Engineering Smart Thermal Properties in Metal-Organic-Frameworks

这个项目将确定金属-有机框架材料中的热传递机制，以及该过程如何与材料的分子结构联系在一起。金属有机框架（mof）是最近发现的一类材料，是人类已知的最多孔的材料，因此它们正在积极开发用于关键能源应用，包括气体储存应用，如吸附制冷和车载储氢。令人惊讶的是，在这些应用中，mof的限制因素不是气体渗透到材料中的速度，而是可以去除热量的速度。mof是导热性能差的导体，其导热系数与混凝土相似。在该项目中获得的知识将使新的mof系统设计能够用于这些重要应用，并大大提高导热性。该研究将首次确定气体加载mof如何影响其导热性。除了储气应用之外，mof的开放分子结构还为特殊热性能的工程设计提供了许多令人兴奋的途径。特别是这项工作将测试外部调节导热性的机制。1947年晶体管的发明使我们能够从外部调节电导率，并导致了现代计算和今天的信息时代。找到从外部调节热导率的方法，可以让我们以全新的方式利用热量，从而带来类似的戏剧性变化。该项目有两个技术目标：(1)推进对载气mof热传输的科学和理论认识，以开发用于关键能源应用的新材料。(2)应用计算方法测试mof的热导率外部调节机制，确定mof热性能的变化是否可以用于化学识别。该研究将使用经典分子动力学（MD）模拟来确定mof在等正交家族中的热传递机制。等正交系列具有系统变化的结构，因此，综合一系列模拟将揭示结构与热性能之间的关系。模拟还将确定变形和框架相互渗透对热性能的影响。该研究将开发一种新的方法，通过计算瞬时热流中的相互关系，来阐明平衡态MD模拟的热输运过程。MD揭示的机理见解将被编入热性质的新理论描述，这将适用于其他大分子材料。

CBET 1403423GreaneyThis project will determine mechanisms of heat transport in metal-organic framework materials and how the processes are tied to the materials molecular architecture. Metal-organic frameworks (MOFs) are a recently discovered class of materials that are the most porous materials known to humanity and as such they are being aggressively developed for key energy applications involving gas storage applications such as adsorption refrigeration and vehicular hydrogen storage. Surprisingly the limiting factor for MOFs in these applications is not the rate of gas permeation into the materials but the speed with which heat can be removed. MOFs are poor thermal conductors with a thermal conductivity that is similar to concrete. The knowledge gained in this project will enable the systematic design of new MOFs for these important applications with greatly improved thermal conductivity. The research will, for the first time, determine how loading MOFs with gas affects their thermal conductivity. Beyond gas storage applications, the open molecular structure of MOFs provides a number of exciting avenues for engineering exotic thermal properties. In particular this work will test mechanisms for externally tuning the thermal conductivity. The invention of the transistor in 1947 gave us ability to externally tune electrical conductivity and led to modern computing and today's information age. Finding ways to externally tune thermal conductivity could bring about a similarly dramatic change by allowing us to use heat in entirely new ways.The project has two technical objectives: (1) Advance scientific and theoretical understanding of heat transport in gas laden MOFs to enable the development of new materials for key energy applications. (2) Apply computational methods to test mechanisms for externally tuning the thermal conductivity of MOFs and determine if changes in thermal properties of MOFs could be used for chemical recognition. The research will use classical molecular dynamics (MD) simulations to determine thermal transport mechanisms across the isoreticular family of MOFs. The isoreticular series have systematically varying structures so that taken together the battery of simulations will reveal relationships between structure and thermal properties. Simulations will also determine the effects on thermal properties from deformation and interpenetration of frameworks. The research will develop a new approach for elucidating thermal transport processes from equilibrium MD simulations by computing cross-correlations in the instantaneous heat current. The mechanistic insights revealed by MD will be codified in new theoretical descriptions of thermal properties that will be applicable to other macromolecular materials.