Wetting and Hydrophobicity of Nanoscale Systems with Impurities
P. Gonnet, U. Zimmerli, J.H. Walther, T. Werder and P. Koumoutsakos
ETH Zurich, CH
Keywords: wetting, hydrophobicity, graphite, water, molecular dynamics, ions, impurities
Molecular dynamics simulations are performed to study the influence of surface and fluid impurities on water-carbon interfaces. In order to quantify these interactions we consider both the canonical problem of wetting of a doped flat graphitic surface by a water droplet with impurities and the influcence of static dipole moments perpendicular to the wall of a carbon nanotube on its wetting behavior. As model fluid impurities we consider aqueous solutions of KCl with molar concentrations up to 1.8M. The contact angle is found to decrease weakly with increasing ionic concentration, from 90o at 0M to 81o at 1.8M concentration, and with increasing dipole moments across the nanotube wall from 109o to 93o. The influence of solid impurities, modeled by H and OH groups, is found to be more significant, yet it is dependent on the partial charge distribution on the carbons near the doping site.
Nanotech 2004 Conference Technical Program Abstract