(128a) Analysis of the Physical and Chemical Stability of Cast Nafion® Membranes with Respect to Methanol Solubility and Radical Attack

We have recently found that the new generation cast Nafion® membranes are susceptible to disintegration/dissolution when subjected to boiling methanol. In order to mitigate this undesirable behavior, we have begun a series of investigations aimed at improving the morphology-property relationships in these cast materials. The purpose of this study is to investigate the effects of thermal annealing and solution-processing parameters on the solubility of new generation cast Nafion®. In this work, it is shown that the percent solubility decreases upon thermally annealing the film in the acid form above 175ºC or solution-processing a film around 180ºC from a high boiling point solvent. With respect to chemical stability, we have begun studies aimed at examining the effects of Fenton's Reagent on the resistance to radical attack of new generation cast Nafion®. Changes in the 19F solid-state NMR spectra of new generation Nafion® before and after chemical degradation via Fenton's Reagent predicts a rather random attack by ?OH and ?OOH radicals with slight preference for the side chain. These spectroscopic data are in agreement with measurements of the ion exchange capacity (IEC) and equivalent weight (EW) of the polymer films before and after chemical degradation.