Effects of solvents on thermoelectric performance of PANi/PEDOT/PSS composite films

Organic thermoelectric materials based on conducting polymers, especially for polyaniline (PANi) and poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT/PSS), have attracted great concern due to their tunable electron transport properties by controlling doping level. Here, the solvent effects of deionized H₂O and NH₃·H₂O were investigated on the electrical conductivity and Seebeck coefficient of PANi/PEDOT/PSS composite films. The introduction of PEDOT/PSS can not only effectively improve the quality of pure PANi film, but also enhance the electrical conductivity of PANi film. The different volumes of deionized H₂O as dilution have a great influence on the electrical conductivity of PANi/PEDOT/PSS composite thin film with a maximum electrical conductivity value of 63.5 S cm^?1, which is much higher than pure PANi and pristine PEDOT/PSS. The introduction of NH₃·H₂O shows a positive effect on Seebeck coefficient with a large decline on electrical conductivity of PANi/PEDOT/PSS. The Raman spectroscopy, scanning electron microscopy (SEM), and UV-vis spectroscopy were used to obtain the morphology and structure information of PANi/PEDOT/PSS.     

Electrochemical synthesis of nanostructured polyaniline: Heat treatment and synergistic effect of simultaneous dual doping

Different nanostructured polyaniline (PAni) has been synthesized via facile template‐free electrochemical synthesis approach in aqueous medium. Instead of conventionally used aniline, aniline sulphate was used in electrochemical polymerization. The synthesis process involves simultaneous doping with combination of inorganic and organic acid, i.e., sulfuric acid (H₂SO₄) and p‐toluenesulfonic acid (PTSA) at different ratios keeping total dopant concentration constant. Synergistic increase in conductivity is observed and the best conductivity is achieved at 3:1 ratio of [H₂SO₄]:[PTSA]. Different nanostructures of PAni are revealed through morphological analysis consisting of nanosphere, nanorod, and clustered particles among which finer nanorods show the best electrical conductivity. Upon controlled heat treatment followed by further cooling, resistivity increases, but after one day it decreases again and in the optimized dual doped PAni, it approaches approximately the same value of initial resistance. Lattice strain and benzenoid to quinonoid ratio increases with heat treatment. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and electrical properties of the (PVA)0.7(KI)0.3·xH2SO4 (0 ≤ x ≤ 5) polymer electrolytes and their performance in a primary Zn/MnO2 battery

Solid acid polymer electrolytes (SAPE) were synthesised using polyvinyl alcohol, potassium iodide and sulphuric acid in different molar ratios by solution cast technique. The temperature dependent nature of electrical conductivity and the impedance of the polymer electrolytes were determined along with the associated activation energy. The electrical conductivity at room temperature was found to be strongly depended on the amorphous nature of the polymers and H₂SO₄ concentration. The ac (100 Hz to 10 MHz) and dc conductivities of the polymer electrolytes with different H₂SO₄ concentrations were analyzed. A maximum dc conductivity of 1.05 × 10⁻³ S cm⁻¹ has been achieved at ambient temperature for electrolytes containing 5 M H₂SO₄. The frequency and temperature dependent dielectric and electrical modulus properties of the SAPE were studied. The charge transport in the present polymer electrolyte was obtained using Wagner's polarization technique, which demonstrated the charge transport to be mainly due to ions. Using these solid acid polymer electrolytes novel Zn/SAPE/MnO₂ solid state batteries were fabricated and their discharge capacity was calculated. An open circuit voltage of 1.758 V was obtained for 5 M H₂SO₄ based Zn/SAPE/MnO₂ battery.     

Processing and properties of new heteroaromatic Schiff-base poly(sulfone-ester)s and their blends

