Perpustakaan Digital ITB
The performance of polymer-based membranes
for gas separation is currently limited by the Robeson limit,
stating that it is impossible to have high gas permeability and
high gas selectivity at the same time. We describe the
production of membranes based on the ability of graphene
oxide (GO) and poly(ethyleneimine) (PEI) multilayers to
overcome such a limit. The PEI chains act as molecular spacers
in between the GO sheets, yielding a highly reproducible,
periodic multilayered structure with a constant spacing of 3.7
nm, giving a record combination of gas permeability and
selectivity. The membranes feature a remarkable gas selectivity
(up to 500 for He/CO2), allowing to overcome the Robeson
limit. The permeability of these membranes to different gases
depends exponentially on the diameter of the gas molecule,
with a sieving mechanism never obtained in pure GO membranes, in which a size cutoff and a complex dependence on the
chemical nature of the permeant is typically observed. The tunable permeability, the high selectivity, and the possibility to
produce coatings on a wide range of polymers represent a new approach to produce gas separation membranes for large-scale
applications.