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Nanomaterials 2019, 9(4), 620;

Pressure-Dependent Confinement Effect of Ionic Liquids in Porous Silica

Department of Chemistry, National Dong Hwa University, Shoufeng, Hualien 974, Taiwan
Author to whom correspondence should be addressed.
Received: 13 March 2019 / Revised: 9 April 2019 / Accepted: 10 April 2019 / Published: 16 April 2019
PDF [1407 KB, uploaded 16 April 2019]


The effect of confining ionic liquids (ILs) such as 1-ethyl-3-methylimidazolium tetrafluoroborate [C2C1Im][BF4] or 1-butyl-3-methylimidazolium tetrafluoroborate [C4C1Im][BF4] in silica matrices was investigated by high-pressure IR spectroscopy. The samples were prepared via the sol-gel method, and the pressure-dependent changes in the C–H absorption bands were investigated. No appreciable changes were observed in the spectral features when the ILs were confined in silica matrices under ambient pressure. That is, the infrared measurements obtained under ambient pressure were not sufficient to detect the interfacial interactions between the ILs and the porous silica. However, dramatic differences were observed in the spectral features of [C2C1Im][BF4] and [C4C1Im][BF4] in silica matrices under the conditions of high pressures. The surfaces of porous silica appeared to weaken the cation-anion interactions caused by pressure-enhanced interfacial IL-silica interactions. This confinement effect under high pressures was less obvious for [C4C1Im][BF4]. The size of the cations appeared to play a prominent role in the IL-silica systems. View Full-Text
Keywords: ionic liquid; IR spectroscopy; silica; high pressure ionic liquid; IR spectroscopy; silica; high pressure

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Wang, T.-H.; Lin, E.-Y.; Chang, H.-C. Pressure-Dependent Confinement Effect of Ionic Liquids in Porous Silica. Nanomaterials 2019, 9, 620.

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