Relationship of Structural Dynamics and Elasticity in Soft Materials

9971432 weitz该项目将开发实验探针，从而在局部尺度上理解“软”材料的弹性特性，其中材料的结构直接影响其弹性。将研究的材料类型包括胶体悬浮液、凝胶、浓缩乳液和各种生物学上重要的材料，包括肌动蛋白网络、囊泡、模型细胞和细胞本身。许多这些材料在结构上是不均匀的，因此它们的弹性性能在材料的不同区域会有很大的不同。传统的体弹性测量只探测平均性能；这里要开发的方法将探测局部特性，以区分材料的不同组成部分的功能和目的。待开发的探针依赖于对嵌入介质中的探针粒子运动的研究；这个运动要么是热诱导的，要么是由外场驱动的。探针的运动将在这些探针的长度尺度上提供有关材料弹性的重要信息。这项研究将涉及一名博士后和几名研究生。许多重要的材料可能是高度不均匀的，它们的性质在材料的不同区域内会有很大的变化。这种非均匀结构与材料性能的关系对其功能至关重要。例如，一个像细胞一样基本的物体是由各种各样的组件组成的，每个组件都有自己的结构、功能和属性。然而，这些材料的力学或弹性特性的知识通常是通过测量大量材料的响应来获得的；这提供了一些平均信息，但模糊了各个对象之间的重要变化。这项工作的目标是开发新的方法，使这些非均匀材料的弹性或机械性能的非常局部的测量。这些结果将提供对材料组成部分的功能和作用的重要见解，并将有助于新材料的基本原理设计，这些新材料共享甚至改进所研究材料的功能。这项工作将为研究生和博士后提供支持和重要的教育。

9971432WeitzThis project will develop experimental probes leading to an understanding of the elastic properties of "soft" materials on a local scale, where the structure of the material directly influences its elasticity. The types of materials that will be studied include colloidal suspensions, gels, concentrated emulsions, and a variety of biologically important materials including actin networks, vesicles, model cells, and cells themselves. Many of these materials are structurally inhomogeneous, and thus their elastic properties can vary significantly in different regions of the material. Traditional bulk elastic measurements probe only the average properties; the methods to be developed here will probe local properties to differentiate the function and purpose of the different components of the material. The probes to be developed rely on the study of the motion of probe particles embedded within the medium; this motion will either be thermally induced, or driven with an external field. The motion of the probe will provide important information about the elasticity of the material on the length scale of these probes. The study will involve a post doc and several graduate students. %%%Many important materials can be highly inhomogeneous, and their properties can vary significantly within different regions of the material. The relationship of this inhomogeneous structure to the properties of the material can be crucial for its functioning. For example, an object as fundamental as a cell, is comprised of a wide variety of components, each with its own structure and each with its own function and each with its own properties. However, knowledge of the mechanical or elastic properties of such materials is typically obtained by measuring the response of a large collection of them; this provides some average information, but obscures important variations across the individual objects. The goal of this work is to develop new methods for making very local measurements of the elastic or mechanical properties of such inhomogeneous materials. The results will provide important insight into the function and role of the components of the material, and will assist in the rationale design of new materials that share or even improve upon the function of the material under study. This work will provide support and important education for both graduate students and post docs.