Institute of Physical and Theoretical Chemistry, University of Regensburg, 93040 Regensburg, Germany.
J Colloid Interface Sci. 2010 Jul 15;347(2):227-32. doi: 10.1016/j.jcis.2010.03.031. Epub 2010 Mar 19.
The increasing number of publications reflects the still growing interest in nonaqueous microemulsions containing room-temperature ionic liquids. Recently, we characterized microemulsions composed of the room-temperature ionic liquid ethylammonium nitrate (EAN) as polar phase, dodecane as continuous phase and 1-hexadecyl-3-methyl imidazolium chloride ([C(16)mim][Cl]), an IL that exhibits surfactant properties, and decanol as cosurfactant at ambient temperature. We demonstrate here the high thermal stability of these microemulsions. Along an experimental path, no phase change could be observed visually within a temperature range between 30 degrees C and 150 degrees C. The microemulsions are characterized with quasi-elastic light scattering measurements at ambient temperature and temperature dependent small angle neutron scattering (SANS) experiments between 30 degrees C and 150 degrees C. DLS measurements at ambient temperature indicate a swelling of the formed structures with increasing amount of EAN up to a certain threshold. The SANS experiments were performed below this threshold. The data evaluation of such concentrated systems like microemulsions is possible with the "generalized indirect Fourier transformation" method (GIFT). We evaluated the small angle scattering data via the GIFT method, for comparison we also applied the model of Teubner and Strey (TS) which was often used to describe scattering curves of microemulsions. The GIFT method gives good fits throughout the experimental path, while the TS model gives relatively poor fits. Both, light scattering and SANS results are in agreement with the existence of EAN droplets stabilized by surfactant with dodecane as continuous phase along the whole investigated temperature range. Moreover, these results clearly demonstrate the possibility to formulate high temperature stable microemulsions with ionic liquids at ambient pressure.
越来越多的出版物反映了人们对含有室温离子液体的非水微乳液的兴趣仍在不断增长。最近，我们对由室温离子液体硝酸乙基铵（EAN）作为极性相、十二烷作为连续相和 1-十六烷基-3-甲基咪唑氯([C(16)mim][Cl])组成的微乳液进行了表征，后者是一种具有表面活性剂性质的离子液体，以及癸醇作为环境温度下的共乳化剂。我们在这里证明了这些微乳液具有很高的热稳定性。在实验过程中，在 30°C 至 150°C 的温度范围内，肉眼观察不到任何相变。在环境温度下用准弹性光散射测量和在 30°C 至 150°C 之间的温度依赖小角中子散射（SANS）实验对微乳液进行了表征。在环境温度下进行的 DLS 测量表明，随着 EAN 量的增加，形成的结构会发生肿胀，直到达到一定的阈值。SANS 实验是在低于这个阈值的情况下进行的。对于像微乳液这样的浓缩体系，可以使用“广义间接傅里叶变换”方法（GIFT）来评估小角度散射数据。我们通过 GIFT 方法评估了小角度散射数据，为了比较，我们还应用了 Teubner 和 Strey（TS）模型，该模型常用于描述微乳液的散射曲线。GIFT 方法在整个实验过程中给出了很好的拟合，而 TS 模型给出的拟合相对较差。光散射和 SANS 结果都与在整个研究温度范围内存在由十二烷稳定的 EAN 液滴的情况一致，表面活性剂作为连续相。此外，这些结果清楚地表明了在环境压力下用离子液体配制高温稳定的微乳液的可能性。
