Development of nano-structured material based on computer simulation of rod-like particles

纳米技术的最新发展认识到控制纳米结构的重要性。棒状和盘状硬质颗粒表现出不同的液晶结构，这表明利用纳米级硬质颗粒的分散性来控制纳米结构是可能的。在这个项目中，我们计划进行计算机模拟，研究由棒状颗粒和盘状颗粒构成的结构。我们还计划了一些实验，通过添加棒状颗粒或棒状分子来检验材料性质的控制。它是一个圆柱体，它的每一端都有一个半球。其形状由直线段上球体中心的扫掠确定。在本研究项目中，我们提出了一种新型的模型粒子--球盘。它是圆柱体的延伸，呈圆盘状。它的形状是由圆盘上球心的扫描决定的。我们考察了平行硬球和硬球的二元混合物的蒙特卡罗模拟结果，提出了混合物状态方程的近似形式。对混合物的分子动力学模拟表明，近晶层结构的形成干扰了分子的层间扩散。单分散硬球的模拟结果表明，盘状粒子对形成柱状结构具有很强的亲和力。模拟快照显示了全局各向同性结构中的局部柱结构。在不同直径的硬球盘的二元混合物的蒙特卡罗模拟中，观察到了分散的圆盘柱状团簇。

Recent development of nanotechnology recognizes importance of control of nano-scale structure. The fact that rod-like and disc-like hard particles show various liquid crystal structures indicates possibility of control of nano-structure by using dispersions of nano-scale hard particles. In this project we planned computer simulations that studied structures made by rod-like particles and disc-like particles. We also planned experiments with which we examined control of material property by adding rod-like particles or rod-like molecules.Spherocylinder is a model representing a rod-like particle. It is a cylinder each end of which is capped with a hemisphere. Its shape is determined by a sweep of the center of a sphere on a line segment. In this research project, we proposed novel type of model particle named spherical disc. It is an extension of the spherocylinder to a disc-like shape. Its shape is determined by a sweep of the center of a sphere on a disc.We examined results of Monte Carlo simulation of binary mixtures of parallel hard spherocylinders and hard spheres to propose an approximation form of equation-of-state of the mixtures. Molecular dynamics simulation of the mixtures shows that formation of smectic layer structure disturbs interlayer diffusion of molecules.Simulation results of monodisperse hard spherical discs indicates that disc-like particles show strong affinity to form columns. Simulation snapshots show local column structures in global isotropic structures. Dispersed column clusters of discs is observed in Monte Carlo simulation of binary mixtures of hard spherical discs of different diameters.