Mechanically Robust, Self-Healable, and Reprocessable Elastomers Enabled by Dynamic Dual Cross-Links

Covalent cross-linking of rubbers is essential for obtaining high resilience and environmental resistance but prevents healing and recycling. Integrating dynamic covalent bonds into cross-linked rubbers can resolve the trade-off between permanent cross-linking and plasticity. The state-of-the-art elastomer-based dynamic covalent networks require either intricate molecular makeup or present poor mechanical properties. In this work, we demonstrate a simple way to prepare mechanically robust yet healable and recyclable elastomeric vitrimers by engineering dynamic dual cross-links of boronic esters and coordination bonds into a commercial rubber. Specifically, epoxidized natural rubber is covalently cross-linked with a boronic ester cross-linker carrying dithiol through chemical reaction between epoxy and thiol groups. The covalently cross-linked networks are able to alter the topologies through boronic ester transesterifications, thereby conferring them with healing ability and reprocessability. In particula...