Closed-Loop Recycling of Tough Epoxy Supramolecular Thermosets Constructed by Hyperbranched Topological Structure

Covalent adaptable networks are critical for the recycling and reuse of cross-linked epoxy thermosets. However, a major challenge is to develop efficient recyclable strategies while maintaining the high-performance of epoxy thermosets. Here, we synthesized vanillin-based hyperbranched epoxy resin (VanEHBP) to prepare tough epoxy supramolecular thermosets. The supramolecular structures were constructed with VanEHBP via intermolecular hydrogen bonds, intramolecular and intermolecular cavities, dual dynamic covalent bonds (imine exchange and transesterification). The epoxy thermosets exhibited excellent mechanical properties, as well as fast reprocessability, which can be reprocessed at 120°C within 30 sec and maintain about 100% of tensile strength. Importantly, the epoxy thermosets can be easily fully recycled under room temperature and the recovered materials can preserve 93.5% of mechanical properties of the original samples. This wok represents a unique strategy for developing room-temperature closed-loop recyclable epoxy thermosets with superior comprehensive performance and promising practical application prospects.