Spontaneous Deicing on Cold Surfaces

Although freezing of a droplet on cold surfaces is a universal phenomenon, its mechanisms are still inadequately understood, especially on the surfaces of which the temperature lower than -60 degrees C . Here, we report the unique spontaneous deicing phenomena of a water droplet impacting on cold surfaces with a temperature as low as -120 degrees C . As a hydrophilic surface is cooled below a critically low temperature (e.g., -57 degrees C for a silicon surface with a native oxide), the impacting water droplet spontaneously delaminates from the substrate and freezes radially outward in a horizontal plane, as opposed to the typical upward freezing shown on a warmer surface. The self-delamination phenomenon is suppressed or reinstated by the combination o f thermal and hydrophobic modifications of the surface, which can be taken advantage of for effective deicing schemes for icephobic surface applications.