Pressure Driven Flow of Polymer Solutions in Nanoscale Slit Pores

TL;DR

This study uses dissipative particle dynamics to analyze how polymer molecular weight, concentration, and flow rate affect flow profiles, polymer conformation, and distribution in nanoscale slit pores, revealing complex migration behaviors.

Contribution

It provides detailed insights into polymer behavior in nanoscale flows, highlighting the effects of molecular weight and concentration on flow and conformation profiles.

Findings

Mean fluid velocity decreases with higher polymer molecular weight and concentration.

Polymer conformations are highly anisotropic and non-uniform across the channel.

Polymer chains migrate towards or away from walls depending on their length.

Abstract

Polymer solutions subject to pressure driven flow and in nanoscale slit pores are systematically investigated using the dissipative particle dynamics approach. We investigated the effect of molecular weight, polymer concentration and flow rate on the profiles across the channel of the fluid and polymer velocities, polymers density, and the three components of the polymers radius of gyration. We found that the mean streaming fluid velocity decreases as the polymer molecular weight or/and polymer concentration is increased, and that the deviation of the velocity profile from the parabolic profile is accentuated with increase in polymer molecular weight or concentration. We also found that the distribution of polymers conformation is highly anisotropic and non-uniform across the channel. The polymer density profile is also found to be non-uniform, exhibiting a local minimum in the center-plane followed by two symmetric peaks. We found a migration of the polymer chains either from or towards the walls. For relatively long chains, as compared to the thickness of the slit, a migration towards the walls is observed. However, for relatively short chains, a migration away from the walls is observed.