Surface Wetting Study via Pseudocontinuum Modeling
M Makaremi and MS Jhon and MS Mauter and LT Biegler, JOURNAL OF PHYSICAL CHEMISTRY C, 120, 11528-11534 (2016).
An accurate estimation of contact angle and surface wettability for various degrees of hydrophobicity becomes increasingly important in the molecular design of solid surfaces. In this study, we develop a simple, yet physically realistic, model for estimating contact angle via hybridizing molecular dynamics and pseudocontinuum theory. Molecular dynamics simulations were carried out to compute the macroscale contact angle between a water droplet and smooth walls from the nanoscale calculations. A macrolevel droplet including numerous degrees of freedom due to a large number of molecules cannot be directly studied using atomistic simulations. To resolve this issue, we employed two approaches consisting of the pseudocontinuum approximation and the modified Young- Laplace equation. The former involves the 9-3 Lennard-Jones potential and can drastically reduce the degrees of freedom in molecular simulations, while the latter relates the mesoscale contact angle to the realistic one. We altered different parameters, including the liquid- surface potential characteristics and the temperature, and calculated the water contact angle by leveraging the mass density profile fitting method to predict a broad spectrum of hydrophobic and hydrophilic substrates. The computational results were compared with experimental data for various materials, including graphite, silicon, and metals. This study suggests that pseudocontinuum modeling is an accurate approach to probe surface wettability for various processes at a low computational cost.
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