From Polymers to Rings and Back Again: Chemical Recycling of Polyesters to Macrolactones

Cyclic anhydride and epoxide ring‐opening copolymerization is a versatile and controlled route to make polyesters, gaining attention in different application sectors but so far the chemical recycling of these polyesters to cyclic monomers is under‐explored. Here, the catalytic chemical recycling of aliphatic polyesters to selectively form 16‐ and 18‐membered lactones is presented. The recycling reactions are catalysed using commercial tin octoate and conducted in the polymer melt (230 °C) resulting in high conversions to the macro‐lactones (>90%). The recycled macro‐lactones undergo catalysed ring‐opening polymerizations to produce polyesters with equivalent properties to the virgin materials.