Sulfonated poly(styrene)s-PBIOO® blend membranes: thermo-oxidative stability and conductivity

Abstract

Low-cost polymers poly(styrene) and poly(α-methylstyrene) have been sulfonated followed by blending with PBIOO® (30 wt % sulfonated ionomer, 70 wt % PBIOO). At this polymer ratio the sulfonated ionomer served as the macromolecular acidic cross-linker which led to enhancement of the PBIOO stability. Both membrane types were treated with Fenton's Reagent to investigate their resistance to oxidation and radical attack. Indeed, the blend membranes showed enhanced stability in oxidative conditions compared to the pure PBIOO membranes. Furthermore, the sulfonated poly(α-methylstyrene)-PBIOO blend membrane showed less weight loss during and after Fenton's Test than the corresponding poly(styrene sulfonic acid)-PBIOO membrane. Assuming all the characteristics of the blend membrane before and after the Fenton's Test, we concluded for a partial degradation of both sulfonated poly(styrene)s, whereas they remain in the blend membrane matrix due to the acid-base crosslinking. Thus, since the sulfonated poly((α-methyl)styrene)-PBIOO blend membranes conserved their integrity even after Fenton's Test they can be regarded as potential low-cost high-T fuel cell membranes.