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CPP: Chemische Physik und Polymerphysik
CPP 11: Colloids and Nanoparticles I
CPP 11.1: Talk
Monday, March 8, 2004, 14:00–14:15, H 39
Ordering of soft and hard colloidal particles confined in thin liquid films — •Regine v. Klitzing, Tatjana Mauser, and Branko Kolaric — Stranski-Laboratorium, TU Berlin, Strasse d. 17. Juni 112, 10623 Berlin
Small angle neutron scattering experiments at solutions containing branched polyelectrolytes or Silica particles show a structure peak which indicates interactions between the colloids. The position of the structure peak qmax scales with the concentration c as qmax ∝ c1/3 for the colloidal dispersions which is predicted by theoretical models. In order to investigate the effect of geometrical confinement the solutions are confined in a free-standing surfactant film. The sum of interactions between the film surfaces is determined quantitatively by the disjoining pressure (disjoining pressure in dependence vs. film thickness) and it is measured by varying the outer pressure in a so–called thin film pressure balance. For both systems the film drains stepwise with increasing pressure due to oscillatory structural forces. In polyelectrolyte films the step size depends on the polyelectrolyte concentration and corresponds to the correlation length in solution. In contrast to this, the step size in films containing (hard) Silica particles is constant irrespective the particle concentration.