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Olympic Swimmers Are Using Swimmies After All!Hydrophobic materials such as paints, inks, and emulsions, have mechanical properties that have seemed a little incomprehensible until now. However, Australian researchers have now shown that air bubbles roughly 30 nm in diameter coat the surface of hydrophobic materials immersed in water.These nanobubbles are too small to be imaged via visible light. So, associate professor, Phil Attard and coworker James W. G. Tyrrell of the Ian Wark Research Institute of the University of South Australia had to use atomic force microscopy to particles coated with the nanobubbles. They have shown that the nano-bubbles are very stable indeed and must therefore have a dramatic effect on the mechanical properties of such hydrophobic materials immersed in water. This could be of immense importance in designing the chemistry for mineral separation using froth flotation. This technique separates minerals from raw feedstock based on selective interactions between hydrophobic mineral particles and air bubbles. It would appear that appropriate use of hydrophobic interactive coatings could dramatically improve the efficiency of such techniques. The research also indicates that hydrophobic surfaces immersed in water are almost entirely coated with bubbles. It seems likely that the drag of water flow near hydrophobic materials, such as the fibers used in some Olympic swimsuits, is lower than that of bubble-free surfaces. The water slips over the bubbles instead of attaching by dispersion forces to the polymers of the swim suit. Those swimmers are floating on air when they win their medals. Few of us realized that they were floating on air in the water as well.
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