Helical Structure and Supramolecular Structure of Cellulose Derivatives in Solution

在这个研究项目中，我们研究了纤维素衍生物三苯基氨基甲酸酯纤维素（CTC）在溶液中的局部构象、液态结晶度和浓缩溶液的动力学性质（粘度和扩散）。研究结果如下：(1)从之前的构象能计算可知，纤维素链上的每个葡萄糖残基都具有两个能量稳定的构象（左旋3/1螺旋和扩展2/1螺旋）。从特性粘度对温度和分子量的依赖关系出发，研究了纤维素链在溶液中的局部构象。(2)确定了CTC浓溶液胆甾相形成的临界浓度与分子量的函数关系。结果与硬链聚合物溶液的统计力学理论进行了比较。(3)测定了CTC溶液从稀到浓的零剪切粘度随CTC分子量和浓度的函数关系。结果与硬链聚合物溶液的聚合物动力学理论（模糊圆柱体理论）进行了比较。(4)采用动态光散射和脉冲场梯度核磁共振分别测量了CTC四氢呋喃溶液的相互扩散系数和自扩散系数。与模糊圆柱理论相比，后一种系数较好，而前一种系数较差。(5) CTC的胆甾THF溶液转化成胆甾凝胶，然后随着聚合物浓度的增加胆甾颜色消失。对这种凝胶行为进行了初步实验。

In this research project, we have investigated the local conformation in solution, liquid crystallinity and dynamic properties (viscosity and diffusion) of concentrated solutions for a cellulose derivative, cellulose tris(phenyl carbamate) (CTC). The research results are as follows.(1) It is know that each glucose residue in the cellulosic chain takes two energetically stable conformations (a left-handed 3/1 helix and extended 2/1 helix) from previous conformation energy calculations. The local conformation of the cellulosic chain in solution was investigated from the temperature and molecular weight dependencies of the intrinsic viscosity.(2) The critical concentration for the cholesteric phase formation for concentrated THE solutions of CTC was determined as a function of the molecular weight. The results were favorably compared with a statistical mechanical theory for stiff-chain polymer solutions.(3) Zero-shear viscosities of THE solutions of CTC from dilute through concentrated regime were measured as functions of the molecular weight and concentration of CTC. The results were favorably compared with a theory for polymer dynamics (the fuzzy cylinder theory) for stiff-chain polymer solutions(4) The mutual-and self-diffusion coefficients for THF solutions of CTC was measured up to a concentrated regime by dynamic light scattering and pulse-field gradient NMR, respectively. While the latter coefficient was favorably compared with the fuzzy cylinder theory, the former coefficient was not.(5) Cholesteric THF solutions of CTC were trartsformed into cholesteric gels and then the cholesteric color was disappeared with increasing the polymer concentration. A preliminary experiment for this gelation behavior was started.