Synthesis and characterization of poly(amide-imide)s derived from a new ortho-functional unsymmetrical dicarboxylic acid

A new diacid monomer containing an imide ring and a methoxy pendant group, 3-trimellitimido-4-methoxybenzoic acid TMBA, was synthesized and characterized. The diacid was used to synthesize six novel poly(amide-imide) s, (PAIs), through a polycondensation reaction with different diamines in the presence of triphenylphosphite, calcium chloride, and pyridine in N-methyl-2-pyrrolidinone. The chemical structures of the diacid monomer and poly(amide-imide) s were confirmed by FTIR and H-1 NMR spectroscopy. All PAIs were obtained in high yield with inherent viscosities ranging from 0.32 to 0.54 dL g(-1). They were soluble in aprotic solvents, and exhibited film forming ability. The PAI films displayed glass transition temperatures between 281 and 377 degrees C, as determined by dynamic mechanical analysis, and they show high thermal stability. Gas permeability results for TMBA-6FDA film show that this PAI could be an interesting material for polymeric membranes aimed to CO2 separation process.