论文标题
甲苯二烷酰胺的吸附膜的同步加速器X射线反射率研究
Synchrotron X-Ray Reflectivity Study of the Adsorption Film of Octadecanamide at the Toluene-Water Interface
论文作者
论文摘要
X射线反射仪使用具有15 keV的光子能量的同步加速器辐射研究了平面甲苯 - 水界面上的吸附甲氧酰胺膜的结构。电子密度（极化）曲线（根据其界面结构取决于水子类中的pH水平）是在借助模型无关的方法从实验数据中重建的。对于高pH〜11，吸附膜是一种晶体八多烷酰胺单层，厚度约为2.6 nm，其中表面活性剂的脂族尾巴沿正常延伸至表面。对于低pH〜2，直接在甲苯 - 水界面上的晶体单层组成的表面结构的厚度和沉积的甲氧酰胺胶束的厚层达到约50 nm。我们认为，非离子表面活性剂胶束的凝结显着增加，其表面活性剂的表面浓度显着增加是由于极化方向的变化引起的，而在水亚语和八甲胺单层之间的界面上pH值降低。重建的电子密度曲线的形状还表明，表面活性剂胶束最近接近界面的平面在距离距离约7 nm的距离上存在。
The structure of an adsorption octadecanamide film at the planar toluene-water interface is studied by X-ray reflectometry using synchrotron radiation with photon energy of 15 keV. The electron density (polarizability) profiles, according to which the interface structure is determined by the pH level in the water subphase, are reconstructed from experimental data with the help of a model-independent approach. For a high pH~11, the adsorption film is a crystalline octadecanamide monolayer with a thickness of about 2.6 nm, in which aliphatic tails of surfactant are extended along the normal to the surface. For low pH ~ 2, the thickness of the surface structure consisting of the crystalline monolayer directly on the toluene-water interface and a thick layer of deposited octadecanamide micelles reaches about 50 nm. In our opinion, the condensation of nonionogenic surfactant micelles for which the surface concentration of the surfactant increases significantly is caused by a change in the polarization direction upon a decrease in the pH level in the electric double layer at the interface between the water subphase and the octadecanamide monolayer. The shape of the reconstructed electron density profiles also indicates the existence of a plane of the closest approach of surfactant micelles to the interface at a distance of about 7 nm from it.
