ROTATIONAL AND TRANSLATIONAL DIFFUSION IN SPHERICAL POLYSTYRENE MICROGEL SOLUTIONS

In solutions of spherical polystyrene microgels rotational and translational diffusion is investigated by means of nuclear magnetic resonance. By relaxation time measurements it could be shown that rotational diffusion is controlled by anisotropic segmental motions of sub-chains between crosslinks. The overall rotation of the spheres runs off more slowly and does not influence the nuclear relaxation. From self-diffusion coefficients obtained by the pulsed-field-gradient technique the conclusion can be drawn that at law concentrations the diffusion obeys Fick's law, but at higher concentrations there is a restricted ''in cage'' diffusion in a volume with a diameter of about 200 nm.