Viscous Flow and Electrical Conductance in Ionic Liquids: Temperature and Composition Dependence in the Light of the Zero Mobility Concept

Abstract

Using the concept of vanishing mobility consequent on the Gibbs-Dimarzio interpretation of the liquidglass transition, it is shown by a quasiempirical treatment of the data that the isothermal composition dependence of transport at low temperatures may be understood, and expressed analytically, on the basis that the zero mobility temperature To, is the only composition-dependent parameter in the transport equation. To reflects the forces of cohesion in the liquid. Simple equations developed on this basis lead to a description of conductance in uni-divalent nitrate melts, and an account of viscous flow in 0-15N concentrated aqueous solutions which is consistent with the electrical-conductance behavior of the same solutions. The usefulness of the Tobolsky and related parameters in describing deviations from additivity in the conductance of mixed molten univalent nitrates is interpreted in the same terms, providing a rational basis for the parallel between kinetic and thermodynamic behavior in these melts. Attention is drawn to the importance of preexponential terms to transport composition dependence at higher temperatures. 6 C.

Interaction and dynamics of (alkylamide + electrolyte) deep eutectics: Dependence on alkyl chain-length, temperature, and anion identity

“…A smaller p value suggests stronger decoupling from medium viscosity and is understood in terms of more pronounced temporal heterogeneity. [27][28][29][30][31][32] Note this result from time-resolved measurements corroborates well with the steady state fluorescence results presented in Fig. 4 which indicated spatial heterogeneity being the strongest for deep eutectics containing CH 3 CH 2 CH 2 CONH 2 .…”

“…[24][25][26] A competition between the lifetime of these domains and the timescale of a reaction occurring in such media then dictates the heterogeneityinduced modulation of a reaction rate. Moreover, different rates of motions of the environmental particles (that is, temporal heterogeneity) [27][28][29][30][31][32] can modify a reaction through dynamic solvent effects. 20,33 Consequently, understanding the heterogeneity aspects of these media is critical from basic scientific point of view.…”

Viscosity of a vitreous potassium nitrate - calcium nitrate mixture

“…Inasmuch as the independent T2* measurements of Loewenstein and Margalit3 also support our results, a remeasurement of the N14 T\ of MeNC is desirable. 14 We conclude, therefore, that there is a real difference between the e\Q/h of MeNC in the gas phase (0.483 ± 0.017 MHz)4 and that in the liquid phase (0.27 MHz).…”

Medium decoupling of dynamics at temperatures ∼100 K above glass-transition temperature: A case study with (acetamide + lithium bromide/nitrate) melts

“…8). Note the pronounced fractional viscosity dependence of τ s is quite reminiscent of viscositydecoupling of diffusion in deeply supercooled liquids, and may therefore indicate presence of both static (distribution of environments) and dynamic heterogeneities (distribution of relaxation times) [35][36][37][38][39][40][41] in these molten mixtures. Surprisingly, dynamic Stokes shift measurements in ionic liquids, systems which are somewhat similar to these multi-component mixtures both in interaction and heterogeneity aspects, do not show fractional SE behavior, 66 even though such a fractional viscosity dependence has been experimentally observed for ion transport in ionic melts.…”

“…The fractional viscosity dependence of these quantities and the consequent departure from the conventional Stokes-Einstein (SE) 33 and Stokes-Einstein-Debye (SED) 34 predictions for these melts are reminiscent of environmental as well as translation-rotation decoupling observed in deeply supercooled liquids. [35][36][37][38][39][40][41] Furthermore, the microheterogeneity and the longer-ranged interactions (mainly those proportional to r −1 , r −2 , and r −3 , r being the distance between two interacting species) 42 present in these systems jointly render a resemblance with many room temperature ionic liquids (IL) where microscopic inhomogeneity [43][44][45][46][47][48][49][50][51][52][53][54][55][56][57] and similar electrostatics govern the liquid properties. The closeness between these melts and dipolar ionic liquids is further evidenced when application of a semi-molecular theory that successfully described the Stokes shift dynamics in ILs and (ionic liquid + polar solvent) binary mixtures [58][59][60][61][62] could also semi-quantitatively predict the solvation time scales and dynamic Stokes shift in (CH 3 CONH 2 + Na/KSCN) and (CH 3 CONH 2 + Ca(NO 3 ) 2 ) melts.…”