Analysis of Dynamic Wetting and Dewetting on a Hydrophobic Surface Using Molecular Kinetic Theory

Abstract

The dynamic wetting and dewetting of a water droplet on a hydrophobic solid surface with an equilibrium contact angle of approximately 100° was investigated using molecular kinetic (MK) theory to model the extension–contraction experiment and numerically calculate the radius of the contact line circle between the solid and liquid, contact line velocity, and dynamic contact angle. Furthermore, the numerical calculation results were examined in terms of various coefficients of the contact line friction to evaluate the mobility of the contact line. The calculation results of wetting and dewetting were in quantitative agreement with our previous experimental results, indicating that our constructed model was appropriate. Therefore, the MK theory can be applied to explain the characteristics of dynamic wetting and dewetting of droplets on hydrophobic surfaces, as with hydrophilic surfaces.

Keywords

• dynamic wetting
• dynamic dewetting
• hydrophobic surface
• water droplet
• molecular kinetic theory
• contact line
• contact line circle