UPTON, NY-When it comes to designing extremely water-repellent surfaces, shape and size matter. That's the finding of a group of scientists at the U.S. Department of Energy's Brookhaven National Laboratory, who investigated the effects of differently shaped, nanoscale textures on a material's ability to force water droplets to roll off without wetting its surface. These findings and the methods used to fabricate such materials-published online October 21, 2013, in Advanced Materials-are highly relevant for a broad range of applications where water-resistance is important, including power generation and transportation.
"The idea that microscopic textures can impart a material with water-repellent properties has its origins in nature," explained Brookhaven physicist and lead author Antonio Checco. "For example, the leaves of lotus plants and some insects' exoskeletons have tiny-scale texturing designed to repel water by trapping air. This property, called 'superhydrophobicity' (or super-water-hating), enables water droplets to easily roll off, carrying dirt particles along with them."
Mimicking this self-cleaning mechanism of nature is relevant for a wide range of applications, such as non-fouling, anti-icing, and antibacterial coatings. However, engineered superhydrophobic surfaces often fail under conditions involving high temperature, pressure, and humidity-such as automotive and aircraft windshields and steam turbine power generators-when the air trapped in the texture can be prone to escape. So scientists have been looking for schemes to improve the robustness of these surfaces by delaying or preventing air escape.
Creating nanoscale textures
"In principle, the high robustness required for several applications could be achieved with texture features as small as 10 nanometers (billionths of a meter) because the pressure needed for liquid to infiltrate the texture and force the air out increases dramatically wi
|Contact: Karen McNulty Walsh|
DOE/Brookhaven National Laboratory