热塑性甲壳素衍生物N,O-苄基壳聚糖的合成及表征

Chitin derivatives are difficult to be melten because of their very strong inter-molecular and intra-molecular hydrogen bonds. In this paper, N,O-benzyl chitosan was synthesized by means of phase-transfer method. The total degree of substitution for this derivative was 0 8 as determined with 1H NMR and the degree of substitution on nitrogen was 0 3 as determined with elemental analysis. This is a thermoplastic chitin derivative. Its melting point was 470 K as measured with DSC. A viscous isotropic melt occurred at the temperatures between the melting point and the decomposition temperature(513 K) while N,O-benzyl chitosan was heated on a hot stage. DSC results agreed with the results of microscopy observation. The benzyl group can not form hydrogen bonds. It is also non-polar and has larger volume. These factors weaken the interactions between chitosan chains, and therefore decrease the melting point, which was lower than the decomposition temperature. As a result, N,O-benzyl chitosan was able to melt

甲壳素类液晶高分子的研究Ⅶ.N,O-苄基壳聚糖的胆甾螺旋行为

N ,O-苄基壳聚糖在浓溶液中形成胆甾液晶相 .用圆偏光二向色性谱 (CD)研究了这一聚合物的螺旋行为 ,主要包括螺距和螺旋方向 .浓度越高 ,螺距P越大 ,意味着胆甾相的扭转力随浓度增加而减弱 .CD谱图上观测到两类吸收 ,即在 5 70nm附近较宽但较强的吸收和 330nm附近较尖但较弱的吸收 .前者归属于胆甾相层片的超分子螺旋构象 ,而后者可以归属于分子链的螺旋构象 .改变浓度或溶剂性质时这两个层次的构象都会发生符号的变化 .提高浓度 (固定二氧六环为溶剂 )时两种螺旋结构先后发生反转 .以氯仿为溶剂 (固定浓度为 6 5 % )时两种螺旋结构均为左旋 (正Cotton效应 ) ,但二氧六环和四氢呋喃为溶剂时均变为右旋 (负Cotton效应 ) .溶剂的影响可能与溶剂和高分子间形成氢键的能力有

Synthesis and characterization of thermoplastic chitin derivative N,O-benzyl chitosan

Chitin derivatives are difficult to be melten because of their very strong inter-molecular and intra-molecular hydrogen bonds. In this paper, N, O-benzyl chitosan was synthesized by means of phase-transfer method. The total degree of substitution for this derivative was 0.8 as determined with H-1 NMR and the degree of substitution on nitrogen was 0.3 as determined with elemental analysis. This is a thermoplastic chitin derivative. It's melting point was 470 K as measured with DSC. A viscous isotropic melt occurred at the temperatures between the melting point and the decomposition temperature(513 K) while N,O-benzyl chitosan was heated on a hot stage. DSC results agreed with the results of microscopy observation. The benzyl group can not form hydrogen bonds. It is also non-polar and has larger volume. These factors weaken the interactions between chitosan chains, and therefore decrease the melting point, which was lower than the decomposition temperature. As a result, N,O-benzyl chitosan was able to melt