Spectrophotometric Determination of Zirconium in Monazite Sand

A sensitive spectrophotometric method was developed for the determination of zirconium in monazite sand. The zirconium ion was previously separated from the other interfering elements by a 0.5 M thenoyltrifluoroacetone (TTA)-xylene extraction, then determined with Arsenazo III in 9 M HCl medium. Zirconium reacted with Arsenazo III to form an emeraled green coloured complex having maximum absorbance at 665 nm in 9 M HCl medium. The color was stable for at least 2 hours. Effects of time, HCl concentration, gelatine and various ions have been studied. The system confirms the Beer's law over the concentration range investigated. Optimum condition range for measurement in 1.0 cm quartz cell is 0.1–0.5 μg/ml of zirconium. The molar absorptivity is 1.51×10⁵ liter mole^?1 cm^?1. The metal-ligand ratio of 1:4 was confirmed by Job's Continuous Variation method and the conditional stability constant of Zirconium-Arsenazo III Complex in 4 M HCl and 9 M HCl were also determined by this method.     

Chemical preparation of conductive elastomeric blends: Polypyrrole/EPDM. I. Oxidant particle-size effect

This work describes the preparation of polypyrrole and EPDM rubber blends, PPy/EPDM, by the sorption of pyrrole (vapor phase) in an EPDM matrix containing CuCl₂. We investigated the effect of the oxidant particle-size on the sorption and polymerization equilibrium, electrical conductivity, and mechanical properties of the blends. Independently of the CuCl₂ concentration and polymerization time, the polypyrrole weight fraction in the blend, X_ppy, increases when the oxidant particle-size in changed from 150–250 μm to smaller than 106 μm. For blends containing 50 phr of CuCl₂, obtained following 72 h of exposure to pyrrole, an increase in the Young's Modulus (from 2.2 ± 0.2 to 3.9 ± 0.6 MPa) and an increase in the electrical conductivity (from 10^?9 to 10^?7 S cm^?1) was observed when the oxidant particle-size was decreased. Infrared spectroscopy, thermogravimetric analysis, scanning differential calorimetry, and scanning electron microscopy were used in sample characterization. © 1994 John Wiley & Sons, Inc.     

Electrical and mechanical properties of the zone-drawn polypyrrole films

The zone-drawing method (ZD) was applied to electrochemically synthesized polypyrrole films containing tosylate (PPy/TsO) and the mechanical and electrical properties of the resulting films were investigated. It was found that the electrical conductivity of the zone-drawn film reached 365 S cm⁻¹ in the drawing direction, which was 4.7 times that of the original film. The tensile properties of the zone-drawn film were improved and Young's modulus and strength at break increased to 4.32 GPa and 90.1 MPa from 0.53 GPa and 40.4 MPa of the as-synthesized film, respectively. The dynamic storage modulus (E) increased by the zone-drawing over a whole experimental temperature range and attained 7.0 GPa at room temperature and 4.0 GPa even at 200°C. © 1996 John Wiley & Sons, Inc.     

Synthesis and characterization of poly[2,5-bis(triethoxy)-1,4-phenylene vinylene]

The synthesis of a highly soluble, 2,5-disubstituted poly(p-phenylene vinylene) with pendant side chains containing ether groups was accomplished by a dehydrochlorination route. Specific interactions of the oxygen-containing side chains with the solvent are presumably responsible for the high solubility of the polymer, especially in protogenic solvents. The polymer microstructure was characterized by ¹H- and ¹³C-NMR. The polymer showed solvatochromic properties when dissolved in a variety of solvents. The relatively high molecular weight (M_n = 17,000) permitted the fabrication of free-standing films. The electrical conductivity of iodine-doped films was approximately 2 × 10^–2 S cm^–1. © 1995 John Wiley & Sons, Inc.     

X-ray photoelectron spectroscopic investigation of conducting polymer blends

Electrochemically prepared films of conducting polymers of polypyrrole and polythiophene and their blends with polyamide have been investigated by X-ray photoelectron spectroscopy. In the N1s region of the spectra of films containing polypyrrole the peak corresponding to N⁺ at 402.0 eV is separated from that of neutral N. The intensity of the N⁺ peak can be correlated with the electrical conductivity of the films and the spectroscopically derived ratio of F/N⁺ is close to 4 indicating that one BF^-₄ dopant ion is incorporated for every oxidized nitrogen center. In the spectra of films of polythiophene and its blends peaks corresponding to S and S⁺ can not be resolved but again the F/C ratio correlates with the electrical conductivity.     

Highly Conductive Polypyrrole Copolymers?

In a recent publication by Akar and co‐workers (Eur. Polym. J. 2006 , 42, 2361), it was claimed that bulk polypyrrole with a conductivity of 4 000 S · cm⁻¹ was obtained by a simple chemical synthesis. If reproducible, this would be a quite revolutionary result for the polymer electronics community. In this communication, we report that this result is not reproducible, and demonstrate, by comparison to literature results, that it is also not plausible.     

