Direct synthesis of soluble and thermally stable poly(urethane-imide)s from a new triimide–dicarbonylazide

A new aromatic dicarbonylazide (3) bearing three preformed imide rings was synthesized by treating N-[3,5-bis(trimellitimido)phenyl]phthalimide (1) with thionyl chloride followed by a nucleophilic reaction with sodium azide. A novel family of fully aromatic poly(urethane-imide)s with inherent viscosities of 0.19–0.24 dl g−1 were prepared from triimide–dicarbonylazide 3 and various aromatic diols. The polyaddition reactions readily proceeded in desirable yields as one-pot reactions starting from 3 without separately synthesis of the corresponding diisocyanate. All of the resulted polymers were thoroughly characterized by spectroscopic methods and elemental analyses. The poly(urethane-imide)s exhibited an excellent solubility in a variety of polar solvents. Crystallinity nature of the polymers was estimated by means of WXRD. The glass transition temperatures of the polymers determined by DSC method were in the range of 197–219 °C. The 10% weight loss temperatures of the poly(urethane-imide)s from their TGA/DTG curves were found to be in the range of 391–412 °C in nitrogen. The films of the polymers were also prepared by casting the solution.