Structure, Dynamics and Phase Transitions of Suspensions of Polymer Spheres in Equilibrium and Nonequilibrium States

DMR-9501865 Ackerson 实验和建模研究，旨在了解强相互作用的球形粒子系统的集体行为将进行。 实验将利用聚合物球的胶体悬浮液的大的长度和时间尺度特性来探测平衡和非平衡集体性质，如熔化，晶体成核和生长，剪切诱导熔化和流变学。 实验技术包括光学显微镜和数字图像分析，静态和准弹性光散射，和X射线衍射。 建模将侧重于探索液体结构，平衡熔化和剪切诱导熔化的几何和拓扑缺陷的作用。 相互作用的球形粒子（胶体）系统在凝聚态物理学中具有重要意义。 它们是展示仍然知之甚少的熔融-结晶转变的最简单方法。 胶体表现出相互作用的柔软性、运动的缓慢性和颗粒之间的大间距的独特组合，使得它们能够有效地用于球形颗粒行为的研究。 涉及各种光学技术的实验将与模型计算相结合，以研究再结晶和玻璃形成以及结构缺陷的重要性。 ***

DMR-9501865 Ackerson Experimental and modeling studies directed toward understanding the collective behavior of strongly interacting spherical particle systems will be carried out. Experiments will exploit the large length and time scales characteristic of colloidal suspensions of polymer spheres to probe equilibrium and nonequilibrium collective properties such as melting, crystal nucleation and growth, shear-induced melting and rheology. Experimental techniques include optical microscopy and digital image analysis, static and quasielastic light scattering, and x-ray diffraction. The modeling will focus on exploring the roles of geometric and topological defects on liquid structure, equilibrium melting, and shear-induced melting. %%% Systems of interacting spherical particles (colloids) are of fundamental interest in condensed matter physics. They are the simplest way to exhibit the still poorly understood melting-crystallization transition. Colloids exhibit the unique combination of softness of interaction, slowness in motion, and large spacing between particles that enables their effective use in the study of spherical particle behavior. Experiments involving a variety of optical techniques will be combined with model calculations to study recrystallization and glass formation as well as the importance of structural defects. ***