Design of epoxidized natural rubber/poly(lipoic acid) elastomer with fast and efficient self-healing under a mild temperature

Most of the dynamic covalent bonds (DCBs) for self-healing rubber must be activated at relatively high tem-peratures due to the requirement of high energy during the exchange of dynamic bonds, which may lead to unexpected degradation or excessive crosslinking of rubber. Herein, we designed and fabricated a highly stretchable, self-healable and reprocessable rubber by introducing dynamic disulfide bonds into the crosslink network of epoxidized natural rubber (ENR). Lipoic acid (LA) was firstly uniformly dispersed into ENR via a latex film formation technique, and then underwent a dynamic covalent ring-opening self-polymerization during hot pressing process, during which the carboxyl group of poly(LA) attacked the epoxy group of ENR to form beta-hy-droxyl ester bond crosslinks. As a result, a revisable covalently crosslinked network without rigid steric hin-drance groups was constructed, which exhibited a super self-healing efficiency of 99 % after self-healing at 80 degrees C for only 3 h. The elongation at break of the elastomer could reach 1115 % and the recovery rate of reprocessing was as high as 91 %.

Automated summary

In this study, a highly stretchable, self-healable, and reprocessable rubber was successfully designed and fabricated by introducing dynamic disulfide bonds into the crosslink network of epoxidized natural rubber. The rubber demonstrated a super self-healing efficiency and high elasticity.