Berlin 2018 – scientific programme
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 73: Functional Polymer Hybrids and Composites
CPP 73.5: Talk
Thursday, March 15, 2018, 16:00–16:15, PC 203
Density functional theory for ferrogels and magnetorheological elastomers — Peet Cremer1, Marco Heinen2, •Andreas M. Menzel1, and Hartmut Löwen1 — 1Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany — 2Universidad de Guanajuato, Guanajuato, Mexico
Locking the positions of magnetic or magnetizable colloidal particles in an elastic polymer matrix leads to an interesting class of composite materials. One remarkable feature is that their overall mechanical properties can be reversibly tuned from outside by magnetic fields.
Our scope was to establish a statistical approach to this situation in terms of classical density functional theory, including thermal fluctuations [1]. To lower the complexity, we mapped the problem to a suitable one-dimensional dipole-spring model. A central issue is that classical density functional theory was constructed to describe liquid-like states, in contrast to our fixed particle positions in the elastic matrix. We solved this problem by introducing suitable particle pair and external potentials to mimic corresponding elastic interactions. Comparison with Monte-Carlo simulations showed good agreement. In parts, the theory uses input from explicit analytical calculations of the elastic response of the polymer matrix [2,3].
The theory allows to calculate, for instance, the change in the elastic modulus for varying strengths of the magnetic particle interactions.
[1] P. Cremer et al., J. Phys.: Condens. Matter 29, 275102 (2017).
[2] M. Puljiz et al., Phys. Rev. Lett. 117, 238003 (2016).
[3] M. Puljiz et al., Phys. Rev. E 95, 053002 (2017).