Fabrication of superhydrophobic surface of hierarchical ZnO thin films by using stearic acid

Flower-like hierarchical ZnO microspheres were successfully synthesized by a simple, template-free, and low-temperature aqueous solution route. The morphology and microstructure of the ZnO microspheres were examined by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The bionic films with hydrophobicity were fabricated by the hierarchical ZnO microspheres modified by stearic acid. It was found that the hydrophobicity of the thin films was very sensitive to the added amount of stearic acid. The thin films modified with 8% stearic acid took on strong superhydrophobicity with a water contact angle (CA) almost to be 178° and weak adhersion. The remarkable superhydrophobicity could be attributed to the synergistic effect of micro/nano hierarchical structure of ZnO and low surface energy of stearic acid.

► ZnO hierarchical microspheres are synthesized.
► The bionic films with hydrophobicity are fabricated from the ZnO hierarchical microspheres modified by stearic acid.
► The hydrophobicity of the thin films is very sensitive to the added amount of stearic acid.
► The thin films modified with 8% stearic acid took on strong superhydrophobicity and weak adhersion.
► The superhydrophobicity attributes to surface roughness and the modification of stearic acid.