Mezger Markus, Roth Roland, Schröder Heiko, Reichert Peter, Pontoni Diego, Reichert Harald
Institute of Physics, Johannes Gutenberg University Mainz, 55128 Mainz, Germany.
Institute for Theoretical Physics, Eberhard Karls Universität Tübingen, 72076 Tübingen, Germany.
J Chem Phys. 2015 Apr 28;142(16):164707. doi: 10.1063/1.4918742.
The influence of the polar, aprotic solvent propylene carbonate on the interfacial structure of the ionic liquid (IL) 1-butyl-1-methylpyrrolidinium tris(pentafluoroethyl)trifluorophosphate on sapphire was investigated by high-energy x-ray reflectivity. Experiments at solvent concentrations between 17 mol. % and 83 mol. % bridge the gap between diluted electrolytes described by the classical Gouy-Chapman theory and pure ionic liquids. Analysis of our experimental data revealed interfacial profiles comprised of alternating anion and cation enriched regions decaying gradually into the bulk liquid. With increasing solvent concentration, we observed a decrease in correlation length of the interfacial layering structure. At high ion concentrations, solvent molecules were found to accumulate laterally within the layers. By separating like-charged ions, they reduce their Coulomb repulsion. The results are compared with the bulk structure of IL/solvent blends probed by x-ray scattering and predictions from fundamental fluid theory.
通过高能X射线反射率研究了极性非质子溶剂碳酸丙烯酯对离子液体1-丁基-1-甲基吡咯烷鎓三（五氟乙基）三氟磷酸盐在蓝宝石上的界面结构的影响。在17摩尔％至83摩尔％的溶剂浓度下进行的实验填补了经典 Gouy-Chapman 理论描述的稀释电解质与纯离子液体之间的空白。对我们实验数据的分析揭示了由交替的阴离子和阳离子富集区域组成的界面轮廓，这些区域逐渐衰减到本体液体中。随着溶剂浓度的增加，我们观察到界面分层结构的相关长度减小。在高离子浓度下，发现溶剂分子在层内横向积累。通过分离相同电荷的离子，它们减少了库仑排斥力。将结果与通过X射线散射探测的离子液体/溶剂混合物的本体结构以及基本流体理论的预测进行了比较。
