The use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects,which remains challenging.Herein, we report asimple three-step method to produce COF aerogels,b ased on sol-gel transition, solvent-exchange,a nd supercritical CO 2 drying, in which 2D imine-based COF sheets link together to form hierarchical porous structures.T he resultant COF aerogel monoliths have extremely lowd ensities (ca. 0.02 gcm À3 ), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under am oderate strain (< 25-35 %) but become plastic under greater strain. Moreover,these COF aerogels maintain the micro-and meso-porosity of their constituent COFs,and show excellent absorption capacity (e.g. toluene uptake:3 2gg À1 ), with high removal efficiency (ca. 99 %). The same three-step method can be used to create functional composites of these COF aerogels with nanomaterials.

This work describes a high-yield “one-pot” green synthesis of imine-based Covalent Organic Frameworks in water, which can also be accelerated under microwave conditions.

Demand continues for processing methods to shape covalent organic frameworks (COFs) into macroscopic objects that are needed for their practical applications. Herein, a simple compression method to prepare large‐scale, free‐standing homogeneous and porous imine‐based COF‐membranes with dimensions in the centimeter range and excellent mechanical properties is reported. This method entails the compression of imine‐based COF‐aerogels, which undergo a morphological change from an elastic to plastic material. The COF‐membranes fabricated upon compression show good performances for the separation of gas mixtures of industrial interest, N2/CO2 and CH4/CO2. It is believed that the new procedure paves the way to a broader range of COF‐membranes.

No abstract

The use of covalent organic frameworks (COFs) in practical applications demands shaping them into macroscopic objects, which remains challenging. Herein, we report a simple three‐step method to produce COF aerogels, based on sol‐gel transition, solvent‐exchange, and supercritical CO2 drying, in which 2D imine‐based COF sheets link together to form hierarchical porous structures. The resultant COF aerogel monoliths have extremely low densities (ca. 0.02 g cm−3), high porosity (total porosity values of ca. 99 %), and mechanically behave as elastic materials under a moderate strain (<25–35 %) but become plastic under greater strain. Moreover, these COF aerogels maintain the micro‐ and meso‐porosity of their constituent COFs, and show excellent absorption capacity (e.g. toluene uptake: 32 g g−1), with high removal efficiency (ca. 99 %). The same three‐step method can be used to create functional composites of these COF aerogels with nanomaterials.