Recent achievements in self-healing materials based on ionic liquids: a review

In recent years, self-healing materials have become popular for their repairable properties, which can stabilize the service performance and prolong lifetime. Ionic liquids, one of the most important self-healing agents, have attracted much attention because of their excellent conductive properties, high healing efficiency, and facile healing condition. In this review, the self-healing mechanism based on ionic liquids and the factors that affect their healing efficiency are explored. On the one hand, ionic liquids endow materials with self-healing character due to the presence of secondary bonds including hydrogen bonds, ion–dipole interactions, and ionic aggregation. One the other hand, ionic liquids are combined with other materials and impart self-healing properties due to reversible chemical reactions such as Diels–Alder, coordination, and electrochemical reaction. In addition, the effects on the self-healing function of ionic liquids are reviewed, including their ionic diffusion ability and environmental conditions. Last, challenges regarding self-healing materials concerning ionic liquids are presented.