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

摘要

Sulfonated poly(arylene ether ether ketone ketone) (SPAEEKK) copolymer containing pendant sulfonic acid group (sulfonic acid content (SC)=0.67) was synthesized from commercially available monomers such as sodium 6,7-dihydroxy-2-naphthalenesulfonate (DHNS),1,3-bis(4-fluorobenzoyl)-benzene (BFBB),and hexafluorobisphenol A (6F-BPA).SPAEEKK/silica hybrid membranes were prepared using the sol-gel process under acidic conditions.The SPAEEKK/silica hybrid membranes were fabricated with different silica contents and the mem-branes were modified to achieve improved proton conductivity incorporating P-OH groups (H_3PO_4 treatment).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 ident to SiOH surface.The proton conductivities of H_3PO_4-doped membranes were somewhat higher than the un-doped (H_3PO_4-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 ident to SiOH on the surface of silica derived from sol-gel reaction,results in hybrid membranes with reduced methanol permeability and improved proton conductivity.