An imide ring-containing dicarboxylic acid, 2,7-bis[4-(N-trimellitoyl)phenoxy]naphthalene (1,1',3,3'-tetraoxo-2,2'-[2,7-naphthylenedioxybis(1,4-phenylene)]di-1H,3H-isoindole-5-carboxylic acid (3)), was prepared by condensation of 2,7-bis(4-aminophenoxy)naphthalene (4,4'-(2,7-naphthylenedioxy)dianiline) and trimellitic anhydride (1,2,4-benzenetricarboxylic acid 1,2-anhydride). A series of new aromatic poly(amide-imide)s 5 containing bis(phenoxy)naphthalene moieties having inherent viscosities of 0,8 - 1,57 dL/g were prepared by direct polycondensation of this diimide-diacid 3 with various aromatic diamines using triphenyl phosphite and pyridine as condensing agents in 1-methyl-2-pyrrolidone (NMP) in the presence of calcium dichloride. Polymers 5 show excellent solubility in polar solvents such as NMP. and most of them could be cast into transparent and tough films. Measurements of wide-angle X-ray diffraction revealed that those polymer containing p-phenylene or oxyphenylene groups are partially crystalline. Amorphous members exhibit glass transition temperatures in the range of 250 - 311-degrees-C. Thermal analyses indicated that these polymers are fairly stable, and the 10% weight loss temperatures were recorded in the ranges of 526 - 575-degrees-C in nitrogen and 481 - 556-degrees-C in air.
