Insights on cholinium- and piperazinium-based ionic liquids under external electric fields: A molecular dynamics study

Abstract

The rotational and translational response of cholinium benzoate, cholinium salicylate, piperazinium benzoate, and piperazinium salicylate to static and dynamic external electric fields was studied using non-equilibrium molecular dynamics simulations. The existence of strong intrinsic electric fields in the studied fluids requires intensities larger than 0.25 V Å(-1) to obtain remarkable changes in the fluids' properties, such as rotational motion, dipolar alignment, or ion diffusivities. Very effective dipolar alignment with the applied fields is obtained showing rotational motions in the direction of the applied field, increasing with field intensity and decreasing with field frequency. Translational movement is clearly improved by the applied fields specially for strong fields and low frequencies, which lead to ionic diffusivities increasing up to two orders of magnitude for the stronger fields in comparison with zero field situations, and thus, increasing remarkably fluids' electrical conductivity. The effect of external electric fields on the studied ionic liquids is weaker than in common imidazolium-based ionic liquids.

A theoretical study on ionic liquid endohedral C540 fullerene

“…Nevertheless, the contribution of the dri motion is strongly dependent on the intensity of the applied eld; results previously reported by our group showed that in the case of CH_BE this contribution is almost negligible for elds lower than 0.10 V Â ÅÀ1 . 50 Therefore, using kinetic thermostats for the studied systems should lead to reliable results, which is in agreement with the simulations of ILs under moderate EEFs available in the literature. [51][52][53][54] Similarly, kinetic thermostats were also used for the simulation on EHFs under EEFs.…”

“…For comparison, the behaviour of an empty C540 fullerene, 1 Â PRIST_C540_IL, under EEFs was also studied. In a recent work, 72 our group reported a study on the behaviour of bulk CH_BE (among other ILs) under EEFs. These previous results showed that CH_BE has an intrinsic electric eld of 0.36 V ÅÀ1 and 0.31 V ÅÀ1 for BE and CH ions, respectively.…”

On the Miscibility and Immiscibility of Ionic Liquids and Water

“…In a separate study, Nishi et al employed X-ray reflectivity measurement and showed that the interfacial structure of water and a hydrophobic IL, TOMA/TFPB, changes markedly upon external voltage modulation. Numerous studies have demonstrated that external electric fields can have a significant effect on the structure and dynamics of neat ILs, − and it is thus reasonable to assume similar effects for concentrated electrolyte mixtures. These observations suggest that long-range electrostatic forces play a significant role in determining IL phase behavior, including IL/water mixing, and this hypothesis is verified in this work.…”

Behavior of Deep Eutectic Solvents under External Electric Fields: A Molecular Dynamics Approach

“…Although it might be argued that the development of nonequilibrium MD simulations under EEFs might have some issues particularly with the use of kinetic thermostats such as Nosé–Hoover thermostat, , the errors induced by the application of kinetic thermostats in nonequilibrium MD simulations under EEFs are negligible for fields with amplitudes lower than 0.1 V Å –1 and very minor for the 0.1–0.25 V Å –1 range; thus, Nosé–Hoover thermostat can be applied for MD simulations under EEFs with amplitudes lower than 0.25 V Å –1 …”

“…The literature on the related IL compounds is also scarce. − The interest on the behavior of DESs under EEFs stands on the possible application of these fluids in technologies such as microwave synthesis or dipolar heating . Moreover, it may be expected that the properties of DESs will change remarkably upon application of EEFs, similar to those of ILs; thus, property tuning through EEFs can be considered especially for properties which have a large impact on technological applications such as viscosity or molecular diffusion.…”