Synthesis and Characterization of New Aromatic Poly(amide-imide)s Derived from Bis(3-trimellitimidophenyl) Phenyl Phosphine Oxide and Various Aromatic Diamines

New aromatic poly(amide-imide)s with high inherent viscosities were prepared by direct polycondensation reaction of diimide-diacid (I) and aromatic diamines using triphenyl phosphite in N-methyl-2-pyrrolidone (NMP)/pyridine solution containing dissolved CaCl2. The bis(3-trimellitimidophenyl) phenyl phosphine oxide (I) was readily obtained by the condensation reaction of bis(3-aminophenyl) phenyl phosphine oxide (BAPPO) with trimellitic anhydride. The resulting poly(amide-imide)s showed high thermostability. Their decomposition temperatures at 10% weight loss in nitrogen atmosphere were above 532 ºC and the anaerobic char yield at 800 ºC ranged from 56% to 74%. Almost all the poly(amide-imide)s showed high glass transition temperature above 233 ºC by differential scanning calorimetry (DSC) measurements. These polymers were readily soluble in various organic solvents and by their casting into transparent, tough and flexible films can be easily achieved