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An aqueous environment may have a major effect on wettability and adhesion. First, the sensitivity of underwater wetting of a smooth surface to the surface energy of the solid is discussed. Then, the effect of surface roughness is presented. Roughness of a solid surface and the fluid in which it is immersed may lead to extreme cases of wetting: from complete adhesion of the liquid to the solid on the one hand to super-hydrophobicity (non-wetting) on the other. The effect of roughness on wetting in air is described, and it is shown under what conditions the situation can turn from complete wetting to super-hydrophobicity. The next stage in the analysis is adhesion of organic liquids to solid surfaces in an aqueous environment. It is shown that underwater super-hydrophobicity is feasible, and the condition for its stability is presented. |