Self-healing hydrogels based on reversible noncovalent and dynamic covalent interactions: A short review

The self-healing capability of a material refers to its ability to autonomously heal fractures or defects and restore its original structures and functionalities. Self-healing hydrogels, with enhanced lifespan and mechanical performances compared to traditional fragile hydrogels, can serve as ideal synthetic analogues of living tissues, holding great promise in a wide range of biomedical, electrical and environmental applications. Reversible interactions play crucial roles in the construction of self-healing hydrogel networks. A deep understanding of these bonds is critical for the rational design of hydrogels with desirable properties. In this short review, we first introduce the experimental tools for the direct measurements of reversible intermolecular interactions, followed by discussing the self-healing hydrogels via diverse noncovalent interactions (i.e., hydrogen bonding, ionic interaction, metal-ligand coordination, hydrophobic association and π-interactions) and dynamic covalent bonds (i.e., imines, boronic esters, hydrazones and disulfide bond). Challenges and our opinions on future development of self-healing hydrogels are also provided.