Cu-BTA complexes coated layered double hydroxide for controlled release of corrosion inhibitors in dual self-healing waterborne epoxy coatings

Abstract

Smart self-healing coatings with the active healing ability are the current research hotspot in the field of metal corrosion protection. In this work, we designed a novel corrosion protection system of waterborne epoxy. Under alkaline condition, Cu-BTA complexes were deposited on the surface of MoO42− intercalated Mg-Al Layered double hydroxide (MIH) by electrostatic assembly as pH-sensitive gatekeepers. When MIH@Cu-BTA(MIHC) nanosheets were filled into the coatings, the layered structures of Layered double hydroxide(LDH) improved the barrier properties of the coatings to prevent corrosive ions penetration. Meanwhile, the excellent ion exchanges ability of LDH could be used to reduce the concentration of Cl- ions, both of MoO42− ions and BTA could release quickly from MIHC in an acidic environment to achieve the self-healing effect. All of them cooperated to synergistically improve the anti-corrosion performance of the coating. The long-term protective performances and self-healing properties of WECs which loaded nano-containers were evaluated by salt spray test and electrochemical experiment. The impedance results indicate that the addition of MIHC(0.5 wt.%) increases the impedance of pure epoxy coating from 1.579 × 108 to 1.041 × 109 Ω cm2.