ABSTRACT: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 0.56dl g-1 .The glass transition temperatures (T.s) of the polyamides ranged from 258 to 291 °C, and the temperatures at 10% weight loss (Td 10 s) ranged between 515 and 546°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 dlg-1 . T.s of the polyimides ranged between 263 and 298°C, and Td 10s were above 550°C. The polyamides and polyimides were soluble in several organic solvents such as m-cresol.

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ABSTRACT:The direct polycondensation of racemic lactic acid using condensing agents, such as 1, 1' -carbonyldiimidazole (CDI), N,N,N',N' -tetrametbylchloroformamidinium chloride (TMCF AC), and N,N' -dicyclohexylcarbodiimide/4-dimethylaminopyridine (DCC(DMAP), was investigated. Reactions using CDI proceeded slightly. Polycondensation using TMCFAC with pyridine gave a polymer in 83% yield, but the number-average molecular weight (.M.) was 3700. Thus, TMCFAC is not effective in the direct polycondensation of lactic acid. However, DCC/DMAP is effective, and polycondensation in dichloromethane at room temperature for 24h afforded poly(lactic acid) having M. of 15400 in 89% yield.

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