If you find fingerprint-resistant phones utterly fascinating, then this is going to do your head in. Researchers at the University of Michigan have developed a nanoscale coating that doesn’t just resist liquids, it shuts them down completely. So, instead of droplets going “splat”, they go “boing”… to put it in scientific terms.
It’s not just water that slides off the coating. In the video, it’s shown to easily repel soy sauce, oil and coffee and if that wasn’t impressive enough, it completely disregards petrol, many alcohols and sulfuric and hydrochloric acid. Some 100 fluids were thrown at it, with only two getting through, both being types of chlorofluorocarbons, otherwise known as CFCs.
The secret to the coating is that it’s mostly air — anywhere between 95 to 99 per cent, according to Anish Tuteja, an assistant professor at the university and corresponding author of the paper on the technology (entitled “Superomniphobic Surfaces for Effective Chemical Shielding”, if you’re curious).
The rest is made up of “polydimethylsiloxane”, which is described by the university’s press release as “liquid-resisting nanoscale cubes … that contain carbon, fluorine, silicon and oxygen”. It mentions we have the US Air Force to thank for development of these cubes.
As for the scientific principles behind why the coating works, I’ll leave that to Tuteja and the release to explain:
“Normally, when the two materials get close, 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,” Tuteja said. “We’ve drastically reduced the interaction between the surface and the droplet.”
With almost no incentive to spread, the droplets stay intact, interacting only with molecules of themselves, maintaining a spherical shape and literally bouncing off the coating.
Who knows, maybe in a few years we’ll be dropping our phones into vats of acid just for laughs.