ELECTROPHORETIC MOBILITY AND DIELECTRIC RESPONSE MEASUREMENTS ON ELECTROKINETICALLY IDEAL POLYSTYRENE LATEX-PARTICLES

We measured the dielectric response and electrophoretic mobility of a polystyrene latex to test the classical theory of electrokinetics. Measurements of the low frequency dielectric response of the latex at various (low) volume fractions were made using the four-electrode signal-processing spectrometer of Myers and Saville (J. Colloid Interface Sci. 1989, 31, 448). Electrophoretic mobilities over a range of NaCl concentrations were determined with a Coulter DELSA440. Good agreement between the zeta-potentials derived from the two complementary measurements was found using the standard model of electrokinetics and the zeta-potential from the upper branch of the mobility-zeta-potential relation. To our knowledge this is the first time that classical electrokinetic behavior has been found with ''off-the-shelf' latex particles.