Controlling water droplet motion on a surface is important for facilitating or improving the efficiency of many processes. Irrespective of the external force inducing the motion, surface wettability plays a vital role in this process. In this work, we study the effect of changing the length scale of chemical heterogeneities on wetting and droplet dynamics during the impact and condensation on surfaces with alternating, equal sized hydrophilic and hydrophobic stripes. We show that as the width of the stripes decreases to nanoscale, the surface shows near isotropic wettability. Specifically, we demonstrate that the difference between the advancing contact angle, sliding angle, and contact angle hysteresis measured parallel and perpendicular to the stripes is negligible for the nano-striped surface. Moreover, we show that the droplet dynamics during the impact and condensation on the nano-striped surfaces are similar to those observed on a chemically homogeneous surface with equivalent wettability.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)