Semi-Empirical Molecular Modeling of Ionic Liquid Tribology: Ionic Liquid-Hydroxylated Silicon Surface Interactions

The interactions between selected ionic liquids and modified silicon surfaces are modeled in this article using semi-empirical methods. The modeled ionic liquids include a series of ionic liquids consisting of imidazolium derivatives with Cl- as the anion interacting with hydroxylated silicon wafers. A second series consists of symmetrical and asymmetrical dicationic imidazolium derivatives with PF6 (-) or BF4 (-) as the anion interacting with hydroxylated single crystal silicon wafers. The tribological properties of these ionic liquids and their interactions with silicon surfaces are modeled using a rolling hydroxylated silicon surface. The ionic liquids are allowed to form a complex with this surface, and the enthalpies of complex formation are seen to correlate with the tribological properties of the ionic liquids.