Biphenylene as a crosslinking unit in polyaromatic ether–ketone and ether–ketone–sulfone resins. XVI

Biphenylene units have been incorporated into polyaromatic ether–ketone and polyaromatic ether–ketone–sulfone resins as useful crosslinking sites. Crosslinking is achieved by heating the resins to 300–400°C. The keto polymers are soluble only in sulfuric acid before curing, but the sulfone polymers are soluble also in some aprotic solvents. Molded “I beams” of the cured keto polymer are stronger than those of the sulfone polymer. Both classes of polymer are quite thermally stable. Curing can be hastened by catalyzing with rhodium compounds.