Proton conductivity of calix[n]arene-para-sulfonic acids (n = 4, 8)

High proton conductivity in calix[n]arene-para-sulfonic acid hydrates (n = 4, 8) reaching a value of 10^?1 Ohm^?1 cm^?1 at a relative humidity of 80% was revealed for the first time. This value is close to the record conductivity of solid proton conductors and acid water solutions. The dependence of proton transfer parameters and water quantity in the title compounds dependent on the relative humidity of air was investigated.     

Synthesis and characterization of a new trans-2,2′-azoquinoxaline bridged bisphthalocyanine

A new trans-2,2′-azoquinoxaline bridged bisphthalocyanine was synthesized from the corresponding quinoxaline-2(1H)-one oxime, which can be obtained by the reaction of s-trans-chloroethanedial with 2-(3,4-diaminophenoxy)-9,16,23-tri(hexylthio)phthalocyanine zinc(II). 2-(3,4-Diaminophenoxy)-9,16,23-tri(hexylthio)phthalocyanine zinc(II) was synthesized by reduction of 2-(4-amino-3-nitrophenoxy)-9,16,23-tri(hexylthio)phthalocyanine zinc(II). Novel compounds were characterized by elemental analysis, UV/vis, IR and ¹H NMR spectroscopy. The conductivity and the humidity sensing properties of spin coated films of these compounds were investigated by measuring the complex impedance spectra at different humidities. Films of the final product show up to 10³ orders of magnitude higher conductivity than the starting and intermediate compounds. The results indicate that the presence of water vapour always leads to a drop in the real and imaginary part of the complex impedance. At room temperature, the capacitance of the films exhibits reversible increase with relative humidity, which makes these films attractive for humidity sensing applications.     

A new high-temperature inorganic–organic proton conductor: lanthanum sulfophenyl phosphate

Lanthanum sulfophenyl phosphate (LaSPP) was synthesized by m-sulfophenyl phosphonic acid and lanthanum nitrate. UV-Vis spectrophotometry and Fourier-transform infrared spectroscopy indicate that the desired product was obtained and its elementary composition and typical layered structure were determined by energy dispersive X-ray spectroscopy and scanning electron microscopy. Transmission electron microscopy (TEM) proved its typical layered structure and X-ray diffraction spectroscopy indicated its good crystallinity and the interlayer distance of about 15.67 Å, which matches the value obtained by TEM (2.0 nm). Thermogravimetry and differential thermal analysis revealed good thermal stability of LaSPP. Proton conductivity of LaSPP was measured at different temperatures and relative humidities (RH), reaching values of 0.123 S cm^?1 at 150°C and 100 % RH. Proton transfer activation energy was 22.52 kJ mol^?1. At 160°C and 50 % RH, the conductivity was 0.096 S cm^?1. In the drying oven, the conductivity retained the value of 1.118 × 10^?2 S cm^?1. The results show that LaSPP is a highly effective inorganic-organic conductor.     

Mechanism of ion transport in hybrid materials based on MF-4SC perfluorinated sulfonation-exchange membranes and acid zirconium phosphate nanoparticles

The relationship between the transport properties of various salt forms (H⁺, Li⁺, Na⁺, Cs⁺) of MF-4SC hybrid membranes containing nanoparticles of crystalline acid zirconium phosphate Zr(HPO₄)₂ at various relative humidities are investigated with the use of impedance studies and NMR spectroscopy. Modification of the membranes leads to a marked increase in ion mobility, and the maximum effect is observed under reduced humidity conditions. The conductivity of a modified membrane at a relative humidity of 10% is 1.6 × 10^?4 Ω^?1 cm^?1, that is, almost 1.5 orders of magnitude greater than the conductivity of an initial membrane under the same conditions.     

PEO-12-钨磷酸质子导电聚合物电解质膜

以聚氧乙烯(PEO)为基质, 在其中掺杂适量的钨磷酸, 制备PEO-H₃PW₁₂O₄₀质子导电聚合物电解质膜. XRD及IR测试表明体系中Keggin阴离子与PEO链相互作用形成新的化合物; Keggin阴离子的存在有利于水合质子的形成. PEO-H₃PW₁₂O₄₀复合膜的电导率室温最高可达4.0×10^－3 S•cm^－1.     

