UC Irvine

We have experimentally measured flow rates of water through hydrophilic and hydrophobic single pipes with diameters ranging from 10 $\mu$m to 200 nm. We developed a method of coating the pipes with a hydrophobic polymer roughly 2 nm thick and verified the hydrophobic nature of the pipes after treatment. The exact diameters of the tubes were measured using a gaseous flow impedance test or imaged directly via scanning electron microscopy. The flow rates through both the hydrophobic and hydrophilic pipes agree with theory for viscous Poiseuille flow and are effectively indistinguishable from each other.