Solution-processable amorphous microporous polymers for membrane applications

The adsorption and transport of molecules or ions in the confined space of microporous materials often reveal properties not seen in either dense bulk or microporous materials. The unexpected behavior of confined polymers motivates their application in advanced technologies. While the majority of microp-orous materials consist of network/framework-type strong intermolecular connections, making the pro-cessing and roll-to-roll fabrication of these materials particularly challenging, there exists a special cate-gory of microporous polymers that are amorphous and can be solution-processed. They feature relatively weak intermolecular bond strength, low long-range order, and large free-volume elements due to frus-trated polymer chain motion. However, it remains elusive to design and synthesize solution-processable amorphous microporous organic polymers for those working in the field of membrane separations and electrochemistry. The application of membranes derived from these polymers in processes beyond gas separations is also overlooked. Thus, we review the synthetic strategies toward solution-processable amorphous microporous organic polymers (SAMOPs), with a particular focus on the characteristics and the monomer/polymer structural features of each reaction. Computation-based materials design, includ-ing computational tools are introduced that can reveal the monomer/polymer rigidity, polymer chain packing, thereby the generation of free volume elements, and the pore architecture, to facilitate the design and identification of desirable polymers. On-polymer modification methodology that can afford standing-alone membranes with functional groups for applications beyond gas separation, especially tar-geting membrane-based electrochemical devices are subsequently covered. The molecular transport/ion in the sub-1-nm space provided by solution-processable amorphous microporous organic polymers are presented and the wide range application of membranes derived from these polymers is demonstrated. Finally, challenges, perspectives, and future research directions are discussed.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

The adsorption and transport of molecules or ions in microporous materials provide unique properties. Confined polymers with special characteristics are being applied in advanced technologies. Amorphous microporous polymers with weak intermolecular bond strength, low long-range order, and large free-volume elements have potential in membrane separations and electrochemistry, but their design and synthesis remain challenging. This review focuses on the synthetic strategies of solution-processable amorphous microporous organic polymers and their characteristics. It also discusses the application of membranes derived from these polymers, computational tools for materials design, on-polymer modification methodology, and molecular transport/ion in sub-1-nm space.