Multiple cross‐linked networks enhanced ENR‐based composite with excellent self‐healing properties

Self‐healing property is an excellent feature that can improve the reliability and durability of the materials. In this study, carboxylic multi‐walled carbon nanotubes (S‐CNTs) and 2,2′‐dithiodibenzoic acid (DTSA) were introduced into epoxidized natural rubber (ENR) to prepare a self‐healing rubber. S‐CNTs and DTSA could react with epoxy groups of ENR to effectively cross‐link ENR, in which the cross‐linked network consisted of reversible disulfide bonds, β‐hydroxyl ester bonds, and hydrogen bonds. The reconfigurable cross‐linked network endowed the ENR/S‐CNTs/DTSA composites with great self‐healing behavior with efficiency up to 99.7%. The multiple cross‐linked networks also enhanced the mechanical properties of the composite, whose tensile strength reached more than 400% of the neat ENR. Additionally, optical microscope and scanning electron microscopy disclosed the evolution of the damaged area during the self‐healing process, and the crack could be completely repaired after the healing process. This work provides an effective and concise method to prepare self‐healing ENR‐based elastomer, and it may expand the research scope of self‐healing materials.