Nanoparticle ionic fluids: interactions and transport properties

CBET-0756516 Archer智力优点：基于纳米颗粒的离子材料（NIMS）是康奈尔大学最近发现的一类新的混合材料。NIMS是通过将带电的低聚物共价连接到纳米颗粒的表面而产生的。低聚物上的电荷通过抗衡物质平衡，所述抗衡物质可以从紧凑的分子实体（例如氯离子）变化到更大体积的有机物质（例如异硬脂酸根离子）。根据组分（核心颗粒、附着的低聚物和相关的抗衡离子）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节。在光谱的一端是具有高核心颗粒含量的材料，其显示类似于玻璃、硬蜡和凝胶的性质。 在另一个极端是自发形成均匀的基于粒子的离子流体的系统，其特征在于传输性质非常类似于由分子构建块组成的简单牛顿液体。这些纳米粒子离子液体类似于分子离子液体在他们的能力，形成零蒸汽压，？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，因此可以获得更令人兴奋的性能阵列。这项研究将实验、理论和计算机模拟相结合，以了解NIMS中的基本力，并确定这些力如何影响它们的传输特性。我们的初步研究表明，纳米粒子离子流体是第一个例子的任何大小的颗粒系统，可以达到平衡，没有溶剂。这些研究还表明，两种新类型的相互作用对于理解我们的流体的稳定性和预测其传输特性是重要的：（i）由有效溶剂与核心颗粒的附着引起的熵吸引力;以及（ii）由于表面附着的，可弯曲的偶极子对核心的静电力。这种开放的可能性，创造全新类型的混合流体的基础上，巨大的图书馆可用的无机颗粒化学和形状。这种液体可能具有的独特性质使其在许多应用中具有吸引力，包括高导电性传热液体，喷墨印刷半导体油墨，高温电池的稳定电解质，军事和执法人员的轻质保形装甲，以及用于照相机的高折射率液体。这些应用中的大多数都无法使用由分子构建块创建的流体。拟议的研究是第一次尝试发展控制这些类型的流体的结构和性质的相互作用力的基本理解。我们相信，我们的工作将为许多目标应用提供如何选择组件（例如核心颗粒尺寸，形状，体积分数，电晕和反电晕分子量以及化学）的关键指导。此外，由于我们的流体在单一材料中结合了胶体、聚合物和复杂流体行为的联合收割机元素，我们相信所提出的研究结果将有助于扩展和现代化有关胶体现象和复杂流体流动的文献。我们相信，将受到我们的材料影响的应用范围的直接结果是，在研究中开发的知识转移到课堂上将比该领域的正常科目更快。NIMS的新奇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。具体而言，我们将与康奈尔材料研究中心（CCMR）合作，开发基于材料应用的演示，例如喷墨打印墨水，保形防弹衣和用于光刻的高折射率液体。这些演示的目标是让学生在很小的时候就从基本单位或积木的角度思考材料，并认识到物理特性与这些单位之间的力之间的联系。我们还认为，视频演示连接流过渡NIMS散射实验揭示的结构转变，将有助于先进的学生欣赏复杂流体的传输特性和它们的相互作用之间的关系。我们将在本科流体力学（ChemE 323）和研究生高分子物理（ChemE 745）课程中使用这些视频演示，并计划利用YouTube门户网站将其传播给更广泛的受众。

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.