Sustainable Epoxy Vitrimers from Epoxidized Soybean Oil and Vanillin

Epoxidized soybean oil (ESO)-derived epoxy thermosets are usually limited by their poor mechanical properties and non-reprocessability. Herein, we report sustainable epoxy vitrimers synthesized facilely by curing ESO with vanillin-derived Schiff base (VSB) dynamic hardener with 1,2-dimethylimidazole as an accelerator. The phenolic hydroxyl of VSB showed high reactivity toward the epoxy group of ESO with a curing activation energy of 108.9 kJ·mol–1. The network rigidness and cross-link density of the epoxy vitrimers are adjustable by simply changing the feed ratio of flexible ESO and rigid VSB, which enables us to tailor the mechanical properties of the vitrimers easily over a wide range from soft to tough and hard. The dynamic Schiff base bonds provide the epoxy vitrimer with excellent reprocessability, weldability, reconfigurability, and programmability, which facilitates the recycling and processing of the cured epoxy materials. With tunable mechanical properties, reprocessability, and multifunctionality, the ESO-derived epoxy vitrimers are of great potential as alternatives to traditional epoxy thermosets.