Science News

Boat made from a sieve

Edward Lear famously wrote about sending the Jumblies to sea in a sieve and many warned they would drown, but perhaps not if they were aboard a miniature boat made by Chinese scientists Qinmin Pan and Min Wang.

The two scientists based at Herbin Institute of Technology describe in the current edition of the ACS journal Applied Materials and Interfaces, how they have produced a water-repelling surface so powerful that a fine copper meshwork bent into a simple boat-shape will float on a bath of water, even when laden with sand "cargo".

The trick relies on chemically cleaning the copper surface and then "functionalising it" by dunking it in a silver solution and then a solution of dodecanoate, a fatty acid.  Studying the treated copper meshwork under an electron microscope reveals that the silver form a system of very fine dendrites (branches) like the leaves of a miniature fern.  The ends of these silver branches become decorated with the dodecanoate, which repels water and traps a layer of air against the mesh,rendering it water-tight.

The researchers admit that scaling the technique up to full-sized boats is probably not practical, but they suggest that this trick could be used for purposes such as underwater robots and underwater surveillance.  The air-film trapped against the mesh, they say, can also dramatically reduce the drag on the hull of their "boat" and so could be used in drag-cutting devices (and that's drag as in resistance, rather than Edna Everage...).

15th Mar 2009