Tough and Closed‐Loop Recyclable Thermoplastic Elastomers From Sequential Ring‐Opening Copolymerization of Bio‐Renewable β‐Methyl‐δ‐Valerolactone and δ‐Valerolactone

Abstract Despite the great successes achieved for the closed‐loop recyclable polymers in the last decade, thermoplastic elastomers (TPEs) with closed‐loop recyclability and good mechanical performances are largely underexplored. In this contribution, the preparation of PδVL‐ b ‐PβMVL‐ b ‐PδVL triblock copolymers via one‐pot sequential ring‐opening copolymerization of bio‐renewable β‐methyl‐δ‐valerolactone (βMVL) and δ‐valerolactone (δVL) is achieved. The obtained triblock copolymers behave as TPEs that exhibit superior tensile strength and toughness as well as comparable elasticity to the most previously reported polyester‐based and commercial styrenic copolymer‐based TPEs. Remarkably, these triblock copolymers can be depolymerized to recover pristine monomers with a high yield by simply heating the materials under reduced pressure in the presence of stannous octoate as the catalyst. The recovered monomers can be separated or directly used to prepare TPEs with comparable performances to original TPEs, thus establishing a closed‐loop life cycle.