Dynamics of a suspension of interacting yolk-shell particles

TL;DR

This study investigates the self-diffusion behavior of yolk-shell particles in a liquid, combining Brownian dynamics simulations with theoretical models to understand how internal yolks affect overall particle dynamics.

Contribution

The paper introduces a combined simulation and theoretical approach to analyze how internal yolks influence the self-diffusion of shell particles in a suspension.

Findings

Yolks do not alter static structure but affect dynamic properties.

Theoretical models accurately predict the influence of yolks on diffusion.

Simulation results agree with the effective Langevin equation approach.

Abstract

In this work we study the self-diffusion properties of a liquid of hollow spherical particles (shells)bearing a smaller solid sphere in their interior (yolks). We model this system using purely repulsive hard-body interactions between all (shell and yolk) particles, but assume the presence of a background ideal solvent such that all the particles execute free Brownian motion between collisions,characterized by short-time self-diffusion coefficients D0s for the shells and D0y for the yolks. Using a softened version of these interparticle potentials we perform Brownian dynamics simulations to determine the mean squared displacement and intermediate scattering function of the yolk-shell complex. These results can be understood in terms of a set of effective Langevin equations for the N interacting shell particles, pre-averaged over the yolks' degrees of freedom, from which an approximate self-consistent description of the simulated self-diffusion properties can be derived. Here we compare the theoretical and simulated results between them, and with the results for the same system in the absence of yolks. We find that the yolks, which have no effect on the shell-shell static structure, influence the dynamic properties in a predictable manner, fully captured by the theory.