Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 16: Interfaces and Thin Films II (joint session with DECHEMA and VDI)
CPP 16.10: Vortrag
Dienstag, 12. März 2013, 12:15–12:30, H40
Electric polarization in thin films of polyvinylidene fluoride doped with the ionic liquid 1-ethyl-3-methylimidazolium nitrate — •Alexander Lack, Peter Frübing, Feipeng Wang, and Reimund Gerhard — Applied Condensed-Matter Physics Group, Department of Physics and Astronomy, Faculty of Science, University of Potsdam, Karl-Liebknecht-Strasse 24-25, 14476 Potsdam, Germany
Dielectric properties of spin-coated polyvinylidene fluoride (PVDF) films containing a small amount (0.01 - 10 wt%) of the ionic liquid (IL) 1-ethyl-3-methylimidazolium nitrate [EMIM+][NO3−] and sandwiched between aluminium electrodes are investigated. Films with more than about 1 wt% IL exhibit pronounced current-voltage hysteresis which indicates the existence of a ferroelectric polarization. The dielectric spectra show pronounced charge-carrier polarizations with huge permittivities. In films with more than 0.1 wt% IL electrode polarization dominates. From its signatures the DC conductivity is estimated: for films with 1 wt% IL values of 10−7 and 10−4 S/cm are found at room temperature and 100 ∘C, respectively. The relaxation associated with the glass transition in PVDF tends to disappear for samples containing more than 1 wt% IL, though the crystallinity is only moderately enhanced. These findings refer to an ordered crystalline structure where ions are immobilized by Coulomb interaction with molecular dipoles within the polymer chain. The details of this interaction have still to be understood.