Interactions of Silica Nanoparticles and Ionic Liquids Probed by High Pressure Vibrational Spectroscopy

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• 作者：Hai-Chou Chang ; Tzu-Chieh Hung ; Shu-Chieh Chang ; Jyh-Chiang Jiang ; Sheng Hsien Lin
• 刊名：Journal of Physical Chemistry C
• 出版年：2011
• 出版时间：June 23, 2011
• 年：2011
• 卷：115
• 期：24
• 页码：11962-11967
• 全文大小：832K
• 年卷期：v.115,no.24(June 23, 2011)
• ISSN：1932-7455

文摘

Gel-like ionic liquid/nanosilica mixtures have been prepared with the addition of 10 wt % nanosilica to 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (EMI⁺TFSA^{鈥?/sup>), but no changes in C鈥揌 spectral features of EMI+TFSA鈥?/sup> were observed in the presence of nanosilica under ambient pressure. As the gel-like mixture of EMI+TFSA鈥?/sup>/nanosilica was compressed, a new alkyl C鈥揌 band at ca. 3017 cm鈥? arose. This new spectral feature at ca. 3017 cm鈥? may be attributed to the structural reorganization of alkyl C鈥揌 groups induced by the interactions between ionic clusters and nanosilica. The imidazolium C鈥揌 bands display nonmonotonic shifts as the pressure is elevated. They blue shift slightly initially, but red shifts occur upon further increase of the pressure. The compression also leads to an increase in the relative intensity of the imidazolium C鈥揌 band at ca. 3105 cm鈥?. This observation suggests that some associated species are switched to the isolated form due to the presence of nanosilica under high pressures. In contrast to EMI+TFSA鈥?/sup>/nanosilica, the band frequencies and band shapes of 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide (BMI+TFSA鈥?/sup>)/nanosilica are similar to those of pure BMI+TFSA鈥?/sup>. These results indicate that the length of alkyl C鈥揌 groups plays a nonnegligible role in isolated-associated equilibrium.}