Nafion - cold cast, thermally processed and commercial films: comparison of density, water content, and equivalent weight

摘要

Throughout the literature, the density of Nafion is taken as 1.58 g/cm~3. Here, data are presented for Nafion 1100 films under various thermal and acid treatment histories, and the value of 1.58 g/cm~3 is shown to be impercise under many conditions. The solvent volume and weight fractions are reported. The examined Nafion films include recast films with and without annealing, as well as commercial Nafion films. Films with and without acid treatment are described. Water and acetonitrile were used as solvents. The equivalent weight of unannealed cast films are not significantly different than the 1100 equivalent weight of the casting solution, while the equivalent weight of annealed films is increased to 1340. The impact of imprecise densities on calculated film thickness as well as considerations of diffusion and extraction coefficients and colligative properties are outlined.