Recyclable and self-healing rubber composites based on thermorevesible dynamic covalent bonding

Commercial ethylene propylene diene monomer (EPDM) rubber grafted with maleic anhydride (EPDM-g-MA) was thermoreversibly crosslinked by silane modified silica. EPDM-g-MA was first modified with furfurylamine to obtain furan functionalized EPDM (EPDM-g-FA) which was then crosslinked with 3-methacryloxypropyl-trimethoxysilane (as electron-poor agent) modified silica via a Diels-Alder reaction. The as-formed rubber network could be broken at high temperature and reconstructed by thermal annealing, which were proven by differential scanning calorimetric analysis and solubility testing. The mechanical strength of the resulting EPDM/silica composites could be tailored by the amount of modified silica and were superior to the previously reported EPDM rubber crosslinked by low molecular organic agents. More importantly, the rubber composites showed good thermal reprocessability and self-healing behavior, by which the crosslinked composites could be recycled to use with comparable mechanical property as the original composites.