Peng Mengsu, Duignan Timothy T, Zhao Xiu Song, Nguyen Anh V
School of Chemical Engineering, University of Queensland, Brisbane, Queensland 4072, Australia.
J Phys Chem B. 2020 Apr 16;124(15):3195-3205. doi: 10.1021/acs.jpcb.0c00278. Epub 2020 Mar 3.
Soluble surfactants form thick adsorption layers at the air-liquid interface, but classical adsorption models fail to account for it as they treat the adsorption layer as a mathematical plane (of zero thickness). This simplification has produced several inconsistencies between theoretical predictions and experimental results, especially for the surface potential. Here, we develop a new adsorption model for ionic surfactants at the air-water interface that incorporates the effect of the adsorption layer thickness using a modified Poisson-Boltzmann equation that integrates information from molecular dynamics simulation. We show that the surface potential depends sensitively on both the thickness of the adsorption layer and the interfacial depth at which the surface potential is probed. This model, therefore, provides a much more accurate picture of the surface potential than classical models.
可溶性表面活性剂在气液界面形成厚吸附层，但经典吸附模型无法解释这一现象，因为它们将吸附层视为一个数学平面（厚度为零）。这种简化导致理论预测与实验结果之间出现了一些不一致，尤其是在表面电势方面。在此，我们开发了一种新的离子型表面活性剂在空气-水界面的吸附模型，该模型使用修正的泊松-玻尔兹曼方程纳入吸附层厚度的影响，该方程整合了分子动力学模拟的信息。我们表明，表面电势敏感地依赖于吸附层的厚度以及探测表面电势的界面深度。因此，该模型比经典模型更准确地描述了表面电势。
