Synthesis and characterization of sulfonated poly(ether ether ketone) for proton exchange membranes

Abstract

Synthesis and characterization of sulfonated poly(ether ether ketone) for proton exchange membranes Xing, P.; Robertson, Gilles; Guiver, Michael; Mikhailenko, S.; Wang, K.; Kaliaguine, S. AbstractSeries of sulfonated poly(ether ether ketone)s (SPEEKs) were prepared by sulfonation of commercial Victrex ® and Gatone ® PEEK for a comparative study of proton exchange membranes (PEM) intended for fuel cell applications. The degree of sulfonation (DS) of the sulfonated PEEK was determined from deuterated dimethyl sulfoxide (DMSO-d 6 ) solution of the purified polymers using 1 H NMR methods. The second method using a solvent suppression technique, in which DS results were obtained directly from 1 H NMR spectra of SPEEK dissolved in sulfuric acid (non-deuterated) reaction medium was evaluated. The variation between the two methods was determined. The room temperature sulfonation of PEEK, monitored directly by second 1 H NMR method, proceeded rapidly initially, reaching DS ∼ 0.8 within 1 week, but progressed slowly thereafter. A maximum DS of 1.0 was determined after 1 month at ambient temperature (∼22• C). The thermal properties of SPEEK were characterized by means of DSC and TGA. The mass averaged molecular weights M w of both Victrex ® and Gatone ® PEEK were estimated from intrinsic viscosities measured in sulfuric acid solutions. It was verified that higher temperature (55• C) did not induce any apparent chain degradation of Victrex ® (or Gatone ® ) PEEK by M w tests. The water uptake and swelling properties of prepared films were studied and the proton conductivities at different temperatures were measured. The conductivities of the SPEEKs were found to increase with increasing DS and temperatures. The effect of film casting solvents on the conductivities is also discussed.

Acid–base blend membranes consisting of sulfonated poly(ether ether ketone) and 5-amino-benzotriazole tethered polysulfone for DMFC

“…4 compares the temperature dependence of the proton conductivity under anhydrous condition of the Nafion 115, SPEEK, and its blend membranes with various PSf-BTraz contents. It should be recognized that although the membranes were dried before the conductivity measurements, there could be residual water still associated with the sulfonic acid groups [5]. We also noticed absorption of water by the membranes during the assembling of the dried membranes for the proton conductivity measurement as indicated by an increase in the weight of the membranes after we took them out from the measurement system.…”

“…Several aromatic polymers with attached sulfonic acid groups such as sulfonated poly(ether ether ketone) (SPEEK), sulfonated polysulfone (SPSf), and sulfonated polyimide (SPI) have been widely investigated as candidates to substitute for the Nafion membrane in DMFC due to their lower cost, high thermal stability, good mechanical properties, and excellent resistance to hydrolysis and oxidation [4][5][6][7][8][9]. More importantly, the more rigid aromatic polymer backbones in these polymers could lower methanol crossover due to the smaller ionic cluster size compared to that in Nafion membrane, which has a flexible polytetrafluoroethylene (PTFE) backbone.…”

Poly(tetrafluoroethylene) reinforced sulfonated poly(ether ether ketone) membranes for vanadium redox flow battery application

“…SPEEK was prepared by direct sulfonation of PEEK (VICTREX ® ) with sulfuric acid at 70 • C for 1 h as described elsewhere [29]. The degree of sulfonation (the number of SO 3 H groups per repeating unit), as obtained by 1 H NMR is 0.73 [29].…”

Electrochemical and structural characterization of sulfonated polysulfone

“…Therefore, extensive studies have been focused on developing alternatives to these per fluorosulfonated membranes [3]. In particular, different polymers that adopt the sulfonated aromatic hydrocarbon structure have been tested, including poly(arylene ether sulfone)s [4], poly(ether ether ketone)s [5], poly(sulfide sulfone)s [6], polyimides [7], poly phosphazenes [8] and polybenzimidazoles [9].…”