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Bottom-up nanotechnology with metals and polymers

Producing highly porous nanostructures made from metal is difficult because metal atoms are unhappy in structures having very high surface areas. By coating metal nanoparticles with organic molecules and using a block co-polymer as a scaffold, a novel nanotech procedure produces metal nanostructures containing uniform hexagonal pores about 10 nm across that could supply new catalysts, faster metal wires for microchips, and better optical materials. From the National Science Foundation, via AAAS EurekAlert “Metals shape up with a little help from friends“:

New method ‘self-assembles’ metal atoms into porous nanostructures

For 5,000 years the only way to shape metal has been by the “heat and beat” technique. Even with modern nanotechnology, metalworking involves carving metals with electron beams or etching them with acid.

Now Cornell researchers have developed a method to self-assemble metals into complex configurations with structural details about 100 times smaller than a bacterial cell by guiding metal particles into the desired form using soft polymers.

“I think this is ingenious work that takes the fundamental concepts of polymer science and applies them to make metals in a totally novel way,” said Andrew Lovinger, the director of the Polymers Program at the National Science Foundation. “In so doing, it opens the door to all kinds of new possibilities.”

Applications include making more efficient and cheaper catalysts for fuel cells and industrial processes, and creating “plasmonic” surface structures capable of carrying more information across microchips than conventional wires do.

“The polymer community has tried to do this for almost 20 years,” said Uli Wiesner, Cornell professor of materials science and engineering, who reports on the new method in the June 27, 2008, issue of the journal Science [abstract]. “But metals have a tendency to cluster into uncontrolled structures.”

…In addition to making porous materials for catalysis, the researchers said, the technique could be used to create finely structured metals on surfaces, a key to transform the field of plasmonics, which studies the interactions among metal surfaces, light, and density waves of electrons, known as plasmons. Currently, researchers are investigating the use of plasmons to transmit more information across metal wires in microchips and to improve optics applications, like lasers, displays, and lenses.

—Jim

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