Regensburg 2007 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 7: POSTER: INTERNAL SYMPOSIUM Scattering Experiments

CPP 7.30: Poster

Monday, March 26, 2007, 16:00–18:00, Poster B

Microemulsion-Polymer Systems Studied with Elastic and Inelastic Neutron Scattering — •Tinka Spehr^{1, 2}, Bernhard Frick¹, and Bernd Stuehn² — ¹Institut Laue-Langevin, Grenoble, France — ²Institute of Solid State Physics, TU Darmstadt, Germany

We study a microemulsion consisting of water, decane or toluene and AOT forming water-in-oil droplets. The addition of amphiphilic triblock copolymer leads to the interconnection of the droplets. We are investigating the structural and dynamical behavior of this model system for a transiently linked network with different neutron scattering techniques. Also this system is used to realize soft confinement of the water. Neutron Small Angle Scattering showed increasing ordering of the droplets upon polymer addition. Measurements on pure microemulsions have been carried out on a time-of-flight and a neutron backscattering instrument to study the effect of spatial soft confinement on water. Two different droplet sizes have been investigated (diameters of about 3 and 10 nm). Elastic scans from 315 K to 2 K showed a deeper undercooling of the water confined in the smaller droplets. Inelastic scans have been carried out at temperatures between 300 K and 250 K. The dynamic structure factor displays a complex shape clearly deviating from one single Lorentzian. The combination of spatial restriction and wall effects on the dynamics will be discussed. Neutron Spin Echo can probe shape fluctuations of the droplet shell [3]. We investigated the effect of polymer addition on the elastic properties of the surfactant shells.

[2] J. Huang, S. Milner, B. Farago, D. Richter (1987), PRL 59, 2600