Abstract
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 language | English (US) |
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Pages (from-to) | 1437-1445 |
Number of pages | 9 |
Journal | Journal of Polymer Science, Part B: Polymer Physics |
Volume | 49 |
Issue number | 20 |
DOIs | |
State | Published - Oct 15 2011 |
All Science Journal Classification (ASJC) codes
- Condensed Matter Physics
- Physical and Theoretical Chemistry
- Polymers and Plastics
- Materials Chemistry
Keywords
- conducting polymers
- conductive network
- ionomers
- membranes
- microstructure
- poly(ether ketones)
- swelling