Sulfonated fluorinated block copolymer containing naphthalene unit/sulfonated polyvinylidene-co-hexafluoropropylene/functionalized silicon dioxide ternary composite membrane for low-humidity fuel cell applications

A ternary composite membrane, composed of a sulfonated fluorinated block copolymer containing naphthalene unit (SFBCN), sulfonated polyvinylidene fluoride-co-hexafluoropropylene (SPVdF-HFP), and functionalized silicon dioxide (FSiO₂), was fabricated via a simple solution casting method for use as a suitable proton exchange membrane in low-humidity fuel cells. The morphological and structural characterizations verify the successful formation of the ternary composite membrane. TGA and DSC analyses revealed the suitability of the materials for fuel cell applications. The increased water uptake, IEC, and proton conductivity values with increasing hydrophilicity of membranes were obtained by thorough measurements. The fabricated ternary composite membrane containing 10 wt% FSiO₂ exhibited a superior proton conductivity (12.3 mS/cm) under dehydrated conditions (90 °C at 40% RH) over the Nafion 117 (7.8 mS/cm) membrane, while at 90 °C at 100% RH, it exhibited a comparable H⁺ conductivity (93.1 mS/cm) to Nafion 117 (112 mS/cm) membrane. [Figure not available: see fulltext.]