"In this study, solutions of alkanethiol-capped nanoparticles in alkane are examined using molecular dynamics simulations for their nanotribological potential based on the hypothesis that fluid molecules of very different sizes may interrupt each other's layering tendency to result in less layered or non-layered configurations and provide better lubrication for nanodevices. An effective nanoparticle-nanoparticle pair potential based on previous atomistic approach is used and the temperature and parallel pressure are controlled in place of chemical potential for defining thermodynamic state. When compressed, the confined nanoparticle-containing alkane films generate reduced oscillations in perpendicular forces and smoother expansion in lateral dimensions, indicating lesser extent of layering due to the presence of much bigger nanoparticles. The nanoparticles are found to be well dispersed by the alkane solvent throughout all separations, meaning no or little tendency to form clusters or aggregate towards the confining surfaces, which is important for the stability and quality of the nanoparticle solutions as nanotribological lubricant. When sheared by a sliding surface, the confined fluids tend to move in the same parallel direction so that their density profiles remain practically unchanged. The shear stress resulting from the sliding surface has been calculated and found to increase with faster sliding speed but not proportionally. More importantly, the presence of the nanoparticles in the lubricant films reduces the shear stress noticeably and thereby reducing the apparent viscosity and frictional force. This effect is particularly evident under relatively large sliding speed and large surface separations. Regarding mobility, the nanoparticles exhibit lower diffusivity in nanoconfinement than typical fluids and their diffusivity can be enhanced by shearing"--Abstract, page iv.
Wang, Jee C.
Neogi, P. (Partho), 1951-
Ge, Yu-Ning (Louis)
Chemical and Biochemical Engineering
M.S. in Chemical Engineering
National Science Foundation (U.S.)
University of Missouri Research Board
Missouri University of Science and Technology
viii, 72 pages
© 2008 Ramesh Chembeti, All rights reserved.
Thesis - Open Access
Molecular dynamics -- Computer simulation
Nanoparticles -- Analysis
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Link to Catalog Record
Chembeti, Ramesh, "A coarse-grain molecular dynamics study of the nanotribological properties of nanoparticle solutions" (2008). Masters Theses. 4629.