High-Accuracy Vapor Pressure Data of the Extended [CnC1im][Ntf2] Ionic Liquid Series: Trend Changes and Structural Shifts

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• 作者：Marisa A. A. Rocha ; Carlos F. R. A. C. Lima ; Li虂gia R. Gomes ; Bernd Schro虉der ; Joa虄o A. P. Coutinho ; Isabel M. Marrucho ; Jose虂 M. S. S. Esperanc抬a ; Lui虂s P. N. Rebelo ; Karina Shimizu ; Jose虂 N. Canongia Lopes ; Lui虂s M. N. B. F. Santos
• 刊名：Journal of Physical Chemistry B
• 出版年：2011
• 出版时间：September 22, 2011
• 年：2011
• 卷：115
• 期：37
• 页码：10919-10926
• 全文大小：977K
• 年卷期：v.115,no.37(September 22, 2011)
• ISSN：1520-5207

文摘

For the first time, two distinct trends are clearly evidenced for the enthalpies and entropies of vaporization along the [C_nmim][Ntf₂] ILs series. The trend shifts observed for 螖_{class="stack">l}^{class="stack">g}H_{class="stack">m}^{class="stack">o} and 螖_{class="stack">l}^{class="stack">g}S_{class="stack">m}^{class="stack">o}, which occur at [C₆mim][Ntf₂], are related to structural modifications. The thermodynamic results reported in the present article constitute the first quantitative experimental evidence of the structural percolation phenomenon and make a significant contribution to better understanding of the relationship among cohesive energies, volatilities, and liquid structures of ionic liquids. A new Knudsen effusion apparatus, combined with a quartz crystal microbalance, was used for the high-accuracy volatility study of the 1-alkyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide series ([C_nmim][Ntf₂], where n = 2, 3, 4, 5, 6, 7, 8, 10, 12). Vapor pressures in the (450鈥?00) K temperature range were measured, and the molar standard enthalpies, entropies, and Gibbs energies of vaporization were derived. The thermodynamic parameters of vaporization were reported, along with molecular dynamic simulations of the liquid phase structure, allowing the establishment of a link between the thermodynamic properties and the percolation phenomenon in ILs.