Synthesis and properties of sulfonated block copolymers having fluorenyl groups for fuel-cell applications

Byungchan Bae, Kenji Miyatake*, Masahiro Watanabe

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

30 Citations (Scopus)


A series of sulfonated poly(arylene ether sulfone)s (SPEs) block copolymers containing fluorenyl groups were synthesized. Bis(4-fluorophenyl)sulfone (FPS) and 2,2-bis(4-hydroxy-3,5-dimethylpheny)propane were used as comonomers for hydrophobic blocks, whereas FPS and 9,9-bis(4-hydroxyphenyl)fluorene were used as hydrophilic blocks. Sulfonation with chlorosulfonic acid gave sulfonated block copolymers with molecular weight (M w) higher than 150 kDa. Proton conductivity of the SPE block copolymer with the ion exchange capacity (IEC) = 2.20 mequiv/g was 0.14 S/cm [80% relative humidity (RH)] and 0.02 S/cm (40% RH) at 80 °C, which is higher or comparable to that of a perfluorinated ionomer (Nafion) membrane. The longer hydrophilic and hydrophobic blocks resulted in higher water uptake and higher proton conductivity. Scanning transmission electron microscopy observation revealed that phase separation of the SPE block copolymers was more pronounced than that of the SPE random copolymers. The SPE block copolymer membranes showed higher mechanical properties than those of the random ones. With these properties, the SPE block copolymer membranes seem promising for fuel-cell applications.

Original languageEnglish
Pages (from-to)1279-1286
Number of pages8
JournalACS Applied Materials and Interfaces
Issue number6
Publication statusPublished - 2009 Jun 24
Externally publishedYes


  • block copolymers
  • fuel cells
  • ionomers
  • poly(arylene ether sulfone)s

ASJC Scopus subject areas

  • Materials Science(all)


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