Imbibition by polygonal spreading on microdecorated surfaces

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By Scott Tsai


Courbin et al use micropatterned surfaces to create different final shapes for spreading droplets. They show that they can control the final shape by changing the liquid. They describe a model for the velocity of the contact line, and they also show that the radii of the spreading drops scale with Washburn's scaling.

Wetting On Patterened Surfaces

Fig.1 Schematic of a micropatterened surface and a photograph showing the surface
Most studies on the wetting of patterened surfaces is concerned with increasing the hydrophobicity of the surface via increased roughness. In this study, the authors have focused on hydrophilic surfaces, where the increase in solid surface increases wettability. The paper presentated is concerened with the situation where the resultant contact angle is lower than the equilibrium contact angle of a drop sitting on a surface of the same material, but unpatterened. The authors use regularly patterened surfaces like the ones shown in Fig. 1.

By varying the liquid used and keeping the size of the drops the same, the authors were able to see seven different macroscopic scenarios. As Fig.2 shows, the seven scenarios are (i) a circle around a reservoir, (ii) an octagon around a reservoir, (iii) a square around a reservoir, (iv) a square, (v) an octagon, (vi) a rounded octagon, and (vii) a circle.

Fig.1 Seven different macroscopic scenarios resulting from using different liquids