Simulating Tethered Polymer Layers in Shear Flow with the Dissipative Particle Dynamics Technique

Abstract

The dissipative particle dynamics (DPD) method is used to simulate shear flow between two flat plates. To test this technique, simulations were conducted of both constant and oscillatory shear of a simple fluid. The results of these simulations agree well with theoretical predictions. We subsequently applied our model to study the effect of shear flow on end-tethered polymer layers ("brushes"). When exposed to a constant shear flow, chains in a polymer brush are stretched in the direction of the flow, and the overall layer thickness decreases. This result is similar to what was found in previous simulation studies. However, in the present simulations solvent particles are taken into account explicitly. At low frequencies, the response of a brush to oscillatory shear is qualitatively similar to its response to constant shear. As the flow velocity changes during an oscillation cycle, the polymer chains are able to relax their configurations with respect to the shear rate. At higher frequencies the interpretation of the brush behavior becomes more difficult due to conflicting time scales of the polymer and solvent dynamics in the present DPD model.

Dissipative Particle Dynamics (DPD): An Overview and Recent Developments

“…For example, Wijmans and Smit used DPD to simulate shear flow between two flat plates and to study the effects of shear flow on end-tethered polymer layers ("brushes") [129]. They found that as the flow velocity changes during an oscillation cycle, the polymer chains are able to relax their configurations with respect to the shear rate.…”

Dissipative Particle Dynamics Simulations of Polymer Brushes: Comparison with Molecular Dynamics Simulations

“…[28,29] The DPD technique was also applied to simulate polymer brushes under shear. [41,42] Recently, the interface between a brush and a melt under shear was investigated by MD simulations using a DPD thermostat. [43] In this paper, we compare DPD simulation results with previous MD results and SCF predictions to investigate monomer density and chain stretching.…”

Multicompartment Micelles From π‐Shaped ABC Block Copolymers

“…It can be used to study systems over larger length and time scales than classical molecular dynamics and Monte Carlo simulations which have been successfully used to study microstructures and properties of polymers in bulk state and in solvent. [23][24][25][26][27][28][29][30][31] In this method a series of soft particles are considered interacting with each other and each particle represents a small volume of fluid containing many atoms. A modified velocity-Verlet algorithm was used here to integrate the Newton's equations of motion: …”