Synthesis of polyamides by ring‐opening polyaddition of bis‐3,1‐benzoxazin‐4‐ones with aliphatic diamines

Open‐chain polyamides with inherent viscosities of 0.1–0.6 were prepared in nearly quantitative yields by the ring‐opening polyaddition of combinations of six bis‐3,1‐benzoxazin‐4‐one monomers and two aliphatic diamines in polar aprotic solvents at 80°C or below. The polymerization carried out in dimethyl sulfoxide at 80°C was best for preparing high‐molecular‐weight polymers. These polyamides were generally soluble in polar aprotic solvents, m‐cresol, and pyridine.