Despite numerous studies on free-standing, mixed-matrix membranes (MMMs), the development of thin-film MMMs with high permeance is still an ongoing challenge. Here, the successful fabrication of ultra-high-permeance thin-film MMMs on a porous polymer substrate is described based on a highly porous zeolitic imidazole framework (ZIF-8) and a dual-functional imidazole-based comb copolymer. The copolymer of poly(vinyl imidazole)-poly(oxyethylene methacrylate) (PVI-POEM) is synthesized via free-radical polymerization, and it exhibits CO2-philicity, strong adhesion, and good interactions with fillers. In contrast to commercial benchmark membranes such as Pebax, the use of the PVI-POEM comb copolymer results in significant improvement in the CO2 permeance without significant loss of selectivity even at high ZIF-8 loadings and low thickness. It is attributed to the in-situ formation of inverse, asymmetric morphology of MMMs and partial infiltration of PVI-POEM chains into ZIF-8 particles. Optimization of the preparation process, such as ZIF-8 loading, substrate type, and coating layer thickness, leads to an extremely high CO2 permeance of 4474 GPU with high CO2/N2 and CO2/CH4 ideal selectivities of 32.0 and 12.4, respectively, which is far beyond the current trade-off limit for membranes. The mechanism behind the exceptionally high CO2 separation performance is delineated by exploring molecular dynamic simulation through morphology, structural, and energetic analyses.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation (NRF) of South Korea funded by the Ministry of Science and ICT, Republic of Korea (NRF- 2020K1A4A7A02095371 ) and the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant funded by the Korea government ( MOTIE ) ( 20214000000090 , Fostering human resources training in advanced hydrogen energy industry).
© 2021 Elsevier B.V.
All Science Journal Classification (ASJC) codes
- Materials Science(all)
- Physical and Theoretical Chemistry
- Filtration and Separation