COLL 406 |
| Ivana B. Petkanchin, Institute of Physical Chemistry, Institute of Physical Chemistry, Bulgarian Academy of Sciences, Acad. G. Bontchev str., bl. 11, Sofia 1113, Bulgaria |
| Important information on the dynamics of counterions, i.e. the relaxation time of electric polarizability, could be obtained from electric light scattering studied in the frequency domain. The electro-optical results obtained for various particles (ferric oxide, SiO2, mica, g-Al2O3), when neutral polymers or polyelectrolytes are adsorbed on them, are reviewed. The presence of an adsorbed neutral polymer layer leads to a decrease of polarizability relaxation time (tg). In contrast, the adsorption of charged polymers gives rise to an increase of that time, irrespective of the substrate and polyelectrolyte charge. In the case of neutral polymer adsorption conformational changes could be supposed to cause the changes in counterion dynamics. When polyelectrolytes are adsorbed, the observed increase of tg is explicable with reduced counterion mobility because of their binding (“condensation”) on the adsorbed polymer. |
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Colloidal and Molecular Electro-Optics
Division of Colloid and Surface Chemistry |