Effects of fluid–solid interaction strength on wetting of graphite-like substrates by water: density functional theory

Abstract

We have explored wetting of graphite-like substrates by water using density functional approach for classical associating fluids. The four-site fluid water model without electrostatic interactions has been taken from Clark et al. [Molec. Phys. 2006, 104, 3561]. The fluid–solid potential is assumed to have a 10-4-3 functional form. The interaction strength is considered as a free parameter. The growth of water film on the substrate upon changing chemical potential is described. The wetting and prewetting critical temperatures, as well as the prewetting phase diagram are evaluated for different fluid–solid attraction. Moreover, the temperature dependence of the contact angle is obtained from the Young equation. It yields estimations for the wetting temperature as well. Theoretical findings are compared with experimental results and with data from computer simulations. The theory is successful and quite accurate in describing the wetting temperature and contact angle changes with temperature and fluid–substrate attraction. Moreover, it provides tools to study other associating fluids on solids of importance for chemical engineering easier, in comparison to experiments and computer simulations.