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Two distinct types of host polymers, [EDTA]3[PEG400]7 and [EDTA][PEG400]2, consisting of polyethereal chains linked together by EDTA chelating units, were synthesized from ethylenediaminetetraacetic acid (EDTA) derivatives and PEG400. Their structures were revealed by analytical data, viscosimetric measurements and FTIR studies. Direct dissolution of δ-LiCl and δ-MgCl2 in these prepared host polymers resulted in the following electrolytic complexes: [EDTA]3[PEG400]7/(LiCl)6.39, [EDTA]3[PEG400]7/(MgCl2)8.23, [EDTA]3[PEG400]7/(LiCl)6.39(MgCl2)6.16, [EDTA][PEG400]2/(LiCl)2.26, [EDTA][PEG400]2/(MgCl2)1.98 and [EDTA][PEG400]2/(LiCl)2.26(MgCl2)1.98.Mid- and far-FTIR spectroscopic studies revealed the following properties for all the electrolytic complexes: (a) the polyethereal chains are in the TGT conformation; (b) the Mg2+ ion could be hexa- or heptacoordinated in chelating sites of EDTA; (c) the Li+ ion is preferentially coordinated by the oxygen atoms of the residual acetate groups and polyethereal moieties.Results of conductivity measurements performed at room temperature indicated that the proposed Mg polymer electrolytes (PE) might be very useful for the development of electrochemical transducers for measuring water hardness. [Copyright &y& Elsevier]

In this paper, eight solvent-free polymer electrolytes PEG400/(MgCl2)x (0.00329≤x≤0.7000) were prepared in order to investigate the mechanism of ionic motion and the interactions existing in these systems. The study was carried out by impedance spectroscopy in the 20-Hz to 1-MHz range at different temperatures. Real and imaginary components of conductivity spectra in terms of equivalent circuit analysis (EC) and correlated ionic motion analysis based on a generalized universal power law (UPL) were investigated. Results revealed that in the PEG400/(MgCl2)x, the ionic species formed in the bulk materials are crucial for the overall conductivity. Indeed, in PEG400/(MgCl2)x, conductivity is ionic and takes place through hopping of the cationic species Mg2+ and [MgCl]+ between the coordination sites present along the polyethereal chains. [Copyright &y& Elsevier]

Membranes of polyamine (PA-SiNH 2 ) m , containing silica reacted with 3-aminopropyltriethoxysilane (APTES) in hydrolytic conditions were prepared via solution casting, followed by methylation and ion exchange process. The influence of amino-functionalized silica (Si-NH 2 ) on the properties of the obtained membrane was investigated. Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance spectroscopy (NMR) were used to investigate the chemical features of the silica and its interaction with the polyamine polymer. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the modified membrane confirmed it is stable up to 300 °C. The thermal stability is the result of the interaction of modified silica particles and polyamine polymer. It was demonstrated that the performance of the (PA-SiNH 2 ) m anion exchange membrane is greatly improved by incorporation of silica nanoparticles as compared with the anion exchange membrane (PK-PDAPm), which doesn't contain silica. Therefore, the (PA-SiNH 2 ) m is a suitable candidate for electrochemical applications. [ABSTRACT FROM AUTHOR]

The electrical response of zirconia composite polybenzimidazole membranes [PBI4N(ZrO 2 ) x ](H 3 PO 4 ) y is studied by Broadband Electrical Spectroscopy (BES), and correlated with our previous Dynamic Mechanical Analysis (DMA) and Modulated Differential Scanning Calorimetry (MDSC) measurements. The presence of nanofiller in the PBI4N polymer matrix is shown to plasticize the membrane, with a maximum effect observed at a nanofiller loading level of x ≈ 0.13. The disrupting effect of the nanofiller on the interchain dipole interactions modulates the overall electrical response of the materials. Following acid doping, a marked increase in conductivity is observed as new chemistry is installed at the interfaces between polymer and nanofiller that facilitates dipolar fluctuations and segmental motions of the polymer chains. In these composite membranes, two mechanisms of conductivity are postulated based on BES analysis; i) proton hopping between binding sites, and ii) proton hopping at the interfaces between H n PBI4N n+ /H n PBI4N n+ and H n PBI4N n+ /H m ZrO 2 m+ . The results here presented demonstrate the effect of zirconia nanofiller and subsequent acid doping on the conductivity properties of composite PBI4N membranes. Of note, at 100 °C for [PBI4N(ZrO 2 ) 0.132 ](H 3 PO 4 ) 11 , conductivity as high as 0.035 S/cm is achieved. [ABSTRACT FROM AUTHOR]

