Nanoporous and Highly Thermal Conductive Thin Film of Single-Crystal Covalent Organic Frameworks Ribbons

Abstract

Nanoporous materials are widely explored as efficient adsorbents for the storage of gases and liquids as well as for effective low-dielectric materials in large-scale integrated circuits. These applications require fast heat transfer, while most nanoporous substances are thermal insulators. Here, the oriented growth of micrometer-sized single-crystal covalent organic frameworks (COFs) ribbons with nanoporous structures at an air−water interface is presented. The obtained COFs ribbons are interconnected into a continuous and purely crystalline thin film. Due to the robust connectivity among the COFs ribbons, the entire film can be easily transferred and reliably contacted with target supports. The measured thermal conductivity amounts to ∼5.31 ± 0.37 W m −1 K −1 at 305 K, which is so far the highest value for nanoporous materials. These findings provide a methodology to grow and assemble single-crystal COFs into large area ensembles for the exploration of functional properties and potentially lead to new devices with COFs thin films where both porosity and thermal conductivity are desired.

Cellulose Nanocrystals as Template for Improving the Crystallinity of Two-Dimensional Covalent Organic Framework Films

“…The COF-366 films with different amounts of CNCs showed similar Raman spectra. In the films, the characteristic peaks at 1282 cm −1 and 1672 cm −1 of the two monomers disappeared, meanwhile, the C=N bond stretching vibration at 1593 cm −1 was generated [ 34 , 35 ]. The Raman spectra demonstrated the formation of imine bonds in the Schiff reaction.…”

Emerging Flexible Thermally Conductive Films: Mechanism, Fabrication, Application

“…Recently reported pure polymer films with high intrinsic k are presented in Table 2 . One can see that the most common molecular engineering strategies to enhance the intrinsic k of polymer includes the alignment of polymer chains through stretching, the increase of degree of crystallinity with heat treatment and the improvement in the molecules interactions [ 76 , 77 ]. Atomistic simulations and numerical predictions suggested that individual crystalline PE chain exhibits extraordinary high intrinsic k , over 237 W (mK) −1 [ 31 ].…”

Synthesis of Thin Film of a Three‐Dimensional Covalent Organic Framework as Anti‐counterfeiting Label

“…[ 21 ] Some of the films, especially those gained at liquid‐containing interfaces could be readily transferred onto arbitrary substrates (including electrodes), which facilitated their integration in devices. These films have shown great promise in nanofiltration, [ 16,22 ] molecular separation, [ 18 ] photochemical sensing, [ 23 ] anion transport, [ 24 ] heat conduction, [ 25 ] and proton conduction. [ 26 ] Despite the wide development of freestanding thin films of 2D COFs, the synthesis of their 3D analogues and subsequent integration in devices remains challenging.…”