聚酯酰亚胺共聚物的液晶特性和相转变研究

Studies on the Liquid Crystalline Characters and Phase Transition Behaviors of a Poly(ester imide) Copolymer

利用Higashi芳香聚酯直接缩聚法的原理,采用分步投料溶液共聚合的方法,以N,N′-己二撑-1,6-双苯偏三酸酰亚胺二酸(IA6)、对羟基苯甲酸(p-HBA)和4,4′-二羟基二苯酮(DHBP)为单体原料,合成了一类聚酯酰亚胺三元共聚物。采用核磁共振(NMR)分析了共聚物的化学结构及组成,并用差热分析(DSC)、偏光显微镜(PLM)、广角X射线衍射(WAXD)对聚合物在熔融过程中的相转变及其液晶特性进行了研究。结果表明,由合适的单体组成比合成的共聚物在升温过程中呈现明显的向列型热致液晶特性,在降温过程中则未观察到液晶的相转变。各种分析手段的结果表明,DSC和WAXD的测试结果与在偏光显微镜下观察到的共聚物在熔融过程中所呈现的相转变行为相吻合。

Based on the developed Higashi＇s direct polycondensation method, a poly （ester imide） （PEIs） copolymer derived from N, N＇-hexane-1, 6-diylbis （trimellitimide）, 4, 4＇-dihydroxybenzo-phenone and p-hydroxybenzoic acid （HBA） was synthesized by a ＂step-feeding＂ polycondensation process. The chemical structure and composition of the copolymers were characterized by nuclear magnetic resonance （NMR）. The phase transition behaviors and liquid crystalline characters were also studied with polarized-light microscopy （PLM）, wide-angle X- ray diffraction （WAXD）, differential scanning calorimetry （DSC）. The results showed that the copolymer possessed a typical nematic thermotropic liquid crystalline character upon heating. However, in the cooling process, the transitions of liquid crystalline phase were not observed. It also shows that, the results of DSC and WAXD all well support the phase transitions observed by PLM upon heating.