Zeta Potential and Slip Coefficient Measurements of Hydrophobic Polymer Surfaces Exploiting a Microchannel

Abstract

The surface charge and wettability of polymer surfaces are important properties that affect various physicochemical properties such as adhesion, hydrophilicity, and swelling. The zeta potential gives information of the ions distribution at the electric double layer (EDL), and the Navier slip coefficient is also an important indicator of the wettability of surfaces. In the present investigation, a technique is devised to measure the zeta potential and the slip coefficient of polymer surfaces nondestructively exploiting electrokinetic flows in a microchannel, which is formed by combining a probe cell and a macroscopic polymer surface under consideration. By measuring zeta potential and volumetric flow rate of electroosmotic flow at various bulk ionic concentration, one can estimate the zeta potential and slip coefficient accurately even under significant experimental errors in the measurement of streaming potential and volumetric flow rate. The method devised in the present investigation may be employed to estimate zeta potential and slip coefficient of various polymeric surfaces, which are important characterizing various physicochemical properties of polymers.