Nanoscale Organic Hybrid Materials (NOHMs)

非技术概述：该项目专注于有机-无机杂化材料的基础科学和技术应用，这些杂化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产生的。被称为纳米级有机杂化材料(NOHMs)的它们是第一个有机-无机杂化材料的例子，其中每个纳米级的构建块本身就是一个杂化材料。这种设计为科学探索和设计具有不寻常性能组合的新材料提供了机会，这些新材料利用现有的纳米结构和聚合物的大型库来操纵物理性能和功能。这项研究考虑了一类特殊的NOHM，其中电晕由锂离子导电聚合物组成。这种关注的动机是这种材料在电池的正常操作条件下具有产生高液体状离子传导性、可调的机械性能和不可燃性的电池电解液的潜力。这项工作很重要，因为它将使电池能够安全地利用含能金属作为阳极，并大幅增加存储的能量。通过创建一家技术初创公司NOHMS Technologies已经实现了这一承诺的各个方面，该公司目前雇用了14名员工。预计在该NSF奖项的四年执行期内，随着对材料的基本了解的增长，以及随着这种了解导致可用作当前使用的易燃电池电解液的替代产品的新的不可燃电解液设计，可能会出现进一步的技术开发。NOHMS的灵活设计可应用于多种社会兴趣广泛、易于理解的应用(包括电池、3D打印和高级润滑剂)，这也为向年轻学生(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来吸引这些学生和他们的老师。这些演示旨在教导学生将电池视为以产生电能为主要产品的化学反应器，以及面向应用的特性与实现这些特性必须了解和控制的基本化学和物理过程之间的关系。技术摘要：本项目重点研究纳米级有机杂化材料(NOHMs)的结构、组分动力学和离子传输，NOHMs是通过将短聚合物链紧密连接到无机纳米结构而创建的。NOHMS设计的一个结果是，接枝的聚合物(电晕)片段受到一种熵吸引力，这是由于片段必须均匀填充纳米颗粒核心之间的空间所产生的约束。这种熵力目前被认为至少有三个效应：(I)核心的强相关性，(Ii)类似于日冕上的交联链的物理约束，以及(Iii)抑制大长度尺度上的密度波动，这使得材料呈现出不同于传统硬球悬浮的低波矢量结构，但类似于不可压缩的分子流体。在连续介质长度尺度上，材料表现为柔软的玻璃状复杂流体，其中每个悬浮颗粒始终携带一部分悬浮介质。相比之下，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、电晕之间的临时交链以及相关核的缓慢平移和重定向动力学对NOHMS物理性质的贡献，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、流变性和离子传输性质。这项工作还将探索NOHMS、NOHMS/NOHMS共混物和NOHMS聚合物共混物中的相稳定性、动力学和离子传输。这项研究旨在构建一个物理模型框架，用于理解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.