Nanoparticle ionic fluids: interactions and transport properties

纳米粒子离子液体：相互作用和传输特性

• 批准号: 0756516
• 负责人: Lynden Archer
• 金额: $ 31.5万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2012-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0756516&HistoricalAwards=false
• 关键词: Nanoparticle; ionic; fluids; interactions; transport

CBET-0756516ArcherIntellectual Merit: Nanoparticle-based ionic materials (NIMS) are a new class of hybrid materials recently discovered at Cornell. NIMS are created by covalent attachment of charged oligomers to the surface of nanoparticles. The charge on the oligomer is balanced by a counterion species that can vary from a compact molecular entity such as a chloride ion, to a more bulky organic species such as an Isosterate ion. Depending on the interactions between the components (core particles, attached oligomers, and associated counterions), physical properties of the materials can be tuned over a surprisingly wide range. On one end of the spectrum are materials with high core particle content, which display properties similar to glasses, stiff waxes, and gels. At the opposite extreme are systems that spontaneously form homogeneous particle-based ionic fluids, characterized by transport properties remarkably similar to simple Newtonian liquids comprised of molecular building-blocks. These nanoparticle ionic fluids resemble molecular ionic liquids in their ability to form zero vapor pressure, ?green?, solvents with high dielectric constants. Because they contain an inorganic particle core, however, a more exciting array of properties can be accessed. The proposed research uses a combination of experiment, theory, and computer simulations to understand the fundamental forces in NIMS and to determine how these forces influence their transport properties. Our preliminary studies indicate that nanoparticle ionic fluids are the first example of a system of particles of any size that can reach equilibrium without a solvent. These studies also indicate that two new types of interactions are important for understanding the stability of our fluids and for predicting their transport properties: (i) An entropic attraction force arising from attachment of the effective solvent to the core particles; and (ii) Electrostatic forces due to surface-attached, bendable dipoles on the cores.Broader Impacts: The NIMS core particle is an inorganic nanostructure. This open possibility for creating entirely new types of hybrid fluids based upon the vast library of available inorganic particle chemistries and shapes. The unique properties possible in such fluids makes them attractive for a host of applications, including high-conductivity heat-transfer liquids, inkjet printable semiconducting inks, stable electrolytes for high-temperature batteries, light-weight conformal armor for military and law-enforcement personnel, and high refractive index liquids for photolithograph. Most of these applications are inaccessible to fluids created from molecular building blocks. The proposed research is the first attempt to develop fundamental understanding of the interaction forces that control structure and properties of these types of fluids. We believe that our work will provide crucial guidance on how to select components (e.g. core particle size, shape, volume fraction, corona and counterion molecular weight, and chemistry), for the many applications targeted. Furthermore, because our fluids combine elements of colloids, polymers, and complex-fluid behavior in a single material, we believe that results from the proposed research will help expand and modernize the literature on colloidal phenomena and complex fluid flows. We believe a direct result of the range of applications that will be impacted by our materials, is that transfer of knowledge developed in the study to the classroom will be more rapid than normal for subjects in the field. The novelty of NIMS and their relevance to easily appreciated applications also provides new opportunities for attracting younger students (K-12) to science. Specifically, in collaboration with the Cornell Center for Materials Research (CCMR), we will develop demonstrations based on applications of the materials, e.g. as inkjet printable inks, conformal body armor, and high-index liquids for photolithography. Our goals for these demonstrations are to engage students at an early age to think about materials in terms of their fundamental units or building blocks, and to recognize the connection between physical properties and the forces between these units. We also believe that video demonstrations connecting flow transitions in NIMS to structural transitions revealed by scattering experiments will help advanced students appreciate relationships between transport properties of complex fluids and their interactions. We will use these video demonstrations in our undergraduate Fluid Mechanics (ChemE 323) and graduate Polymer Physics (ChemE 745) courses, and also plan to take advantage of the YouTube web portal to disseminate them to a broader audience.

CBET-0756516Archer智力优点：基于纳米粒子的离子材料（NIMS）是康奈尔大学最近发现的一类新型混合材料。 NIMS 是通过将带电低聚物共价连接到纳米粒子表面而产生的。低聚物上的电荷通过抗衡离子物种来平衡，抗衡离子物种可以从紧凑的分子实体（例如氯离子）到更大的有机物种（例如异甾酸根离子）。根据组分（核心颗粒、附着的低聚物和相关反离子）之间的相互作用，材料的物理性质可以在令人惊讶的宽范围内进行调整。一方面是具有高核心颗粒含量的材料，其表现出类似于玻璃、硬蜡和凝胶的特性。 相反的极端是自发形成均匀的基于颗粒的离子液体的系统，其传输特性与由分子构件组成的简单牛顿液体非常相似。这些纳米粒子离子液体类似于分子离子液体，能够形成零蒸气压、“绿色”、具有高介电常数的溶剂。然而，由于它们含有无机颗粒核心，因此可以获得一系列更令人兴奋的特性。拟议的研究结合了实验、理论和计算机模拟来了解 NIMS 中的基本力，并确定这些力如何影响其输运特性。我们的初步研究表明，纳米颗粒离子液体是任何尺寸的颗粒系统无需溶剂即可达到平衡的第一个例子。这些研究还表明，两种新型相互作用对于理解流体的稳定性和预测其传输特性非常重要：（i）有效溶剂附着到核心颗粒上而产生的熵吸引力；更广泛的影响：NIMS 核心颗粒是一种无机纳米结构。这种基于现有无机颗粒化学和形状的庞大库创造全新类型的混合流体的开放可能性。此类流体的独特性能使其对许多应用都具有吸引力，包括高导热性传热液体、可喷墨打印的半导体墨水、高温电池的稳定电解质、军事和执法人员的轻质保形装甲，以及用于光刻的高折射率液体。大多数这些应用是由分子构件产生的流体无法实现的。拟议的研究是对控制这些类型流体的结构和性质的相互作用力进行基本理解的首次尝试。我们相信，我们的工作将为如何为许多目标应用选择组分（例如核心粒径、形状、体积分数、电晕和反离子分子量以及化学成分）提供重要指导。此外，由于我们的流体将胶体、聚合物和复杂流体行为的元素结合在单一材料中，我们相信所提出的研究结果将有助于扩展和现代化关于胶体现象和复杂流体流动的文献。我们相信，受我们的材料影响的应用范围的直接结果是，将研究中开发的知识转移到课堂的速度将比该领域学科的正常速度更快。 NIMS 的新颖性及其与易于理解的应用程序的相关性也为吸引年轻学生（K-12）学习科学提供了新的机会。具体来说，我们将与康奈尔材料研究中心（CCMR）合作，根据材料的应用开发演示，例如如喷墨打印墨水、保形防弹衣和用于光刻的高折射率液体。我们进行这些演示的目标是让学生从小就从基本单位或构建块的角度思考材料，并认识到物理特性与这些单位之间的力之间的联系。我们还相信，将 NIMS 中的流动转变与散射实验揭示的结构转变联系起来的视频演示将帮助高级学生理解复杂流体的传输特性及其相互作用之间的关系。我们将在本科生流体力学 (ChemE 323) 和研究生高分子物理学 (ChemE 745) 课程中使用这些视频演示，并计划利用 YouTube 门户网站将它们传播给更广泛的受众。