Aliphatic C–H Insertion Strategies Enhancing Interactions among Waste Rubbers for Recycling

The recycling of waste rubber (WR) is beneficial to the sustainable development of rubber industries. However, interactions among WR are weak, limiting the recycling of WR. In this work, our group designed bis-diazo compounds to promote interactions among WR for recycling through aliphatic C–H insertion strategies. Specifically, upon hot pressing, bis-diazo compounds produce bis-carbenes which react with C–H on the surface of WR by C–H insertions, and then we obtain recycled WR materials. As a result, stress–strain curves show that the strength of recycled WR increases steadily with the increase of bis-diazo compound loading, which has reached the level of butadiene styrene rubbers. Moreover, the introduced disulfide bonds endow recycled WR with reprocessability. Stress–relaxation experiments at different temperatures show that recycled WR with disulfide bonds have unique vitrimer viscoelastic properties. The feasibility of bis-diazo compounds to enhance interactions among WR through C–H insertions opens opportunities to recycle and reinvent industrial WR.