Synthesis of Ti3C2 MXene@PANI composites for excellent anticorrosion performance of waterborne epoxy coating

Ti3C2 MXene nanosheets have become a research hotspot in the anticorrosion field owing to their excellent barrier performance and mechanical properties. However, the utilization of different etching agents for the preparation of Ti3C2 MXene nanosheets has positive or negative influence on corrosion protection of waterborne epoxy coating (WEP) for metal owing to their quiet distinct electrical conductivity. In this study, we successfully synthesized multilayer Ti3C2 MXene nanosheets, and Ti3C2 [email protected] composites, such that PANI with high doping levels were uniformly anchored on the Ti3C2 MXene nanosheets' surface via in situ intercalation polymerization. Moreover, we verified the LiF and HCl treatment of Ti3C2 MXene accelerated the failure of WEP coating, which can be attributed to its higher electrical conductivity caused by the intercalation of Li+ than that of HF treatment. Ti3C2 [email protected] composites significantly improved the corrosion resistance of the WEP coating, thus greatly resolving the accelerating corrosion issue of Ti3C2 MXene. 0.3 wt% or more Ti3C2 [email protected]/WEP coatings' corrosion current density, impedance modulus, and charge transfer resistance increased by 1–2 orders of magnitude than that of pure WEP and Ti3C2 MXene/WEP in 3.5 wt% NaCl after 10 days of immersion. These results demonstrated that the synergistic effect of Ti3C2 MXene nanosheets' barrier effect and PANI's passivation effect enable Ti3C2 [email protected] composites with lower electrical conductivity to achieve long-term and efficient corrosion protection in WEP coating for Q235 steel.