A new interesting class of linear Schiff-base poly(sulfone-ester)s has been synthesized by polycondensation of (E)-1-(4,4′-(4-hydroxy-3-chlorobenzylidene)thiocarbamoylaminophenyl-sulfonylphenyl)-3-(4-hydroxy-3-chlorobenzylidene)thiourea with 2,6-pyridinedicarbonyl chloride/thiophene-2,5-dicarbonyl dichloride. The enhancement of physical properties (thermal stability, glass transition temperature, mechanical strength, molar mass, electrical conductivity, etc.) of polymeric materials while maintaining their processability was the foremost aspiration of this research work. The pyridine or thiophene-based heteroaromatic poly(sulfone-ester)s (PSEs) showed ample solubility in amide solvents and good yield. PSEs possessed high inherent viscosity of 1.79–1.93 dL/g and molar mass 125 × 10³–145 × 10³ g mol^?1. The polymers were thermally stable with 10 % weight loss in the range 538–547 °C and glass transition temperature between 293 and 296 °C. Further aim was to obtain novel miscible nano-blends exhibiting good electrical conductivity and heat stability. For this purpose, PAN doped with dodecylbenzenesulfonic acid (PAN/DBSA) was prepared by in situ doping polymerization, and then blended in solution/melt with PSEs. The resulting high performance materials potentially combined the fine thermal properties and processability of poly(sulfone-ester)s with electrical characteristics of polyaniline. FESEM of melt-blended PSEs/PAN/DBSA showed nano-level homogeneity of the microstructure liable for better electrical conductivity (2.7–3.2 S cm^?1). The azomethine and pyridine moieties introduced in the backbone render these polymers thermally and mechanically stable as well as electrically conducting. The miscible blends, exhibited good heat stability (T ₁₀ 520–527 °C, T _g 281–285 °C) and mechanical strength (55.20–57.18 MPa) compared with reported azomethine/polyaniline-based structures. New processable and high-performance engineering plastics, attractive for aerospace applications, can be fabricated using novel blends.     

The Conductivity of Poly(o-anisidine), Poly(o-toluidine) and Their Copolymer with Various Inorganic Dopants in the Presence of Electrolyte

ABSTRACT

An attempt has been made to prepare poly(o-anisidine) (POA), poly(o-toluidine) (POT) and copolymer poly(o-anisidine)-co-poly(o-toluidine) (POA-co-POT) thin films dopped by several inorganic salts (sulphates and chlorides) with varying size of cations using aqueous solution of H₂SO₄ as electrolyte. The effect of dopant in the presence of electrolyte is rarely studied in the field of conducting polymers. Various inorganic salts as dopants, namely, K₂SO₄, Na₂SO₄, Li₂SO₄, MgSO₄, KCl, NaCl, LiCl, and MgCl₂ are used at room temperature. The films were electropolymerized in solution containing 0.1 M monomer(s), 1 M H₂SO₄ as electrolyte and 1 M inorganic salt, by applying sequential linear potential scan rate 50 mV/sbetween ? 0.2 to 1.0 V versus Ag/AgCl electrode. The electro-synthesized films were characterized by cyclic voltammetry, UV-visible spectroscopy, and conductivity measurements. It was observed that the UV-visible peaks usually appearing at about 802–826 nm with a shoulder at 410–426 nm shows a shift in presence of doping salt for emeraldine salt (ES) phase of POA, POT, POA-co-POT. In overall study, a significant increase in conductivity is observed for all mentioned dopants and among these K₂SO₄ is found to be the best in sulphate category and KCl in chloride category. The formation of copolymer has been confirmed by differential scanning calorimetry.     

Polyaniline Salts and Complexes as Catalyst in Bisindole Synthesis

Polyaniline salts are prepared by doping of polyaniline base with different Bronsted acids (H₂SO₄, HNO₃ and H₃PO₄), organic acid — p-toluene sulfonic acid (PTSA) and Iodine (I₂). Polyaniline complexes are also prepared using Lewis acids (BF₃, AlCl₃ and SnCl₂). Polyaniline salts and polyaniline complexes are characterized by physical, electrical and spectral methods. Polyaniline salts and polyaniline complexes are used as catalyst for the first time in bisindole synthesis. Bisindole (3,3′-bis(indolyl)phenylmethane) is obtained in excellent yields with simple and more environmental benign procedure. The use of polyaniline catalysts are feasible because of their easy preparation, easy handling, stability, easy recovery, reusability, good activity and eco-friendly.     

