We have prepared a hybrid inorganic/organic, anhydrous proton-conducting polymer electrolyte (MePEG(3)SiO(3))(n). Structural characterization of this MePEG(3) polymer through Si-29 NMR spectroscopy and gel-permeation chromatography indicates that our MePEG(3) polymer is composed of several different structures giving a distribution of molecular weights and silicon resonances. In this article, we show that the sol-gel-prepared MePEG(3) polymer is primarily composed of incompletely condensed T-8 silsesquioxane clusters. These incompletely condensed T-8 clusters are seen in the Si-29 NMR spectra at chemical shifts between -62 and -70 ppm. The minority composition of the MePEG(3) polymer contains a small amount of completely condensed T-6 silsesquioxane clusters, observed at -55.5 ppm, and T, dimers from -48 to -50 ppm. End-group analysis shows the presence of 0.67 uncondensed Si-OH groups per silicon atom in the MePEG(3) polymer, supporting the presence of incompletely condensed or ladder-type structures. The completely condensed POSS cluster (MePEG(3))(8)T-8 was synthesized for study as a model compound, showing Si-29 NMR peaks between -65.5 and -69 ppm. "Q"-type silicon species are observed in the Si-29 NMR spectra of the MePEG(3) monomer and MePEG(3) polymer at approximately -80 to -90 and -101 ppm, respectively. The Q-type structures are generated from a coupling of triethoxysilane formed in the hydrosilation reaction.

Proton conducting electrolytes composed of mixtures of a MePEGnSO3H acid and a sol−gel based MePEGn polymer have been prepared. These solutions display anhydrous proton conductivity reaching a maximum value of 1.38 × 10-5 S/cm at 55 °C with a 1.32 M mixture of MePEG16SO3H dissolved in the MePEG12 polymer. The molar equivalent conductivity of the MePEGnSO3H acid is correlated with the volume fraction of PEG present in the mixture. This result indicates that conductivity in these solutions of acid and polymer is a function of the PEG content strongly suggesting the presence of a Grotthus mechanism of conductivity. In addition, we show the lack of a dependence of ionic and equivalent conductivity on the size of the MePEGnSO3H acid, indicating little to no contribution to conductivity from the vehicle mechanism.

Proton conducting electrolyte gels composed of short polyether “tails” bound to a sol–gel matrix ([MePEG350S(CH2)3SiO3]n) and sulfonated oligomeric methyl polyethylene glycol (MePEG350-SO3H) exhibit dry and unplasticized H+ conductivities of up to 2.3×10−5S/cm at 50°C under vacuum. Proton conductivities in these electrolyte gels increase with added acid (MePEG350-SO3H). Activation barriers to H+ conductivity were between 20kJ/mol for 0.25M MePEG350-SO3H in (MePEG350S(CH2)3SiO3)n, and 38kJ/mol for the 1.26M mixture. Air equilibrated conductivities in these materials reached a maximum of 3.4×10−4S/cm for neat MePEG350-SO3H.

We have synthesized highly viscous, room-temperature, molten salts by associating various Ru(NH3)(5)L cations (L = 4,4'-bipyridine, pyrazine, pyridine, 3-chloropyridine, benzonitrile) with polyether-tailed sulfonate anions. Microelectrode voltammetry in the undiluted melts yields, on the basis of charge transport occurring by electron hopping, electron self-exchange rate constants (k(EX)) for the various Ru3+/2+ couples. The rate constant (and activation barrier) for the pyrazine bridged binuclear pentaamineruthenium melt (Creutz-Taube ion) is similar to those obtained for mononuclear pentaammine[ligand]ruthenium melts, meaning that charge transport in the former is dominated by the rate of intermolecular, not intramolecular, electron transfer. The data at 35 degreesC are (Creutz-Taube ion) k(EX) = 3.7 x 10(4) M-1 s(-1), (pyridine) 1.1 x 10(4) M-1 s(-1), (3-chloropyridine) 2 x 10(4) M-1 s(-1), and (benzonitrile) 3 x 10(4) M-1 s(-1). All k(EX) values are smaller than those for [Ru2+/3+(bpy)(3)] in semisolid melts having equivalent MePEG tail contents.

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTIntermolecular Optical Electron Transfers in Polyether Hybrid Molten Salts of Mixed-Valent Ruthenium ComplexesJason E. Ritchie and Royce W. MurrayView Author Information Kenan Laboratories of Chemistry University of North Carolina Chapel Hill, North Carolina 27599 Cite this: J. Am. Chem. Soc. 2000, 122, 12, 2964–2965Publication Date (Web):March 10, 2000Publication History Received2 December 1999Published online10 March 2000Published inissue 1 March 2000https://pubs.acs.org/doi/10.1021/ja994221khttps://doi.org/10.1021/ja994221krapid-communicationACS PublicationsCopyright © 2000 American Chemical SocietyRequest reuse permissionsArticle Views204Altmetric-Citations24LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose SUBJECTS:Charge transfer,Counterions,Energy,Ions,Redox reactions Get e-Alerts

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Methods capable of forming highly organized monolayers on top of YBa2Cu3O7 (YBCO), a high T-c superconductor, have been identified and are described for the first time. Here, grazing reflectance infrared fourier transform spectroscopy (GRIFTS) is employed to evaluate the degree of order for these monolayer structures. Through these investigations, it is found that while octadecylamine forms a well-ordered, crystalline like monolayer on the surface of c-axis-oriented YBa2Cu3O7 thin films. the same reagent adsorbed onto polycrystalline YBa2Cu3O7 pellets affords disordered, liquid-like monolayers. Computational studies of alkylamine packing, using a molecular mechanics methodology reveal two plausible structures for the crystalline-like monolayer. A GRIFTS comparison of primary, secondary, and tertiary alkylamine reagents also has been completed, and the substitution pattern dependence of the monolayer order has been assessed experimentally. Moreover, comparisons between amine monolayers on top of YBa2Cu3O7 and alkyl thiol reagents on gold surfaces are made using GRIFTS and thermal desorption experiments. This work documents the initial report of the assembly and characterization of organized monolayers supported on high-T-c superconductor surfaces, the most complex substrate yet reported capable of fostering ordered adsorbate layers.

The surface coordination chemistry of the cuprate superconductor, YBa2Cu3O7-delta has been extensively surveyed using cyclic voltammetry in conjunction with a series of redox-active ferrocenyl containing adsorbate molecules. Evidence supporting the adsorption of molecules with primary alkylamine, secondary alkylamine, tertiary alkylamine, arylamine, thiol, disulfide, and selenol functionalities is reported. Cyclic voltammetry, atomic force microscopy, scanning electron microscopy, X-ray powder diffraction and resistivity vs temperature measurements were utilized to evaluate the influence of the modification conditions on the bulk and surface properties of the high-T-c superconductor. The spontaneous adsorption of redox-active alkylamines, arylamines, and thiols onto the surfaces of cuprate materials has been shown to produce stable and robust monolayer films with no apparent damage to the bulk properties of the underlying superconduetors. Of the molecules studied thus far, primary alkylamines have been determined to be the optimum adsorbates based upon surface coverage values and monolayer durability. Tertiary alkylamines form monolayers on YBa2Cu3O7-delta with an electrochemical persistence comparable to primary alkylamine monolayers, suggesting that hydrogen binding with the surface is not necessary for adsorption. We propose that amines act as Lewis bases and bind to Lewis acidic Cu surface site(s) in YBa2Cu3O7-delta to form stable coordination bond(s).