Effect of surface topology on the wettability of superhydrophobic surfaces

Abstract

In this paper, we develop a numerical model capable of predicting the apparent contact angle and the wetting state of liquid droplets on superhydrophobic surfaces using Surface Evolver. Specifically, our work investigates the effect of microscopic surface topology on contact angle and the state of wettability. Accordingly, surfaces with four different pillar geometries were investigated: square, cylindrical, parabolic, and conical. The performance of superhydrophobic surfaces was also tested for different solid-liquid material combinations. Our results reveal that cylindrical pillars prevent the transition from Cassie-Baxter to Wenzel wetting state at lower Young contact angles. Furthermore, superhydrophobic surfaces lose their repellency against organic liquids. Nonetheless, a surface with inverted conical pillars is both superhydrophobic and superoleophobic.

Graphical Abstract

Keywords:

• Superhydrophobicity
• Superoleophobicity
• Contact Angle
• Surface Evolver
• Cassie-Baxter Wetting State

Acknowledgments

The authors would like to acknowledge the financial support of the Natural Sciences and Engineering Research Council (NSERC) of Canada. The authors are also grateful to Prof. Kenneth Brakke for his clarifications of some aspects of Surface Evolver and the respected reviewers for their constructive remarks.

Additional information

Funding

Natural Sciences and Engineering Research Council of Canada.