Ring‐opening polymerization of l‐lactide in the presence of α‐hydroxy‐γ‐butyrolactone

Abstract

Among the polymer families, aliphatic polyesters stand out from this category thanks to their degradable and biocompatible properties. In particular, the γ‐lactones differ from other lactones by yielding polyesters that can be depolymerized back to the monomer and offer the advantage of counting various biobased monomers. As an example, α‐hydroxy‐γ‐butyrolactone (HBL) is a hydroxy‐functionalized monomer that can be obtained by a biological synthetic route from glucose. In this article, the ring‐opening copolymerization (ROCP) of HBL and l‐lactide (LLA) using t‐BuP4 as catalyst is investigated. The copolymerizations were conducted within a temperature range of 5–100°C, affording monomer conversions exceeding 80%. The characterization of the copolyesters revealed a branched structure consisting of different HBL patterns, including cyclic, linear, and branched motives. Performing a kinetic study of the copolymerization at room temperature provided a deeper understanding of the mechanism. By modulating the reaction parameters, copolymers of low molar masses with an HBL content of up to 33% were synthesized. High molar mass LLA/HBL‐based copolyesters, with up to 290,000 g/mol, were synthesized by a straightforward chain coupling reaction with a diisocyanate.