The integrity of materials is a prerequisite for ensuring their performance. Any damage or defect may result in materials not meeting the requirements of application. For all kinds of materials, self-healing properties are strongly needed, especially for the hydrogels used as drug delivery carriers, tissue engineering scaffolds and functional device coatings because of their special application requirements. Developing self-healing hydrogels which can heal itself to maintain its initial performance after being damaged is vital to ensure the safety and reliability of materials in the use cycle, and thus has attracted more and more attentions. In general, self-healing hydrogels can be divided into two types based on the forces between polymer chains. The first kind is formed by dynamic covalent bonds, including disulfide bonds, Diels-Alder cycloaddition reaction, imine bond/Schiff base interaction, etc. Others are formed by physically crosslinking of non-valent bonds like hydrogen bonds or van der Waals' force, host-guest interaction, the interaction between polyelectrolyte, interaction of metal ligand, hydrophobic association, etc. Due to the stability of covalent bonds, most hydrogels formed by covalent bonds are stable and can exhibit good mechanical properties. Howe-ver, these hydrogels have many limitations, including poor response to external stimuli, inability to be remodeled after being manufactured, and unable to heal themselves after being damaged. Thus, the development of self-healing hydrogels based on dynamic covalent or physical crosslinking has become a trend. Self-healing hydrogel not only exhibit high swelling ratio and water content, biocompatibility and biodegradability, but also has the ability to repair the fault, which can be used for tissue engineering, wound dressing, drug release and biosensing fields, prolonging the lifespan of materials and showing excellent application potential. This review introduces the progress on the development of self-healing hydrogels based on dynamic reversible non-covalent system in recent years. The self-healing hydrogels are classified according to different healing mechanisms. The fabrication methods and application fields of self-healing hydrogels based on hydrogen bonding, reversible metal coordination, hydrophobic association and various interaction forces are reviewed respectively, and the problems and prospects of hydrogels based on dynamic reversible non-covalent system are discussed, aiming at providing ideas for the design, preparation and application of such hydrogels. © 2020, Materials Review Magazine. All right reserved.
