Multi-functional epoxy vitrimers: Controllable dynamic properties, multiple-stimuli response, crack-healing and fracture-welding

Vitrimers, a new generation of polymeric materials, have been widely investigated to resolve the intersection of thermoplastics and thermosets, relying on the exchange reactions in networks. However, it is still a challenge to develop multi-functional vitrimer materials. Herein, multi-functional epoxy vitrimers that exhibited controllable dynamic properties, multiple-stimuli response, crack-healing and fracture-welding were prepared by introducing Fe3O4 nanoparticles into the networks of dual dynamic epoxy vitrimers. It was revealed that the typical dynamic parameters of vitrimer including the characteristic relaxation time (τ), activation energy (Ea), Arrhenius prefactor (τ0) and topology freezing transition temperature (Tv) could be readily adjusted in the multi-functional epoxy vitrimers. Moreover, the multi-functional epoxy vitrimers were simultaneously responsive to temperature, near infrared and magnetic field, while they could be driven by magnets, heated by near infrared and healed or welded by heating. Upon heating or near infrared, the cracks in samples could be successfully healed. Besides, by the cooperation of heating and magnet or near infrared and magnet, the multi-functional epoxy vitrimers were able to achieve non-touch welding of factures. These multi-functional epoxy vitrimers might have potential application in improving the reliability and extending the lifetime of polymeric materials. Meanwhile, the facile way to functionalize the epoxy vitrimers is estimated to be suitable for other vitrimer materials.