Poly(arylene ether)s Containing Superacid Groups as Proton Exchange Membranes

Abstract

A series of poly(arylene ether)s containing pendant superacid groups on fluorenyl groups were synthesized and their properties were investigated for fuel cell applications. Poly(arylene ether)s containing iodo groups were synthesized by the polymerization of 2,7-diiodo-9,9-bis(4-hydroxyphenyl)fluorene with difluorinated compounds such as decafluorobiphenyl, bis(4-fluorophenyl)sulfone, and bis(4-fluorophenyl)ketone, under nucleophilic substitution conditions. The iodo groups on the fluorenyl groups were converted to perfluorosulfonic acid groups via the Ullmann coupling reaction. The degree of perfluorosulfonation was controlled to be up to 92%, which corresponds to an ion exchange capacity (IEC) of 1.52 meq/g. The ionomers yielded flexible, ductile membranes by solution casting. The ionomer membranes exhibited a characteristic hydrophilic/hydrophobic phase separation, with small interconnected hydrophilic clusters (2-3 nm), which is similar to that of the benchmark perfluorinated membrane (Nafion). The aromatic ionomers containing superacid groups showed much higher proton conductivities than those of the conventional sulfonated aromatic ionomers with similar main chain structures. Fuel cell performance with the superacidic ionomer membranes was also tested.

Membrane Electrolytes, from Perfluorosulfonic Acid (PFSA) to Hydrocarbon Ionomers

“…The superacidified ionomer membranes showed several times higher proton conductivity than that of the typical sulfonated poly (arylene ether sulfone) ionomers with similar IEC at 80 C, 50-90 % RH. Miyatake et al have also confirmed the positive effect of superacid groups on the properties of the poly (arylene ether) ionomers [80,81]. They have synthesized poly(arylene ether)s containing pendant superacid groups on fluorenyl groups (FSPEa-c) (Fig.…”

“…Large difference in the polarity between highly sulfonated units and hydrophobic units caused the formation of defined phaseseparated structures and well-connected proton pathways. The proton conductivity of the ionomer membrane with IEC = 2.38 meq/g was comparable to that of Nafion 117 at >30 % RH, 80 C. Miyatake et al have combined two strategies in a single polymer architecture (multiblock copolymers containing sulfonic acid clusters in their hydrophilic blocks) [62]. They have successfully synthesized a series of multiblock poly(arylene ether sulfone ketone)s (SPESKs) containing fully sulfonated fluorenylidene biphenylene units (Fig.…”

Sulphonated PEEK-Azadirachta indica based Composite Membranes for PEM Fuelcells

“…The proton exchange membrane fuel cell (PEMFC) is an electrochemical energy device which has an advantage of converting chemical energy directly into electrical energy with high efficiency. It is considered to be a promising technology for future portable appliances including transportation [1][2][3][4]. The proton exchange membrane (PEM) is the key compartments of a PEMFC, PEM plays differents roles in a fuelcell which includes proton transfer and separating reactant gases from each other.…”

Behavior of ionic species in sulfonated PEI using DFT simulations: A study to determine ionic conductivity

“…New proposals are, sulfonated poly(arylene ether sulfone)s [5,6], poly(arylene ether ketone)s [7], poly(arylene ether) [8], polyimides [9e12], polyphosphazenes [13], chitosan [14], polybenzimidazoles [15] and other polymers [16,17].…”