Modeling and finite element simulation of the chemo-magneto-mechanical behavior of magnetic polymer gels

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Multi-functional materials are - due to their stimuli-responsive properties - predestined for actuator and sensor applications e.g. in microfluidics or in medical engineering. Important representatives of this group of materials are polymers, which are sensitive towards externally applied electric and magnetic fields and thus enable a controlled deformation.In the present proposal, the behavior of ferrogels, i.e. polymer gels with magnetic particles, under an external magnetic field will be studied in detail. The modeling and simulation of the (chemo-)magneto-mechanical behavior will be investigated by using finite elements. The ferrogel consisting of a polymer network, a liquid phase, and fixed or mobile magnetic particles will be described on basis of a theory of porous media for the different phases. The formulation of the complete system is realized by coupling the mechanical and the magnetic field equations. The parameters for the material model will be obtained from experimental and theoretical/numerical investigations on the microscale from project partners. In the framework of the project, the influence of the external magnetic field on the particles and the interactions of the particles with the polymer network as well as the resulting shape change due to an applied magnetic field will be investigated. For isotropic and anisotropic gels – with fixed and/or mobile magnetic particles – the behavior in a magnetic field will be computed and then compared to results from experimental partners within the SPP. For this, the magneto-mechanical hysteretic behavior of ferrogels will be analyzed and then afterwards integrated in the developed model. In the following, also mobile charged particles will be considered. As a result, the deformation behavior of polymer gels under electric and magnetic fields can be determined by numerical simulations.By cooperating with the experimental partners within the SPP, the quality of the derived chemo-electro-magneto-mechanical formulation will be improved consistently. Thus, a thermodynamically consistent model as numerical tool will be made available, which enables the modeling and simulation of ferrogel actuator configurations which are important for applications in medicine and in microfluidics.