Nanoscale Organic Hybrid Materials (NOHMs)

非技术摘要：该项目侧重于有机-无机混合材料的基础科学和技术应用，该材料是通过将短聚合物链（电晕）连接到坚硬的无机纳米结构上而形成的。被称为纳米级有机杂化材料（NOHM），它们是有机-无机杂化材料的第一个例子，其中每个纳米级构建块本身就是杂化材料。这种设计为科学探索和工程新材料提供了机会，这些新材料具有不寻常的特性组合，可以利用现有纳米结构和聚合物的大型库来操纵物理特性和功能。本研究中的研究考虑了NOHM的一个特定家族，其中电晕由锂离子导电聚合物组成。这一关注的动机是这些材料具有创造电池电解质的潜力，这些电解质具有高的液体样离子电导率，可调的机械性能，以及在电池正常工作条件下的不易燃性。这项工作很重要，因为它将使电池能够安全地利用高能金属作为阳极，并大幅增加储存的能量。随着一家技术初创公司NOHMs Technologies的成立，这一承诺的各个方面已经实现，该公司目前拥有14名员工。预计在该NSF奖项的四年执行期内，随着对材料的基本理解的增长，以及这种理解导致新的不易燃电解质设计，可用作当前使用的易燃电池电解质的直接替代品，可能会出现进一步的技术发展。NOHM在具有广泛社会利益的多种易于理解的应用（包括电池，3D打印和高级润滑剂）中的灵活设计也为向年轻学生（K-12）介绍纳米技术提供了重要机会。该项目将通过基于电池的演示吸引这些学生和他们的老师。这些演示将旨在教导学生将电池视为化学反应器，产生电能作为主要产品，并了解面向应用的特性与必须理解和控制以实现这些特性的基本化学和物理过程之间的关系。技术概述：该项目的重点是结构，成分动力学和纳米有机杂化材料（NOHMs）的离子传输，通过将短聚合物链密集地拴系到无机纳米结构上来创建。NOHM设计的结果是接枝聚合物（冠）链段经历由链段必须均匀地填充纳米颗粒核之间的空间的约束所产生的熵吸引力。这种熵力目前被认为是负责至少三个效果：（i）强相关的核心，（ii）物理约束类似于冠上的交联，和（iii）抑制大长度尺度上的密度波动，这导致材料表现出低波矢量结构不同于传统的硬球悬浮液，但类似于不可压缩的分子流体。在连续长度尺度上，这些物质表现为柔软的玻璃状复杂流体，其中每个悬浮颗粒始终携带一部分悬浮介质。相反，在纳米尺度上，它们是颗粒状的。通过分离和研究电晕链的表面拥挤对NOHM物理性质的贡献，相邻颗粒之间电晕链的几何约束，电晕之间的熵介导的临时交联，以及相关核心的缓慢平移和重定向动力学，拟议的研究将确定电晕聚合物链之间的相互作用如何影响材料的结构，流变学和离子传输特性。这项工作还将探讨NOHMs，NOHMs/NOHMs共混物和NOHMs聚合物共混物的相稳定性，动力学和离子传输。该研究旨在构建一个物理模型框架，以了解NOHMs的传输行为和流变学。

NON-TECHNICAL SUMMARY:This project focuses on basic science and technological applications of organic-inorganic hybrid materials created by attaching short polymer chains (corona) to hard, inorganic nanostructures. Termed Nanoscale Organic Hybrid Materials (NOHMs), they are the first example of an organic-inorganic hybrid material in which each nanoscale building block is itself a hybrid. This design provides opportunities for scientific exploration and for engineering new materials with unusual combinations of properties that take advantage of the large library of available nanostructures and polymers for manipulating physical properties and function. Research in this study considers a particular family of NOHMs in which the corona is comprised of lithium-ion conducting polymers. This focus is motivated by the potential such materials hold for creating battery electrolytes with high, liquid-like ionic conductivity, tunable mechanical properties, and non-flammability under normal operating conditions for batteries. The work is important because it will enable batteries to safely utilize energetic metals as their anodes and to offer substantial increases in the amount of energy stored. Aspects of this promise have already been realized with the creation of a technology start-up company, NOHMs Technologies, which currently employs 14 persons. It is expected that further technological development may occur over the four-year performance period of this NSF award as fundamental understanding of the materials grow and as this understanding leads to new non-flammable electrolyte designs that can be used as drop-in replacements for currently used flammable battery electrolytes. The flexible design of NOHMs in multiple, easy-to-appreciate applications of broad-based societal interest (including batteries, 3D printing, and advanced lubricants) also provides important opportunities for introducing younger students (K-12) to nanotechnology. The project will engage these students and their teachers through demonstrations based on batteries. These demonstrations will be designed to teach students to think about batteries as chemical reactors that produce electrical energy as the principal product, and about the relationship between applications-oriented properties and the basic chemical and physical processes that must be understood and controlled to achieve them.TECHNICAL SUMMARY: This project focuses on structure, component dynamics, and ion transport in Nanoscale Organic Hybrid Materials (NOHMs) created by densely tethering short polymer chains to inorganic nanostructures. A consequence of the design of NOHMs is that grafted polymer (corona) segments experience an entropic attractive force created by the constraint that segments must homogeneously fill the space between nanoparticle cores. This entropic force is currently believed to be responsible for at least three effects: (i) strong correlations of the cores, (ii) physical constraints analogous to cross-links on the corona, and (iii) suppressed density fluctuations on large length-scales, which causes the materials to exhibit low-wave vector structure distinct from conventional hard-sphere suspensions, but analogous to incompressible molecular fluids. On continuum length-scales the materials behave as soft glassy complex fluids in which each suspended particle carries around a share of the suspending medium at all times. In contrast, on nanometer length scales, they are granular. By isolating and studying contributions to NOHMs physical properties from surface crowding of corona chains, geometric confinement of corona chains between neighboring particles, entropy-mediated temporary cross-links between corona, and slow translation and reorientation dynamics of correlated cores, the proposed study will determine how interactions between corona polymer chains influence structure, rheology, and ion transport properties of the materials. The work will also explore phase stability, dynamics and ion transport in NOHMs, NOHMs/NOHMs blends, and NOHMs polymer blends. The proposed study aims to construct a physical model framework for understanding NOHMs transport behaviors and rheology.