Fractionation and crystallization of wholly aromatic rigid polymer

对刚性聚合物聚对苯并双噻唑（PBZT）在稀溶液中进行了分馏。甲烷硫酸用硅胶作为色谱柱填料。研究了分馏材料的平均链长和凝胶的平均孔径的几种组合，以提高分馏分辨率。平均孔径接近平均链长的凝胶具有较高的分馏分辨率。用透射电镜观察了分馏和未分馏PBZT的单晶形貌。这两种单晶基本上都是由棒状晶体组成的，其链与棒状晶体垂直。未分析的PBZT形成了一簇平行的棒状晶体，其中较长的链穿透了一些棒状晶体，使它们的链端留在结晶核心内。相反，在分馏过程中，延伸链棒状晶体分散，彼此隔离。这种形态使我们能够通过透射电镜可见地估计链长，其中几毫克的材料足以观察。

Fractionation of the rigid polymer, poly(p-phenylene benzobisthiazole) (PBZT) was carried out in dilute solution in conc. methane sulfuric acid using silica gels as packing material of a column. Several combinations of the average chain length of the fractionating materials and the average pore diameter of the gels were examined to improve fractionation resolution. The gels with the average pore diameter near to the average chain length resulted in high fractionation resolution. Single crystals of the fractionated and unfractionated PBZT's were observed by TEM. Both single crystals were fundamentally composed of rod crystals with the chain orienting normal to the rods. The unfractionated PBZT made a cluster of parallel rod crystals, where longer chains penetrated a few rod crystals leaving their chain ends within the crystalline core. On the contrary, with the fractionated polymer, extended- chain rod-like crystals were dispersed isolated from each other. This morphology enables us to estimate the chain length visibly by TEM, for which a few milligrams of the material is enough for the observation.