Preparation and Characterization of Heterogeneous PVC-Silica Proton Exchange Membrane

Heterogeneous proton exchange membranes (PEM) are synthesized using the dry phase inversion technique. The casting solutions are prepared by dispersing a finely ground cation exchange resin particle in N,N-dimethylacetamide (DMAc) solution of polyvinyl-chloride (PVC). Results show that ion exchange capacity is increased with the addition of 1 %-wt nanosilica (from 0.14 to 0.27 meq/g) while it is decreased with a higher concentration of silica. The incorporation of 0.5%-wt nanosilica improves water uptake (from 79.2% to 94.9%) and proton conductivity (from 0.02 to 0.09 mS/cm) of PEM. However, at further silica loading those properties are decreased. The membrane with 1%-wt nanosilica and 50%-wt resin showed very good stability in the oxidative environment. The post-treatment via membrane sulfonation at the optimum condition (0.1 M of sulfuric acid and 1 h reaction time) reduces the water uptake (from 94.8% to 92.3%) but improves the IEC (from 0.27 meq/g to 0.49 meg/g) and proton conductivity (from 0.02 mS/cm to 3.07 mS/cm). Meanwhile, the post-treatment via salt solution immersion at the optimum condition (0.1 M, 24 h and 30 oC) produces less water uptake (from 94.8% to 93.1%) but improves the IEC (from 0.27 meq/g to 0.55 meg/g) and drastically increases the proton conductivity (from 0.02 mS/cm to 2.79 mS/cm).