Proton-Exchanging Electrolyte Membranes Based on Aromatic Condensation Polymers

Development of multiblock copolymers with novel hydroquinone-based hydrophilic blocks for proton exchange membrane (PEM) applications

“…Among a variety of candidates, wholly aromatic high temperature polymers have been considered to be the most promising materials [1][2][3]. The major advantages for utilizing high temperature polymers for fuel cell applications include their excellent thermal and oxidative stability, as well as the fact that they are economical and easy to produce.…”

“…This could be due to the fact that the proton conduction channels in sulfonated hydrocarbon-based materials are narrower than those of Nafion-type materials, which accounts for the significant reduction in conductivity under low humidity conditions [8,9]. A number of strategies have been used to address this problem, including (1) the partial fluorination of the aromatic polymer backbone to form a sharp phase separation [10,11], (2) the incorporation of bulky pendent groups to increase free-volume [12,13], (3) the addition of hydrophilic nano-particles to help retain water [14], and (4) the addition of heteropolyacid (HPA) [15]. Although each of these approaches was somewhat beneficial in increasing proton conductivity under low RH conditions, none of these methods could overcome important fundamental limitations.…”

Functionalized Poly(benzimidazole)s as Membrane Materials for Fuel Cells

“…[3] The basic design of a PEMFC includes a polymer electrolyte membrane sandwiched between two noncorrosive porous electrodes. [4,5] The proton-exchange membrane is the most important component of the PEMFC for charge transport. It must possess specific properties such as high ion-exchange capacity (IEC) in order to provide conductivities around 0.1 S Á cm À1 at operating temperatures and low permeability to fuel and oxidant.…”

“…[5] Numerous polymer systems have been examined for this application, all of which offer both advantages and disadvantages. [4] The current commercially available membranes based on perfluorinated polyelectrolytes (Nafion, Flemion and Dow membrane) have two major drawbacks, these being high cost and a strong dependence of the proton conducting properties on the presence of water, the latter drawback limiting their maximum operating temperature to the boiling point of water. [6][7][8][9] Full Paper New polymer electrolyte membranes for fuel cell applications were synthesized via covalent bonding of phosphonic acid (PA) onto poly(benzimidazole) (PBI).…”

Sulfonated Aromatic Polyethers Containing Pyridine Units as Electrolytes for High Temperature Fuel Cells

“…Introducing ionic groups onto the polymer backbone using sulfonated monomers is another approach that allows better control of the sulfonation degree (SD) and homogeneous distribution of ionic groups over the polymer chain. Rusanov et al reviewed the development of sulfonated polymers [9,10], while Lee et al paid special attention to sulfonated block copolymers which have advantageous properties [11]. In many cases, sulfonated aromatic polymers exhibit high proton conductivities and fulfill the required properties for fuel cell applications.…”