Breaking the tribocorrosion threat: An active-passive PANI microcapsules@MXene network enabling on-demand healing and lubrication in epoxy coatings

Abstract

Although coating protection mechanisms are well understood for individual corrosion or wear conditions, tribocorrosion presents a unique challenge where synergistic interactions between mechanical friction and electrochemical corrosion accelerate coating degradation. Here, polyaniline microcapsules containing linseed oil, 2-mercaptobenzothiazole, and rhodamine B were in-situ loaded onto MXene nanosheets, and subsequently incorporated as multifunctional fillers into an epoxy coating. The tribocorrosion behaviors and the relevant mechanism of as-prepared coatings were evaluated via experiment characterization and molecular dynamics simulation. During the tribocorrosion process, the epoxy coating with pH/mechanical dual-responsive characteristics demonstrated the highest and most stable open-circuit potential (-0.44 V, ∆_OCP < 0.09 V). Its coefficient of friction was the lowest (0.16), and the wear rate (1.8 × 10^-6 mm³/N·m) was reduced by two orders of magnitude compared to pure epoxy coating (3.68 × 10^-4 mm³/N·m). The Raman characterization of worn surface at different durations revealed that the signals of MXene and linseed oil at the friction interface gradually increased as the process progresses. The lubricating film composed of MXene and linseed oil progressively evolved from an initially fragmented and discontinuous state into a compact and well-organized composite network as the tribocorrosion duration increased. Furthermore, the intelligent tribocorrosion system possessed a 105% self-healing efficiency with significant fluorescence quenching, ultimately realizing a remarkably low tribocorrosion synergy coefficient of only 1.18. The combination of experimental analysis and molecular dynamics simulations revealed that the excellent tribocorrosion resistance originated from an active-passive protection mechanism constructed by the microcapsules@MXene network. The formation of a linseed oil/MXene-based lubricating film reduced interfacial friction, while the strong interfacial bonding improved resistance to mechanical deformation. This work designed an intelligent anti-tribocorrosion coating, expanding the strategy for protecting equipment surfaces in harsh environments.