Polymerization With An Electrifying Jolt

Polystyrene is one of the plastics produced by atom transfer radical polymerization
Polystyrene is one of the plastics produced by atom transfer radical polymerization

Scientists have figured out how to take electricity from a battery to drive a reaction that’s widely used to make industrial plastics. The environmentally friendly method, reported in the April 1 issue of Science, gives scientists exquisite control over the process to make even more complex and specialized plastics.

The reaction, atom transfer radical polymerization (ATRP), was developed by Carnegie Mellon University (CMU) chemist Krzysztof Matyjaszewski in 1995. ATRP allows scientists to easily make polymers by putting together the polymeric building blocks in a controlled piece-by-piece fashion, much like the way Lego blocks are used to make structures. The method lets scientists create a variety of polymers with very specific, tailored properties. ATRP has been used to develop cosmetics, adhesives and drug delivery systems.

In the latest work, the researchers used a computer-controlled battery to apply an electrochemical potential across the ATRP reaction. They are calling the modified reaction electrochemically mediated ATRP (eATRP). By tweaking the current and voltage, the researchers were able to manipulate the reaction as they saw fit, giving them a great deal more flexibility in how they make polymers.

CMU’s director of media relations, Jocelyn Duffy, quotes Matyjaszewski in a press release:

“This marks the first time that we’ve paired electrochemistry with ATRP, and the results were startlingly successful,” said Matyjaszewski, the J.C. Warner Professor of Natural Sciences at CMU. “We found that by adjusting the current and voltage we could slow and speed up, or even start and stop the reaction on-demand.  This gives us a great deal more flexibility in conducting our reactions that should lead to the development of precisely engineered materials.”

In regular ATRP reactions, scientists use a copper catalyst but sometimes, the level of copper needed to keep the reaction going would be toxic. In the current study, Matyjaszewski, Andrew Magenau, and colleagues looked to electricity to keep ATRP running and reduce the reliance on copper.

The result? Besides giving scientists finer control over polymer design, eATRP is more environmentally friendly than ATRP.

Science correspondent Mike Brown explains in his Chemistry World article,

Matyjaszewski hopes that the simplicity of the method will mean it can be scaled up for industrial use. “It is versatile, so we plan to use different metal complexes, not just copper, such as iron, which is less toxic generally,” he says. “We also hope to use this method to grow polymers from proteins and enzymes as well.”

Source: “Electrifying polymers,” Chemistry World, 03/31/11
Source: “Polymer Synthesis On Command,” Chemical & Engineering News, 03/31/11
Source: “Carnegie Mellon Researchers Electrify Polymerization,” Carnegie Mellon University press release, 03/31/11
Source: “Electrochemically Mediated Atom Transfer Radical Polymerization,” Science, 04/01/11
Image by Crispin Semmens/conskeptical, used under its Creative Commons license.

Rajendrani "Raj" Mukhopadhyay is a science writer and editor who contributes news stories and feature articles on scientific advances to a variety of magazines. Raj holds Ph.D. in biophysics from Johns Hopkins University.

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