Chemistry Department, Faculty of Science, Kuwait University, P.O. Box 5969, Safat 13060, Kuwait.
J Colloid Interface Sci. 2013 Mar 1;393:210-8. doi: 10.1016/j.jcis.2012.10.071. Epub 2012 Nov 8.
The structure of solubilized water in water-in-n-heptane aggregates stabilized by mixtures of single- and double-tail quaternary ammonium surfactants, namely didodecyldimethylammonium chloride/dodecyltrimethylammonium chloride (DDAC/DTAC) or didodecyldimethylammonium bromide/dodecyltrimethylammonium bromide (DDAB/DTAB) was studied by two noninvasive techniques, (1)H NMR and FT-IR. In the former, the chemical shift data, δ(obs), were used to calculate the so-called deuterium/protium fractionation factor, φ(M), of the aggregate-solubilized water and were found to be unity. In the FT-IR study, upon increasing water/surfactant molar ratio, W, the frequency, ν(OD), of the HOD species decreases, while its full width at half height and its area increase. The results obtained from both techniques indicate that the water appears to be present as a single nano-phase and the structure varies continuously as a result of increasing W. In addition, the effect of changing the counter-ion (Br(-) or Cl(-)) on (1)H NMR and FT-IR results was investigated. In spite of the known difference in the dissociation of these counter-ions from micellar aggregates, this was found not to affect the state of solubilized water. This report gives further insight into the contradictory scientific debates on the structure of water in the polar nano-cores of microemulsions.
由单链和双链季铵盐表面活性剂（即二癸基二甲基氯化铵/十二烷基三甲基氯化铵（DDAC/DTAC）或二癸基二甲基溴化铵/十二烷基三甲基溴化铵（DDAB/DTAB）稳定的水包正庚烷胶束中增溶水的结构通过两种非侵入性技术，即（1）H NMR 和 FT-IR 进行了研究。在前者中，化学位移数据δ（obs）用于计算胶束增溶水中所谓的氘/质子分馏因子φ（M），并发现其为 1。在 FT-IR 研究中，随着水/表面活性剂摩尔比 W 的增加，HOD 物种的频率ν（OD）降低，而其半高全宽和面积增加。这两种技术的结果表明，水似乎以单一纳米相存在，并且由于 W 的增加，结构连续变化。此外，还研究了改变反离子（Br（-）或 Cl（-））对（1）H NMR 和 FT-IR 结果的影响。尽管已知这些反离子从胶束中的离解存在差异，但发现这并不影响增溶水的状态。本报告进一步深入了解了关于微乳液极性纳米核中水中结构的有争议的科学争论。
