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

AIP Advances ◽  
2013 ◽  
Vol 3 (3) ◽  
pp. 032147 ◽  
Author(s):  
Hai-Chou Chang ◽  
Tzu-Chieh Hung ◽  
Hsing-Sheng Wang ◽  
Tsai-Yi Chen
Keyword(s):  
Ionic Liquids ◽  
High Pressures ◽  
Local Structures

scholarly journals Characterization of Local Structures of Confined Imidazolium Ionic Liquids in PVdF-co-HFP Matrices by High Pressure Infrared Spectroscopy

Nanomaterials ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 1973 ◽  
Author(s):  
Teng-Hui Wang ◽  
Ming-Siou Wu ◽  
Hai-Chou Chang
Keyword(s):  
High Pressure ◽  
Ionic Liquids ◽  
Infrared Spectroscopy ◽  
High Pressures ◽  
Vinylidene Fluoride ◽  
Ambient Pressure ◽  
Liquid Polymer ◽  
Local Structures ◽  
Poly Vinylidene Fluoride

The nanoscale ion ordering of ionic liquids at confined interfaces under high pressures was investigated in this study. 1-Hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([HMIM][NTf2])/poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-co-HFP) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([EMIM][NTf2])/PVdF-co-HFP were prepared and characterized by using high-pressure infrared spectroscopy. Under ambient pressure, imidazolium C2–H and C4,5–H absorptions were blue-shifted in frequency due to the presence of PVdF-co-HFP. However, the absorption of anionic νa SO2 did not reveal any significant shifts in frequency upon dilution by PVdF-co-HFP. The experimental results suggest that PVdF-co-HFP disturbs the local structures of the imidazolium C–H groups instead of the anionic SO2 groups. The frequency shifts of C4,5–H became dramatic for the mixtures at high pressures. These results suggest that pressure-enhanced ionic liquid–polymer interactions may play an appreciable role in IL-PVdF-co-HFP systems under high pressures. The pressure-induced blue-shifts due to the PVdF-co-HFP additions were more obvious for the [HMIM][NTf2] mixtures than for [EMIM][NTf2] mixtures.

scholarly journals Structural Reorganization of Imidazolium Ionic Liquids Induced by Pressure-Enhanced Ionic Liquid—Polyethylene Oxide Interactions

2021 ◽  
Vol 22 (2) ◽  
pp. 981
Author(s):  
Teng-Hui Wang ◽  
Li-Wen Hsu ◽  
Hai-Chou Chang
Keyword(s):  
High Pressure ◽  
Ionic Liquids ◽  
Polyethylene Oxide ◽  
High Pressures ◽  
Ambient Pressure ◽  
Structural Reorganization ◽  
Imidazolium Ionic Liquids ◽  
Local Structures ◽  
Electronic Switches ◽  
Pressure Phase

Mixtures of polyethylene oxide (PEO, M.W.~900,000) and imidazolium ionic liquids (ILs) are studied using high-pressure Fourier-transform infrared spectroscopy. At ambient pressure, the spectral features in the C–H stretching region reveal that PEO can disturb the local structures of the imidazolium rings of [BMIM]+ and [HMIM]+. The pressure-induced phase transition of pure 1-butyl-3-methylimidazolium bromide ([BMIM]Br) is observed at a pressure of 0.4 GPa. Pressure-enhanced [BMIM]Br-PEO interactions may assist PEO in dividing [BMIM]Br clusters to hinder the aggregation of [BMIM]Br under high pressures. The C–H absorptions of pure 1-hexyl-3-methylimidazolium bromide [HMIM]Br do not show band narrowing under high pressures, as observed for pure [BMIM]Br. The band narrowing of C–H peaks is observed at 1.5 GPa for the [HMIM]Br-PEO mixture containing 80 wt% of [HMIM]Br. The presence of PEO may reorganize [HMIM]Br clusters into a semi-crystalline network under high pressures. The differences in aggregation states for ambient-pressure phase and high-pressure phase may suggest the potential of [HMIM]Br-PEO (M.W.~900,000) for serving as optical or electronic switches.

scholarly journals Pressure-Dependent Clustering in Ionic-Liquid-Poly (Vinylidene Fluoride) Mixtures: An Infrared Spectroscopic Study

