Department of Earth Science and Engineering, Imperial College, London, SW7 2AZ, United Kingdom.
Langmuir. 2011 Sep 20;27(18):11475-80. doi: 10.1021/la202028p. Epub 2011 Aug 18.
Particle stabilized thin films occur in a range of industrial applications where their properties affect the efficiency of the process concerned. However, due to their dynamic and unstable nature they are difficult to observe experimentally. As such, a tractable way of gaining insight into the fundamental aspects of this complicated system is to use computer simulations of particles at interfaces. This paper presents modeling results of the effect of nonuniform packing of spherical particles on the stability of thin liquid films. Surface Evolver was used to model cells containing up to 20 particles, randomly packed in a thin liquid film. The capillary pressure required to rupture the film for a specific combination of particle arrangement, packing density, and contact angle was identified. The data from the periodic, randomly packed models has been used to find a relationship between particle packing density, contact angle, and critical capillary pressure which is refined to a simple equation that depends on the film loading and contact angle of the particles it contains. The critical capillary pressure for film rupture obeys the same trends observed for particles in regular 2D and 3D packing arrangements. The absolute values of P*(crit), however, are consistently lower than those for regular packing. This is due to the irregular arrangement of the particles, which allows for larger areas of free film to exist, lowering the critical capillary pressure required to rupture the film.
颗粒稳定的薄膜出现在一系列工业应用中，其性质影响着相关过程的效率。然而，由于其动态和不稳定的性质，它们很难在实验中观察到。因此，一种可行的方法是使用界面处颗粒的计算机模拟来深入了解这个复杂系统的基本方面。本文介绍了颗粒非均匀堆积对薄液膜稳定性影响的建模结果。使用 Surface Evolver 对包含多达 20 个颗粒的单元进行建模，这些颗粒随机填充在薄液膜中。确定了对于特定的颗粒排列、堆积密度和接触角组合，使薄膜破裂所需的毛细压力。从周期性、随机堆积的模型中获得的数据用于找到颗粒堆积密度、接触角和临界毛细压力之间的关系，该关系被细化为一个简单的方程，该方程取决于包含的薄膜载荷和颗粒的接触角。薄膜破裂的临界毛细压力遵循与规则 2D 和 3D 堆积排列中观察到的相同趋势。然而，P*(crit)的绝对值始终低于规则堆积的绝对值。这是由于颗粒的不规则排列，允许存在更大的自由膜面积，从而降低了使薄膜破裂所需的临界毛细压力。
