Fluorene-Based Poly(arylene ether sulfone)s Containing Clustered Flexible Pendant Sulfonic Acids as Proton Exchange Membranes

Abstract

A new bisphenol monomer, 9,9-bis(3,5-dimethoxy-4-hydroxyphenyl) fluorene, was synthesized and polymerized to form fluorene-based poly(arylene ether sulfone) copolymers containing tetra-methoxy groups (MPAES). After converting the methoxy group to the reactive hydroxyl group, the respective side-chain type sulfonated copolymers (SPAES) were obtained by sulfobutylation. The polymers were characterized by 1H NMR, thermogravimetric analysis (TGA), water uptake, and proton and methanol transport for fuel cell applications. These SPAES copolymers had good overall properties as polymer electrolyte membrane (PEM) materials, having high proton conductivity in the range of 0.061–0.209 and 0.146–0.365 S/cm at 30 and 80 °C (under hydrated conditions), respectively. SPAES-39 (IEC = 1.93 mequiv/g) showed higher or comparable proton conductivity than that of Nafion 117 at 50–95% RH (relative humidity). The methanol permeabilities of these membranes were in the range of 3.22 to 13.1 × 10–7 cm2/s, which is lower than Nafion (15.5 × 10–7 cm2/s). In comparison with some reported sulfonated poly(arylene ether sulfone)s containing pendent sulfophenyl groups, the present fluorene-based SPAES containing clustered flexible pendent aliphatic sulfonic acid groups displayed better properties, such as lower water uptake and higher proton conductivities. A combination of high proton conductivities, low water uptake, and low methanol permeabilities for selected SPAES indicates that they are good candidate proton exchange membrane materials for evaluation in fuel cell applications.

Hexafluoroisopropylidene based sulfonated new copolytriazoles: investigation of proton exchange membrane properties

“…This caused in the rise in IEC w from 1.52-2.09 to 1.57-2.20 meq g − 1 (Table 3) and which subsequently influences (Table 3), which indicates that the SO 3 H group was successfully intro duced in the copolymers through click polymerization. In proton exchange membranes weightbased IECs (IEC w ) values are mostly used, the volumebased IECs (IEC v ) are more important (Table 3) to find a precise comparison of water uptake between various membranes (14). Ion exchange capacity (IEC v ) is determined by the ratio of number of moles of SO 3 H groups and volume of the water absorbed in the membrane (35)(36)(37).…”

“…Therefore, many efforts have been made in order to replace these materials. Several hydro carbon basedsulfonated aromatic PEM materials, such as sulfonated poly(arylene ether sulfone)s (9)(10)(11)(12)(13)(14)(15), sulfonated poly(arylene ether ketone)s (16)(17)(18)(19), sulfonated polyimides (20)(21)(22)(23)(24)(25), sulfonated poly(benzimidazole)s (26)(27)(28), sul fonated polybenzothiazoles (29)(30)(31) and sulfonated poly triazoles (32)(33)(34)(35)(36)(37), have been developed in the recent years. It is well known, that the hydrocarbonbased sulfonated aromatic copolymers display lower proton conductivity in comparison to the perfluoro sulfonated polymers, due to poor phase separation between the hydrophilic and hydrophobic domains and the weak acidic nature of SO 3 H group (38).…”

Multiblock copolymers based on poly(p-phenylene)-co-poly(arylene ether sulfone ketone) with sulfonated multiphenyl pendant groups for polymer electrolyte fuel cell (PEMFC) application

“…Sulfone and ketone groups were introduced in hydrophobic block in order to ward off electrophilic substitution attack of sulfonic acid group by improving electron deficient property of hydrophobic chain. Moreover, sulfonated multiphenyl pendant side groups were introduced in order to improve the solubility and nanophase separation between the hydrophilic sulfonic acid-containing regions and the hydrophobic polymer main chain [21,22]. The physical properties, morphology, and PEMFC performance of these polymers is presented herein.…”

Synthesis of new fluorene-based poly(aryl ether) containing pendant tert-butyl groups for low dielectric materials

“…Fluorene-based poly(aryl ether)s are a class of important functional polymers, which have potential application in microelectronic devices, gas separation, fuel cell, and so on [23][24][25][26][27]. They were mainly prepared by fluorene-based bisphenol and active aromatic dihalide.…”