Ion-exchange membranes prepared using layer-by-layer polyelectrolyte deposition

Abstract Layer-by-layer polyelectrolyte adsorption in porous polymeric membranes provides a simple way to create ion-exchange sites without greatly decreasing hydraulic permeability (  PSS/poly(diallyldimethyl ammonium chloride) > PSS/poly(allylamine hydrochloride). Films terminated with a polyanion present cation-exchange sites that bind lysozyme, and the lysozyme-binding capacities of (PSS/PEI) 3 /PSS films increase with the ionic strength of the solution from which the last PSS layer is deposited. Charge screening during deposition of the terminal PSS layer gives rise to a larger number of ion-exchange sites and lysozyme binding capacities as high as 16 mg/mL of membrane. At 10% breakthrough, a stack of 3 membranes binds 3 times as much lysozyme as a single membrane, showing that stacking is an effective way to increase capacity.