A Strong, Tough, and Recyclable Styrene–Butadiene Rubber Achieved through Multiple Network Synergies of <i>N</i>-Acetyl-<scp>l</scp>-Cysteine

Styrene–butadiene rubber (SBR) is widely used in fields such as vehicles, wires, and medical instruments, but the inversible sulfur cross-link network of conventional SBR material hinders its reprocessability and recyclability. Although some efforts have been reported to fabricate recyclable SBR, developing effective strategies to realize both good recyclability and mechanical properties remains challenging. In this study, the biosourced multifunctional N-acetyl-l-cysteine (NALC) was exploited to fabricate strong, tough, and recyclable SBR materials using a multiple network synergies strategy. NALC is a cheap and commercially available amino acid with multiple functional groups, including sulfhydryl, amide, and carboxyl groups. The single modification of SBR with NALC can not only provide robust hydrogen bonding, endowing energy dissipation, and physical cross-linking capabilities, but also allows us to further improve the strength and toughness by the ionic cross-link of carboxyl groups with metal ions. Owing to the multiple network synergies of NALC, the as-prepared SBR reached a superior tensile strength of up to 13.5 MPa without sacrificing its good elasticity, which outperforms the traditional sulfur-vulcanized rubbers. Meanwhile, the resultant rubber can be readily recycled due to the reversible nature of the hydrogen bonds and ionic bonds. This work provides a promising route to high-performance recyclable SBR, facilitating the pursuit of sustainable rubber materials.