Photoinitiated thiol–epoxy addition for the preparation of photoinduced self-healing fatty coatings

Abstract

Herein, we report the use of the photoinitiated thiol–epoxy chemistry for the preparation of a new biosourced self-healing coating. Epoxidized cottonseed oil is used as the main reagent (>80 wt%) and photocrosslinked in the presence of 0.25 equivalents of 7-mercapto-4-methyl coumarin, used as a photodimerizable and healable reactant. The reaction is initiated with 2 wt% of a photobase generator (PBG). The stability of the thiol–epoxy mixture under storage and the oxygen-promoted photoinitiating system are some of the advantages illustrated in this study. The physicochemical properties of the resulting coatings as well as the photoreversibility of the coumarin derivative once grafted on the vegetable oil are studied. The photoinitiation step is demonstrated to be efficient for the grafting of the healing reagent as well as for epoxy homopolymerization.