Development of New Polymeric Matrices for High Performance Composites

High performance monomers based on the precursor trifluoroacetophenone and phenylphosphine oxide have recently been generated. The resulting monomers are important intermediates for a variety of thermally stable polymers such as polyimides and polybenzoxazoles. The pendant aryl group in both systems is nonplanar and affords polymeric systems that are amorphous as well as soluble and processable when end-capped and cyclized in solution. The aryl groups also contribute to excellent thermo-oxidative stability and indeed the systems are comparable to the better known "six F" based systems. The phosphorous containing momoners also cintrobite to high glass transition temperatures, processability and flame resistance. The synthesis and characterization of processable aromatic polyimides and polybenzoxazoles are reported. Glass transition temperatures of 420 deg C have been achieved with polyimide derived for the 3F diamine and pyromellitic dianhydride. The 4-BDAF monomer has been used to obtain semicrystalline polyimides. Fully cyclodehydrated isotropic polybenzoxazoles have also been prepared by an acid catalyzed reaction in o-dichlorobenzene at only 170 deg C. The resulting materials show excellent thermo-oxidative stability and solubility in N-methylpyrrolidinone. These materials are candidates for matrix resin and structural adhesive applications. An overview of the synthesis and characterization of these materials is provided.