Synthesis and characterization of novel aromatic polyamides and polyimides derived from 2,3-di(3-aminophenyl)quinoxaline

A novel aromatic diamine 2,3-di(3-aminophenyl)quinoxaline (DAPQ) was prepared from benzil through three steps. New aromatic polyamides were synthesized by the direct polycondensation of DAPQ and several aromatic dicarboxylic acids. The polyamides were obtained almost quantitatively. The inherent viscosities ranged from 0.49 to 0.56 dl g(-1). The glass transition temperatures (T(g)s) of the polyamides ranged from 258 to 291 degrees C, and the temperatures at 10% weight loss (T(d10)s) ranged between 515 and 546 degrees C. Novel aromatic polyimides were synthesized by the ring-opening polyaddition of several aromatic tetracarboxylic dianhydrides to DAPQ, followed by thermal cyclodehydration. The polyamic acids indicated the inherent viscosities of 0.28-1.13 dl g(-1). T(g)s of the polyimides ranged between 263 and 298 degrees C, and T(d10)s were above 550 degrees C. The polyamides and polyimides were soluble in several organic solvents such as m-cresol.