Colloids in molten inorganic salts and liquid metals

非技术概述：胶体态在生物学、化学和材料科学中无处不在。它提供了一种通用的方法来创造高度不同成分的宏观均匀组合，例如牛奶由不相容的脂肪和水组成。在不同的系统中稳定胶体状态是许多技术过程的核心。这个项目的重点是一类新的胶体系统。初步研究表明，不同的纳米颗粒在熔融无机盐中可以实现胶体状态，也可能在液态金属中实现胶体状态。液态金属和熔盐广泛应用于冶金和焊接，作为热太阳能技术中的传热流体，以及其他重要领域。在这种介质中展示稳定的胶体系统，并了解控制稳定性的因素，可能为利用胶体化学丰富的技术工具箱设计新型复合材料提供机会。一项全面的教育和推广计划伴随着这项研究，重点是为芝加哥南部代表性不足的非裔美国人和西班牙裔K-12人口提供丰富的教育。该项目支持为美国芝加哥化学社区以及K-12学生提供纳米科学教育资源的持续开发和分发。这包括在芝加哥大学开发新的研究生材料化学轨道，并继续成功地帮助本科生和高中生获得研究经验。技术概述：本项目与新型胶体系统的开发直接相关。各种过渡金属、半导体、稀土和磁性材料的纳米粒子在各种熔盐和液态金属中形成稳定的胶体分散体。纳米颗粒在这些介质中的胶体稳定性不能用传统的稳定机制来解释。静电斥力和位阻斥力似乎都不能解释熔融离子盐中的胶体稳定性。由于电荷密度非常高，静电势在亚纳米距离上被屏蔽，使得静电斥力距离较短且不如范德华引力。熔盐中颗粒表面刷状物质的缺失也排除了经典空间稳定的可能性。该项目结合了这类在熔融无机盐和液态金属中胶体稳定的功能纳米材料的系统实验和理论研究。该项目的具体目标包括研究和发展熔盐和液态金属在高温下的胶体稳定机制，以及探索纳米材料在熔盐和液态金属中的胶体分散的性质和潜在应用。

NON-TECHNICAL SUMMARY:The colloidal state is ubiquitous in biology, chemistry, and materials science. It offers a general way to create macroscopically homogeneous combinations of highly dissimilar components, such as milk consisting of immiscible fat and water. Stabilizing the colloidal state in different systems is at the heart of many technological processes. This project is focused on a novel class of colloidal systems. Preliminary studies show that a colloidal state can be realized for different nanoparticles in molten inorganic salt and, probably, in liquid metals. Liquid metals and molten salts are widely used in metallurgy and soldering, as heat transfer fluids in thermal solar technologies, and other important areas. Demonstrating stable colloidal systems in such media and understanding the factors that govern stability may open up opportunities to design new types of composites using a rich toolbox of techniques from colloidal chemistry. A comprehensive education and outreach program accompanies this research and focuses on education enrichment for the underrepresented African-American and Hispanic K-12 populations on Chicago's South Side. This project supports the continued development and distribution of nanoscience educational resources for the U. Chicago chemistry community as well as for K-12 students. This includes the development of a new graduate materials chemistry track at the University of Chicago and a continued successful effort to help undergraduates and high school students gain research experience. TECHNICAL SUMMARY:This project is directly relevant to the development of new colloidal systems. Nanoparticles of various transition metals, semiconductors, rare-earth, and magnetic materials form stable colloidal dispersions in various molten salts and liquid metals. The colloidal stability of nanoparticles in these media cannot be explained by traditional stabilization mechanisms. It appears that neither electrostatic nor steric repulsion can explain colloidal stability in a molten ionic salt. Given the very high charge density, electrostatic potential is screened on the sub-nm distance, making electrostatic repulsion short-ranged and inferior compared to van der Waals attraction. The absence of brush-like species at the particle surface in molten salt also rules out the possibility of classical steric stabilization. This project incorporates systematic experimental and theoretical investigations of this class of functional nanomaterials that are colloidally stabilized in molten inorganic salts and liquid metals. Specific aims of this project include the study and development of an understanding of the colloidal stabilization mechanism in molten salts and liquid metals at elevated temperatures, as well as exploration of properties and potential applications for colloidal dispersions of nanomaterials in molten salts and liquid metals.