Dynamics of Polymers Flowing through Porous Media: Interplay of Solvent Properties, Flow Rates, and Wetting

Abstract

Polymer transport in porous media controls many important industrial and technological applications. Using molecular simulations with fully coupled hydrodynamic interactions, we have previously studied the dynamics of polymers flowing through purely repulsive model porous media. The most prominent observation is the emerging of slow dynamics for the collapsed polymers at low flow rate, where the polymer transport is controlled by a globule–stretch transition at pore throats. In this work, we extend our previous work by including the wetting effect, i.e., the polymer–porous media interactions, which are ubiquitous in all realistic conditions. At high flow rate, the hydrodynamic drag forces can overcome the wetting interactions, and the polymer dynamics is like those without wetting interactions. On the other hand, at low flow rate, including polymer wetting results in rich nonmonotonic polymer transport dynamics: Weak polymer wetting in fact facilitates the polymer transport through porous media by converting 3D compact polymer globules into quasi-2D morphologies that can pass through the narrow pore throats more easily. In contrast, strong polymer wetting reduces the polymer transport especially for shorter chains, where the hydrodynamic drags are unable to pull the small polymer globules away from the porous media surfaces. To the best of our knowledge, this is the first comprehensive study showing the dynamics of polymers flowing through porous media with effects from the combinations of flow rates, solvent properties, and wetting interactions. We believe the results put forward in this study are important in understanding the fundamental nonequilibrium polymer dynamics in constraints as well as with practical implications for using polymers in subsurface applications and (bio)macromolecular separation technologies.