Restructuring of small flocs of polystyrene latex with polyelectrolyte

The structure of small flocs formed of negatively charged polystyrene latex particles with cationic polyelectrolyte was investigated to clarify the characteristics of the restructuring process of colloidal flocs. Experiments were designed in order to elucidate the effect of the different kinetical patterns in the adsorption of polyelectrolytes at the surface of colloidal particles on the restructuring process of flocs. In the experiments, flocs were formed in a standard mixing apparatus and their morphology was monitored by using a microscope. The relation between the maximum distance in the projection of a formed floc and the number of primary particles comprising the floc was used as the evaluation index of the floc structure. It was found that the restructuring of flocs takes place facilely under the condition of high ionic strength. On the other hand, under the condition of low ionic strength, the degree of restructuring varied with the molecular weight. Flocs with bulky structure were formed when polyelectrolytes with high molecular weight were used. This result of the restructuring of floc as functions of the ionic strength of solution and the molecular weight of polyelectrolyte is consistent with the rearrangement behavior of adsorbing polyelectrolytes reported previously [K. Aoki, Y. Adachi, J. Colloid Interface Sci. 300 (2006) 69–77].