Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Micro and Nano Fluidics III: Lab-on-Chip Geometries

CPP 25.4: Talk

Thursday, March 29, 2007, 18:15–18:30, H37

separation of liquid mixtures on chemically patterned surfaces — •Pagra Truman, Leonid Ionov, Smrati Gupta, Petra Uhlmann, and Manfred Stamm — Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, Germany

The use of chemically patterned surfaces is an interesting tool to drive liquid flow along surfaces, micro- or nano-channels. In this work we investigate novel applications of chemically patterned surfaces namely the separation of liquid mixtures. The liquid dynamics on chemically patterned surfaces is highly complex since interfacial phenomena and flow inside the liquid influence the dynamics. As a simple model liquid mixture to study fundamental aspects of this process we apply Toluene/Water mixtures to two types of surfaces: Firstly flow on surfaces with a wetting gradient is studied. Secondly flow on surfaces with an abrupt change of wettability (hydrophilic/ hydrophobic) is investigated. Wetting gradients are prepared by binary polymer brushes made of two incompatible polymers by introducing a gradient of hydrophilicity/ hydrophobicity or surface charge via variations in the grafting density. A surface with an abrupt change of wettability is fabricated by casting an expoxy resin into the cavity of a teflon block and subsequent milling. Besides presenting experimental results the perspectives to carry out such processes in confinement for applications in microfluidics systems will be discussed.