Two-dimensional lamellar MXene nanosheets/waterborne epoxy composite coating: Dopamine triggered surface modification and long-term anticorrosion performance

The two-dimensional lamellar MXene nanosheets have exhibited remarkable potential in enhancing the corrosion resistance of waterborne epoxy (WEP) coating because of their excellent mechanical strength and physical barrier effect. However, the inherent instability of MXene in aqueous environments posed a significant challenge due to its susceptibility to oxidation and decomposition. Moreover, the excellent electrical conductivity of MXene can trigger galvanic corrosion, accelerating the rate of corrosion in coatings. To overcome these limitations, a facial surface functionalization of MXene nanosheets via one-step dopamine-triggered crosslinking with polyethyleneimine was developed, which was applied to reinforce the waterborne epoxy coating by a simple spraying technique. The efficient dispersion of functional filler, enhanced physical barrier, and interface compatibility contributed to the exceptional anticorrosion ability of WEP coating. Uniquely, the impedance of the 0.5 wt% modified MXene/WEP composite coating remained at 2.72 × 108 Ω·cm2 (at 0.01 Hz) after immersion in 3.5 wt% NaCl for 30 days, even with the coating thickness of around 55 ± 5 µm. This value was two orders of magnitude higher than neat WEP coating. Therefore, this work expanded the use of two-dimensional lamellar MXene nanosheets as functional fillers for realizing the long-term anti-corrosion ability of the waterborne epoxy coating.