvain, he joined the
National Research Council in Canada in 1966. In 1977-1978, he took a
sabbatical with W W Graessley at Northwestern University. He did work
on anionic polymerization and is interested in the use of anionic
polymerization for the synthesis of model polymers with long-chain
architectural features. Emphasis is placed on the relation between the
large-scale structure of polymers and its effect on their dilute solution


xvii
properties and melt theology. He is presently also adjunct professor at the

University of Athens.
Peter Griffiths obtained his BSc(Hons) degree in Chemistry from the
University College of North Wales in 1988. He then moved to Bristol
and under the guidance of Professor T Cosgrove, undertook his PhD
degree in the area of polymer diffusion. After postdoctoral periods in
Bristol and then at the Royal Institute of Technology, Stockholm working
with Professor P Stilbs, he took up his present position in Cardiff in 1985.
His research interests include polymer solutions, polymer-surfactant
interactions and the structure and dynamics of adsorbed polymer layers.
Harry W Gibson was born in Syracuse, NY, USA and grew up in the
Adirondack Mountains of northern New York State, close to the Canadian
border and ca 60 miles from Montreal. He received his BS (1962, with
distinction) and PhD (1966) degrees in Chemistry from Clarkson
University where his thesis under the direction of Professor Frank D Popp
was based on alkaloid syntheses. From 1965-66 he was a postdoctoral
research associate of Professor Ernest L Eliel at the University of Notre
Dame (IN), where he carried out stereochemical studies, primarily on
acyclic molecules. From 1966-69 he was employed as a research chemist
at Union Carbide Corporation in Tarrytown, NY, where he did research
on uses of formic acid and carried out kinetic and mechanistic studies of
reactions of alcohols with epoxides. From 1969-1984 he advanced up the
technical ladder to Senior Scientist at Xerox Corporation in Webster, NY
and was involved in studies of liquid crystals, triboelectric charging,
photoconduction and dark conduction and the synthesis of materials for
use in these technologies. In 1984 he joined Signal Corporation in Des
Plaines, IL, which later merged to become Allied Signal, as Senior
Research Scientist; there he was concerned with polymers for printed
wiring boards and membranes. In 1986 he assumed his present position
as Professor of Chemistry at VPI&SU. Professor Gibson has published
more than 275 original research papers, chapters and reviews, is listed as

inventor on 32 US patents and has delivered more man 145 invited
lectures worldwide. Currently his research interests include rotaxanes,
polyrotaxanes, hyperbranched and dendritic polymers, self assembly
processes, liquid crystalline materials and “living” radical
polymerizations. During his 12 years in academia Professor Gibson has
supported and supervised the research of 26 undergraduates, 12 PhD, 8
MS graduates and 16 postdoctoral fellows in his laboratories. Currently 1
undergraduate, 3 PhD students and 2 postdoctoral fellows work under his
direction.

David Leigh carried out his PhD studies on novel macrocyclic
trichothecenes in the research group of J Fraser Stoddart at the University
of Sheffield from 1984-1987. He then spent two years investigating
carbohydrate-protein interactions as a Research Associate with David
Bundle at the National Research Council of Canada (NRC) laboratories in
Ottawa before returning to the UK to a Lectureship at the University of
Manchester Institute of Science and Technology (UMIST) in 1989. In
1996 he was promoted directly to Reader and in October 1998 he

simultaneously took up the Chair in Synthetic Chemistry and an EPSRC


xviii
Advanced Research Fellowship in the Centre for Supramolecular and
Macromolecular Chemistry at the University of Warwick. His research
interests include novel molecular architectures and their applications in
materials.
Richard A Smith obtained his BSc(Hons) degree in Chemistry from the
University of York in 1996. He men joined the research group of
Professor David Leigh at the University of Manchester Institute of

Science and Technology (UMIST) to begin his PhD on developing a
synthetic route towards a “true” polycatenane ([n]catenane). In 1998 he
moved to the University of Warwick with Professor Leigh to complete his
final year.
Ionel Haiduc is Professor at “Babes-Bolyai” University, in Cluj-Napoca,
Roumania. He obtained his PhD in Moscow with Professor K A