Synthesis and Characterization of Polyelectrolyte Complex N-Succinylchitosan-chitosan for Proton Exchange Membranes

Synthesis of acid-base complex membrane is one of method to improve the proton conductivity in proton exchange membrane for fuel cell applications. In this study, acid-base complex membrane was synthesized based on N-succinylchitosan-chitosan complexes. The N-succinylchitosan was blended with chitosan in acetic acid at various substitution degree of N-succinylchitosan with weight ratio of N-succinylchitosan of 80% w/w. The acid-base complex membranes were cast from the polymer solution and dried by evaporation. The properties of the membranes such as water uptake, ion exchange capacity, proton conductivity, and mechanical strength were analyzed. It was observed that the increase of substitution degree of N-succinylchitosan tends to increase the proton conductivity. The optimum performance of membrane unit is attained by the substitution degree of N-succinylchitosan of 0.72, which is reflected by its ion exchange capacity of 3.45 meq/g and proton conductivity of 7.35 × 10^-2 S cm^-1, respectively. Blending of N-succinylchitosan and chitosan also improved the mechanical strength of the membranes. These results imply that this type of polyelectrolyte complex membrane is a good candidate for proton exchange membrane in fuel cell applications.     

Fluorinated polyoxadiazole for high-temperature polymer electrolyte membrane fuel cells

For the first time a fluorinated polyoxadiazole doped with phosphoric acid as a proton-conducting membrane for operation at temperatures above 100 °C and low humidities for fuel cells has been reported. Fluorinated polyoxadiazole with remarkable chemical stability was synthesized. No changes in the molecular weight (about 200,000 g mol⁻¹) can be observed when the polymer is exposed for 19 days to mixtures of sulfuric acid and oleum. Protonated membranes with low doping level (0.34 mol of phosphoric acid per polyoxadiazole unit, 11.6 wt.% H₃PO₄) had proton conductivity at 120 °C and RH = 100% in the order of magnitude of 10⁻² S cm⁻¹. When experiments are conducted at lower external humidity, proton conductivity values drop an order of magnitude. However still a high value of proton conductivity (6 × 10⁻³ S cm⁻¹) was obtained at 150 °C and with relative humidity of 1%. In an effort to increase polymer doping, nanocomposite with sulfonated silica containing oligomeric fluorinated-based oxadiazole segments has also been prepared. With the addition of functionalized silica not only doping level but also water uptake increased. For the nanocomposite membranes prepared with the functionalized silica higher proton conductivity in all range of temperature up to 120 °C and RH = 100% (in the order of magnitude of 10⁻³ S cm⁻¹) was observed when compared to the plain membrane (in the order of magnitude of 10⁻⁵ S cm⁻¹).     

Hydration of the H<Superscript>+</Superscript>, Li<Superscript>+</Superscript>, Na<Superscript>+</Superscript>, and Cs<Superscript>+</Superscript> ions in MF-4SK perfluorinated sulfonic acid cation-exchange membranes modified with inorganic dopants

The hydration, state, and mobility of protons and Li⁺, Na⁺, and Cs⁺ ions in MF-4SK perfluorinated sulfonic acid cation-exchange membranes doped with silicon dioxide and phosphotungstic acid have been investigated by NMR and impedance spectroscopy. The dopants increase the moisture content of the membrane and change the system of pores and channels in which ion transport takes place. At low humidities, the dopant particles are involved in ion transport. The greatest effect is observed for the membranes doped with both SiO₂ and phosphotungstic acid. The water molecules sorbed by dopant particles as a material participate in the hydration of alkali metal cations in the membrane.     

Synthesis and study of a polymer containing di- and triazenyl-p-phenylene groups

A polymer containing di- and triazenyl-p-phenylene groups in the main chain was synthesized for the first time. Doping of newly synthesized poly(triazene-1,3-diyl-p-phenylenes) and poly(triazene-1,3-diyl-pdiphenylenes) with perchloric acid is studied. The introduction of azophenylene groups in the chain of a polymer containing triazenylphenylene groups has almost no effect on electrical conductivity. The electrical conductivity of these polymers increases from 10^?9 to 0.8 S/m with increasing doping degree. The replacement of phenylene by diphenylene groups slightly reduces the electrical conductivity of the polymer doped with perchloric acid, while in the case of iodine doping, by contrast, the electrical conductivity slightly increases.     

