Proton donor/acceptor copolymer brushes on sulfonated poly(ether ether ketone) membrane: An approach to construct efficient proton transfer pathway in polymer electrolyte membrane fuel cell

Abstract

Proton transfer in polymer electrolyte membrane is an essential mechanism in polymer electrolyte membrane fuel cell (PEMFC). The development of PEM mostly relies on polymer modification with proton conductive species followed by membrane casting. This brings in the random existence of conductive species in the membrane to result in a limit of conductivity. The present work proposes an alignment of conductive species, i.e., proton donor and acceptor polymer chains, on the membrane through the surface-initiated polymerization so that the proton transfer proceeds effectively and continuously. The grafting of poly(acrylic acid) (Poly(AA) and/or poly(benzimidazole acrylamide) (Poly(BImAm)) onto sulfonated poly(ether ether ketone) membrane (SPEEK) enables the polymer brush decoration on the SPEEK surface. Among various types of copolymer architecture, the statistical copolymer, i.e. SPEEK-Poly(AA63-stat-BImAm26), shows the most significant proton conductivity. The present work demonstrates a simple approach to modify the surface of PEMFC membrane with proton donor/acceptor for proton conductivity enhancement.