Defect Repair of Polyelectrolyte Bilayers Using SDS: The Action of Micelles Versus Monomers

Abstract

Defects within single, double, and triple polyelectrolyte bilayers derived from poly(sodium 4-styrenesulfonate) (PSS) and poly(diallyldimethyammonium chloride) (PDDA) have been repaired using aqueous solutions of sodium dodecyl sulfate (SDS), as evidenced by a reduction in their permeability and an increase in their permeation selectivity. In contrast to the use of monomer solutions of SDS, which were moderately effective in repairing only double and triple bilayers, micellar solutions proved highly effective for all three assemblies. Evidence for intact micelles or micellar fragments being deposited on the surface of single bilayers of PSS/PDDA has been obtained from a combination of atomic force microscopy, X-ray photoelectron spectroscopy, ellipsometry, and contact angle measurements. Observed CO 2 permeances of ca. 200 GPU and CO 2 /N 2 selectivities of ca. 30 for SDS-repaired, single bilayers of PSS/PDDA suggest that further development of such assemblies could have the practical potential for the separation of CO 2 from N 2 in the flue gas.

Creating Hyperthin Membranes for Gas Separations

“…In a proof-of-principle study, we demonstrated that simple exposure of a single bilayer of PSS/PDDA to a micellar solution of sodium dodecyl sulfate (SDS) significantly improved its selectivity. Thus, a CO 2 /N 2 selectivity of 30 along with a CO 2 permeance of 200 GPU was observed . We also showed that monomers, by themselves, were far less effective at repairing these defects.…”

“…Thus, a CO 2 /N 2 selectivity of 30 along with a CO 2 permeance of 200 GPU was observed. 17 We also showed that monomers, by themselves, were far less effective at repairing these defects.…”