Design and fabrication of highly selective and permeable polymer membranes

Abstract

Selective polymer membranes are one of the most promising materials to achieve large-scale and energy-efficient mass separation and energy conversion. However, their performance is subject to the selectivity–permeability trade-off. To overcome this trade-off and achieve high-performance ion separation, it is essential to fabricate thin membranes with a high density of uniformly sized nanopores with the pore size at around 1 nm. However, it has been challenging to precisely control the pore size at about 1 nm. In this Tutorial, we outline the underlying mechanism for selective ion transport through nanopores, especially the emerging mechanism as the nanopore size is tuned around 1 nm. Then, we review the recent development of the main fabrication methods of selective polymer membranes from either the top–down approach or the bottom–up approach, especially the novel techniques generating uniformly sized nanopores with nanometric or even subnanometric size. Finally, we discuss the future development of the design and fabrication of the selective polymer membranes to fulfill their potential in real applications.