A new-type of tetraimide-dicarboxylic acid (I) was synthesized starting from ring-opening addition of p-aminobenzoic acid (p-ABA), 4,4'-oxydiphthalic anhydride (ODPA) and 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) at a 2:2:1 molar ratio in N-methyl-2-pyrrolidone (NMP), followed by cyclodehydration to the diacid I. A series of poly(amide-imide-imide)s (IIIa-i) with inherent viscosities of 0.82-1.20 dl g(-1) was prepared by triphenyl phosphite-activated polycondensation from the tetraimide-diacid (I) with various aromatic diamines (IIa-i) in a medium consisting of NMP, pyridine, and calcium chloride. Most of the polymers were readily soluble in a variety of organic solvents such as NMP, NN-dimethyl acetamide (DMAc), dimethyl sulfoxide (DMSO), and even in less polar in-cresol. In comparison with corresponding poly(amide-imide)s (IVa-i), the solubilities of poly(amide-imide-imide)s (IIIa-i) were largely improved. Most of the polymers (III) afforded tough, transparent, and flexible films, which had tensile strengths ranging from 96 to 107 MPa, elongations at break from 9 to 16%, and initial moduli from 2.0 to 2.3 GPa. The glass transition temperatures of polymers recorded at 257-278 degreesC. They had 10% weight loss temperature above 540 degreesC and left more than 46% residue even at 800 degreesC in nitrogen. (C) 2002 Elsevier Science B.V. All rights reserved.