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, PAIh‐h‐t‐t containing alternating (amide–amide)–(imide–imide) sequences and PAIh‐t containing amide–imide sequences could be obtained through direct polycondensation. Comparison of PAIh‐h‐t‐t and PAIh‐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 PAIh‐h‐t‐t possessed larger initial modulus but smaller elongation at break than series PAIh‐t. For the thermal properties, most of series PAIh‐t had glass transition temperatures higher than corresponding series PAIh‐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