(532c) Thermal Transport in Interpenetrated Metal-Organic Frameworks

Kutay B. Sezginel, Patrick A. Asinger, Hasan Babaei, and Christopher E. Wilmer

Department of Chemical and Petroleum Engineering, University of Pittsburgh, 3700 O’Hara Street, Pittsburgh, Pennsylvania 15261, United States

Metal-organic frameworks (MOFs) are crystalline materials comprising building blocks of inorganic nodes and organic linkers. The record high surface area and porosity of MOFs led researchers to investigate using MOFs as adsorbents for gas storage applications. In practice, the usefulness of metal–organic frameworks (MOFs) for many gas storage applications depends on their ability to rapidly dissipate the heat generated during the exothermic adsorption process. MOFs can be precisely designed to have a wide variety of architectures which can allow tuning their thermal conductivity. While the focus for structure–property relationships in MOFs has expectedly been gas-uptake capacity and selectivity, limited insight exists on the thermal transport characteristics of MOFs. Investigating design principles for thermal transport in MOFs is critical for allowing these materials to reach their full potential for gas storage and separations applications

In this work, we use molecular dynamics simulations to investigate the effect of interpenetration on the thermal conductivity of MOFs. We find that the addition of a parallel thermal transport pathway yields a thermal conductivity nearly the sum of the two constituent frameworks. This relationship holds for a variety of interpenetrating MOFs with different atomic masses and a wide range of interframework interaction parameters. We show that both the strength and range of interactions between constituent frameworks play a significant role in framework mobility as well as framework coupling which can result in deviation from this relationship. We propose a simple model to predict thermal conductivity of the interpenetrated framework based on thermal conductivities of individual frameworks and an interframework interaction parameter which can account for this deviation.

We believe these results provide important insights into the gas adsorption application of interpenetrated MOFs especially for small gases such as H₂. The inclusion of additional frameworks could increase storage capacity of the gas by increasing adsorption sites and provide additional thermal transport pathways which allows the generated heat to dissipate more quickly.