Ordering Covalent-Organic Frameworks toward Next-Generation Nanofiltration
1Key Lab of Functional Polymers for Sustainability of Jiangsu, School of Energy and Environment, Southeast University, Nanjing, Jiangsu 211189, P. R. China.
Accounts of Chemical Research
|February 12, 2026
Summary
Covalent-organic frameworks (COFs) offer superior nanofiltration (NF) membrane performance, overcoming limitations of traditional polyamide membranes. Optimized COF structures and alignment significantly enhance selectivity and permeance for advanced separation technologies.
Area of Science:
- Materials Science
- Chemical Engineering
- Nanotechnology
Background:
- Nanofiltration (NF) membranes, crucial for water purification and chemical separations, traditionally use polyamide materials with limitations in transport path tortuosity and pore size distribution.
- Covalent-organic frameworks (COFs) present a promising alternative due to their tunable, monodisperse sub-2 nm pores, chemical stability, and potential to overcome the permeability-selectivity trade-off.
Purpose of the Study:
- To investigate the transport mechanisms in COFs using molecular dynamics simulations.
- To develop strategies for fabricating high-performance COF membranes with improved structural integrity and orientation.
- To engineer adaptive COF membranes with light-responsive properties for precise molecular sieving.
Main Methods:
- Molecular dynamics simulations to analyze COF pore structure and chemistry effects on transport.
- Controlled synthesis techniques (e.g., controlled activator release, temperature-swing synthesis) to improve COF film crystallinity and continuity.
- Vapor annealing to achieve face-on orientation of COF films for enhanced mobility and performance.
- Incorporation of azobenzene units into COF skeletons for light-induced, adaptive pore size and polarity control.
Main Results:
- Molecular dynamics revealed that ideally structured COFs exhibit water permeance 1-2 orders of magnitude higher than conventional polyamide NF membranes.
- Fabrication methods yielded highly crystallized, continuous COF films with minimized defects and grain boundaries.
- Face-on oriented COF films demonstrated sharpened rejection and enhanced permeance compared to randomly oriented films.
- Light-activated azobenzene units enabled angstrom-level regulation of pore size and intrapore polarity for smart sieving.
Conclusions:
- Optimized COF structures and film orientations are critical for achieving high-performance nanofiltration membranes.
- Adaptive COF membranes with light-responsive functionalities offer precise control over molecular and ionic transport.
- COFs hold significant potential to revolutionize nanofiltration, addressing limitations of current technologies and enabling new separation applications.
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