Letter pubs.acs.org/macroletters
Tightening Polyelectrolyte Multilayers with Oligo Pendant Ions Song Yi, William Leon, Dmitri Vezenov, and Steven L. Regen* Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania 18015, United States S Supporting Information *
ABSTRACT: A series of polycations bearing one, two, and three pendant quaternary ammonium groups per repeat unit has been synthesized and combined with poly(sodium 4-styrenesulfonate) to produce hyperthin polyelectrolyte multilayers. Incremental addition of quaternary ammonium groups per repeat unit leads to decreased permeances for H2, CO2, and N2 and increased H2/CO2 and CO2/N2 permeation selectivities. These results, together with analysis of the composition from X-ray photoelectron spectra and values of Young’s modulus from nanoindentation analysis, show that oligo pendant ions provide a means for increasing volume charge density and tightening polyelectrolyte multilayers.
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nterest in polyelectrolyte multilayers (PEMs) that are formed by sequential deposition of polyanions and polycations on solid surfaces continues to grow.1−9 Our own interest in these materials has focused, sharply, on their permeability properties.10−12 In particular, since PEMs can be readily fabricated in hyperthin (
