Smart waterborne composite coating with passive/active protective performances using nanocontainers based on metal organic frameworks derived layered double hydroxides

Functional surfaces and coatings with excellent anticorrosion performances are of great significance for numerous engineering applications. However, developing waterborne coatings with long-term anticorrosion properties remains challenging. In this study, we developed a multifunctional nanocontainer for a waterborne coating matrix, using zeolitic imidazolate framework (ZIF)-derived layered double hydroxides (LDHs) as the gatekeepers for benzotriazole (BTA)-encapsulated mesoporous silica nanoparticles (MSNs-BTA). The LDHs outer layer and the ZIF intermediate layer endowed the MSNs-BTA@ZIF-LDHs nanocontainer with excellent compatibility, dispersion, and pH-responsive controllable release properties in the waterborne coating matrix. The waterborne epoxy composite coatings showed excellent passive and active anticorrosion performances, well-characterized by electrochemical impedance spectroscopy (EIS), permeation experiments, neutral salt spray (NSS) tests, and the scanning vibrating electrode technique (SVET). This excellent corrosion protection performance can be attributed to two factors: before corrosion, the MSNs-BTA@ZIF-LDHs served as passive nanofillers against corrosive media, significantly improving the barrier properties of the composite coatings; after the occurrence of corrosion, the MSNs-BTA@ZIF-LDHs acted as pH-responsive nanocontainers and released pre-loaded BTA corrosion inhibitors, preventing further damage to the exposed metal substrate. This study provides new insights into the development of multifunctional anticorrosion surfaces and coatings for various engineering applications.