Technology & Science – CBC News – Clean-freak’s dream: Superhydrophobic coatings repel water, dirt.
Nissan painted half of a test vehicle in a superhydrophobic paint. Mud and water just slid off the car. In other tests, rain bounced right off superhydrophobic-coated windshields in severe storms, without the use of the car’s wipers.Nissan painted half of a test vehicle in a superhydrophobic paint. Mud and water just slid off the car. In other tests, rain bounced right off superhydrophobic-coated windshields in severe storms, without the use of the car’s wipers. Courtesy Nissan
Say the name out loud, and it sounds like it comes from Mary Poppins: Superhydrophobics. But get used to the word — it’s about to change thousands of products in the marketplace by giving them the world’s most liquid-resistant coating.
Though superhydrophobes were first created in 1977, they haven’t been used extensively on a commercial scale. But Nissan injected some excitement by painting half a test vehicle in a superhydrophobic paint. Mud and water just slide off the car.
In other tests, rain bounces right off superhydrophobic-coated windshields even in severe storms, without the use of the car’s wipers.
The car maker is the latest to show off the potential of superhydrophobic material, but is hardly the only company trying to harness the idea.
Clayton Berg of Belgian-Canadian firm Nanex has re-engineered the most-common industrial formula of superhydrophobes for use by consumers. There are two types of spray cans — one for absorbent materials, like clothes or furniture, the other for non-absorbent ones, such as car hoods or building materials. Unlike the industrial formula, Nanex’s version does not leave a white film, and most superhydrophobes are very long lasting.
‘We’re essentially mimicking what the lotus leaf does – the lotus effect has this same ability where it’s not just water-repellent. It, in fact, pushes the water away.’– Clayton Berg, Nanex
“You could call it bio-mimicry. We’re essentially mimicking what the lotus leaf does – the lotus effect has this same ability where it’s not just water-repellent. It, in fact, pushes the water away. It does that both to clean itself and keep the large leaves light and not weighed down with water.”
For years, scientists have tried to artificially mirror what the lotus leaf does naturally. There have been many good ideas — top-level fisherman’s raincoats are covered in wax, and water just slides right off. But such a coat is not breathable, which can make it uncomfortable.
Superhydrophobics are different, Berg explains. “This material, because it’s nanotechnology on such a small scale, it’ll actually absorb into the individual fibres and not clog any of the spaces between the fibres, which leaves the breathability.”
Using a microscope, you can see droplets of any liquid simply sit on top of any treated surface, be it a shoe, a rock, or a car. But, Berg points out, it isn’t technically waterproof, which simply refers to blocking the passage of liquid. The chemical composition of a superhydrophobe repels virtually all liquids, similar to how magnets can push against one another.
“The water reacts as though it’s terrified of the surface,” Berg says. “It’ll ball up and get as small as it can away from the surface, and then it will try and run from the surface.”
As a result, Superhydrophobics are often described as self-cleaning. Nissan billed its paint job as the world’s first car that’ll never need a car wash. In fact, it’s not that it cleans itself so much as it refuses to allow dirt to stick.
But car-wash owners need not panic just yet – Nissan has not announced any plans to make its special paint available on its new models. However, the paint could be offered as an aftermarket option that would add several hundred dollars to the price of a new vehicle.
By David Common, CBC News Posted: May 19, 2014 5:00 AM ET via Superhydrophobics could drive water-repelling consumer revolution – Technology & Science – CBC News.