Spectral attributes of sub-amorphous thermal conductivity in cross-linked organic–inorganic hybrids
Spectral attributes of sub-amorphous thermal conductivity in cross-linked organic–inorganic hybrids
复制标题
交联有机无机杂化物中亚非晶热导率的光谱属性
DOI：
10.1039/d0nr02657c
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发表时间：
2020
期刊：
影响因子：
6.7
通讯作者：
Abdolhosseini Qomi, Mohammad Javad
中科院分区：
文献类型：
--
作者：
Morshedifard, Ali;Moshiri, Amir;Krakowiak, Konrad J.;Abdolhosseini Qomi, Mohammad Javad
有机-无机杂化材料在不同学科中的热管理应用日益广泛。这类材料的导热系数可以低于其组分导热系数的所谓“无定形极限”。尽管它们具有重要的技术意义，但在这些材料中，完全了解这种热导率降低的原因仍然是难以捉摸的。在本文中，我们开发了一个典型的交联型有机-无机层状体系，研究了其亚非晶态导热系数的光谱来源。首先，我们研究了模型的原子结构，发现除了聚合物链长外，层的相对漂移决定了计算层间距的减小，这与实验测量结果一致。随后，我们发现，与无机样品相比，有机交联剂的导热系数降低了40%。对振动模式的深入研究表明，这种减少是模式扩散系数降低的结果，而模式扩散系数又是有机和无机成分之间振动失配的结果。我们还发现，有机交联不影响传播模对总导热系数的贡献。我们的方法为热管理应用等多种多功能杂化纳米材料的物理信息分析和设计铺平了道路。
Organic–inorganic hybrids have found increasing applications for thermal management across various disciplines. Such materials can achieve thermal conductivities below the so-called “amorphous limit” of their constituents’ thermal conductivity. Despite their technological significance, a complete understanding of the origins of this thermal conductivity reduction remains elusive in these materials. In this paper, we develop a prototypical cross-linked organic–inorganic layered system, to investigate the spectral origins of its sub-amorphous thermal conductivity. Initially, we study the atomic structure of the model and find that besides polymer chain length, the relative drift of the layers governs the reduction in computed basal spacing, in agreement with experimental measurements. We, subsequently, find that organic cross-linking results in up to 40% reduction in thermal conductivity compared to inorganic samples. An in-depth investigation of vibrational modes reveals that this reduction is the result of reduced mode diffusivities, which in turn is a consequence of a vibrational mismatch between the organic and inorganic constituents. We also show that the contribution of propagating modes to the total thermal conductivity is not affected by organic cross-linking. Our approach paves the path toward a physics-informed analysis and design of a wide range of multifunctional hybrid nanomaterials for thermal management applications among others.