Fully recyclable and tough thermoplastic elastomers from simple bio-sourced δ-valerolactones
Kai Ma, Haiyan An, Jiyun Nam, Liam T. Reilly, Yilin Zhang, Eugene Y.‐X. Chen, Tieqi Xu
Abstract
While a large number of chemically recyclable thermoplastics have been developed in recent years, technologically important thermoplastic elastomers (TPEs) that are not only bio-based and fully recyclable but also exhibit mechanical properties that can rival or even exceed those petroleum-based, non-recyclable polyolefin TPEs are critically lacking. The key challenge in developing chemically circular, bio-based, high-performance TPEs rests on the complexity of TPE’s block copolymer (BCP) structure involving block segments of different suitable monomers required to induce self-assembled morphologies responsible for performance as well as the control and monomer compatibility in their synthesis and the selectivity in their depolymerization. Here we demonstrate the utilization of bio-sourced δ-valerolactone (δVL) and its simple α-alkyl-substituted derivatives to produce all δVL-based polyester tri-BCP TPEs, which exhibit not only complete (closed-loop) chemical recyclability but also excellent toughness that is 2.5–3.8 times higher than commercial polyolefin-based TPEs. The visualized cylindrical morphology formed via crystallization-driven self-assembly in the new all δVL tri-BCP is postulated to contribute to the excellent TPE property. While a large number of chemically recyclable thermoplastics have been developed in recent years, technologically bio-based and fully recyclable thermoplastic elastomers (TPEs) with excellent mechanical properties are lacking. Here the authors demonstrate an all δvalerolactone-based polyester tri-BCP TPEs, which exhibit not only closed-loop chemical recyclability but also exceptional toughness.