Surface electrical properties of polystyrene latex - 2. ESA and dielectricresponse

A polystyrene latex suspended in HCl has been studied by dielectric respons e and dynamic mobility measurements. The aim was to sec if these data, alon g with previous results from other techniques, could be interpreted in a co nsistent way within the standard electrokinetic model to yield information about the surface electrical properties of the latex. It was found that the zeta-potentials deduced from dynamic mobility and conductivity measurement s were reasonably consistent, but did not agree well with those deduced fro m the electrophoretic mobility. The use of a dynamic Stern layer did not im prove the agreement to any great extent. It is conjectured that differences in the methods of preparation, in particular the use of centrifugation, ma y be responsible for some of the disagreement. The pH-dependence of the dyn amic mobility was also investigated and found to be weak. The dielectric re sponse measurements showed significant discrepancies from the predictions o f the standard electrokinetic model in the kHz regime, and the dynamic Ster n layer model with realistic parameters could not improve the agreement ver y much, However the experimental relaxation frequencies were in good agreem ent with the predictions of the theory. (C) 1999 Academic Press.