Chemical modification of copolyimides with bulky pendent groups: Effect of modification on solubility and thermal stability

摘要

Two novel copolyimides bearing bulky pendent groups have been prepared by chemical modification of a copolyimide precursor containing carboxylic acid groups. The incorporation of the bulky groups was achieved by esterification of the copolyimide containing carboxylic acid groups with 4-tert-butylbenzyl alcohol. By controlling the carboxylic acid/alcohol ratio, two different degrees of modification were obtained. The actual composition of the modified polymer was estimated by ~1H NMR. They showed better solubility than the copolyimide precursor, where 100% modification yielded the copolyimide with the highest solubility properties. Thermal analyses indicated that the incorporation of bulky pendent groups has a moderate effect on decreasing the thermal degradation temperature and the glass transition temperature.