Performance-Guided Design of Chemically Recyclable Polymeric Materials: A Case Study on Thermoplastic Elastomers.

Thermoplastic polymer materials include both plastics and elastomers. Elastomers stand out as a crucial class of materials because of their wide-ranging applications. Polymers that can depolymerize back to their original monomers present a hopeful avenue to tackle the problems associated with polymer sustainability. In recent years, a great deal of research has been centered on the chemical recycling of monomers of polymers, and there are numerous reviews on this topic. Nevertheless, these reviews typically classify materials according to polymerization methods or polymer types, seldom taking into account the functional classification of the products. This method of categorization creates difficulties for those interested in material application scenarios, as they find it hard to obtain relevant information. Hence, this perspective takes a function-oriented approach, offering solutions for recyclable thermoplastic elastomers (TPEs) by classifying them into polyurethanes, copolyesters, and polyolefins with specific sequence control (e.g., homo, random, alternating, triblock, pseudotriblock, and multiblock). We offer an overview of the synthesis methods of various polymers and the properties of the constructed TPEs, making comparisons with those of conventional TPEs. Special attention is given to the depolymerization process, including the necessary conditions and recovery efficiency of the constituent monomers. Finally, we put forward future directions for the chemical recycling of TPEs, highlighting the critical issue of "monomer reuse and performance degradation over successive recycling cycles" that has been overlooked. This perspective seeks to promote more in-depth, cross-disciplinary research involving both academic and industrial partners to develop next-generation TPEs with improved sustainability.