Anionic copolymerization of ω-lactams with ω-lactones

Copolymerizations of e-caprolactam, α-pyrrolidone or α-piperidone with e-caprolactone or δ-valerolactone have been carried out in the presence of alkali metal. It has been shown that in copolymerizations of e-caprolactam or α-pyrrolidone with e-caprolactone and α-pyrrolidone with δ-valerolactone conversions of above 70 % and reduced viscosities of above 0.5 in m-cresol at 35°C for all compositions were obtained. In the case of copolymerization of e-caprolactam with δ-valerolactone at 180°C a conversion of 25 % and a reduced viscosity of 0.5 were obtained, but the polymer was polycaproamide, while at 90°C the conversion was 50 % but the polymer was polyvalerolactone. In copolymerizations of α-piperidone with e-caprolactone or δ-valerolactone the copolymer contained only polyester. A mechanism is proposed for the copolymerization of ω-lactams with ω-lactones with alkali metal, which involves chain propagation by the stepwise addition of the lactam ring at an end of the chain molecule and by the stepwise addition of the lactone ring at the other end of the chain molecule, resulting to a certain extent in the formation of polyester and polyamide segments. This mechanism is supported by experimental results obtained through the reaction in the presence of alkali metal salts of ω-lactam, data on infrared analyses and elementary analyses, and by experimental results obtained through measurements of physical properties of these copolymers.