Departament de Ciència de Materials i Química Física & Institut de Química Teòrica i Computacional (IQTCUB), Universitat de Barcelona, 08028 Barcelona, Spain.
Departamento de Ingeniería Química, Universidad de Concepción, Concepción POB 160 - C, Chile.
Molecules. 2020 Mar 25;25(7):1499. doi: 10.3390/molecules25071499.
Interfacial properties such as interfacial profiles, surface activity, wetting transitions, and interfacial tensions along the three-phase line are described for a Type IIIa binary mixture. The methodological approach combines the square gradient theory coupled to the statistical associating fluid theory for Mie potentials of variable range, and coarse-grained molecular dynamics simulations using the same underlying potential. The water + hexane mixture at three-phase equilibrium is chosen as a benchmark test case. The results show that the use of the same molecular representation for both the theory and the simulations provides a complementary picture of the aforementioned mixture, with an excellent agreement between the molecular models and the available experimental data. Interfacial tension calculations are extended to temperatures where experimental data are not available. From these extrapolations, it is possible to infer a first order wetting transition at 347.2 K, where hexane starts to completely wet the water/vapor interface. Similarly, the upper critical end point is estimated at 486.3 K. Both results show a very good agreement to the available experimental information. The concentration profiles confirm the wetting behavior of hexane along with a strong positive surface activity that increases with temperature, contrasting the weak positive surface activity of water that decreases with temperature.
界面特性，如三相线处的界面轮廓、表面活性、润湿转变和界面张力，对于 IIIa 型二元混合物进行了描述。该方法结合了平方梯度理论和变程 Mie 势的统计关联流体理论，以及使用相同基础势的粗粒分子动力学模拟。选择水+己烷三相平衡混合物作为基准测试案例。结果表明，理论和模拟中使用相同的分子表示提供了对上述混合物的互补描述，分子模型与可用实验数据之间具有极好的一致性。界面张力计算扩展到没有实验数据的温度。从这些外推，我们可以推断出在 347.2 K 时存在一级润湿转变，此时己烷开始完全润湿水/蒸汽界面。同样，估计上临界端点在 486.3 K。这两个结果与可用的实验信息非常吻合。浓度分布证实了己烷的润湿行为以及随温度升高而增加的强烈正表面活性，与随温度降低而减小的水的弱正表面活性形成对比。
