Chemically robust superhydrophobic surfaces with a self‐replenishing nanoscale liquid coating

Abstract

Due to poor chemical robustness, superhydrophobic surfaces become susceptible to failure, especially in a highly oxidative environment. To ensure the long‐term efficacy of these surfaces, a more stable and environmentally friendly coating is required to replace the conventional salinization layers. Here, soot‐templated surfaces with re‐entrant nanostructures are precoated with polydimethylsiloxane (PDMS) brushes. An additional nanometer‐thick lubricant layer of PDMS was then applied to increase chemical stability. The surface is superhydrophobic with a nanoscale liquid coating. Since the lubricant layer is thin, ridge formation is suppressed, which leads to low drop sliding friction and fast drop shedding. By introducing a bottom “reservoir” of a free lubricant as an oil source for self‐replenishing to the upper layer, the superhydrophobic surface becomes more stable and heals spontaneously in response to alkali erosion and O₂ plasma exposure. This design also leads to a higher icing delay time and faster removal of impacting cooled water drops than for uncoated surfaces, preventing icing at low temperatures.