Dresden 2009 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 36: Microfluidics III: Soft Objects in Flow

CPP 36.1: Topical Talk

Thursday, March 26, 2009, 15:45–16:15, ZEU 160

Modifying Single Particle Diffusion by Chemical Surface Patterning — Martin Pumpa and •Frank Cichos — Molecular Nanophotonics Group, University Leipzig

Molecular dynamics at solid/liquid interfaces is among other effects defined by the strength of the interaction of the liquid with the solid surface. The hydrodynamic boundary conditions define the hydrodynamic friction a particle or molecule experiences close to this interface. Thus control of the surface properties of a solid substrate provides a route to control the interfacial molecular dynamics in liquid films. Within this contribution, we present first experimental results on a controlled manipulation of single molecule diffusion by chemically patterning glass surfaces. Using micro-contact printing, we prepare a hydrophilic/hydrophobic pattern on the surface. Typical dimensions of the structure of this pattern are on the order of a few micrometers. These surfaces are mounted in a surface forces apparatus, where the liquid covering the pattern is confined down to a film thickness of a few 100 nanometers. To study molecular dynamics, we employ single molecule tracking of labeled colloids dispersed in the liquid. A new correlation analysis of particle mobility and particle position reveals a clear spatial correlation between chemical surface preparation and particle diffusion.