The Experts below are selected from a list of 186435 Experts worldwide ranked by ideXlab platform

Ulrich S Schubert - One of the best experts on this subject based on the ideXlab platform.

  • cellulose molecular properties in 1 alkyl 3 methylimidazolium based ionic liquid mixtures with pyridine
    Carbohydrate Polymers, 2010
    Co-Authors: Jurgen Vitz, N P Yevlampieva, Evgeny Rjumtsev, Ulrich S Schubert
    Abstract:

    A study of the viscometric and dynamooptical (flow birefringence) properties of cellulose samples in mixtures of 1-Alkyl-3-Methylimidazolium-based ionic liquids with pyridine was carried out. It was established that the mixtures provide stable molecular dispersed cellulose solutions which are suitable for the determination of the characteristics of the dissolved macromolecules. The viscous and dynamooptical properties of cellulose in ionic liquid/pyridine mixtures, cadoxen (CdO/ethylenediamine), and in cadoxen/water at low solute concentrations were compared, and the behavior of cellulose in these solvents was discussed. It was found that the values of the refractive index of 1-alkyl-3methylimidazolium-based ionic liquid/pyridine mixtures are close to the refractive index of cellulose in their media. The extremely low refractive index increment (|dn/dc| = (0.004 ± 0.001) cm3 g−1) for cellulose in 1-ethyl-3-methylimidazolium diethylphosphate and pyridine ([EMIM]Et2PO4/pyridine (1:1)) allowed to confirm that the cellulose monomer unit is not optically isotropic and is characterized by a small in value and positive in sign anisotropy of polarizability (� a = +1.0 × 10 −25 cm 3

  • Cellulose molecular properties in 1-Alkyl-3-Methylimidazolium-based ionic liquid mixtures with pyridine
    Carbohydrate Polymers, 2010
    Co-Authors: Jurgen Vitz, N P Yevlampieva, Evgeny Rjumtsev, Ulrich S Schubert
    Abstract:

    A study of the viscometric and dynamooptical (flow birefringence) properties of cellulose samples in mixtures of 1-Alkyl-3-Methylimidazolium-based ionic liquids with pyridine was carried out. It was established that the mixtures provide stable molecular dispersed cellulose solutions which are suitable for the determination of the characteristics of the dissolved macromolecules. The viscous and dynamooptical properties of cellulose in ionic liquid/pyridine mixtures, cadoxen (CdO/ethylenediamine), and in cadoxen/water at low solute concentrations were compared, and the behavior of cellulose in these solvents was discussed. It was found that the values of the refractive index of 1-alkyl-3methylimidazolium-based ionic liquid/pyridine mixtures are close to the refractive index of cellulose in their media. The extremely low refractive index increment (|dn/dc| = (0.004 ± 0.001) cm3 g−1) for cellulose in 1-ethyl-3-methylimidazolium diethylphosphate and pyridine ([EMIM]Et2PO4/pyridine (1:1)) allowed to confirm that the cellulose monomer unit is not optically isotropic and is characterized by a small in value and positive in sign anisotropy of polarizability (� a = +1.0 × 10 −25 cm 3

  • homogeneous tritylation of cellulose in 1 butyl 3 methylimidazolium chloride
    Macromolecular Bioscience, 2007
    Co-Authors: Tina Erdmenger, Claudia Haensch, Richard Hoogenboom, Ulrich S Schubert
    Abstract:

    1-Alkyl-3-Methylimidazolium-based ionic liquids, having chloride as a counter ion, were studied for cellulose solubility; and the influence of different alkyl chain lengths was also investigated. The alkyl chain length was incrementally varied from ethyl to decyl to determine structure-dissolution properties; a distinct odd-even effect was observed for short chain lengths. In addition, the tritylation of cellulose was performed in 1-butyl-3-methylimidazolium chloride using pyridine as base. The influences of reaction time and the ratio of trityl chloride per cellulose monomer unit on the degree of substitution were investigated in detail by elemental analysis and 1H NMR spectroscopy. A DS of around 1 was obtained after 3 h reaction time using a six fold excess of trityl chloride.

Kenneth R. Seddon - One of the best experts on this subject based on the ideXlab platform.

Marek Kosmulski - One of the best experts on this subject based on the ideXlab platform.

