Regensburg 2007 – scientific programme

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SYPE: Symposium Polyelectrolytes

SYPE 3: Polyelectrolytes II

SYPE 3.1: Invited Talk

Friday, March 30, 2007, 10:30–11:00, H1

Behaviour of polyelectrolyte solutions under confinement — •Dominique Langevin¹, César Marquez², Heinig Peter³, and Dan Qu⁴ — ¹Laboratoire de Physique des Solides, Université Paris-Sud, Batiment 510, 91405 Orsay — ²Laboratoire de Physique des Solides, Université Paris-Sud, Batiment 510, 91405 Orsay — ³Laboratoire de Physique des Solides, Université Paris-Sud, Batiment 510, 91405 Orsay — ⁴Laboratoire de Physique des Solides, Université Paris-Sud, Batiment 510, 91405 Orsay

We have studied free horizontal liquid films made with semidilute polyelectrolyte solutions and stabilised by minute amounts of surfactants. A stratification phenomenon is observed during film thinning, with a step size close to the mesh size of the polymer network: dark domains nucleate and expand, the outer polymer layer dewetting a thinner film. The kinetics of dark spot expansion is not simply related to bulk viscosity and becomes slower or faster when the film thickness decreases, depending of the surface conditions (presence or absence of a mixed polyelectrolyte surfactant surface layer). Other domain shape dynamics have been analysed and related to a local viscosity in stratifying foam films.