The papersin this volume are as a resultofcontributions given at the NATO Advanced Study Institute heldat L1andinam Building, University CollegeofWales, Aberystwyth, 10 - 23 September 1989. The Institute considered the physical and chemical propertiesof a variety ofcolloidal systems ranging from simple micellar solutions to concentrated colloidal dispersions. The purpose ofthe NATO Advanced Study Institute was to create a forum so that research scientists working in different areas concerned with colloid science could interact. The emphasL oft1"l.;: contributions were on the interpretation ofthe different experimental and theoretical approach to give information on the structure, dynamics and equilibrium propertiesofthese systems. The application ofseveral different techniques in colloid science have been described; new developments and perspectives have been covered by several authors. The present volume reviews the current stale ofthe art in this area and it is hoped that it will be used as an incentive for further studies particularlywith reference to new areas ofresearch. In the organisation ofthe scientific programme for the NATO meeting we would like to acknowledge the assistance ofProfessors J. Lyklema, D. G. Hall and J. Holzwarth. We wish to thank Miss Mandy Rudd for all the secretarial assistance in setting up the meeting and for the invaluable assistance in preparing the manuscripts. In connection with the proceedings we would also like to thank Miss Sandra Fahy for assistance. The help of Paul Jones and Mrs G. Wyn-Jones during the meeting is also gratefully acknowledged.

The polydiacetylenes are a class of polymers that are attrac ting increasing attention worldwide. There are many reasons for this interest one of the most important being the availability of many polydiacetylenes as macroscopic, high quality, single crystals. This fact was first reported in the pioneering work of Prof. G. Hegner on the solid-state polymerization of disub stituted diacetylenes in the late 1960s. Since then studies of the polymerization process and the properties of monomers and polymers have advanced understanding of solid-state reactivity and the physiCS of quasi-one-dimensional materials. More recently work on soluble polydiacetylenes, gels and films has been of interest for both academic and technological reasons. Progress in this area has required a combination of research disciplines ranging from synthetic organic chemistry to solid state physics. The interdisciplinary effort required for success ful research in polydiacetylenes was reflected in the mix of chemists, physicists and materials scientists who attended the Workshop. The emerging potential for commercial applications of polydiacetylenes was also evident in the nearly equal partici pation of academic and industrial/government scientists. The WOrkshop was the first major international meeting to focus solely on polydiacetylenes. It provided a forum in which problems of mutual interest could be discussed by scientists with diverse backgrounds and interests. It also satisfied the need for a review of the science of these materials at a time when this basic understanding is leading to technological applications."