Self-Healing Epoxy Coatings via Focused Sunlight Based on Photothermal Effect

Epoxy coatings which can be healed via photothermal effect from focused sunlight are reported. The diamine of m-xylylenediamine (MXDA) and monoamine of 4-(heptadecafluorooctyl)aniline (HFOA) are reacted into the diglycidylether of bisphenol A (DGEBA) network. Via gradual replacement of MXDA with HFOA, the glass transition temperature and crosslinking density of the epoxy network are tuned to achieve the thermally induced healing based on chain diffusion and reentanglement. Aniline black (AB) with well absorptivity for sunlight is used subsequently as the organic photothermal compound, transferring the thermally induced healing into a sunlight responsive one. A common handheld magnifier, which can focus natural sunlight to the required power density (0.6–0.9 W cm⁻¹), is used to successfully heal one cracked coating in outdoor circumstance. This study provides a potential approach to achieve the convenient, precise, and timely healing for outdoor epoxy coatings. (Figure presented.).