International audience1,2,3-Triazolium-based poly(ionic liquid)s containing a triethylene glycol spacer were synthesized from the polyaddition of an alpha-azide-omega-alkyne monomer by copper-catalyzed azide-allcyne cycloaddition (CuAAC) followed by quaternization reactions with alkyl halides and subsequent anion exchanges with different fluorinated salts. A detailed structure-property relationship for solubility, thermal stability, and ionic conductivity was investigated by means of H-1 NMR spectroscopy, differential scanning calorimetry (DSC), thermogravinietric analysis (TGA), and broadband dielectric spectroscopy (BDS). One of these poly(ionic liquid)s with a methyl substituent and bis(trifluoromethylsulfonyl)imide anion exhibits an ionic conductivity of 2 x 10(-5) S cm(-1) at 30 degrees C, which is on par with the best PILs with side-chain charge carriers reported so far and is much higher than any previously reported ionenes. The straightforward synthesis along with the broad structural design and enhanced properties of this new class of poly(ionic liquid)s offer both fundamental and applicative perspectives

The impact of triethylammmonium trifluorosulfonate (TFTEA) concentration on the nanostructuration and electrochemical, thermo mechanical, transport properties of doped Nafion membranes has been studied. The Nafion membranes neutralized with triethylamine (Nafion–TEA) have been doped with various amounts of TFTEA using the swelling method. The effect of the TEA neutralization was first studied. The results suggest a specific arrangement of TEA cations and a quite low water uptake. Concerning TFTEA doped membranes, the evolution trend of nanostructure of TFTEA doped Nafion is very similar to that of acidic Nafion swollen by water, with a slope equal to 1.33. However, at high TFTEA concentration (29 wt %) in this composite membrane, the average hydrophobic–hydrophilic phase separation distance appears to be 59 Å while it is 41 Å in hydrated acidic Nafion at the same volume fraction of polymer, which could be related to a much more heterogeneous distribution of TFTEA in Nafion–TEA than water molecules in acidic Nafion. Increasing TFTEA concentration in Nafion–TEA membranes results in significant increase of anhydrous ionic conductivity but no significant change in gas-permeability coefficients (hydrogen, oxygen). Water sorption experiments at 25 °C show that water uptake increases with increasing water activity and percentage of TFTEA in the membrane. However, the water sorption capacity of the TFTEA molecules within the membrane is limited due to the hindering effect of the polymer matrix.

International audienceLarge-scale commercialisation of Proton Exchange Membrane Fuel Cell (PEMFC) technology for automotive and stationary applications demands the development of a robust, durable and cost-effective materials. In this regard, ionomer membranes being present at the core of PEMFCs are required to maintain elevated proton conductivity, high mechanical strength and low gas permeability during the lifespan of the fuel cell. These challenges are addressed by investigating novel nano-structured membrane materials possessing long-range spatial organisation of ionic and hydrophobic domains at the micro-and nano-scales. Electrospinning, a versatile and easily up-scalable tool for the preparation of nanofibrous polymers and ceramics with targeted architectures, is being extensively applied for the development of nanostructured electrolyte membranes. This review describes the most important advances in the use of electrospun materials for the preparation of new generation fuel cell proton conducting membranes. It also highlights the challenges to be overcome and the new directions and future application fields of composite nanofibre-based membranes in the broader context of energy materials

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International audienceA series of cationic poly(acrylate ionic liquid)s having a triethylene glycol (TEG) spacer and a pendant 1,2,3-triazolium group is synthesized by post-polymerization sequential chemical modifications. A chloride-functionalized polyacrylate common precursor is first obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization of a TEG-based chloride-functionalized acrylate. Sequential azidation, copper-catalyzed azide-alkyne cycloaddition with 1-pentyne and alkylation of the resulting 1,2,3-triazole by methyl iodide affords a poly(acrylate ionic liquid) having pendant 3-methyl-4-propyl-1,2,3-triazolium iodide groups. Further anion metathesis with three different fluorinated salts yields a series of 1,2,3-triazolium-based PILs with distinct counter anions. The polymer precursors and resulting poly(1,2,3-triazolium ionic liquid) s (PTILs) are characterized by H-1 NMR spectroscopy, size exclusion chromatography (SEC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and broadband dielectric spectroscopy (BDS). Well-defined PTIL derivative with bis(trifluoromethane) sulfonimide anion (M-n = 113,600 g mol(-1) and D = 1.23) exhibits the lowest glass transition temperature (T-g = -36 degrees C), the highest thermal stability (T-d10 = 321 degrees C) and the highest anhydrous ionic conductivity (sigma(DC) = 1.1 x 10(-5) S cm(-1) at 30 degrees C) of the series

