Turning a surface superrepellent even to completely wetting liquids

Superhydrophobic and superoleophobic surfaces have so far been made by roughening a hydrophobic material. However, no surfaces were able to repel extremely-low-energy liquids such as fluorinated solvents, which completely wet even the most hydrophobic material. We show how roughness alone, if made of a specific doubly reentrant structure that enables very low liquid-solid contact fraction, can render the surface of any material superrepellent. Starting from a completely wettable material (silica), we micro- and nanostructure its surface to make it superomniphobic and bounce off all available liquids, including perfluorohexane. The same superomniphobicity is further confirmed with identical surfaces of a metal and a polymer. Free of any hydrophobic coating, the superomniphobic silica surface also withstands temperatures over 1000°C and resists biofouling. Surface roughness alone can make a material superrepellent to almost any liquid. Undercutting the surface keeps liquids at bay The shape of an umbrella is designed both to protect the holder from falling droplets and to have the collected rainwater flow away from the person underneath. Liu and Kim exploited the idea of an umbrella to make materials with a surface that repels almost any liquid. Science, this issue p. 1096