High‐molecular‐weight polyterephthalamide by direct polycondensation reaction in the presence of poly(ethylene oxide)

Polyterephthalamides of high molecular weight (ηinh up to 1.9) were obtained by the direct polycondensation reaction of terephthalic acid and aromatic diamines in the presence of poly(ethylene oxide) (PEO) with triphenyl phosphite in a N‐methylpyrrolidone (NMP)–pyridine solution that contained lithium chloride. The molecular weights of the polymers produced varied with the amount and molecular weight of PEO, which showed maximum values when PEO with a molecular weight of 2.0 × 104−5.0 × 105 was used in a concentration of about 0.5 wt % in the solvent. The polycondensation reaction was significantly affected by the level of pyridine in a mixed solvent of NMP and pyridine and by the concentration of the lithium chloride added.