Copolymerization of Cyclic Esters at the Living Polymer‐Monomer Equilibrium

This paper gives a short review of our findings related to the copolymerization of γ‐butyrolactone ( B ) and L,L ‐lactide ( L ) with ϵ‐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.