Department of Chemistry, University of North Carolina-Chapel Hill, Chapel Hill, North Carolina 27599, USA.
Langmuir. 2011 Oct 4;27(19):11737-41. doi: 10.1021/la202157q. Epub 2011 Sep 7.
Hydrophobic surfaces created by the adsorption of a monolayer of surfactants, such as CTAB or DODAB, to mica display long-range mutual attraction when placed in water. Initially, this attraction was considered to be due to hydrophobic interaction, but more careful measurements using AFM showed that the surfactant monolayer undergoes rearrangements to produce charged patches on the surface; therefore, the nature of the long-range interaction is due to the electrostatic interaction between patches. The monolayer rearrangement depends on the nature of the surfactant and its counterion. To study possible monolayer rearrangements in molecular detail, we performed detailed molecular dynamics computer simulations on systems containing a monolayer of surfactants RN(CH(3))(3)(+)Cl(-) (R indicates a saturated hydrocarbon chain) adsorbed on a mica surface and immersed in water. We observe that when chain R is 18 carbons long the monolayer rearranges into a micelle but it remains a monolayer when the chain contains 24 carbons.
当吸附在云母表面的单分子层表面活性剂（如 CTAB 或 DODAB）被放置在水中时，会形成疏水面，从而在远处表现出相互吸引力。最初，这种吸引力被认为是由于疏水相互作用，但使用 AFM 进行更仔细的测量表明，表面活性剂单层会发生重排，在表面产生带电斑块；因此，长程相互作用的性质是由于斑块之间的静电相互作用。单层重排取决于表面活性剂的性质及其反离子。为了详细研究可能的单层重排，我们对含有吸附在云母表面并沉浸在水中的表面活性剂 RN(CH(3))(3)(+)Cl(-)（R 表示饱和烃链）单层的系统进行了详细的分子动力学计算机模拟。我们观察到，当链 R 长 18 个碳原子时，单层会重排成胶束，但当链长为 24 个碳原子时，单层仍保持不变。