Preparation,structural, and electrical studies of polyaniline/ZnFe2O4 nanocomposites

Polyaniline/ZnFe₂O₄ nanocomposites were synthesized by a simple and inexpensive one‐step in situ polymerization method in the presence of ZnFe₂O₄ nanoparticles. The structural, morphological, and electrical properties of the samples were characterized by wide angle X‐ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). WAXD and SEM revealed the formation of polyaniline/ZnFe₂O₄ nanocomposites. Infrared spectroscopy indicated that there was some interaction between the ZnFe₂O₄ nanoparticles and polyaniline. The dc electrical conductivity measurements were carried in the temperature range of 80 to 300 K. With increase in the doping concentration of ZnFe₂O₄, the conductivity of the nanocomposites found to be decreasing from 5.15 to 0.92 Scm⁻¹ and the temperature dependent resistivity follows ln ρ(T) ∼ T^−1/2 behavior. The nanocomposites (80 wt % of ZnFe₂O₄) show a more negative magnetoresistance compared with that of pure polyaniline (PANI). These results suggest that the interaction between the polymer matrix PANI and zinc nanoparticles take place in these nanocomposites. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Simultaneous Oxidation and Doping of Aniline to Polyaniline by Oxidative Template: Electrochemical Performance in Supercapacitor

Polyaniline salts containing sulfuric acid and cetyltrimethylammonium sulfate dopants were prepared by aqueous (PANI-Aq), emulsion (PANI-Em), and interfacial (PANI-In) polymerization pathways using cetyltrimethylammonium peroxodisulfate as an oxidative template. Formation of polyaniline was confirmed from infrared and X-ray diffraction spectral results. Value of conductivity (15 S cm^?1) of the polyaniline salt prepared by emulsion polymerization pathway was higher with that of the conventional polyaniline salt. PANI-Aq, PANI-Em, and PANI-In showed layered, flower petals, and nanorod and flower petals morphologies, respectively. These polyaniline salts were used as electrode in supercapacitor. Specific capacitance of PANI-Em, PANI-Aq, and PANI-In were 520, 484, and 474 F g^?1, which were higher than the conventional PANI-H₂SO₄ salt (390). Energy density was 26, 24.2, and 23.6 Wh kg^?1, respectively at a power density of 120 W kg^?1. After 3000 charge-discharge cycles, retention in the specific capacitance values of polyaniline salts was 86% (PANI-Em), 85.4% (PANI-Aq) and 76.1% (PANI-In).     

Ionic Liquid-assisted Synthesis of Polyaniline/Gold Nanocomposite and Its Biocatalytic Application

In this report, a novel chemical synthesis of polyaniline/gold nanocomposite is explored using ionic liquid (IL) 1-Butyl-3-methylimidazolium hexafluorophosphate. The direct chemical synthesis of polyaniline/gold nanocomposite was initiated via the spontaneous oxidation of aniline by AuCl₄ ⁻ in IL. A nearly uniform dispersion of polyaniline/Au particles with a diameter of 450 ± 80 nm was produced by this method, which indicates that this method is more suitable for controlling particle dimensions. It was also found that the electrical conductivity of the polyaniline/gold nanocomposite was more than 100 times higher than that of the pure polyaniline nanoparticles. The polyaniline/gold nanocomposite displays superior function in the biocatalytic activation of microperoxidase-11 because of the high surface area of the assembly and the enhanced charge transport properties of the composite material. We also report the possible application of polyaniline/gold nanocomposite as a H₂O₂ biosensor.     

Synthesis and properties of oxalic acid-doped polyaniline

Conductive polyaniline was synthesized in aqueous 1.0M oxalic acid containing 0.1 M aniline by electrochemical and chemical oxidation and characterized by conductivity, solubility, ultraviolet and infrared spectroscopy, and cyclic voltammetry. The solubility experiments showed that the solubility of oxalic acid-doped polyaniline in dimethylsulfoxide and dimethylformaide increased to a certain extent. The soluble part of the polyaniline was free from impurities such as quinones. Cyclic voltammetric studies in oxalic acid medium revealed that aniline exhibited a similar behaviour to that in H₂SO₄ and the polymerization rate was much slower than that in H₂SO₄.     