In this study, a new family of poly(vinyl alcohol)-based solid membrane electrolytes is proposed. The single ion conducting polyelectrolytes are obtained by direct lithiation of partially hydrolyzed poly(vinyl alcohol), forming a lithium-poly(vinyl alkoxide) macromolecular salt. Furthermore, in order to improve the ionic conductivity, the obtained polymer is plasticized with 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMImTFSI) ionic liquid. Thermogravimetric analysis demonstrates a thermal stability higher than 215 °C. Differential Scanning Calorimetry studies show a polymer associated glass transition event and a melting transition related to the ionic liquid domains at ca. +80 and −40 °C respectively. Fourier-transform infrared spectroscopy proves that: a) lithiation of the membrane results in an increase to the amorphic character of the polymer backbone; and b) after ionic liquid addition to the lithiated membrane, the effective coordination of lithium cations by the TFSI - anions of the ionic liquid augments the ionic conductivity of the proposed materials. Broadband electrical spectroscopy (BES) investigations reveal that this system is characterized by several polarization phenomena and dielectric relaxation events. Analysis of the BES results, using suitable models, allows for the conductivity mechanism in the proposed polymer electrolytes to be hypothesized. Finally, the ionic conductivity values of 1.29 · 10 −5  S cm −1 and 1.92 · 10 −3  S cm −1 at 30 and 80 °C render these materials very promising for application in electrochemical devices. [ABSTRACT FROM AUTHOR]

Nafion‑tungsten oxide hybrid membranes, [Nafion/(WO 3 ) x ], with varying loading levels of WO 3 nanofiller (x = 0, 0.024, 0.329) are prepared and investigated as candidates for application as solid electrolytes in vanadium redox flow batteries (VRFBs). The thermal properties of [Nafion/(WO 3 ) x ] hybrid membranes are probed both by high-resolution thermogravimetric analysis (HR-TGA) and by modulated differential scanning calorimetry (MDSC). Vibrational spectroscopy studies are carried out by: (i) Attenuated Total Reflectance - Fourier Transform Infrared spectroscopy (ATR-FTIR); and (ii) Raman spectroscopy, to elucidate the secondary structure of [Nafion/(WO 3 ) x ] and study the interactions taking place between the nanofiller and the Nafion matrix. The electrical response of [Nafion/(WO 3 ) x ] is determined by Broadband Electrical Spectroscopy (BES) and the permeability towards VO 2+ is measured by UV-VIS spectrometry. It is demonstrated that the [Nafion/(WO 3 ) x ] hybrid membranes exhibit a high ion selectivity (up to 10.6∙10 3  S∙min∙cm −3 for [Nafion/(WO 3 ) 0.329 ]) that is much improved in comparison with that characterizing recast Nafion (6.5∙10 3  S∙min∙cm −3 ). A structural model and a conductivity mechanism for the [Nafion/(WO 3 ) x ] hybrid membranes are proposed, in order to rationalize the experimental results and correlate the electrical response with the transport properties. [ABSTRACT FROM AUTHOR]

Abstract: FT-IR ATR spectroscopy has been undertaken to elucidate how the structure of Nafion™ membranes is affected by the cationic form (i.e., H+, D+, and Na+) and water content. Three distinct hydration levels were considered: (a) completely dry (λ≡Η2Ο/–SO3 − ≅0); (b) minimal hydration (λ≅2); and (c) fully hydrated (λ≅22). The measured spectra reveal that the associated cation and degree of hydration have a significant effect on the vibrational modes of the perfluoroether side chains of the ionomer. Two peaks ascribed to the SO3X terminal groups and the features attributed to the COC linkages were clearly identified. The latter were studied in detail, and are shown to be diagnostic of the conformation of the side chains. A comprehensive framework of interpretation of the experimental results is proposed, with emphasis on: (a) the role played by the interactions between the SO3X terminal groups of the different side chains; and (b) how the latter interactions are affected by the amount of H2O or D2O in the samples. In particular, reference is made to the formation and spatial distribution of the positively-charged species characterized by significantly different structural features. [Copyright &y& Elsevier]

An alternated copolymer with the formula α-hydro-ω-oligo(oxyethylene)hydroxy-poly[oligo(oxyethylene)oxydimethylsililene] and a molecular weight of 9860 was synthesized. Doping of this polymer with the anhydrous salt δ-MgCl2 resulted in a new magnesium electrolytic complex poly[PEG400-alt-DEOS]/(MgCl2)0.26.The structural hypothesis for the polymer was proposed on the basis of elemental analyses and molecular weight. Detailed 1H-, 13C-, and 29Si-NMR spectral investigations fully confirmed the structure of poly[PEG400-alt-DEOS]. Mid-infrared region (MIR) FT-IR studies of the polymer showed that it presents (1) a sufficient number of terminal hydroxyl groups to confer a substantial degree of dissolution and salt-dissociation in the polymer complex; and (2) polyethereal fragments in a conformational geometry close to TGT (T=trans, G=gauche). The conductivity against temperature plot for this very amorphous magnesium polymer electrolyte demonstrated that the material conducts ionically by means of two types of charge migration mechanisms. [Copyright &y& Elsevier]