  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.
