Influence of silica content in sulfonated poly(arylene ether ether ketone ketone) (SPAEEKK) hybrid membranes on properties for fuel cell application

The silica particles within the membranes were used for the purpose of blocking excessive methanol cross-over and for forming a pathway for proton transport due to water absorption onto the hydrophilic SiOH surface. The proton conductivities of H3PO4-doped membranes were somewhat higher than the un-doped (H3PO4-free) membranes due to increasing hydrophilicity of the membranes. The presence of silica particles within the organic polymer matrix, which decreases the ratio of free water to bound water due to the SiOH on the surface of silica derived from sol-gel reaction, results in hybrid membranes with reduced methanol permeability and improved proton conductivity.