Investigations Into Superhydrophobicity of a Soot Surface Attributed to Nano-Asperities

Abstract

Superhydrophobicity in nature is the result of multiscale (hierarchical) roughness which consists of nano-asperities superimposed on micrometer scale roughness. A low-cost superhydrophobic surface was prepared by depositing soot on Vaseline coated glass substrates. The surface was rapidly prepared without any sophisticated fabrication facilities. The surface exhibited a remarkably high water contact angle of 161 deg and a roll-off angle of 3 deg. Atomic force microscopy (AFM) of the surface was done which revealed a very rough surface. The roughness features with nano-asperities superimposed on micrometer scale roughness enhance the water repellency. The micrometer scale peaks on the surface support the water droplet in a Cassie–Baxter state with the nano-asperities sheltering a composite interface below the droplet. The work of adhesion for the surface was also low at 18 nJ. The study will enable easy preparation of a cost effective superhydrophobic surface.