Development of a Multistimulus Response Silicon-Bridged/Fe₃O₄ Epoxy Vitrimer: Controllable Welding, Crack Healing, and Shape Memory

The emergence of vitrimer materials containing dynamic bonds provides a solution to the dilemma that traditional epoxy resins are difficult to recycle and reuse. However, the development of vitrimer materials with multiple functions, especially simultaneous multistimulus response properties, is still challenging. In this work, Fe 3 O 4 nanoparticle was introduced into epoxy vitrimer (ETOD-SA), containing Si–O segments and dynamic reversible ester bonds, to prepare a multistimulus response silicon-bridged/Fe 3 O 4 epoxy vitrimer (ETOD-SA-Fe 3 O 4 ) with controllable welding, crack-healing, and shape memory properties. The optimized ETOD-SA-Fe 3 O 4 exhibited superior flame retardancy (char residue was increased by 194.5%, while pHRR decreased by 31.8%), self-healing ability (8 min for a 48 μm scratch), shape memory, and mechanical properties. More surprisingly, ETOD-SA-Fe 3 O 4 was simultaneously responsive to magnetic field, near-infrared, and temperature, allowing crack healing of samples as well as controllable noncontact welding through the combination of near-infrared and magnet or heating and magnet. Therefore, these excellent properties could improve the durability and extend the service life of the epoxy vitrimer material, which will further expand its applications.