  • Permittivities of 1-Alkyl-3-Methylimidazolium Tetrafluoroborates and Hexafluorophosphates
    Croatica Chemica Acta, 2007
    Co-Authors: Marek Kosmulski, Krystyna Marczewska-boczkowska, Pawel Zukowski, Jan Subocz, Czesław Saneluta
    Abstract:

    Permittivities of 1-Alkyl-3-Methylimidazolium tetrafluoroborates, hexafluorophosphates, and tetrafluoroborate-chloride mixtures (alkyl = butyl, hexyl, octyl or decyl) were determined from the capacitance of a specially designed capacitor, which was measured as the function of frequency over the range from 0.001 Hz to 5 MHz. The measurement setup was tested against molecular liquids. Water and methanol gave relatively stable results, which comply with the permittivities known from the literature over a frequency range from 30 kHz to 3 MHz. The apparent permittivity measured at lower frequencies was highly overestimated. With low-temperature ionic liquids, the plateau in the apparent permittivity as the function of frequency was narrower, and it was observed between 1 and 3 MHz. Yet, the apparent permittivities in the plateau region are still overestimated, at least for l-butyl-3-methylimidazolium salts.

  • Low-temperature ionic liquids immobilized in porous alumina.
    Journal of Colloid and Interface Science, 2005
    Co-Authors: Marek Kosmulski, Czesław Saneluta, Mikolaj Szafran, Krystyna Marczewska-boczkowska
    Abstract:

    The pores in an aluminum oxide matrix can be completely filled with 1-Alkyl-3-Methylimidazolium tetrafluoroborates, hexafluorophosphates, triflates, and bis(trifluoromethylsulfonyl)imides. This possibility can be utilized to produce solid electrolytes for batteries and fuel cells.

  • thermal stability of low temperature ionic liquids revisited
    Thermochimica Acta, 2004
    Co-Authors: Marek Kosmulski, Jan Gustafsson, Jarl B Rosenholm
    Abstract:

    Abstract The range of thermal stability of low temperature ionic liquids published in the literature (often >400 °C) is severely overrated. The decomposition temperature calculated from fast TGA scans in a protective atmosphere does not imply a long-term thermal stability below that temperature. Even at temperatures as low at 200 °C, 1-Alkyl-3-Methylimidazolium phosphates (alkyl = C4–C10) and 1-decyl-3-methylimidazolium triflate showed a slow, but appreciable mass loss. On the other hand, 1-butyl-3-methylimidazolium triflate was stable at 200 °C. The carbonization occurred in most studies salts irrespectively of the nature of the anion (hexafluorophosphate, triflate), but the salts with a shorter side chain (C4) did not show changes in their color after conditioning for 10 h at 200 °C in air. 1-Butyl-3-methylimidazolium triflate shows extremely good wettability against aluminum oxide and silver at elevated temperatures. Addition of silica (amorphous or quartz) accelerates the thermal decomposition of 1-Alkyl-3-Methylimidazolium phosphates and triflates at 200 °C, while the effect of other ceramic powders (titania, alumina) is less significant.

Johan Jacquemin - One of the best experts on this subject based on the ideXlab platform.

  • Isobaric and Isochoric Heat Capacities of Imidazolium-Based and Pyrrolidinium-Based Ionic Liquids as a Function of Temperature: Modeling of Isobaric Heat Capacity
    Industrial and engineering chemistry research, 2017
    Co-Authors: Edward Zorębski, Michał Zorębski, Marzena Dzida, Peter Goodrich, Johan Jacquemin
    Abstract:

    The isobaric and isochoric heat capacities of seven 1-Alkyl-3-Methylimidazolium bis(trifluoromethylsulfonyl)imides, two 1-alkyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imides, and two bis(1-Alkyl-3-Methylimidazolium) tetrathiocyanatocobaltates were determined at atmospheric pressure in the temperature range from 293.15 to 323.15 K. The isobaric heat capacities were determined by means of differential scanning calorimetry, whereas isochoric heat capacities were determined along with isothermal compressibilities indirectly by means of the acoustic method from the speed of sound and density measurements. Based on the experimental data, as expected, the isobaric heat capacity increases linearly with increasing alkyl chain length in the cation of 1-Alkyl-3-Methylimidazolium bis(trifluoromethylsulfonyl)imides and no odd and even carbon number effect is observed. After critical comparison of the obtained data with the available literature data, the most reliable values are recommended. It has been also shown that, although the COSMOthermX calculations underestimated the isobaric heat capacity values whatever the temperature and the ionic liquid structure, the approach used during this work may be applied to estimate physical properties of non-single-charged ions as well. Additionally, based on the speeds of sound the thermal conductivities were calculated using a modified Bridgman relation.

