Malleable and self-healing rubbers covalently crosslinked by reversible boronic ester bonds

Covalent cross-linking of rubbers is essential to obtain high elasticity, which plays a significant role in practical applications. Integrating dynamic covalent bonds into rubbers is a reliable way to endow them with self-healing capacity to repair damage and extend their service life. Herein, we propose a facile and effective method to introduce a crosslinking network composed of dynamic boronic ester bonds into epoxidized natural rubber (ENR). The reaction between dopamine-modified ENR and the hydrolysate of boric acid in weak alkaline solution formed a cross-linking network with reversible boronic ester bonds. Owing to the rearrangement of the crosslinked network initiated by the boronic ester exchange reaction, covalently crosslinked rubbers exhibit relatively better malleability and excellent self-healing ability under moderate conditions (60 °C/24 h).