Dynamics and stability of dispersions of polyelectrolyte-filled multilayer microcapsules

TL;DR

This study investigates the dynamic behavior, charge properties, and aggregation tendencies of polyelectrolyte-filled microcapsules, revealing semi-permeability, charge acquisition, and interaction potentials influencing their stability in dispersion.

Contribution

It provides new insights into the charge dynamics, permeability, and interaction potentials of polyelectrolyte microcapsules, which were not previously characterized in detail.

Findings

Microcapsules acquire charge from encapsulated polyions.

The diffusion behavior resembles that of charged solid particles.

Aggregation occurs faster than sedimentation or surface adhesion.

Abstract

We report dynamic and coagulation properties of a dispersion of polyelectrolyte multilayer microcapsules filled with solutions of a strong polyelectrolyte. The capsule self-diffusion coefficient in the vicinity of the wall is measured using a particle tracking procedure from confocal images of the dispersion. Our results suggest that the microcapsules take a charge of encapsulated polyions, which indicates a semi-permeability of the shell and a leakage of counter-ions. The diffusion of capsules in the force field is qualitatively similar to that of charged solid particles: The effective interaction potential contains a weak local attractive minimum and an electrostatic barrier. We also found that the aggregation of suspended capsules occurs faster than their sedimentation and adhesion onto a glass surface.