Project Details
Projekt
Dynamic magnetic investigations of the particle-matrix interaction in magnetic hybrid materials
Applicant
Professor Dr. Frank Ludwig
Subject Area
Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
Experimental Condensed Matter Physics
Experimental Condensed Matter Physics
Term
from 2013 to 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 238074956
Goal of the project is the continuation of the application of measurement techniques (MRX and ACS), developed and established in the first two SPP1681 promotion periods, for the characterization of the dynamic magnetic properties of magnetic nanoparticles (MNP) in various particle-matrix hybrid systems. These measurements shall provide a better understanding of the particle-matrix interactions and of the magnetic controllability of the matrix properties. The response of a MNP to a time-varying magnetic field allows the estimation of the characteristic time constant which – proposed that the MNP are thermally blocked – provides information on the local embedding of the particle in the matrix. One focus of the activities in the third promotion period is the temperature dependent investigation of the influence of a magnetic field on the particle-matrix interaction. For this, a portfolio of unique measurement methods is available which allow both the variation of temperature up to about 80°C and the application of static magnetic fields up to more than 10 mT. Related to the experimental techniques is the development of theoretical models which allow the determination of rheological parameters from the measured signals. For this, the studies on specific model systems will be continued which will be performed in tight collaboration with project partners – especially the working group "Rheology". This includes non-Newtonian fluids, such as PEG solutions, as well as viscoelastic matrices (crosslinked hydrogels). The materials parameters, such as dynamic viscosity and shear module, derived from nanorheological measurements and especially their magnetic field dependence will be compared to the values obtained from macrorheological measurements in order to advance the multiscale understanding of magnetorheological effects. The multiscale studies also imply the use of MNP with different sizes. Besides the MNP systems studied so far, blocked multicore MNPs with diameters above 100 nm will also be included in the studies. Temperature dependent measurements will be performed in collaboration with project partners especially for the investigation of the sol-gel transition and the size change of thermoreversible NIPAM gel spheres. The investigation of the magnetic field dependence of Brownian and Neel time constants and their comparison with the results from Mössbauer spectroscopy will be continued. The methods for the magnetorheological characterization of particle-matrix hybrid systems which have been developed in collaboration with various SPP1681 partners will be consolidated and applied on technically and biomedically relevant material systems. The obtained results will be given to other project partners in order to verify their theoretical models.
DFG Programme
Priority Programmes
Co-Investigator
Professor Dr. Meinhard Schilling
