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. Mea surements of the low frequency dielectric response of the latex at var ious (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 conc entrations were determined with a Coulter DELSA440. Good agreement bet ween the zeta-potentials derived from the two complementary measuremen ts was found using the standard model of electrokinetics and the zeta- potential from the upper branch of the mobility-zeta-potential relatio n. To our knowledge this is the first time that classical electrokinet ic behavior has been found with ''off-the-shelf' latex particles.