Research Initiation Award Grant - Colloidal Mixtures: Microstructure and Mechanics

研究启动奖--胶体混合物：微观结构和力学--研究广泛应用于商业和工业产品中的胶体颗粒混合物。在许多应用中，当胶体体积分数、胶体相互作用的强度和性质等参数变化时，胶体悬浮液会在流体和无序固体之间转换。理解微观和宏观性质之间的联系仍然是胶体科学领域的一个中心挑战。X射线光子相关光谱(XPCS)是一种非常适合于揭示玻璃胶体悬浮液中显著的纳米尺度结构动力学的技术。该项目以新的方式将XPCS与流变学相结合，在纳米胶体悬浮液混合物的微观动力学和流变学之间建立了直接的联系。该项目将包括四个阶段：1)通过研究双峰尺寸分布和胶体之间的内在短程引力的结果，实验将为控制悬浮相行为和流变学开辟一条新的途径。2)这些胶体材料的微观结构、动力学和力学响应的实验表征将为严格检验不同的理论提供一系列基准。3)根据测量的微观结构预测流动性质的理论的发展将导致对流变性质的微观理解。再加上对实验控制变量如何影响这些微观参数的了解，为控制稠密悬浮液和凝胶的流动特性开辟了途径。4)阿贡国家实验室将开发研究胶体凝胶动力学的技术，这将对研究各种软凝聚物质系统的动力学非常有用，并将引起ANL的许多其他用户的兴趣。该项目预计将导致对凝聚态系统动力学的基本和微观理解，并通过控制它们的流变性和流动特性来革命性地处理这类系统。

The Research Initiation Award entitled - Colloidal Mixtures: Microstructure and Mechanics - investigates mixtures of colloidal particles which are used in a wide array of commercial and industrial products. In many applications, the colloidal suspensions transform between fluid and disordered solid states when parameters such as the colloidal volume fraction and the strength and nature of the colloidal interactions are varied. Understanding the connection between the microscopic and macroscopic properties remains a central challenge for the field of colloid science. X-ray photon correlation spectroscopy (XPCS) has emerged as a technique uniquely suited for revealing the salient nanometer-scale structural dynamics in glassy colloidal suspensions. This project combines XPCS with rheometry in new ways to make direct connections between the microscopic dynamics and rheology of mixtures of nanocolloidal suspensions.The project will consist of four stages: 1) By investigating the consequences of a bimodal size distribution combined with intrinsic short-range attractions between colloids, the experiments will open a new avenue for controlling suspension phase behavior and rheology. 2) The experimental characterization of the microstructure, dynamics and mechanical response in these colloidal materials will provide a series of benchmarks for rigorous testing of different theories. 3) The developed theory of predicting the flow properties from measured microstructures will result in a microscopic understanding of the rheological properties. Coupled with the knowledge of how experimentally controlled variables affect these microscopic parameters opens up avenues for controlling the flow properties of dense suspensions and gels. 4) Techniques will be developed at Argonne National Laboratory to study the dynamics of colloidal gels and this will be extremely useful in studying the dynamics of a variety of soft condensed matter systems and will be of interest to a number of other users at ANL. The project is expected to lead to a fundamental and microscopic understanding of dynamics of condensed matter systems and to revolutionize processing of such systems by control of their rheology and flow properties.