  • Ultrasonic Relaxation Study of 1-Alkyl-3-Methylimidazolium-Based Room-Temperature Ionic Liquids: Probing the Role of Alkyl Chain Length in the Cation
    The journal of physical chemistry. B, 2016
    Co-Authors: Michał Zorębski, Edward Zorębski, Marzena Dzida, Peter Goodrich, Justyna Skowronek, Sylwia Jężak, Johan Jacquemin
    Abstract:

    Ultrasound absorption spectra of four 1-Alkyl-3-Methylimidazolium bis(trifluoromethylsulfonyl)imides were determined as a function of the alkyl chain length on the cation from 1-propyl to 1-hexyl from 293.15 to 323.15 K at ambient pressure. Herein, the ultrasound absorption measurements were carried out using a standard pulse technique within a frequency range from 10 to 300 MHz. Additionally, the speed of sound, density, and viscosity have been measured. The presence of strong dissipative processes during the ultrasound wave propagation was found experimentally, i.e., relaxation processes in the megahertz range were observed for all compounds over the whole temperature range. The relaxation spectra (both relaxation amplitude and relaxation frequency) were shown to be dependent on the alkyl side chain length of the 1-Alkyl-3-Methylimidazolium ring. In most cases, a single-Debye model described the absorption spectra very well. However, a comparison of the determined spectra with the spectra of a few other...

Jurgen Vitz - One of the best experts on this subject based on the ideXlab platform.

  • cellulose molecular properties in 1 alkyl 3 methylimidazolium based ionic liquid mixtures with pyridine
    Carbohydrate Polymers, 2010
    Co-Authors: Jurgen Vitz, N P Yevlampieva, Evgeny Rjumtsev, Ulrich S Schubert
    Abstract:

    A study of the viscometric and dynamooptical (flow birefringence) properties of cellulose samples in mixtures of 1-Alkyl-3-Methylimidazolium-based ionic liquids with pyridine was carried out. It was established that the mixtures provide stable molecular dispersed cellulose solutions which are suitable for the determination of the characteristics of the dissolved macromolecules. The viscous and dynamooptical properties of cellulose in ionic liquid/pyridine mixtures, cadoxen (CdO/ethylenediamine), and in cadoxen/water at low solute concentrations were compared, and the behavior of cellulose in these solvents was discussed. It was found that the values of the refractive index of 1-alkyl-3methylimidazolium-based ionic liquid/pyridine mixtures are close to the refractive index of cellulose in their media. The extremely low refractive index increment (|dn/dc| = (0.004 ± 0.001) cm3 g−1) for cellulose in 1-ethyl-3-methylimidazolium diethylphosphate and pyridine ([EMIM]Et2PO4/pyridine (1:1)) allowed to confirm that the cellulose monomer unit is not optically isotropic and is characterized by a small in value and positive in sign anisotropy of polarizability (� a = +1.0 × 10 −25 cm 3

  • Cellulose molecular properties in 1-Alkyl-3-Methylimidazolium-based ionic liquid mixtures with pyridine
    Carbohydrate Polymers, 2010
    Co-Authors: Jurgen Vitz, N P Yevlampieva, Evgeny Rjumtsev, Ulrich S Schubert
    Abstract:

    A study of the viscometric and dynamooptical (flow birefringence) properties of cellulose samples in mixtures of 1-Alkyl-3-Methylimidazolium-based ionic liquids with pyridine was carried out. It was established that the mixtures provide stable molecular dispersed cellulose solutions which are suitable for the determination of the characteristics of the dissolved macromolecules. The viscous and dynamooptical properties of cellulose in ionic liquid/pyridine mixtures, cadoxen (CdO/ethylenediamine), and in cadoxen/water at low solute concentrations were compared, and the behavior of cellulose in these solvents was discussed. It was found that the values of the refractive index of 1-alkyl-3methylimidazolium-based ionic liquid/pyridine mixtures are close to the refractive index of cellulose in their media. The extremely low refractive index increment (|dn/dc| = (0.004 ± 0.001) cm3 g−1) for cellulose in 1-ethyl-3-methylimidazolium diethylphosphate and pyridine ([EMIM]Et2PO4/pyridine (1:1)) allowed to confirm that the cellulose monomer unit is not optically isotropic and is characterized by a small in value and positive in sign anisotropy of polarizability (� a = +1.0 × 10 −25 cm 3