New poly(amide‐imide)s synthesis, 16 . Preparation and properties of poly(amide‐imide)s derived from 3,3‐bis[4‐(4‐aminophenoxy) phenyl]phthalide and various bis(trimellitimide)s

A series of novel bis(phenoxy)phthalide‐containing poly(amide‐imide)s 3 were synthesized via direct polycondensation of 3,3‐bis[4‐(4‐aminophenoxy)phenyl]phthalide (BAPP) with various aromatic bis(trimellitimide)s 2 in N ‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. Poly(amide‐imide)s 3 having inherent viscosities up to 1,68 dL/g were obtained in quantitative yields. Most of the resulting polymers showed an amorphous nature and were readily soluble in polar solvents such as NMP and N , N ‐dimethylacetamide. All the soluble poly(amide‐imide)s afforded transparent, flexible, and tough films. The glass transition temperatures of these polymers were in the range of 237–292°C and the 10% weight loss temperatures were above 500°C in nitrogen. The properties of poly(amide‐imide)s 3 were compared with those of the corresponding isomeric poly(amide‐imide)s 3′ prepared from 3,3‐[4‐(4‐trimellitimido‐phenoxy)phenyl]‐phthalide and various aromatic diamines.