engleski

Predicting the outcomes of interpolyelectrolyte neutralization at surfaces on the basis of complexation experiments and vice versa

The study is carried out with the aim of establishing in which measure the outcomes of polyelectrolyte multilayer formation can be predicted on the basis of the results of complexation studies in solution and vice versa. For this purpose, the correlation between the process of complex and multilayer formation involving three pairs of vinylic polyions in solutions of binary 1:1 sodium salts (NaX ; X = F, Cl, Br, I, NO3, ClO4) was explored by means of dynamic and electrophoretic light scattering, potentiometry, microcalorimetry, spectrophotometry and quartz crystal microbalance. The gradual reactant mixing in solution at lower salt concentrations resulted in Fuoss-Sadek sequence of events (primary complexes → secondary complexes→1:1 flocculate)., whereby the obtained nano-complexes could be overcharged. At high salt concentration and excess polycation present, metastable nano-complexes and precipitates containing surplus of positively charged monomers were formed. The amount of extrinsically compensated charge was in accord with the polycation affinities toward counteranions, established by monitoring the electrolyte-induced aggregation of positively charged nano-complexes. Perfect analogy with respect to counteranion influence on the amount of adsorbed polycation was noticed for corresponding multilayers. Aside from providing the deeper understanding of interpolyelectrolyte neutralization, the gained insights can also be used to steer the polyelectrolyte multilayer composition and properties.

polyelectrolyte complexes ; polyelectrolyte multilayers ; ion-specific effects ; overcharging ; extrinsic charge compensation

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