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Anion exchange membranes (AEMs) are key core materials in water electrolysis, requiring both high conductivity and good dimensional stability and chemical durability. In this work, a series of poly(biphenyl piperidinium) AEMs with side octadecyl groups (Q18PBP-x) are prepared through the superacid catalyzed polymerization and grafting reactions. The long hydrophobic alkyl side chains attached onto the ether-free backbone effectively improve the dimensional stability, chemical durability and ionic conductivity of the obtained AEMs at high temperature. At 80 °C, the water absorption and swelling rate of Q18PBP-30 membrane with IEC of 2.28 mmol g−1 are 47.8 and 10.8%, respectively. Its ionic conductivity is 79.4 mS cm−1 and only decrease by 6.9% after 480 h of immersion in 2 M NaOH at 80 °C. The current density of water electrolyzer assembled with representative Q18PBP-30 membrane reaches 0.53 A cm−2 in 2 M KOH at 2.1 V, and its voltage fluctuation of durability testing is only 15.8% after 480 h at the current density of 300 mA cm−2. These results suggest that grafting long hydrophobic alkyl chains on the backbone of AEMs is a promising strategy to enhance their properties for water electrolysis. [ABSTRACT FROM AUTHOR]

Composite membranes based on Nafion (N115) loaded with furfuryl alcohol (FA) were prepared byin situacid-catalyzed polymerization technique, with the aim to improve the ionic conductivity of Nafion membranes. The functionalization, thermal stability, electrical properties and mechanical strength of N115-PFA composites was analyzed by means of Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), thermogravimetric analysis (TGA), electrical impedance spectroscopy, dynamic vapor sorption (DVS) and dynamic mechanical analyser (DMA). The FA loading in the resultant composites had a positive correlation with the water uptake (Wu), water vapor uptake (Wvu), ionic conductivity and thermo-mechanical stability. At low polyfurfuryl alcohol (PFA) loading, these membranes displayed higher Wuand improved ionic and electrical properties. Further, the thermo-mechanical stability also gradually increased with the PFA loading. All the composites showed a well-defined glass transition temperature in DMA, which shifted to higher temperature with repeated PFA loading. Overall, the results indicate that the developed composite membrane are promising for low temperature polymer electrolyte membrane (PEM) fuel cells. [ABSTRACT FROM AUTHOR]

In this work, the influence of 2-mercaptobenzimidazole (2-MCBI) on poly(vinylidinefluoride-co-hexafluoropropylene)/KI/I2(PVDF-HFP/KI/I2) polymer electrolytes were studied. The pure and different weight percentage ratios (20, 30, 40 and 50%) of 2-MCBI doped PVDF-HFP/KI/I2electrolytes were prepared by a solution casting technique. The as-prepared polymer electrolyte films were characterized using various techniques such as Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), X-ray diffractometer (XRD), alternating current (AC)-impedance analysis. The addition of 2-MCBI with pure PVDF-HFP/KI/I2was found to increase the ionic conductivity of electrolyte. Among the various additions, 30 wt% 2-MCBI doped PVDF-HFP/KI/I2showed the highest room temperature ionic conductivity values than the others. The dye-sensitized solar cell (DSSC) fabricated using this optimized polymer electrolyte achieved a high power conversion efficiency of 4.40% than the pure PVDF-HFP/KI/I2(1.74%) at similar experimental conditions. Thus, the 2-MCBI doped polymer electrolyte has proven to be an effective substitute to the liquid electrolyte in DSSCs. [ABSTRACT FROM AUTHOR]

