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Title: Contact angles from Young’s equation in molecular dynamics simulations

In this work, we propose a method to calculate the equilibrium contact angle of heterogeneous 3-phase solid/fluid/fluid systems using molecular dynamics simulations. The proposed method, which combines the phantom-wall method [F. Leroy and F. Müller-Plathe, J. Chem. Phys. 133, 044110 (2010)] and Bennett’s acceptance ratio approach [C. H. Bennett, J. Comput. Phys. 22, 245 (1976)], is able to calculate the solid/fluid surface tension relative to the solid surface energy. The calculated relative surface tensions can then be used in Young’s equation to estimate the equilibrium contact angle. A fluid droplet is not needed for the proposed method, in contrast to the situation for direct simulations of contact angles. In addition, while prior free-energy based methods for contact angles mainly focused on the wetting of fluids in coexistence with their vapor on solid surfaces, the proposed approach was designed to study the contact angles of fluid mixtures on solid surfaces above the fluid saturation pressures. Using the proposed approach, the contact angles of binary Lennard-Jones fluid mixtures on a non-polar solid substrate were calculated at various interaction parameters and the contact angle of water in equilibrium with CO 2 on a hydrophilic polar silica surface was obtained. For both non-polar andmore » polar systems, the calculated contact angles from the proposed method were in agreement with those obtained from the geometry of a cylindrical droplet. The computational cost of the proposed method was found to be comparable to that of simulations that use fluid droplets, but the new method provides a way to calculate the contact angle directly from Young’s equation without ambiguity.« less
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [1]
  1. Princeton Univ., NJ (United States). Dept. of Chemical and Biological Engineering
  2. Princeton Univ., NJ (United States). Dept. of Chemical and Biological Engineering; Technical Univ. of Darmstadt (Germany). Eduard Zintl Inst. of Inorganic and Physical Chemistry
Publication Date:
Grant/Contract Number:
SC0002128; AWD 1004131
Type:
Accepted Manuscript
Journal Name:
Journal of Chemical Physics
Additional Journal Information:
Journal Volume: 147; Journal Issue: 8; Journal ID: ISSN 0021-9606
Publisher:
American Institute of Physics (AIP)
Research Org:
Princeton Univ., NJ (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Oceanic and Atmospheric Administration (NOAA), Boulder, CO (United States); German Research Foundation (DFG)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; 74 ATOMIC AND MOLECULAR PHYSICS; Lennard-Jones fluid; chemical compounds and components; surface energy; fluid flows; chemical elements; liquid solid interfaces; fluid systems; molecular dynamics; free energy; electrostatics
OSTI Identifier:
1474037
Alternate Identifier(s):
OSTI ID: 1377981