Regensburg 2007 – scientific programme

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SYPE: Symposium Polyelectrolytes

SYPE 2: Polyelectrolytes I

SYPE 2.4: Talk

Thursday, March 29, 2007, 15:00–15:15, H37

Elasticity testing of freestanding polyelectrolyte membranes with different charge density — •Ingo Dönch, Marc Nolte, and Andreas Fery — Max-Planck-Institut für Kolloid und Grenzflächenforschung, Am Mühlenberg 1, 14424 Potsdam

To build micro scale applications like a sensor or pressure sensitive valve new ways have to enter. It looks realistic to scale sensors down by using known polyelectrolyte membranes. After finding a new way to transfer polyelectrolyte multilayer films stress free to a patterned substrate, it is possible to test different properties of PE-membranes in variable environment, for changing radii. With the existing knowledge of PE-membranes, it is possible to scale down sensors for such applications. The work is primarily specializing in investigating the micromechanical response of the PE-membranes made from PDADMAC/PSS, in these we use PDADMAC with different charge density. The behavior of the resulting membrane patches is dependent only on the thickness of the membrane and the radius of the covered hole. It can be described with simple continuum mechanical models. We generate an osmotic pressure between bulk and the cavities which lead to a bending of the freestanding part of the membrane. This compliance of a fluorescent labeled film can be measured with a confocal microscope. Since the thickness of the multilayer can be precisely controlled in the nanometer range, the compliance of the membrane can also be varied over orders of magnitude. The PE-membranes are also semi-permeable, which makes them sensitive to osmotic pressure differences. Thus they are promising components for future micro-scale membrane sensors.