Ring-opening copolymerization of hydroxyproline-derived thiolactones and lipoic acid derivatives†

Ring-opening copolymerization is an important means to combine the properties of two or more monomers and fine-tune the properties of polymers. The copolymerization of two different types of monomers with full recyclability, however, has been rare. Here, we copolymerized the rigid 4-hydroxyproline-derived thiolactone with various lipoic acid derivatives that have flexible backbones to prepare poly(thioester-co-disulfide) copolymers with tunable thermal and mechanical properties. Owing to the full recyclability of both types of monomers, the resulting copolymers can be completely depolymerized to recycle both monomers in high monomer yields. This work provides a detailed understanding regarding the kinetics and controllability of the copolymerization system of thiolactone and 1,2-dithiolane, which may facilitate the design, modification, and strengthening of new recyclable polymer materials in the future.