Research Summary

The combination of surface chemistry and roughness on the micron and nanoscale imbues enhanced repellency to many natural surfaces when in contact with a high surface tension liquid such as water (surface tension γlv = 72.1 mN/m). This understanding has led to the creation of a number of biomimetic superhydrophobic surfaces (with equilibrium water contact angles greater than 150° and low contact angle hysteresis). However, researchers so far have been unsuccessful in producing super-oleophobic surfaces for liquids with much lower surface tensions; for example alkanes such as decane (γlv = 23.8 mN/m) or octane (γlv = 21.6 mN/m). Previous theoretical calculations suggest that creating such a surface would be impossible as it would require a lower surface energy than any surface created thus far. In this work, we explain how a third factor, surface curvature (in conjunction with surface chemistry and roughness), can be used to significantly enhance liquid repellency, and thus create the first ever truly superoleophobic surfaces (exhibiting low hysteresis and contact angles with decane and octane greater than 160°).