Features Friday, November 28, 2014 - 05:30
The News Minute | November 28, 2014 | 3:00 pm IST Scientists have created the most non-stick surfaces yet, using microscopic liquid-repellent structures instead of plastic coatings like Teflon. These new surfaces could help protect medical implants from gunk that can build up on and ruin the devices, endangering patients, showed research. Natural materials like insect wings and duck feathers are water-repellent or hydrophobic, whereas many others are oleophobic, meaning they repel oil. A number of materials, such as Teflon, are both hydrophobic and oleophobic, which degrade at high temperatures, which limits their use. Now, scientists have developed a way to render many different materials super-repellent to both water and oil without using coatings. "Usually artificial surfaces repel water because of the chemical composition of the material, but in our case, the repulsion is completely by mechanical means," said Chang-Jin Kim, study co-author and mechanical engineer at University of California, Los Angeles. Scientists have discovered that super-hydrophobic objects, such as lotus leaves, are often covered in microscopic bumps so that droplets float on top. "This could also have biomedical applications - you won't have unwanted substances building up on surfaces anymore in the body," Kim was quoted as telling Livescience. The researchers started with silica and etched a "bed of nails" structure onto it, with each nail head measuring 20 microns wide, or about one-fifth the average width of a human hair. These newly developed surfaces repelled not just oil and water, but also fluorinated solvents, which are liquids with the lowest surface tension known. Without a plastic coating, the super-repellent silica could withstand temperatures more than 1,000 degrees Celsius. These super-repellent materials can last longer in outdoor environments and industrial settings than traditional super-repellent materials. The study appeared online in the journal Science. IANS
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