Department of Metallurgical Engineering, College of Mines and Earth Sciences , University of Utah , 135 South 1460 East , Rm 412, Salt Lake City , Utah 84112 , United States.
Physical Sciences Division , Pacific Northwest National Laboratory , 902 Battelle Boulevard , Richland , Washington 99352 , United States.
J Phys Chem B. 2019 Mar 14;123(10):2397-2404. doi: 10.1021/acs.jpcb.9b01246. Epub 2019 Mar 1.
The features of interfacial water at air-water interfaces of anionic sodium dodecyl sulfate (SDS) and cationic dodecyl amine hydrochloride (DDA) solutions were examined by combining sum frequency generation (SFG) vibrational spectroscopy measurements and molecular dynamics simulations (MDS). The SFG spectra revealed that interfacial water molecules for SDS solutions were highly ordered compared with those for DDA solutions. To elucidate this observation, in addition to agreement with the literature in regards to the interfacial electric field at the interfaces, we investigated the features of interfacial water molecules with respect to their network and their interaction with surfactant head groups. Our simulation analysis results revealed a higher number density, more strongly connected hydrogen bonding, and more orderly oriented interfacial water molecules at the interface of the SDS solutions as compared to the DDA solutions. The goal of this research is to identify significant features of interfacial water for our improved understanding of such interfacial phenomena.
通过结合和频产生（SFG）振动光谱测量和分子动力学模拟（MDS），研究了阴离子十二烷基硫酸钠（SDS）和阳离子十二烷基胺盐酸盐（DDA）溶液在气液界面处的界面水的特征。SFG 谱表明，与 DDA 溶液相比，SDS 溶液的界面水分子高度有序。为了解释这一观察结果，除了与文献中关于界面处的界面电场的一致性之外，我们还研究了界面水分子的特征，包括它们的网络以及它们与表面活性剂头基的相互作用。我们的模拟分析结果表明，与 DDA 溶液相比，SDS 溶液界面处的界面水分子具有更高的密度、更强的氢键连接和更有序的取向。这项研究的目的是确定界面水的重要特征，以便我们更好地理解这种界面现象。
