Fighting flames with greener (nano)materials

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http://www.sciencenews.org/view/generic/id/333924/title/Fighting_flames_with_greener_materials

Fighting flames with greener materials

New flame retardants rely on alternating nanolayers of relatively nontoxic materials

By Janet Raloff
Web edition : Wednesday, August 31st, 2011

Materials scientists in Texas have developed flexible coatings mere billionths of a meter thick that keep cotton clothing from going up in flames and plastic foam from melting. Unlike the widely used but potentially toxic flame retardants they've been designed to replace, these nano-coatings appear relatively safe, their designers say.

Yu-Chin Li and Jaime Grunlan of Texas A&M University in College Station described their team’s new technologies August 31 at the American Chemical Society national meeting in Denver.

Because fabric fibers are so thin, “being able to fire-retard them is a big deal,” observes chemist Charles Wilkie of Marquette University in Milwaukee, a fire-retardant specialist not involved with the new work. “So I’m encouraged. The new work is impressive.”

Grunlan’s team has been seeking safer alternatives to brominated fire retardants, some of which have been banned over concerns about their potential toxic effects. The researchers’ initial prototypes consisted of alternating layers of garden variety clay and a commercial polymer. But the polymer, a synthetic chemical, did not rely on renewable, green constituents. So the engineers swapped it out for an inexpensive waste material: chitosan, a natural compound extracted from shrimp and lobster shells.

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