Oligomerization and copolymerization of γ‐butyrolactone — a monomer known as unable to homopolymerize, 1. Copolymerization with ε‐caprolactone

Abstract Copolymerization of γ‐butyrolactone (γBL) with ε‐caprolactone (εCL) initiated with aluminium isopropoxide trimer ([Al(OiPr)3]3, (A3)) is described. Copolymers with molecular weights (Mn) up to 3 · 104 and containing up to 43 mol‐% repeating units derived from γBL are prepared. Their molecular weight is controlled by the concentrations of the consumed comonomers and the starting concentration of initiator {Mn = (86.09 · [γBL]c + 114.14 · [εCL]c)/3[Al(OiPr)3] + 60.10}. 13C NMR and DSC data are indicative of a pseudoperiodic or random copolymer structure.