Take a sheet of shrinkable plastic, like the stuff you find in Shrinky Dinks. Add a dash of of Teflon and — voila! — you have an incredibly simple new kind of superhyrdrophboc material. That's pretty much what a team of researchers from the the University of Sydney has done. The team had been playing shrinkable plastics — just like the ones you find in kids craft kits Shrinky Dinks — to make new kinds of gold film. But they also decided to see what would happen if they deposited Teflon onto the surface.
So they did. And after layering the slippery material onto the surface and heating it, they discovered that they'd created a crinkled surface where water rolled straight off, with a contact angle of an impressive 172 degrees. That means the water barely even touches the surface, instead rolling off like a ball down a slope. The research is published in Applied Interfaces and Materials.
That's perhaps not that impressive by itself, because there are many superhydrophobic materials in the world by this point. But the team has discovered that it's also incredibly durable, too. A 10-nanometre-thick layer of Teflon on a polyolefin sheet was found to have the same scratch resistance as an aluminium coating would. And even when it was scratched, it still happily shed the water.
Because the material is inherently easy to make conform to objects — this is, after all, essentially shrink-wrap plastic — it could be used to provide a water-shedding surface to anything, from cars to bags.
Top image: Water beading from a DWR-coated surface (Image by Brocken Inaglory