Polymerization of lactams: 97. Anionic polymerization of ε-caprolactam activated by esters

The anionic polymerization of ε-caprolactam initiated with 0.5 mol % ethyl magnesium bromide in the presence of cycloaliphatic esters (lactones), such as γ-butyrolactone, δ-valerolactone and ε-caprolactone, has been studied in the temperature range 150–190 °C and concentration up to 5 mol %. To explain reaction mechanism, the polymerizations carried out in the presence n-butyl acetate and dimethyl terephthalate were also evaluated. The apparent rate constants and apparent activation energies were determined for the initial stage of polymerization. The non-integer orders of the polyreaction with respect to the concentration of lactone introduced indicated complex polymerization mechanism.