Preparation of poly(amide‐imide)s by means of triphenyl phosphite, 1. Aliphatic‐aromatic poly(amide‐imide)s based on trimellitimide

Aliphatic‐aromatic poly(amide‐imide)s with high molecular weight (ηinh up to 2,91 dl/g in DMAc/5% LiCl) were synthesized by direct polycondensation reaction of imide‐containing dicarboxylic acids and aromatic diamines using triphenyl phosphite in N‐methyl‐2‐pyrrolidone (NMP)/pyridine solution in the presence of metal salts. The factors affecting the reaction of N‐(trimellitoyl)glycine and 4,4′‐oxydianiline were investigated. The molecular weight of the polymer varied with the amount of metal salts, showing a maximum at a concentration of about 1 wt.‐% CaCl2 or about 2 wt.‐% LiCl in the reaction mixture. A monomer concentration of about 0,2 mol/l gave the most favorable result. Among the solvents tested, NMP was most effective. Similarly, polycondensations of several combinations of three imide‐diacids with various aromatic diamines were carried out. Solubility, thermal properties, and tensile properties of the polymers are discussed.