Accelerated self-healing performance of magnetic gradient coating

In this study, we present the novel self-healing magnetic microcapsule preparation of poly(urea-formaldehyde) embedded with benzotriazole (BTA) and magnetic multi-wall carbon nanotubes (MWCNTs) to accelerate the self-healing efficiency of the coating significantly. The BTA played a role of the corrosion inhibitor, while the magnetic MWCNTs served as a target for the formation process of self-healing magnetic gradient (SMG) coating. The magnetic microcapsules could be easily as well as rapidly migrated in the coating solution via an external magnetic field. The SMG coating not only shortened the migration route of the released BTA, but also accelerated quickly the formation of a passivation film, and the corrosion of the copper was hindered, after the coating was damaged mechanically. It was further demonstrated that initial self-healing efficiency of SMG coating was approximately 6.4 times more than that of self-healing coating without magnetism. The present work successfully demonstrated the accelerated self-healing activity of magnetic MWCNTs microcapsules in protecting copper surfaces. The outcomes might help to magnetize the material and guide future design of self-healing coating.