Molecular structure design of polymers of intrinsic microporosity for membrane separation

Polymers of intrinsic microporosity (PIMs) combining microporosity and solution-processibility have witnessed their prosperous development in membrane separation. The rational molecular structure design of PIMs is of significant importance for tuning the pore structure of the membrane for precise separation. As an important branch of PIMs, polar groups-functionalized PIMs (PFPIMs) are endowed with high affinity to guest molecules, improved hydrophilicity, and enhanced interchain interaction, achieving more selective, specific, and stable separation. However, the development of PFPIMs has not yet been systematically summarized and critical details of chemical modification design for PFPIMs are lacking in previous reviews of PIMs. In this review, we summarize the research progress of PFPIMs, especially focusing on the various polarity functionalization modifications for preparing PFPIMs. In the meantime, we showcase the applications of PFPIM membranes including gas separation, liquid phase separation, and ion exchange or conducting in the battery. In the end, the existing challenges of PFPIM membranes are pointed out and their future development directions are outlooked.