AROMATIC POLYAMIDE-IMIDES AS MATERIALS FOR MEMBRANES .1. SYNTHESIS AND CHARACTERIZATION

Diamine amic acids were synthesized by reacting aromatic diamines with pyromellitic dianhydride in dimethylacetamide/dioxane. High molecular weight polyamide-amic acids were prepared by low-temperature solution polymerization of diamine amic acids with isophthaloyl chloride in di methylacetamide. The cyclodehydration of polyamide-amic acids to the c orresponding polyamide-imides was accomplished by heating the cast fil ms at 175 degrees C for 3 h. The polyamide-imides were soluble in pola r aprotic solvents like dimethylformamide, dimethylacetamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone and could be cast into tough an d flexible films. They were characterized by elemental analyses, inher ent viscosities, IR, and H-1-NMR spectra. The glass transition tempera tures of polyamide-imides were determined by differential scanning cal orimetry. The thermal stabilities of the polymers were measured by the rmogravimetric analyses in air. (C) 1995 John Wiley & Sons, Inc.