Theoretical Research of Wetting Transition from Cassie State to Wenzel State

Abstract

When droplets touch surface, they may cause different wetting states--Cassie state or Wenzel state, depending on the structure and texture of the surface, the size of the droplet, etc. And the wetting transition from Cassie to Wenzel state has been studied by lots of scientists for its high value in the superhydrophobic field. This work focuses on the mechanism of the wetting transition. It analyses the stress condition of the gas-liquid interface, providing a theoretical result of the wetting transition. The results show that there are four forces acting on the interface during the wetting transition and in the depinning process only one of which changes with time and the other remains unchanged. Moreover, this work provides the speculation of the possible cause of meniscus collapse (touch-down) with an asymmetric configuration. Since wetting transition occurs at the nanoscale, it might be influenced by the potential field, resulting in symmetry breaking which leads to asymmetric representation. Although this work is just a theoretical analysis, it provides a different perspective to the study of wetting transition and we anticipate this assay could offer reference to the research in the superhydrophobic field.