New processable polyaromatic ether–keto‐sulfones curable by Diels‐Alder cycloaddition

New Processable polyaromatic ether‐keto‐sulfones were prepared from the acid chloride of bis‐ m ‐carboxyphenyl acetylene (XII), isophthaloyl chloride (XX), diphenyl ether (XVIII), and 4,4′‐diphenoxydiphenyl sulfone (XIX) in a Friedel‐Crafts‐type polymerization. These polymers were cured by Diels‐Alder cycloaddition with 1,4‐diphenyl‐1,3‐butadiene. The cured polymers showed an increase in T g and in thermal and heat stabilities. The polymers form colorless, transparent, brittle films and can be cast into a glass fiber laminate. Both meta‐and para‐substituted acid chlorides of biscarboxyphenyl‐1,3‐butadiene yielded insoluble polymers under the same conditions but form processable polymers where combined with acetylene units in the polymer chain. Polymers that contained both acetylene and butadiene units were prepared but could not be cured by an intramolecular Diels‐Alder cycloaddition reaction.