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The following may be involved: The more synclastically curved a surface is, the lesser area of it is required to accumulate a given force per unit length of periphery because the lay of the surface deviates from flatness over a shorter distance. Therefore, if a sphere of liquid encounters a hydrophobic surface that is flat, that deforms the surface the same as does placing a basketball on the floor, resulting in tighter curvature in certain areas that repels it from the floor enough to stabilize it there. However, if you take the same basketball and place it on a surface having irregularities that are substantial but smaller than the diameter of the ball, and try to force the ball into the same amount of contact that it had with the flat surface, it will resist more vigorously because the curvature required to make it conform to the surface is greater. That suggests that hydrophobic liquids will tend to have less contact with a rough surface than a smooth one at any given pressure, because the surface tension resists deforming so as to match the roughness.As for hydrophilic surfaces: Because they tend to attract the liquid, the liquid will tend to cover the surface. It is energetically favorable for the liquid to contact the entire surface rather than just the high points of it, which it will try to do. But there is also the issue of the surface tension on the exposed side of the liquid. The liquid will try to keep that surface flat. The volume of the available region is determined by the thickness of the region of roughness. If the amount of liquid is less than this volume, it will not be able to assume a fully flat surface on the outside, and will develop a negative pressure (relative to the environment) because of the conflict, and if additional liquid becomes available, it will be pulled into the system as the system tries to flatten its outside surface. Thus, the rough surface will tend to adsorb liquid until its roughness is filled. On a flat (smooth) hydrophilic surface, of course there is no roughness and therefore no roughness volume, so there is no energy advantage for a thin layer of liquid more than several molecules thick to become thicker.
Within a given boundary, a rough surface will have a greater area of exposed material than a smooth surface. Hydrophilic and hydrophobic behaviors are surface interactions.More area = more interaction.