AROMATIC POLYAMIDES WITH PENDENT HETEROCYCLES .2. BENZOXAZOLE GROUPS

A series of polyisophthalamides (PIPAs) containing pendent benzoxazole groups was prepared from six aromatic diamines and a new monomer, 5-( 2-benzoxazole)isophthaloyl chloride. These polymers, having moderate t o high inherent viscosity values, were synthesized by the low temperat ure polycondensation method in high yields. A striking feature of thes e polymers is that their solubility and thermal properties were enhanc ed compared to the corresponding unmodified PIPAs. Thus, all of the po lymers were soluble in aprotic polar solvents and glass transition and decomposition temperatures were, respectively, 15-40-degrees-C and 25 -35-degrees-C higher than for the reference PIPAs. The tensile strengt hs were somewhat lower than those for the unmodified PIPAs.