Advanced polyimide materials: Syntheses, physical properties and applications

This article provides an up-to-date perspective on the use of anion-exchange membranes in fuel cells, electrolysers, redox flow batteries, reverse electrodialysis cells, and bioelectrochemical systems (e.g. microbial fuel cells). The aim is to highlight key concepts, misconceptions, the current state-of-the-art, technological and scientific limitations, and the future challenges (research priorities) related to the use of anion-exchange membranes in these energy technologies. All the references that the authors deemed relevant, and were available on the web by the manuscript submission date (30th April 2014), are included.

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Anion-exchange membranes in electrochemical energy systems

Recent development of polymer electrolyte membranes for fuel cells.

Polymer membranes for high temperature proton exchange membrane fuel cell : recent advances and challenges

Unperturbed dimensions of stereoregular polymers.- Reinforcement of rubber by carbon black.- Transformations of phenolic antioxidants and the role of their products in the long-term properties of polyolefins.

Properties of polymers

The sulfonation selectivity of seven poly(ether ether ketone)s (PEEKs) was investigated, and several possessed targeted single- or double-substituted sites per repeated unit on pendant phenyl groups via the postsulfonation approach. The presence of the various pendant groups enabled postsulfonation to occur under mild reaction conditions, in much shorter times than required for the sulfonation of commercial PEEK. A series of poly(ether ketone)s (PEKs) with ion exchange capacity of 2.23−0.84 mequiv/g could be realized by controlling the length of unsulfonated segments of both homopolymers and copolymers. These side-group sulfonation polymers had excellent mechanical properties, good thermal and oxidative stability, and good dimensional stability in hot water. The methanol permeability values of Me-SPEEKK, Me-SPEEKDK, Ph-SPEEKK, and Ph-SPEEKDK at room temperature were in the range 3.31 × 10-7−9.55 × 10-8 cm2/s, which is several times lower than that of Nafion 117. Me-SPEEKK and Ph-SPEEKK also exhibited high...

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Aromatic Poly(ether ketone)s with Pendant Sulfonic Acid Phenyl Groups Prepared by a Mild Sulfonation Method for Proton Exchange Membranes

Phosphoric acid-doped polybenzimidazole (PA-PBI) used in high-temperature proton exchange membranes (HT-PEMs) frequently suffers from a serious loss of mechanical strength because of the “plasticiz...

Highly Conductive and Mechanically Stable Imidazole-Rich Cross-Linked Networks for High-Temperature Proton Exchange Membrane Fuel Cells

Soluble aromatic poly(ether ketone)s with a pendant 3,5-ditrifluoromethylphenyl group

New bisphenol monomers, (3-methyl)phenylhydroquinone and (3-trifluoromethyl)phenylhydroquinone, were prepared in a two-step synthesis. A series of poly(aryl ether ketone)s were derived from these bisphenols via a nucleophilic aromatic substitution polycondensation with various bisfluoro compounds. The polycondensation proceeded quantitatively in tetramethylene sulfone in the presence of anhydrous potassium carbonate and afforded the polymers with inherent viscosities of 0.63–0.91 dL/g. The fluorinated polymers showed lower glass-transition temperatures and higher thermal-decomposition temperatures than the corresponding nonfluorinated polymers. The solubility of the polymers was improved by the introduction of bulky pendant groups. All the polymers formed transparent, strong, and flexible films, with tensile strengths of 86.4–102.0 MPa, Young's moduli of 2.28–3.03 GPa, and elongations at break of 14–42%. All the polymers had low dielectric constants of 2.70–2.83 at 1 MHz. Compared with the methylated polymers, the trifluoromethylated polymers exhibited lower water sorption, which was attributed to the stronger hydrophobicity of the fluorine-containing groups. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3392–3398, 2002

Poly(aryl ether ketone)s with (3‐methyl)phenyl and (3‐trifluoromethyl)phenyl side groups

The practical applications of phosphoric acid-doped polybenzimidazole (PA-PBI) as high-temperature proton exchange membranes (HT-PEMs) are mainly limited by their poor dimensional-mechanical stability at high acid doping levels (ADLs) and the leaching of PA from membranes during fuel cell operation. In this work, to overcome these issues, we fabricated novel cross-linked PBI networks with additional imidazole groups by employing a newly synthesized bibenzimidazole-containing dichloro compound as cross-linker and an arylether-type Ph-PBI as matrix. Ph-PBI featured by good solubility under high molecular weight offers satisfactory film-forming ability and mechanical strength using for the matrix. Importantly, the additional imidazole moieties in BIM-2Cl endow the cross-linked PBI membranes improved dimensional-mechanical stability with simultaneously enhanced ADLs and proton conductivity. Furthermore, superior acid retention capability is obtained by incorporating porous polyhydroxy SiO2 nanoparticles into these cross-linked networks. As a result, the SiO2/cross-linked PBI composite membranes are suitable to manufacture membrane electrode assemblies (MEAs), and an excellent H2/O2 cell performance with a peak power density of 497 mW cm-2 at 160 °C under anhydrous conditions can be achieved.

Construction of High-Performance, High-Temperature Proton Exchange Membranes through Incorporating SiO2 Nanoparticles into Novel Cross-linked Polybenzimidazole Networks.

Baijun Liu

Papers

Aromatic Poly(ether ketone)s with Pendant Sulfonic Acid Phenyl Groups Prepared by a Mild Sulfonation Method for Proton Exchange Membranes

Highly Conductive and Mechanically Stable Imidazole-Rich Cross-Linked Networks for High-Temperature Proton Exchange Membrane Fuel Cells

Soluble aromatic poly(ether ketone)s with a pendant 3,5-ditrifluoromethylphenyl group

Poly(aryl ether ketone)s with (3‐methyl)phenyl and (3‐trifluoromethyl)phenyl side groups

Construction of High-Performance, High-Temperature Proton Exchange Membranes through Incorporating SiO2 Nanoparticles into Novel Cross-linked Polybenzimidazole Networks.