Facile Tandem Copolymerization of O -Carboxyanhydrides and Epoxides to Synthesize Functionalized Poly(ester- b -carbonates).

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 CO 2 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 CO 2 . 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.