for National Geographic News
Copper mesh coated with a highly water repellent material can float extremely well, according to researchers in China who built stamp-size prototypes.
The "boats" even stay afloat "when the upper edges are just a hair below the surface of the water."
The boats, made out of the superhydrophobic mesh, appear to be among the most buoyant ever constructed, noted study co-author Qinmin Pan, a chemist at the Harbin Institute of Technology.
"In fact, these boats are able to carry a load exceeding the maximal capacities calculated from the boat's volume," Pan said in an e-mail interview.
The coating, made of silver nitrate and other chemicals, creates an "air film" around the copper mesh, which prevents direct contact with water.
"The presence of air film increases the water displace-volume of boats to a certain extent, leading to a large loading capacity," Pan said.
The film also prevents water from seeping through the mesh.
Since the copper mesh is flexible, Pan said, scaling up the technology to carry humans would be "problematic."
The researchers instead envision small-scale applications such as aquatic robots for environmental surveillance. (See "Robot Fish to Detect Ocean Pollution.")
And since the water-repellant material may make it easier for the boats to move through water, Pan said, "the present finding may be extended to the design of novel superfloating and drag-reducing—fast moving—aquatic devices."
Findings published in the February 25 issue of the journal Applied Materials and Interfaces.
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