Theoretical Consideration of Wetting in Cassie-Baxter State on Multi-Pillar and Multi-Hole Surfaces: Thermodynamics and Laplace Pressure

抄録

Wetting in Cassie-Baxter state on multi-pillar and multi-hole surfaces is discussed in terms of Gibbs free energy. To discuss thermodynamic stability, free-energy differences before and after the wetting are formulated. However, no difference between the Cassie-Baxter states on multi-pillar and multi-hole surfaces is found. Furthermore, Laplace pressure generated by pillars or by a hole is discussed to find the conditions to prevent the penetration of water into the space between the pillars and the hole. As a result, it is predicted the condition in which multi-hole surface easily generates higher Laplace pressure than multi-pillar surface and easy to prevent the penetration. In other words, it is found that the multi-hole surface is a promising way to generate the Cassie-Baxter state.