Rapid self-healing and recycling of multiple-responsive mechanically enhanced epoxy resin/graphene nanocomposites

The development of self-healing and recyclable crosslinked polymeric materials has drawn considerable attention in recent years. However, the bulk healing or remending speed is usually slow due to the high viscosity of high M-w polymers, and the low rate of thermal conduction from material surfaces into the central matrix. Herein, a rapid self-healing and recyclable high-performance crosslinked epoxy resin (ER)/graphene nanocomposite is reported by simultaneously incorporating thermally reversible Diels-Alder (DA) covalent bonds and multiple-responsive graphene into the ER matrix. Therefore, graphene in proximity to the DA crosslinkages can instantly trigger the retro-DA reactions by converting the absorbed energies (e.g. infrared light, microwave, etc.) into heat, and thus enables rapid self-healing and recycling. Furthermore, the well-dispersed graphene (<1 wt%) could significantly enhance the mechanical strength of the ER. In situ variable temperature solid-state NMR spectroscopy was used to monitor the reversible DA reactions at the molecular level, and the high healing and recycling efficiency of ER/graphene nanocomposites was well demonstrated by multiple approaches.