A study of the electrophoretic mobility of complex colloidal systems is proposed. Two model systems will be considered: The first consists of single, nonspherical particles having a nonuniform charge density that leads to a distribution of zeta potential (for example, clay particles); and secondly, aggregates of differently charged spherical particles, (a dumbbell of two particles and chains of three or more particles). Experiments will be performed in a specially designed electrophoresis chamber mounted under a fluorescence microscope. While a theory exists for nonuniformly charged spheroids, it does not account for polarization of the double layer, which occurs at high zeta potentials. It is, thus, proposed to extend the theory to account for polarization effects. There is presently no model for the motion of linear chains of alternately charged particles. Part of this research will therefore, involve development of such a model for the case where the Debye screening length of the solution is very small relative to the diameter of the particles comprising the chain.
