Hierarchical BP/MMT/AMT Nanohybrids for Multifunctional Waterborne Epoxy Coatings: Synergistic Enhancement of Corrosion Resistance, Tribological Durability, and Flame Retardancy

Simultaneous improvement of the tribological, flame-retardant, and anticorrosion properties of waterborne epoxy (WEP) coatings is highly desirable yet challenging. Herein, we report the rational design of multifunctional 2D nanoadditives (MBAs) by assembling a montmorillonite (MMT)/black phosphorus (BP) binary heterostructure with a corrosion inhibitor, 2-amino-5-mercapto-1,3,4-thiadiazole (AMT). Extensive structural characterizations confirm the successful integration of the MBA nanosheets. By embedding these nanosheets into a WEP matrix, the resultant composite coating (containing 0.4 wt % MBA, denoted as 4-MBA WEPC) delivers dramatically enhanced comprehensive performance. Remarkably, the wear rate is reduced by 93.62% relative to the pure WEP coating (WEPC), driven by an intersheet sliding mechanism that mitigates shear stress. Additionally, the dense carbon layer formed during the combustion process of 4-MBA WEPC indicates that it possesses outstanding flame-retardant properties. Crucially, 4-MBA WEPC exhibits exceptional long-term corrosion resistance, maintaining a low-frequency impedance (| Z 0.01 Hz |) nearly 3 orders of magnitude higher than that of the pure WEPC after 70 days of immersion in a corrosive medium. This remarkable durability originates from the synergistic combination of the robust physical barrier of the MMT/BP nanosheets and the active inhibition capabilities of AMT, presenting a promising paradigm for multifunctional protective coatings.