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Covalent organic framework (COF) aerogels arehierarchically porous polymeric materials with ultrahigh specific surface area, making them attractive for wide applications such as molecular capture, adsorption, and catalysis. Previous COF aerogel studies have focused on varying their chemical structures and linkage chemistries to fine-tune material properties and functionality, most of which have reported relatively unsatisfying performance (e.g., poor mechanical strength and strain tolerance). This study describes the synthesis and characterization of COF nanocomposite aerogels, whose material properties and functionality are effectively engineered through the incorporation of reinforcing fillers/binders or functional additives. Boron nitride (BN) fillers, cross-linked poly(acrylic acid) (XPAA) binders, and gold nanoparticles (AuNps) are incorporated into 1,3,5-tris(aminophenyl)benzene-terephthaldehyde (TAPB-PDA) COF aerogel matrices to form homogeneous nanocomposite aerogels with enhanced mechanical properties and unique photothermal conversion capabilities. Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, and scanning electron microscopy results confirm the successful filler/additive inclusion into the final COF nanocomposite aerogels. Specifically, BN filler loading at ∼17 wt % relative to final COF mass doubles COF aerogel’s Young’s modulus from 11 to 22 kPa according to mechanical compression tests, with only ∼10% reduction in COF’s accessible mesopores’ surface area according to nitrogen porosimeter analyses. Meanwhile, incorporating ∼7 wt % XPAA relative to final COF mass improves the Young’s modulus to 21 kPa, while increasing the aerogel’s yield strain from 10 to 65% strain, although this leads to a ∼35% reduction in COF’s accessible mesopores’ surface area. Furthermore, photothermal AuNps are incorporated to form functional COF nanocomposite aerogels, whose overall temperature increases by 5.5 °C after 1 sun (AM1.5G, 1000 W m−2) irradiation. Overall, this study demonstrates potential routes to fabricate hierarchically porous COF nanocomposite aerogels with high specific surface area, robust mechanical stability, and unique photothermal functionality, which hold promises for applications in adsorption separation, gas storage, and photocatalysis. 

Microporous two-dimensional covalent organic framework (2D COF) membranes offer promise for gas separation applications, but their gas transport mechanism remains unclear. In this study, a TpHz 2D COF membrane supported on a macroporous nylon substrate is prepared by substrate-assisted interfacial polymerization under mild conditions. The formation of a continuous and dense thin (∼300 nm thick) TpHz layer is confirmed by scanning electron microscopy and Fourier transform infrared spectroscopy. Characterization by X-ray diffraction, grazing incidence wide-angle X-ray scattering, and N2 porosimetry qualitatively reveals the microstructures of the supported TpHz membranes, i.e., they comprise partially oriented 2D COF lamellar crystallites with moderate crystallinity in an eclipsed (AA) stacking geometry, centering the effective membrane pore size distribution at ∼1.1 nm. Single gas permeation data show that the transport of common molecular gases, including H2, He, CH4, N2, and CO2, through the synthesized TpHz membranes follows the Knudsen transport mechanism, where single gas permeance decreases with an increasing molecular weight and permeation temperature. Binary gas separation results show that in the equimolar CO2/N2 mixture, the presence of the CO2 surface flow slightly hinders the N2 flow at room temperature due to the reduced membrane channel size by the adsorbed CO2 gas layer on TpHz’s pore wall. In contrast, permeation of the equimolar CH4/N2 binary mixture does not exhibit a discernible surface flow of both gases due to their much lower gas uptake on TpHz, and their transport mechanism follows Knudsen-like behavior.