Friction and Interfaces

We are all familiar with friction, as it allows us to walk, brake or hold on object without letting it slip. Often we want to have low friction, for example in verhicles to reduce energy consumption or in our joints to reduce wear of our body. However, it is very hard to predict friction as the origins are complex. Friction arises at small scales at the interface between two materials, which makes it hard to image. This lack of understanding has hampered the development of low or high friction materials from first principles, leaving it a matter of trial and error as it has been for ages. One of the first scientists to study friction was Leonardo da Vinci. He made beautiful drawings of his friction experiments as you can see on the left. He found out that friction does not depend on the macroscopic area of contact, but only on the weight applied (consider the bottom picture, the same object slid on different sides leads to the same friction force). In the Soft Matter group, we use a recently developed fluorescent molecules to image the contact area between solids with high resolution (Suhina et al., 2015). Click on the images below to learn more about our current research on friction.