Sulfonated Poly(aryl ether ketone)s Containing the Hexafluoroisopropylidene Diphenyl Moiety Prepared by Direct Copolymerization, as Proton Exchange Membranes for Fuel Cell Application

Abstract

A series of sulfonated poly(aryl ether ketone) (SPAEK-6F) copolymers were prepared by aromatic nucleophilic polycondensation of hexafluoroisopropylidene diphenol with 5,5′-carbonylbis(2-fluorobenzenesulfonate) and 4,4′-difluorobenzophenone (DFBP) at various molar ratios. The synthesized SPAEK-6F polymers possessed high molecular weights revealed by their high viscosity, and tough and flexible membranes were obtained by casting from DMAc solution. The sulfonate or sulfonic acid content (SC) of the polymers, expressed as a number per repeat unit of polymer, was determined by 1 H NMR spectroscopy and was in good agreement with the initial monomer ratios. The membranes exhibited increased water uptake and swelling with increasing SC and temperature. SPAEK-6F membranes with SC ranging from 0.6 to 1.14 maintained adequate mechanical strength after immersion in water at 80°C for 24 h. Fenton's reagent test revealed that the SPAEK-6F membranes had good stability to oxidation. The proton conductivities of the SPAEK-6F films increased with SC and temperature, reaching values above 3 × 10 -2 S/cm at 80°C for SC g 0.75. The tensile test indicated that the SPAEK-6F membranes with SC 0.75, 0.98, and 1.14 are tough and strong at ambient conditions. Consequently, these materials proved to be promising as proton exchange membranes and may be potentially useful for application in fuel cells operated at medium temperatures.

Aromatic Poly(ether ketone)s with Pendant Sulfonic Acid Phenyl Groups Prepared by a Mild Sulfonation Method for Proton Exchange Membranes

“…This method is regarded as one of the standard tests to gauge relative oxidative stability and to simulate accelerated fuel cell operating conditions. 43 It has been known that the oxidative attack by HO • and HOO • radicals mainly occurs in the hydrophilic domains to cause the degradation of polymer chains. It is expected that sidegroup-acid polymers have improved oxidative resistance over main-chain-substituted sulfonic acid polymers.…”

Carbon Nanotubes Supported Metal Nanoparticles for the Applications in Proton Exchange Membrane Fuel Cells (PEMFCs)

“…It can be performed by mixing CNTs with different oxidants such as HNO 3 , H 2 SO 4 , KMnO 4 , OsO 4 , HNO 3 /H 2 SO 4 , RuO 4 , K 2 Cr 2 O 7 , polyphosphoric acid, citric acid, ozone gas and H 2 O 2 (Hernadi et al, 2001;Hirsch et al, 2002;Hwang et al, 1995;Kannan et al, 2008;Kyotani et al, 2001;Mawhinney et al, 2000aMawhinney et al, , 2000b; Y.C. Xing et al, 2004;Yu et al, 1998;J. Zhang et al, 2003;Zheng et al, 2006).…”

“…Proton exchange membrane fuel cells (PEMFCs), as an important alternative energy source with great potentials for use in applications ranging from cellular phones, laptops, digital camera and other conventionally battery driven devices to long-term stationary monitoring electronics, have been extensively investigated (K. Matsumoto et al, 2009;P. Xing et al, 2004).…”

Preparation and DMFC performance of a sulfophenylated poly(arylene ether ketone) polymer electrolyte membrane

“…Good oxidative stability is one of the key parameters for PEMs to operate in fuel cell systems. The oxidative attack by HO • and HOO • radicals mainly occurs in the hydrophilic domains to cause the degradation of polymer chains, which leads to the loss of performance [19]. Sulfophenylated polymers are expected to have improved oxidative resistance over main-chainsubstituted sulfonic acid polymers [12,13,20], since the hydrophilic site is removed from the vicinity of the main chain.…”