Berlin 2012 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 17: Magnetic Measurement Methods

MA 17.5: Vortrag

Dienstag, 27. März 2012, 12:45–13:00, EB 202

Estimation of the local elastic properties of gelatine gels by magnetization measurements using nickel nanorods as probes — •Philipp Bender, Andreas Tschöpe, and Rainer Birringer — Universität des Saarlandes FR 7.2 Experimentalphysik, Saarbrücken, Deutschland

In recent years particle-based micro- and nanorheology became an emerging field of interest. In particular the investigation of the local structure of heterogenous networks such as physical hydrogels offers new inside into their microstructural makeup.

The present study focuses on the estimation of the local shear modulus of gelatine gels with nickel nanorods as magnetic phase via magnetization measurements. The nanorods were synthesized by electro-deposition of nickel into porous alumina templates, released into aqueous dispersion by dissolution of the alumina layer and further processed to gelatine-based ferrogels. The nanorods are mechanically linked to the polymer network and exhibit - without further pretreatment - isotropic orientation distribution. However, applying an external homogenous magnetic field during the gelation process enabled the preparation of magnetically textured ferrogels. Depending on the ferrogels elastic compliance the nanorods can rotate in field direction in a homogenous magnetic field, working against the mechanical torque, which is caused by the shear deformation of the gel matrix. In this presentation it will be shown that the shear modulus of the surrounding gel matrix can be estimated from the rotation angle of the nanorods as a function of the magnetic torque.