Connecting nanoscale structure and dynamics to rheology and flow of glassy nanocolloidal suspensions

1336166PI：LehenyX-ray光子相关光谱结合其他散射技术和流变学，用于了解三种不同浓缩纳米胶体体系的流变和流动背后的微观结构动力学：具有短程吸引力的二氧化硅纳米胶体的二元混合物；耗竭诱导的胶体凝胶；以及纳米乳液。为这些体系获得的数据将为胶体体系中凝胶-流体和玻璃-流体转变理论的一般性提供测试，并深入了解它们的非线性流变学。当亚微米到纳米级的颗粒悬浮在液体中时，得到的复合材料或胶体可以采用流体、固体或介于两者之间的东西的性质。在许多情况下，材料特性的细微变化可能会极大地改变其机械刚性和流动行为。这种敏感性为设计具有为特定应用量身定做的特性的悬架带来了科学挑战和机遇。事实上，这种控制对从3D打印到食品加工和药物输送的广泛技术至关重要。这笔赠款支持了一种研究胶体悬浮液的新途径，该方法有望扩大可用于控制其刚性和流动的策略，特别是通过阐明两种尺寸的颗粒的悬浮液的独特性质，这些悬浮液具有粘在一起的趋势，可以进行调整。该实验计划的一个关键特征将是应用一种新的X射线技术，该技术能够史无前例地分辨率小至分子长度的软材料中的缓慢微观运动。这些用于研究材料变形和流动的X射线方法的发展将产生远远超出计划的实验的影响，因为它提供了一种新的工具，应用于包括物理、化学工程和生物科学在内的几个传统学科。

1336166PI: LehenyX-ray photon correlation spectroscopy, in conjunction with other scattering techniques and rheometry, is used to understand microstructural dynamics underlying rheology and flow of three different concentrated nanocolloidal systems: binary mixtures of silica nanocolloids with short-range attractive forces; a depletion-induced colloidal gels; and a nanoemulsion. Data obtained for these systems will provide tests for the generality of the theories for gel-fluid and glass-fluid transitions in colloidal systems and insights into their nonlinear rheology.When sub-micron to nanoscale particles are suspended in a liquid, the resulting composite material, or colloid, can adopt properties of a fluid, a solid, or something in between. In many cases, seemingly subtle changes in the characteristics of the material can dramatically alter its mechanical rigidity and flow behavior. This sensitivity creates both a scientific challenge and an opportunity for designing suspensions with properties tailored for specific applications. Indeed, such control is crucial to a vast range of technologies from 3D printing to food processing and drug delivery. This grant supports a novel avenue of investigation into colloidal suspensions that promises to expand the strategies available for controlling their rigidity and flow, particularly by elucidating the unique properties of suspensions of two sizes of particles with a tendency to stick together that can be tuned. A key feature of the experimental program will be the application of a new x-ray technique that enables unprecedented resolution of the slow microscopic motions in soft materials at lengths as small as a molecule. The development of these x-ray methods for investigating materials under deformation and flow will have impact far beyond the planned experiments by providing a new tool with application that spans several traditional disciplines including physics, chemical engineering, and the biosciences.