SIZE EXCLUSION CHROMATOGRAPHY

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1 SIZE EXCLUSION CHROMATOGRAPHY Edited by B.J. HUNT Polymer Research Group Department of Chemistry University of Lancaster and S.R. HOLDING RAPRA Technology Ltd Shrewsbury Springer-Science+Business Media, B.V.

2 1989 Springer Science+Business Media Dordrecht Originally published by Chapman and Hall in 1989 Softcover reprint of the hardcover 1 st edition 1989 All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, recording or otherwise,, without prior permission of the Publishers. British Library Cataloguing in Publication Data Size exclusion chromatography. 1. Chromatography I. Hunt, B.J. II. Holding, S.R. 543'.089 ISBN ISBN (ebook) DOI / For the USA, International Standard Book Number is {) Phototypesetting by Thomson Press (India) Limited, New Delhi.

3 Preface There is a large and increasing variety of polymers currently in use both for domestic and industrial applications. The properties of polymers are determined not only by their chemical type, but also by their molecular mass and molecular mass distributions. However, while the chemical type of polymers can be determined relatively easily, the average molecular masses and molecular mass distributions are more difficult to measure. The molecular mass averages of a polymer are measured by specialized and complex techniques such as light scattering (for weight average) and osmometry (for number average). Thus, complete characterization of the molecular mass distribution of a polymer by such means requires separating the sample into many fractions which can then be examined individually. Since size exclusion chromatography was introduced as a rapid and straightforward technique for the characterization of polymer molecular mass distributions, there have been tremendous increases in development and applications, and it was felt appropriate to bring together into a single volume the information required by scientists from many disciplines who wish to use the technique. This book should be useful to existing users, those who are new to the technique, and those who may be familiar with the basic technique and now wish to extend their capabilities to more complex applications (or to consider the potential of a number of related techniques). The book will also be of general interest to the experienced liquid chromatographer. In Part 1 the basic principles of the technique are discussed, including the theoretical aspects, a description of the hardware requirements necessary for carrying out SEC, and a chapter on data analysis. Part 2 deals with the more complex applications of SEC and has been written by specialists familiar with carrying out SEC at elevated temperatures, characterizing copolymers (including the technique of 'orthogonal chromatography'), and analysing small molecules and water-soluble polymers. In Part 3, a number of related techniques are covered which may prove to be more suitable than SEC for certain applications. These included 'field-flow fractionation', 'supercritical fluid chromatography' and 'hydrodynamic chromatography'. Finally, in the appendices, comprehensive tables of data are provided which will be of use to all practitioners of SEC. iii

4 iv PREFACE Finally, a note on terminology and notation. Originally, the technique of SEC was known as gel permeation chromatography (GPC), and this term is still used today. While some writers draw distinctions between size exclusion chromatography (SEC) and gel permeation chromatography (GPC), for convenience and clarity we treat these terms as equivalent and use only the single term 'size exclusion chromatography' (SEC). Also, although molecular mass is still referred to as molecular weight by some workers, it is quite clear that molecular mass has now taken over as the most widely accepted term, and hence has been used throughout this book. We thank all the authors for the contributions to the book, and our colleagues for their advice, comments and helpful discussions. BJH SRH

5 Contents Part 1: Fundamentals of SEC 1 Theoretical background 3 B.l. HUNT 1.1 Introduction to SEC Basic chromatographic parameters Column efficiency and plate number Resolution Pore size, pore volume and porosity Mechanisms of size exclusion chromatography Theories of retention in SEC II References 12 2 Instrumentation and practice 14 B.l. HUNT 2.1 Introduction and background Hardware Solvent reservoir Solvent pump Injectors Columns Detectors Data systems Special equipment Practical aspects Equipment Sample preparation Operation 40 References 40 3 Calibration and data analysis 42 S.R. HOLDING 3.1 Introduction Conventional calibration procedures The use of narrow-mmd calibrants The use of broad-mmd calibrants Universal calibration Polystyrene equivalent molecular masses Defining an SEC calibration Internal marker Band-broadening correction 48 V

