A pH-responsive hydrophilic controlled release system based on ZIF-8 for self-healing anticorrosion application

Abstract Giving the coating to exert a powerful active protective effect for metal substrates, such as self-healing property by encapsulating corrosion inhibitor into a pH-responsive release tool, is a crucial way to develop an efficient anticorrosive coating. Here, a pH-responsive hydrophilic controlled release system (BTA@ZIF-8@tannic acid, abbreviated ZBT) based on ZIF-8 for waterborne EP self-healing anticorrosive coating was reported. Encapsulation of BTA into ZIF-8 by a facile one-pot method and the resulting product showed a high loading percentage. The anticorrosion performance of composite coatings was studied by EIS, and the results indicated that ZBT could effectively enhance the protective performance of the coating and endow it with outstanding self-healing performance, in which the |Z|0.01 Hz was about 2 orders of magnitude higher than that of pure EP coating after 20 days of immersion. The outstanding performance is related to the excellent compatibility of ZBT, the blocking effect of newly produced hydrophobic substances and the corrosion inhibitor and ferric tannate protective films formed on the exposed metal surface. In this work, tannic acid plays a role of killing two birds with one stone in enhancing the corrosion protection performance of the coating. This synergistic strategy opens a new possibility to fabricating excellent anticorrosive coatings with efficient self-healing functionality.