Preparation of organo-soluble co-polyimides using N -methyl-2-pyrrolidone as the solvent via one-pot high-temperature polymerization

A series of organo-soluble co-polyimides (co-PIs) were successfully synthesized from 3,3′,4,4′-benzophenonetetracarboxylic-dianhydride (BTDA), 1,4-bis-(4-amino-2-trifluoromethyl-phemoxy)-benzene (p-6FAPB) and 2-(4-aminophenyl)-5-aminobenzimidazole (BIA) via the one-pot high-temperature polymerization using N-methyl-2-pyrrolidone (NMP) as the solvent. The imidization reaction of poly(amic acid)s in solution state was discussed in detail by attenuated total reflectance-Fourier transform infrared spectra (ATR-FTIR), and the results illustrate that the introduced benzimidazole moiety has a catalytic activity on the imidization process. The number-average molecular weights and polydispersity index of these PIs measured by gel permeation chromatography range from 1.11 × 105 to 2.20 × 105 and 1.82 to 3.84, respectively. The prepared co-PIs exhibit sufficient solubility in some polar solvents and high optical transparency. Meanwhile, these co-PI films show good mechanical performances, and the strength and modulus of the sample with the molar ratio of p-6FAPB/BIA = 5/5 reach 183 MPa and 4.71 GPa, respectively. Moreover, the obtained co-PIs possess high glass transition temperatures (Tg) (above 260 °C) and good thermal stability with 5% weight loss temperature in the range of 502–531 °C in the nitrogen atmosphere. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45497.