Modification of Nafion Membrane by Polycation in the Presemce of Lower Alyphatic Alcohols and Salt

Abstract

Significant increase of ion selectivity was observed for Nafion membranes modified by poly(diallyldimethylammonium chloride), PDADMAC, in the presence of lower aliphatic alcohols and NaCl. It was found that addition of the salt into the alcohol-containing modification solutions resulted not only in decrease of diffusional permeability towards vanadyl ions, P, but also in simultaneous two- to threefold growth of proton conductivity, σ, in comparison with the membranes modified in the alcohol-water solutions in the absence of a salt. As a result, ion selectivity of the membranes calculated as σ/P ratio was increased in ∼4 orders of magnitude as compared with pristine Nafion 112 membrane. Conceivable mechanism of the ion selectivity increasing is proposed for the membranes modified by PDADMAC in the presence of lower aliphatic alcohols and NaCl.