Polydopamine-modified Ti3C2Tx to enhance anticorrosion of waterborne zinc-rich epoxy coating

Ti3C2Tx MXene with high specific area, abundant terminal groups, and good mechanical property has exhibited great potential application in anti-corrosion coatings. However, its high conductivity is a two-edged sword and can either be inhibited or be utilized. Hence, it is speculated that Ti3C2Tx MXene can be used to enhance the protection ability of waterborne zinc-rich epoxy coating by utilizing its high conductivity and high specific area. Herein, Ti3C2Tx MXene nanosheets modified with polydopamine were successfully prepared according to scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. And then polydopamine-modified Ti3C2Tx was incorporated into waterborne zinc-rich epoxy coating to improve its anticorrosion performance. The polydopamine-modified Ti3C2Tx composites exhibit excellent dispersibility and compatibility with epoxy resin due to the enhanced intermolecular interactions between modified-Ti3C2Tx and epoxy resin, which was demonstrated by experiment and molecular dynamics simulation. After four weeks of immersion in 3.5 wt% NaCl solution, the |Z|0.01Hz value of composite coating (3.0 × 105 Ω cm2) was about three times larger than that of pure zinc-rich epoxy coating (1.1 × 105 Ω cm2). And the Rc value of composite coating was about one order of magnitude higher than that of pure zinc-rich epoxy coating. The better anticorrosion performance of composite coating was attributed to the polydopamine-modified Ti3C2Tx's dual functions of building electrical connection and exerting barrier effect. This work is beneficial to broaden the application of Ti3C2Tx MXene and enrich the protection theory of waterborne zinc-rich epoxy coating.