Regensburg 2007 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 4: Colloids and Nanoparticles II: Effective Interactions
CPP 4.6: Vortrag
Montag, 26. März 2007, 15:30–15:45, H37
A Pre-Wetting Transition on Colloidal Particles — Andreas Erbe1, Klaus Tauer2, and •Reinhard Sigel2 — 1Institute of Physics, Academia Sinica, Taiwan — 2MPI of Colloids and Interfaces, D-14476 Golm
The salt concentration around charged colloidal particles is traditionally described by the Poisson-Boltzmann equation. Not predicted by this equation is a sudden transition to a layer of high salt concentration around the colloids when the average salt concentration is enhanced. This transition has been found experimentally by ellipsometric light scattering [1]. The observation is interpreted as a first order pre-wetting transition. The interactions stabilizing the layer of enhanced concentration as well as the extent and the softness of the layer are discussed. The pre-wetting by a highly concentrated salt solution can also explain an experimental finding for charged spherical brushes composed of polyelectrolytes around colloidal particles. Here, a concentration profile similar to uncharged spherical brushes is detected, instead of the streched chain behavior predicted by theory.
[1] A. Erbe, K. Tauer, R. Sigel, Langmuir, in press.