Electrical field influence on molecular mass and electrical conductivity of polyaniline

We have described the primary studies on the conductivity and molecular weight of polyaniline in an electric field as it is used in a field effect experimental configuration. We report further studies on doped in-situ deposited polyaniline. First we have chemically synthesized polyaniline by ammonium peroxodisulfate in an acidic solution, with aqueous, organic and emulsion conditions at different times. Next, we measured mass and conductivity and obtained the best time of polymerizations. Then, we repeated these reactions under different electrical fields in constant time and measured mass and conductivity. The polyaniline is characterized by gel permeation chromatography (GPC), UV-visible spectroscopy and electrical conductivity. Polyanilines with high molecular weight are synthesized under electric field M _w = (5.2–6.8) × 10⁵, with M _w/M _n = 2.0–2.5. The UV-visible spectra of polyanilines oxidized by ammonium peroxodisulfate and protonated with dodecylbenzenesulfonic acid (PANi-DBSA), in N-methylpyrolidone (NMP) show a smeared polaron peak shifted into the visible. Electrical conductivity of polyaniline has been studied by four-probe method. The conductivity of the films of emeraldine protonated by DBSA cast from NMP is higher than 500 S/cm under (10 kV/cm² of potential) electric field and shows an enhanced resistance to ageing. Next, we carried chemical polymerization at the best electric field at different times. Finally, the best time and amount of electric field were determined. Polymers synthesized under an electric field probably have better physical properties regarding the existence of less branching and high electric conductivity.     

Thermal transport characteristics of polypropylene fiber-based knitted fabrics

Thermal comfort is condition of an organism, when there is no sweating and the mean skin temperature is in the range from 32 to 34?°C (Hes, Measurement of comfort, What can textile III, 2009). Thermal comfort is closely connected with the following characteristics: thermal resistivity and thermal conductivity. Related properties are: resistance against the penetration of water vapor, air permeability, and porosity. The thermal resistivity R (W^?1?K?m²) and thermal conductivity K (W?K^?1?m^?1) of knitted fabrics containing PP fiber were measured. Measurements were realized on three different types of devices. The experimental results were compared with simple mechanistic model for prediction of thermal conductivity K for textile structures.     

Proton conductivity of calix[4]arene-para-sulfonic acids

The proton conductivity of hydrates of calix[4]arene-para-sulfonic acids is studied. The high proton conductivity is observed at ambient temperatures in the wide ranges of environmental humidity and, correspondingly, water content in the hydrate. For the air humidity of 10 rel. %, the conductivity of compounds is 10^?4-10^?3 S cm^?1 and approaches 10^?2-10^?1 S cm^?1 as the humidity increases up to 70 rel. %.     

Studies on the adsorption of nitrogen dioxide onto manganese dioxide-coated quartz piezoelectric crystals

A technique for obtaining thin; evenly distributed manganese dioxide coatings by melting manganese nitrate is outlined. Responses of an AT-cut quartz piezoelectric crystal coated with manganese dioxide to nitrogen dioxide (12.5-10 000 μl 1^?1) over a range of humidities (400–4,800 μ1 l^?1 water) and temperatures (20–35 °C) are given. The response of the simulated product manganese nitrate, over the same range of humidities, is evaluated in relationship to real product formation. The approach may be applicable to other metal salt/metal oxide systems. The detection limit is 7 μl^?1 nitrogen dioxide.     

The preparation of conducting polyaniline�Csilver and poly(p-phenylenediamine)�Csilver nanocomposites in liquid and frozen reaction mixtures

The oxidation of aniline with silver nitrate in 1?mol?L^?1 acetic acid at 20?°C yielded a composite of two conducting components, polyaniline and silver; the acceleration with 1?mol% of p-phenylenediamine is needed for efficient synthesis. The yield and molecular weight increased when aniline was copolymerized with 10?mol% p-phenylenediamine. Such product displayed metallic conductivity below 180?K and semiconductor type above this temperature. As the result, the conductivity was the same at 100 and 300?K. The oxidation of p-phenylenediamine alone with silver nitrate also produced a conducting composite having the conductivity of 1,750?S cm^?1 despite the assumed nonconductivity of poly(p-phenylenediamine). The present study demonstrates that all oxidations proceeded also in frozen reaction mixtures at ?24?°C, i.e., in the solid state. In most cases, molecular weights of polymer component increased, the conductivity of composites with silver improved, to 2,990?S?cm^?1 for poly(p-phenylenediamine)?Csilver, and remained high after deprotonation with 1?mol?L^?1 ammonium hydroxide.     

