Synthesis and properties of aromatic polyamides of 2,3-bis(4-aminophenoxy)naphthalene

A new polymer‐forming diamine, 2,3‐bis(4‐aminophenoxy)naphthalene, was synthesized in two steps from the condensation of 2,3‐naphthalenediol and p‐chloronitrobenzene, giving 2,3‐bis(4‐nitrophenoxy)naphthalene, followed by the reduction with hydrazine/Pd‐C system. A series of novel aromatic polyamides (aramids) were synthesized by direct polycondensation of the diamine with various aromatic dicarboxylic acids in N‐methyl‐2‐pyrrolidone (NMP) using triphenyl phosphite and pyridine as condensing agents. These aramids have inherent viscosities of 0,70–1,48 dL/g and were obtained in quantitative yield. The polymers are generally soluble in a wide range of solvents, such as N,N‐dimethylacetamide, NMP, dimethyl sulfoxide, pyridine, and tetrahydrofuran, and afford transparent, flexible, and tough films upon casting from their solutions. The glass transition temperatures of these aramids are in the range of 242−267°C, and the 10% weight loss temperatures are above 503°C in nitrogen and above 496°C in air.