ROTATIONAL AND TRANSLATIONAL DIFFUSION IN SPHERICAL POLYSTYRENE MICROGEL SOLUTIONS

In solutions of spherical polystyrene microgels rotational and transla tional diffusion is investigated by means of nuclear magnetic resonanc e. By relaxation time measurements it could be shown that rotational d iffusion 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-diffus ion coefficients obtained by the pulsed-field-gradient technique the c onclusion can be drawn that at law concentrations the diffusion obeys Fick's law, but at higher concentrations there is a restricted ''in ca ge'' diffusion in a volume with a diameter of about 200 nm.