Scientists Say They Have Found a Way to Outsmart Rain

A team of MIT engineers say they’ve discovered the most waterproof material ever, and it has the potential to bring about a drier future, free from the personal nuisance and industrial disadvantages of precipitation.

If you're thinking, right, heard that one before, you're not alone. Remember NeverWet? It’s the mostly-waterproof silicon coating that inspired headlines like The Magical, Water-Repelling Spray Is Kind of Amazing, and soon after, more sour headlines like NeverWet? More Like OftenKindaWet.

This is different—and au naturel, researchers say. Until now, waterproofing sprays relied on chemicals to repel the moisture. But the MIT team, led by Prof Kripa Varanasi, has discovered an approach that takes a cue from nature.

The engineers found a way to cut the amount of time by half that a water droplet is in contact with the hydrophobic surface it’s being repelled from. The time it takes a drop of water to bounce off the surface after it hits is a limitation scientists previously tried to work around, rather than eliminate. The new technique reduces the bounce time by 40 percent, researchers say. They published their findings in the journal Nature yesterday.

The approach is crazy simple. The scientists used a textured surface with tiny ridges that causes droplets to break into smaller drops when they hit instead of flattening like a pancake. Logically, smaller drops can bounce off a surface faster than a pancake-like puddle taking up a larger amount of surface area. It worked.

They used a high-speed camera to film the phenomenon (the droplet action starts at 0:32):

As the video explains, it’s the same principle that makes gossamer butterfly wings or nasturtium leaves repel raindrops—an always-fun reminder that even in one of the world's most high-tech institutions, nature got to the answer first.

Next step, the engineers have to figure out how to combine the fragile micro-textured material with durable fabrics so people can wear the super-repellant clothing. They believe that obstacle can be overcome, which conjures up images of future-humans casually strolling through a downpour as tiny droplets scatter off their next-gen raincoat. "What will be the next Gore-Tex?" Varanasi waxed in an interview with the BBC.

The reduced contact time also means the droplets are whisked from the repellant surface before there's time to freeze, which is good news for a host of reasons. Think about coating structures—airplanes, power lines, windmills and so on—with a hyper-waterproof material that could stave off corrosion caused by rain or ice. That could have significant implicates for the energy and travel industries, assuming it’s not another case of scientists crying wolf.

@meghanneal