Colloids as Models for Crystals and Glasses

非技术摘要胶体是悬浮在液体中的小颗粒的集合。它们出现在日常生活中许多不同的地方，如油漆和牛奶。这些胶体的性质可以通过改变颗粒的大小和组成来控制，从而使它们成为原子系统的模型。本项目将探索胶体的性质，以更好地了解原子和分子体系的不同相(液体、晶体、玻璃)。胶体在这项研究中提供了一个优势，因为可以在3D中跟踪单个颗粒的位置。此外，PI将开发新的技术，允许更多地控制胶体中的颗粒。该项目将为研究生和本科生提供最先进的合成和测量技术方面的培训。此外，实验的相对简单和可视化使它们非常容易被公众访问。技术摘要本项目将使用胶体粒子作为模型来研究各种固相的有趣和重要的相行为。胶体提供了独特的优势，因为可以跟踪单个粒子的运动。这使得能够在分子水平上对复杂的动态过程进行直接的三维、时间相关的成像，例如结晶、成核或变形；这些过程对于胶体系统以及分子系统都是常见的。这一能力将被用于研究固体相行为的新性质，包括非晶态和结晶态之间的相变，固体-固体相变，以及非晶态和晶体材料界面的性质和动力学。该项目的一个重要部分是开发新的实验工具。其中一种是电瓶，其中的颗粒密度由介电泳法控制。正在开发新类型的电极，以帮助研究相变，特别是熔融和固-固相变中的均匀晶体成核。正在开发的第二种工具是一种高灵敏度的牵引力方法，用于测量胶体晶体或玻璃在变形过程中的应力。该工具还将为流变学社区提供一种新的、高度灵敏的仪器。这种胶体还提供了一个独特的机会来研究各种随机和工程的三维晶界的迁移率和波动动力学。

Non-technical AbstractColloids are collections of small particles suspended in a liquid. They occur in many different places in everyday life, such as paints and milk. The properties of these colloids can be controlled by varying the size and composition of the particles allowing them to serve as models for atomic systems. This project will explore the properties of colloids to obtain a better understanding of the various phases (liquids, crystals, glasses) of atomic and molecular systems. Colloids offer an advantage in this study since the location of individual particles can be tracked in 3D. In addition, the PI's will develop new techniques that will allow more control of the particles in the colloids. The project will provide training for graduate and undergraduate students in state-of-the-art synthesis and measurement techniques. In addition, the relative simplicity and the visual character of the experiments make them highly accessible to the public.Technical AbstractThis project will use colloidal particles as models for the study of interesting and important phase behavior of a variety of solid phases. Colloids offer the unique advantage in that the motion of individual particles can be tracked. This enables direct three-dimensional, time-dependent imaging of complex dynamic processes, such as crystallization, nucleation or deformation, on the molecular level; these processes are common to both colloidal systems as well as molecular systems. This capability will be exploited in the work proposed to investigate new properties of the phase behavior of solids, including phase transitions between amorphous and crystalline states, solid-solid phase transitions and the nature and dynamics of the amorphous state and the interfaces of crystalline materials. An important part of the project is the development of new experimental tools. One of them is the "electric bottle", in which the particle density is controlled by dielectrophoresis. New types of electrodes are being developed to aid in the study of phase transformations, in particular homogeneous crystal nucleation from the melt and solid-solid transformations. A second tool being developed is a highly sensitive traction-force method for measuring the stress in a colloidal crystal or glass during deformation. The tool will also present the rheology community with a new, highly sensitive instrument. The colloids also provide a unique opportunity to study the mobility and fluctuation dynamics of a large variety of random and engineered three-dimensional grain boundaries.