Polymer electrolyte membranes based on p‐toluenesulfonic acid doped poly(1‐vinyl‐1,2,4‐triazole): Synthesis,thermal and proton conductivity properties

Throughout this work, the synthesis, thermal as well as proton conducting properties of acid doped heterocyclic polymer were studied under anhydrous conditions. In this context, poly(1‐vinyl‐1,2,4‐triazole), PVTri was produced by free radical polymerization of 1‐vinyl‐1,2,4‐triazole with a high yield. The structure of the homopolymer was proved by FTIR and solid state ¹³C CP‐MAS NMR spectroscopy. The polymer was doped with p‐toluenesulfonic acid at various molar ratios, x = 0.5, 1, 1.5, 2, with respect to polymer repeating unit. The proton transfer from p‐toluenesulfonic acid to the triazole rings was proved with FTIR spectroscopy. Thermogravimetry analysis showed that the samples are thermally stable up to ～250 °C. Differential scanning calorimetry results illustrated that the materials are homogeneous and the dopant strongly affects the glass transition temperature of the host polymer. Cyclic voltammetry results showed that the electrochemical stability domain extends over 3 V. The proton conductivity of these materials increased with dopant concentration and the temperature. Charge transport relaxation times were derived via complex electrical modulus formalism (M*). The temperature dependence of conductivity relaxation times showed that the proton conductivity occurs via structure diffusion. In the anhydrous state, the proton conductivity of PVTri1PTSA and PVTri2PTSA was measured as 8 × 10^?4 S/cm at 150 °C and 0.012 S/cm at 110 °C, respectively. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1016–1021, 2010     

Bridged Polysilsesquioxane Xerogels Functionalizated by Amine- and Thiol- Groups: Synthesis, Structure, Adsorption Properties

Bridged polysilsesquioxane xerogels containing amine (–NH₂; –NH(CH₂)₂NH₂; —NH) and thiol (–SH) groups were synthesized by hydrolytic polycondensation of 1,2-bis(triethoxysilyl)ethane, 1,4-bis(triethoxysilyl)benzene and appropriate trifunctionalized silanes in the presence of a fluoride-ion catalyst in an ethanol solution. ²⁹Si CP/MAS NMR give indication of the molecular framework of these materials formed by structural T¹, T² and T³ units. 3-aminopropyl or 3-mercaptopropyl groups accessible to proton or metal ions are fixed to the xerogel surface by the siloxane bonds. IR and ¹³C CP/MAS NMR data clearly show that 3-aminopropyl groups form hydrogen bonds. The same data testify that all xerogels contain non-condensed silanol groups and some fraction of non-hydrolyzed ethoxygroups. Functionalized polysilsesquioxane xerogels obtained by means of organic spacers have a porous structure (500–1000 m²/g) and a high content of functional groups (1.0–2.7 mmol/g). AFM data indicate that xerogels are formed by aggregating primary particles—the size of such aggregates is in the range 30–65 nm. It was established that the main factors influencing the structure and adsorption properties considered hybrid materials are: the nature and geometrical size of the functional groups, spacer flexibility and, in some cases, the ratio of the reacting alkoxysilanes and the ageing time of the gel.     

Investigating the two inequivalent NH2(CH3)2 ions in [NH2(CH3)2]2CuCl4 using magic angle spinning nuclear magnetic resonance

The structural change near the phase transition temperatures of [NH₂(CH₃)₂]₂CuCl₄ is discussed in terms of the chemical shifts and the spin-lattice relaxation times T_1ρ in the rotating frame for ¹H MAS NMR and ¹³C CP/MAS NMR. The ¹H T_1ρ undergoes molecular motion near the phase-transition temperature (T_C2 = 253 K). In addition, the two inequivalent [NH₂(CH₃)₂] (1) and [NH₂(CH₃)₂] (2) sites were distinguishable by the ¹³C chemical shift. And, the most significant change was observed at T_C2 for the ¹³C CP/MAS NMR spectrum; this temperature corresponds to a ferroelastic phase transition with different orientations.     

