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KAIST researchers report polymer membrane with 73% complete hydrogen pathways

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KAIST researchers report polymer membrane with 73% complete hydrogen pathways

KAIST chemical engineering researchers led by Tae-Hyun Bae report a polymer membrane that forms hydrogen-selective transport pathways at the angstrom scale, in a study published in Nature Communications. The membrane, ms-oDMB-DB50, reaches a Bridge Connectivity Degree of 73 percent and improves hydrogen permeability and hydrogen/nitrogen selectivity compared with the base material DB50. The team also verifies ultramicropores smaller than 3 angstroms using a helium density-probe method.

Bridge Connectivity Metric

The KAIST team introduces the Bridge Connectivity Degree, defined as the proportion of crosslinkers connected at both ends to form complete transport pathways. The metric extends the concept of complete framework connectivity from inorganic porous materials to polymer networks. The researchers report that conventional crosslinking degree and effective crosslinking degree cannot reveal whether separation-useful pores have actually formed. The new membrane, ms-oDMB-DB50, reaches a BCD of 73 percent.

Membrane Performance

The ms-oDMB-DB50 membrane shows simultaneous gains in hydrogen permeability and hydrogen/nitrogen selectivity compared with the original DB50 polymer. Analysis identifies numerous ultramicropores smaller than 3 angstroms, a size that blocks carbon dioxide access. The researchers propose a density-probe method using helium, which is smaller than hydrogen, to experimentally verify these ultramicropores. In stability testing, the membrane operates for 100 hours without performance loss.

What's Next

Scaling the membrane to large-area modules and testing it on industrial gas mixtures beyond the reported 100 hours remain immediate technical next steps. It remains unclear whether the Bridge Connectivity Degree approach can be reproduced across other polymer systems or integrated into existing hydrogen purification units.

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KAIST researchers report polymer membrane with 73% complete hydrogen pathways