Rapid and Controlled Polymerization of Bio‐sourced δ‐Caprolactone toward Fully Recyclable Polyesters and Thermoplastic Elastomers.

The development of chemically recyclable polymers presents the most appealing solution to address the plastics' end‐of‐use problem. Despite the recent advancements, it is highly desirable to develop chemically recyclable polymers from commercially available monomers to avoid the costly and time‐consuming commercialization. In this contribution, we achieve the controlled ring‐opening polymerization (ROP) of bio‐sourced δ‐caprolactone (δCL) using strong base/urea binary catalysts. The obtained PδCL is capable of chemical recycling to δCL in an almost quantitative yield by thermolysis. Sequential ROP of δCL and l‐lactide (l‐LA) affords well‐defined PLLA‐b‐PδCL‐b‐PLLA triblock copolymers, which behave as thermoplastic elastomers with excellent elastic recovery, tensile strength and ultimate elongation. The upcycling of PLLA‐b‐PδCL‐b‐PLLA to recover ethyl lactate and δCL with high yields is achieved by refluxing with ethanol and then distillation under reduced pressure. [ABSTRACT FROM AUTHOR]