Dielectric spectroscopy study on ionic liquid microemulsion composed of water, TX-100, and BmimPF6

Abstract

Articles you may be interested inWe report here a broadband dielectric spectroscopy study on an ionic liquid microemulsion (ILM) composed of water, Triton X-100 (TX-100), and 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF 6 ). It is found that the phase behavior of this ILM can be easily identified by its dielectric response. The dielectric behavior of the ILM in the GHz range is consistent with that of TX-100/water mixtures with comparable water-to-TX-100 weight ratio. It consists of the relaxations due to ethylene oxide (EO) unit relaxation, hydration water dynamics, and/or free water dynamics. The water content dependence of the EO unit relaxation suggests that this relaxation involves dynamics of hydration water molecules. In the IL-in-water microemulsion phase, it is found that bmimPF 6 molecules are preferentially dissolved in water when their concentration in water is lower than the solubility. An additional dielectric relaxation that is absent in the TX-100/water mixtures is observed in the frequency range of 10 7 -10 8 Hz for this ILM. This low-frequency relaxation is found closely related to the bmimPF 6 molecule and could be attributed to the hopping of its cations/anions between the anionic/cationic sites.

Evolution of Dielectric Behavior of Regenerated Cellulose Film during Isothermal Dehydration Monitored in Real Time via Dielectric Spectroscopy

“…It is constant at low frequencies as a result of charge transport on infinite “percolation” paths (dc conductivity) and becomes frequency dependent at higher frequency range where charge transports via hopping in finite clusters (ac conductivity), which behaves as a dielectric relaxation. Due to the same underline mechanism, the dc conductivity is correlated with the strength of the relaxation of ac conductivity by the empirical Barton-Nakajima-Namikawa (BNN) relation expressed as [27,28,29], σDC=pε0Δε/τm where p is correlation factor which varies with the microscopic structure and composition of the system, and τm is the characteristic relaxation time, which approximates the hopping time defined as the time for charge carriers attempting to overcome the highest energy barrier [27,30,31]. In Figure 3a, the product of τ1 and σDC with a correlation factor value of 0.7 is displayed.…”

“…As discussed above, the relaxation 1 has the same underline mechanism as dc conductivity, while the relaxation 2 should be due to interfacial polarization. According to the Einstein and Einstein-Smoluchowski relations, dc conductivity is related to the hopping time (τe) by [30,31] σDC=nq2λ22kBTτe where n is the effective number density of the charge carrier, q is the elementary electric charge, kB is the Boltzmann constant, T is absolute temperature, and λ is the hopping length. Consider τe≈τ1, Δε1 (on the order of product of σDC and τe) is mainly functions of n and λ , according to Equation (4).…”

Local structures of ionic liquids in the presence of gold under high pressures

“…• C. [1][2][3][4][5][6][7][8] Ionic liquids have attracted more and more attention owing to their dual nature as both salts and fluids. Furthermore, ionic liquids have peculiar properties like negligible vapor pressure, wide liquid range, high electrical conductivity, and tunable miscibility.…”

Dielectric relaxation of nonaqueous ionic liquid microemulsions: polarization, microstructure, and phase transition

“…Aer that, the dielectric measurements of ILs microemulsions which constructed by IL and TX-100 with water or oil were also respectively performed as mentioned above. 32,35,40 In these measurements, researchers observed another relaxation of higher radio frequency 10 7 to 10 8 Hz. Nevertheless, just as what have been used to interprete the relaxation of the IL/TX-100/water system, many possible relaxation mechanisms may contribute to this relaxation.…”