Formation of polyimides by ?COOH and ?CN reactions

The synthesis of linear polyimides by the addition of dicarboxylic acids to dinitriles has been investigated. Adipic, suberic, m- and p-phenylenediacetic, isophthalic, and p-cyanobenzoic acids as well as adiponitrile, m- and p-phenylenediacetonitrile, and isophthalonitrile were studied. Fairly favorable results, low molecular weight polymers only, were obtained in the reaction of p-phenylenediacetic acid with p-phenylenediacetonitrile. The formation of polyimides seems to be restricted by the solubilities of the reactants and products as well as by the pK values of the starting dicarboxylic acid and of the acid which is formed.