Synthesis and characterization of phthalazinone containing poly(arylene ether)s via a novel N-C coupling reaction

High-molecular-weight poly(phthalazinone)s with very high glass-transition temperatures (T_g's) were synthesized via a novel N-C coupling reaction. New bisphthalazinone monomers (7a-e) were synthesized from 2-(4-chlorobenzoyl) phthalic acid in two steps. Poly(phthalazinone)s, having inherent viscosities in the range of 0.34-0.91 dL/g, were prepared by the reaction of the bis(phthalazinone) monomers with an activated aryl halide in a dipolar aprotic solvent in the presence of potassium carbonate. The poly(phthalazinone)s exhibited T_g's greater than 230°C. polymer 8b synthesized from diphenyl biphenol and bis(4-flurophenyl) sulfone demonstrated the highest T_g of 297°C. Thermal stabilities of the poly(phthalazinone)s were determined by thermogravimetric analysis. All the poly(phthalazinone)s showed a similar pattern of decomposition with no weight loss below 450°C in nitrogen. The temperatures of 5% weight loss were observed to be about 500°C. The poly(phthalazinone)s containing 4,4′-isopropylidenediphenol and 4,4′-(hexafluoroisopropylidene) diphenol and diphenyl ether linkage were soluble in chlorinated solvents such as chloroform. Other poly(phthalazinone)s were soluble in dipolar aprotic solvents such as N,N′-dimethylacetamide. The soluble poly(phthalazinone)s can be cast as flexible films from solution.