Syntheses of soluble tert-butyl substituted poly(p-oxybenzoate)s

Soluble poly(p-oxybenzoate)s (POBs) were synthesized by direct solution pol ycondensation using thionyl chloride and pyridine as condensation agents st arting from tert-butyl substituted p-hydroxybenzoic acids (3-tert-butyl-4-h ydroxybenzoic acid (BuHB) and 3,5-di-tert-butyl-4-hydroxybenzoic acid (Bu2H B)). Tert-butyl substituted homopolymers (homo-POBs) had poor solubility in organic solvents, whereas solubility of resulting copolymers (co-POBs) was improved in comparison with that of homo-POBs. In particular, the co-POBs with the weight average molecular weight (M-w) value of 20 000 from BuHB/Bu 2HB in the monomer feed ratio of 40/60-50/50 were soluble in various organi c solvents such as tetrahydrofuran, chloroform, N, N-dimethylformamide, and 10 wt% loss and glass transition temperatures of co-POBs in nitrogen were at 375 degrees C and 190 degrees C, respectively.