Proton conductivity survey of the acid doped copolymers based on 4‐vinylbenzylboronic acid and 4(5)‐vinylimidazole

In this work, poly(4‐vinylbenzylboronic acid‐co‐4(5)‐vinylimidazole) (poly(4‐VBBA‐co‐4‐Vim)) copolymers were synthesized by free‐radical copolymerization of the monomers 4‐VBBA and 4‐Vim at various monomer feed ratios. The copolymers were characterized by ¹H MAS NMR and ¹¹B MQ‐MAS NMR methods and the copolymer composition was determined via elemental analysis. The membrane properties of these copolymers were investigated after doping with phosphoric acid at several stoichiometric ratios. The proton exchange reaction between acid and heterocycle is confirmed by FTIR. Thermal properties of the samples were investigated via thermogravimetric analysis (TGA) and Differential scanning calorimetry (DSC). The morphology of the copolymers was characterized by x‐ray diffraction, XRD. The temperature dependence of proton conductivities of the samples was investigated by means of impedance spectroscopy. Proton conductivity of the copolymers increased with the doping ratio and reached to 0.0027 S/cm for poly(4‐VBBA‐co‐4‐Vim)/2H₃PO₄ in the anhydrous state. The boron coordination in the copolymer was determined by ¹¹B MQ‐MAS experiment and the coexistence of three and four coordinated boron sites was observed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 1267–1274, 2009     

Magic angle carbon-13 NMR study of solid poly(ethylene naphthalene-2,6-dicarboxylate)

Amorphous (1) and semicrystalline (2) samples of poly(ethylene naphthalene-2,6-dicarboxylate) (PEN) have been investigated by cross-polarization/magic angle spinning (CP/MAS) ¹³C NMR at 26°C (1 and 2), 100°C (1) and 120°C (2) in order to study the phase structure and the local motion of polymer chain segments at temperatures below and close to T_g (120°C). The lineshape of the ethylene unit ¹³C signal in sample 2 is consistent with the presence of two components which were assigned to trans and gauche conformations. The first component arises mainly from the crystalline regions and the second one from the amorphous part. Cross-polarization curves were traced by changing the contact time between carbon and proton reservoirs. T_CH (cross relaxation time) and proton T_1p (spin-lattice relaxation time in the rotating frame) values were obtained as best fit parameters by fitting calculated curves to the experimental data. All ¹³C NMR data are consistent with the presence of highly rigid ethylene units in both semicrystalline and amorphous samples within the temperature range (T) investigated. This result is in disagreement with the ¹H NMR wide line spectra which showed a noticeable narrowing of the linewidth with increasing temperature in the same range, hence indicating a great mobility of the chain segments. To account for this discrepancy a qualitative model based on the existence of two distinct dynamic regions, one where motion is highly restricted and the other one where large reorientations of ethylene group torsional angles take place, is suggested. The NMR results led to the conclusion that three structural phases are present in PEN: crystalline, very rigid amorphous, and very mobile amorphous. © 1995 John Wiley & Sons, Inc.     

Solid‐state 1H → 19F/19F → 1H CP/MAS NMR study of poly(vinylidene fluoride)

Solid‐state ¹H → ¹⁹F and ¹⁹F → ¹H cross‐polarization magic angle spinning (CP/MAS) NMR spectra have been investigated for a semicrystalline fluoropolymer, namely poly(vinylidene fluoride) (PVDF). The ¹H → ¹⁹F CP/MAS spectra can be fitted by five Lorentzian functions, and the amorphous peaks were selectively observed by the DIVAM CP pulse sequences. Solid‐state spin‐lock experiments showed significant differences in T_1ρ^F and T_1ρ^H between the crystalline and amorphous domains, and the effective time constants, T_HF* and T_1ρ*, which were estimated from the ¹H → ¹⁹F CP curves, also clarify the difference in the strengths of dipolar interactions. Heteronuclear dipolar oscillation behaviour is observed in both standard CP and ¹H → ¹⁹F inversion recovery CP (IRCP) experiments. The inverse ¹⁹F → ¹H CP‐MAS and ¹H → ¹⁹F CP‐drain MAS experiments gave complementary information to the standard ¹H → ¹⁹F CP/MAS spectra in a manner reported in our previous papers for other fluoropolymers. The value of N_F/N_H (where N is a spin density) estimated from the CP‐drain curve is within experimental error equal to unity, which is consistent with the chemical structure. Copyright © 2001 John Wiley & Sons, Ltd.     

