Polydispersity Effects in a Colloidal Dispersion Fluid

由于多分散胶体流体是一个复杂的系统，因此不可避免地要引入一个适当的模型，使其能够计算系统的基本性质。此外，为了提高对系统的理解，获得物理量的可用表达式是很重要的。本项目采用硬球Yukawa模型，利用Ornstein-Zernike方程的解析MSA解，成功地得到了静态结构因子、中子（光）散射截面和热力学量的解析表达式。所得到的表达式是有用的和紧凑的，它们提示我们应用于多分散流体。使用这些表达式，我们实际研究了可观测量的大小和相互作用多分散性效应。全文摘要如下：相互作用多分散性对描述胶体区密度波动的结构因子的影响与粒径多分散性的影响在性质上是相同的，但前者的影响弱于后者。在气液过渡临界点附近，相互作用的多分散性对状态方程的等温线有特色性的影响，而大小和相互作用的多分散性效应的方向是相反的。对胶体硬球二元多分散流体的可测结构因子进行了研究。结果发现，该因子有一个特殊的峰值。峰对大小的多分散性非常敏感，随着多分散性的增加，峰逐渐变为驼峰。讨论了这种特殊的结构与胶体颗粒内部的物质分布密切相关。研究了溶剂中胶体颗粒之间的相互作用。讨论了溶剂介导的相互作用可能比范德华相互作用的作用范围更大、更重要。然而，这项工作还需要进一步的研究和改进。少

Since a polydisperse colloidal fluid is a complex system, it is inevitable to introduce an appropriate model which makes it possible to work essential properties of the system. Moreover, in order to improve understanding of the system it is important to obtain available expressions of physical quantities. In the present project, we employed the hard sphere Yukawa model for the system, and using the analytical MSA solution of the Ornstein-Zernike equation we succeeded to obtain analytical expressions for the static structure factor, the neutron (or light) scattering cross section and the thermodynamical quantities. The expressions obtained is useful and compact, and they prompt us to apply to the polydisperse fluids. Using the expressions, we actually worked the size and interaction polydispersity effects on observable quantities. The abstract of the work is as follows:1. The interaction polydispersity effect on the structure factor describing the density fluctuation in the colloidal pa … More rticle numbers is qualitatively the same effect as the size polydispersity has, but the former effect is weaker than the latter.2. The interaction polydispersity has a characteristic effect on the isotherm of the equation of state near the critical point of the gas-liquid transition, and the directions of the size and interaction polydispersity-effects are opposite.3. The measurable structure factor was investigated for the binary-pecies polydisperse fluid of colloidal hard spheres. It was found that the factor has a peculiar peak. The peak is very sensitive to the size polydispersity and changes gradually to the hump already known as the polydispersity increases. It was discussed that the peculiar structure is closely related to material distribution inside colloidal particles.The interaction between colloidal particles in a solvent was worked. It was discussed that the solvent-mediated interaction could be longer-range and more important than the van der Waals interaction. However, this work needs further investigation and improvement. Less