Understanding Solute Diffusion and Friction in Ionic Liquids

了解离子液体中的溶质扩散和摩擦

• 批准号: 1665452
• 负责人: Mark Maroncelli
• 金额: $ 45万
• 依托单位: Pennsylvania State Univ University Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2021-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1665452&HistoricalAwards=false
• 关键词: Understanding; Solute; Diffusion; Friction; Ionic

This project, led by Professor Mark Maroncelli at Penn State and funded by the Chemical Structure Dynamics and Mechanism (CSDM-A) program of the Chemistry Division, seeks to develop a fundamental understanding of molecular motion in an emerging class of liquid media known as room temperature ionic liquids (also called ionic liquids), which hold considerable promise in a number of areas of technological importance, for example as lubricants, electrolytes in batteries, and solvents for synthesis of high-value chemicals. Whereas liquids in common use today consist of neutral molecules, ionic liquids are comprised of only charged species, ions like Na+ and Cl-, the constituents of common table salt. Although the strong attraction between such small ions renders NaCl, solid except at very high temperatures, by increasing the sizes of the component ions and doing other things to inhibit solidification, one can create purely ionic materials that remain liquid at room temperature. Insufficient understanding of how to predict the basic aspects of ionic liquids important in these applications, such as how quickly a solute molecule moves through a given ionic liquid, hampers their applications. Professor Maroncelli and his group use a combination of experimental and theoretical tools to address this challenge by studying how the structure and dynamics of ionic liquids determine the friction experienced in molecular movements. The Penn State research team is using computer simulations, supplemented by some NMR experiments, to construct a predictive understanding of molecular transport and re-orientional dynamics in ionic liquids, in particular how these dynamics depend upon the structure of a given liquid and the chemical makeup of its ions. The first project entails molecular dynamics simulations coupled to statistical analysis of experimental data on solute diffusion in order to develop models that can be used to predict the behavior new solute - ionic liquid combinations of potential technological interest. The second project uses a combination of simulation and theory to interpret apparently anomalous results obtained when the technique positron annihilation spectroscopy (PALS) was recently applied to ionic liquids. PALS is a well-known method for measuring voids in polymeric materials, but its recent use in ionic liquids provided seemingly unrealistic results. Because void structure is central to theories of molecular transport, this project seeks to learn how to correctly interpret PALS data in ionic liquids. The final project involves simulations and NMR experiments of solute rotations in order to explore how voids change over time and how these void dynamics may influence chemical reactions.

该项目由宾夕法尼亚州立大学的Mark Maroncelli教授领导，并由化学系的化学结构动力学和机制（CSDM-A）计划资助，旨在发展对新兴的一类液体介质（称为室温离子液体）中分子运动的基本理解（也称为离子液体），其在许多具有技术重要性的领域中具有相当大的前景，例如作为润滑剂，电池中的电解质，和高价值化学品合成的溶剂。 尽管目前常用的液体由中性分子组成，但离子液体仅由带电物质组成，如Na+和Cl-，它们是普通食盐的成分。虽然这种小离子之间的强吸引力使NaCl除了在非常高的温度下之外都是固体，但是通过增加组分离子的尺寸和做其他事情来抑制固化，人们可以创造出在室温下保持液体的纯离子材料。对如何预测在这些应用中重要的离子液体的基本方面的理解不足，例如溶质分子如何快速地移动通过给定的离子液体，阻碍了它们的应用。Maroncelli教授和他的团队使用实验和理论工具相结合，通过研究离子液体的结构和动力学如何决定分子运动中所经历的摩擦来应对这一挑战。宾夕法尼亚州立大学的研究小组正在使用计算机模拟，辅以一些NMR实验，以构建对离子液体中分子传输和重定向动力学的预测性理解，特别是这些动力学如何取决于给定液体的结构及其离子的化学组成。第一个项目需要分子动力学模拟，结合溶质扩散实验数据的统计分析，以开发可用于预测潜在技术利益的新溶质-离子液体组合行为的模型。第二个项目使用模拟和理论相结合，解释明显异常的结果时，正电子湮没光谱技术（帕尔斯）最近被应用于离子液体。帕尔斯是一种用于测量聚合物材料中空隙的众所周知的方法，但是其最近在离子液体中的使用提供了似乎不现实的结果。由于空隙结构是分子输运理论的核心，本项目旨在学习如何正确解释离子液体中的帕尔斯数据。最后一个项目涉及溶质旋转的模拟和NMR实验，以探索空隙如何随时间变化以及这些空隙动力学如何影响化学反应。