Preparation and characterization of proton exchange membranes based on sulfonated poly(ether ether ketone) doped with phosphorylated mesoporous silica submicrospheres

Two kinds of phosphorylated mesoporous silica submicrospheres were prepared. The phosphoric acid groups ( PO3H2) were grafted either only on the particle outer surface (PMPS-I) or on both the outer surface and the inner pore walls (PMPS-II). All the submicrospheres exhibited a uniform particle size and possessed well-aligned one-dimensional hexahedral pores. Hybrid membranes were fabricated by directly blending silica with the sulfonated poly(ether ether ketone) (SPEEK) solutions. The hybrid membranes doped with PMPS-II exhibited higher proton conductivity compared to the ones with PMPS-I. The highest proton conductivity was 0.241 S·cm-1 at 60℃ and 100% relative humidity (RH) for the hybrid membrane with 5% (mass) of PMPS-II. The experimental results indicated that continuous proton conduction channels were advantageous for the enhancement of proton conductivity of the hybrid membranes.