Spray-on waterproof nano coating exceeds expectations

In a video released by the Australian National University, PhD student William Wong can be seen pouring a blue liquid onto a Petri dish. The remarkable thing is that, although the Petri dish is almost full of the liquid, two round coins placed in its centre stay perfectly dry. In fact, every drop that touches the coins immediately slides away and joins the bulk of the surrounding liquid.

The two coins are covered with the material developed by Wong and his supervisor Associate Professor Antonio Tricoli.

"The surface is a layer of nanoparticles, which water slides off as if it's on a hot barbecue," said Wong, adding that the water-repelling material can be applied onto any sort of material including paper, plastics, glass, metal, bricks or wood.

Consisting of two types of plastics – one flexible, the other more robust – the material, the researchers say, is much more durable than other technologies currently used for water-proofing.

"It's like two interwoven fishing nets, made of different materials," Wong said.

The researchers are already envisioning a broad range of applications. Thanks to its transparent nature, the material would be ideal for the water-proofing of mobile phones or skyscraper windows. It could also be used to protect airplanes from ice build-up and boat hulls from corroding. The material's resistance to ultraviolet radiation is an added bonus.

The team developed two ways of creating the material, both of which are cheaper and simpler than processes for manufacturing existing water-repelling materials.

One method uses a flame to generate the nanoparticle constituents of the material. For lower temperature applications, the team dissolved the two components in a sprayable form.

In addition to waterproofing, the new ability to control the properties of materials could be applied to a wide range of other coatings.

"A lot of the functional coatings today are very weak, but we will be able to apply the same principles to make robust coatings that are, for example, anti-corrosive, self-cleaning or oil-repellent," said Wong.