UC Merced Researchers Explain How Mechanical Force Can Trigger Chemical Reactions

Mechanical force can do more than just push things around - it can also trigger chemical reactions. A new review by researchers at UC Merced and Penn State brings together decades of work to explain how these reactions occur and why they matter for technologies ranging from pharmaceuticals to the materials in everyday products.

The paper, published in Chemical Reviews, examines a field known as mechanochemistry, the study of how mechanical force drives chemical changes. While the concept has been around for centuries, it has seen renewed interest as a safer, greener approach to chemical synthesis. Still, scientists are working to understand exactly how mechanochemistry works.

The review highlights a key idea: When molecules are squeezed or sheared, mechanical force can distort their structure. These distortions, such as changes in bond lengths, bond angles or molecular shape, can make reactions more likely to occur.

"Mechanical force can change the geometry of molecules in ways that lower the energy needed for a reaction," said UC Merced postdoctoral researcher Sourabh Kumar, the lead author of the study. "Understanding how that happens is essential if we want to predict or control these reactions."

The researchers argue that this force-induced molecular distortion provides a unifying explanation for many mechanochemical processes. The study brings together insights from several different research approaches. Experiments can measure how reaction rates change under force. Molecular dynamics simulations can track how molecules distort as force is applied. Quantum chemistry calculations can reveal how those distortions change the energy landscape of the reaction.

By combining these approaches, scientists can begin to connect force applied at the scale of engineering systems with the chemical reactions happening at the molecular level.

The implications extend across many technologies. Researchers are exploring mechanochemical synthesis to produce pharmaceuticals, catalysts and advanced materials more efficiently while reducing waste and energy use. A better understanding of how mechanical forces activate chemical reactions could help scientists design cleaner manufacturing methods and materials.

The authors say the review also highlights major opportunities for future research. Ashlie Martini, professor of mechanical and aerospace engineering and a co-author of the paper, described mechanochemistry as "the intersection of mechanics, chemistry and materials science." Martini added that "bringing those perspectives together is what will allow us to design materials and chemical systems that respond predictably to mechanical force."