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Trifluoromethanesulfonate of triethylammmonium (TFTEA) doped Nafion-TEA membranes have been evaluated to understand the impact of different elaboration methods, i.e., swelling and casting, on their nanoscale morphology using SANS and resulting functional properties such as electrochemical, thermomechanical, and transport properties. The effect of transformation of acidic side chains of Nafion into ammonium side chains (Nafion-TEA) was first compared for the Nafion-TEA membrane elaborated by casting with the one elaborated by modification of extruded commercial Nafion117 membrane. Concerning TFTEA doped membranes, their nanostructuration is very similar whatever the processing mode despite some key differences. The casting based membranes exhibit higher and/or more heterogeneous swelling of ionic domains of Nafion-TEA by TFTEA and lower impact of TFTEA on the long-range crystalline order in Nafion-TEA. Casting based membranes present better thermomechanical properties compared to swelling based membranes above 150 °C and sustain a storage modulus of 1 MPa in the temperature range of 150−180 °C. With increasing TFTEA content as well as temperature, both types of membranes show an increase in the ionic conductivity of a similar order but no significant changes in hydrogen and oxygen-permeability coefficients. Both kinds of doped membranes exhibit similar sorption behavior (e.g., an increase in water uptake with increasing TFTEA content), though the results from GAB modeling suggest that morphology developed by casting is more favorable for the sorption of water molecules in middle range activity. Current density of 0.85 A/cm 2 at 0.6 V was obtained with a membrane containing 20% TFTEA.

Microwave heating holds all the aces regarding development of effective and environmentally friendly methods to perform chemical transformations. Coupling the benefits of microwave-enhanced chemistry with highly reliable copper-catalyzed azide-alkyne cycloaddition (CuAAC) click chemistry paves the way for a rapid and efficient synthesis procedure to afford high performance thermoplastic materials. We describe herein fast and high yielding synthesis of 1,2,3-triazole-functionalized polysulfone through microwave-assisted CuAAC as well as explore their potential as phosphoric acid doped polymer electrolyte membranes (PEM) for high temperature PEM fuel cells. Polymers with various degrees of substitution of the side-chain functionality of 1,4-substituted 1,2,3-triazole with alkyl and aryl pendant structures are prepared by sequential chloromethylation, azidation, and microwave-assisted CuAAC using a range of alkynes (1-pentyne, 1-nonyne, and phenylacetylene). The completeness of reaction at each step and the purity of the clicked polymers were confirmed by (1)H-(13)C NMR, DOSY-NMR and FTIR-ATR spectroscopies. The thermal and thermochemical properties of the modified polymers were characterized by differential scanning calorimetry and thermogravimetric analysis coupled with mass spectroscopy (TG-MS), respectively. TG-MS analysis demonstrated that the commencement of the thermal degradation takes place with the decomposition of the triazole ring while its substituents have critical influence on the initiation temperature. Polysulfone functionalized with 4-phenyl-1,2,3-triazole demonstrates significantly higher Tg, Td, and elastic modulus than the ones bearing 4-propyl-1,2,3-triazole and 4-heptyl-1,2,3-triazole groups. After doping with phosphoric acid, the functionalized polymers with acid doping level of 5 show promising performance with high proton conductivity in anhydrous conditions (in the range of 27-35 mS/cm) and satisfactorily high elastic modulus (in the range of 332-349 MPa).