22 March 2007

Getting Physical With Molecules

by Kate Melville

The same researchers at the University of Illinois at Urbana-Champaign (UI) who came up with self-healing plastic have described in Nature a new technique that utilizes mechanical force to alter the course of chemical reactions.

"This is a fundamentally new way of doing chemistry," said UI's Jeffrey Moore, explaining how mechanical energy allows chemists to "go into molecules" and pull on specific bonds to drive desired reactions.

Demonstrating the technique, Moore and colleagues placed a mechanically active molecule - dubbed a mechanophore - at the center of a long polymer chain. The polymer chain was then stretched in opposite directions by a flow field created with cavitating bubbles, subjecting the mechanophore to a mechanical tug of war.

"We created a situation where a chemical reaction could go down one of two pathways," Moore said. "By applying force to the mechanophore, we could bias which of those pathways the reaction chose to follow."

"We have demonstrated that it is now possible to use mechanical force to steer chemical reactions along pathways that are unattainable by conventional means," Moore said. "We look forward to developing additional mechanophores whose chemical reactivity will be activated by external force."

Source: University of Illinois at Urbana-Champaign