Self-Healing Coating with a Controllable Release of Corrosion Inhibitors by Using Multifunctional Zinc Oxide Quantum Dots as Valves

As an intelligent response system, self-healing anticorrosion materials containing nanocontainers have aroused increasing demands. It is highly expected that the nanocontainers can rapidly respond on corrosion signals to efficiently release corrosion inhibitors, meanwhile to avoid an undesirable leakage before the local corrosion happening. Herein, zinc oxide quantum dot (ZnO-QD)-sealed hollow mesoporous TiO2 nanocontainers loading with 14.2% benzotriazole (BTA) inhibitor have been successfully prepared [hollow mesoporous titanium dioxide nanospheres (HMTNs)–BTA@ZnO-QDs]. ZnO-QDs play the multifunctional roles on anticorrosion of the self-healing coating. The corrosion tests of coatings on the carbon steel well demonstrate that ZnO-QDs can not only act as a valve to seal and release BTA on the time but also act as a precursor to produce the protective film of Zn(OH)2 by the reaction of Zn2+ ions with OH– around the cathode region to inhibit the corrosion of carbon steel. After being soaked in 3.5% NaCl solution for 30 days, the |Z|0.01 Hz value of the coating with HMTNs–BTA@ZnO-QDs still maintains at 2.87 × 107 Ω cm2. Once the defects are formed in the coating, the acid-responsive ZnO-QD valves are rapidly decomposed to release BTA inhibitor; meanwhile, the resulted Zn(OH)2 layer prevent the carbon steel substrate from corrosion in the cathode area. Therefore, it could be promising that the present design of the nanocontainers matching with the multifunctional ZnO-QDs can offer a valuable strategy to construct the self-healing and anticorrosion coatings with a multiresponse to the corrosion environment.