Catalyst-Free and Sustainable Bio-Based Epoxy Vitrimer Prepared Based on Ester Exchange and Imine Bonding

Conventional epoxy anhydride curing systems typically require large amounts of catalyst to ensure a high ester exchange rate, and the resulting cured epoxy vitrimer has renewable and self-repairing properties, but is limited by the amount of catalyst loading. In this study, a diol (VT) containing imine bonds was synthesized from vanillin (VAN) and tyramine (TA) to catalyze the epoxy-anhydride curing process, and glycerol triglycidyl ether (GTE) was co-cured with VT and methylhexahydrophthalic anhydride (MHHPA), which constructed a bio-based regenerative and repairable epoxy vitrimer with dual dynamic covalent bonds (GMV), the free hydroxyl groups in the crosslinked network could rapidly promote the ester exchange rate. The thermal, mechanical, solvent resistance, self-repairing, renewable and shape memory properties of GMV were systematically investigated by adjusting the ratio of anhydride and hydroxyl groups. It exhibits a better thermal stability property T_d5% (281.27℃) and a shorter relaxation time τ (12.15 s) at 140 °C. In addition, the scratches of GMV could be almost completely healed at 120 °C for 60 min, and this test demonstrated that GMV has better self-healing and renewable tests. The present work promotes the epoxy vitrimer species and expands the esterification scheme performed without catalyst.