Synthetic polymers are all around us. Researchers are working on ways to more finely control the chemical process that produces these compounds, to generate polymers with, for example, specific molecular masses and architectures.

Krzysztof Matyjaszewski at Carnegie Mellon University in Pittsburgh, Pennsylvania, and his collaborators show that applying a suitable electrochemical potential to a copper catalyst commonly used in polymerization reactions switches the catalyst between a dormant (oxidized) and an active (reduced) state. Because the polymerization reaction rate depends on the ratio of the concentrations of the two copper species, this toggling provides fine control over the yield and molecular mass of the product. Moreover, polymerization can be stopped and restarted at will by adjusting the applied potential.

The approach may be extendable to various types of polymer, and might be used to generate complex architectures, the authors say.

Science 332, 81–84 (2011)