Effect of water molecules on nanoscale wetting behaviour of molecular ethanol on hydroxylated SiO₂ substrate

Abstract

The wettability property of silica (SiO₂) substrate by the ethanol molecules may play important roles in nanomedicine and nanomaterials fabrication. In this paper, by molecular dynamics (MD) simulations, we show that ethanol molecules can form an ordered monolayer on hydroxylated β-cristobalite SiO₂ (1 1 1) substrate, therefore an ethanol droplet can form on this ordered monolayer. We found that water molecules could affect the formation of ethanol monolayer on SiO₂ surface when the amount of water molecules is large, thus regulates the wetting transformation of ethanol molecules. The absorbed water molecules would disrupt the ordered ethanol monolayer and the ethanol molecules could not form the droplet.

Keywords:

• Wetting behaviour
• ethanol
• SiO₂
• molecular dynamics

Acknowledgments

We gratefully acknowledge valuable discussions with Prof. Haiping Fang.