Electrical conductivity of poly(vinyl chloride) obtained by photodehydrochlorination from laminated poly(vinyl chloride)/polypyrrole films

Poly(vinyl chloride) (PVC) has been converted to an electrically conductive structure by combined electrochemical and photochemical methods. PVC was cast on a polypyrrole (PPy) film electrode which had been electrochemically prepared. The PVC layer in the laminated PVC/PPy films was first dehydrochlorinated under the illumination of UV light, and the generated polyenes were subsequently doped with I₂ and FeCl₃. The maximum electrical conductivity achieved for such PVC film was 2.51 X 10^?2 and 8.63 10^?2 S cm^?1 after I₂ and FeCl₃ doping, respectively. The temperature dependence of the electrical conductivity showed different behavior in higher and lower temperature ranges. In the former (T > 243 K), the T^?1 law held, and the activation energy and bandgap were estimated as 0.25 and 0.49 eV, respectively. In the latter (T < 243 K), the conductivity mechanism followed the variable range hopping model (T^?1/4 law) in which the radius of the localized state wave function and the density of the localized states at the Fermi level were 1.25 × 10³ Å and 1.03 X 10¹⁵ eV^?1 cm^?3, respectively. © 1995 John Wiley & Sons, Inc.     

Correlation between IR spectra and electric conductivity of polyethylene-polypyrrole composites

Composite systems prepared via polymerization of pyrrole on PE porous films were studied by conductivity measurements and FTIR spectroscopy. The conductivity of samples was varied via dedoping of polypyrrole. The low-frequency edges of electronic absorption bands of quasi-particles responsible for the conductivity in polypyrrole appear in the IR spectral region. The total absorption is observed in the region of 650–15000 cm^?1 for the samples with a conductivity of 1–10 S/cm. A correlation was revealed between the position of the total absorption edge and the conductivity: the total absorption edge shifts to higher frequencies with a decrease in conductivity. On the basis of the data obtained, a model of the electronic structure of conductive polypyrrole is proposed.     

Structural and electrical characterisation of betaine-type,organic, molecular,thin evaporated films and LB multilayers

The structure and electrical properties of highly polar indandione-1,3 pyridinium betaine (IPB) derivatives have been studied in vacuum-evaporated thin films and Langmuir-Blodgett (LB) multilayer assemblies. Phase transitions induced by temperature and/or electric field have been observed in LB films of an amphiphilic derivative of IPB.The LB films of IPB, obtained at room temperature, form a Y-like structure which melts at about 50 °C to produce spherical domains, having Z-like structure, which remain stable up to 110 °C. Similar phase transitions can be induced by an electric field with ε ≥ 2 × 10⁵ V cm⁻¹ at room temperature. In the new Z-like phase of the IPB LB films, the electrical conductivity increases by some five or six orders of magnitude and the activation energy of dark conductivity decreases from 0.18 ± 0.03 eV to practically zero.The vacuum-evaporated IPB films yield low electrical conductivity (σ = 10⁻¹⁵–10⁻¹⁶S cm⁻¹), whereas in the LB multilayers a notable anisotropy of conductivity is observed. In case of coplanar cells the conductivity increases to σ = 10⁻⁸S cm⁻¹. In sandwich-type LB samples the conductivity value is similar to that of the vacuum-evaporated polycrystalline thin films.     

Conductive polymers as a new type of thermoelectric material

Thermoelectric properties were investigated for the films of electrically conductive doped polyanilines. The thermoelectric performance, evaluated by thermoelectric figure-of-merit (ZT = T (S² σ) / κ), of various protonic acid-doped polyaniline bulk films was found to depend on the electrical conductivity σ of the film. Thus, the higher the electrical conductivity, the higher the figure-of-merit is, because the thermal conductivity κ of polyaniline films does not depend on the electrical conductivity. Among the conductive bulk films of polyaniline, the highest figure-of-merit (ZT = 1 × 10⁻⁴) was observed for (±)-10-camphorsulfonic acid (CSA)-doped polyaniline in an emeraldine form (σ - 188 S cm⁻¹) at room temperature. The multilayered film, composed of electrically insulating emeraldine base layers and electrically conducting CSA-doped emeraldine salt layers, exhibited 6 times higher ZT at 300 K than that of a bulk film of CAS-doped polyaniline, showing the highest ZT value of 1.1 × 10⁻² at 423 K. Stretching of the CAS-doped polyaniline film also increased the figure-of-merit of doped polyaniline films along the direction of the stretching.     

