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.
Raut et al. (Fri,) studied this question.