(626e) Tribology of Confined Imidazolium-Based ILs Using Atomistically-Detailed Molecular Simulations

Modern industrial lubricants should possess high viscosity index, corrosion prevention, and thermal, hydraulic, and oxidative stability to reduce wear and friction. Although existing lubricants already fulfill most of these requirements, their current formulation still causes an average of 33% of fuel energy losses. Moreover, many conventional lubricants are a source of environmental concerns. Imidazolium-based ionic liquids (ILs) as friction modifiers have shown promising results to become great candidates for the matter. When utilized as an additive to conventional oils, it further decreases friction, wear, energy loss, and toxicity and requires only minor production alterations while overall oil consumption drops. In this work, we will use molecular dynamics simulations to study the tribological properties of pure imidazolium-based ILs with various architectures. The shear flow simulations in nanoconfinement will be induced in the systems by the relative motion of solid walls with respect to each other. The shear and normal stresses response will be determined at different rates. Using the shear and normal forces acting on the walls, the friction coefficient will be determined at different rates, and this parameter will be linked to the molecular structure of ILs and their adsorption behavior on the surface of the wall. In addition, to compare the simulation results with experiments, Hersey number, which quantifies the dependence of the friction coefficient between the surface and liquid on the viscosity and geometry of the surface, will be calculated in these simulations, and the results will be presented in the form of a universal curve, which can be used for designing ILs with a target tribological properties.