Institute of Physical and Theoretical Chemistry, University of Regensburg, 93040 Regensburg, Germany.
J Colloid Interface Sci. 2011 Oct 15;362(2):423-9. doi: 10.1016/j.jcis.2011.06.059. Epub 2011 Jul 7.
In this work, we report on the phase behavior of 1-ethyl-3-methyl-imidazolium-ethylsulfate ([emim][etSO(4)])/limonene/polyethylene glycol tert-octylphenyl ether (Triton X-114 or TX-114) microemulsions as a function of ionic liquid (IL) content and temperature. Phase diagrams, conductivity measurements, and small angle X-ray scattering (SAXS) experiments will be presented. A hydrophilic IL, instead of water is used with the goal to enlarge the temperature range on which stable microemulsions can be formed. Indeed, the system shows remarkably large temperature stability, in particular down to -35 °C. We will emphasize on a comparison with a recently published work about microemulsions composed of [emim][etSO(4)], limonene, and Triton X-100 that to some extent are stable at temperatures well below the freezing point of water. The key parameter responsible for the difference in phase behavior, microstructure, and temperature stability is the average repeating number of ethylene oxide units in the surfactant head group, which is smaller for Triton X-114 compared to Triton X-100. Among the fundamental interest, how the amphiphilicity of the surfactant influences the phase diagram and phase behavior of IL-based microemulsions, the exchange of Triton X-100 by Triton X-114 results in one main advantage: along the experimental path the temperature where phase segregation occurs is significantly lowered leading to single phase microemulsions that exist at temperatures beneath 0 °C.
在这项工作中，我们报告了 1-乙基-3-甲基-咪唑𬭩乙基硫酸盐([emim][etSO(4)])/柠檬烯/聚乙二醇叔辛基苯基醚(Triton X-114 或 TX-114)微乳液的相行为作为离子液体(IL)含量和温度的函数。将介绍相图、电导率测量和小角 X 射线散射(SAXS)实验。使用亲水性 IL 代替水，目的是扩大可以形成稳定微乳液的温度范围。实际上，该系统显示出非常大的温度稳定性，特别是低至-35°C。我们将重点介绍与最近发表的关于由[emim][etSO(4)]、柠檬烯和 Triton X-100 组成的微乳液的工作进行比较，这些微乳液在一定程度上在远低于水冰点的温度下稳定。导致相行为、微结构和温度稳定性差异的关键参数是表面活性剂头基中乙氧化重复单元的平均重复数，Triton X-114 比 Triton X-100 小。在基础研究中，表面活性剂的两亲性如何影响基于 IL 的微乳液的相图和相行为，用 Triton X-114 交换 Triton X-100 有一个主要优点：沿着实验路径，相分离发生的温度显著降低，导致单相微乳液在 0°C 以下的温度下存在。
