Alternative Polymer Systems for Proton Exchange Membranes (PEMs)

Hickner, Michael A.; Ghassemi, Hossein; Kim, Yu Seung; Einsla, Brian R.; McGrath, James E.

doi:10.1021/cr020711a

Cited by 2,756 publications

(1,893 citation statements)

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“…Extensive efforts have been made to develop potential alternatives for Nafion ® in PEM application [1]. Aromatic polymers with sulfonic acid groups and their sulfonated derivatives have attracted considerable interests due to their excellent thermal and chemical stability.…”

Section: Introductionmentioning

confidence: 99%

“…As a class of promising PAEK for PEM, aromatic sulfonated poly(ether ether ketone) (SPEEK) has been widely investigated. The two main approaches to introduce sulfonic acid groups into this type of polymer are (a) the post-sulfonation of existing polymers, or (b) the direct copolymerization of sulfonated monomers [1]. The sulfonation reaction of commercial Victrex PEEK, yielding sulfonated poly(ether ether ketone), has been thoroughly investigated by various groups [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…Challenges, however, may be encountered in both the precise control of the sulfonation sites location and the degree of sulfonation (DS), resulting in a random and less-defined distribution of sulfonic acid groups along the polymer chain. Moreover, harsh reaction conditions, i.e., elevated temperatures, extended reaction time and strongly-acidic sulfonation agents, may be required for the sulfonation process, which could lead to side reactions and polymer degradation [1]. 3 Copolymers synthesized by direct copolymerization exhibit advantages in the controllability of the sulfonate content (SC) and sulfonation sites location, leading to more defined chain structures in comparison with the postsulfonation method [10].…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, a loss of conductivity occurs at elevated temperatures (above 80 o C) due to dehydration. These issues may result in a reduction of mechanical properties [13] or poor membrane electrode assembly (MEA) performance and durability [1].…”

Section: Introductionmentioning

confidence: 99%

“…This transformation is supported and elucidated by simulation 4 models and experimental results. The highly incompatible hydrophobic backbone and hydrophilic side chain constituents separate the polymer matrix into micro-phases, which lead the sulfonic acid groups to cluster into hydrophilic domains and the polymer backbone to form hydrophobic domains [1]. In some polymer systems, the composition of the membrane surface differs, sometimes dramatically, from the composition within the bulk, resulting in a material with distinct surface properties, such as wettability and adhesion.…”

Section: Introductionmentioning

confidence: 99%

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Surface orientation of hydrophilic groups in sulfonated poly(ether ether ketone) membranes

Guiver

Mighri

et al. 2013

Journal of Colloid and Interface Science

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Surface orientation of hydrophilic groups in sulfonated poly(ether ether ketone) membranes

Guiver

Mighri

et al. 2013

Journal of Colloid and Interface Science

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Fuel Cells: Proton Exchange Membranes

Devanathan

2005

Encyclopedia of Inorganic Chemistry

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Proton exchange membrane, also known as polymer electrolyte membrane, fuel cells (PEMFCs) offer the promise of efficient conversion of chemical energy of fuel, such as hydrogen or methanol, into electricity with minimal pollution. Their widespread use to power zero‐emission automobiles as part of a hydrogen economy can contribute to enhanced energy security and reduction in greenhouse gas emissions. However, the commercial viability of PEMFC technology is hindered by high cost associated with the membrane‐electrode assembly (MEA) and poor membrane durability under prolonged operation at elevated temperature. Membranes for automotive fuel cell applications need to perform well over a period comparable to the life of an automotive engine and under heavy load cycling including start‐stop cycling under subfreezing conditions. The combination of elevated temperature, changes in humidity levels, physical stresses, and harsh chemical environment contribute to membrane degradation. Perfluorinated sulfonic acid (PFSA)‐based membranes, such as Nafion ® , have been the mainstay of PEMFC technology. Their limitations, in terms of cost and poor conductivity at low hydration, have led to continuing research into membranes that have good proton conductivity at elevated temperatures above 120 °C and under low‐humidity conditions. Such membranes have the potential to avoid catalyst poisoning, simplify fuel cell design, and reduce the cost of fuel cells. Hydrocarbon‐based membranes are being developed as alternatives to PFSA membranes, but concerns about chemical and mechanical stability and durability remain. Novel anhydrous membranes based on polymer gels infused with protic ionic liquids have also been recently proposed, but considerable fundamental research is needed to understand proton transport in novel membranes and evaluate durability under fuel cell operating conditions. In order to advance this promising technology, it is essential to rationally design the next generation of PEMs on the basis of an understanding of chemistry, membrane morphology, and proton transport obtained from experiment, theory, and computer simulation.

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Ionomers

Kim

2016

Kirk-Othmer Encyclopedia of Chemical Technology

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Ionomers are polymers that contain a relatively small amount of ionic groups along the polymer chain of a low dielectric constant, which show unique physical properties, eg, two glass transition temperatures, small‐angle X‐ray scattering peak, transport, and high melt viscosity. The interactions between ionic groups are important in that they allow modification of the polymer properties by introducing the ionic groups into nonionic polymers. Ionomers have received considerable attention from both industrial and academic arenas. This article starts with a brief discussion on the ionomers, multiplets, and clusters and their glass transitions. The physical properties of various ionomers are described next, followed by a discussion on ionomer blends and on plasticization using polar, nonpolar, and amphiphilic plasticizers. Finally, selected applications of ionomers are introduced.

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Alternative Polymer Systems for Proton Exchange Membranes (PEMs)

Cited by 2,756 publications

References 103 publications

Surface orientation of hydrophilic groups in sulfonated poly(ether ether ketone) membranes

Surface orientation of hydrophilic groups in sulfonated poly(ether ether ketone) membranes

Fuel Cells: Proton Exchange Membranes

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