Shape-Controlled Synthesis of Covalent Organic Frameworks Enabled by Polymerization-Induced Phase Separation

Area of Science:

• Materials Science
• Chemistry
• Nanotechnology

Background:

• Controlling the shape and morphology of covalent organic frameworks (COFs) is crucial for their high-performance applications but remains challenging.
• Existing methods often struggle to integrate shape control with the crystallization process.

Purpose of the Study:

• To develop a general and scalable method for shape-controlled synthesis of covalent organic frameworks (COFs).
• To decouple phase separation and crystallization processes for precise morphology control.

Main Methods:

• A two-step synthesis strategy was employed, separating polymerization-induced phase separation (PIPS) from crystallization.
• This approach allows for flexible shaping of COFs into various forms, including columns, rods, and films.
• Hierarchically porous structures were constructed within the COFs.

Main Results:

• The method successfully produced crack-free COF monoliths with no powder detachment and a compressive modulus of 214 MPa.
• Synthesized COF films demonstrated good permeability and mechanical flexibility.
• The COF films are suitable for high-flow-rate flow-through adsorption and extraction of pollutants.

Conclusions:

• The study resolves the conflict between polymerization-induced phase separation (PIPS) and crystallization in COF synthesis.
• A versatile and scalable approach for producing COFs with tailored shapes, sizes, and morphologies has been established.
• This advancement facilitates the practical application of COFs in areas such as environmental remediation.