Controllable group tailoring enables enhanced pH-responsive behaviors of polydopamine delivery system in smart self-healing anticorrosion coatings

Nanomaterials as delivery systems loaded with corrosion inhibitors is a promising strategy for achieving self -healing anticorrosion coatings. However, the uncontrollable passive release of inhibitors brings challenges for scalable anticorrosion applications in different environments with wide-range pH values. Here, we propose an effective strategy for regulating the pH-responsive behaviors of polydopamine (PDA) delivery system by controllable group tailoring to enhance the corrosion inhibition effects in different environments. The delivery system (BTA@PDA) consisting of PDA and benzotriazole (BTA) were prepared by a convenient one-pot method. Based on the pH-dependent changes in charge of amine groups and hydroxyl groups, BTA@PDA showed the enhanced corrosion inhibition effects in acid or alkaline environments. Electrochemical impedance spectroscopy and energy dispersive spectroscopy were performed to characterize the self-healing behavior of scratched coatings added with BTA@PDA. The scratched coatings exhibited an increased impedance modulus due to the dual corrosion inhibition effects of BTA and PDA, triggered by the corrosion-induced pH variation. Moreover, the impedance modulus of the coating maintained at 2.03 x 109 omega cm2 after 21 days of immersion (only 1.06 x 108 omega cm2 for an epoxy coating). This study has a great significance for the design of pH-responsive smart coatings for scalable applications in different environments.