Crosslinking effects on hybrid organic–inorganic proton conducting membranes based on sulfonated polystyrene and polysiloxane

New hybrid semi‐interpenetrating proton‐conducting membranes were obtained using sulfonated polystyrene (SPS) and inorganic–organic polysiloxane phases with the aim of improving the mechanical and thermal characteristics of the pristine polymer and to study the effects of crosslinking in the latter phase in several of their properties, mainly proton conductivity. Siloxane phases were prepared using poly(dimethylsiloxane) (PDMS) and PDMS with tetraethoxysilane (TEOS) or phenyltrimethoxysilane (PTMS) as crosslinking agents. To study the crosslinking effect, membranes were prepared with different TEOS:PDMS and PTMS:PDMS mole ratios. The films obtained were characterized by FTIR, ²⁹Si‐HPDEC MAS‐NMR, ¹³C‐CP‐MAS NMR, elemental and thermal analyses. Certain properties, such as water uptake (WU), ion exchange capacity (IEC) and the state of the water, were determined. The proton conductivity was measured at different temperatures (30°C and 80°C) and relative humidities (50–95%). The water content of the hybrid membranes declined significantly, compared with the SPS membranes, depending on the nature and amount of siloxane phase added. Nonetheless, the conductivity values remained relatively high (>100 mS cm^?1 at 80°C and 95% RH) when compared to Nafion®117 presumably because of the formation of well developed proton channels, which makes them potentially promising as proton exchange membranes for fuel cells. These membranes proved to be thermally stable up to 350°C. Scanning electron microscopy (SEM) and scanning electrochemical microscopy (SECM) were used to characterize the hybrid membranes microstructures; the latter provided contrast for the conductive domains. Copyright © 2015 John Wiley & Sons, Ltd.     

Physical–chemical study of water in contact with a hydrophilic polymer: Nafion

The study detailed in this paper is about the determination of the physical–chemical parameters of water, after keeping it in prolonged contact with the Nafion polymer. The parameters under study are: electrical conductivity, χ (μS cm^?1); heat of mixing with acid (HCl), ΔQ _mix ^HCl (J kg^?1) or basic (NaOH) solutions, ΔQ _mix ^NaOH  (J kg^?1), and pH. χ increases of up to two orders of magnitude, ΔQ _mix ^NaOH  (J kg^?1) is exothermic and increases as the electrical conductivity increases, with a roughly linear trend, up to one order of magnitude. The analogous ΔQ _mix ^HCl  (J kg^?1), on the contrary, is found to be null. The pH is quite acid and shows a very good linear correlation with log χ. The linear correlations hint at a single cause for the variation of the three very different physical–chemical parameters. This complex and hard to rationalize phenomenology, finds a good theoretical support in the work hypothesis of the formation of dissipative structures within the liquid. These are far-from-equilibrium systems outside the paradigm of classical thermodynamics. The work hypothesis of the formation of molecular aggregates of water molecules (dissipative structures, aqueous nanostructures, clusters, coherence domains, etc.) is shared with two other aqueous systems obtained with different preparation protocols, so we briefly recall them here: (1) EDS (extremely diluted solutions): obtained through an iterative process of successive dilutions and agitations. (2) IFW (iteratively filtered water): obtained through an iterative process of successive filtrations through sintered glass filters. (3) INW (iteratively nafionized water): obtained through an iterative process of successive drying and wetting of the Nafion polymer. Each protocol produces water exhibiting its own peculiarities, to the point that they can be considered different, albeit with the common element of a variation of the super-molecular structure of the water solvent. The physical–chemical properties of these perturbed waters cannot be framed by the paradigm of classical thermodynamics, but rather require the use of the thermodynamics of systems far from the equilibrium and of irreversible processes.     

