INTERACTION OF COLLOIDAL DISPERSIONS OF NONSTOICHIOMETRIC POLYELECTROLYTE COMPLEXES AND SILICA PARTICLES

Stable non-stoichiometric polyelectrolyte complex dispersions (PEG) wi th cationic excess charges were used to study the efficiency of charge modification of silica particles. The complex dispersions formed by t he interactions of poly(diallyldimethyl-ammonium chloride) (PDADMAC) o r polyethylenimine (PEI) with poly(maleic acid-co-alpha-methylstyrene) are stable but differ in their cationic net charge. It can be seen fr om the results that the amount of preformed complex dispersion necessa ry for complete adsorption and for discharging the negative surface of the substrates tested is quite different for the PDADMAC complex and the PEI complex. Depending on the molecular weight and the type of fun ctional groups of PDADMAC and PEI, polyelectrolyte complex particles t hat differ in their conformation, diameter and charge accessibility ar e formed. In the case of glass pearls, a substrate with a very high su rface charge density, we can demonstrate that the effectiveness of cha rge modification with the PDADMAC complex is higher than with the PEI complex. Accordingly, the results suggest that the steric differences between the polyelectrolyte complexes tested is less significant for s ilicic acid, a substrate with a large specific surface.