A High-Pressure Study of the Effects of TiO2 Nanoparticles on the Structural Organization of Ionic Liquids
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- 作者：Hai-Chou Chang ; Shu-Chieh Chang ; Tzu-Chieh Hung ; Jyh-Chiang Jiang ; Jer-Lai Kuo ; Sheng Hsien Lin
- 刊名：Journal of Physical Chemistry C
- 出版年：2011
- 出版时间：December 8, 2011
- 年：2011
- 卷：115
- 期：48
- 页码：23778-23783
- 全文大小：865K
- 年卷期：v.115,no.48(December 8, 2011)
- ISSN：1932-7455
文摘
The local structures between nano-TiO2 and 1-ethyl-3-methylimidazolium trifluoromethanesulfonate (EMI+TFS鈥?/sup>) and 1-butyl-3-methylimidazolium trifluoromethanesulfonate (BMI+TFS鈥?/sup>) were investigated using high-pressure infrared spectroscopy. No significant changes in C鈥揌 spectral features of EMI+TFS鈥?/sup> were observed in the presence of nano-TiO2 under ambient pressure. As the EMI+TFS鈥?/sup>/nano-TiO2 mixture was compressed to 0.3 GPa, the imidazolium C鈥揌 absorptions became two sharp bands at 3108 and 3168 cm鈥?, respectively, and the alkyl C鈥揌 stretching absorption exhibits a new band at 3010 cm鈥? associated with a weaker band at 3028 cm鈥?. It appears that pressure stabilizes the isolated conformations due to pressure-enhanced imidazolium C鈥揌---nano-TiO2 interactions. Our results also reveal that alkyl C鈥揌 groups play non-negligible roles at the conditions of high pressures. The results of BMI+TFS鈥?/sup>/nano-TiO2 are remarkably different from what is revealed for EMI+TFS鈥?/sup>/nano-TiO2. The spectral features and band frequencies of BMI+TFS鈥?/sup>/nano-TiO2 are almost identical to those of pure BMI+TFS鈥?/sup> under various pressures. This study demonstrates that changes to the alkyl chain length of the cation could be made to control the order and strength of ionic liquid/nano-TiO2 interactions.