Inspired by biological system which can heal its wound

the self-healing material that can detect the damage and heal itself automatically has developed. Because of simple preparation process

widely application field and extensive healing types

the microcapsule-based system has attracted most research attentions. Its repair process is triggered by rupture of microcapsule when a crack propagates through the matrix

followed by release healing agent into the crack plane. Then the healing agent mixes with catalyst

bonds the crack through polymerization. The healing chemistry that can transform from low viscosity liquid into tough and hard thermoset is the key to facilitate healing process. This review summarizes the different chemistries used in state-of-the-art self-healing materials based on microcapsule

and mainly describes ring-opening metathesis polymerization of cyclic olefin

ring-opening polymerization reaction of epoxide

further curing reaction based on solvent and click chemistry. Moreover

the click chemistry becomes a particularly powerful method to design self-healing material because of its simple and efficient feature

including azide-alkyne reaction

Diels-Alder reaction

thiol-ene reaction and thiol-isocyanate reaction. The mechanism of self-healing chemistries and influence factors of self-healing efficiency are analyzed

and the limitations and benefits of the healing chemistry are discussed. Finally the challenges and future opportunities are highlighted.