6 vi CONTENTS Detector response corrections Reproducibility of results Alternative calibration procedures Low-angie laser light-scattering detector Viscosity detector 3.5 Conclusions References Part 2: Applications 4 High-temperature size exclusion chromatography M.R. HADDON and J.N. HAY 4.1 Introduction 4.2 Current instrumentation Self-contained SEC instruments Modular systems 4.3 The choice of solvent 4.4 Experimental procedures 4.5 Polymer systems Polyethylene and copolymers Polypropylene and copolymers Polystyrene Poly(ethylene terephthalate) Nylon Poly(ether ether ketone) Poly(phenylene sulphide) 4.6 Conclusions References 5 Copolymer analysis S. MORI 5.1 Introduction 5.2 Molecular mass averages Construction of a calibration curve Determination of absolute molecular mass Correction of detector response 5.3 Composition and chemical heterogeneity UV-RI dual detector system An infrared detector Other techniques 5.4 Combination with other chromatographic methods Orthogonal chromatography Adsorbtion chromatography-sec SEC-precipitation liquid chromatography SEC-thin layer chromatography References 6 SEC of small molecules D.E. HILLMAN and C. HEATHCOTE 6.1 Introduction 6.2 Selection of experimental conditions Column systems Choice of solvent Choice of flow rate Detector system

7 CONTENTS vii Multidetector SEC Molecular size-elution volume relationships Applications Waxes Hydrocarbon oils Asphalts and pitches Coal liquids Oligomers Additives in plastics Total polymer content Fatty acids, glycerides and polymeric acids Rosin and derivatives Explosives and propellants Organometallic compounds Miscellaneous applications Aqueous SEC 167 References Aqueous size exclusion chromatography 170 Y. KATO 7.1 Introduction 7.2 Supports for high-performance aqueous SEC Hydrophilic-polymer-based support Silica-based support Interactions between samples and supports Selection of chromatographic conditions and applications Non-ionic polymers Anionic polymers Cationic polymers Amphoteric polymers Suitable eluents for various types of water-soluble polymers Conclusions 187 References 187 Part 3: Special techniques Field-flow fractionation: an alternative to size exclusion 191 chromatography J. CALVIN GIDDINGS 8.1 Introduction Thermal FFF: characteristics and advantages Essential background theory Applications of thermal FFF Applications of other FFF methods 212 References Supercritical fluid chromatography 217 K.D. BARTLE, I.L. DAVIES and M.W. RAYNOR 9.1 Introduction SFC in comparison with'other chromatographic methods Apparatus for SFC Operating parameters in SFC mobile phases 223 9,5 Applications of SFC to polymers and polymer-related materials Oligo- and polystyrenes 229

8 viii CONTENTS Other vinyl polymers Silicones (polysiloxanes) Polysaccharides Polyethers and polyglycols Polyesters Polyolefins and waxes Other polymer systems 243 References Hydrodynamic chromatography AJ. McHUGH 10.1 Introduction 10.2 Comments on mechanisms 10.3 Hardware and performance characteristics Apparatus, materials and operating conditions Size calibration Factors affecting resolution Applications 10.4 Particle size distribution analysis 10.5 Comments on modelling and operational characteristics 10.6 Concluding comments References Appendix 1 Appendix 2 Appendix 3 Appendix 4 Appendix 5 Index Suppliers of equipment for SEC Polymers standards and suppliers Recommended solvents and operating temperatures Mark-Houwink parameters for a range of polymers and solvents Solvent properties

9 Contri butors Dr K.D. Bartle Dr I.L. Davies Professor J. Calvin Giddings Dr M.R. Haddon Dr J.N. Hay Mrs C. Heathcote Dr D.E. Hillman Dr S.R. Holding Department of Physical Chemistry University of Leeds Leeds LS2 9JT, UK Department of Physical Chemistry University of Leeds Leeds LS2 9JT, UK Department of Chemistry University of Utah Salt Lake City Utah 84112, USA Department of Chemistry University of Birmingham Birmingham B15 2TT, UK Department of Chemistry University of Birmingham Birmingham B15 2TT, UK DQA/TS Royal Arsenal East Woolwich London SE18 6TD, UK DQA/TS Royal Arsenal East Woolwich London SE18 6TD, UK RAPRA Technology Ltd Shaw bury Shrewsbury SY 4 4NR, UK

10 x Dr B.J. Hunt Dr Y. Kato Professor A.J. McHugh Dr S. Mori Dr M.W. Raynor CONTRIBUTORS Polymer.Research Group Department of Chemistry University of Lancaster Lancaster LA1 4Y A, UK Central Research Laboratory Tosoh Corporation Tonda Shinnanyo Yamaguchi 746, Japan Department of Chemical Engineering University of Illinois Urbana Illinois 61801, USA Chemistry Department of Industry and Resources Mie University Mie 514, Japan Department of Physical Chemistry University of Leeds Leeds LS2 9JT, UK

Size Exclusion Chromatography

Springer Laboratory Size Exclusion Chromatography Bearbeitet von Sadao Mori, Howard G Barth 1. Auflage 1999. Buch. xiv, 234 S. Hardcover ISBN 978 3 540 65635 7 Format (B x L): 15,5 x 23,5 cm Gewicht: 1170