Poly(2,6-dimethyl-1,4-phenylene oxide) containing imidazolium-terminated long side chains as hydroxide exchange membranes with improved conductivity

Composite Anion-Exchange Membrane Fabricated by UV Cross-Linking Vinyl Imidazolium Poly(Phenylene Oxide) with Polyacrylamides and Their Testing for Use in Redox Flow Batteries

Composite anion-exchange membranes (AEMs) consisting of a porous substrate and a vinyl imidazolium poly(phenylene oxide) (VIMPPO)/acrylamide copolymer layer were fabricated in a straightforward process, for use in redox flow batteries. The porous substrate was coated with a mixture of VIMPPO and acrylamide monomers, then subsequently exposed to UV irradiation, in order to obtain a radically cured ion-exchange coating. Combining VIMPPO with low-value reagents allowed to significantly reduce the amount of synthesized ionomer used to fabricate the mem- brane down to 15%. Varying the VIMPPO content also allowed tuning the ionic transport properties of the resulting AEM. A series of membranes with different VIMPPO/acrylamides ratios were prepared to assess the optimal composition by studying the changes of membranes properties-water uptake, area resistivity, permeability, and chemical stability. Characterization of the membranes was followed by cycling experiments in a vanadium RFB (VRFB) cell. Among three composite membranes, the one with VIMPPO 15% w/w-reached the highest energy efficiency (75.1%) matching the performance of commercial ion-exchange membranes (IEMs) used in VRFBs (Nafion® N 115: 75.0% and Fumasep® FAP 450: 73.0%). These results showed that the proposed composite AEM, fabricated in an industrially oriented process, could be considered to be a lower-cost alternative to the benchmarked IEMs.

Highly conductive and robust composite anion exchange membranes by incorporating quaternized MIL-101(Cr)

With well-defined channels and tunable functionality, metal-organic frameworks (MOFs) have inspired the design of a new class of ion-conductive compounds. In contrast to the extensive studies on proton-conductive MOFs and related membranes attractive for fuel cells, rare reports focus on MOFs in preparation of anion exchange membranes. In this study, chloromethylated MIL-101(Cr) was prepared and incorporated into chloromethylated poly (ether ether ketone) (PEEK) as a multifunctional filler to prepare imidazolium PEEK/imidazolium MIL-101(Cr) (ImPEEK/ImMIL-101(Cr)) anion exchange membrane after synchronous quaternization. The successful synthesis and chloromethylation of MIL-101(Cr) were verified by transmission electron microscopy, X-ray diffraction and Fourier transform infrared spectroscopy while the enhanced performance of composite membranes in hydroxide conductivity, mechanical strength and dimensional stability were evaluated by alternating-current impedance, electronic stretching machine and measurement of swelling ratio. Specifically, incorporating 5.0wt% ImMIL-101(Cr) afforded a 71.4% increase in hydroxide conductivity at 20°C, 100% RH. Besides, the composite membranes exhibited enhanced dimensional stability and mechanical strength due to the rigid framework of ImMIL-101(Cr). At room temperature and the ImMIL-101(Cr) content of 10wt%, the swelling ratio of the ImPEEK/ImMIL-101(Cr) was 70.04% lower while the tensile strength was 47.5% higher than that of the pure membrane.

Fabrication of N1-butyl substituted 4,5-dimethyl-imidazole based crosslinked anion exchange membranes for fuel cells

Novel N1, C4, C5-substituted imidazolium-based crosslinked anion exchange membranes (AEMs) are prepared by the incorporation of polybenzimidazole (PBI) into the poly(vinylbenzyl chloride) (PVBC) matrix.

Facile construction of crosslinked anion exchange membranes based on fluorenyl-containing polysulfone via click chemistry

Crosslinked fluorenyl-containing polysulfone based anion exchange membranes have been successfully synthesized via click chemistry with improved properties by controlling the crosslinking degree and micro-phase structure.

Imidazolium-functionalized anion exchange membranes using poly(ether sulfone)s as macrocrosslinkers for fuel cells

The incompatibility of the hydrophilic imidazolium cations from the functionalized poly(vinyl imidazole) with the long hydrophobic poly(ether sulfone) chain promoted the phase separation. The PES/PVIIL-0.4 membrane displayed good single cell performance.

Synthesis of novel copolymers based on p-methylstyrene, N,N-butylvinylimidazolium and polybenzimidazole as highly conductive anion exchange membranes for fuel cell application

A series of copolymers based N,N-butylvinylimidazolium, p-methylstyrene and polybenzimidazole as anion exchange membrane materials VIBx/PMSy/PBIz.