Please use this identifier to cite or link to this item: http://repositorio.unicamp.br/jspui/handle/REPOSIP/326069
Type: Artigo
Title: Comparing Two Tetraalkylammonium Ionic Liquids. Ii. Phase Transitions
Comparing two tetraalkylammonium ionic liquids. II. Phase transitions
Author: Lima, T. A.
Paschoal, V. H.
Faria, L. F. O.
Ribeiro, M. C. C.
Ferreira, F. F.
Costa, F. N.
Giles, C.
Abstract: Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl) imide, [N-1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl) imide, [N-1114][NTf2], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N-1114][NTf2] experiences glass transition at low temperature, whereas [N-1114][NTf2] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picture of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions. Published by AIP Publishing.
Phase transitions of the ionic liquids n-butyl-trimethylammonium bis(trifluoromethanesulfonyl) imide, [N-1114][NTf2], and methyl-tributylammonium bis(trifluoromethanesulfonyl) imide, [N-1114][NTf2], were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD) measurements, and Raman spectroscopy. XRD and Raman spectra were obtained as a function of temperature at atmospheric pressure, and also under high pressure at room temperature using a diamond anvil cell (DAC). [N-1114][NTf2] experiences glass transition at low temperature, whereas [N-1114][NTf2] crystallizes or not depending on the cooling rate. Both the ionic liquids exhibit glass transition under high pressure. XRD and low-frequency Raman spectra provide a consistent physical picture of structural ordering-disordering accompanying the thermal events of crystallization, glass transition, cold crystallization, pre-melting, and melting. Raman spectra in the high-frequency range of some specific cation and anion normal modes reveal conformational changes of the molecular structures along phase transitions.
Subject: Líquidos iônicos, Pressão atmosférica, Transição de fase
Country: Estados Unidos
Editor: AIP Publishing
Citation: Journal Of Chemical Physics. Amer Inst Physics, v. 144, p. , 2016.
Rights: fechado
Identifier DOI: 10.1063/1.4953415
Address: https://aip.scitation.org/doi/10.1063/1.4953415
Date Issue: 2016
Appears in Collections:IFGW - Artigos e Outros Documentos

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