Encapsulation of linseed oil in graphene oxide shells for preparation of self-healing composite coatings

Self-healing microcapsules were filled with a glue-like chemical that can repair damage and recover the original functions of materials. Graphene oxide (GO) was employed as the stabilizer of Pickering emulsions, and then the microcapsule shells were built upon the self-assembly of GO at oil/water interfaces. Linseed oil was encapsulated in the microcapsules as the healing agent. Several important factors were studied that affected the stabilization of the Pickering emulsions and the formation of the integral microcapsules, such as the pH value of GO aqueous solution, the GO/linseed oil mass ratio and the effect of surfactant. Chemical stitching of GO sheets by polyetheramine molecules were employed to enhance the chemical stability of the microcapsules. The waterborne polyurethane (PU) composite coatings containing 10 wt% microcapsules autonomously healed a scratch with 20 pm in width. After healing, the impedance modulus of the composite coatings was four orders of magnitude higher than neat PU.