Parametrization of coarse grained force fields for dynamic property of ethylene glycol oligomers/water binary mixtures

TL;DR

This paper develops a coarse-grained molecular dynamics method to accurately predict the shear viscosity of ethylene glycol oligomer/water mixtures by parameterizing non-bonded interactions based on experimental self-diffusion data.

Contribution

It introduces a three-step parameterization scheme for CG force fields that effectively reproduces experimental dynamic and density data for EGO/water mixtures.

Findings

CG model accurately predicts shear viscosities

Simulation matches experimental self-diffusion coefficients

Method applicable to low molecular weight polymers

Abstract

To evaluate shear viscosity of ethylene glycol oligomers (EGO)/water binary mixture by means of coarse-grained molecular dynamics (CG-MD) simulations, we proposed the self-diffusion-coefficient-based parameterization of non-bonded interactions among CG particles. Our parameterization procedure consists of three steps: 1) determination of bonded potentials, 2) scaling for time and solvent diffusivity, and 3) optimization of Lennard-Jones parameters to reproduce experimental self-diffusion coefficient and density data. With the determined parameters and the scaling relations, we evaluated shear viscosities of aqueous solutions of EGOs with various molecular weights and concentrations. Our simulation result are in close agreement with the experimental data. The largest simulation in this article corresponds to a 1.2 microseconds atomistic simulation for 100,000 atoms. Our CG model with the parameterization scheme for CG particles may be useful to study the dynamic properties of a liquid which contains relatively low molecular weight polymers or oligomers.