When asked to think of a chemical reaction, you might picture bubbling liquids in a beaker, or maybe applying heat to a mixture until something transforms. But some of the most important reactions in nature and industry don’t need heat or solvents. Instead, they need force.
Mechanochemistry is where physical pressure or stress triggers chemical reactions. Imagine molecules being rammed together like bumper cars, or shaken up in a giant cocktail shaker. That shaking and colliding happens every day inside car engines, manufacturing equipment and experimental green reactors. But until recently, scientists have struggled to explain exactly how these force-fueled reactions happen or how to make them work better. At Penn Engineering, the laboratory of Robert Carpick, John Henry Towne Professor in Mechanical Engineering and Applied Mechanics (MEAM), was looking at this issue as members of the Center for the Mechanical Control of Chemistry, a National Science Foundation-funded Chemical Center of Innovation that aims to transform the understanding and adoption of mechanochemistry.
Now, Carpick, along with Cangyu Qu, postdoctoral researcher, and Lu Fang, a former Ph.D. student in the Carpick lab, has developed a theoretical model that overcomes previous challenges in accurately describing the relationship between mechanical stress and chemical reactions. Their recent study, published in APS’ Physical Review B, fills in the gap for describing the forces that occur when molecules are squeezed between two surfaces. This result helps make it easier to predict mechanochemical reactions, which are promising for the green manufacturing of plastics, metallic compounds, lubricants and more.
