Role of Composition on Mesostructure-Flow Interaction and Rheology of Particle Laden Interfaces

CBET-1437710乳状液和泡沫等悬浮液的物理性质会受到吸附在液-液或液-气界面上的小颗粒的强烈影响。这个项目将探索吸附颗粒的存在、它们的组成以及它们在界面上的排列方式，这被称为它们的介观结构，它们如何影响界面的流变性。结果将被用来确定细观结构对界面流变性的作用。结构和流变学之间的这种关系很重要，因为在消费化妆品、食品、药物输送应用和提高石油采收率中发现的许多制造化学过程使用的乳液具有颗粒加载或颗粒覆盖的界面。研究人员将利用该项目的结果开发一系列信息量大、引人入胜的模块，教师可以使用这些模块向大学和中学生教授流体力学原理。颗粒界面的细观结构受到颗粒间作用力的影响，而颗粒间的作用力取决于组成。细观结构抵抗了流动诱导的变形，导致了界面的粘弹性。使用界面流变仪，研究人员将表征组成对颗粒界面平衡细观结构的作用，表征组成对变形界面的流变学和细观结构的作用，并将组成的变化(如颗粒表面浓度、颗粒大小和多分散性以及表面活性剂浓度)与颗粒间力和粘性力联系起来。

CBET-1437710The physical properties of suspensions such as emulsions and foams can be strongly affected by the presence of small particles that adsorb onto liquid-liquid or liquid-gas interfaces. This project will explore how the presence of adsorbed particles, their composition, and the arrangements they can take on an interface, which is called their mesostructure, can influence the rheology of the interface. An interfacial rheometer has been developed for this study, which will allow investigators to measure characteristics of the interface and simultaneously observe particles at the interface. The results will be used to determine the role of mesostructures on interfacial rheology. This relationship between structure and rheology is important, because many manufacturing chemical processes found in consumer cosmetics, food products, drug delivery applications, and enhanced oil recovery use emulsions that have particle-laden or particle-covered interfaces. The information gathered in this project will be useful to scientists and engineers who formulate such products and design large-scale processes to manufacture them. The investigators will use results from the project to develop a series of informative and engaging modules that can be used by instructors to teach fluid dynamics principles to university and middle-school students.The mesostructure in particle-laden interfaces are affected by interparticle forces, which depend on composition. The mesostructure resists flow-induced deformation, resulting in an interfacial viscoelasticity. The nature of particle interactions on an interface differs from that in the bulk, primarily because of an anisotropic capillary attraction between interfacial particles. Using the interfacial rheometer, investigators will characterize the role of composition on the equilibrium mesostructure of particle-laden interfaces, characterize the role of composition on the rheology and mesostructure of deforming interfaces, and relate changes in composition such as particle surface concentration, particle size and polydispersity, and surfactant concentration to interparticle forces and viscous forces. Viscoelasticity of such interfaces affects dynamical behavior of emulsions, including drop deformation, coalescence and breakup. Understanding the relationship between composition and rheology will allow practitioners to tailor interfaces and engineer materials with desired properties.