Colloids in molten inorganic salts and liquid metals

非技术摘要：胶体状态在生物、化学和材料科学中普遍存在。它提供了一种从宏观上创造高度不同成分的同质组合的一般方法，例如由不相容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工艺过程的核心。本项目的重点是一类新型的胶体体系。初步研究表明，不同的纳米颗粒可以在熔融的无机盐中实现胶体状态，也可能在液态金属中实现胶体状态。液态金属和熔盐在冶金、焊接、太阳能热技术等重要领域有着广泛的应用。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打开机会。伴随这项研究的是一项全面的教育和推广计划，重点是为芝加哥南区未被充分代表的非裔美国人和西班牙裔K-12人口提供教育丰富。该项目支持为芝加哥大学化学界和K-12学生继续开发和分发纳米科学教育资源。这包括在芝加哥大学开发一个新的研究生材料化学轨道，以及继续成功地帮助本科生和高中生获得研究经验。技术概述：该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。似乎无论是静电斥力还是空间斥力都不能解释熔融离子盐中胶体的稳定性。考虑到极高的电荷密度，静电势被屏蔽在亚纳米距离上，使得静电斥力比范德华引力更短且更弱。熔盐中粒子表面没有刷状物种，也排除了经典空间稳定化的可能性。该项目结合了对这类在熔融的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对高温下熔盐和液态金属中胶体稳定机理的了解，以及探索纳米材料在熔盐和液态金属中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.