Studies on chitin-based liquid crystalline polymers III. Effect of degree of substitution and molecular weight on the liquid crystalline behavior of cyanoethyl chitosan
- 化学化工－已发表论文 
Alkali-chitosan method was employed to synthesize cyanoethyl chitosan (CNCS) with different degree of substitution (DS) from chitosan by controlling the reaction time. The effect of DS (from 0.36 to 1.21) on he liquid crystalline behaviors of CNCS was investigated. The change of DS showed no obvious influence on the critical concentration (C*) of liquid crystalline-isotropic transition for CNCS/dichloroacetic acid (DCA) solution, because a small substitution degree is large enough to destroy most of the inter-and-intramolecular hydrogen banding. High molecular weight (M-W) chitosan was depolymerized by nitrous acid to get chitosans of different M-W, proceeded by cyanoethylation using alkali chitosan method to synthesize CNCS of different M-W. Investigation was carried to the determine the effect of Mw on the lyotropic liquid crystalline behaviors of CNCS. The C* of CNCS/DCA solution decreased significantly with the increase of M-W. The relatively low C* of CNCS and their obvious dependence on Mw imply that CNCS is a semi-rigid natural polymer with relatively high chain rigidity.