Surfaces of Ionic Liquids

Nakajima, K.; Lı́sal, Martin; Kimura, Kenji

doi:10.1002/9783527680597.ch53

Cited by 11 publications

(10 citation statements)

References 81 publications

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“…In a recent approach [16], experimental ARXPS results were combined with MD simulations to represent the surface tension values of the homologous series of [C n C 1 Im] + -based ILs by contributions from different segments terminating the surface, considering their volume fractions. For binary IL mixtures being of interest here, different theoretical and empirical approaches have been discussed in the literature, as it has been reviewed by, e.g., Smoll et al [12] and Nakajima et al [70]. A comparison with relevant approaches is not possible for the present IL mixture due to the lack of required input information.…”

Section: Prediction Methods For Il Mixturesmentioning

confidence: 99%

“…This non-ideal behavior has also been found by, e.g., Smoll et al [12] for binary IL mixtures with a common anion and two non-fluorinated [C n C 1 Im] + cations of different alkyl chain lengths (n = 2 and 12). All this indicates that instead of bulk compositions, surface compositions need to be considered in appropriate prediction schemes [12,70].…”

Section: Prediction Methods For Il Mixturesmentioning

confidence: 99%

“…Since this molar surface concentration is directly accessible by, e.g., ARXPS, it may be of advantage in comparison to commonly used surface volume or area concentrations of IL molecules (see in Refs. [12,70]) which can hardly be determined.…”

Section: Prediction Methods For Il Mixturesmentioning

confidence: 99%

See 2 more Smart Citations

Surface Tension and Viscosity of Binary Mixtures of the Fluorinated and Non-fluorinated Ionic Liquids [PFBMIm][PF6] and [C4C1Im][PF6] by the Pendant Drop Method and Surface Light Scattering

et al. 2020

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Mixtures of fluorinated and non-fluorinated ionic liquids (ILs) show a distinct structural organization in the bulk and at the surface. To understand how such microscopic effects influence the macroscopic bulk and surface properties of IL mixtures, knowledge of corresponding thermophysical properties including viscosity and surface tension is required yet lacking. With the intention of investigating surface enrichment effects of the fluorinated IL [PFBMIm][PF 6 ] (3-methyl-1-(3,3,4,4,4pentafluorobutyl)imidazolium hexafluorophosphate) in mixtures with the structurally similar, non-fluorinated IL [C 4 C 1 Im][PF 6 ] (1-butyl-3-methylimidazolium hexafluorophosphate) observed with angle-resolved X-ray photoelectron spectroscopy (ARXPS), the pendant drop method and surface light scattering (SLS) were applied in the present study to determine surface tension and dynamic viscosity between (293 and 368) K. By adding small amounts of [PFBMIm][PF 6 ] up to 9 mol %, a distinct increase in the viscosity and decrease in the surface tension of the mixtures relative to the properties of pure [C 4 C 1 Im][PF 6 ] was found. This behavior reflects the nanosegregated structure in the bulk and at the surface of the binary IL mixtures. Using the results about the pronounced surface enrichment of the fluorinated chain of [PFBMIm][PF 6 ] quantified by ARXPS, a linear mixing rule for the surface tension of the IL mixtures based on the surface tensions of the pure ILs and the surface concentration of their most surface-active groups is suggested.

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Section: Prediction Methods For Il Mixturesmentioning

confidence: 99%

Section: Prediction Methods For Il Mixturesmentioning

confidence: 99%

See 1 more Smart Citation

Surface Tension and Viscosity of Binary Mixtures of the Fluorinated and Non-fluorinated Ionic Liquids [PFBMIm][PF6] and [C4C1Im][PF6] by the Pendant Drop Method and Surface Light Scattering

et al. 2020

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“…Therefore, the structure of the vacuum/IL interface has been in the center of surface science investigations using different techniques like molecular dynamics calculations, [21] X‐ray reflectivity, [22] direct recoil spectrometry, [23] Rutherford backscattering,[ 23b , 24 ] low energy ion scattering, [25] reactive atom scattering, [26] sum frequency generation vibrational spectroscopy [27] and X‐ray photoelectron spectroscopy (XPS). [28] Thereby, a good understanding of the static properties of this interface has been obtained.…”

Section: Introductionmentioning

confidence: 99%

n‐Butane, iso‐Butane and 1‐Butene Adsorption on Imidazolium‐Based Ionic Liquids Studied with Molecular Beam Techniques

Winter

Bhuin

Maier

et al. 2021

Chemistry A European J

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The interaction of molecules, especially hydrocarbons, at the gas/ionic liquid (IL) surface plays a crucial role in supported IL catalysis. The dynamics of this process is investigated by measuring the trapping probabilities of nbutane, iso-butane and 1-butene on a set of frozen 1-alkyl-3methylimidazolium-based ILs [C n C 1 Im]X, where n = 4, 8 and X À =Cl À , Br À , [PF 6 ] À and [Tf 2 N] À . The decrease of the initial trapping probability with increasing surface temperature is used to determine the desorption energy of the hydrocarbons at the IL surfaces. It increases with increasing alkyl chain length n and decreasing anion size for the ILs studied. We attribute these effects to different degrees of alkyl chain surface enrichment, while interactions between the adsorbate and the anion do not play a significant role. The adsorption energy also depends on the adsorbing molecule: It decreases in the order n-butane > 1-butene > iso-butane, which can be explained by different dispersion interactions.

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“…In essence, RTILs are solventless organic salts that remain liquid to below 100°C, due to the bulky and irregular shapes, and non-localized charges, of their ions. [1,2] The spectacular rise in their study [3,4] since the 1990's owes to their exceptional potential for numerous diverse applications. [5][6][7][8][9] Their great interest for basic science stems from their near-unique combination of interactions, [2,10,11] anomalous properties, [12] and intriguing hierarchical structure on a broad range of length scales.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Structure in Short‐Chain Ionic Liquids

2020

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The temperature (T) and cationic chain length (n) evolution of the nanoscale structure of the sub‐layering‐threshold members of a model family of room temperature ionic liquids (RTILs) is investigated by x‐ray scattering. The measured curves are computer‐resolved into individual Teubner‐Strey‐like lineshapes. The polar‐apolar layering is found to start at n=3 . Opposite n‐trends are found at n≤3 for the spacings and correlation lengths associated with the diffraction patterns’ two main peaks, and assigned to a shift of balance between the two main interactions, Coulomb and van der Waals, and to increasing packing constraints due to the addition of methylenes. The spacings’ thermal expansion coefficients are found to deviate from the macroscopically‐measured values, and to anomalously decrease with increasing temperature. Finally, the reduced temperature scale, t=(T-Tm)/Tm , (Tm= melting temperature), is demonstrated to render the observed trends significantly more systematic than those on a conventional T scale.

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Surfaces of Ionic Liquids

Cited by 11 publications

References 81 publications

Surface Tension and Viscosity of Binary Mixtures of the Fluorinated and Non-fluorinated Ionic Liquids [PFBMIm][PF6] and [C4C1Im][PF6] by the Pendant Drop Method and Surface Light Scattering

Surface Tension and Viscosity of Binary Mixtures of the Fluorinated and Non-fluorinated Ionic Liquids [PFBMIm][PF6] and [C4C1Im][PF6] by the Pendant Drop Method and Surface Light Scattering

n‐Butane, iso‐Butane and 1‐Butene Adsorption on Imidazolium‐Based Ionic Liquids Studied with Molecular Beam Techniques

Nanoscale Structure in Short‐Chain Ionic Liquids

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