Studies on Semi-Rigid Main-Chain Liquid Crystalline Polymers Composed of Symmetric Aromatic Diimides

已知由对称芳二亚胺组成的聚合物在许多情况下不形成液晶相，而含有不对称芳二亚胺的聚合物则倾向于出现液晶熔体。本文制备了由对称的对苯基二亚胺和对苯基二亚胺组成的聚酰亚胺-碳酸亚胺和聚酰亚胺-酯亚胺，并研究了它们的热性能和介形性能，以揭示聚合物结构与LC性能之间的关系。用二酐和氨基醇衍生的联苯二亚胺和对苯二亚胺的二醇与氨基羧酸制备的二亚胺的碳酸二苯酯或二酯熔融缩聚，合成了同聚和共聚（亚胺-碳酸酯）或同聚和共聚（酯-亚胺）。DSC测量、结构的偏光显微镜观察、变温x射线分析和混相测试表明，具有均匀亚甲基链的聚合物在没有联苯单元等传统介源的情况下形成了对映相。富对三苯基二亚胺共聚物表现为近向相和向列相。认为聚（酯-亚胺）比类似的聚（亚胺-碳酸）具有更好的LC性能。

It is known that polymers composed of symmetric aromatic diimides form no liquid crystalline (LC) phases in many cases, but those containing asymmetric diimides have a tendency to show LC melts. In this work, poly(imide-carbonate)s and poly(ester-imide)s, which are constituted of symmetric p-terphenyldiimide and biphenyldiimide units, were prepared and the thermal and mesomorphic properties were investigated in order to disclose the relationship between polymer structures and LC properties. Homo-and copoly(imide-carbonate)s or homo- and copoly(ester-imide)s were synthesized by melt polycondensation of diols of biphenyldiimide and p-terphenyldiimide, which were derived from the corresponding dianhydrides and aminoalcohols, with diphenyl carbonate or diesters of the diimides prepared from aminocarboxylic acids. DSC measurements, polarizing microscope observations of textures, temperature-variable X-ray analyses and miscibility tests showed that the polymers having even methylene chains form enantiotropic LC phases in spite of absence of traditional mesogens such as biphenyl unit. The p-terphenyl-diimide-rich copolymers showed smectic and nematic phases. It is considered that the poly(ester-imide)s have better LC properties than the analogous poly(imide-carbonate)s.