THE INTERACTION BETWEEN OPPOSITELY CHARGED POLYELECTROLYTES IN THE PRESENCE OF SOLID-SURFACES

The interaction between the oppositely charged polyelectrolytes poly(dimethyldiallylammonium chloride) (PDMDAAC) and poly(maleic acid-co-alpha-methylstyrene) (P(MS-alpha-MeSty)) in the presence of inorganic fine particles such as clay, silicic acid and glass pearls has been investigated. In experiments involving only adsorption of PDMDAAC the driving forces are electrostatic attractions between the anionic particles and the polycation. The amount of adsorbed PDMDAAC necessary for changing the surface charge of the substrates from negative to positive increased with increasing specific surface area. The adsorption of PDMDAAC and P(MS-alpha-MeSty) from their mixed solutions on to the inorganic fine particles showed a synergistic effect with respect to the amount of cationic surface charge. This effect increased with the surface charge density of the solid particles. The interaction of P(MS-alpha-MeSty) with preadsorbed PDMDAAC led to a change in the polarity of the modified particles and did not show a synergistic effect. The obvious difference between the adsorption from the mixed solutions and sequential adsorption is discussed in terms of the configuration of adsorbed polyelectrolyte complex particles formed in the solution or at the solid/liquid interface.