SYNTHESIS AND CHARACTERIZATION OF N-PHENYLATED WHOLLY AROMATIC NONCYCLIC POLYIMIDES FROM N,N'-DIPHENYLPHTHALIMIDOYL CHLORIDES AND PHTHALIC ACIDS

A novel class of polyimides, N-phenylated wholly aromatic non-cyclic p olyimides, was synthesized by the low-temperature solution and two-pha se phase-transfer catalyzed polycondensations of new aromatic bis(imid oyl chloride)s, N,N'-diphenylisophthalimidoyl chloride and N,N'-diphen ylterephthalimidoyl chloride, with aromatic dicarboxylic acids, isopht halic acid and terephthalic acid. The resulting polyimides were all wh ite in color and had reduced viscosities of 0.11-0.14 dl g-1. Compared with the conventional polyimides having cyclic imide structures, thes e N-phenylated non-cyclic polyimides exhibited better solubility in va rious organic solvents, reduced crystallinity and lower glass transiti on temperatures and thermal stability. The reduced viscosity of a typi cal polyimide decreased rapidly upon UV light irradiation, indicating the occurrence of photodegradation. Before the polymer synthesis, the effects of reaction medium, organic and inorganic bases and phase-tran sfer catalyst were studied on the solution and two-phase reactions of N,N'-diphenylisophthalimidoyl chloride with benzoic acid.