Andrianov with a thesis in Organosilicon Chemistry, was a Fulbright
Postdoctoral Fellow with Professor Henry Gilman at Iowa State
University (1966-1968) and with Professor R Bruce King at the
University of Georgia, Athens, Georgia (1971-1972). He was Visiting
Professor at Instituto de Quimica, Universidad Nacional Autonoma de
Mexico (1993-1994), University of Texas at El Paso (1997) and
Universidad de Santiago de Compostela, Spain (1998). He received a
Humboldt Fellowship for a reasearch visit at Universitat Magdeburg,
Germany (1997) and the Gauss Professorship of the Akademie der
Wissenschaften in Gottingen, Germany (1998). He also received visiting
grants from the National Science Foundation (USA, 1992), European
Community (Spain 1993) and British Council (United Kingdom, 1995)
and a NATO Cooperative Research Grant (United Kingdom, 1997). He
authored or co-authored several books (including The Chemistry of
Inorganic Ring Systems, 1970, The Chemistry of Inorganic Homo- and
Heterocycles, 1987; Basic Organometallic Chemistry, 1985,
Organometallics in Cancer Chemotherapy, 1989, 1990 and
Supramolecular Organometallic Chemistry, 1998 in press) and more than
250 research papers and several chapters in some multi-authored books.
His interests cover inorganic ring systems, Main Group Organometallic
and coordination chemistry, organophosphorus and organoarsenic ligands
and Supramolecular Organometallic chemistry. He participated in an

extensive international collaboration with colleagues from United
Kingdom, Germany, Spain, Mexico, Belgium, United States of America,
Brazil, Canada, France, which resulted in numerous joint publications.
After the anti-communist revolution in Roumania (December 1989) he
was elected and served as Rector (President) of “Babes-Bolyai”
University (1990-1993), and in 1998 was elected Vicepresident of the
Roumanian Academy.
Robert Stepto obtained his BSc degree in Chemistry (with Special
Honours in Physical Chemistry) and his PhD degree studying the
Diffusion of Polymers in Solution from the University of Bristol. He
moved to UMIST in 1961 as a Research Fellow in Polymer Crosslinking
in the Department of Polymer and Fibre Science. He was subsequently
appointed to the teaching staff and eventually to Professor of Polymer
Science in the Materials Science Centre, UMIST. He was awarded a DSc


xix
by the University of Manchester in 1987 for his work on Statistical
Studies in Polymer Science. Robert Stepto’s research activities are in the
area of the physical chemistry of polymers including polymerisation
statistics, intramolecular reaction and gelation; the formation, structure
and properties of polymer networks; polymer solutions and mixtures,
covering diffusion, scattering, phase behaviour and intrinsic viscosity;
computational studies of polymer chain behaviour; and the thermoplastic
processing of starch and starch materials. He has well over 200 research
publications to his name and has recently edited a book on Polymer

Networks. He received an Interphex Award for Innovation in production
in the Pharmaceutical Industry for his work on starch processing. He is
currently the European Editor of Computational and Theoretical Polymer

Science, Secretary of the Polymer Networks Group, Chairman of the
IUPAC Commission on Macromolecular Nomenclature and VicePresident of the Macromolecular Division of IUPAC.

David Taylor earned a BSc(Hons) in Polymer Science and Technology
(Chemistry) at the University of Manchester Institute of Science and
Technology (UMIST). During a subsequent period of employment in the
plastics processing industry, David also continued his theoretical research
into the molecular origins of elastomeric behaviour, eventually leading to
the award of an MSc degree in 1995. He then returned to UMIST as a
Research Associate, and has since been engaged in theoretical studies of
polymer network formation, structure and properties, under the guidance
of Professor Bob Stepto. In 1996 David was a visiting scientist in the
Polymer Group at Biosym/MSI (now Molecular Simulations Inc) in San
Diego.

Ulrich Maschke studied Chemistry at the University of Mainz
(Germany) where he received his Diploma in 1989 working on

miscibilities of polymer mixtures. In 1992 he finished his PhD thesis
(Static and dynamic properties of polymer melts studied by neutron
scattering) at the Max-Planck-Institut für Polymerforschung in Mainz
with Professor B Ewen and Professor E W Fischer. In the fell of 1992 he
joined the French National Center of Scientific Research (CNRS) as a
Research Associate (Chargé de Recherche) at the laboratory of
macromolecular chemistry at the University of Lille, France. His current
research interests include the synthesis and analysis of materials
composed of liquid crystals and polymers (polymer dispersed liquid
crystals). He is working together with Professor Mustapha Benmouna
and his group of the University of Tlemcen (Algeria).
Mustapha Benmouna earned a BS degree in Physics at the University of

