Synthesis and characterization of two polytrimellitamideimide series with different segment order by direct polycondensation

Poly(amide–imide) (PAI) could be synthesized in regular segment order from trimellitic anhydride (TMA) and various aromatic diamines. By different processes, PAI_{h‐h‐t‐t} containing alternating (amide–amide)–(imide–imide) sequences and PAI_h‐t containing amide–imide sequences could be obtained through direct polycondensation. Comparison of PAI_{h‐h‐t‐t} and PAI_h‐t, which had different sequence orders and were prepared from TMA and 12 diamines, showed that the latter had better solubility and needed less quantity of solvent and salt (CaCl₂) during polymerization, but both two series PAI using p‐substituted diamines (e.g., p‐phenylenediamine) showed poor solubility. Series PAI_{h‐h‐t‐t} possessed larger initial modulus but smaller elongation at break than series PAI_h‐t. For the thermal properties, most of series PAI_h‐t had glass transition temperatures higher than corresponding series PAI_{h‐h‐t‐t}, but these two series were similar in the 10% weight loss temperatures and the char yields at 800°C in nitrogen. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 1556–1567, 2001