Facile Tandem Copolymerization of O-Carboxyanhydrides and Epoxides to Synthesize Functionalized...

The synthesis of well-defined degradable block copolymers from mixtures of monomers is one of the foremost challenges in the sustainable plastics industry. For example, the currently available one-pot strategies for preparing poly(ester-co-carbonates)─which combine two commonly used degradable polymers─are energy- and material-intensive, requiring high-pressure CO₂ gas and elevated temperatures. Here, we report an atom-economical, scalable method for block copolymerization of O-carboxyanhydrides (OCAs) and epoxides to prepare functionalized poly(ester-b-carbonates) with high molecular weights (MWs) (>200 kDa) and narrow MW distributions (D̵ < 1.1) by using a single Lewis acidic zinc complex at room temperature in the absence of pressurized CO₂. Kinetic studies showed that the first stage of the process, ring-opening polymerization of the OCAs, exhibited zero-order kinetics, suggesting that the polymerization rate was independent of monomer concentration and thus allowing for a sharp switch in mechanism without the tapering effect. The obtained degradable poly(ester-b-carbonates) showed better toughness than their corresponding homopolymers and outperformed some commodity polyolefins.