Connecting Microscopic Structures, Mesoscale Assemblies, and Macroscopic Architectures in 3D-Printed Hierarchical Porous Covalent Organic Framework Foams

Abstract

The induction of macro and mesopores into two-dimensional porous covalent organic frameworks (COFs) could enhance the exposure of the intrinsic micropores toward the pollutant environment, thereby, improving the performance. However, the challenge is to build a continuous hierarchically porous macro-architecture of crystalline organic materials in the bulk scale. In this regard, we have strategized a novel synthetic method to create hierarchically porous COF foams consisting of ordered micropores (2-2.2 nm), disordered meso and macropores (50 nm to 200 µm) as well as ordered macropores (1.5 mm to 2 cm). Herein, graphene oxide was used for creating disordered macro and meso pores in COF-GO foams. Considering the rheological features of the precursor hydrogel, we could integrate crystalline and porous COF-GO foams into self-supported 3D-printed objects with the desired shapes and sizes. Therefore, we have engineered the 3D macro-architecture of COF-GO foams into complex geometries keeping their structural order and continuous porosity intact over a range of more than a million (10 -9 m to 10 -3 m). The interconnected 3D openings in these COF-GO foams further enhance the rapid and efficient uptake of organic and inorganic pollutants from water (>95% removal within 30 s). The abundant distribution of interconnected macroporous volume (55%) throughout the COF-GO foam matrix enhances the flow of water (1.13 × 10 -3 m.s −1 ) which results in efficient mass transport and adsorption.

Nanospheres to Nanosheets: Unfolding the Morphological Influence of Microporous Organic Polymers on Micropollutants Removal

“…capacity (Qmax) of FCTPS compared to the other sulfonated HCPs was due to the hierarchical PSD and greater % of external pore volume (pore diameter > 2 nm; FCTPS: 53%, SCTPS: 47%, SKTPS: 34%. 28 The Qmax values of SKTPS and FCTPS for MEB adsorption are comparable or higher than many benchmark porous materials reported in the literature like covalent organic framework, e.g., COF-based foam, e.g., TpBD foam (194 mg g -1 ), 29 cavitand-based porous organic polymers, e.g., CalP (625 mg g -1 ), 30 hyper crosslinked polymer, e.g., THPS (330 mg g -1 ), 31 conjugated microporous polymers, e.g., CMP-YA (1016 mg g -1 ), 32 porous boron nitride nanosheets (313 mg g -1 ), 33 and 3Dactivated wood filter (198.6 mg g -1 ). 34 We performed the filtration study by packing a column bed in a Pasture pipette using SKTPS polymer (column height: 8 cm, width: 0.5 cm).…”

Covalent organic frameworks (COFs) for electrochemical applications

“…Similarly, graphene oxide (GO) was chosen as a foaming agent, successfully engineering the crystalline COF foams into 3D-printed geometrical forms, for efficient mass transport and adsorption. 100 2.2.3 Construction of COF-based electrodes. To achieve high electrochemical performance, it is critical to construct efficient and durable COF-based electrodes.…”

“…77 On the other hand, considering the low conductivity of selfstanding COF electrodes, the conducting materials (e.g. graphene, CNTs) 100 can be mixed and processed via 3D printing and Terracotta processes for constructing COF architectures with desirable shapes, sizes and conductivities.…”

Beyond Frameworks: Structuring Reticular Materials across Nano‐, Meso‐, and Bulk Regimes

“…[14] Additionally,c reating interconnected channels within am onolith significantly reduces the pressure drop (the detrimental effect of resistance to flow), thereby facilitating fast kinetics in gas storage or separation. [15] Aligning crystals on a2 -dimensional (2D) substrate with defined orientation [16] and thickness [17] can lead to the desired anisotropic properties (e.g. conductivity,permeability,optical performance).…”