Synthesis,characterization, and modification of poly(tert-butyl methacrylate-b-alkyl methacrylate-b-tert-butyl methacrylate) by group transfer polymerization

Different poly(tert-butyl methacrylate) (PTBMA)-poly(alkyl methacrylate) (PAMA, alkyl=CH₃, n-C₄H₉) triblock copolymers were synthesized by group transfer polymerization. They were obtained by first preparing “living” PAMA using a difunctional initiator, followed by polymerization of TBMA in THF at room temperature, in the presence of a nucleophilic catalyst. The segment molecular weights and compositions of TBMA segment could be controlled by regulating the feed ratio of two monomers and the ratio of monomer to initiator. As supported by ¹H-NMR, IR analysis, and titration, the PTBMA blocks could be quantitatively hydrolyzed into poly(methacrylic acid) (PMAA) blocks whereas the PAMA blocks were not hydrolyzed. The water-soluble amphiphiles prepared by neutralization of the PMAA block displayed surface-active behavior in water, which was characterized by a critical micelle concentration. The thermogravimetric analysis demonstrated the loss of tert-butyl groups. © 1992 John Wiley & Sons, Inc.     

Lanthanide‐Based Layer‐Type Two‐Dimensional Coordination Polymers Featuring Slow Magnetic Relaxation,Magnetocaloric Effect and Proton Conductivity

Three lanthanide‐based two‐dimensional (2D) coordination polymers (CPs), [Ln(L)(H₂O)₂]_n, {H₃L=(HO)₂P(O)CH₂CO₂H; Ln=Dy³⁺ (CP 1 ), Er³⁺ (CP 2 )} and [{Gd₂(L)₂(H₂O)₃}^.H₂O]_n, (CP 3 ) were hydrothermally synthesized using phosphonoacetic acid as a linker. Structural features revealed that the dinuclear Ln³⁺ nodes were present in the 2D sheet of CP 1 and CP 2 while in the case of CP 3 , nodes were further connected to each other forming a chain‐type arrangement throughout the network. The magnetic studies show field‐induced slow magnetic relaxation property in CP 1 and CP 2 with U_eff values of 72 K (relaxation time, τ₀=3.05×10^?7 s) and 38.42 K (relaxation time, τ₀=4.60×10^?8 s) respectively. Ab‐initio calculations suggest that the g tensor of Kramers doublet of the lanthanide ion (Dy³⁺ and Er³⁺) is strongly axial in nature which reflects in the slow magnetic relaxation behavior of both CPs. CP 3 exhibits a significant magnetocaloric effect with ?ΔS_m=49.29 J kg^?1 K^?1, one of the highest value among the reported 2D CPs. Moreover, impedance analysis of all the CPs show high proton conductivity with values of 1.13×10^?6 S cm^?1, 2.73×10^?3 S cm^?1 and 2, 6.27×10^?6 S cm^?1 for CPs 1 – 3 , respectively, at high temperature (>75 °C) and maximum 95 % relative humidity (RH).     

13C and 15N CP/MAS, 1H–15N SCT CP/MAS and FTIR spectroscopy as tools for qualitative detection of the presence of zwitterionic and non‐ionic forms of ansa‐macrolide 3‐formylrifamycin SV and its derivatives in solid state

¹³C, ¹⁵N CP/MAS, including ¹H–¹³C and ¹H–¹⁵N short contact time CP/MAS experiments, and FTIR methods were applied for detailed structural characterization of ansa‐macrolides as 3‐formylrifamycin SV (1) and its derivatives (2–6) in crystal and in powder forms. Although HPLC chromatograms for 2/CH₃OH and 2/CH₃CCl₃ were the same for rifampicin crystals dissolved in respective solvents, the UV–vis data recorded for them were different in 300–375 nm region. Detailed solid state ¹³C and ¹⁵N CP/MAS NMR and FTIR studies revealed that rifampicin (2), in contrast to 3‐formylrifamycin SV (1) and its amino derivatives (3–6), can occur in pure non‐ionic or zwitterionic forms in crystal and in pure these forms or a mixture of them in a powder. Multinuclear CP/MAS and FTIR studies demonstrated also that 3–6 derivatives were present exclusively in pure zwitterionic forms, both in powder and in crystal. On the basis of the solid state NMR and FTIR studies, two conformers of 3‐formylrifamycin SV were detected in powder form due to the different orientations of carbonyl group of amide moiety. The PM6 molecular modeling at the semi‐empirical level of theory, allowed visualization the most energetically favorable non‐ionic and zwitterionic forms of 1–6 antibiotics, strongly stabilized via intramolecular H‐bonds. FTIR studies indicated that the originally adopted forms of these type antibiotics in crystal or in powder are stable in standard laboratory conditions in time. The results presented point to the fact that because of a possible presence of two forms of rifampicin (compound 2), quantification of the content of this antibiotic in relevant pharmaceuticals needs caution. Copyright © 2013 John Wiley & Sons, Ltd.     

