The effects of molecular weight

degree of substitution and side chain length on the liquid crystalline behaviors of chitin derivatives have been studied.It is known that the molecular weight affects the liquid crystalline behaviors evidently.To study the effect of degree of deacetylation (D.D.)

the samples with different D.D. but with same molecular weight must be prepared.These samples were prepared by acetylating chitosan with different amount of acetic anhydride and different reaction time.The method took the advantage of less degradation of molecular chains and no acetylation on —OH of C3 and C6.The chitosans with different D.D.all exhibited typical liquid crystalline texture.The chitosan sample with about 50% D.D. was found to be water soluble and have the maximum critical concentration of lyotropic liquid crystal in both dichloroacetic acid and water.The critical concentration values in water were much lower than those with the same degree of deacetylation in dichloroacetic acid.The poorer liquid crystallinity of chitosan with about 50% D.D.can be explained by the random distribution of acetylamino-D-glucose units and amino-D-glucose units.