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2099
Author(s):  
Teng-Hui Wang ◽  
Wei-Xiang Wang ◽  
Hai-Chou Chang
Keyword(s):  
High Pressure ◽  
High Pressures ◽  
Vinylidene Fluoride ◽  
Ambient Pressure ◽  
Infrared Spectroscopic Study ◽  
Research Attention ◽  
Nanoscale Structures ◽  
Local Structures ◽  
Poly Vinylidene Fluoride ◽  
Hydrogen Bonded

The nanostructures of ionic liquids (ILs) have been the focus of considerable research attention in recent years. Nevertheless, the nanoscale structures of ILs in the presence of polymers have not been described in detail at present. In this study, nanostructures of ILs disturbed by poly(vinylidene fluoride) (PVdF) were investigated via high-pressure infrared spectra. For 1-(2-hydroxyethyl)-3-methylimidazolium bis(trifluoromethanesulfonyl)imide ([HEMIm][TFSI])-PVdF mixtures, non-monotonic frequency shifts of the C4,5-H vibrations upon dilution were observed under ambient pressure. The experimental results suggest the presence of microheterogeneity in the [HEMIm][TFSI] systems. Upon compression, PVdF further influenced the local structure of C4,5–H via pressure-enhanced IL–PVdF interactions; however, the local structures of C2–H and hydrogen-bonded O–H were not affected by PVdF under high pressures. For choline [TFSI]–PVdF mixtures, PVdF may disturb the local structures of hydrogen-bonded O–H. In the absence of the C4,5–H⋯anion and C2–H⋯anion in choline [TFSI]–PVdF mixtures, the O–H group becomes a favorable moiety for pressure-enhanced IL–PVdF interactions. Our results indicate the potential of high-pressure application for designing pressure-dependent electronic switches based on the possible changes in the microheterogeneity and electrical conductivity in IL-PVdF systems under various pressures.

Density and Viscosity Estimation of 1-hexyl-3-methyl Imidazolium Based Ionic Liquids with [BF4] and [PF6] Anions at High Pressures

2011 ◽  
Vol 11 (13) ◽  
pp. 2452-2455 ◽  
Author(s):  
A. Muhammad ◽  
M.I. Abdul Mutalib ◽  
T. Murugesan ◽  
Z. Man ◽  
A. Bustam
Keyword(s):  
Ionic Liquids ◽  
High Pressures

Conformational preferences of two imidazolium-based ionic liquids at high pressures

2011 ◽  
Vol 511 (4-6) ◽  
pp. 241-246 ◽  
Author(s):  
Takahiro Takekiyo ◽  
Yusuke Imai ◽  
Naohiro Hatano ◽  
Hiroshi Abe ◽  
Yukihiro Yoshimura
Keyword(s):  
Ionic Liquids ◽  
High Pressures ◽  
Conformational Preferences

scholarly journals Towards the Equation of State for Neutral (C2H4), Polar (H2O), and Ionic ([bmim][BF4], [bmim][PF6], [pmmim][Tf2N]) Liquids

2014 ◽  
Vol 2014 ◽  
pp. 1-15 ◽  
Author(s):  
Vitaly B. Rogankov ◽  
Valeriy I. Levchenko
Keyword(s):  
Experimental Data ◽  
Ionic Liquids ◽  
Equation Of State ◽  
High Pressures ◽  
Strong Dependence ◽  
Fluid Equation ◽  
Lattice Fluid ◽  
Wide Range ◽  
Derived Properties ◽  
Vapor Liquid

Despite considerable effort of experimentalists no reliable vapor-liquid coexistence at very small pressures and liquid-solid coexistence at high pressures have been until now observed in the working range of temperature 290<T/K<350 for ionic liquids. The measurements of high-pressure properties in low-temperature stable liquid are relatively scarce while the strong influence of their consistency on the phase equilibrium prediction is obvious. In this work we discuss the applicability of fluctuational-thermodynamic methodology and respective equation of state to correlate the properties of any (neutral, polar, ionic) liquids since our ultimate goal is the simple reference predictive model to describe vapor-liquid, liquid-liquid, and liquid-solid equilibria of mixtures containing above components. It is shown that the inconsistencies among existing volumetric measurements and the strong dependence of the mechanical and, especially, caloric derived properties on the shape of the functions chosen to fit the experimental data can be resolved in the framework of fluctuational-thermodynamic equation of state. To illustrate its results the comparison with the known experimental data for [bmim][BF4] and [bmim][PF6] as well as with the lattice-fluid equation of state and the methodology of thermodynamic integration is represented. It corroborates the thermodynamic consistency of predictions and excellent correlation of derived properties over the wide range of pressures 0<P/MPa<200.

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