氰乙基羟丙基壳聚糖的溶致和热致液晶性研究

从壳聚糖出发先羟丙基化再氰乙基化,合成了氰乙基羟丙基壳聚糖(羟丙基的摩尔取代度为3.2,氰乙基的取代度为1.0).氰乙基羟丙基壳聚糖(CNHPCS)和羟丙基壳聚糖(HPCS)两者都有胆甾型溶致液晶性,浓溶液呈现指纹状织构.在二氯乙酸中,前者的临界浓度(29%,质量分数,下同)高于后者(17%).这一结果可以用引入氰乙基增加了分子间作用力从而使得链刚性增加来解释.CNHPCS在熔点193℃和分解温度220℃之间很窄的温区内观察到有热致液晶胆甾相.CNHPCS固体膜的胆甾相螺距采用激光小角光散射法测定,结果与偏光显微镜测得的数值一致.

Studies on Lyotropic and Thermotropic Liquid Crystalline Behavior of Cyanoethylhydroxypropyl Chitosan

Cyanoet hylhydroxypropyl chitosan was synthesized by hydroxypropylation of chitosan followed by cyanoet hylation.The degree of hydroxypropylation and cyanoet hylation was 3.2 and 1.0 respectively.Both cyanoet hylhydroxypropyl chitosan(CNHPC'S)and hydroxypropyl chitosan (HPCS)demonst rated lyot ropic liquid crystalline behaviors, and fingerprint texture was observed in Their concent rated solutions implying The presence of cholesteric phase.The critical concent ra-tion of HPCS in DCA(29%)is higher than CNHPCS's(17%), owing to The enhanced chain rigidity cont ributed by The int roduction of cyanoet hylgroup.In The case of CNHPC'S, cholesteric Thermot ropic mesopHase could be observed between its melting point 193℃ and decomposition temperat ure 220℃ measured by Both DSC and polarized light microscope.SALS was employed to determine The pitch of cholesteric phase in CNHPC'S as received film.The results were consis-tent with those of PLM.