Project C2

Determination of electron-density profiles of switchable polymer-films

Prof. Dr. rer. nat. B. Stühn

Physics of Condensed Matter
Institut für Festkörperphysik
TU Darmstadt – Fachbereich Physik
S2|04 116
Hochschulstr. 8
64289 Darmstadt
Tel.: +49 6151 16-2783

In situ determination of the electron density profile of switchable thin polymer films. Polymers in thin films may change their conformation under the influence of an external electric or magnetic field or light. The response of the polymer to the external trigger is expected to depend on the type of immobilization at the substrate. It is therefore important to study thin films of polymers that are grafted to a substrate, coated onto a substrate or are floating as a monomolecular layer on a liquid surface. A direct way to study the density variation of the polymer film close to the interface is to use the reflection of X-rays from the film. The intensity of the reflected X-ray beam varies with the angle of reflexion and may be used to calculate the density profile. In this project we will develop a method to determine the reflection profiles of polymer films in situ, i.e. while the film is exposed to the external stimulus (magnetic/electric field or light). Results from these experiments will be compared with structural studies using small-angle X-ray scattering and dynamic light scattering. Parts of the project will have close interactions with projects A1, B1, and C1.…stuehn/