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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.