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Imagine a mesh that instead of letting water in repelled it so much that a life preserver made from it would support a horse. Scientists at the Harbin Institute of Technology in China created such a mesh out of copper wires 200 microns thick and pores about that size or smaller. They dunked the lattice first in silver nitrate solution and then in acid, which deposited the silver onto the copper as leaflike structures seven microns high. Like the hairs on the underside of the great diving beetle Dytiscus marginalis, the silver leaves trap a film of air, thereby making the meshes superwater-repellent.
Postage-stamp-size boats made of these lattices could hold three times as much sand as ones made from untreated meshes, and they still floated even when their upper edges dipped below the water's surface. Although the scientists admit that applying their superbuoyant technology to full-size ships would be unlikely—the hydrophobic repulsion is probably too weak for large vessels—they note it could lead to a new generation of miniature aquatic robots. Their work surfaces in the February 25 Applied Materials & Interfaces.
