肺表面活性物质
反离子
吸附
化学
阳离子聚合
溴化铵
十二烷基硫酸钠
临界胶束浓度
胶束
离子
无机化学
朗缪尔吸附模型
分析化学(期刊)
化学工程
化学物理
物理化学
色谱法
有机化学
水溶液
工程类
生物化学
作者
Aswathi Vilangottunjalil,Jan Versluis,Huib J. Bakker
标识
DOI:10.1021/acs.jpclett.3c03377
摘要
We employed heterodyne-detected vibrational sum-frequency generation (HD-VSFG) spectroscopy to obtain a molecular-level understanding of the interaction between the anionic surfactant sodium dodecyl ammonium sulfate (SDS) and the cationic surfactant dodecyltrimethylammonium bromide (DTAB). We observed that these surfactants show a strong cooperative effect on their adsorption to the water–air interface. Even at bulk concentrations 1000 times lower than the critical micelle concentrations of SDS and DTAB, a nearly complete surface surfactant layer is observed when both surfactants are present. This strong enhancement of the surface concentrations of DS– and DTA+ can be quantitatively explained from the favorable Coulomb interaction of the oppositely charged headgroups of DS– and DTA+ and the electrostatic interactions with their counterions. The HD-VSFG results are complemented by a modified Langmuir adsorption model in which we include the free energy associated with the electrostatic interactions of the surfactant ions and their counterions.
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