The photosensitive groups of photochemical self-healing polymers can undergo photochemical reactions under light irradiation,and promote diffusion,permeation and entanglement of macromolecular chains,followed by the rebonding of cracked surfaces via the newly formed chemical bonds.The technique has broad application prospects in the fields of smart coatings,optical materials and devices,soft photo-actuators,wearable flexible electronics,etc.As a clean energy,light stimulus is environmentally friendly,low-cost,and easily available,and has a high spatiotemporal resolution,which can achieve spatial and temporal control like remote activation and remending of localized damages.Starting from the types of photochemical reactions,including photo-reversible cycloaddition reactions,photo-induced isomerization reactions,dynamic reversible exchange reactions,and dynamic dissociation-association equilibrium reactions,the present article reviews the structural characteristics,healing principles and research progress of self-healing polymers containing various photosensitive chemical units.Based on the above analyses,the challenges and development trends in this emerging field are further analyzed.
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