Fabrication of hierarchical structures with ZnO nanowires on micropillars by UV soft imprinting and hydrothermal growth for a controlled morphology and wettability

Hierarchical structures of ZnO nanowires (NWs) with different lengths on well-defined micropillars are fabricated by UV soft imprinting and hydrothermal growth. X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscope (XPS) are employed to characterize the crystal structure, morphology and chemical composition of the hierarchical structures of ZnO nanowires on micropillars. By varying the growth time, ZnO NWs of different lengths and morphology were obtained, showing distinct wettability which can be further modified by surface coating with octadecyltrichlorosilane (OTS). Our results show that under optimal growth conditions, the water contact angle (CA) and contact angle hysteresis (CAH) of the fabricated hierarchical structures after OTS surface treatment can reach 159 ± 1° and 6°, respectively.