Friction control with nematic lubricants via external fields.

We study the connection between sliding friction and the phase behavior of a simple rigid bead-necklace model of a liquid crystal (LC) lubricant layer confined between two parallel plates. The dynamics is dependent on competing LC ordering mechanisms, including the direction of sliding, and an applied (electric) field. Together with temperature and an applied pressure, determining whether the lubricant is in a fluidlike isotropic state or in a layered in-plane nematic state, such ordering is found to control the frictional properties of the lubricant. Our extensive molecular dynamics simulations reveal in a detailed manner how friction can be controlled via applied fields. The results are expected to help in designing novel strategies to develop lubricants with dynamically controllable properties.