Regensburg 2004 – scientific programme

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CPP: Chemische Physik und Polymerphysik

CPP 15: POSTER: Polymers and Biomaterials

CPP 15.37: Poster

Tuesday, March 9, 2004, 17:00–19:00, B

Slippage and Nanorheology of Thin Polymer Films — •Renate Konrad and Karin Jacobs — Experimental Physics, Saarland University, POB 151 150, 66041 Saarbrücken

The properties of a liquid in contact with a solid interface are very important for applications involving e.g. flow through porous media or in lab-on-a-chip devices. Solving the hydrodynamic equations for a liquid flowing over a solid surface, one usually assumes the relative velocity between liquid and solid to be zero, which is the so-called No-dqno-slip boundary conditionNo-dq. Experiments with complex fluids and, very recently, also with simple (Newtonian) fluids have shown that there can be a non-zero velocity (No-dqslippageNo-dq) at the boundary. The sizes involved are expected to be on the nm-scale. On the same scale we therefore determine the velocity and the shape of a moving liquid front. Both are known to serve as extremely sensitive No-dqnano-rheometersNo-dq. It is expected from theory that slippage is enforced for smooth and low surface-energy substrates. In our experiments, we vary the substrate properties as well as the ones of the liquid like viscosity and viscoelasticity. A significant correlation between these system properties and the sliding friction can be found.