Universality in the dependence of the drop contact angle on liquid-solid interactions and temperature obtained by the density functional theory
Department of Chemical and Biological Engineering, State University of New York at Buffalo, Buffalo, NY 14260, USA
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Revised: 15 June 2011
Published online: 30 August 2011
A nonlocal density functional theory is employed to calculate the contact angles of nano- and macrodrops on smooth solid surfaces in wide ranges of temperature and parameters of the Lennard-Jones potentials representing the fluid-fluid and fluid-solid interactions. For both types of drops, simple linear dependencies of the contact angle on the fluid-solid energy parameter ∊fs was found for various temperatures and hard core fluid-solid parameters σfs. Expressions are suggested that relate the contact angle θ to the parameters of the interaction potentials and temperature. The most intriguing feature was that for each considered σfs there is a value ∊0fs of ∊fs for which the contact angle θ = θ0 becomes independent of temperature and of σfs. It is shown that ∊fs = ∊0fs divides the materials for which θ increases from those for which θ decreases with increasing temperature.
© EDP Sciences, Springer-Verlag, 2011