Ionic graft copolymerization. II. Graft copolymerization of β‐propiolactone onto acrylonitrile–sodium acrylate copolymer

Polyacrylonitrile–β‐propiolactone (βPL) graft copolymer was synthesized by means of ionic polymerization, in which polymerization of βPL was initiated by polyacrylonitrile containing a small amount of some reactive groups such as COOK, COONa, COOLi, and COOH. Lower electronegativity of the countercation favored higher total conversion and higher grafting percentage. The grafting percentage increased with the reaction time and concentration of reactive groups in the trunk polymer, but grafting efficiency varied very little under these conditions. In the bulk polymerization at 60°C., grafting efficiency was about 60%, but in the solution polymerization in toluene or dioxane, grafting efficiency was higher than in bulk or nitrobenzene.