Langmuir, Vol.26, No.11, 7819-7823, 2010
Viscosity of Polyelectrolytes Solutions in Nanofilms
We use a thin film pressure balance to probe the rheological properties of thin liquid films. These films are made from mixed aqueous solutions of surfactants and polyelectrolytes. They drain under applied pressure in a noncontinuous way due to a stratification process of the polyelectrolytes network. The stratification kinetics was studied for films stabilized by different surfactants. Using a theoretical model, it is possible to examine the effect of both the surfactant and the film thickness on the local dissipation. On one hand, it was observed that dissipation depends on the polyelectrolyte concentration only, regardless whether the surfactant is neutral or bears electric charges opposite to those of the polyelectrolyte. On the other hand, it was found that dissipation is stronger in thinner films.