Preface

IMPRESSIVE ADVANCES in the ability to modify, regenerate, and reshape cellulose and polysaccharide derivatives with unique chemical, physical, and physiological properties have raised the interest in this most important biological macromolecule over the past decade. Cel­lulose derivatives have received much attention from authors with diverse research, clinical, and business interests; and this interest has created an opportunity for a broad display of topi­cal discussions with varying degrees of technical depth. The launching of a new, nationwide research program in Germany focusing on the design of molecular and supramolecular struc­tures based on cellulose and cellulose derivatives, by the Deutsche Forschungsgemeinschaft (DFG, the equivalent of the National Science Foundation in the United States), has attracted scientists from a variety of disciplines.

This book was developed from a symposium titled "Recent Advances in Cellulose Modi­fication", held at the 212th National Meeting of the American Chemical Society, in Orlando, Florida, August 25-29, 1996. The symposium provided a forum for organizing an integrated discussion of the current state of the art. It was organized with the intent of bringing together scientists from academia and industry in the expectation that the new insights gained would be useful for the development of novel, value-added materials from this polymer which is basic to all plants.

Impulses for the new focus on cellulose derivatives originated from several sources:

• availability of new cellulose sources, especially bacterial cellulose • new cellulose solvents and their corresponding regenerated fibers • new regioselective modification methods • new insights into the anisotropic solution states of (especially lyotropic liquid-crystalline)

cellulose derivatives • a new understanding of the enzyme systems involved in cellulose degradation • new, chirally active cellulose-based separation materials • new, highly ordered thin film architectures of cellulose derivatives prepared by the Lang-

muir-Blodgett technique

This book highlights advances in (1) both homogeneous and heterogeneous phase modi­fication of cellulose to create unusual derivatives, often with regioselective substitution pat­terns, (2) analysis of selectively and specifically modified derivatives, (3) issues such as the self-assembly of cellulosic macromolecules in dilute and concentrated solutions as well as in solids, and (4) supramolecular architectures potentially useful in novel sensors, immunoas­says, membranes, and biocompatibilized surfaces.

The first section of this book, "Modification Chemistry", shows that recent research on chemical conversion of cellulose is mainly directed toward the synthesis of functionalized de­rivatives with well-defined primary structures, both within the anhydroglucose repeat unit and along the polymer chain. Moreover, nonconventional functional groups with special properties are playing a dominant role in advanced cellulosics. In order to design new polymers based on cellulose, special synthesis concepts are introduced to create reactive microstructures by, for

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example, induced phase separation. Nucleophilic displacement reactions and selective cellu­lose oxidations are discussed as well. Examples are given for the advanced manufacture of conventional esters and ethers.

A fast and reliable supply of comprehensive analytical data is an indispensable prerequi­site for considering and pursuing new routes of synthesis and for controlling chemical proc­esses in cellulose functionalization. In the section "Chemical and Molecular Structure", recent results in adapted instrumental techniques are presented. In particular, NMR, Fourier-transform infrared, and chromatographic techniques are providing new insights into molecular structures and intermolecular interactions. The determination of molecular weights and mo­lecular-weight distributions, and their changes during chemical, physical, and enzymatic modifications, is discussed as well.

Based on the synthesis and structure characterization of fiinctionalized cellulose deriva­tives, the processing of materials with defined supramolecular architectures is one of the most important areas of cellulose research. The present state of the art in the design of supra­molecular structures in the liquid and solid state, and the search for promising applications of these structures, is summarized in the section "Supramolecular Structures". The successful engineering of nanostructures and defined colloids yields insight into self-organization princi­ples. The study of mesophase formation of cellulose derivatives with a defined primary struc­ture provides a better understanding of liquid-crystalline systems. Tailored cellulosic com­pounds are employed to design ordered supramolecular structures that can find application as sensors, light-wave conductors, and selective membranes.

We express our appreciation to the American Chemical Society's Cellulose, Paper, and Textile Division for sponsoring the symposium. The editors are indebted to their respec­tive institutions, the Friedrich Schiller University of Jena, Germany and the Virginia Poly­technic Institute and State University, Blacksburg, VA, for financial and logistic support of this endeavor. We also thank Mark Fitzgerald and David Orloff of the American Chemical Society Books Department, and Mary Holliman of Pocahontas Press, Blacksburg, VA for their conscientious efforts to ensure timely review and completion of the book.

THOMAS HEINZE Institut für Organische Chemie und

Makromolekulare Chemie der Friedrich Schiller-Universität Humboldtstrasse 10 D-07743 Jena, Germany

WOLFGANG G. GLASSER Department of Wood Science and Forest Products Virginia Polytechnic Institute and State University Blacksburg, V A 24061-0324

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In Cellulose Derivatives; Heinze, T., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1998.