Supramolecular reinforcement drastically enhances thermal conductivity of interpenetrated covalent organic frameworks

Abstract

Covalent organic frameworks (COFs) are an emerging class of polymeric crystals with immense permanent porosities and large surface areas that are highly sought after for a variety of applications such...

The thermoelastic properties of monolayer covalent organic frameworks studied by machine-learning molecular dynamics

“…16 Similarly, the thermal conductivity of COFs can be effectively modulated through strain engineering. 17,18 Besides, mechanical stimuli are also inevitable in many applications of 2D materials. For instance, in the thermal catalysis applications of 2D materials, such as 2D MXenes, the operational conditions typically encompass elevated temperatures and pressures.…”

Pushing the Limits of Heat Conduction in Covalent Organic Frameworks Through High‐Throughput Screening of Their Thermal Conductivity

“…Following Evans et al's work, several studies have also unveiled that COFs can exhibit higher thermal conductivities compared to MOFs and zeolites. [25][26][27][58][59][60][61][62][63][64][65] This has mainly been attributed to the extended crystalline frameworks in COFs that are composed of strongly bonded light atoms (e.g., C, N, O, and B). In contrast, the large atomic mass mismatches associated with the nodes containing the heavy metal atoms and the linkers composed of lightmass organic molecules in MOFs can significantly impede heat conduction through additional vibrational scattering.…”

“…[38,66] With the exception of the experimental results from Evans et al, [58] insights into the thermal transport processes in COFs have mostly relied on molecular dynamics (MD) simulations. [25,26,[59][60][61][62]64,65,[67][68][69][70] Although these simulations are inherently limited by the accuracy of the force fields utilized, they nonetheless provide critical insights into qualitative trends and intrinsic vibrational scattering mechanisms dictating heat conduction in porous crystals. For instance, Giri and Hopkins have shown that gas infiltration can be used as an efficient 'knob' to tune the thermal conductivity of 2D COFs with laminar pore channels.…”

Reversible and high-contrast thermal conductivity switching in a flexible covalent organic framework possessing negative Poisson's ratio

“…24,25,33 Furthermore, in view of host–guest interactions, recently it has also been shown that the thermal conductivity of organic framework materials can be enhanced significantly via increasing the level of interpenetration. 47,48,51,52 For instance, our recent study demonstrated that a 3-fold interpenetration can lead to as much as a 6-fold increase in the room temperature thermal conductivity of COF-300. 47 This enhancement in the heat conduction efficacy was attributed to increased phonon hardening, reduced vibrational scattering at the pores, and lattice stiffening resulting from the supramolecular interactions between the individual frameworks.…”

“…47,48,51,52 For instance, our recent study demonstrated that a 3-fold interpenetration can lead to as much as a 6-fold increase in the room temperature thermal conductivity of COF-300. 47 This enhancement in the heat conduction efficacy was attributed to increased phonon hardening, reduced vibrational scattering at the pores, and lattice stiffening resulting from the supramolecular interactions between the individual frameworks. It should also be noted that along with documentation of several recent advancements in COFs that are responsive to several different external stimuli such as pH levels, metal ions, electricity, light and many others, 53 the guest-induced structural changes in COFs has most notably been shown to be very swift with response times below 200 ms. 54 Therefore, COFs hold great promise for not only high-contrast but also fast reversible thermal conductivity switching applications.…”