Thakur Sandip, Giri Ashutosh
Department of Mechanical, Industrial, and Systems Engineering, University of Rhode Island, Kingston, RI, 02881, USA.
Small. 2024 Aug;20(32):e2401702. doi: 10.1002/smll.202401702. Epub 2024 Apr 3.
Tailor-made materials featuring large tunability in their thermal transport properties are highly sought-after for diverse applications. However, achieving `user-defined' thermal transport in a single class of material system with tunability across a wide range of thermal conductivity values requires a thorough understanding of the structure-property relationships, which has proven to be challenging. Herein, large-scale computational screening of covalent organic frameworks (COFs) for thermal conductivity is performed, providing a comprehensive understanding of their structure-property relationships by leveraging systematic atomistic simulations of 10,750 COFs with 651 distinct organic linkers. Through the data-driven approach, it is shown that by strategic modulation of their chemical and structural features, the thermal conductivity can be tuned from ultralow (≈0.02 W m K) to exceptionally high (≈50 W m K) values. It is revealed that achieving high thermal conductivity in COFs requires their assembly through carbon-carbon linkages with densities greater than 500 kg m, nominal void fractions (in the range of ≈0.6-0.9) and highly aligned polymeric chains along the heat flow direction. Following these criteria, it is shown that these flexible polymeric materials can possess exceptionally high thermal conductivities, on par with several fully dense inorganic materials. As such, the work reveals that COFs mark a new regime of materials design that combines high thermal conductivities with low densities.
具有可在其热传输特性中进行大幅调节功能的定制材料在各种应用中备受追捧。然而，要在单一类材料体系中实现“用户定义”的热传输，且热导率值能在很宽范围内调节，就需要深入理解结构-性能关系，而这已证明具有挑战性。在此，对共价有机框架（COF）进行了大规模的热导率计算筛选，通过对10750种具有651种不同有机连接体的COF进行系统的原子模拟，全面了解了它们的结构-性能关系。通过数据驱动方法表明，通过对其化学和结构特征进行策略性调节，热导率可从超低（≈0.02 W m⁻¹ K⁻¹）调节到极高（≈50 W m⁻¹ K⁻¹）的值。研究发现，要在COF中实现高导热率，需要通过密度大于500 kg m⁻³的碳-碳键进行组装，具有标称空隙率（在≈0.6 - 0.9范围内）以及沿热流方向高度排列的聚合物链。遵循这些标准表明，这些柔性聚合物材料可具有极高的热导率，与几种完全致密的无机材料相当。因此，这项工作表明COF标志着一种新的材料设计领域，它将高导热率与低密度结合在一起。