Electrical properties of Ba2(In1 − x Al x )2O5 solid solutions

The electric conductivity of perovskite-like Ba₂(In_{1 ? x} Al _x )₂O₅ solid solutions (0 < x ≤ 0.20) characterized by structural disordering in the oxygen sublattice was studied as a function of temperature and partial pressure of oxygen in an atmosphere with a low content of water vapors ( $p_{H_2 O}$ = 3 × 10^?5 atm). When In³⁺ was partially replaced by Al³⁺, the oxygen ion conductivity increased because of the disordering of oxygen structural vacancies, leading to a significant increase in the total electric conductivity of the samples.     

Structure and Mobility Pattern of Proton-Containing Groups in Hydrates of Titanium,Zirconium and Tin Acid Phosphates; Their Conducting and Ion Exchanging Properties

Abstract

Phosphates of tetravalent elements are practically important for ion exchange, catalysis and conductivity. This study deals with a number of hydrates of titanium, tin and zirconium phosphates. PMR data show that the structure of water molecules in hydrates is slightly distorted, and at temperatures higher than 160 K water has high translation mobility. NMR ³¹P proves HPO² ₄ dissociation to be growing with increase of temperature. Energetic parameters of this process are determined. Close values of anion dissociation enthalpy (0, 16/2/Ev) and obtained activation energy of conductivity for di- and monohydrates (0,17/2/Ev) show tunnel pattern of proton transfer along H-bond direction, This type of correlation was not observed in anhydrous compounds. That can be explained by impossibility of anion proton tunneling because of H-bond weakening. Proton conductivity of acid phosphates was studied. Ten-fold decrease of conductivity at room temperature with the loss of each water molecule proves H₂O participation in proton transport. Mechanism of this process is discussed with the use of NMR data. Dependence of water mobility and conductivity level on the degree of crystallinity is also discussed. With the help of NMR-data processes of ion exchange in tin and zirconium acid phosphates, as well as the state of developed salt forms were studied. Presence of lithium with high mobility in Li₂Sn(PO₄)₂ ·nF₂O was established.     

Electrochemical and chemical synthesis of nanostructure copoly(aniline-o-anisidine-o-toluidine) and study of its electrochemical behavior in organic sulfonic acid media

Terpolymerization of aniline, o-anisidine and o-toluidine was carried out by electrochemical and interfacial chemical polymerization. All homopolymers and terpolymer thin films have been synthesized through electropolymerization at room temperature in aqueous solutions containing 0.5 M of organic sulfonic acid, such as p-toluene sulfonic acid, methane sulfonic acid, sulfosalicylic acid, dodecylbenzene sulfonic acid, and 0.1 M of aniline, o-anisidine and o-toluidine monomers, using cyclic voltammetry method, applying a sequential linear potential scan at a rate of 25 mV s^?1 between ?0.1 and 0.9 V. The electrochemical terpolymerization has been performed at various mole ratios of monomers. Nanoparticles obtained from conjugation of homo- and terpolymer with organic sulfonic acids, were prepared by a chemical oxidation via interfacial chemical polymerization. SEM micrographs, FTIR spectra and conductivity measurements using four-probe method were applied for the characterization of the products. Terpolymer was characterized by higher conductivity than poly-o-toluidine and lesser than polyaniline and poly-o-anisidine. The solubility of terpolymers was dependent on the monomers mole ratio.     

Enzymatic Synthesis of Semiconductor Polymers by Chloroperoxidase of Caldariomyces fumago

Among intrinsically conducting polymers, polyaniline is traditionally synthesized by chemical or electrochemical methods. Recently enzymatic synthesis of conducting polymers has been explored. In this work, polymers were synthesized using chloroperoxidase from Caldariomyces fumago and substituted anilines such as 2,6-dimethylaniline, 2,6-dichloroaniline, and 2,3,5,6-tetrachloroaniline (TCA), in order to promote a linear polymerization. These polymers were doped with (1S)-(+)-10-camphorsulfonic acid, dodecylbenzenesulfonic acid, and 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPSA) with molar ratios of 1:0.25 and 1:0.5. Doped polymers showed conductivity corresponding to the semiconductors. TCA polymer doped with AMPSA showed the higher conductivity values. Different AMPSA concentrations have been tested, and the highest conductivity value of 1.6?×?10^?2?S?m^?1 was obtained for the complex with molar ratio of 1:0.5. This value is similar to those found with other substituted anilines with sulfonic groups. In addition, the enzymatically synthesized polymeric film showed combined transparency and semiconducting properties.