Aromatic polyethers, polysulfones, and polyketones as laminating resins. VI. Polymers from 2,5‐dicyanoterephthalic acid

Aromatic poly(keto ether sulfones) containing various amounts of pendant cyano groups were synthesized from 1,4‐bis(p‐phenoxybenzoyl)‐2,5‐dicyanobenzene, 1,3‐bis(p‐phenoxybenzenesulfonyl)benzene, and isophthaloyl chloride by a Friedel‐Crafts type polymerization. These polymers softened at 160–190°C and had inherent viscosities of 0.44–0.61 in hexamethylphosphoric triamide. Crosslinkings were made by heating the polymers alone or in the presence of zinc chloride at 360–370°C to give black resinous materials that were insoluble in hexamethylphosphoric triamide in which the original polymers dissolved quite readily.