A Biobased Self-Healing Thermoset Coating with a Dynamic Photosensitive Molecule

Abstract A biobased photo-healable thermoset coating has been developed from 4 components in only 2 steps via a solvent-free process involving an epoxy/amine reaction. Its composition includes epoxidized linseed oil and a dynamic molecule (4,4’-diaminodiphenyl disulfide) which, under UV irradiation, can be photolyzed reversibly. Compared to an analogous material without disulfide bond, this coating exhibits a lower crosslinking density and a higher elongation at break. Importantly, a 100 μm depth scratch has been significantly repaired under UV light: a photo-healable coating having both thermoplastic and thermosetting properties has thus been elaborated.