Colloids in molten inorganic salts and liquid metals

非技术性总结：胶体状态在生物学、化学和材料科学中普遍存在。它提供了一种通用的方法来创建高度不相似的组分的宏观均匀组合，例如由不混溶的脂肪和水组成的牛奶。稳定不同体系中的胶体状态是许多技术过程的核心。该项目的重点是一类新的胶体系统。 初步的研究表明，胶体状态可以实现不同的纳米粒子在熔融无机盐，并可能在液态金属。液态金属和熔盐广泛用于冶金和焊接，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会为使用胶体化学中丰富的技术工具箱设计新型复合材料提供机会。一个全面的教育和推广计划伴随着这项研究，并侧重于教育丰富的代表性不足的非洲裔美国人和西班牙裔K-12人口在芝加哥的南区。该项目支持美国纳米科学教育资源的持续开发和分发。芝加哥化学社区以及K-12学生。这包括在芝加哥大学开发一个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。技术总结：该项目与新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颗粒在各种熔盐和液态金属中形成稳定的胶体分散体。纳米粒子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。看来，无论是静电还是空间排斥都不能解释熔融离子盐中的胶体稳定性。考虑到非常高的电荷密度，静电势在亚nm距离上被屏蔽，使得静电排斥短程并且比货车德瓦尔斯吸引力差。在熔融盐中的颗粒表面处不存在刷状物质也排除了经典空间稳定的可能性。该项目结合了这类功能纳米材料的系统实验和理论研究，这些材料在熔融无机盐和液态金属中保持胶体稳定。 该项目的具体目标包括研究和发展对高温下熔融盐和液态金属中胶体稳定机制的理解，以及探索纳米材料在熔融盐和液态金属中的胶体分散体的性质和潜在应用。

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.