Highly Charged Cationic Polyelectrolytes on Mica: Influence of Polyelectrolyte Concentration on Surface Forces

✍ Scribed by Mats A.G. Dahlgren; Per M. Claesson; Roland Audebert

• Publisher: Elsevier Science
• Year: 1994
• Tongue: English
• Weight: 401 KB
• Volume: 166
• Category: Article
• ISSN: 0021-9797
• DOI: 10.1006/jcis.1994.1304

✦ Synopsis

The surface force apparatus was used to study the effects of polyelectrolyte concentration on the interaction between mica sheets immersed in aqueous polyelectrolyte solution. We have found that at low polyelectrolyte concentration, adsorption of cationic polyelectrolyte onto negatively charged mica leads to extremely flat adsorbed layers in solution of low ionic strength. There is a repulsion between the surfaces at separations between about 100 and (10 \mathrm{~nm}). This force is of electrostatic origin when the polyelectrolyte concentration is lower than that needed to neutralize the surface charge. When increasing the polyelectrolyte concentration above the charge neutralization point, cnp, only a slight additional adsorption takes place in low-ionicstrength solution. In these systems, a steric component in the interaction force appears. The adsorption at the cnp is approximately (20 %) below that at the plateau level in the adsorption isotherm, which is found by ESCA measurements. ๑1994 Academic Press, Inc.