Centro de Investigação em Química, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, R. Campo Alegre 687, P-4169-007 Porto, Portugal.
J Phys Chem B. 2011 Sep 22;115(37):10919-26. doi: 10.1021/jp2049316. Epub 2011 Aug 25.
For the first time, two distinct trends are clearly evidenced for the enthalpies and entropies of vaporization along the [Cnmim][Ntf2] ILs series. The trend shifts observed for Δ(l)(g)H(m)(o) and Δ(l)(g)S(m)(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 ([Cnmim][Ntf2], where n = 2, 3, 4, 5, 6, 7, 8, 10, 12). Vapor pressures in the (450–500) 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.
首次在 [Cnmim][Ntf2] ILs 系列中清楚地证明了蒸发焓和熵的两个明显趋势。在 [C6mim][Ntf2] 处观察到的 Δ(l)(g)H(m)(o) 和 Δ(l)(g)S(m)(o) 趋势变化与结构修饰有关。本文报道的热力学结果构成了结构渗透现象的第一个定量实验证据，对更好地理解离子液体的内聚能、挥发性和液体结构之间的关系做出了重要贡献。一种新的克努森扩散装置与石英晶体微天平相结合，用于高精度研究 1-烷基-3-甲基咪唑𬭩双（三氟甲烷磺酰基）亚胺系列([Cnmim][Ntf2]，其中 n = 2,3,4,5,6,7,8,10,12)的挥发性。在 (450-500) K 的温度范围内测量了蒸气压，并推导了蒸发的摩尔标准焓、熵和吉布斯自由能。报道了蒸发的热力学参数，并对液相结构进行了分子动力学模拟，从而在离子液体的热力学性质和渗透现象之间建立了联系。
