Dec 9 2008
A nanotech technique that can coat any number of common fabrics with a layer of silicone nanofilaments appears ready to produce durable, completely waterproof clothing. From News Scientist, written by Jon Evans “Nanotech clothing fabric ‘never gets wet’“:
If you were to soak even your best raincoat underwater for two months it would be wet through at the end of the experience. But a new waterproof material developed by Swiss chemists would be as dry as the day it went in. Lead researcher Stefan Seeger at the University of Zurich says the fabric, made from polyester fibres coated with millions of tiny silicone filaments, is the most water-repellent clothing-appropriate material ever created.
Drops of water stay as spherical balls on top of the fabric … and a sheet of the material need only be tilted by 2 degrees from horizontal for them to roll off like marbles. A jet of water bounces off the fabric without leaving a trace …. The secret to this incredible water resistance is the layer of silicone nanofilaments, which are highly chemically hydrophobic.
The spiky structure of the 40-nanometre-wide filaments strengthens that effect, to create a coating that prevents water droplets from soaking through the coating to the polyester fibres underneath. “The combination of the hydrophobic surface chemistry and the nanostructure of the coating results in the super-hydrophobic effect,” Seeger explained to New Scientist. “The water comes to rest on the top of the nanofilaments like a fakir sitting on a bed of nails,”