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patella.whack writes:

Science Daily has an interesting article which focuses on a new understanding of how surfaces deflect water and the engineering of correct surface roughness to trap the vapor that provides dryness when submerged.

Understanding how the surfaces deflect water so well means the valuable feature could be reproduced in other materials on a mass scale, potentially saving billions of dollars in a variety of industries, from antifouling surfaces for shipping to pipe coatings resulting in lower drag.

The research team is the first to identify the ideal "roughness" needed in the texture of a surface to keep it dry for a long period of time when submerged in water. The valleys in the surface roughness typically need to be less than one micron in width.

Samples with the nanoscale roughness remained dry for up to four months, the duration of the experiment. Other samples were placed in harsh environments, where dissolved gas was removed from the ambient liquid, and they also remained dry.

Historically, scientists had not understood how to keep water vapor from succumbing to condensation within the pore, which can cause water to wet the surface. But the Northwestern team found the molecular key: They demonstrated that when the valleys are less than one micron in width, they can sustain the trapped air as well as vapor in their gasified states, strengthening the seal that thwarts wetness.

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