Modification of nanoporous supported lyotropic liquid crystal polymer membranes by atomic layer deposition

Supported type I bicontinuous cubic (QI) lyotropic liquid crystal (LLC) polymer membranes with a 3D-interconnected porous structure and an effective pore size of 0.75 nm were modified by alumina atomic layer deposition (ALD). The ALD-modified polymer membranes have an effective pore size smaller than 0.55 nm and show promise for gas separations. With 10 cycles of alumina ALD coating, the selectivity of an ALD-modified QI-phase LLC polymer membrane for H2/N2 greatly increased from 12 to 65, while the permeance of H2 decreased ∼40%. The ALD membrane modification approach described here appears to be universal and has the potential to modify other nanoporous membranes for size-selective separation.