Surface morphology and molecular conformation for ultrathin lubricant films with functional end groups

Using molecular simulation techniques based on a coarse-grained, bead-spring model, we examined the static and dynamic properties of linear perfluoropolyethers (PFPEs) in a nanoscale lubricant film on a solid wall. The conformation of the PFPEs, as predicted by the anisotropic radius of gyration, exhibits an oblate structure near the wall, but recovers a spherical shape as the distance from the wall increases. The density profile of the functional end groups for the PFPE molecules shows a characteristic oscillation as a function of the distance from the wall, indicating molecular layering. We also used the simulated surface morphology to examine the PFPE film roughness. Our preliminary dynamic simulations indicate that the wall interaction produces an anisotropy in the self-diffusion coefficient.