Closed-loop chemically recyclable covalent adaptive networks derived from elementary sulfur.

The development of sulfur-rich polymers derived from elementary sulfur provides an innovative approach to industrial waste valorization. Despite significant advancements in polymerization techniques and promising applications beyond traditional polymers, polysulfide networks are still primarily stabilized by diene crosslinkers, forming robust C-S bonds that hinder the degradation of sulfur-based polymers. In this study, the anionic ring-opening copolymerization of chemically homologous S and cyclic disulfides was explored to yield robust sulfur-rich copolymers with high molecular weight. The incorporation of polysulfide segments not only efficiently activated the crosslinked networks for excellent reprocessability and mechanical adaptability but also endowed the resulting copolymer with high optical transparency in the near-infrared region. More importantly, the dynamic disulfide crosslinking sites promoted the chemical closed-loop recyclability of the polysulfide networks reversible S-S cleavage. This innovative inverse vulcanization strategy utilizing dynamic disulfide crosslinkers offers a promising pathway for the advanced applications and upcycling of high-performance sulfur-rich polymers.