Pergamon Prog. Polym. Sci., Vol. 19, 843 945, 1994 © 1994 Elsevier Science Lid Printed in Great Britain. All rights reserved 0079 6700/94 $26.00 0079-6700(94)00023-9 ROTAXANES, CATENANES, POLYROTAXANES, POLYCATENANES AND RELATED MATERIALS HARRY W. GIBSON, MUKESHC. BHEDA and PAUL T. ENGEN Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg. VA 24061, U.S.A. CONTENTS I. Introduction 843 1.1. Polymer topology 844 1.2. Polymer blends 847 1.3. Future needs 848 2. Low molecular weight catenanes and rotaxanes 848 2.1. Definitions 848 2.2. Synthetic approaches and properties 850 2.2.1. The statistical approach 850 2.2.2. Synthesis about a central core: the directed or chemical conversion approach :359 2.2.3. The template approach ',363 3. Oligomeric rotaxanes and catenanes :~86 3.1. Statistical threadings ,~86 3.2. Template threadings 896 4. Polymeric rotaxanes 899 4.1. Classes of polyrotaxanes 899 4,2. Approaches to main chain systems 166 901 4.3. Approaches to main chain systems 167 919 4.4. Approaches to side chain systems 168 924 4.5. Approaches to side chain systems 169 926 5. Polymeric catenanes 929 5.1. Classes of polycatenanes 929 5.2. Approaches to polycatenanes of type 3 930 5.3. Approach to polycatenanes of type 246 933 5.4. Approaches to polycatenanes of type 247 934 5.5. Approaches to polycatenane systems of type 248 934 5.6. Approaches to polycatenanes of types 249 and 250 938 6. Summary, conclusions, prospectus 938 Acknowledgements 940 References 940 1. INTRODUCTION The increasing use of synthetic polymers to replace or supplement more traditional materials has stimulated research to produce more versatile polymeric structures covering a wider range of properties. To exploit the existing technologies and make logical extensions, fundamental structure-property relationships are being studied extensively. The structure-property relationships can be dealt with under two broad areas: (i) chemical aspects; and (ii) architectural aspects, l(a) (i) Chemical aspects deal with information on the molecular structure of the macromolecules, including the type 843