Temperature Dependence of the Viscosity and Conductivity of Mildly Functionalized and Non‐Functionalized [Tf2N]− Ionic Liquids |
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Authors: | Dr Safak Bulut Dr Philipp Eiden Witali Beichel Dr John M Slattery Dr Tom F Beyersdorff Dr Thomas J S Schubert Prof Dr Ingo Krossing |
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Institution: | 1. Albert‐Ludwigs‐Universit?t Freiburg, Institut für Anorganische und Allgemeine Chemie, Freiburg Institute of Advanced Studies (FRIAS);2. Freiburger Materialforschungszentrum (FMF), Albertstr. 21, D‐79104 Freiburg (Germany), Fax: (+49)?761‐203‐6001;3. Department of Chemistry, University of York, Heslington, York YO10 5DD (United Kingdom).;4. IoLiTec Ionic Liquids Technologies GmbH, Salzstrasse 184, D‐74076 Heilbronn (Germany) |
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Abstract: | A series of bis(trifluoromethylsulfonyl)imide ionic liquids (ILs) with classical as well as mildly functionalized cations was prepared and their viscosities and conductivities were determined as a function of the temperature. Both were analyzed with respect to Arrhenius, Litovitz and Vogel–Fulcher–Tammann (VFT) behaviors, as well as in the context of their molecular volume (Vm). Their viscosity and conductivity are highly correlated with Vm/T or related expressions (R2≥0.94). With the knowledge of Vm of new cations, these correlations allow the temperature‐dependent prediction of the viscosity and conductivity of hitherto unknown, non‐ or mildly functionalized ILs with low error bars (0.05 and 0.04 log units, respectively). The influence of the cation structure and mild functionalization on the physical properties was studied with systematically altered cations, in which Vm remained similar. The To parameter obtained from the VFT fits was compared to the experimental glass temperature (Tg) and the Tg/To ratio for each IL was calculated using both experimental values and Angell’s relationship. With Walden plots we investigated the IL ionicity and interpreted it in relation to the cation effects on the physical IL properties. We checked the validity of these Vm/T relations by also including the recently published variable temperature viscosity and conductivity data of the Al(ORF)4]? ILs with RF=C(H)(CF3)2 (error bars for the prediction: 0.09 and 0.10 log units, respectively). |
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Keywords: | conductivity ionic liquids molecular volume temperature dependence viscosity |
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