Nanoscale Organic Hybrid Materials (NOHMs)

非技术概述：本项目重点研究有机-无机杂化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）附着在坚硬的无机纳米结构上而制成的。它们被称为纳米级有机杂化材料（nohm），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一个杂化体。这种设计为科学探索和工程新材料提供了机会，这些材料具有不同寻常的特性组合，利用大量可用的纳米结构和聚合物来操纵物理特性和功能。本研究的研究考虑了一个特殊的nohm家族，其中电晕由锂离子导电聚合物组成。这种材料具有制造电池电解质的潜力，具有高的液体状离子电导率，可调的机械性能，以及在电池正常工作条件下的不可燃性。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，并提供大量增加的能量存储。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，该公司目前有14名员工。随着对材料的基本理解的增长，以及这种理解导致新的不可燃电解质设计，可以用作目前使用的可燃电池电解质的直接替代品，预计在该NSF奖的四年性能期内，进一步的技术发展可能会发生。nohm在多种易于理解的广泛社会利益应用（包括电池，3D打印和先进润滑油）中的灵活设计也为年轻学生（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。这些演示将教导学生将电池视为产生电能作为主要产品的化学反应器，以及应用导向特性与必须理解和控制才能实现它们的基本化学和物理过程之间的关系。技术概述：本项目重点研究纳米级有机杂化材料（nohm）的结构、组分动力学和离子传输，这种材料是通过将短聚合物链紧密地系在无机纳米结构上而产生的。NOHMs设计的一个结果是，接枝的聚合物（电晕）片段经历了一种熵吸引力，这是由片段必须均匀地填充纳米粒子核心之间的空间这一约束所产生的。目前认为，这种熵力至少造成了三种效应：(i)核心的强相关性，（ii）类似于日冕上交联的物理约束，以及（iii）在大长度尺度上抑制密度波动，这导致材料表现出与传统硬球悬浮液不同的低波矢量结构，但类似于不可压缩的分子流体。在连续长度尺度上，材料表现为柔软的玻璃状复杂流体，其中每个悬浮粒子始终携带着一部分悬浮介质。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、相邻粒子之间的电晕链的几何约束、电晕之间的熵介导的临时交联以及相关核的缓慢平移和重定向动力学对nohm物理性质的贡献，提出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、流变性和离子传输性质。这项工作还将探索nohm、nohm / nohm共混物和nohm聚合物共混物的相稳定性、动力学和离子输运。本研究旨在构建一个理解nohm输运行为和流变学的物理模型框架。

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.