000189646 001__ 189646
000189646 005__ 20181203023301.0
000189646 0247_ $$2doi$$a10.1039/c3cp43306d
000189646 022__ $$a1463-9076
000189646 02470 $$2ISI$$a000319006100043
000189646 037__ $$aARTICLE
000189646 245__ $$aFree volume in ionic liquids: a connection of experimentally accessible observables from PALS and PVT experiments with the molecular structure from XRD data
000189646 260__ $$aCambridge$$bRoyal Soc Chemistry$$c2013
000189646 269__ $$a2013
000189646 300__ $$a10
000189646 336__ $$aJournal Articles
000189646 520__ $$aIn the current work, free volume concepts, primarily applied to glass formers in the literature, were transferred to ionic liquids (ILs). A series of 1-butyl-3-methylimidazolium ([C4MIM](+)) based ILs was investigated by Positron Annihilation Lifetime Spectroscopy (PALS). The phase transition and dynamic properties of the ILs [C4MIM][X] with [X](-) = [Cl](-), [BF4](-), [PF6](-), [OTf](-), [NTf2](-) and [B(hfip)(4)](-) were reported recently (Yu et al., Phys. Chem. Chem. Phys., 2012, 14, 6856-6868). In this subsequent work, attention was paid to the connection of the free volume from PALS (here the mean hole volume, < v(h)>) with the molecular structure, represented by volumes derived from X-ray diffraction (XRD) data. These were the scaled molecular volume V-m,V-scaled and the van der Waals volume V-vdw. Linear correlations of < v(h)> at the "knee'' temperature (< v(h)>(T-k)) with V-m,V-scaled and V-vdw gave good results for the [C4MIM](+) series. Further relationships between volumes from XRD data with the occupied volume V-occ determined from PALS/PVT (Pressure Volume Temperature) measurements and from Sanchez-Lacombe Equation of State (SL-EOS) fits were elaborated (V-occ(SL-EOS) approximate to 1.63 V-vdw, R-2 = 0.981 and V-occ(SL-EOS) approximate to 1.12 V-m,V-scaled, R-2 = 0.980). Finally, the usability of V-m,V-scaled was justified in terms of the Cohen-Turnbull (CT) free volume theory. Empirical CT type plots of viscosity and electrical conductivity showed a systematic increase in the critical free volume with molecular size. Such correlations allow descriptions of IL properties with the easily accessible quantity V-m,V-scaled within the context of the free volume.
000189646 700__ $$aBeichel, Witali$$uUniv Freiburg, Freiburger Mat Forschungszentrum, D-79104 Freiburg, Germany
000189646 700__ $$aYu, Yang$$uNanjing Univ Informat Sci & Technol, Sch Phys & Optoelect Engn, CN-210044 Nanjing, Jiangsu, Peoples R China
000189646 700__ $$aDlubek, Guenter$$uITA Inst Innovat Technol, D-06120 Lieskau, Germany
000189646 700__ $$aKrause-Rehberg, Reinhard$$uUniv Halle Wittenberg, Inst Phys, D-06120 Halle, Saale, Germany
000189646 700__ $$aPionteck, Juergen$$uLeibniz Inst Polymerforsch Dresden eV, D-01069 Dresden, Germany
000189646 700__ $$aPfefferkorn, Dirk$$uUniv Halle Wittenberg, Inst Chem Phys Chem Polymere, D-06099 Halle, Saale, Germany
000189646 700__ $$aBulut, Safak$$uEcole Polytech Fed Lausanne, Inst Sci & Ingn Chim, CH-1015 Lausanne, Switzerland
000189646 700__ $$aBejan, Dana
000189646 700__ $$aFriedrich, Christian$$uUniv Freiburg, Inst Anorgan & Analyt Chem, D-79104 Freiburg, Germany
000189646 700__ $$0240933$$aKrossing, Ingo$$g166101$$uUniv Freiburg, Freiburger Mat Forschungszentrum, D-79104 Freiburg, Germany
000189646 773__ $$j15$$k22$$q8821-8830$$tPhysical Chemistry Chemical Physics
000189646 909C0 $$0252182$$pLCIC
000189646 909CO $$ooai:infoscience.tind.io:189646$$particle
000189646 937__ $$aEPFL-ARTICLE-189646
000189646 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED
000189646 980__ $$aARTICLE