Synthesis and characterization of conductive polypyrrole grown on the sulfonated surface of polyethylene films

Chemical synthesis of polypyrrole (PPy) was carried out in the presence of FeCl₃ aqueous solution. The grown PPy is fixed on the sulfonated surface of polyethylene (SPE) films, where the sulfonic groups act as counteranions to balance the positive charge of PPy, giving the composite material of PPy–SPE. For reasons of comparison, two types of polyethylene (PE) have been used, low and high densities with different degrees of sulfonation, SD (g/m²), defined as the ratio of weight increase to the area of the two surfaces of the sample. A series of reaction times was used to evaluate the variation of the electrical conductivity, σ (S/cm), of polypyrrole. It was found that σ increases as reaction time increases. To characterize the samples, Fourier transform infrared (FTIR) spectroscopy and conductivity measurements were performed.     

聚吡咯薄膜的电特性

含有不同的链长的w-吡咯烷基二甲基氯硅烷作为粘合剂通过自组装（SAMs）吸附于二氧化硅表面,然后聚吡咯膜化学沉积于该粘合剂修饰的表面。化学沉积的聚吡咯膜的表面形貌用扫描电镜（SEM）及原子力显微镜（AFM）表征。除短链外不同链长的粘合剂对聚吡咯膜的厚度影响不大。聚吡咯膜的电特性用电流-电压表征。结果显示电流与粘合剂的链长无关。电特性表明载流子迁移率为1.4 ´ 10-4 cm2×V-1.s –1。     

The Polymerization and Oxidation of Pyrrole by Halogens in Organic Solvents

Simultaneous chemical polymerization and oxidation of pyrrole have been initiated by a halogenic electron acceptor, bromine or iodine, in various organic solvents. The polypyrrole (PPY)-halogen charge transfer (CT) complexes obtained from polymerization in acetonitrile are of particular interest. Both the PPY-I₂ and PPY-Br₂ CT complexes are granular in nature and have an electrical conductivity in the order of 1 to 10 ohm^?1 cm^?1. Both complexes show remarkable stability in the atmosphere and in the presence of moisture. The PPY-I₂ and PPY-Br₂ CT complexes in the form of thin, coarse films have also been synthesized on a SnO₂ electrode by electrochemical polymerization in acetonitrile. The physicochemical properties of the PPY-I₂ and PPY-Br₂ CT complexes prepared by the chemical methods are characterized by means of UV-visible and IR absorption spectroscopy, thermal and chemical analysis, and electrical conductivity and density measurements.     

Electrochemistry and electrocatalytic activity of polypyrrole/ferrocyanide films on a glassy carbon electrode

Functionalized polypyrrole films were prepared by incorporation of Fe(CN)₆ ³⁻ as doping anion during the electropolymerization of pyrrole at a glassy carbon electrode from aqueous solution. The electrochemical behavior of the Fe(CN)₆ ³⁻/Fe(CN)₆ ⁴⁻ redox couple in polypyrrole was studied by cyclic voltammetry. An obvious surface redox reaction was observed and dependence of this reaction on the solution pH was illustrated. The electrocatalytic ability of polypyrrole film with ferrocyanide incorporated was demonstrated by oxidation of ascorbic acid at the optimized pH of 4 in a glycine buffer. The catalytic effect for mediated oxidation of ascorbic acid was 300 mV and the bimolecular rate constant determined for surface coverage of 4.5 × 10⁻⁸ M cm⁻² using rotating disk electrode voltammetry was 86 M⁻¹ s⁻¹. Furthermore, the catalytic oxidation current was linearly dependent on ascorbic acid concentration in the range 5 × 10⁻⁴–1.6 × 10⁻² M with a correlation coefficient of 0.996. The plot of i _p versus v ^1/2 confirms the diffusion nature of the peak current i _p. Received: 12 April 1999 / Accepted: 25 May 1999     

Polyethylene oxide—polysiloxane branched copolymers and networks

The hydrosilylation of vinyl methyl and divinyl ethers of oligoethylene glycols with polyhydridosiloxanes in the presence of chloroplatinic acid is accompanied by side processes, namely, polymerization of vinyl ethers and homodehydrocondensation of polyhydridosiloxanes. The electrical conductivity of ∼1M solutions of lithium triflate or bis(trifluoromethylsulfonyl) imide in the resulting hydrosilylation products is ∼10⁻⁵ S cm⁻¹.     

Conductive Composite Materials of Polyethylene and Polypyrrole with High Modulus and High Strength

Composite films of polyethylene (PE) and polypyrrole (PPy) were prepared by polymerization of PPy on an ultradrawn polyethylene film with high modulus and high strength in ferric chloride (FeCl₃) aqueous solution. The electrical conductivity of the composite film was found to be related to the polymerization conditions, such as polymerization temperature, polymerization time, the concentration and the oxidation potential of the FeCl₃ solution. Scanning electron microscopy, FTIR and ¹³C NMR spectra were used to elucidate the morphological and structural variations of PPy prepared under different conditions, which lead to the differences in the electrical properties of the resultant composite films. The best electrical conductivity of the composite was about 5.5 S/cm for the film prepared under optimum conditions. The Young's modulus and the tensile strength reached 80 GPa and 3.2 GPa, respectively, which indicated the successful production of a conductive polymer with high strength and high modulus.     

