A Substitution-Desymmetrization of Recyclable Poly(β-Thioesters) Strategy for Crystallinity Regulation and High-Performance Adhesives

Structural regularity in polymers is a double-edged sword, enhancing crystallinity and thermal stability but often reducing processability and toughness. Here, we present a substitution-desymmetrization strategy to address this trade-off in chemically recyclable polythioesters (PTEs). Copolymerizing symmetric β-gem-dimethyl thiolactone with an asymmetric β-methyl-β-ethyl analog via rare-earth metal-catalyzed ring-opening polymerization enables precise backbone symmetry control, yielding tunable melting temperatures (90-170 °C) and ductility. The optimized copolymer self-assembles into hierarchical helical nanofiber bundles, achieving strong adhesion across substrates (lap-shear strength up to 9.48 MPa on iron). The adhesive performs well at extreme temperatures (-196 and 120 °C) and shows superior water resistance compared to commercial cyanoacrylate. Moreover, PTEs remain fully chemically recyclable. This work offers a sustainable platform for high-performance materials via symmetry engineering.