Calculation of the Interfacial Tension of Nanostructured Interfaces by Molecular Dynamics Simulations Using Thermodynamic Integration

提出了一种新的计算流体与任意材料界面张力的分子动力学方法。该方法建立在热力学积分的基础上。真实的原子模型材料的表面被可逆地变换成无结构的平坦的排斥壁，并计算了沿这一路径的自由能变化。由于流体与该参照面之间的界面张力可以很容易地计算出来，因此也可以得到与真实表面之间的界面张力。这种方法将应用于水和水溶液之间的界面张力，以及纳米结构疏水固体(如烷烃和全氟烷烃晶体)的界面张力。这些材料是制造技术超疏水表面的主要候选材料。这些模拟的目的是找出是否可以通过在表面创建纳米尺寸的凹痕来增加它们的疏水性。

A new molecular dynamics method for calculation the interfacial tension between fluids and arbitrary materials will be developed. The method is based on thermodynamic integration. The surface of the real, atomistically modeled material is reversibly transformed into an unstructured, flat repulsive wall, and the free-energy change along this pathway is calculated. As the interfacial tension between the fluid and this reference surface can be easily evaluated, also the interfacial tension with the real surface can be obtained. The method will be applied to the interfacial tension between water and aqueous solutions on the one side and nanostructured hydrophobic solids such as alkane and perfluoroalkane crystals on the other. These materials are prime candidates for the creation of technical superhydrophobic surfaces. The simulations are aimed at finding out if their hydrophobicity can be increased by creating nanometer-sized indentations on the surface.