Recyclable and heat-healable epoxidized natural rubber/bentonite composites

Conventional crosslinking endows rubbers with excellent mechanical properties, at the same time, turn them to be thermosets with the impossibility of recycling and self-healing. From the perspective of sustainable development of material, it is crucial and meaningful to integrate these charming properties into crosslinked commercial rubbers. In this paper, we prepared a recyclable and healable epoxidized natural rubber (ENR)/citric acid-modified bentonite (CABt) composite. CABt with numerous carboxyls on surface served as cross-linker to covalently crosslink ENR through exchangeable beta-hydroxyl ester linkages, as well as efficient reinforcer for ENR. Because of the transesterification reactions of beta-hydroxyl ester linkages between CABt and ENR, ENR/CABt composites could alter the network topology at elevated temperature. Meanwhile, the low crosslink degree of network and inherent stickiness of ENR matrix facilitated chain diffusion and transesterification reactions of beta-hydroxyl ester linkages, which made ENR/CABt composites recycled and healed. Thus, we envision that our work would open up new avenues to design more crosslinked rubber composites showing recyclable, healable and adaptable abilities.