pKa-Dependent Facilitated Transport of CO2 across Hyperthin Polyelectrolyte Multilayers.

Hyperthin (ca. 20-30 nm thick) polyelectrolyte multilayers have been fabricated that are capable of facilitated transport of CO2. These membranes were fabricated from polycations bearing pendant groups of varying basicity plus poly(sodium 4-styrenesulfonate) as a polycounterion. A strong dependency of such transport on the basicity of the pendant groups (i.e., fixed carrier sites) has been found, where pKa values in the range of ca. 5-7 appear optimal.