Interfaces and dynamics in complex fluids: non-additive mixtures

胶体分散体是由粒径在1 nm ~ 1 μ m的介观颗粒分散在液体中形成的复杂流体。存在大量不同类型的颗粒，其具有不同的形状、尺寸、电荷、表面和介电性质，以及相当大范围的不同类型的溶剂，包括水性和非水性溶剂，其还包括添加剂，例如作为盐或耗尽剂。日常的胶体分散体的例子包括牛奶、血液和油漆。除了具有许多重要的工业应用外，良好表征的合成胶体分散体还作为重要的模型系统来研究凝聚态物质中各种各样的基本体积、界面和动力学现象。这两个物种都被模拟为硬球;然而，不相似物种的球体对之间的交叉相互作用与人们从它们的几何形状推断的不同，即排斥发生在小于或大于个体直径算术平均值的距离处。这种非加性硬球模型具有有趣的性质，从液-液相分离的发生到高密度下的聚集现象。在实际的胶体分散体中，由于粒子上存在电荷或磁偶极子，所以会出现非加和性.我们将利用我们先前发展的用于该模型的密度泛函理论以及计算机模拟来研究非加和硬球模型的各种相关的界面和动力学现象.我们的目的是深入了解如何竞争的长度尺度，支配这个模型影响自由液-液界面的性质，吸附行为在墙壁和毛细管，和动态相关性在散装和接口，以及如何这样的接口响应于外部领域，驱动系统的平衡，因为是相关的，例如，在thedynamics的沉降和分散体暴露于剪切流。

Colloidal dispersions are complex fluids of mesoscopicparticles with sizes between 1nm and 1micron that are dispersed in aliquid. There is a large variety of different types of particles withvarying shape, size, charge, surface and dielectric properties, aswell as a considerable range of different types of solvents, bothaqueous and non-aqueous, which also include additives such as salt ordepletion agents. Everyday examples of colloidal dispersions includemilk, blood, and paint. Besides possessing many important industrialapplications, well-characterized synthetic colloidal dispersions serveas important model systems to investigate a wide variety offundamental bulk, interfacial and dynamical phenomena in CondensedMatter.Here we consider a theoretical model for colloidal dispersions withtwo different types of particles. Both species are modelled as hardspheres; the cross interaction between pairs of spheres of unlikespecies is however different from what one would infer from theirgeometric shapes, i.e. the repulsion occurs at a distance that issmaller or larger than the arithmetic mean of the individualdiameters. This non-additive hard sphere model has interestingproperties ranging from the occurrence of liquid-liquid phaseseparation to clustering phenomena at high densities. In realcolloidal dispersions non-additivity occurs due to the presence ofelectrical charges or magnetic dipoles on the particles.We will investigate a wide variety of relevant interfacial anddynamical phenomena of the non-additive hard sphere model using bothour previously developed density functional theory for this model aswell as computer simulations. Our aim is to gain insight into how thecompetition of the length scales that govern this model affects theproperties of free liquid-liquid interfaces, of adsorption behaviourat walls and in capillaries, and of dynamical correlations in bulk andat interfaces, and how such interfaces respond to external fields thatdrive the system out-of-equilibrium, as is relevant e.g. in thedynamics of sedimentation and for dispersions exposed to shear flow.