Physics Of Solid State Polymerization

固相聚合是一种在本体聚合完成后增加缩聚聚合物相对分子质量的常用技术。固相聚合为获得超高强度、高模数、热稳定性、耐化学性的聚合物提供了最有吸引力的途径之一。该技术涉及在大气中将聚合物加热到观察到的熔融温度约50oC以内，在该气氛中，通过去除低分子量缩合副产物来推动各种分子量构建反应接近完成。固相聚合的化学性质相对较好，但导致热致聚合物拉伸强度极大提高的机理尚未完全阐明。这项工作的目的是为了更好地了解在定向热致聚合物的固态聚合过程中有时会出现的韧性的大幅增加。将合成有助于分析端基聚集、迁移率和反应的特定聚合物，以阐明端基迁移率、反应性或聚集的影响。在固态退火后，将使用固态核磁共振来跟踪末端基团数量及其接近程度的变化。热处理效果将用一些化学和物理技术进行分析。希望这项工作将阐明合成坚硬、坚固、耐化学腐蚀、基本上无缺陷、高介电常数和轻质材料的最佳机制。

Solid state polymerization is a technique commonly employed for increasing the molecular weight of condensation polymers after bulk polymerization has been completed. Solid state polymerization offers one of the most attractive routes for obtaining extremely high strength, high modulus, thermally stable, chemically resistant polymers. The technique involves heating the polymer to within about 50oC of the observed melting temperature in an atmosphere in which various molecular weight building reactions are driven towards completion by the removal of low molecular weight condensation byproducts. The chemistry of solid state polymerization is relatively well understood, the mechanisms responsible for the enormous increase in tensile strength of thermotropic polymers have not been fully elucidated. This work is aimed at obtaining a better understanding of the large increase in tenacity that sometimes occurs during the solid state polymerization of oriented thermotropic polymers. Specific polymers that facilitate analysis of end group clustering, mobility, and reaction will be synthesized in order to elucidate the effect of end group mobility, reactivity, or clustering. The changes in the number of end groups, and their proximity will be followed using solid state NMR after solid state annealing. The effect of heat treatment will be analyzed using some chemical and physical techniques. It is hoped that the work will elucidate the optimal mechanisms for the synthesis of stiff, strong, chemically resistant, essentially defect-free, high dielectric, and lightweight materials.