Ring-Opening Polymerization of Lactones to Prepare Closed-Loop Recyclable Polyesters

The large production and indiscriminate disposal of plastics have resulted in serious resource and global environmental crises, which has raised a demand to develop a more sustainable and circular plastics economy. An ideal strategy to address the end-of-life issue of plastics is to develop next-generation polymers with closed-loop life cycles, which can be selectively depolymerized back to monomers at the end of their service life. Aliphatic polyesters prepared by ring-opening polymerization (ROP) of moderately strained lactones have shown great potential in closed-loop recyclable polymers. This Perspective highlights the recent achievements for closed-loop recyclable polyesters that are derived from four-, five-, six-, and seven-membered lactones by focusing on the discussion of thermodynamic and kinetic considerations, monomer design principles and polymer preparations, material properties, and chemical recyclability. Finally, the current challenges and possible directions for closed-loop recyclable polymers are also discussed.