Adsorption of Charge-Bidisperse Mixtures of Colloidal Particles
Adsorption of Charge-Bidisperse Mixtures of Colloidal Particles
复制标题
胶体颗粒电荷双分散混合物的吸附
作者：
Jeffrey J. Gray;R. Bonnecaze
仔细控制胶体颗粒的吸附单层的微观结构对于通过自组装过程产生纳米结构的器件是重要的，并且自组装颗粒单层的结构和功能复杂性随着系统中的组件的数量而增加。在这里，我们进行模拟的布朗，胶体颗粒的二元混合物的吸附，探索和识别参数的组合，产生技术上有趣的表面结构。该系统包含两种类型的粒子相同的半径，但不同的表面电位。在一种方案中，布朗动力学模拟开始于带电平面表面上方的均匀分布的混合物，并且颗粒吸附到表面，直到系统达到稳态。在第二种方案中，两种不同的单组分悬浮液依次暴露于基板。体积分数在散装控制相对表面覆盖率，所观察到的结构包括孤立的，高电位粒子和链和低电位粒子簇。取代无序晶格形式的粒子电位的比例范围从约1.5至4，这取决于参数：有序晶格更稳定的双分散性在较高的壁电位和较高的粒子电位。基于等效硬盘（EHD）半径的终端分数双分散性从3.6%到10%不等。在顺序吸附，少量的第二组分吸附仅用于参数组合与最小的排斥从预吸附的颗粒和足够的吸引力的表面，因为胶体吸附是一个动力学受挫的过程。高电位粒子添加到低电位粒子的单层中，形成孤立的点，反过来，低电位粒子掺杂高电位粒子的晶格。根据晶格模型和EHD模型对模拟结果进行了讨论。
Careful control of the microstructure of an adsorbed monolayer of colloidal particles is important for creating nanostructured devices through self-assembly processes, and the structural and functional complexity of self-assembled particulate monolayers increases with the number of components in the system. Here, we perform simulations of the adsorption of binary mixtures of Brownian, colloidal particles to explore and identify combinations of parameters that produce technologically interesting surface structures. The system contains two types of particles of identical radii but differing surface potentials. In one scheme, Brownian dynamics simulations begin with an evenly distributed mixture above a charged planar surface, and the particles adsorb to the surface until the system achieves a steady state. In the second scheme, two different single-component suspensions are exposed to the substrate sequentially. Volume fractions in the bulk control relative surface coverages, and the observed structures include isolated, high-potential particles and chains and clusters of low-potential particles. Substitutionally disordered lattices form for ratios of particle potential ranging from about 1.5 to 4, depending on parameters: ordered lattices are more stable to bidispersity at higher wall potentials and higher particle potentials. Terminal fractional bidispersities based on equivalent hard disk (EHD) radii vary from 3.6 to 10%. In sequential adsorption, small amounts of the second component adsorb only for parameter combinations with minimal repulsions from preadsorbed particles and sufficient attraction to the surface, since colloidal adsorption is a kinetically frustrated process. High-potential particles added to a monolayer of low-potential particles create isolated dots, and in reverse, low-potential particles dope lattices of high-potential particles. The results of the simulations are discussed in the light of lattice models and EHD models.