On the computational modeling of the viscosity of colloidal dispersions and its relation with basic molecular interactions

TL;DR

This paper explores how molecular interactions influence the viscosity of colloidal dispersions using dissipative particle dynamics simulations, providing educational tools for students new to soft matter research.

Contribution

It introduces a computational approach to model colloidal viscosity, linking molecular forces with macroscopic properties, and offers practical simulation code for educational purposes.

Findings

Hydrodynamic and Brownian forces significantly affect colloidal viscosity.

Dissipative particle dynamics effectively predicts surface friction and viscosity.

Educational resources are provided for studying complex fluids.

Abstract

The connection between fundamental interactions acting in molecules in a fluid and macroscopically measured properties, such as the viscosity between colloidal particles coated with polymers, is studied here. The role that hydrodynamic and Brownian forces play in colloidal dispersions is also discussed. It is argued that many body systems in which all these interactions take place can be accurately solved using computational simulation tools. One of those modern tools is the technique known as dissipative particle dynamics, which incorporates Brownian and hydrodynamic forces, as well as basic conservative interactions. A case study is reported, as an example of the applications of this technique, which consists of the prediction of the viscosity and friction between two opposing parallel surfaces covered with polymer chains, under the influence of a steady flow. This work is intended to serve as an introduction to the subject of colloidal dispersions and computer simulations, for last year undergraduate students and beginning graduate students who are interested in beginning research in soft matter systems. To that end, a computational code is included that students can use right away to study complex fluids in equilibrium.