Graft-crosslinked copolymers based on poly(arylene ether ketone)-gc-sulfonated Poly(arylene ether sulfone) for PEMFC applications

摘要

Novel poly(arylene ether ketone) polymers with fluorophenyl pendants and phenoxide-terminated wholly sulfonated poly(arylene ether sulfone) oligomers are prepared via Ni(0)-catalyzed and nucleophilic polymerization, respectively, and subsequently used as starting materials to obtain graft-crosslinked membranes as polymer electrolyte membranes. The phenoxide-terminated sulfonated moieties are introduced as hydrophilic parts as well as crosslinking units. The chemical structure and morphology of the obtained membranes are confirmed by 1H NMR and tapping-mode AFM. The properties required for fuel cell applications, including water uptake and dimensional change, as well as proton conductivity, are investigated. AFM results show a clear nanoscale phase-separation microstructure of the obtained membranes. The membranes show good dimensional stability and reasonably high proton conductivities under 30-90% relative humidity. The anisotropic proton conductivity ratios (σ/||) of the membranes in water are in the range 0.65-0.92, and increase with an increase in hydrophilic block length. The results indicate that the graft-crosslinked membranes are promising candidates for applications as polymer electrolyte membranes. Novel graft-crosslinked copolymers based on poly(arylene ether ketone)-gc-sulfonated poly(arylene ether sulfone) (PAEK-gc-SPAES) were prepared and showed nano-scale phase-separation microstructure. The obtained ductile membranes exhibited anisotropic swelling, good dimensional stability as well as high proton conductivity in both in-plane and through-plane directions.