Collaborative work by Professor Markus Buehler and postdoctoral associate Seunghwa Ryu and researchers at Duke University demonstrates the use of mechanical instabilities in graphene to reversibly control its surface properties. The researchers showed that substances like water droplets have a distinct way of interacting with graphene’s surface by applying mechanical strain to the system, which in turn changes the nanoscale structure of the graphene film. Harnessing a nanoscale crumpling (or buckling) instability in graphene allowed the researchers to make the graphene’s surface at the macroscale highly water repellent, creating a reversible “Lotus effect” that causes a water droplet to form a spherical shape and roll along the surface. Buehler and Ryu, now an assistant professor at Korea Advanced Institute of Science and Technology, worked on simulations and theory and the Duke researchers ran the lab experiments. Applications for this type of mechanical instability in graphene include superhydrophobic and on-demand self-cleaning surfaces, as well as electrodes that make use of graphene’s electronic properties. The work was published online Jan. 20 in Nature Materials.