The coating is a mixture of cross-linked "polydimethylsiloxane," or PDMS, and liquid-resisting nanoscale cubes developed by the Air Force that contain carbon, fluorine, silicon and oxygen. While the material's chemistry is important, so is its texture, because it hugs the pore structure of whatever surface it is applied to, and creates a fine web of air pockets within those pores, so any liquid that comes in contact with the coating is barely touching a solid surface.
According to Dr. Tuteja, when an untreated surface and a liquid get in close proximity, "they imbue a small positive or negative charge on each other, and as soon as the liquid comes in contact with the solid surface, it will start to spread.we've drastically reduced the interaction between the surface and the droplet." By effectively eliminating the contact between the treated surface and the liquid, there is almost no incentive for the liquid to spread, as such, the droplets stay intact, interacting only with molecules of themselves, and maintaining their spherical shape.
The research team has tested more than 100 liquids and found only two that were able to penetrate the coating: they were both chlorofluorocarbonschemicals used in refrigerators and air conditioners. In Tuteja's lab demonstrations the surface repelled coffee, soy sauce and vegetable oil, as well as toxic hydrochloric and sulfuric acids, and the surfaces are also resistant to gasoline and various alcohols.
This program is of particular interest to the Air Force and the Department of Defense, as it can be useful for self-cleaning su
|Contact: Robert White|
Air Force Office of Scientific Research