May 13 (Fri) 2011, 1:30 pm
Prof. Roman Boulatov (Chemistry, University of Illinois at Urbana-Champaign)

“The force behind mechanochemistry”

Place: Rm 310, Chemistry Bldg.

All are cordially invited to attend the talk.

Abstract

Diverse chemical processes in biology and materials science are accelerated by spatial energy gradients that span tens to hundreds of nanometers. Some call such phenomena mechanochemistry, chemomechanics or force-induced chemistry because energy gradients and force have the same units (Newtons). Yet force does not appear as a variable in modern models of chemical kinetics. The reason is that the vast majority of reactions studied and used by chemists occur in molecules too small to be affected by the energy gradients accessible in condensed media. In contrast, polymers are sufficiently long to stretch into metastable conformations or even break when exposed to energy gradients such as those in elongational fluid flows or in bulk materials under macroscopic loads. We want to understand the existing “mechanochemical” phenomena and to create new reactions, materials and devices that exploit mesoscopic energy gradients to drive useful chemistry and to increase the efficiency of extracting useful work from chemical fuels. To do so we need to be able to predict force-dependent kinetics of diverse reactions as easily and accurately as we now predict rates as a function of temperature, pressure or solvent polarity. Such predictive capabilities require a general non-empirical integration of energy gradients (force) as an explicit variable into the modern kinetic theories. I will describe the contributions of my group to developing the theory of chemical kinetics in energy gradients, the experimental and computational tools we have created to test this theory and the counterintuitive results about the relationships between force and reaction rates that these tools revealed.