Interfacial Properties for liquid-crystalline Polymer solutions

本研究主要探讨溶致液晶高分子溶液中各向同性相与液晶相共存时的界面性质，主要研究（1）各向同性-各向异性界面附近各向异性相中的分子排列，（2）界面张力与链长的关系，（3）界面张力对链刚度的依赖性。我们选择了刚性和半柔性的聚合物，（一种三螺旋多糖）、聚（异氰酸正己酯）（PHIC）和聚（异氰酸正丁酯）（PBIC）的本体溶液性质进行了详细的研究。(1)通过偏振显微镜观察各向同性液晶界面，该偏振显微镜具有与正交偏振器的方向成45 °取向的补偿器，并且观察结果显示刚性聚合物分子平行于界面排列。(2)用悬滴法和静滴法测定了叶绿素多糖、PHIC和PHIC/PBIC混合物溶液中共存的各向同性相和液晶相之间的界面张力。对于叶绿素多糖溶液，界面张力几乎与聚合物分子量成反比。另一方面，PHIC溶液的界面张力几乎与聚合物分子量无关，前者的分子量依赖性与理论的棒状聚合物溶液，后者分子量的独立性是一致的预测蠕虫状链解决方案的理论在coil limit.It是已知的PHIC是更灵活的比dichrophyllan。我们还发现，界面张力强烈地依赖于分子量分布和化学不同的聚合物物种的添加。

In this research project, we have dealt with properties of interface between coexisting isotropic and liquid-crystal phases of lyotropic liquid-crystalline polymer solutions.Our utmost concern was to examine (1) the molecular alignment in the anisotropic phase near the isotropic-anisotropic interface, (2) the dependence of the interfacial tension on chain length, and (3) the dependence of the interfacial tension on chain stiffness.We have chosen well characterized rigid and semiflexible polymers, schizophyllan (a triple-helical polysaccharide), poly(n-hexyl isocyanate) (PHIC), and poly(n-butyl isocyanate) (PBIC), whose bulk solution properties have been studied in detail.(1) The isotropic-liquid-crystal interface was observed by a polarizing microscope with a compensator oriented at 45ﾟ to the directions of the crossed polarizers, and the observations revealed that rigid polymer molecules align themselves parallel to the interface.(2) The interfacial tension between coexisting isotropic and liquid-crystal phases of solutions of schizophyllan, PHIC, and PHIC/PBIC mixtures was measured by the sessile or pendant drop method.For schizophyllan solutions, the interfacial tension is almost inversely proportional to the polymer molecular weight.On the other hand, the interfacial tension for PHIC solutions is almost independent of the polymer molecular weight The former molecular weight dependence agrees with the prediction of theories for rodlike polymer solutions, and the latter molecular weight independence is consistent with the prediction of a theory for wormlike-chain solutions in the coil limit.It is known that PHIC is more flexible than schizophyllan.We also found that the interfacial tension strongly depends on the molecular weight distribution and addition of chemically different polymer species.