一种手性甲壳型液晶高分子的稀溶液行为及链刚性

用激光光散射和粘度法研究了一系列窄分子量分布的新的手性甲壳型液晶聚合物P1～P6的溶液行为及其链刚性.研究发现四氢呋喃是聚合物P1～P6的良溶剂.在四氢呋喃溶液中,聚合物P1～P6的特性粘数[η]和均方根旋转半径z12对重均分子量Mw的依赖关系分别是[η]=(2.75±0.05)×10-3Mw0.78±0.02和z12=(1.53±0.04)×10-2Mw0.60±0.01.按照YamakawaFujiiYoshizaki蠕虫状圆筒模型的粘度理论和BohdaneckyBushin表达式,求得聚合物的单位围长摩尔质量ML=(29.8±1.0)×102nm,构象保持长度q=(15.4±3.0)nm.q和MHS方程指数α的值说明这类在结构上属于侧链型液晶高分子的聚合物在良溶剂四氢呋喃中呈现比较伸展的刚性链构象,其链刚性与半刚性主链液晶高分子的相似.

DILUTE SOLUTION BEHAVIOR AND CHAIN-STIFFNESS OF A CHIRAL MESOGEN-JACKTED LIQUID CRYSTAL POLYMER

A series of optically active mesogen-jacketed liquid crystal polymers with narrow polydispersities (P-1～P-6) were studied by a combination of static and dynamic laser light scattering techniques and viscosity measurements in THF at 25℃.It is found that THF is a good solvent for the polymers studied.The dependences of the intrinsic viscosity [η] and root mean-square radius of gyration _z 1/2 of the polymers on weight-average molecular weight M_w are [η]=(2.75±0.05)×10 -3 M_w 0.78±0.02 and _z 1/2=(1.53±0.04)×10 -2 M_w 0.60±0.01,respectively,in THF at 25℃.According to Bohdanecky-Bushin's method based on Yamakawa-Fujii-Yoshizaki's theory for worm-like chain cylinders,the molar mass per unit contour length M_L and the persistence length q were estimated to be (29.8±1.0)×102?nm and (15.4±3.0)?nm,respectively.The values of the exponent α of Mark-Houwink-Sakurada equation and q indicate that these liquid crystal polymers of the side-chain type have an extended conformation in dilute solutions as most main-chain liquid crystal polymers.