US EPA

1171404 

Journal Article 

Sorption and diffusion of methanol and water in PVDF-g-PSSA and Nafion (R) 117 polymer electrolyte membranes 

Hietala, S; Maunu, SL; Sundholm, F 

2000 

Yes 

Journal of Polymer Science. Part B, Polymer Physics
ISSN: 0887-6266 

JOHN WILEY & SONS INC 

NEW YORK 

38 

24 

3277-3284 

English 

10.1002/1099-0488(20001215)38:24<3277::AID-POLB90>3.3.CO;2-F 

WOS:000165510900009 

https://www.scopus.com/inward/record.uri?eid=2-s2.0-0034505008&doi=10.1002%2f1099-0488%2820001215%2938%3a24%3c3277%3a%3aAID-POLB90%3e3.0.CO%3b2-O&partnerID=40&md5=50f6eec17778f834a99a3be3785eeca0
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Sorption and diffusion properties of poly(vinylidene fluoride)-graft-poly-(styrene sulfonic acid) (PVDF-g-PSSA) and Nafion(R) 117 polymer electrolyte membranes were studied in water/methanol mixtures. The two types of membranes were found to have different sorption properties. The Nafion 117 membrane was found to have a maximum in-solvent uptake around 0.4 to 0.6 mole fraction of methanol, while the PVDF-g-PSSA membranes took up less solvent with increasing methanol concentration. The proton NMR spectra were recorded for membranes immersed in deuterated water/methanol mixtures. The spectra showed that the hydroxyl protons inside the membrane exhibit resonance lines different from the resonance lines of hydroxyl protons in the external solvent. The spectral features of the lines of these internal hydroxyl groups in the membranes were different in the Nafion membrane compared with the PVDF-g-PSSA membranes. Diffusion measurements with the pulsed field gradient NMR (PFG-NMR) method showed that the diffusion coefficient of the internal hydroxyl groups in the solvent immersed Nafion membrane mirrors the changes in the diffusion coefficients of hydroxyl and methyl protons in the external solvent. For the PVDF-g-PSSA membranes, a decrease in the diffusion coefficient of the internal hydroxyl protons was seen with increasing methanol concentration. These results indicate that the morphology and chemical structure of the membranes have an effect on their solvent sorption and diffusion characteristics. (C) 2000 John Wiley & Sons, Inc. 

polymer electrolyte membranes; fuel cells; methanol permeability; solvent uptake; self diffusion; NMR spectroscopy