Thermostable soluble aromatic poly(amide-imide)s having hexafluoroisopropylidene and ether links in the main chain

An imide-containing dicarboxylic acid, 2,2-bis [4-(4-trimellitimidophenoxy) phenyl]-hexafluoropropane (I), was prepared by the condensation of 2,2-bis[ 4-(4-aminophenoxy)phenyl]-hexafluoropropane and trimellitic anhydride. A se ries of new hexafluoroisopropylidene-containing poly(amide-imide)s having i nherent viscosities of 0.64-1.44 dL/g were prepared by the direct polyconde nsation of diimide-diacid I with various long-chain aromatic diamines using triphenyl phosphite and pyridine as condensing agents in N-methyl-2-pyrrol idone in the presence of calcium chloride. Most of the resulting poly(amide -imide)s were noncrystalline and showed good solubility in polar organic so lvents. Almost all polymers afforded transparent, flexible, and tough films . The 10 % weight loss temperatures of these polymers were all above 499 de greesC, and the glass transition temperatures were in the range of 203-277 degreesC.