Interfacial Density Profiles of Polar and Nonpolar Liquids at Hydrophobic Surfaces
Interfacial Density Profiles of Polar and Nonpolar Liquids at Hydrophobic Surfaces
复制标题
疏水表面极性和非极性液体的界面密度分布
DOI：
10.1021/acs.langmuir.9b03785
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发表时间：
2020
期刊：
影响因子：
3.9
通讯作者：
Dutta, Pulak
中科院分区：
文献类型：
--
作者：
Chu, Miaoqi;Miller, Mitchell;Dutta, Pulak
已知在水和疏水表面之间存在密度耗竭区域(“间隙”)。利用X射线反射率，我们观察到疏水自组装单分子膜(SAM)与其他四种极性液体之间存在类似的间隙。对于这些液体和水，观察到的电子密度损耗不是零，并且在大多数情况下略大于可归因于SAM表面的氢原子层的损耗。另一方面，从所研究的三种非极性液体与自组装膜界面观察到的X射线反射率可以解释为无间隙或有较小的间隙。因此，极性液体(包括但不限于水)甚至远离疏水表面的末端氢原子，而非极性液体则穿透末端区域。间隙的大小与液体-SAM接触角、极性液体的相对极性或其体积密度之间没有一致的相关性。
A density-depleted region (“gap”) is known to exist between water and hydrophobic surfaces. Using X-ray reflectivity, we have observed similar gaps between hydrophobic self-assembled monolayers (SAMs) and four other polar liquids. For these liquids and for water, the observed electron density depletion is nonzero and is in most cases slightly greater than the depletion attributable to the layer of hydrogen atoms at the SAM surface. On the other hand, the observed X-ray reflectivity from the interfaces between SAMs and three nonpolar liquids studied can be explained either without gaps or with smaller gaps. Thus, polar liquids (including but not limited to water) stand away from even the terminal hydrogen atoms at hydrophobic surfaces, while nonpolar liquids interpenetrate the terminal region. There is no consistent correlation between the sizes of the gaps and the liquid–SAM contact angles, the relative polarities of the polar liquids, or their bulk densities.