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Partially Fluorinated Sulfonated Poly(ether amide) Fuel Cell Membranes: Influence of Chemical Structure on Membrane Properties
Department of Chemistry, University of Nevada Las Vegas, 4505 Maryland Parkway, Box 454003, Las Vegas, NV 89154-4003, USA
* Author to whom correspondence should be addressed.
Received: 28 November 2010; in revised form: 16 December 2010 / Accepted: 6 January 2010 / Published: 7 January 2011
Abstract: A series of fluorinated sulfonated poly (ether amide)s (SPAs) were synthesized for proton exchange membrane fuel cell applications. A polycondensation reaction of 4,4’-oxydianiline, 2-sulfoterephthalic acid monosodium salt, and tetrafluorophenylene dicarboxylic acids (terephthalic and isophthalic) or fluoroaliphatic dicarboxylic acids produced SPAs with sulfonation degrees of 80–90%. Controlling the feed ratio of the sulfonated and unsulfonated dicarboxylic acid monomers afforded random SPAs with ion exchange capacities between 1.7 and 2.2 meq/g and good solubility in polar aprotic solvents. Their structures were characterized using NMR and FT IR spectroscopies. Tough, flexible, and transparent films were obtained with dimethylsulfoxide using a solution casting method. Most SPA membranes with 90% sulfonation degree showed high proton conductivity (>100 mS/cm) at 80 °C and 100% relative humidity. Among them, two outstanding ionomers (ODA-STA-TPA-90 and ODA-STA-IPA-90) showed proton conductivity comparable to that of Nafion 117 between 40 and 80 °C. The influence of chemical structure on the membrane properties was systematically investigated by comparing the fluorinated polymers to their hydrogenated counterparts. The results suggest that the incorporation of fluorinated moieties in the polymer backbone of the membrane reduces water absorption. High molecular weight and the resulting physical entanglement of the polymers chains played a more important role in improving stability in water, however.
Keywords: fluorinated; fuel cell membrane; proton conductivity; polyamide
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MDPI and ACS Style
Chang, Y.; Lee, Y.-B.; Bae, C. Partially Fluorinated Sulfonated Poly(ether amide) Fuel Cell Membranes: Influence of Chemical Structure on Membrane Properties. Polymers 2011, 3, 222-235.
Chang Y, Lee Y-B, Bae C. Partially Fluorinated Sulfonated Poly(ether amide) Fuel Cell Membranes: Influence of Chemical Structure on Membrane Properties. Polymers. 2011; 3(1):222-235.
Chang, Ying; Lee, Yeong-Beom; Bae, Chulsung. 2011. "Partially Fluorinated Sulfonated Poly(ether amide) Fuel Cell Membranes: Influence of Chemical Structure on Membrane Properties." Polymers 3, no. 1: 222-235.