Wetting and electro-wetting behaviors of [Bmim] [Bf4] ionic liquid droplet on lyophobic and lyophilic solid substrates

Abstract

Molecular dynamic simulation was adopted to explore the wetting and electro-wetting behavior of nano-droplet of ionic liquid on a silicon solid substrate and the effect of solid wettability and temperature on the wetting phenomenon. Results indicate that the equilibrium contact angle decreases with the increase of solid wettability and temperature, and the effect of temperature is more obvious while IL droplet wets a lyophilic surface. The droplet undergoes an asymmetric electro-wetting on the lyophobic surface with energy parameter ε = 0.1 kcal/mol under the applied positive and negative electric field in vertical direction. And this asymmetry diminishes gradually with the increase of ε and almost disappears when ε = 3.0 kcal/mol because of the strong solid attraction. Through analyzing the number density of coarse particles, the redistribution of cationic and anionic particles on the first wetting layer is the main factor dominating the wetting behaviors.