Rahman Muhammad A, Dionne Connor Jaymes, Giri Ashutosh
Department of Mechanical, Industrial and Systems Engineering, University of Rhode Island, Kingston, Rhode Island02881, United States.
ACS Appl Mater Interfaces. 2022 May 11;14(18):21687-21695. doi: 10.1021/acsami.2c03019. Epub 2022 Apr 28.
Two-dimensional covalent organic frameworks (2D COFs) are a class of modular polymeric crystals with high porosities and large surface areas, which position them as ideal candidates for applications in gas storage and separation technologies. In this work, we study the influence of pore geometry on the anisotropic heat transfer mechanisms in 2D COFs through systematic atomistic simulations. More specifically, by studying COFs with varying pore sizes and gas densities, we demonstrate that the cross-plane thermal conductivity along the direction of the laminar pores can either be decreased due to solid-gas scattering (for COFs with relatively smaller pores that are ≲2 nm) or increased due to additional heat transfer pathways introduced by the gas adsorbates (for COFs with relatively larger pores). Our simulations on COF/methane systems reveal the intricate relationship among gas diffusivities, pore geometries, and solid-gas interactions dictating the modular thermal conductivities in these materials. Along with the understanding of the fundamental nature of gas diffusion and heat conduction in the porous framework crystals, our results can also help guide the design of efficient 2D polymeric crystals for applications with improved gas storage, catalysis, and separation capabilities.
二维共价有机框架材料（2D COFs）是一类具有高孔隙率和大表面积的模块化聚合物晶体，这使其成为气体存储和分离技术应用的理想候选材料。在这项工作中，我们通过系统的原子模拟研究了孔隙几何形状对二维共价有机框架材料中各向异性传热机制的影响。更具体地说，通过研究具有不同孔径和气体密度的共价有机框架材料，我们证明了沿层状孔隙方向的平面内热导率可能会因固气散射而降低（对于孔径相对较小，小于2纳米的共价有机框架材料），或者因气体吸附物引入的额外传热途径而增加（对于孔径相对较大的共价有机框架材料）。我们对共价有机框架材料/甲烷系统的模拟揭示了气体扩散率、孔隙几何形状和固气相互作用之间的复杂关系，这些关系决定了这些材料中的模块化热导率。除了对多孔框架晶体中气体扩散和热传导的基本性质的理解之外，我们的结果还可以帮助指导高效二维聚合物晶体的设计，以用于具有改进的气体存储、催化和分离能力的应用。
