Preparation and properties of new aromatic polyamides from bis(4‐aminophenyl) phenylphosphine and aromatic dicarboxylic acids

A new triphenylphosphine‐type monomer, bis(4‐aminophenyl) phenylphosphine, was synthesized starting from p‐bromoaniline and dichlorophenylphosphine. The aromatic polyamides (aramids) containing triphenyphosphine unit in the polymer backbone was prepared by the polycondensation of this diamine with various aromatic diacid chlorides using a low‐temperature solution method in N,N‐dimethylacetamide (DMAc). The aramids having inherent viscosities of 0.4–0.7 dL/g were obtained in quantitative yields. The polymers were amorphous and soluble in various organic solvents such as DMAc, N‐methylpyrrolidone, dimethyl sulfoxide, pyridine, and m‐cresol. Transparent, tough, and flexible films were obtained by casting from the DMAc solutions. The glass transition temperatures of the aramids were in the range of 265–310°C, and the 10% weight loss temperatures were above 400°C in air.