Anti-wetting materials have the potential for dramatic performance improvements in many applications such as drag reduction for marine vehicles and fluid power systems, anti-fouling & icing on aircraft and wind turbines, and stain-resistant coatings. The degree to which a solid surface repels a liquid mainly depends upon two factors: surface energy and surface morphology. The surface energy affects the liquid-solid surface interface by influencing the attractive forces between the liquid and solid at the molecular scale. Surface morphology alteration, on the other hand, at the micro- and/or nanoscale can allow for an air layer to be maintained in the space between the asperities during liquid contact. Known as the lotus effect, this result can significantly reduce droplet and fluid flow resistance and it has been successfully employed in creating an array of superhydrophobic and even superoleophobic surfaces. Recently, a team from the University of Virginia (Ph.D. Candidate Adam Steele, Dr. Ilker Bayer, and Prof. Eric Loth) fabricated the first superoleophobic coatings by spray-casting nano-particle/polymer suspensions. The coatings can be applied to large and/or flexible substrates with ease and are being investigated for their use in wind turbine blades to help prevent fouling and icing and in energy systems to promote heat transfer in multiphase flows. This work is being funded by AREVA and the National Science Foundation. Additional information is available at nanotexture.tumblr.com.
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