Tailoring the wetting behavior of zinc oxide films by using alkylsilane self-assembled monolayers

Zinc oxide (ZnO) films with well-controlled morphologies have been prepared by electrochemical deposition. The different morphologies investigated are (i) flat and compact films, (ii) arrays of hexagonal nanocolumns, (iii) mesoporous films with open pores, and (iv) mesoporous films with pores filled with a surfactant (sodium dodecyl sulfate). Increasing the volume of voids in the film or the roughness gives rise to a dramatic increase in the layer wettability. The presence of surfactant in the film and/or the post-deposition binding of an alkylsilane (octadecylsilane) yield hydrophobic surfaces with contact angles measured as high as 145∘ after an optimized silane adsorption process.