3-D thermodynamic analysis on wetting behavior of superhydrophobic surfaces

Abstract

Superhydrophobic surfaces have attracted much interest from experimental researches due to their special properties. Various researches to prepare these surfaces have been reported. However, the thermodynamic mechanisms of superhydrophobicity affected by surface roughness have not been understood completely. In this paper, a 3-D square pillar-textured surface model is chosen to investigate the thermodynamic mechanism responsible for contact angle (CA), contact angle hysteresis (CAH) and free energy barrier (FEB). The effects of pillar height on CA, CAH and FEB, as well as the transition between noncomposite and composite states are obtained, and the calculated results are essentially consistent with the results of theoretical calculations and experimental investigations. Additionally, the scope of application of the 3-D models is further extended to any pillar-textured surfaces with arbitrary shaped cross-sections. The present approach could provide a theoretical guidance for designing superhydrophobic surfaces.