Molecular dynamics study of the corrosion protection improvement of superhydrophobic dodecyltrimethoxysilane film on mild steel.

ABSTRACT

Recently, superhydrophobic surfaces have received increasing interest in metal corrosion protection due to their excellent waterproofing characteristics. However, little attention has been paid to the related anti-corrosion mechanism at the molecular level. In this work, the protection behaviors provided by the superhydrophobic dodecyltrimethoxysilane for mild steel were first explored using molecular dynamics (MD) simulation in terms of silane absorption orientations and water cluster wetting behaviors. The results show that the conformations of dodecyltrihydroxysilane (DTHS) on the Fe substrate are greatly dependent on the solvent environment. Typically, the DTHS molecule adopts a "standing" orientation with the hydrophilic head attached to the Fe surface and the hydrophobic tail remaining in the polar phase, which is conducting to generate a good repulsive effect on the water droplet. Based on this, the diffusion performance of corrosive species in the superhydrophobic DTHS film was further investigated. The computational results indicate that the corrosive species are confined to specific regions of the film, which results in a decreased diffusion coefficient. Additionally, the weak movement of DTHS molecules also increases the transport resistance of the corrosive medium through the superhydrophobic DTHS film, thereby improving the corrosion protection of the underlying metal substrate. The results obtained in this work will deepen our understanding of the anticorrosion mechanism of superhydrophobic silane films.