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Stable non-stoichiometric polyelectrolyte complex dispersions (PEC) with cationic excess charges were used to study the efficiency of charge modification of silica particles. The complex dispersions formed by the interactions of poly(diallyldimethyl-ammonium chloride) (PDADMAC) or polyethylenimine (PEI) with poly(maleic acid-co-α-methylstyrene) are stable but differ in their cationic net charge. It can be seen from the results that the amount of preformed complex dispersion necessary 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 functional groups of PDADMAC and PEI, polyelectrolyte complex particles that differ in their conformation, diameter and charge accessibility are formed. In the case of glass pearls, a substrate with a very high surface charge density, we can demonstrate that the effectiveness of charge 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 silicic acid, a substrate with a large specific surface. |
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