Image: Nanofilm
A photomicrograph shows a cross-section of the layered plastic material, built up from a gluelike polymer solution and a dispersion of clay nanosheets. The arrows indicate the thickness of the material: about 1.5 microns, or less than a tenth the width of a a human hair.
updated 10/12/2007 3:32:02 PM ET 2007-10-12T19:32:02

By mimicking structures found in seashells, scientists have created a transparent plastic that is as strong as steel.

For years scientists have tried to build sturdy materials for larger products from ultrastrong nano-size building blocks, such as nanotubes, nanosheets and nanorods, only to have the larger structures turn out comparatively weak.

"When you tried to build something you can hold in your arms, scientists had difficulties transferring the strength of individual nanosheets or nanotubes to the entire material," said study leader Nicholas Kotov of the University of Michigan.

To solve this problem, Kotov and his colleagues have devised a process that builds materials one nanoscale layer at a time, similar to the way that mother-of-pearl, the iridescent lining of mussel, oyster and other mollusk shells, is built.

They built a machine that dips a piece of glass about the size of a stick of gum alternately into a gluelike polymer solution and a dispersion of clay nanosheets. These materials form cooperative hydrogen bonds with each other across the layers, which give rise to a "Velcro effect," Kotov explained.

This effect, coupled with the arrangement of the nanosheets in a brick-and-mortar structure, make the final product (as thick as a piece of plastic wrap) very strong. The developers say that the product could be widely available in a relatively short period of time.

"The technology of preparation of these materials is pretty simple," Kotov told LiveScience. "So, if someone decides to make it happen, it could be available on the market in a year or less."

The process is detailed in the Oct. 5 issue of the journal Science.

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