Thermal properties of imidazolium ionic liquids

Ngo, Helen L.; LeCompte, Karen A.; Hargens, Liesl; McEwen, Alan B.

doi:10.1016/s0040-6031(00)00373-7

Cited by 987 publications

(706 citation statements)

References 13 publications

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“…Nearly all interaction parameters of the dicationic ionic liquids, C 4 (mim) 2 -NTf 2 and C 9 (mim) 2 -NTf 2 (10), are similar to those of the corresponding monomer-type ionic liquids, 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide. This is also observed for the pyrrolidinium dication, C 9 (mpy) 2 -NTf 2 (35), as it differs from the monomer-type analogue (1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide). This indicates that the well-known and highly useful solvation properties of traditional RTILs are very similar a The r ) interaction via nonbonding and π-electrons, s ) dipolarity/polarizability, a ) hydrogen bond basicity, b ) hydrogen bond acidity, l ) dispersion forces, n ) number of probe molecules subjected to multiple linear regression analysis, R 2 ) statistical correlation coefficient, F ) Fisher coefficient.…”

Section: High Stability Geminal Dicationic Ionic Liquidsmentioning

confidence: 68%

“…Ngo et al have previously reported the melting points for 1-ethyl-3-methylimidazolium bromide to be 79°C, whereas the melting point for 1-ethyl-2,3-dimethylimidazolium bromide was found to be 141°C, a difference of nearly 62°C. 35 While the methyl group on the two position of the imidazolium ring has little effect on the surface tension and density of the geminal dicationic ionic liquids, it is seen to have a profound effect on their melting points, moreso for the dicationic ionic liquids than for the traditional 1-alkyl-3-methylimidazolium ionic liquids.…”

Section: High Stability Geminal Dicationic Ionic Liquidsmentioning

confidence: 99%

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Structure and Properties of High Stability Geminal Dicationic Ionic Liquids

et al. 2004

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Thirty-nine geminal dicationic ILs were synthesized and characterized in terms of their surface tensions, densities, melting points, refractive indices, viscosities, and miscibilities with a polar and nonpolar solvent. Two imidazolium or pyrrolidinium cations were joined via different length hydrocarbon linkage chains (from 3 to 12 carbons long). The various geminal dications were paired with up to four different anions. The effect of the dication type, linkage chain, alkyl substituents, and anion type on the physicochemical properties of these compounds was examined. Among the more interesting findings for this class of compounds was that their liquid and thermal stability ranges generally exceeded those of the more conventional, better known ILs. Indeed, this range was from −4 to >400 °C for one of the pyrrolidinium-based geminal dicationic liquids. Xray crystallography of the smaller solid ionic compounds indicated that there may be a correlation between the configurational degrees of freedom of the ILs and their melting points/glass transition temperatures. In one case, the crystal structure showed that a dicationic moiety had three distinct conformations in an asymmetric unit cell. The solvation properties of the geminal dicationic ILs tend to be similar to those of their monocationic analogues. KeywordsCrystal structure, glass transition, hydrocarbons, liquids, melting, negative ions, refractive index, solubility, solvents, surface tension, thermodynamic stability, viscosity, x ray crystallography, pyrrolidinium cations Abstract: Thirty-nine geminal dicationic ILs were synthesized and characterized in terms of their surface tensions, densities, melting points, refractive indices, viscosities, and miscibilities with a polar and nonpolar solvent. Two imidazolium or pyrrolidinium cations were joined via different length hydrocarbon linkage chains (from 3 to 12 carbons long). The various geminal dications were paired with up to four different anions. The effect of the dication type, linkage chain, alkyl substituents, and anion type on the physicochemical properties of these compounds was examined. Among the more interesting findings for this class of compounds was that their liquid and thermal stability ranges generally exceeded those of the more conventional, better known ILs. Indeed, this range was from -4 to >400°C for one of the pyrrolidiniumbased geminal dicationic liquids. X-ray crystallography of the smaller solid ionic compounds indicated that there may be a correlation between the configurational degrees of freedom of the ILs and their melting points/glass transition temperatures. In one case, the crystal structure showed that a dicationic moiety had three distinct conformations in an asymmetric unit cell. The solvation properties of the geminal dicationic ILs tend to be similar to those of their monocationic analogues.

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Section: High Stability Geminal Dicationic Ionic Liquidsmentioning

confidence: 68%

Section: High Stability Geminal Dicationic Ionic Liquidsmentioning

confidence: 99%

Structure and Properties of High Stability Geminal Dicationic Ionic Liquids

et al. 2004

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“…The enhanced thermal stability of imidazolium surfactants as compared with the alkylammonium halides has been reported to be due to the delocalization of the positive charge over the imidazole ring [22] and [23]. Similarly, if the charge delocalization is increased by fusing a benzene ring to imidazole (as in the case of benzimidazole), one might expect further enhanced thermal stability.…”

Section: Morphology Of Polymer-clay Nanocompositesmentioning

confidence: 99%

Benzimidazolium surfactants for modification of clays for use with styrenic polymers

Costache

Heidecker

Manias

et al. 2007

Polymer Degradation and Stability

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Abstract:Nanocomposites of polystyrene (PS), acrylonitrile-butadiene-styrene copolymer (ABS) and high impact polystyrene (HIPS) were prepared with two new homologous benzimidazolium surfactants used as organic modifications for the clays. The morphology of the polymer/clay hybrids was evaluated by powder X-ray diffraction (XRD) and transmission electron microscopy (TEM), showing good overall dispersion of the clay. The thermal stability of the polymer/clay nanocomposites was enhanced, as evaluated by thermogravimetric analysis. From cone calorimetric measurements, the peak heat release rate of the nanocomposites was decreased by about the same amount as seen for other organically-modified, commercially available clays.

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“…An appropriate estimation of this property is a key factor in many engineering applications, including lubrication [17]. Despite the fact that a significant number of works have been focused on the study of thermal degradation of ILs [18][19][20][21][22][23][24][25], only a few of them have used phosphonium based ILs [13,15,26]. In addition, thermal stability is often misleadingly reported to extend up to temperatures of more than 400 ºC.…”

Section: Introductionmentioning

confidence: 99%

Isoconversional kinetic analysis applied to five phosphonium cation-based ionic liquids

et al. 2017

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Thermal degradation of five phosphonium cation-based ionic liquids ([P 66614 outperforming the other ones in both pyrolytic and oxidising conditions. Although the thermal degradation mechanism is affected by atmospheric conditions, the degradation trend remains practically constant. As the dynamic methodology usually overestimates the long-term thermal stability, an isoconversional methodology is better for predicting the long-term thermal stability of these ionic liquids in order to be used as base oil or additive in lubricants formulation. Finally, the model-free methodology can predict at lower costs the ILs performance in isothermal conditions. Highlights• Weakly coordinating anions provoke good thermal stability of ILs.• • Isoconversional methods are better than dynamic ones for long-term thermal studies.• Activation energy behavior at low conversions is related to a single reaction.• Model-free methodology can predict the ILs performance in isothermal conditions.

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Thermal properties of imidazolium ionic liquids

Cited by 987 publications

References 13 publications

Structure and Properties of High Stability Geminal Dicationic Ionic Liquids

Structure and Properties of High Stability Geminal Dicationic Ionic Liquids

Benzimidazolium surfactants for modification of clays for use with styrenic polymers

Isoconversional kinetic analysis applied to five phosphonium cation-based ionic liquids

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