Preparation and electrochemistry of modified polypyrrole films by anodic copolymerization techniques

The anodic copolymerization of pyrrole and N-(ω-ferrocenylalkyl)pyrroles, FcPy-n, at platinum electrodes in an electrolyte consisting of tributylammonium benzenesulfonate in moist acetonitrile is optimized with respect to the absolute and relative concentrations of the monomers and the spacer length of FcPy-n. The copolymer composition is estimated from cyclic voltammograms of the polymer films. Only films with less than 20% FcPy-n content show the typical polypyrrole voltammograms. Free standing copolymer films with a conductivity of ca. 10 S cm⁻¹ can be prepared.     

Highly enhanced thermoelectric performance of WS2 nanosheets upon embedding PEDOT:PSS

Two‐dimensional (2D) WS₂ nanosheets (NSs) as a promising thermoelectric (TE) material have gained great concern recently. The low electrical conductivity significantly limits its further development. Herein, we reported an effective method to enhance the TE performance of WS₂ NSs by combining poly(3,4‐ethylenedioxythiophene):poly(4‐styrenesulfonate) (PEDOT:PSS). The restacked WS₂ NSs thin film with 1T phase structure obtained by a common chemical lithium intercalation show a high Seebeck coefficient of 98 μV K^?1 and a poor electrical conductivity of 12.5 S cm^?1. The introduction of PEDOT:PSS with different contents obviously improve the electrical conductivity of WS₂ NSs thin films. Although a declining Seebeck coefficient was observed, an optimized TE power factor of 45.2 μW m^?1 k^?1 was achieved for WS₂/PEDOT:PSS composite thin film. Moreover, the as‐prepared WS₂/PEDOT:PSS thin film can be easily peeled off and transferred to other substrate leading to a more promising application. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55 , 997–1004     

Physio-chemical influence of high electron-phonon coupling induced by 120 MeV Ag9+ SHI irradiation on exfoliated MoS2 - PVA nanocomposite films for achieving remarkable electrical conductivity for potential application in organic electronics

Swift heavy ion (SHI) irradiation technology is known to enhance the optical, electronic, mechanical, and electrical properties in polymer nanocomposites by the virtue of electron-phonon coupling. In the present work, Molybdenum disulphide (MoS₂), a two-dimensional metal dichalcogenide, has been exfoliated via liquid-phase exfoliation using N-methyl-2- pyrrolidone (NMP) as the solvent that yielded nanosheets of around 2–4 layers as depicted by HR-TEM images. MoS₂ - PVA free-standing films were prepared by wet chemical technique i.e. solution casting method and irradiated by focussed high-energy Ag⁹⁺ ion beam at fluence range of 1E10 - 3E11 ions/cm². As a consequence, the structural modification was observed by X-Ray diffraction studies that showed the shift of (002) plane of MoS₂ while Raman studies indicated the decrease of degree of disorderness at fluence 1E10 ions/cm². SHI irradiation has found to induce a two-order increase in the electrical conductivity yielding a 9.7 E-3 S/cm against that of the pristine films at 2.6E-5 S/cm. The enhanced conductivity is attributed to the induced dispersion and annealing of MoS₂ nanosheets in the PVA matrix due to the interaction of 120 MeV Ag⁹⁺ ion beam irradiation as explained by Thermal spike model.     

Synthesis and electrical conductivity of polymers containing trans-1,2-bis(9-carbazolyl)cyclobutane units

Novel poly-Schiff bases (PSB's) that contain trans-1,2-bis(9-carbazolyl)cyclobutane(DCZB) units were synthesized by the direct polycondensation of trans-1,2-bis(3-formyl-9-carbazolyl)cyclobutane with aromatic diamines in n-amyl alcohol at 160°C. Complexation of these PSB's and of poly(vinyl DCZB) (PVDCZB) with iodine produced cation-radical salts which resulted form the transfer of an electron from DCZB moieties to iodine. All the undoped polymers were insulators having electrical conductivity of the order of 10^?10–10^?12 S cm^?1 depending on the structure of polymers. By doping with iodine, the electrical conductivity increased by several orders of magnitude and reached a value of 10^?3 S cm^?1 in the case of PVDCZB and 10^?5–10^?6 S cm^?1 in the case of PSB's. The electrical conductivity of doped PSB's increased with decreasing diamine length. PVDCZB having the same iodine content per carbazole unit as poly(9-vinyl-carbazole) (PVK) has a greater electrical conductivity than PVK.