Algiers in 1969 and in Electrical Engineering in 1971 in Paris. He

obtained a Master’s degree in 1977 and a PhD in 1979 at the University
of Michigan (Ann Arbor, USA) in 1979 with Professor Ziya A Akcasu. In
1984, he earned a PhD in Physics at the University of Strasbourg (France)
with Professor Henri Benoit working on the static and dynamic scattering
properties of polymer mixtures and copolymers. He joined the University
of Tlemcen in Algeria in 1981 as an associate professor and was
appointed full professor in 1986. He was visiting professor of several
universities in Europe (University of East Anglia, England, 1986;


xx
University of Konstanz, Germany, 1987; University of Strasbourg,
France, regularly from 1984 – to date, University of Lille, France, 1996
and 1998) and United States (University of Michigan, 1986; National
Institut of Standards and Technology, Gaithersburg, Maryland and the
University of Maryland, 1995, Tulane University, New Orleans, 1995).
Since 1990, he became a regular visiting professor of the Max-PlanckInstitut für Polymerforschung (Mainz, Germany) collaborating with
Professor E W Fischer, Professor Thomas A Vilgis, Professor Bernd
Ewen and Professor Adam Patkowski. Recently, he joined the group of
Professor Kurt Kremer as a visiting professor. Since 1995, he became
interested in the properties of polymer dispersed liquid crystals and
started a programme of collaboration between the University of Tlemcen
and the University of Lille collaborating with Dr Ulrich Maschke and
Professor Xavier Coqueret. This collaboration is supported by both the
CNRS in France and the Ministry of Education in Algeria.


CHAPTER 1

INTRODUCTION : CYCLIC POLYMERS - THE FIRST 40 YEARS
J. Anthony Semlyen,
University of York, UK
1.1

Preparation and characterisation of cyclic oligomers
and polymers

1.1.1

Early investigations of large cyclics

Some 40 years ago in November 1959, the author was given a tutorial
assignment on synthetic polymers. His tutor at Merton College, Oxford, Dr.
Courtenay Phillips recommended Paul Flory’s book“The Principles of Polymer
Chemistry”[1]. The book describes how polymeric materials such as plastics,
rubbers and fibres are constructed from long chains of covalently bound atoms.
The resultant long chain molecules may consist of tens of thousands or even
hundreds of thousands of atoms. This was established by Hermann Staudinger
in his macromolecular hypothesis, despite the opposing views that polymeric
materials were either ring molecules or were colloidal aggregates of smaller
molecules held together by secondary forces in micellar structures (see, for
example, Ref [1] [2]). While reading “The Principles of Polymer Chemistry”,
the author noticed that the largest well characterised ring molecules described in
the book had only 24 skeletal bonds. Further reading showed that there was a
gap in chemistry waiting to be developed, namely the preparation,
characterisation, investigation and possible application of large ring molecules
with more than 30 skeletal bonds as well as synthetic cyclic polymers with more
than 100 skeletal bonds. The author’s main aim in chemistry since that time was
to try and establish this new subject area both in collaboration with and

alongside other research chemists in this general area. The first edition of
“Cyclic Polymers ” was published some 27 years later in 1986 [3]. In the book,
14 authors described the advances that had been made in the chemistry of both
synthetic and biological cyclic polymers.
The subject of cyclic polymers effectively began with a paper by Jacob
and Wollman [4] about 40 years ago in 1958, who concluded that the genetic
map of bacterial chromosomes of Escherichia coli showed circularity. Further
evidence for the existence of circular DNA was soon established [5] [6] and final
confirmation came from electron microscopy of øX174 DNA [7] (see chapter 7
in Ref. [3]). The discovery of large cyclic molecules in natural biological
systems is described in Ref. [3] as well as in a more recent book [8] in chapters
by Andrzej Stasiak, Harold Scheraga and David Brant and also in this book.
1
J. A. Semlyen (ed.), Cyclic Polymers, Second Edition, 1–46.
© 2000 Kluwer Academic Publishers. Printed in the Netherlands.


2

At the time when the first papers on circular DNA molecules were being
published, there was an upper limit of about 30 skeletal bonds for well
characterised large synthetic ring molecules. The pioneering researches of
Wallace Carothers on high polymeric substances is described in his collected
papers [9]. They show how important new polymers including linear polyamides
and linear polyesters were prepared and characterised. In addition, a number of
large ring molecules were prepared for the first time such as many-membered
cyclic esters and anhydrides. An example of the largest is the macrocyclic ester,
decamethylene octadecanedioate (Figure 1), which has 30 skeletal bonds.

