UNS: Interfacial Properties of Nanoconfined Ionic Liquid

离子液体（ILs）是一类相对较新的仅由阳离子和阴离子组成的液体。典型的惰性液体的一些有用的特性是它们的低蒸气压、耐火性、优异的化学和热稳定性、宽的液体温度范围和宽的电化学窗口。鉴于这些优异的性能，il已被用于或考虑用于有机合成、催化、化学分离、燃料和太阳能电池，并且其应用范围还在不断扩大。然而，尽管有大量涉及ILs的新兴工艺，但与聚合物、电解质溶液和液晶等其他受限材料类别相比，人们对限制下ILs的界面特性（如流变性能和玻璃化转变温度）的理解仍然非常有限。拟议工作的目标是双重的：(i)获得描述il的结构、粘度和玻璃化转变温度如何依赖于约束程度（分离）的关系；（ii）获得对受限il的分子参数（如阳离子和阴离子的相对大小和形状）和受限表面性质（如表面电位和疏水性程度）在纳米约束下如何影响上述性质的基本理解。我们的主要假设是，当约束尺寸与il的德拜屏蔽长度相当时，约束玻璃转变温度偏离体玻璃转变温度。这一假设将主要用表面力仪器技术进行测试，这是一种独特的技术，可以将分子研究与中观尺度研究以及大规模研究联系起来。这项工作将首次在动态控制的纳米限制环境下直接测量il的粘度和玻璃化转变温度。从基础科学的角度来看，所提出的工作是理解约束下il的结构/性质关系的重要一步。这样的理解可能最终导致新的基本见解，以系统的方法来选择离子对，以合理设计在纳米限制环境下工作的离子对，并具有所需的物理性质。该项目将首先根据其在纳米约束下的重要界面特性，为选择理想类型的il提供关键指导。这些知识将有助于优化和设计涉及受限ILs的应用，如电池、太阳能电池和润滑剂。教育计划包括三个主要组成部分，重点是学生的研究监督、教学、指导和与项目研究组成部分的联系。这些组成部分包括(i)开发一门由PI教授的关于软物质界面现象的新研究生课程，（ii）在研究中指导代表性不足的本科生，以及（iii）向阿克伦地区的公众传播项目成果，少数民族占总人口的25%。依靠与当地高中教师建立的联系，通过由国家科学基金会资助的教育电子设备开发补助金。

#1511626Min, YounjinIonic liquids (ILs) are a relatively new class of liquids that consist only of cations and anions. Some of the useful properties of typical ILs are their negligibly low vapor pressure, fire resistance, excellent chemical and thermal stability, wide liquid temperature ranges, and wide electrochemical windows. Given these excellent properties, ILs have been used or considered for use in organic synthesis, catalysis, chemical separation, and fuel and solar cells, and their applications continue to expand. Despite a plethora of emerging processes involving ILs, however, an understanding of the interfacial properties of ILs under confinement, such as rheological properties and glass transition temperatures, remain very limited compared with that of other confined material classes, such as polymers, electrolyte solutions, and liquid crystals. The objective of the proposed work is twofold: (i) to obtain relationships describing how the structure, viscosity, and glass transition temperature of ILs depend on degree of confinement (separation) and (ii) to obtain a fundamental understanding of how the molecular parameters of confined ILs, such as the relative sizes and shapes of cations and anions and the surface properties of confining surfaces, such as surface potential and degree of hydrophobicity, affect the abovementioned properties under nanoconfinement. Our main hypothesis is that when the dimension of confinement becomes comparable to the Debye screening length of ILs, the confined glass transition temperature deviates from the bulk glass transition temperature. This hypothesis will primarily be tested with the surface forces apparatus technique, which is a unique technique that can link molecular studies to meso-scale studies and also to bulk-scale studies. This work will be first of its kind to directly measure the viscosity and glass transition temperature of ILs under dynamically controlled nanoconfined environments. From a fundamental science perspective, the proposed work represents an important step in understanding the structure/property relationships of ILs under confinement. Such an understanding may ultimately lead to new fundamental insights into a systematic method to select an ion pair(s) for the rational design of ILs operating under nanoconfined environments and with the desired physical properties. This project will first provide pivotal guidelines to select desirable types of ILs on demand on the basis of their important interfacial properties under nanoconfinement. Such knowledge will be useful to optimize and design applications involving confined ILs, such as batteries, solar cells, and lubricants. The educational plan consists of three main components that will focus on the research supervision of students, teaching, mentoring, and outreach to interface with the research components of the project. These components include the (i) development of a new graduate course on the interfacial phenomena of soft matter to be taught by the PI, (ii) mentoring of underrepresented undergraduate students in research, and (iii) dissemination of the project outcomes to the general public in the Akron area, where the minority constitutes 25% of the total population, by reliance on the connections established with local high school teachers through an educational electronic device development grant funded by NSF.