Covalent Organic Framework Membranes through Sequential Imine Exchange for Precise Molecular Separation

Area of Science:

• Materials Science
• Chemical Engineering
• Nanotechnology

Background:

• Covalent organic framework (COF) membranes are promising for molecular separation.
• High crystallinity is key, but intercrystalline defects limit membrane formation.

Purpose of the Study:

• To develop a novel strategy for fabricating highly crystalline, defect-free COF membranes.
• To improve membrane-formation ability and precise molecular separation capabilities.

Main Methods:

• Sequential imine exchange strategy using aromatic and aliphatic amines.
• Utilizing different energy gaps of amines for distinct crystallization and defect remedy processes.

Main Results:

• Fabrication of highly crystalline, defect-free COF membranes.
• Achieved high permeance for water and methanol, and >99.9% rejection for dyes.
• Demonstrated ultrahigh separation factor (>528) and large-scale processability (>290 cm²).

Conclusions:

• The sequential imine exchange strategy effectively addresses defects in COF membranes.
• The resulting membranes show excellent performance for precise molecular separation.
• This work presents a new pathway for practical applications of COF membranes.