Figure 1 - The chemical structure and model of decamethylene octadecanedioate.

In 1962, a review of the stereochemistry of many-membered rings was
published [10] describing a wide range of large ring molecules including a 30membered macrocyclic polyene [11] (Figure 2) and the first catenane with its
interlocked ring system [12] (Figure 3).
Despite the important advances that had been made in the chemistry of
large organic ring molecules following the characterisation of benzene as the first
ring compound in 1865 (Figure 4), it was developments in siloxane and
polysiloxane chemistry and in chromatographic techniques that resulted in the
preparation of narrow molar mass fractions of the first cyclic polymer, allowing
for detailed investigations of its properties.


3

Figure 2 - The chemical structure and molecular model of a 30 membered macrocyclic
polyene


4

Figure 3 - The chemical structure and molecular model of the first catenane.

Figure 4 - The chemical structure and molecular model of the benzene ring.


5

1.1.2 Large rings in polysiloxane systems

The first report on the production of ring and chain species in

poly(dimethylsiloxane) (PDMS) ring-chain equilibrates was made by Scott [13]
in 1946 and in 1962 Hartung and Camiolo [14] published measured values for
the concentrations of the cyclics
(with
) in PDMS
equilibration reactions in solution in xylene. Carmichael and his coworkers
[15][16] extended these studies and were able to analyse cyclic
dimethylsiloxanes with values of
using gas-liquid chromatography. All
these investigations culminated in the work of Brown and Slusarczuk [17] who
carried out PDMS ring-chain equilibration reactions in the bulk and in solution
in toluene. In their base catalysed solution reaction, the siloxane concentration
was
and the temperature was 383 K.
Under the conditions used by Brown and Slusarczuk nearly all the
material obtained is cyclic, with only small amounts of high molar mass chains
and the latter are well separated from the cyclic species. Furthermore, for this
reaction, in principle the individual cyclic concentrations produced should be
calculable by application of the Jacobson-Stockmayer theory [18] and the
distribution of linear species by the Flory relationships for linear condensation
polymers (see Ref. 1). Thus, the Brown and Slusarczuk reaction in toluene gave
an opportunity for the preparation of narrow molar mass fractions of cyclic
polymers with an average up to 1000 skeletal bonds, provided that suitable
analytical and preparative techniques were available. From the point of view of

characterisation, it would also be an advantage to calculate the individual
concentrations of cyclic and linear species in such equilibrates and this was also
undertaken [19].
Early experiments on gas-liquid chromatography (GLC) were carried out
by James and Martin [20] and the first book on the subject of gas

chromatography was written by Courtenay Phillips [21]. The technique became
so well developed that it could be used to analyse cyclics
with up
to 100 skeletal bonds, when OV17 from the Field Instrument Company is used
as the stationary liquid phase and Embacel is used as the solid support [22]. An
example of the GLC analysis of a cyclic fraction is shown in Figure 5.


6

Figure 5 - Gas-liquid chromatogram of a dimethyl siloxane fraction consisting of cyclics
(with x=7-20).

For dimethylsiloxane rings with numbers of skeletal bonds in the range
100-1000, the resolution of individual cyclics by GLC is not possible and so
cyclic fractions were analysed in the author’s laboratory using the technique of
analytical gel permeation chromatography (GPC) (otherwise known as size
exclusion chromatography). This technique was first described by Moore [23]
and preparative GPC was developed shortly afterwards (see, for example, Ref.
[24]). The preparative GPC instrument used to obtain cyclic fractions of PDMS
at York was designed and constructed by David Sympson [25]. The results of a
typical fractionation are shown in Figure 6 and the dispersities of the individual
fractions were all in the range
In the higher molar mass
fractions obtained by preparative GPC, appreciable amounts of linear species are
present but the rings can be separated from the chains very effectively, as
described in Ref. [25], Once a whole range of narrow fractions of PDMS cyclics
had been obtained, these first cyclic polymers could be characterised and their
properties investigated. This was done in collaboration with 20 other University
research groups and with Dow Corning Ltd., resulting in a range of publications

(see, for example, Ref. [26] [27]). Some of these properties will be described
later in the chapter.