Flexible and Robust Three-Dimensional Covalent Organic Framework Membranes for Precise Separations under Extreme...

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) offer tunable properties for advanced separation membranes.
• Existing membranes face challenges in selectivity, stability, and performance under extreme conditions.

Purpose of the Study:

• To synthesize and characterize a novel 3D COF membrane for high-performance separations.
• To evaluate the membrane's selectivity, flexibility, and robustness in various conditions.
• To demonstrate post-synthetic modification for enhanced ion capture.

Main Methods:

• Synthesis of a 3D COF (3D-OH-COF) on polyimide supports.
• Fabrication of flexible and robust membranes.
• Post-synthetic conversion to a carboxyl-decorated COF (3D-COOH-COF).
• Performance testing for small molecule separation and multivalent ion capture.

Main Results:

• The 3D-OH-COF membrane exhibited excellent crystallinity, porosity, and solvent resistance.
• The membrane demonstrated sharp and durable selectivity for small molecules in water and organic solvents.
• The membrane maintained performance after severe bending and solvent soaking at elevated temperatures.
• The 3D-COOH-COF membrane showed remarkable capture ability for targeted multivalent ions.

Conclusions:

• 3D COF membranes provide a viable platform for ultimate separations under extreme conditions.
• The developed membranes offer a promising solution for challenging separation applications.
• Post-synthetic modification enables tailored functionalities for specific separation tasks.