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Acid Exfoliation of Imine‐linked Covalent Organic Frameworks Enables Solution Processing into Crystalline Thin Films
Author(s) -
Burke David W.,
Sun Chao,
Castano Ioannina,
Flanders Nathan C.,
Evans Austin M.,
Vitaku Edon,
McLeod David C.,
Lambeth Robert H.,
Chen Lin X.,
Gianneschi Nathan C.,
Dichtel William R.
Publication year - 2020
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201913975
Subject(s) - materials science , imine , chemical engineering , polymer , exfoliation joint , covalent bond , membrane , fabrication , microcrystalline , covalent organic framework , thin film , porosity , nanotechnology , organic chemistry , chemistry , crystallography , composite material , medicine , biochemistry , graphene , alternative medicine , pathology , engineering , catalysis
Covalent organic frameworks (COFs) are highly modular porous crystalline polymers that are of interest for applications such as charge‐storage devices, nanofiltration membranes, and optoelectronic devices. COFs are typically synthesized as microcrystalline powders, which limits their performance in these applications, and their limited solubility precludes large‐scale processing into more useful morphologies and devices. We report a general, scalable method to exfoliate two‐dimensional imine‐linked COF powders by temporarily protonating their linkages. The resulting suspensions were cast into continuous crystalline COF films up to 10 cm in diameter, with thicknesses ranging from 50 nm to 20 μm depending on the suspension composition, concentration, and casting protocol. Furthermore, we demonstrate that the film fabrication process proceeds through a partial depolymerization/repolymerization mechanism, providing mechanically robust films that can be easily separated from their substrates.