Energy Squeezed Out Of Polymers | Chemical & Engineering News
Volume 90 Issue 11 | p. 53 | Concentrates
Issue Date: March 12, 2012

Energy Squeezed Out Of Polymers

Mechanochemical action induces polymers to generate radicals that in turn produce hydrogen peroxide to drive subsequent reactions
Department: Science & Technology
News Channels: Materials SCENE
Keywords: mechanochemistry, hydrogen peroxide, polymers, energy efficiency
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WALK THIS WAY
Walking in a sneaker generates H2O2, which cleaves the boronic ester protecting group of 7-hydroxycoumarin, causing the molecule to fluoresce blue.
Credit: Grzybowski Lab
After two hours of compression from walking, the pocketed sole of a sneaker fluoresces (blue), indicating the mechanochemical generation of H2O2 and subsequent cleavage of protected 7-hydroxycoumarin that had been injected into the shoe’s bottom.
 
WALK THIS WAY
Walking in a sneaker generates H2O2, which cleaves the boronic ester protecting group of 7-hydroxycoumarin, causing the molecule to fluoresce blue.
Credit: Grzybowski Lab

Generating chemical energy to run reactions in the lab could be as easy as squeezing a spongy stress ball, according to researchers at Northwestern University. H. Tarik Baytekin, Bilge Baytekin, and Bartosz A. Grzybowski have shown that, by compressing polymers in contact with water, they can generate hydrogen peroxide to drive various reactions at a mechanical-to-chemical energy conversion efficiency of up to 30% (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201108110). By comparison, typical power plants generate energy with 30 to 40% efficiency. When polymers are compressed, some of their bonds cleave homolytically, generating radicals. If water is present at the polymer surface, H2O2 is produced when the radicals diffuse to the interface. The researchers demonstrated this mechanochemical phenomenon by injecting an aqueous solution of a nonfluorescent boronic ester of 7-hydroxycoumarin into the sole of a sneaker. After being walked on for two hours, the polymeric sole fluoresced brightly, indicating the generation of H2O2 and the compound’s subsequent cleavage of the boronic ester and release of the fluorescent 7-hydroxycoumarin. “When you look at all the polymers out there—in car tires, soles, and plastic bags—just aging unproductively, it is such a wide-open opportunity for energy retrieval,” Grzybowski says.

 
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