Nano- & Microfluidics:

Nanoscale Discontinuities at the Boundary of Flowing Liquids: a Look to Structure and Dynamics

Project Leadership:	Prof. Dr. Hartmut Zabel Ruhr-Universität Bochum Lehrstuhl für Experimentalphysik IV – Festkörperphysik
	Prof. Dr. Andreas Magerl Friedrich Alexander - Universität Erlangen - Nürnberg Lehrstuhl für Kristallographie und Strukturphysik Erlangen

Summary of the project:

Usually liquids are characterized as 3D isotropic systems. However a boundary, like the free liquid surface or a solid-liquid interface, distinguishes a spatial direction and induces anisotropy. This reduced symmetry may be limited to a nanosize length scale next to the surface/interface region or it may penetrate into the liquid on a much more extended length scale. Related ordering phenomena in complex liquids are well established, and more recently it was shown that near-interface structures depend crucially on the chemical termination of the solid boundary. It is further established that shear in flowing liquids may have a pronounced influence on bulk structures, and further dramatic effects may occur like discontinuities at interfaces as evidenced through surface slip. We study both the structural and dynamical properties of the largely unknown near-surface regions in polymer solutions and complex liquids by surface sensitive neutron and x-ray scattering which allow to access a so far unexplored time and spatial regime of flowing liquids.

People employed/collaborating within the priority program:

• Dipl. Phys. Philipp Gutfreund (PhD student) employed in Bochum and the Institut Laue-Langevin, Grenoble.
• Dipl. Phys. Marco Walz (PhD student) employed in Erlangen.
• Dr. Max Wolff (scientific assitant) in Bochum and the Institut Laue-Langevin, Grenoble.
• Dipl. Phys. Nicole Voss (PhD student) in Erlangen.
• Stefan Gerth (Diploma student) in Erlangen.

Expertise of the group:

Neutron and X-ray scattering,
complex liquids.

Publications of the group connected with nano- or microfluidics:

• Structure and Textures of Micelles under shear,
  M. Walz, A. Magerl, M. Wolff, H. Zabel,
  Superlattices and Microstructures 41, 185 (2007).


• Crystallisation of F68 micelles,
  M. Wolff, K. Pranzas, A. Magerl, H. Zabel,
  Superlattices and Microstructures 41, 190 (2007).


• NS-SANS for the investigation of micellar systems,
  M. Wolff, A. Magerl , H. Zabel,
  Thin solid films 515, 5724 (2007).


• Flow cell for grazing incident neutron scattering,
  D. van der Grinten, M. Wolff, H. Zabel, A. Magerl,
  Meas. Sci. Technol. 19, 034016 (2008).


• Slip and depletion in a Newtonian liquid,
  M. Wolff, B. Akgun, M. Walz, A. Magerl, and H. Zabel,
  Europhys. Letter 82, 36001 (2008).


• Shear induced relaxation of polymer micelles at the solid-liquid interface
  M. Wolff, R. Steitz, P. Gutfreund, N. Voss, S. Gerth, M. Walz, A. Magerl, H. Zabel,
  Langmuir (submitted).