Novel High-Performance Materials from Starch. 1. Factors Influencing the Lyotropic Liquid Crystallinity of Some Starch Ethers Wenyan Zhao, † Andrzej Kloczkowski, and James E. Mark* Department of Chemistry and the Polymer Research Center, University of Cincinnati, Cincinnati, Ohio 45221-0172 Burak Erman School of Engineering and the Polymer Research Center, Bogazici University and the TUBITAK Advanced Polymeric Materials Research Center, Bebek 80815, Istanbul, Turkey Received August 11, 1997 Starch ethers having side chains of various lengths, controlled and uniform degrees of substitution, and various amylose/amylopectin ratios were obtained by a one-step chemical modification of starch. Factors influencing the phase behavior of these starch ethers were carefully examined, and the ones having short side chains were found to exhibit lyotropic liquid crystallinity over wide ranges in degree of substitution and amylose/amylopectin ratio. The starch ethers having longer side chains failed to exhibit phase separation due to insufficient degrees of substitution. They generally possessed enhanced hydrophobicity relative to starch yet still had controllable numbers of free hydroxyl groups. The liquid crystallinity thus produced makes them ideal candidates for a novel processing technique designed specifically for permanently orienting main-chain, lyotropic, liquid-crystalline polymers. Introduction Biodegradable polymers have become of great inter- est, particularly over the past few years, owing to environmental concerns over the disposal of synthetic polymers. 1-11 The challenge in replacing conventional synthetic polymers is to design materials that exhibit structural and functional stability during processing, storage, and use, yet are susceptible to microbial and environmental degradation upon disposal, without any adverse environmental impacts. 3 There are several ways of designing such biodegrad- able materials. 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