Behera Kamalakanta, Pandey Mrituanjay D, Porel Mintu, Pandey Siddharth
Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India.
J Chem Phys. 2007 Nov 14;127(18):184501. doi: 10.1063/1.2785178.
Modification of important physicochemical properties of aqueous surfactant solutions can be achieved by addition of environmentally benign room temperature ionic liquids (ILs). While low aqueous solubility of "hydrophobic" ILs limits the amount of IL that may be added to achieve desired changes in the physicochemical properties, hydrophilic ILs do not have such restrictions associated to them. Alterations in the key physicochemical properties of aqueous solutions of a common nonionic surfactant Triton X-100 (TX100) on addition of up to 30 wt % hydrophilic IL 1-butyl-3-methylimidazolium tetrafluoroborate ([bmim][BF4]) are reported. The presence of micellar aggregates in as high as 30 wt % [bmim][BF4]-added aqueous TX100 solutions is established by dynamic light scattering and fluorescence probe behavior. Increasing the concentration of [bmim][BF4] results in decrease in average micellar size and aggregation number and increase in critical micelle concentration, indicating an overall unfavorable aggregation process. Increase in the dipolarity and the microfluidity of the probe cybotactic region within the palisade layer of the micellar phase upon [bmim][BF4] addition implies increased water penetration and the possibility of TX100-[bmim][BF4] interactions. While the changes in some of the physicochemical properties indicate the role of [bmim][BF4] to be similar to a cosurfactant, the IL acts like a cosolvent as far as changes in other properties are concerned. Effectiveness of IL [bmim][BF4] in modifying physicochemical properties of aqueous TX100 is demonstrated.
通过添加环境友好型室温离子液体（ILs），可以实现对水性表面活性剂溶液重要物理化学性质的改性。虽然“疏水”离子液体在水中的低溶解度限制了为实现所需物理化学性质变化而可添加的离子液体量，但亲水性离子液体不存在此类限制。本文报道了在添加高达30 wt%的亲水性离子液体1-丁基-3-甲基咪唑四氟硼酸盐（[bmim][BF4]）时，常见非离子表面活性剂 Triton X-100（TX100）水溶液关键物理化学性质的变化。通过动态光散射和荧光探针行为确定了在添加高达30 wt% [bmim][BF4]的TX100水溶液中存在胶束聚集体。增加[bmim][BF4]的浓度会导致平均胶束尺寸和聚集数减小，临界胶束浓度增加，表明整体聚集过程不利。添加[bmim][BF4]后，胶束相栅栏层内探针环丁烷区域的偶极矩和微流动性增加，这意味着水的渗透增加以及TX100与[bmim][BF4]相互作用的可能性增加。虽然一些物理化学性质的变化表明[bmim][BF4]的作用类似于助表面活性剂，但就其他性质的变化而言，该离子液体的作用类似于助溶剂。证明了离子液体[bmim][BF4]在改性TX100水溶液物理化学性质方面的有效性。