Enhanced and Optically Switchable Proton Conductivity in a Melting Coordination Polymer Crystal

The melting behavior of a coordination polymer (CP) crystal was utilized to achieve enhanced and optically switchable proton conductivity in the solid state. The strong acid molecules (triflic acid) were doped in one‐dimensional (1D) CP, [Zn(HPO₄)(H₂PO₄)₂](ImH₂)₂ (ImH₂=monoprotonated imidazole) in the melt state, and overall enhancement in the proton conductivity was obtained. The enhanced proton conductivity is assigned to increased number of mobile protons and defects created by acid doping. Optical control over proton conductivity in the CP is achieved by doping of the photo acid molecule pyranine into the melted CP. The pyranine reversibly generates the mobile acidic protons and local defects in the glassy state of CP resulting in the bulk switchable conductivity mediated by light irradiation. Utilization of CP crystal in liquid state enables to be a novel route to incorporate functional molecules and defects, and it provides a tool to control the bulk properties of the CP material.     

Study of chemically inequivalent N(CH3)4 ions in [N(CH3)4]2ZnBr4 near the phase transition temperature using 1H MAS NMR, 13C CP/MAS NMR,and 14N NMR

The temperature dependences of the chemical shifts and intensities of ¹H, ¹³C, and ¹⁴N nuclei in tetramethylammonium tetrabromozincate, [N(CH₃)₄]₂ZnBr₄, were investigated using single-crystal nuclear magnetic resonance (NMR) and magic angle spinning (MAS) NMR spectroscopy to elucidate the structural geometry near the phase transition temperature. Based on the analysis of the ¹³C cross-polarization (CP)/MAS NMR and ¹⁴N NMR spectra, the two chemically inequivalent N(1) (CH₃)₄ and N(2) (CH₃)₄ ions were distinguished. Furthermore, the ¹⁴N NMR spectrum at the phase transition temperature indicated the existence of the ferroelastic characteristics of the N(CH₃)₄ ions.     

Synthesis and Characterization of UV-Curable Poly(dimethylsiloxane) Dimethacrylate

This paper presents a new route to the synthesis of UV-curable poly(dimethylsiloxane) dimethacrylate (PDMSDMA). PDMSDMA was essentially prepared by modification of poly(dimethylsiloxane), bis(3-aminopropyl) terminated (PDMS-NH₂) with methacrylic anhydride (MAA). The synthesized products were cured under UV in the presence of camphorquinone (CQ) used as a photoinitiator. The chemical structure of PDMSDMA samples was analyzed by FT-IR and ¹H-NMR spectroscopy. The ¹H-NMR spectrum of PDMSDMA revealed new peaks at 3.20 ppm, corresponding to methylene protons in  CH₂ NH , and 5.25 and 5.65 ppm, corresponding to vinylic protons in  NH CO CCH₃CH₂. The chemical structure of the cured products and the degree of curing were determined by solid state ¹³C CP/MAS NMR and FT-IR (Micro-ATR) spectroscopy. Various parameters, such as concentration of methacrylic anhydride, amount of camphorquinone, and curing time, were studied.     

