Synthesis and characterization of cationized latexes in dilute suspensions

The cationization of polystyrene lattices with the emulsifiers dodecylbenzyldimethylammoniumchloride (LDB) and hexadecylvinylbenzyldimethylammoniumchloride (CVDAC) has been investigated. The synthesized lattices were characterized by measuring the size, the surface charge density and the electrophoretic mobility in dilute suspensions. The surface charge was investigated further by recording the stability of the latex against mono-, di- and trivalent anions and cations. The dependence of the ζ-potential on the ions is discussed with reference to the Schulze-Hardy rule and the Hofmeister (lyotropic) series. It was found, as expected, that the properties could be explained primarily by the valency of the charge of the counterions, but that the interaction of the latex with the cocations also plays a significant role. Comparing the results of the potentiometric titration and the electrophoretic mobility it was found that the emulsifier in excess of charge neutralization seems to be largely removed during the rigorous washing and ion exchange sequences prior to the surface charge titrations.