Structure and property analysis for a fractal superhydrophobic surface model

Superhydrophobicity depends mainly on the microstructures of a surface. Although the superhydrophobic surfaces (SHS) have been fabricated, micro-mechanisms responsible for its contact angle hysteresis (CAH) and free energy barrier (FEB) still need to be deeply investigated. For this reason, we attempt to compare the superhydrophobicity of the different hierarchy for the SHS based on a three-dimensional (3-D) pillar model by a more practical thermodynamic method. Therefore, general relationships between the superhydrophobic property and the proposed surface microstructures are also established based on the CAH phenomena together with a transient equation for describing the relationships between advancing/receding CAs and the static apparent CAs. The simulation suggests that the superhydrophobicity of two-step/three-step surfaces is significantly/slightly improved in comparison with those of one-step/two-step surfaces respectively; therefore designing for a three-step surface is again unnecessary. (C) 2015 Elsevier B.V. All rights reserved.