Ring-opening (co)polymerization of γ-butyrolactone: a review

With increased environmental concerns and the rising demands for sustainable polymers, e.g., degradable polymers and chemically recyclable polymers, studies on ring-opening polymerization (ROP) of cyclic esters have been developed in recent decades. Biorenewable five-membered gamma-butyrolactone (gamma BL) may be a desirable feedstock for the chemical synthesis of poly(gamma-butyrolactone) (P gamma BL) or for the incorporation of gamma BL units into polyester chains to modify their properties. Although gamma BL is traditionally considered to be "nonpolymerizable", some progress was recently made concerning the ROP of gamma BL. This mini-review is thus specifically focused on the ROP of gamma BL and its copolymerization with other cyclic esters.