Anhydrous Proton Conductivity of Phosphoric Acid-Doped PVDF- co -HFP/PVP Blended Polymer Membranes with Nano-SiO2 and s-SiO2 Particles

Abstract

In this work, a novel proton exchange membrane (PEM) working in anhydrous conditions was successfully fabricated from a 50:50 blend of polyvinylidene fluoride-co-hexafluoropropylene (PVDF-co-HFP) and polyvinylpyrrolidone (PVP) via solution casting. Proton conductivity was enabled through hydrogen-bonding interactions between phosphoric acid (H3PO4) molecules and the carbonyl groups present in the PVP polymer structure. The results indicated that the blended polymer membranes showed a tight structure, no cracks, no agglomeration, and good flexibility. Chemical resistance was also excellent, as evidenced by the stability of these membranes during 24 h of phosphoric acid doping. The thermal stability of these membranes was investigated uniformly above 300 °C using thermogravimetric analysis (TGA). The highest proton conductivity was recorded at 130 °C, and anhydrous conditions reached 38.81 mS·cm–1. These values exhibited high compatibility with the most advanced phosphoric acid-doped polybenzimidazole membranes (around 40 mS·cm–1 at 120 °C under anhydrous conditions), serving as an alternative to Nafion 212 membranes working at around 100 °C and anhydrous operation. This is a promising research direction for developing PEMs for potential applications in high-temperature (around 100 °C to 130 °C) proton exchange membrane fuel cells (HT-PEMFCs).