Molecular Dynamics Simulations of the Interaction Between Graphene and Lubricating Oil Molecules

The microscopic interaction between graphene and liquid lubricating oil molecules significantly affects the rheological and tribological properties of the solid–liquid lubricating system. In this study, the interaction between graphene and six kinds of alkane oil droplets with different chain lengths was investigated by molecular dynamics simulations. Interaction energy, atomic concentration distribution, mean square distribution, curvature, centroid, and inclination angle were used to quantitatively describe the effect of interaction differences on lubricating performance. The results demonstrated that with the increase of the carbon chain length, the alkane molecules transformed from a spherical oil droplet model to an ordered layered structure. At the same time, the interaction energy and the angle with the Z coordinate axis were further increased. The self-diffusion movement and the degree of molecular bending were reduced during the interaction, indicating that long-chain alkane molecules interact strongly with graphene, and a dense multilayer adsorption film was formed by horizontal adsorption on the surface of graphene, thus exerting a good lubricating effect. In addition, it was found that the increase in temperature was beneficial to the occurrence of the adsorption process, but high temperature is not conducive to the stable adsorption of alkane molecules on the surface of graphene.