Rational Design of Molecular Thermal Interfaces

技术摘要：本工作是理论与实验的紧密结合，旨在设计分子界面来调节热输运。利用现有的理论工具（如r-矩阵理论，朗格万形式和模拟）和根据本提案开发的新工具（如Fokker-Planck界面分析），我们将能够快速分析和优化分子结构的热性能，而不必求助于重复模拟。然后，我们将综合这些设计并测试它们的导热性，使用这些结果来改进我们的理论模型，从而提出改进的设计。这种迭代循环将导致热传递建模以及具有高导热性的新型复合材料的根本性进展。我们的目标是功能化碳纳米管的末端，使其Kapitsa电阻最小化，并测量其导热系数。首先，我们将醇（端基）功能化纳米管与酸性氯化物反应形成酯基。或者，胺[端基]修饰的纳米管将通过与酸氯化物（所需的端基）反应来修饰，形成酰胺键[，逐渐增加偶联基的刚度]。最后，可以使用界面合成方法将端基部分（如长链全氟烷基）选择性地直接偶联到纳米管末端。这些方法也将被修改，以将其他感兴趣的端基直接耦合到纳米管上。这些材料将被纳入精心挑选的聚合物基质，并测量其热导率。纳米管通过端基与聚合物基体的振动耦合将通过复合材料相对于使用未改性纳米管制造的复合材料的热导率增加来表示。我们将在理论和实验之间进行迭代，以研究大小，取向，排列，连通性以及与宿主材料的相互作用如何影响导热性。非技术摘要：这项工作是理论和实验之间的密切合作，旨在设计附着在分子末端的原子链，以改善它们的导热性。利用现有的理论工具和根据本提案开发的新工具，我们将能够快速优化不同分子结构如何传导热量，而不必诉诸重复模拟。然后，我们将综合这些设计并测试它们的导热性，使用这些结果来改进我们的理论模型，从而提出改进的设计。我们的目标是设计原子链，以化学方式连接到碳纳米管的末端。碳纳米管本身和许多金属一样具有导热性，但由于它们非常坚硬，很难让热量从周围介质流入它们。我们将在理论和实验之间进行迭代，以研究大小，取向，排列，连通性以及与宿主材料的相互作用如何影响导热性。将热量进出碳纳米管的阻力最小化是非常重要的。例如，聚合物复合材料可用于汽车和卡车散热器，以取代更重、更昂贵的金属部件，从而节省资金和燃料；导热性好的胶粘剂可用于航空和电子领域，以提高高温性能和降低故障率。有数百种潜在的工业应用。

Technical Abstract: This work is a close collaboration between theory and experiment to design molecular interfaces to tune thermal transport. Using current theoretical tools (e.g. R-matrix theory, Langevin formalism and simulations) and new ones developed under this proposal (e.g. Fokker-Planck analysis of interfaces), we will be able to rapidly analyze and optimize the thermal properties of molecular structures without having to resort to repeated simulations. We will then synthesize these designs and test their thermal conductivity, using these results to improve our theoretical models, which will in turn suggest improved designs. This iterative loop will lead to fundamental progress in the modeling of thermal transport as well as new composites with high thermal conductivity. Our goal is to functionalize the ends of carbon nanotubes so as to minimize their Kapitsa resistance and measure their thermal conductivity. Initially, we will react alcohol [end-group] functionalized nanotubes with acid chlorides to form ester groups. Alternatively, amine [end-group] modified nanotubes will be modified by reaction with the acid chlorides (of the desired end-groups) to form amide linkages[, progressively increasing stiffness of the coupling group]. Finally, interfacial synthetic methods can be used to directly couple end group moieties, such as long chain perfluoroalkyl groups, selectively to the nanotube ends. These methods will also be modified to couple other end groups of interest directly to the nanotubes. These materials will be incorporated into carefully chosen polymer matrices and their thermal conductivities measured. Vibrational coupling of the nanotubes, via the endgroups, to the polymer matrix will be signaled by increases in thermal conductivities of the composites relative to those made using non-modified nanotubes.We will iterate between theory and experiment to study how size, orientation, alignment, connectivity, and interactions with the host material affect thermal conductivity. Non-Technical Abstract:This work is a close collaboration between theory and experiment to design chains of atoms that will be attached to the ends of molecules in order to improve how they conduct heat. Using current theoretical tools and new ones developed under this proposal, we will be able to rapidly optimize how different molecular structures conduct heat without having to resort to repeated simulations. We will then synthesize these designs and test their thermal conductivity, using these results to improve our theoretical models, which will in turn suggest improved designs. Our goal is to design chains of atoms that would be chemically attached to the ends of carbon nanotubes. Carbon nanotubes, themselves, conduct heat as well as many metals, but because they are very stiff, it is difficult to get heat to flow into them from their surrounding medium. We will iterate between theory and experiment to study how size, orientation, alignment, connectivity, and interactions with the host material affect thermal conductivity. Minimizing the resistance to getting heat into and out of carbon nanotubes would be very important. For example, polymer composites could be used in car and truck radiators to replace heavier, costlier metallic components, saving money and fuel; adhesives that conduct heat well could be used in aviation and in electronics to improve high temperature performance and lower the rate of failure. There are hundreds of potential industrial applications.