Robust Epoxy Vitrimer with Simultaneous Ultrahigh Impact Property, Fire Safety, and Multipath Recyclability via Rigid-Flexible Imine Networks

Vitrimers have promise as adaptable materials capable of self-healing, shape reconfigurability, and remoldability due to dynamic covalent reactions occurring above their transition temperatures; however, their relatively poor mechanical properties, particularly compared to commercially available thermosets, have limited their further application in diverse industries. Herein, we demonstrate a rigid-flexible integrated strategy for fabricating robust epoxy vitrimers (EVs) with superb mechanical properties comparable to those of conventional epoxy thermosets. The rigid aromatic Schiff base moiety and flexible siloxane spacer increased the network rigidity and molecular weight between cross-links, endowing the EVs with high strength, ultratoughness, and rapid dynamic exchange of imine bonds. The EV displayed a rarely reported ultrahigh impact strength of 61.8 kJ·m–2 and realized the recyclability of the thermosetting resin through physical reprocessing and chemical recycling. Furthermore, it broke through the restriction on the plasticity of a robust EV network greatly limited by permanent cross-links, provided a solution to the inherent contradictions between high mechanical properties and facile malleability, and repaired the deficiency of brittleness and flammability toward conventional epoxy resins without any use of conventional flame-retardant elements, such as halogens and phosphorus. EVs based on this rigid-flexible integrated strategy enormously broaden the field of their application, and it is of great significance for the recycling of damaged, aged, or discarded epoxy resin-based materials as well as resource conservation and environmental protection.