Seminar: Materials on the meso-scale: The neutrons view

In soft and hybride materials the macroscopic properties are related to structure and dynamics on the meso-scale. This provides large flexibility in the design of materials but is challenging for theory to describe, as a wide range of time and length scales have to be considered. In this presentation I will present two material systems, which can be well studied with neutron scattering methods. Polymer systems are characterised by viscoelastic properties, which make them very interesting for applications in many areas of technology. The strong non-linearities in the response functions are related to the wide range of length and times scales relevant on the molecular level as well as to the binding energies, which are close to ambient thermal energies. Apart from the changes on the molecular scale strong non-linearities may lead to macroscopic flow instabilities, sometimes having similar macroscopic signatures. In this presentation I will show results relating self-assembly as well as topological interactions in polymer systems to their viscoelastic properties. These results are complemented by experimental results probing macroscopic flow instabilities. Magnetic liquids provide large flexibility for tuning the interaction between the constituents. This allows to control self assembly and the formation of well defined structures in a bottom up approach. Depending on the shape, size and moment of the magnetic particles the self assembly process may result in well ordered crystalline assembly or defect rich open network structures. In this presentation I will summarise results on the phase formation in a two dimensional binary magnetic liquid and discuss possibilities for layer by layer deposition on solid substrates. For the scientific areas above neutron scattering methods contribute key information. I will conclude the presentation by providing a perspective on how this research will benefit from the unique opportunities becoming available once the European Spallation Source comes on line.