Suspension cross-linking of poly(aryl ether ketone)s containing carboxylicacid functionality

The poly(Friedel-Crafts) reaction between benzene-1,2,4,5-tetracarboxylic d ianhydride and diphenyl ether gave carboxylic acid functional polyarylates (PEKK-COOH) that were soluble in polar solvents such as NMP and DMF. The ca rboxylic acid functional polymers were thermally stable up to 400 degreesC. PEKK-COOHs in DMF or NMP solution, dispersed in paraffin oil, were cross-l inked by reaction of the pendant carboxylic groups with bisphenol-A diglyci dyl ether. Insoluble networks were formed by reaction of between 45 and 95 mol% of the carboxylic acid groups. Although regular particles were formed initially, upon drying they formed irregular particulate aggregates that co uld not be redispersed back to the primary particles. The networks showed a degradative weight loss around 150 degreesC, which was caused by dehydrati on from the 2-hydroxypropyloxy group. Further curing of the particles at 16 0 degreesC produced a material which did not show any obvious differences i n colour or form from the non-heated particles.