Dresden 2009 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 19: Focus: Magnetic Soft Matter I
CPP 19.8: Vortrag
Dienstag, 24. März 2009, 12:15–12:30, ZEU 222
Surface Instabilities and Magnetic Soft Matter — •Christian Gollwitzer1, Marina Krekhova2, Günter Lattermann2, Ingo Rehberg1, and Reinhard Richter1 — 1Experimentalphysik V, Universität Bayreuth, 95440 Bayreuth, Germany — 2Makromolekulare Chemie I, Universität Bayreuth, 95440 Bayreuth, Germany
Thermoreversible ferrogels are the most recent incarnation of magnetic soft matter [1]. There mechanical deformation in homogeneous magnetic fields has been studied for the case of a sphere in [2]. We report now on the formation of surface instabilities in a layer of thermoreversible ferrogel when exposed to a vertical magnetic field. Both static and time dependent magnetic fields are employed. Under variations of temperature, the viscoelastic properties of our soft magnetic matter can be tuned. Stress relaxation experiments unveil a critical scaling behaviour of the relaxation time, as predicted in [3]. The resulting magnetic threshold for the formation of Rosensweig-cusps is measured for different temperatures, and compared with theoretical predictions [4]. Details can be found in the preprint [5].
[1] G. Lattermann and M. Krekhova, Macromol. Rapid Commun., 2006, 27, 1373–1379
[2] C. Gollwitzer, A. Turanov, M. Krekhova, G. Lattermann, I. Rehberg, and R. Richter, J. Chem. Phys., 2008, 128, 164709.
[3] P. G. de Gennes, Macromolecules, 2002, 35, 3785–3786.
[4] S. Bohlius, H. Brand, H. Pleiner, and M. Gels, Z. Phys. Chem, 2006, 220, 97–104.
[5] http://arxiv.org/abs/0811.1526