We report a small angle X-ray scattering study on the liquid phase of a series of room temperature ionic liquids and their binary mixtures. The ionic liquids studied belong to the tri-alkyl-methyl-ammonium family with bis(trifluoromethanesulfonyl)amide as the anion and were studied as a function of alkyl chain length. These ionic liquids were found to exhibit marked nanoscale ordering in their isotropic liquid state as judged from the small angle X-ray scattering. The observed structural ordering is of supramolecular order and depends strongly on the length of the cation hydrophobic side chain. Moreover, the data can be analyzed on the basis of a disordered smectic A phase, consisting of strongly interdigitated bilayers that sequester the ionic liquid into polar and hydrophobic regions. These findings were also found to be consistent with density data of these molten salts. Additionally, we demonstrate that this experimentally observed nanostructuring can further be fine-tuned using binary mixtures.
我们报告了对一系列室温
离子液体及其二元混合物液相的小角 X 射线散射研究。所研究的
离子液体属于以双(
三氟甲烷磺酰)酰胺为阴离子的三烷基-甲基-
铵家族,并将其作为烷基链长的函数进行了研究。通过小角 X 射线散射,发现这些
离子液体在各向同性液体状态下表现出明显的纳米级有序性。观察到的结构有序是超分子有序,并与阳离子疏
水侧链的长度密切相关。此外,这些数据还可以在无序 Smectic A 相的基础上进行分析,该 A 相由强烈交错的双层膜组成,将
离子液体封闭在极性和疏
水区域。这些发现也与这些熔盐的密度数据相一致。此外,我们还证明了这种实验观察到的纳米结构可通过二元混合物进一步微调。