Differences in water sorption and proton conductivity between Nafion and SPEEK

Xuemei Wu, Xiaowen Wang, Gaohong He, Jay Benziger

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123 Scopus citations


Water sorption, volumetric expansion, and proton conductivity of 1100 EW Nafion and 555 EW sulfonated polyetheretherketone (SPEEK) were compared as functions of water activity at 60 and 80 °C. Water sorption in Nafion occurs with a small positive volume of mixing, ∼0.005 cm3/cm 3. In contrast, water sorption in SPEEK has a large negative volume of mixing ∼-0.05 cm3/cm3. The percolation thresholds for proton conduction occur at hydrophilic volume fractions of 0.10 in Nafion and 0.30 in SPEEK. Proton conductivity increases quadratically with hydrophilic volume fraction above the percolation threshold. The different percolation thresholds suggest the hydrophilic domains in Nafion grow from lamella, whereas the hydrophilic domains in SPEEK grow from spheres.

Original languageEnglish (US)
Pages (from-to)1437-1445
Number of pages9
JournalJournal of Polymer Science, Part B: Polymer Physics
Issue number20
StatePublished - Oct 15 2011

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Physical and Theoretical Chemistry
  • Polymers and Plastics
  • Materials Chemistry


  • conducting polymers
  • conductive network
  • ionomers
  • membranes
  • microstructure
  • poly(ether ketones)
  • swelling


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