Microstructure Manipulation of Covalent Organic Frameworks (COFs)-based Membrane for Efficient Separations

Covalent organic framework(COF) membranes have exhibited great potential to become the next-generation membranes for efficient separations due to the diverse structures, ordered framework pores, tunable functionality and excellent stability. This review presents the microstructure manipulation strategies for separation performance enhancement of COF membranes in recent years. Based on the three mechanisms of molecular sieving, surface diffusion, and facilitated transport, the structural modulation methods to enhance the selectivity of COF membranes are analyzed in detail. Next, strategies of realizing ultrashort mass transfer pathways and ultralow mass transfer resistance for the permeability enhancement are elaborated. Furthermore, the framework stability in COFs, interlayer stability between COF nanosheets and interfacial stability between COF layer and substrate are discussed. Finally, we discuss the existing challenges and perspectives on the future development of COF membranes, targeting at identifying the most promising strategies and directions for the engineering of COF membranes.

Automated summary

Covalent organic framework (COF) membranes, with diverse structures, ordered framework pores, tunable functionality, and excellent stability, have shown great potential as the next-generation membranes for efficient separations. This review focuses on the microstructure manipulation strategies to enhance the separation performance of COF membranes. It analyzes the structural modulation methods to improve the selectivity of COF membranes based on three mechanisms: molecular sieving, surface diffusion, and facilitated transport. Additionally, strategies to achieve ultrashort mass transfer pathways and ultralow mass transfer resistance for enhanced permeability are discussed. The framework stability, interlayer stability, and interfacial stability in COFs are also explored. Finally, the existing challenges and future prospects for the development of COF membranes are discussed, aiming to identify the most promising strategies and directions for COF membrane engineering.