Colloidal suspensions of C-particles: Entanglement, percolation and microrheology

TL;DR

This study investigates the structural and dynamical properties of concentrated C-shaped colloidal suspensions, revealing entanglement, percolation transitions, and microrheological behavior through simulations and theory.

Contribution

It introduces a detailed analysis of entanglement and percolation in C-particle suspensions, including the effects of particle shape and concentration on dynamics.

Findings

Percolation transition depends on opening angle and concentration.

Dynamical decorrelation follows a stretched exponential decay.

Dragged cluster size varies with dragging direction and speed.

Abstract

We explore structural and dynamical behavior of concentrated colloidal suspensions made up by C-shape particles using Brownian dynamics computer simulations and theory. In particular, we focus on the entanglement process between nearby particles for almost closed C-shapes with a small opening angle. Depending on the opening angle and the particle concentration, there is a percolation transition for the cluster of entangled particles which shows the classical scaling characteristics. In a broad density range below the percolation threshold, we find a stretched exponential function for the dynamical decorrelation of the entanglement process. Finally, we study a set-up typical in microrheology by dragging a single tagged particle with constant speed through the suspension. We measure the cluster connected to and dragged with this tagged particle. In agreement with a phenomenological theory, the size of the dragged cluster depends on the dragging direction and increases markedly with the dragging speed.