Preparation and characterization of surface-sulfonated phenylsilsesquioxane–methylsilsesquioxane particles

Thermally and chemically stable proton conductors were prepared via surface-sulfonation of sol–gel-derived phenylsilsesquioxane–methylsilsesquioxane (PhSiO3/2–MeSiO3/2) particles in a range from 250 to 650 nm in diameter. MeSiO3/2 component was indispensable to improve the chemical durability against sulfonation solvent. Proton conductivity of the pelletized samples prepared using the sulfonated PhSiO3/2–MeSiO3/2 particles increased linearly with increasing the ion exchange capacity (IEC) of the particles. The mobility (μ) of proton was calculated to be 0.3 × 10− 4 cm2/V s. Porous PhSiO3/2–MeSiO3/2 particles prepared using a cationic surfactant of cetyltrimethylammonium bromide (CTAB) as a template of pores showed higher both IEC and water uptake, leading to an increase in proton conductivity to ∼ 10− 2 S/cm at 80 °C and 80% relative humidity.