Berlin 2018 – scientific programme

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MA: Fachverband Magnetismus

MA 1: Magnetic nanoparticles (joint session MA/CPP)

MA 1.8: Talk

Monday, March 12, 2018, 11:30–11:45, H 0112

Studying the dynamic properties of pure cobalt ferrite nanoparticles and particles coated with silica in PEG-solution by magnetic AC-susceptometry — •Samira Webers¹, Melissa Hermes², Joachim Landers¹, Soma Salamon¹, Annette M. Schmidt², and Heiko Wende¹ — ¹Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), University of Duisburg-Essen — ²Institute for Physical Chemistry, University of Cologne

The particle-matrix interaction in complex viscoeleastic composites is determined by the characteristic length scales between the magnetic particles and matrix structures. In this work, we study the particle-matrix interaction of a polyethylene glycol (PEG) polymer solution with tailored complexity and the mobility of two types of particles. Pure cobalt ferrite nanoparticles with a hydrodynamic radius of r_h,CFO=23.2nm and cobalt ferrite particles coated with silica resulting in r_h,CFO@SiO2=42.3nm are dispersed in various concentrated polymer solutions with different PEG length. The dynamic properties of the two particle systems in various polymer solutions are characterized by magnetic AC-susceptometry. Here the Brownian relaxation of the particles in complex fluids are investigated in the frequency regime from 0.001 Hz -250 kHz and compared to the relaxation of the coated particles, where a shift of magnetic susceptibility spectra to lower frequencies is observed. The frequency dependent viscosity is also determined by temperature dependent magnetic AC measurements. This work is supported by the DFG-Priority Programme SPP1681.