The Hydrodynamic Interaction in Polymer Solutions Simulated with Dissipative Particle Dynamics

TL;DR

This study investigates how dissipative particle dynamics simulations accurately reproduce polymer solution dynamics, focusing on the effects of the Schmidt number on hydrodynamic interactions and confirming the models' applicability across different conditions.

Contribution

The paper demonstrates that typical DPD simulations correctly reproduce Zimm dynamics and hydrodynamic screening in dilute and concentrated polymer solutions, clarifying the impact of the Schmidt number.

Findings

Polymer dynamics in dilute solutions follow the Zimm model.

Reducing the Schmidt number causes deviations towards the Rouse model.

Hydrodynamic and excluded volume interactions are well reproduced at various concentrations.

Abstract

We analyzed extensively the dynamics of polymer chains in solutions simulated with dissipative particle dynamics (DPD), with a special focus on the potential influence of a low Schmidt number of a typical DPD fluid on the simulated polymer dynamics. It has been argued that a low Schmidt number in a DPD fluid can lead to underdevelopment of the hydrodynamic interaction in polymer solutions. Our analyses reveal that equilibrium polymer dynamics in dilute solution, under a typical DPD simulation conditions, obey the Zimm model very well. With a further reduction in the Schmidt number, a deviation from the Zimm model to the Rouse model is observed. This implies that the hydrodynamic interaction between monomers is reasonably developed under typical conditions of a DPD simulation. Only when the Schmidt number is further reduced, the hydrodynamic interaction within the chains becomes underdeveloped. The screening of the hydrodynamic interaction and the excluded volume interaction as the polymer volume fraction is increased are well reproduced by the DPD simulations. The use of soft interaction between polymer beads and a low Schmidt number do not produce noticeable problems for the simulated dynamics at high concentrations, except that the entanglement effect which is not captured in the simulations.