Kinetic Effect on Pressure-Induced Phase Transitions of Room Temperature Ionic Liquid, 1-Ethyl-3-methylimidazolium Trifluoromethanesulfonate

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• 作者：Haining Li ; Zheng Wang ; Liucheng Chen ; Jie Wu ; Haijun Huang ; Kun Yang ; Yongqiang Wang ; Lei Su ; Guoqiang Yang
• 刊名：Journal of Physical Chemistry B
• 出版年：2015
• 出版时间：November 5, 2015
• 年：2015
• 卷：119
• 期：44
• 页码：14245-14251
• 全文大小：463K
• ISSN：1520-5207

文摘

Room temperature ionic liquids (RTILs) have intriguing high-pressure phase behavior, and investigation of how pressure affects phase transitions of RTILs might yield interesting results. We here present kinetically driven phase transitions of 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][CF₃SO₃]) at different rates of 鈭?.3 and 鈭?.2 GPa/h up to 鈭? GPa. Two crystalline phases formed at 鈭?.3 and 鈭?.7 GPa with increasing pressure at lower compression rate of 鈭?.3 GPa/h; however, the amorphous phase solidified with superpressurized glass above 鈭?.3 GPa at higher compression rate of 鈭?.2 GPa/h. Notably, crystal polymorphism is discussed in view of the conformational isomerism of [Emim]⁺ cation and an unknown cation conformer is observed. These facts indicate that kinetic effect on pressure-induced phase transitions of [Emim][CF₃SO₃] might be dependent on compression rate, which needs to be considered as a non-negligible factor for phase transitions of RTILs under high pressure.