Interaction and Scale of Mixing in Cellulose Acetate/Poly(<Emphasis Type="Italic">N</Emphasis>-vinyl Pyrrolidone-co-vinyl Acetate) Blends

Binary blends and pseudo complexes of cellulose acetate (CA) with vinyl polymers containing N-vinyl pyrrolidone (VP) units, poly(N-vinyl pyrrolidone) (PVP) and poly(N-vinyl pyrrolidone-co-vinyl acetate) [P(VP-co-VAc)], were prepared, respectively, by casting from mixed polymer solutions in N,N-dimethylformamide as good solvent and by spontaneous co-precipitation from solutions in tetrahydrofuran as comparatively poor solvent. The scale of miscibility and intermolecular interaction were examined for the blends and complexes by solid-state ¹³C-NMR spectroscopy. It was revealed that the formation of complexes was due to a higher frequency of hydrogen-bonding interactions between the residual hydroxyl groups of CA and the carbonyl groups of VP residues in the vinyl polymer component. From measurements of CP/MAS spectra and proton spin-lattice relaxation times (T_1ρ^H) in the NMR study, the existence of the hydrogen-bonding interaction was also confirmed for the miscible blends and the homogeneity of the mixing was estimated to be substantially on a scale within a few nanometers.     

Structural studies on lithocholyl-N-(2-aminoethyl)amide in the solid state

The synthetic procedure of lithocholyl-N-(2-aminoethyl)amide yielded a mixture of several forms detected by solid state ¹³C CP/MAS NMR although the solution state NMR unambiguously ascertained that the compound was pure. By recrystallization from various solvents one pure polymorph alongside with four solvates were isolated. The structures of the pure polymorph and the solvates were characterized by ¹³C and ¹⁵N CP/MAS NMR and powder X-ray diffraction (PXRD) methods. Variable contact time and dipolar dephasing experiments were employed to obtain optimized CP parameters and to distinguish various CH _n (n = 0–3) resonances. CSA analyses of spinning side bands at different spinning rates showed small variations in the shielding tensor values of the carbonyl group between the pure polymorph (recrystallized from acetonitrile, tetrahydrofuran and 1,4-dioxane) and p-xylene solvate.     

The preparation of polysiloxane xerogels containing amide derivatives of phosphonic and thiophosphonic acids in the surface layer

Xerogels containing residues of amide derivatives of phosphonic and thiophosphonic acids, ≡Si(CH₂)₃NHP(S, O)(OC₂H₅)₂ (functional group concentration of 1.3–2.2 mmol/g) have been prepared by a sol-gel method. It has been shown that xerogels having a developed porous structure (with specific surface areas of 240–485 m²/g, pore volumes of 0.20–0.50 cm³/g, and pore diameters of 3.6–6.5 nm) are formed at tetraethoxysilane-to-trifunctional silane ratios of 4: 1 (and above) and 6: 1 (and above) for the derivatives of phosphonic and thiophosphonic acids, respectively. The IR and ¹³C CP/MAS NMR spectroscopy data have demonstrated that the surface layer of the xerogels contains not only (thio)phosphonic acid residues, but also silanol groups and water molecules participating in hydrogen bonding. The ²⁹Si CP/MAS NMR spectroscopy data have indicated that structural groups are, for the most part, contained in structural units T³ [(≡SiO)₃Si(CH₂)₃NHP(O, S)(OC₂H₅)₂] and T² [(≡SiO)₂Si(OR)[(CH₂)₃NHP(O, S)(OC₂H₅)₂] (R = H or C₂H₅).     

Electronic structures and NMR of some hydroxycarbonium ions

The proton and isotropic (¹³C) magnetic resonances of some hydroxycarbonium ions (HCHOH⁺, CH₃CHOH⁺ (CH₃)₂COH⁺ HCO₂H₂⁺, CH₃CO₂H₂⁺, and CH₃OH₂⁺) are discussed in relation to their electronic structures computed by means of the INDO—SCF method. The proton and carbon-13 chemical shifts, which depend directly on the local diamagnetic and paramagnetic contributions respectively, are reasonably explained by the electronic structures of the hydroxycarbonium ions relative to those of the corresponding parent molecules. The Fermi contact interaction term is found to be well reflected in the hydrogen-hydrogen and carbon-hydrogen coupling constants, and the differences in the coupling constants between rotational isomers of the ions are discussed from the viewpoint of their electronic properties.     

