Synthesis of hydrolytically stable phosphorus-containing polymers via polycondensation and their utilization in polymer blends

Amorphous polyarylene ether homo- and copolymers were synthesized which were based upon bisphenol A and either 4, 4'-dichlorodiphenylsulfone, 4, 4'-difluorobenzophenone or 4, 4'-difluorodiphenyl phenylphosphine oxide. Solution blends were prepared from these homo- and copolymers with linear bisphenol A based polyhydroxyether, which was used as a model for the epoxy or vinyl ester thermosetting matrix resins for composite materials. It was observed that transparent, single Tg blends could be prepared from the phosphine oxide containing homopolymer and a 50/50 phosphine oxide/dichlorodiphenylsulfone copolymer. The other homopolymers produced materials with two Tg's, implying that they were definitely phase separated systems. Thermogravimetric analysis was also conducted and the phosphine oxide blends produced high char yields suggesting utilization in fire-resistant applications. The miscibility of the phosphine oxide material has been attributed to specific hydrogen bonding interactions observed between the phosphine oxide bond and the secondary hydroxyl group in the polyhydroxy ether. This hydroxyl functionality is also present in the epoxy and vinylester precursors and it is suggested that these materials could be utilized as interface sizings for carbon fibers, which would produce a graded microstructure between the fiber and the polymer matrix systems.