二维有序PPTA冻胶体结构及其相转变

STRUCTURE OF TWO DIMENSION ORDERED PPTA GEL AND ITS PHASE TRANSFORMATION

在N—甲基吡咯烷酮、氯化钙溶剂体系中缩聚合成PPTA,当聚合反应达到一定程度时就会出现液晶态,并形成冻胶体,如果停止搅拌,PPTA冻胶体内保留这种液晶状态。用偏光显微镜观察,无论是在垂直于或平行于搅拌方向,都呈现出向列型液晶态所特有的织态结构,显示二维有序结构,这在X—光衍射图谱上反映出来。PPTA液晶冻胶体是一种不稳定的相态,从二维有序的冻胶向三维有序结晶转变,其相转变可在X—光衍射图上表现出衍射峰的裂解。

In the process of formation of PPTA by polymerization in a solvent system of N—methyl pyrrolidon (NMP) and calcium chloride. Liquid crystal appears and gel is formed when polymerization proceeds to a certain extent. Such a liquid crystal state remains in PPTA gel on stopping agitation. Polarizer shows that there exists a texture of orientated schlieren in both parallel and perpendicular to stirring direction, showing a two-dimension ordered structure, which is also manifested by X-ray diffraction. PPTA liquid crystal gel is an unstable phase, undergoing a transformation from two-dimension-alordered gel to three-dimension ordered crystal, which can be shown as the splitting of peaks in X-ray diffraction.