Confined Nanoparticle Solutions for Nanotribological Applications

Ramesh Chembeti and Jee-Ching Wang. Department of Chemical and Biological Engineering, Missouri University of Science and Technology, 400 W. 11th Street, Rolla, MO 65409-1230

Current advances in micro- and nano-electromechanical devices (MEMS and NEMS), micro and nanofluidic systems, and other nanotechnological areas all involve the tribological issues of friction, wear, and lubrication at the micro and nanoscale. In nanotribology, the lubricant films are molecularly thin and have been shown to possess properties that are significantly different from those of bulk fluids but not desirable for tribological applications. These properties cannot be explained by continuum fluid theories but have been shown by recent simulation studies to be caused by layered configurations of lubricant molecules in nanoscale confinement.

In the presented work we have performed atomistic and coarse-grained molecular dynamic simulations to evaluate the potential of confined nanoparticle solutions for nanotribological applications. The model system considered includes alkanethiol-capped gold nanoparticles and n-hexane as solvent. We have observed a disruption of layering tendency of the symmetric solvent molecules by the presence of nanoparticles that have a very different size. This disruption of the layering phenomenon is studied as functions of nanoparticle concentration and film thickness. The resultant less layered or non-layered thin lubricant films can be expected to provide smooth lubrication and important tribological advantages including reduced friction, wear, and costs.