Novel cross-linked sulfonated poly (arylene ether ketone) membranes for direct methanol fuel cell

Water Soluble Polymers as Proton Exchange Membranes for Fuel Cells

“…However, the excessive swelling of PVA-PWA composite membranes limits their mechanical strength. For PEM applications, PVA is commonly incorporated into the PEM as a crosslinked partner via aldol condensation [60][61][62][63][64][65][66][67][68][69][70] or esterification [49,[71][72][73][74][75][76] to form a 3D network structure. Moreover, the degree of crosslinking of the PVA-based membranes has been shown to be easy to control via successive chemical treatments (aldol condensation or esterification).…”

“…To overcome this drawback, a crosslinking strategy has been employed to fabricate a DMFC membrane. However, the PVA membranes are poor proton conductors as compared with Nafion ® ; hence it is necessary to combine it with a monomer, oligomer or polymer that contains negatively charged ions (carboxylic and/or sulfonic acid groups), such as sulfosuccinic acid (SSA) [71], poly (styrene sulfonic acid-co-maleic acid) (PSSA-PMA) [72], poly (acrylic acid-co-maleic acid) (PAA-PMA) [76], p-sulfonate phenolic (s-Ph) [130], sulfonated polyhedral oligosilsesquioxane (sPOSS) [131], sulfonated poly (phthalazinone ether sulfone ketone) (SPPESK) [132], sulfonated poly (arylene ether ketone) (SPAKE) [74] or 4-formyl-1,3-benzenedisulfonic acid disodium salt (DSDSBA) [70] (Table 3; 1-9). Figure 7 illustrates the preparation of PVA-based crosslinked membranes.…”

“…Additionally, the methanol permeability of PVA/sPOSS membranes decreases significantly with increases in the sPOSS content rendering it lower than Nafion ® 117. sPOSS cages, as crosslinkers and sources of proton, can provide ion conduction paths while the hydrophobic portions of the same sPOSS cages combine to form a barrier to methanol permeation while contributing to the improved thermal stability of the membrane. Sulfonated aromatic polymers, such as sulfonated poly (phthalazinone ether sulfone ketone) (SPPESK) [132] and sulfonated poly (arylene ether ketone) bearing carboxylic acid groups (SPAEK-C) [74], have been used with PVA to modify the membrane's properties by covalent crosslinking. Gu et al [132] investigated the effect of using PVA as the crosslinker in comparison with a small molecule crosslinker comprising glycol and glycerol: the results indicated that the crosslinking of SPPSK with PVA requires a relatively lower crosslinking temperature and has a much higher stability in water (Table 4; 6).…”

“…The swelling ratio and proton conductivity of the SPPESK/PVA crosslinked membrane decreases rapidly with increasing PVA content, because of the decreasing IEC and the increasing crosslinker density. When SPPESK with a high degree of sulfonation (DS: 140 %) is incorporated with a lower content of PVA (<30 wt%) the resulting membranes have a higher proton conductivity than stable pristine SPPESK (DS: 81% [74] have also used PVA as a crosslinker incorporated into sulfonated poly (arylene ether ketone) bearing carboxylic acid groups (SPAEK-C) using thermal esterification to form a crosslinked membrane (Table 4; 7). Similar results were observed in SPAEK-C/PVA crosslinked membranes-that is the proton conductivities of these membranes decreased with increasing amounts of PVA due to the lower water uptake and lower IEC.…”

Sulfonated Polyimide Proton Exchange Membranes with Graphene Oxide show Improved Proton Conductivity, Methanol Crossover Impedance, and Mechanical Properties

“…However, these materials have some drawbacks that limit their practical application, [ 4 ] such as high methanol crossover, loss of conductivity at temperatures above 100 ºC, and high cost. Therefore, much research is currently being directed towards obtaining membranes that overcome these problems, such as synthesizing perfl uorinated membranes modifi ed with polyimides, [5][6][7][8] polybenzimidazoles, [9][10][11] poly(vinyl alcohol), [12][13][14] and poly(ether ether ketone). [15][16][17][18] In general, aromatic PEMs only reach suitable proton conductivities with high degrees of sulfonation.…”