Highly transparent superamphiphobic surfaces by elaborate microstructure regulation.

Superamphiphobic surfaces have attracted extensive attention from both academic and commercial communities because of their unique wettability. However, big challenge still remains as superamphiphobic surfaces frequently suffer the drawbacks of either easy adhesion of liquids with low surface tension (<27.5 mN m) or low transparency, which in turn seriously hinders their applications. Here, we report the exploitation of highly transparent superamphiphobic surfaces, which was prepared by chemical vapor deposition (CVD) of 1H,1H,2H,2H-perfluorodecyltrichlorosilane onto silica nanotubes, via elaborate microstructure regulation. The silica nanotubes are synthesized by coating multiwalled carbon nanotubes (MWCNTs) with a layer of polysiloxane followed by calcination in air. The effects of various parameters, including the concentration of MWCNTs, the solvents for re-dispersing the polysiloxane-modified MWCNTs and its spray-coating density, on superamphiphobicity and transparency were systematically studied. The results show that the superamphiphobicity and transparency are highly dependent on the solvents for re-dispersing polysiloxane-modified MWCNTs because the microstructure of the polysiloxane layer, i.e. the precursor of silica nanotubes, relies on the re-dispersing solvents. The superamphiphobic coatings feature extremely low sliding angles for various liquids with surface tension as low as 21.6 mN m and very high optical transparency, superior to most of the reported superamphiphobic surfaces, which make them promising candidates as functional surfaces or coatings for a broad variety of applications, e.g., in situ observation using microscopes, self-cleaning windows, and so on.