|Nanostructured polyelectrolyte bilayers deposited by Layer-by-Layer
deposition on nanoporous membranes can be selectively crosslinked to
modify the polyelectrolyte charge density and control ionic selectivity
independent of ionic conductivity. For example, the polyelectrolyte
bilayer can comprise a cationic polymer layer, such as
poly(ethyleneimine), and an anionic polymer layer, such as poly(acrylic
acid). Increasing the number of bilayers increases the cation selectivity
when the poly(ethyleneimine) layer is crosslinked with glutaraldehyde.
Crosslinking the membranes also increases the chemical and mechanical
strength of the polyelectrolyte films. This controllable and inexpensive
method can be used to create ion-selective and mechanically robust
membranes on porous supports for a wide range of applications.