Thermodynamics, Structure, and Dynamics in Room Temperature Ionic Liquids: The Case of 1-Butyl-3-methyl Imidazolium Hexafluorophosphate ([bmim][PF6])

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• 作者：Alessandro Triolo ; Andrea Mandanici ; Olga Russina ; Virginia Rodriguez-Mora ; Maria Cutroni ; Christopher Hardacre ; Mark Nieuwenhuyzen ; Hans-Jurgen Bleif ; Lukas Keller ; Miguel Angel Ramos
• 刊名：Journal of Physical Chemistry B
• 出版年：2006
• 出版时间：October 26, 2006
• 年：2006
• 卷：110
• 期：42
• 页码：21357 - 21364
• 全文大小：281K
• 年卷期：v.110,no.42(October 26, 2006)
• ISSN：1520-5207

文摘

A detailed investigation of the phase diagram of 1-butyl-3-methyl imidazolium hexafluorophosphate([bmim][PF₆]) is presented on the basis of a wide set of experimental data accessing thermodynamic, structural,and dynamical properties of this important room temperature ionic liquid (RTIL). The combination of quasiadiabatic, continuous calorimetry, wide angle neutron and X-ray diffraction, and quasi elastic neutron scatteringallows the exploration of many novel features of this material. Thermodynamic and microscopic structuralinformation is derived on both glassy and crystalline states and compared with results that recently appearedin the literature allowing direct information to be obtained on the existence of two crystalline phases thatwere not previously characterized and confirming the view that RTILs show a substantial degree of order(even in their amorphous states), which resembles the crystalline order. We highlight a strong connectionbetween structure and dynamics, showing the existence of three temperature ranges in the glassy state acrosswhich both the spatial correlation and the dynamics change. The complex crystalline polymorphism in[bmim][PF₆] also is investigated; we compare our findings with the corresponding findings for similar RTILs.These results provide a strong experimental basis for the exploration of the features of the phase diagram ofRTILs and for the further study of longer alkyl chain salts.