Differences in water sorption and proton conductivity between Nafion and SPEEK |
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| Authors: | Xuemei Wu Xiaowen Wang Gaohong He Jay Benziger |
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| Institution: | 1. State Key Laboratory of Fine Chemicals and Development Center of Membrane Science and Technology, Dalian University of Technology;2. State Key Laboratory of Advanced Technology and Materials Synthesis and Processing, Wuhan University of Technology;3. Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey |
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| 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/cm3. 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. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 1437–1445, 2011 |
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| Keywords: | conducting polymers conductive network ionomers membranes microstructure poly(ether ketones) swelling |
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