Modulation of Electroosmotic Flow by Neutral Polymers

Abstract

Polymer coating is widely used to modulate the fluid flow in micro- and nanometer pores and flows that are sensitive to surface properties such as electroosmotic flow. Here we report on the dissipative particle dynamics simulations of the modulation of electroosmotic flow by neutral polymers. In these coarse-grained simulations, fluid and polymers are resolved at a scale comparable to polymer size and the two-way coupling between polymer conformation and fluid flow are explicitly accounted for. The simulations indicate that, in the parameter space explored, the screening of electroosmotic flow by polymers decreases nonlinearly as the external electric field increases. Such an observation is understood by analyzing the surface coverage by polymers, height and orientation of the grafted polymers, and the two different modes of flow screening by polymer segments as a function of the external electric field. Understanding the effects and interplay of these physical processes is crucial for the rational design of polymer coating for flow control in microfluidic and nanofluidic systems.