Roughness Geometry on Wettability and Wetting Dynamics

Wetting States on Model Rough PDMS Surfaces. The surface properties of all model bumpy and cavity PDMS surfaces were studied by static and dynamic contact angle measurements with water as the test liquid and the data are tabulated in Table 4.3. The contact angle data for the smooth PDMS surface are included as reference. As discussed in Sect. 4.1, wetting of liquid on a rough surface can be described by 

The overall results in Table 4.3 show that the observed 0 for the model rough PDMS surfaces (columns 5 and 9) are not in agreement with neither dyj nor cb 

Wenzel equation can be derived based on the geometry of the contact line (Fig. 4.10), 

After rearranging the above equation to the classical Wenzel format, the effective roughness ratio (r is obtained and is given by  

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