Nanofiller-tuned microporous polymer molecular sieves for energy and environmental processesElectronic supplementary information (ESI) available: Methods, synthesis of polymer, molecular weight distribution of polymers, thermal analysis, XPS spectra, FTIR spectra, SEM images of membranes, XRD patterns of ZIF-8 and composites, gas sorption isotherms, and detailed data of gas transport properties. See DOI: 10.1039/c5ta09060a

Microporous polymers with molecular sieving properties are promising for a wide range of applications in gas storage, molecular separations, catalysis, and energy storage. In this study, we report highly permeable and selective molecular sieves fabricated from crosslinked polymers of intrinsic microporosity (PIMs) incorporated with highly dispersed nanoscale fillers, including nonporous inorganic nanoparticles and microporous metal-organic framework (MOF) nanocrystals. We demonstrate that the combination of covalent crosslinking of microporous polymers via controlled thermal oxidation and tunable incorporation of nanofillers results in high-performance membranes with substantially enhanced permeability and molecular sieving selectivity, as demonstrated in separation of gas molecules, for example, air separation (O 2 /N 2 ), CO 2 separation from natural gas (CH 4 ) or flue gas (CO 2 /N 2 ), and H 2 separation from N 2 and CH 4 . After ageing over two years, these nanofiller-tuned molecular sieves became more selective and less permeable but maintained permeability levels that are still two orders of magnitude higher than conventional gas separation membranes. Incorporating nanofillers into thermal-oxidatively crosslinked polymers of intrinsic microporosity (PIM-1) generates highly permeable and selective molecular sieves for gas separations.