A new class of aromatic poly(urea-imide)s having biphenylene pendant group was prepared by the diphenyl azidophosphate (DPAP) activated one-pot polyaddition reaction of a preformed imide ring-containing dicarboxylic acid, 4-p-biphenyl-2,6-bis(4-trimellitimidophenyl)pyridine (1) with various aromatic diamines. A model compound was also synthesized by the reaction of diimide-dicarboxylic acid I with two mole equivalents of aniline. In this direct method the polymers were prepared by polyaddition reactions of the in situ-formed diisocyanate with the aromatic diamines. The inherent viscosities of the polymers were measured in the range of 0.11-0.15 dL g(-1). The ultraviolet values of the poly(urea-imide)s were also determined. Furthermore, crystallinity of the resultant polymers was evaluated by wide-angle X-ray diffraction method, and they exhibited nearly a noncrystalline nature. All of the resulting polymers exhibited excellent solubility in common polar solvents. The glass transition temperatures of the polymers determined by DSC thermograms were in the range 241-272 degrees C. The temperatures at 10% weight loss from their TGA curves were found to be in the range 406-437 degrees C in nitrogen. (C) 2008 Wiley Periodicals, Inc.