Ultramicroporous Covalent Organic Framework Nanosheets with Functionality Pair for Membrane C₂H₂/C₂H₄ Separation

Abstract

Gas separation efficiency of covalent organic framework (COF) membrane can be greatly elevated through precise functionalization. A pair-functionalized COF membrane of 1,3,5-triformylphloroglucinol (TP) and isoquinoline-5,8-diamine (IQD) monomers in two and three nodes is designed and synthesized. TP-IQD is crystallized in a two-dimensional structure with a pore size of 6.5 Å and a surface area of 289 m 2 g À 1 . This COF possesses NÀ O paired groups which cooperatively interact with C 2 H 2 instead of C 2 H 4 . TP-IQD nanosheets of � 10 μm in width and � 4 nm in thickness are prepared by mechanical exfoliation; they are further processed with 6FDA-ODA polymer into a hybrid membrane. High porosity and functionality pair of TP-IQD offer the membrane with significantly increased C 2 H 2 permeability and C 2 H 2 /C 2 H 4 selectivity which are 160 % and 430 % higher of pure 6FDA-ODA. The boosted performance demonstrates high efficiency of the pairfunctionality strategy for the synthesis of separation-led COFs.

Post-synthetic modifications of covalent organic frameworks (COFs) for diverse applications

“…Due to the topology and linkage diversity as well as building monomers with different sizes, reactive groups, chiral centers, and docking sites, various COFs have been constructed. 2 Due to their specific attributes, these compounds have found usage in catalysis, 3,4 sensors, [5][6][7] separation, 8,9 adsorption, [10][11][12][13] energy storage, [14][15][16] drug delivery, [17][18][19][20] and electronic devices. [21][22][23] Functional groups of COFs play a key role in these applications.…”