New poly(amide-imide)s syntheses. II. Soluble poly(amide-imide)s derived from 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene and various N-(ω-carboxyalkyl)-trimellitimides,N-(carboxyphenyl)trimellitimides,or N,N″-bis(ω-carboxyalkyl)pyromellitimides

Various dicarboxylic acids with preformed imide rings were readily obtained by the condensation of ω-amino acids and aminobenzoic acids with trimellitic anhydride, and omega;-amino acids with pyromellitic dianhydride. New tetraphenylthiophene-containing poly(amide-imide)s having inherent viscosities of 0.58-1.54 dL/g were prepared by the direct polycondensation reaction of 2,5-bis(4-aminophenyl)-3,4-diphenylthiophene with the imide-containing dicarboxylic acids using triphenyl phosphite and pyridine as condensing agents. These polymers were amorphous and readily soluble in a variety of solvents such as dimethylacetamide (DMAc), dimethylformamide (DMF), and N-methyl–2-pyrrolidone (NMP), and could be easily solution cast into transparent, flexible, and tough films. Most of the poly(amide-imide)s showed clear glass transition on the heating traces of differential scanning calorimetry (DSC) in the range of 146–244°C. Almost all the poly(amide-imide)s exhibited no appreciable decomposition below 400°C, with 10% weight loss being recorded above 420°C in nitrogen. © 1992 John Wiley & Sons, Inc.