Regensburg 2013 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 47: Charged Soft Matter

CPP 47.5: Vortrag

Freitag, 15. März 2013, 10:45–11:00, H34

Rotational and translational diffusion of ionic liquids confined in nanoporous silica — •Ciprian Ghiorghita Iacob, Joshua Sangoro, Wycliffe Kipnusu, Jörg Kärger, and Friedrich Kremer — Institute of Experimental Physics I, Leipzig, Germany

Charge transport and glassy dynamics of several classes of ionic liquids confined in uni-directional nanoporous silica membranes are investigated in a wide frequency and temperature range by a combination of Broadband Dielectric Spectroscopy (BDS), Pulsed Field Gradient Nuclear Magnetic Resonance (PFG NMR) and Fourier Transform Infrared spectroscopy (FTIR). Two opposite effects are observed: (i) surface effects and (ii) confinement effects. More than 10-fold systematic decrease in the effective diffusion coefficient (for HMIM+ -based ionic liquids with PF6 -, I-, Cl-, Br- anions) from the bulk value is observed in the silica nanopores. For a second category of ILs including BF4- and NTf2 -based ionic liquids, it is experimentally demonstrated that the ionic mobility at lower temperatures is enhanced by more than two decades under nano-confinement in comparison to the bulk value. In summary, the resultant macroscopic transport properties of glass-forming ionic liquids in confining space are determined by a subtle interplay between surface- and confinement- effects [1-4].

References: [1]. Iacob, C., (2008) J. Chem. Phys., 129 (23) 234511, [2]. Iacob, C., et al. (2010). Phys. Chem. Chem. Phys., 12, 13798-13803, [3]. Iacob, C., et al. (2011). Soft Matter, 8, 289-293, [4]. Kremer, F., Schönhals, A.,(2003) Broadband Dielectric Spectroscopy. , Berlin: Springer.