Researchers at the University of Rochester have just created a metal that is unable to sink in water, no doubt after watching a rerun of Titanic. The metal they created is so waterproof that, no matter how many punctures it receives, it will still float on top of water. The products that could be created with this metal are potentially groundbreaking: unsinkable ships, a wearable flotation device that can float after being punctured, monitoring devices that can float in the ocean for years.
The original technique developed for this metal was to use femtosecond bursts of lasers to etch the surfaces of the metals with intricate micro and nanoscale patterns that trap air inside them. These make the surface of metal superhydrophobic (water repellent). The researchers found, however, that after this metal was left in water for a period of time, the metal began to lose it's waterproof qualities.
So the researchers looked to nature for the answer. Spiders and fire ants, both of which have superhydrophobic bodies, are able to survive long periods on the surface of, or submerged in, water. But how? Each species does it a little differently: Argyroneta aquatica spiders created a dome-shaped web underwater which they fill with air carried from the surface between their legs and abdomens. Fire ants form rafts by trapping air between their superhydrophobic bodies.
The researchers, inspired by spiders and fire ants, created a structure that is able to trap air inside it, thus achieving complete buoyancy. Even after the metal had been submerged in water for two months, it bounced back up to the surface when released.
Although aluminium was used for this project, the team stated that any metal, and many other materials, could be used to 'etch' the waterproof design onto it. The possibilities that this product could create are endless. We probably won't have any more blockbuster films about ships sinking, but at least we still have Titanic.
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