Characterization of polypyrrole films incorporating various anions

The conductivity of polypyrrole films has been enhanced by electrochemical post-deposition doping with various anions. The change of conductivity was found to depend on the type and concentration of the anion. Results for the polypyrrole films doped with anions of H₂SO₄, (C₂H₅)₄N(O₃SC₆H₄CH₃), KI, CH₃C₆H₄SO₃H · H₂O (p-toluene sulphonic acid monohydrate), AlCl₃, KBrO₃ and HNO₃ showed that in the case of H₂SO₄, (C₂H₅)₄ N(O₃SC₆H₄CH₃) and CH₃C₆ H₄SO₃ H · H₂O the conductivity can be enhanced by up to a factor of two, from a value of 67 S cm^–1 up to 165, 102 and 95 S cm^–1, respectively. Doping with I^– had a negligible effect on the conductivity which was about 71 S cm^–1, while in the case of AlCl₃, KBrO₃ and HNO₃ the conductivity of the polypyrrole decreased significantly for certain anion concentrations.     

Polyaniline synthesis using hydrofluoric acid as doping agent: Comparative evaluation with polyaniline doped with sulfuric acid

This work focuses on the comparison between the morphological, chemical, and electrical properties of polyaniline doped with fluoridric and polyaniline, and doped with sulfuric acid. The FT‐IR, XRD, and SEM/EDS results indicate that the use of hydrofluoric acid as doping agent does not provide meaningful changes in the crystalline and morphological structure of polyaniline. Although, the inclusion of F^? type counter‐ions from the doping process with HF provide more compact, denser, and with higher electrical conductivity polymeric matrices. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013     

A H2SO4 Loaded Polybenzimidazole (PBI) Membrane for High Temperature PEMFC

Sulfuric acid loaded polybenzimidazole (PBI) membranes were prepared with loading levels up to 10.58 (acid molecule per repeat unit of PBI) and characterized with Fourier transform infrared spectroscopy. Ionic conductivity of the PBI–H₂SO₄ membrane was found greater than that of the PBI–H₃PO₄ membrane. Through plane conductivity of a PBI–H₂SO₄ membrane with loading level 9.65 was >0.2 S cm^–1 at 150 °C. However, the conductivity of PBI–H₂SO₄ membrane increased greatly with increasing relative humidity. Membrane electrode assemblies using PBI–H₂SO₄ membrane exhibited better power density performances with pre‐humidified H₂ and air than that with none‐humidified gases. Polymer electrolyte membrane fuel cells with PBI–H₂SO₄ membrane in a single cell fixture demonstrated a peak power density >0.35 W cm^–2 with H₂ and air.     

Design,synthesis and characterization of novel electroactive polyamide with amine‐capped aniline pentamer in the main chain via oxidative coupling polymerization

By oxidative coupling polymerization of the macromonomer of oligoaniline and p‐phenylenediamine we have prepared a novel electroactive polyamide, exhibiting well‐defined molecular structure, interesting spectroscopic and electrochemical properties. The well‐defined molecular structure of the electroactive polyamide was confirmed by FTIR, NMR spectroscopy, elemental analysis and X‐ray powder diffraction (XRD) and the resulting polyamide exhibit an enhanced solubility in most of the organic solvents as compared with polyaniline. The UV–Vis spectra were used to monitor the chemical oxidation process of the reduced polyamide. Electrochemical activity of the polyamide was tested in 1.0M H₂SO₄ aqueous solution and it shows three redox peaks, which is different from the polyaniline. Moreover, the thermal properties of the polyamide were evaluated by thermogravimetric analysis (TGA) and it shows moderate thermal resistance in the N₂ atmosphere. Its electrical conductivity is about 1.04 × 10^?4 S cm^?1 at room temperature upon preliminarily protonic‐doped experiment. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1603–1608, 2007     

Electrical properties of polyaniline films formed in acid with and without Cs+ ions in the electrolyte

The effect of Cs⁺ ions added to the electrolyte for polyaniline films electrosynthesized in 0.1 m aniline/0.5m H₂SO₄ was investigated. Some properties of PANI films, such as the capacitance, the ohmic resistance and the charge-transfer resistance were obtained using electrochemical impedance spectroscopy. It was found that Cs⁺ ions used during PANI synthesis change its morphology, with a consequent increase in capacitance and conductivity, and a decrease in charge-transfer resistance.     

