Understanding the Role of Surface Microgeometries on Wetting: Designing Robust Superhydrophobic Surfaces
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Abstract
This thesis is concerned with effects of surface microgeometries on wetting, aiming at providing instructions for reproducing controllable wettability on artificial surfaces and designing robust superhydrophobic surfaces. First, the origin of edge effect is understood by a thermodynamic approach for the analysis of energetic state of drops on a single pillar. A wetting map in terms of edge angle and intrinsic contact angle is provided for designing microstructures to prevent drop collapse/spilling over the pillar. Secondly, wetting transitions on various microstructured surfaces (i.e., arrays of pillars) has been understood by a first-principle thermodynamic model. Effects of surface parameters, i.e., intrinsic CA, edge angle and length scale factor, on wetting stability has been revealed. Finally, an experimental study on the application of superhydrophobic surfaces in low-temperature conditions is carried out by using differential scanning calorimetry and a thermoelectric cooler. Effects of various factors responsible for drop freezing have been systematically investigated.