NHC-Metal Complexes as Catalytic Platforms for the Synthesis and Recycling of Renewable Polymers

In this work, we discuss the results obtained with a class of zinc and magnesium complexes supported by N-Heterocyclic Carbene (NHC) ligands (Figure 1), as tunable catalytic platforms for Ring-Opening Polymerization (ROP) of cyclic esters and carbonates. These catalysts demonstrate excellent control over the polymerization of a range of monomers, mainly derived from sustainable sources, such as carbohydrates and CO₂. Beyond aliphatic polyesters and polycarbonates synthesis, the catalytic systems exhibit remarkable versatility, enabling the formation of ester/carbonate copolymers and promoting the methanolysis of polylactide (PLA), thus contributing to the realization of a fully circular polymer lifecycle. The effect of substituents and backbone of the NHC ligands on the catalytic behavior is also discussed.