Copolymerization of cyclic esters at the living polymer-monomer equilibrium

This paper gives a short review of our findings related to the copolymerization of gamma-butyrolactone (B) and L,L-lactide (L) with epsilon-caprolactone (C) at or below B and L equilibrium concentrations in homopolymerization. We show, contrary to the commonly established opinions, that: (i) B effectively undergoes ring-opening reaction and therefore is able to high molar copolymers formation containing up to 50 mol-% repeating units derived from B and (ii) in conditions eliminating transesterification living poly(L) does initiate polymerization of C leading to poly(L)-block-poly(C) copolymer.