Fabrication and characterization of superhydrophobicity ZnO nanoparticles with two morphologies by using stearic acid

In this work, ZnO nanoparticles (NPs) with two morphologies (ZnO nanospheres and ZnO nanorods) were prepared by wet chemical method, and superhydrophobic materials were synthesized by stearic acid modification. The effects of parameters such as time, temperature and molar mass fraction of stearic acid on the superhydrophobic properties of the composites were systematically studied, and the optimal reaction conditions were determined. The microstructure, chemical composition, surface topography, and water contact angle (CA) of the two morphologies of superhydrophobic ZnO materials have been measured by x-ray diffractometer (XRD), fourier transform infrared spectrum (FT-IR), field emission scanning electron microscope (FESEM) and water CA apparatus. The results showed that the hydroxyl groups on the surface of ZnO NPs modified by stearic acid were replaced by carboxyl groups of stearic acid, and existed on the surface of ZnO NPs in the form of coordination adsorption. The hydrophobic group (–CH3) of stearic acid was grafted onto the surface of ZnO NPs, which made it superhydrophobic. By studying the SEM and water CA of two morphologies of ZnO NPs modified by stearic acid, we found that the surface of ZnO nanospheres were easier to form micro-nano rough structure than that of ZnO nanorods, which also reveals the reason why the hydrophobic property of ZnO nanospheres modified by stearic acid was better than that of ZnO nanorods.