Vinylimidazole copolymers: coordination chemistry,solubility, and cross-linking as function of Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> complexation

P(1-VIm-co-MMA) copolymers with 4 or 44 wt.% 1-VIm (abbreviated PVM-4 and PVM-44) where polymerized from 1-VIm (1-vinylimidazole) and methylmethacrylate with azobisisobutyronitrile as initiator and reacted with either Cu²⁺ or Zn²⁺. The resulting coordinated polymer complexes were studied using ICP-AES, CP/MAS ¹³C NMR, conductivity measurements, vibrational spectroscopy (mid-FTIR and far-FTIR), DSC, and EPR. It was established by ICP-AES, CP/MAS ¹³C NMR, conductivity, mid-FTIR and EPR measurements that the transition metal ions in the complexes were exclusively coordinated by the imidazole ligand. The coordination geometry is square planar with regard to Cu(II) complexes. The strong interaction between the polymeric imidazole ligand and the transition metal ion cross-links the system, resulting in augmentation of T _g (the glass transition temperature), especially for copolymers with high relative amount of 1-VIm. The effect of changing metal ion is more complicated and depends on both the strength of the coordinate interaction as well as the coordination number. The solubility of the coordinate polymer complex in conventional solvents is low due to the coordinate cross-links. However, the coordinate polymer complexes are soluble in strongly coordinating solvents such as acetonitrile and dimethylsulfoxide.     

ENZYMATICALLY SYNTHESIZED POLYANILINE IN THE PRESENCE OF A TEMPLATE POLY(VINYLPHOSPHONIC ACID): A SOLID STATE NMR STUDY

Template guided enzymatic synthesis of conducting polyaniline (PANI) is a one-step reaction and more importantly, it is an environmentally friendly process. Understanding of the reaction and coupling mechanism at the molecular level is of paramount significance to improve its processability and conductivity. Solid-state NMR techniques are useful to investigate molecular structures of enzymatically synthesized polyaniline (PANI). The PANI sample in three different forms i.e., (a) as-synthesized, self-doped conducting form; (b) dedoped, base form and; (c) redoped, conducting form, are investigated by solid-state ¹³C and ¹⁵N CP/MAS NMR techniques. Solid-state NMR data analysis shows that the structural features of enzymatically synthesized PANI are similar to that of chemically synthesized PANI. The solid-state ¹³C CP/MAS NMR spectrum of the base form of PANI confirmed that benzenoid-quinoid repeating units are present in the backbone of the PANI polymer chain. The poly(vinylphosphonic acid) (PVP) template provides charge compensation during the chain growth of linear polyaniline. After the completion of template-guided synthesis of PANI, it is now possible that the PVP template can be completely removed from the complex by dedoping with aqueous NH₄OH. The detached PANI from the PANI-PVP complex can then be redoped to conducting form without the presence of the template. The conductivity of the PANI and PANI-PVP complex are of the same order of magnitude. The solid-state ¹⁵N CP/MAS NMR chemical shifts are sensitive to charge distribution on the nitrogens in the backbone. The solid-state ¹⁵N CP/MAS NMR spectrum of the base form of the enzymatically derived PANI sample showed the clear signature for benzenoid-quinoid repeating units in the polymer backbone.

     

NMR Microscopy of an “Anisotropic” Polymer

Two different samples of high-density polyethylene (HDPE) have been studied. One (isotropic) is extracted from the material core whereas the other (anisotropic) involves two sides which have been in contact with the injection mold. It is observed by NMR microscopy (using radiofrequency field gradients) that these two sides favor toluene penetration into the material. The distribution of toluene nuclear spin relaxation times (extracted from proton T₁ and T₂ images) exhibits likewise important differences between the two samples. These differences can be accounted for by partial molecular ordering at the vicinity of the “mold sides”. Finally, in investigating the anisotropic sample (without solvent), three different phases (two amorphous and one crystalline) are revealed by ¹³C chemical shift imaging experiments (performed with radiofrequency field gradients under CP/MAS conditions). Each amorphous component is preferentially present at one of the two “mold sides”.     

Proton conduction of MO-P2O5 glasses (M = Zn,Ba) containing a large amount of water

Zinc and barium phosphate glasses show good proton conductivity at intermediate temperature around 200 °C. Infrared spectra and ¹H magic angle spinning-nuclear magnetic resonance (MAS–NMR) spectra proposed that a 30 mol%ZnO-70 mol%P₂O₅ glass melted at 800 °C has a large amount of ‘mobile’ protons. The proton conductivity at 250 °C was measured to be 1 × 10⁻³ S/cm. A H₂-air fuel cell using the ZnO–P₂O₅ glass electrolyte of 1.8 mm in thickness showed the maximum power density of 1.2 mW/cm² at 200 °C.