Hydrogels

a kind of smart soft material that consists of water and distinctive 3D cross-linked network structures

have been widely used in many fields

such as drug delivery

cartilage repair

waste treatment and electronic equipment. However

the applications of hydrogels are often limited by their poor mechanical properties and self-repairing capability. Currently

the reported tough hydrogels are usually not or only weakly self-repairing

and self-healing hydrogels are usually very weak in mechanical properties. Developing hydrogel materials with both high mechanical strength and selfhealing properties is significant from both academic and industrial points of view. The present paper summarizes the development of tough self-healing hydrogels covering from preparation methods

network structures

to properties. It provides an outlook of the perspective of tough self-healing hydrogels.