Self-Healable, Recyclable, Adhesive Functional Elastomer Composites Based on Dual Dynamic Chemistries

Reversible cross-linking in elastomers has recently attracted significant attention as it may promote their recyclability and, more importantly, their self-healing capability, which extends material lifetime. Here, we demonstrate how the thermoreversible Alder–Ene (AE) click chemistry with bifunctional triazolinedione (bisTAD) can be integrated in a commercial poly(ethylene-co-vinyl acetate-co-glycidyl methacrylate) poly(EVG) elastomer. Epoxy-functional EVG was first grafted with indole-3-butyric acid (IBA), then rapidly cross-linked with bisTAD at room temperature under catalyst-free conditions. The cross-linked networks were reprocessable at 130 °C (via hot-pressing or solution-processing); variable temperature FTIR confirmed reversible bond cleavage/reformation during reprocessing. The AE networks exhibit recyclability (∼82–85% recovery), display self-healing behavior at 130 °C, and are thermally stable up to 300 °C (T5% > 300 °C). Moreover, adding cellulose nanofibers (CNF) allowed tuning of mechanical performance: addition of 3 wt % CNF was found to be optimal, and to yield the highest adhesion on several types of substrates (aluminum, wood, and glass) via synergistic AE exchange and hydrogen bonding.