Recent advances in separation membranes based on porous organic molecular materials

Abstract

Membrane separation technology is a highly efficient and energy saving alternative for many industrial processes. The development of high-performance membrane materials is the prerequisite and key to membrane separation application. Porous organic molecular materials are an emerging subclass of porous materials. They are composed of discrete molecules linked by weak non-covalent interactions between molecules, and can be assembled into modular structures with structural diversity. Representative examples include macrocycles, porous organic cages (POCs) and hydrogen-bonded organic frameworks (HOFs). Compared with various other porous materials, one unique feature of porous molecular materials is their good solution processability, which makes them easy to cast from solutions to form porous membranes, or to fabricate composite materials. Most porous organic molecular materials possess high thermal, chemical, and moisture stability and maintain their porosity under critical conditions, making them highly appealing candidates for diverse membrane applications. In this review, we aim to provide a summary of recent advances in the fabrication of membranes covering the most representative porous organic molecular materials. More importantly, the latest applications of these membranes in gas separation, ion separation, water treatment and desalination, and proton exchange in fuel cells are discussed and highlighted. Research challenges and future directions are also briefly discussed, devoted to providing guidance for the future design and development of high-performance separation membranes.