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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 58: Fluids and Interfaces II

CPP 58.2: Vortrag

Donnerstag, 23. März 2017, 10:30–10:45, ZEU 255

Structuring of micro particle assemblies at the solid liquid interface by light driven diffusioosmosis — •David Feldmann¹, Salim Maduar², Olga I. Vinogradova^2,3,4, and Svetlana Santer¹ — ¹Institute of Physics and Astronomy, University of Potsdam, 14476 Potsdam, Germany — ²A.N. Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 119071 Moscow, Russia — ³Department of Physics, M. V. Lomonosov Moscow State University, 119991 Moscow, Russia — ⁴DWI-Leibniz Institute for Interactive Materials, RWTH Aachen, 52056 Aachen, Germany

Light-induced diffusioosmotic flows can be used to manipulate and structure particle assemblies at the solid liquid interface.[1] The main player is an azobenzene containing cationic surfactant. Azobenzene switches from a trans to a cis state under UV and back under visible light or by thermal relaxation. A particle-surfactant dispersion is pipetted onto a substrate and placed under a microscope, in which two lasers (UV, green) are coupled. Surfactant adsorbs to the surface, depending on isomer and surface properties, and creates an electrical double layer(EDL). Local irradiation induces a gradient in surfactant concentration creating a diffusioosmotic flow in the EDL, which drags particles on the surface either away (UV) or to (green) the laser spot, with velocities around 1µm/s. With these flows we clean, gather, and structure particles assemblies on flat surfaces or direct particles along patterned surfaces.[1]Feldmann, D. et al. Sci. Rep. 6, 36443; doi: 10.1038/srep36443 (2016).