A superoleophobic surface with anisotropic flow of hexadecane droplets

In this paper, a grooved mushroom structured surface, with superoleophobicity and anisotropic flow of hexadecane with a low surface tension is reported. The grooved mushroom structure was fabricated using a simple and cost-effective wet etching process on Si wafer. The wetting properties of the fabricated surface were studied through static contact angle (CA), contact angle hysteresis (CAH), and tilted angle measurements in the parallel and orthogonal directions. The maximum static CA of hexadecane droplets was 159° in the parallel direction and 142° in the orthogonal direction, respectively. The results from the CAH measurements indicated that the wetting and flow on the grooved mushroom structure were anisotropic. Furthermore, it was verified experimentally that the ridge height and distance between the top layers were key to determining the oleophobicity and anisotropic flow.