Phenol formaldehyde resins are of interest for different industrial and electronic applications. However, the toxic nature of formaldehyde and the extreme reaction conditions for the synthesis of these polymers have severely limited their use in today's markets. We present here a novel, biocatalytic approach where the enzyme horseradish peroxidase is used to polymerize phenol in the presence of a template such as polyethylene oxide. Here the template assists as a surfactant that can both emulsify the phenol and polyphenol chains during polymerization and provide water/solvent solubility of the final polyphenol/template complex. The reactants and the reaction conditions of this method are mild and result in high molecular weight, electrically and optically active, water-solvent soluble complexes of polyphenol and the template used. High molecular weight water-soluble polyphenol/polyethylene oxide complexes were formed. [ABSTRACT FROM AUTHOR]

Template assisted enzymatic polymerization of phenol has been carried out in aqueous media at room temperature. The templates used to facilitate this reaction, were polystyrene sulfonate, lignin sulfonate and dodecyl benzene sulfonate. The enzyme, horseradish peroxidase, proved to be an active catalyst for the polymerization, yielding a phenolic polymer that is permanently complexed with the template used. These polyphenol complexes are high molecular weight, soluble in water and/or mixed organic solvents and show good thermal stability. Under certain conditions, physical SPS-polyphenol gels can be formed in water that have high ionic conductivity. UV-vis, FTIR and electro-absorption spectroscopy show the presence of significant backbone conjugation and NLO properties. This novel enzymatic approach is a simple, inexpensive and environmentally friendly way to prepare processable polyphenolic materials with interesting electrical and optical properties. †Deceased. [ABSTRACT FROM AUTHOR]

The synthesis of a new class of polyphenylenes substituted with a large number of phenyl and benzo-crown-ether groups has been described. The polymers, prepared by Suzuki cross-coupling reaction between polyphenylated dibromide and benzene-1,4-diboronic acid, exhibit outstanding solubility in common organic solvents such as THF and chloroform. Preliminary results on molecular weights and thermal analysis of one representative polymer are discussed. [ABSTRACT FROM AUTHOR]

Solid state ionics has a key role to play in the field of modern electronics. Solid electrolytes would not only make batteries leak proof, but also space efficient, and having high power densities. In the present investigation, attempts were made to synthesize a new solid polymer electrolyte and characterize its electrical properties. An interpenetrating polymer network (IPN) of polyethylene oxide-polyurethane/poly(4-vinylpyridine) (PEO-PU/PVP), was synthesized as host polymer and subsequently doped with LiClO4. The IPN structure improves the mechanical properties. DSC studies showed an inward shift of glass transition temperature (Tg) in the range -50°C to -35°C. Conductivity measurements showed σ values in the range of 10-8Scm-1. The maximum conductivity (σ) of the system (∼5 × 10-8 Scm-1) was observed at EO/Li ratio in the range of 10–15. Impedance analysis showed interfacial polarization within the polymer matrix. †IICT communication number 4490. [ABSTRACT FROM AUTHOR]

Poly[lithium-N(4-sulfophenyl) maleimide -co- methoxy oligo-(oxyethylene) methacrylates] [P(LiSMOEn)s] with three different oligoether side chains and different salt concentrations were synthesized. The copolyelectrolytes are essentially random in structure, with blocks of methoxy oligo(oxyethylene) meth-acrylate (MOEnM) recurring sporadically in between the salt units of N(4-sulfophenyl) maleimide. They all show two glass transitions in the temperature range of -100 to 100°C. The first one below -30°C is assigned to the oligo(oxyethylene) side chain (Tg1), while the second one located between 20 and 50°C is attributed to the main chain of the polymer host (Tg2). The maximum ionic conductivity of the copolymer electrolytes, 1.6 × 10-7 S cm-1 at 25°C, occurs at lithium salt concentration [Li+]/[EO] = 2.2 mol%. The ionic conductive behavior of the copolyelectrolytes follows the Vogel-Tammann-Fulcher (VTF) equation. Moreover, a special VTF behavior exists in the copolymers with shorter oligoether side chain and higher salt concentration. Sweep voltammetric results indicate that these copolyelectrolytes have a good electrochemical stability window. [ABSTRACT FROM AUTHOR]