Fig. 6.

Omniphobicity of microhoodoo arrays. (A) The apparent advancing and receding contact angles on a silanized microhoodoo surface. The inset shows droplets of heptane (red), methanol (green), and water (blue) on the microhoodoo surface. (B) A series of images obtained using a high-speed digital video camera that illustrates the bouncing of a droplet of hexadecane on a silanized microhoodoo surface. (C) A series of images (obtained over a period of 5 min), showing the evaporation of a droplet of methanol under ambient conditions, on a microhoodoo surface. (Scale bar, 1 mm). (D) A master curve showing the measured (filled symbols; denoted −M in the legend) breakthrough pressures for a number of microhoodoo and electrospun surfaces with various alkanes and alcohols, scaled with the breakthrough pressure of octane on the electrospun beads-only surface containing 44.4 wt% POSS, as a function of the robustness factor A*. Our predictions (hollow symbols; denoted −P in the legend) for the breakthrough pressures are also shown.