Thermally stable and organosoluble poly(amide-imide)s based on the imide ring-preformed dicarboxylic acids derived from 3,4′-oxydianiline with trimellitic anhydride and 6FDA

A diimide-dicarboxylic acid (DIDA) (I) was prepared from the condensation reaction of trimellitic anhydride (TMA) and 3,4′-oxydianiline (3,4′-ODA) in a 2:1 molar ratio, and another new tetraimide-dicarboxylic acid (TIDA) (II) was synthesized by condensation from 4,4′-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), TMA, and 3,4′-ODA in a 1:2:2 molar ratio. Two series of aromatic poly(amide-imide)s (PAI) IVa-k and Va-k were synthesized by Yamazaki phosphorylation polyamidation reactions of DIDA I and TIDA II, respectively, with various aromatic diamines. Due to highly random segmental sequence for both series in the polymer chain and the incorporation of 6FDA moieties for the V series, all the polymers were readily soluble in many organic solvents and could be casted into transparent, flexible, and tough films with good mechanical properties. Glass-transition temperature (T_gs) of the IV series and V series were recorded in the range of 242–274°C and 264–295°C. In addition, almost all the polymers showed 10% weight loss temperatures higher than 500°C under a nitrogen or an air atmosphere.