Wettability of a nano-droplet in an electric field: A molecular dynamics study

DY Zong and Z Yang and YY Duan, APPLIED THERMAL ENGINEERING, 122, 71-79 (2017).

DOI: 10.1016/j.applthermaleng.2017.04.064

The wettability of water droplets on solid substrates with external electric fields is a driving mechanism in many technologies. Here, the wettability of water nano-droplets on Si (1 0 0) substrates subjected to a perpendicular electric field was studied using molecular dynamics simulations (MD). The effects of the electric field on the liquid-vapor and solid-liquid interfacial tensions were investigated. The simulations show that the water contact angle decreases with increasing electric field on the Si (1 0 0) substrate. The MD results also show that the liquid-vapor interfacial tension decreases slightly with electric field strength and is insensitive to the field direction. However, the solid- liquid interfacial tension is significantly affected by the field direction and decreases in an upward but increases in a downward electric field. This directionally dependent solid-liquid interfacial tension causes the contact angle of the water droplet in a downward electric field to be larger than that in an upward electric field with the same field strength. The wettability of the solid surface also affects the effects of the electric field. For a hydrophobic substrate, the contact angle decreases with the field strength while for a hydrophilic substrate, the contact angle increases with increasing field strength. (C) 2017 Published by Elsevier Ltd.

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