Theoretical Analysis of Contact Angle and Contact Angle Hysteresis of Wenzel Drops on Superhydrophobic Surfaces.

Although understanding the wetting behavior of solid surfaces is crucial for numerous engineering applications, the mechanisms driving the motion of Wenzel drops on rough surfaces remain incompletely clarified. In this study, the contact angle and contact angle hysteresis of Wenzel drops on superhydrophobic surfaces are investigated from a thermodynamic perspective. The free energy of the system is theoretically analyzed, thereby determining the equilibrium contact angle. Based on the sessile drop method, the relationship between the free energy barrier and the drop volume is calculated quantitatively, enabling the determination of advancing and receding contact angles under zero free energy barrier conditions. The theoretical calculations agree well with the experimental data. These findings enhance the understanding of the interfacial interactions between Wenzel drops and superhydrophobic surfaces.