Poly(vinyl alcohol)-based polymer electrolyte membranes for direct methanol fuel cells

We have prepared polymer electrolyte membranes (PEMs) from poly(vinyl alcohol) (PVA) and modified PVA polyanion containing 2 or 4 mol% of 2-methyl-1-propanesulfonic acid (AMPS) groups as a copolymer. The PEMs of various AMPS content and cross-linking conditions were prepared to determine the effect of AMPS content and cross-linking conditions on PEM properties. Proton conductivity and permeability of methanol through the PEMs increased with increasing AMPS content, C(AMPS), and with decreasing crosslinker concentration, C(GA), because of the increase in the water content. The permeability coefficient of methanol through the PEM prepared under the conditions of C(AMPS) = 2.7 mol% and C(GA) = 0.35 vol% was about 30 times lower than that of Nafion (R) 117 under the same measurement conditions. The proton permselectivity of the PEM, which is defined as the ratio of the proton conductivity to the permeability coefficient of methanol, gave a maximum value of 66 x 10(3) S cm(-3) s. The value is about three times higher than that of Nafion (R) 117. (C) 2009 Elsevier Ltd. All rights reserved