ION-TRANSPORTING COMPOSITE MEMBRANES .3. SELECTIVITY AND RATE OF ION-TRANSPORT IN NAFION-IMPREGNATED GORE-TEX MEMBRANES PREPARED BY A HIGH-TEMPERATURE SOLUTION CASTING METHOD

In a previous paper we discussed the rate of ion transport in Nation™,2 impregnated Gore-Tex (NIGT) membranes. The membranes described in this previous paper were prepared by immersing the Gore-Tex in a solution of Nafion and then allowing the solvent to evaporate at room temperature. Nafion films which are cast at room temperature show poor mechanical and transport properties. This paper describes the transport properties of NIGT membranes prepared via a high-temperature solution casting method. We have found that these high-temperature-cast NIGT membranes show better physical and mechanical properties than the low-temperature-cast NIGT investigated previously. The double diffusion-pathway model, described in the previous paper, quantitatively accounts for the transport data for the high-temperature-cast membranes. At the ca. 10% (or higher) Nafion loading level, both the high- and low-temperature-cast membranes show excellent cation permselectivity. Furthermore, these membranes show cation transport rates for Ru(NH3)6 3+ which are an order of magnitude higher than transport rates in homogeneous Nafion. © 1990, The Electrochemical Society, Inc. All rights reserved.