(174cb) Maleic Anhydride Vapor Diffusion in Nafion Membranes

The mass transport behavior of resorcinol and maleic anhydride (MA) in protonated Nafion117 membrane are investigated. Unlike small organic molecules such as methanol or ethanol, these higher molecular weight compounds exhibit irreversible uptake. Resorcinol exhibits two-stage uptake behavior in Nafion at room temperature from ethanol solution with characteristics that depend on exposure concentrations. Small angle neutron scattering (SANS) shows that this two-stage uptake is associated with swelling of the inter-crystalline regions but not the dispersed hydrophilic phase. The resorcinol partition coefficient (ratio of membrane to solution concentration) has a value of 1.2 at this exposure. By contrast, MA transport from ambient gas at 100 C appears purely Fickian with a partition coefficient of 0.17. Unlike resorcinol, negligible variation among exposures is observed. The chemical mechanisms responsible for such contrasting behavior are discussed. Potential applications include optical detection, quantification, and sequestration of MA and other toxins with low ambient concentrations.