AMOLF, Science Park 104, 1098 XGAmsterdam, The Netherlands.
Condensed Matter and Statistical Physics Centre, International Centre for Theoretical Physics, Strada Costiera 11, 34151Trieste, Italy.
J Phys Chem Lett. 2022 Dec 15;13(49):11391-11397. doi: 10.1021/acs.jpclett.2c02750. Epub 2022 Dec 1.
Interfacial vibrational footprints of the binary mixture of sodium dodecyl sulfate (SDS) and hexaethylene glycol monododecyl ether (CE) were probed using heterodyne detected vibrational sum frequency generation (HDVSFG). Our results show that in the presence of CE at CMC (70 μM) the effect of SDS on the orientation of interfacial water molecules is enhanced 10 times compared to just pure surfactants. The experimental results contest the traditional Langmuir adsorption model predictions. This is also evidenced by our molecular dynamics simulations that show a remarkable restructuring and enhanced orientation of the interfacial water molecules upon DS adsorption to the CE surface. The simulations show that the adsorption free energy of DS ions to a water surface covered with CE is an enthalpy-driven process and more attractive by ∼10 compared to the adsorption energy of DS to the surface of pure water.
使用差频探测振动和频光谱（HDVSFG）探测了十二烷基硫酸钠（SDS）和六乙二醇单十二醚（CE）二元混合物的界面振动足迹。我们的结果表明，在 CMC（70 μM）存在 CE 的情况下，与仅存在纯表面活性剂相比，SDS 对界面水分子取向的影响增强了 10 倍。实验结果与传统的朗缪尔吸附模型预测相矛盾。这也得到了我们分子动力学模拟的证实，模拟表明，DS 离子在 CE 表面吸附时，界面水分子会发生显著的重排和增强取向。模拟表明，DS 离子在覆盖有 CE 的水表面上的吸附自由能是一个焓驱动的过程，与 DS 离子在纯水表面上的吸附能相比，吸引力增加了约 10 倍。
