Fluorine-free sulfonated aromatic polymers as proton exchange membranes

Junpei Miyake*, Kenji Miyatake


研究成果: Review article査読

42 被引用数 (Scopus)


The recent progress of our research on proton exchange membranes (PEMs) for fuel cell applications is reviewed. In particular, we focus on fluorine-free sulfonated aromatic polymers as alternatives to the benchmark perfluorosulfonic acid ionomer (e.g., Nafion) PEMs. Most fluorine-free sulfonated aromatic polymers require improved proton conductivity (at high temperatures and low humidity) and chemical and mechanical stability. To address these issues, a wide range of molecular structures and their sequences were investigated. First, the effect of molecular structure on the membrane properties of sulfonated multiblock copoly(arylene ether)s is discussed. We emphasize that phosphine oxide moieties might improve chemical stability; however, aromatic ether linkages in the hydrophilic block are not suitable because oxidative degradation and excess water swelling followed by mechanical failure is essentially inevitable. We then developed a novel polymer synthetic method, an intrapolymer Heck reaction, to ladderize aromatic ether linkages in the hydrophilic block. The ladderized rigid hydrophilic structure is an effective molecular design for balancing proton conductivity and mechanical stability. We then discuss two types of segmented copolymers based on the rigid hydrophilic structural design via a Ni-mediated coupling reaction; the hydrophilic structures are sulfonated phenylene and sulfonated benzophenone. We found that the traditional multiblock structure as well as any additional polar groups (e.g., ether, sulfone, ketone) in the hydrophilic sections are not necessary for improving the membrane properties that are important for fuel cell applications, such as proton conductivity and chemical and mechanical stability. The results indicate that fluorine-free aromatic PEMs are a potentially applicable class of ionomers for the next generation of proton exchange membrane fuel cells.

ジャーナルPolymer Journal
出版ステータスPublished - 2017 6月 1

ASJC Scopus subject areas

  • ポリマーおよびプラスチック
  • 材料化学


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