Adhesion-Regulated Switchable Fluid Slippage on Superhydrophobic Surfaces

Surface adhesion is regulated by sparsely grafting responsive hydrophilic polymer chains on superhydrophobic surfaces but without obviously changing the wettability. We study experimentally how adhesion of superhydrophobic surfaces affects liquid slip. The slip length of water on such surfaces decays quickly as the adhesive force increases. This intrinsic dependence is theoretically explained based on scaling descriptions for specific geometries. A slip length range of 87 mu m can be achieved reversibly by changing the temperature below and above the low critical solution temperature (LCST) of the grafted temperature-sensitive polymer. The results shed light on the intrinsic mechanism of liquid slip on textured surfaces and have important implications in the design of smart microfluidic and biofluidic devices, in which the regulation of fluid flow is highly desirable.