Living Coordination Polymerization of a Six-Five Bicyclic Lactone to Produce Completely Recyclable Polyester

The development of chemically recyclable polymers promises a closed-loop approach towards a circular plastic economy but still faces challenges in structure/property diversity and depolymerization selectivity. Here we report the first successful coordination ring-opening polymerization of 4,5-trans-cyclohexyl-fused γ-butyrolactone (M1) with lanthanide catalysts at room temperature, producing P(M1) with M_n up to 89 kg mol^-1 , high thermal stability, and a linear or cyclic topology. The same catalyst also catalyses selective depolymerization of P(M1) back to M1 exclusively at 120 °C. This coordination polymerization is also living, enabling the synthesis of well-defined block copolymer.