A computational model relating the self-assembly in a fluid of lath like particles with its rheology and gelation

TL;DR

This paper presents a Brownian dynamics model of colloidal lath particles that self-assemble into whiskers, leading to gelation, and explores how this process relates to the material's rheology.

Contribution

The study introduces a simplified computational model capturing self-assembly and gelation in lath-like particles, demonstrating gel transition without whisker branching.

Findings

Gel transition occurs in the model without whisker branching.

The model successfully simulates large timescales for rheology testing.

Whisker formation and gelation are characterized in the simulations.

Abstract

We study the self-assembly leading to a gel transition occurring in a numerical model of a solution of slender, colloidal sized particles, called laths, who interact mostly in the direction perpendicular to their areas. At the particle level, the attraction causes them to align into long aggregates of several particles, called whiskers in the literature. To simulate the process, we have developed a Brownian dynamics model in which the attractive interaction comes from a potential energy that depends on both the relative orientation of the laths as well as normal vectors to their areas, disregarding their width. The simplicity of the model allows the simulation to reach large enough times, of the order of minutes, needed to simulate numerical rheology tests. With this we are able to characterize the whisker formation, as well as to simulate the gel transition. A a conclusion of this work, we have shown that the gel transition can occur even if the whiskers are not allowed to branch, as is the case in this model.