writer：Lei Li, Xiao-dong Zhao, Jing-lun Zhou, Xing-he Fan
keywords：Polybenzoxazole, Precursor, Hydroxy-substituted Polyenaminonitrile, Cyclization
source：期刊

Aromatic polybenzoxazole (PBO) precursor, hydroxy-substituted polyenaminonitrile, was prepared by direct polycondensation of 1,4-bis(1-chloro-2,2-dicyanovinyl)benzene (CCB) and 4,6-diaminoresorcinol dihydrochloride (DAR) using pyridine and N,N-dimethylacetamide as condensing agent and solvent. The precursor has good solubility in polar aprotic solvent which is due to the strong dipolar nature of the main chain. The soluble precursor was subjected to thermal cyclization in an inert atmosphere to convert it into the corresponding PBO, which has its 5% weight loss temperature at 540 ⁰C.The fully cyclized PBO were characterized by FT-IR and TGA. The introduction of 10% mol 1,3,5-benzenetricarboxylic chloride (BTC) into the main chain not only has little effect on the solubility of PBO precursor but also raises its 5% weight loss temperature to 552°C and char yield at 700°C for the cyclized PBO with BTC