An ethyl cellulose-based supramolecular gel composite coating for metal corrosion protection and its self-healing property from electromagnetic heating effect

The barrier coating is the most important and effective method for corrosion protection. However, inevitable defects of various scales from micro to macro on coatings due to mechanical damage, aging, corrosive medium penetration, etc. will lead to coating failure. Usually, the damaged coating can only be removed and then recoated. At present, most of coatings are disposable coating and can not be recycled or healing repeatedly. In this paper, a supramolecular gel composite coating was prepared with ethyl cellulose, castor oil, mineral oil, and Fe3O4 nanoparticle, which are bonded together by hydrogen bonds and Van Der Waals forces. This coating could be multiple healed in situ by an alternating magnetic field based on the electromagnetic heating effect of Fe3O4 particles. The SEM/EDS results indicating that the best content of Fe3O4 in coating is 10% for good dispersion. Under an alternating magnetic field, the composite coating can be uniformly heated through hysteresis loss, and starts to heal when the temperature of the composite coating reaches 80 °C. After self-healing process, the mechanical properties and corrosion resistance of the composite coating have almost no difference with the original intact coating. Since the supramolecular gel is bonded by hydrogen bonding and Van Der Waals forces, these bonds are opened when heated and recombined after cooling without any change of properties. Therefore, the microstructure of supramolecular gel composite coating has no significant change and the corrosion protection performance has not decreased after 10 times of healing. •The supramolecular gel coating consists of the skeleton structure and the dispersed phase filled with oil.•The Fe3O4 nanoparticles in coating is beneficial to mechanical properties, and gives the self-healing ability to coating.•The coating keeps the same mechanical property and corrosion resistance after multiple times of in situ healing.