Improving the electrochemical properties of polyaniline by co-doping with titanium ions and protonic acid

Polyaniline co-doped with titanium ions and protonic acid was synthesized in aqueous H₂SO₄ solution containing Ti(SO₄)₂ (pH 2), and was characterized via Fourier-transform infrared spectra, UV–vis spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy and cyclic voltammetry. Its conductivity was 2.8 S cm⁻¹ at room temperature (25 °C), which is the same order of magnitude as polyaniline doped with protonic acid (5 S cm⁻¹). Compared with polyaniline doped with protonic acid, it showed a better redox reversibility and cycling stability in aqueous pH 4.0 media, even in an acetate electrolyte (pH 4.0). It could be a promising material for several applications due the increase of the operating pH window of polyaniline in an aqueous environment.     

Preparation of a HDPE/Carbon Nanotube Composite

This experiment adopted mixed acid (H₂SO₄:HNO₃ = 3:1) to purify multi-walled carbon nanotubes, and used a silane coupling agent n-octyltriethoxysilane (OTES) to modify carbon nanotubes, respectively. Then we mixed OTES-modified carbon nanotubes (CNTs) with high-density polyethylene (HDPE) resin to make a composite. TGA analysis results revealed that as the CNTs'content increased, the Td₁₀ tended to rise. The amount of composite residual at 500°C also increased, as well as the composite electrical conductivity. When a concentration of 5% OTES was used to modify the CNT, the resultant composite exhibited better electrical conductivity.     

Polyaniline/polyimide blends as gas sensors and electrical conductivity response to CO–N2 mixtures

The effects of dopant type, doping level, polyimide (PI) content and temperature on electrical conductivity response of polyaniline (PANI) and polyaniline/polyimide (PANI/PI) blends to CO–N₂ gas mixtures were systematically investigated. At the same doping level, HNO₃‐doped PANI has a greater electrical conductivity response and sensitivity towards CO than that of camphor sulfonic acid (CSA)‐doped PANI because the former has a more ordered structure. The interaction mechanism between CO and PANI is proposed to occur at the attack site, ? N?H? or the amine nitrogen where CO withdraws an electron. Addition of PI causes a small change in electrical conductivity under atmospheric conditions when PI content is below the percolation threshold value of 55 wt%. Addition of PI reduces brittleness and improves electrical conductivity sensitivity towards CO; the effect is more pronounced at higher temperatures. Copyright © 2005 Society of Chemical Industry     

Role of dual dopants in highly ordered crystalline polyaniline nanospheres: Electrode materials in supercapacitors

Aniline is oxidized by ammonium persulfate oxidant with a weak organic acid, 1,3‐(6,7)‐napthalene trisulfonic acid (NTSA), via an aqueous polymerization pathway to polyaniline (PANI) salt. The effects of the sodium lauryl sulfate surfactant, mineral acid [sulfuric acid (H₂SO₄)], and a combination of surfactant with mineral acid in the aniline polymerization reaction are also carried. These salts were designated as PANI–NTSA–dodecyl hydrogen sulfate (DHS), PANI–NTSA–H₂SO₄, and PANI–NTSA–DHS–H₂SO₄, respectively. Interestingly, PANI–NTSA–DHS showed a highly ordered crystalline sample with a nanosphere morphology. These PANIs were used as electrode materials in supercapacitor applications. Among the four salts, the PANI–NTSA–DHS–H₂SO₄ material showed higher values of specific capacitance (520 F/g), energy (26 W h/kg), and power densities (200 W/kg) at 0.3 A/g. Moreover, 77% of the original capacitance was retained after 2000 galvanostatic charge–discharge cycles with a Coulombic efficiency of 98–100%. PANI–NTSA–DHS–H₂SO₄ was obtained in excellent yield with an excellent conductivity (6.8 S/cm) and a thermal stability up to 235°C. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42510.     

3D Electrodes from aluminium foams prepared by replication process

Aluminium foams with pores displaying both regular size and distribution have been prepared by replication methods. Their volumetric density and electrical conductivity were 0.65 g cm^?3 and 2.44 MS m^?1, respectively. This method represents a simple way to produce 3D metal macroporous electrodes. In addition, the aluminium foam has been employed as support to produce 3D platinum electrodes (Pt/Al foam) by electrodeposition. The conditions for platinum electrodeposition have been established, and the electrodes were characterized by scanning electron microscopy and cyclic voltammetry. The electrocatalytic behaviour of the Pt/Al foam electrodes to methanol oxidation has been tested in 1 M CH₃OH + 0.5 M H₂SO₄ solutions.