Colloidal 2D Covalent Organic Framework-Tailored Nanofiltration Membranes for Precise Molecular Sieving

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Covalent organic frameworks (COFs) offer tunable pore sizes and ordered structures, making them promising for nanofiltration (NF) membranes.
• Traditional solvothermal synthesis yields unprocessable COF powders, hindering membrane fabrication and development.
• Developing processable COFs is crucial for advancing COF-based NF membrane technology.

Purpose of the Study:

• To synthesize processable colloidal 2D-COFs.
• To fabricate well-structured COF NF membranes using these colloidal COFs.
• To demonstrate the precise molecular sieving capabilities of the fabricated membranes.

Main Methods:

• Oil-in-water emulsion interfacial polymerization was employed to synthesize colloidal 2D-COFs.
• Layer-by-layer (LBL) assembly was utilized to construct COF NF membranes with controlled thickness and surface charge.
• The performance of the membranes was evaluated based on molecular sieving and permeance.

Main Results:

• Successfully synthesized colloidal 2D-COFs with excellent membrane-forming properties.
• Fabricated COF NF membranes exhibiting tailored thickness and surface charge.
• The developed COF NF membrane demonstrated precise sieving of dye molecules with high permeance (85 L·m^-2·h^-1·bar^-1).

Conclusions:

• A novel strategy for preparing COF NF membranes using colloidal 2D-COF LBL assembly was established.
• This approach overcomes the limitations of powder-based COFs in membrane fabrication.
• Provides a new pathway for the on-demand design and preparation of COF membranes for precise molecular sieving applications.