A 2D Soft Covalent Organic Framework Membrane Prepared via a Molecular Bridge

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Developing highly flexible and robust self-standing covalent organic framework (COF) membranes with rapid preparation is crucial for precise separation technologies.
• Existing methods face challenges in achieving both rapid synthesis and high-performance separation.

Purpose of the Study:

• To report a novel, large-area, imine-based 2D soft covalent organic framework (SCOF) membrane with rapid preparation and enhanced separation capabilities.
• To investigate the formation mechanism and performance of the SCOF membrane under various conditions.

Main Methods:

• Ingeniously selecting an aldehyde flexible linker and a trigonal building block to construct a 2D SCOF membrane.
• Utilizing a sodium dodecyl sulfate (SDS) molecular channel at the water/dichloromethane (DCM) interface for rapid membrane formation (≈5 min).
• Employing molecular dynamics (MD) simulation and density functional theory (DFT) calculation to elucidate the formation mechanism.

Main Results:

• A record-fast SCOF membrane formation achieved in approximately 5 minutes, 72 times faster than reported literature.
• The SCOF membrane exhibits a large area (226.9 cm²), uniform pores, superb sieving capability for small molecules, and excellent robustness in strong alkaline, acid, and organic solutions.
• Demonstrated sufficient flexibility with a large curvature of 2000 m⁻¹.

Conclusions:

• The novel, rapidly synthesized SCOF membrane offers a promising platform for advanced membrane-based separation science and technology.
• The dynamic SDS molecular channel facilitates efficient monomer transfer, leading to uniform pore formation and enhanced membrane properties.
• The membrane's robustness and flexibility make it suitable for demanding separation applications.