Amount Of Polypyrrole Research Articles

The effect of PPY powder on the anticorrosive performance of a duplex cerium/epoxy coating

Polypyrrole powder was chemically synthesized using cerium tartrate as an oxidant. The powder was loaded into an epoxy resin to create a protective coating onto AZ91D Mg alloy. The coatings consisted of an inner cerium-based film and an epoxy layer loaded with different amounts of polypyrrole (0.2–5 wt%) on top. Infrared spectroscopy and Energy Dispersive X-Ray spectroscopy analysis were used to characterize the polymer powder. The anticorrosive properties of the coatings were studied in NaCl containing solution by applying electrochemical measurements such as polarization, electrochemical impedance spectroscopy (EIS), and open circuit potential (OCP). Solution analysis was done to check the electrochemical results obtained. The corrosion resistance was remarkably improved by the addition of the polypyrrole. The best anticorrosive properties were achieved when the epoxy layer was loaded with 1 wt% of PPy. The results show a decrease in corrosion current density from 2.763 × 10-6 to 2.770 × 10-7 mA cm-2 when the polymer was loaded. In addition, the filler reduces the water absorption of the epoxy coating from 9 to 7%. The protective properties were attributed to the barrier behavior of the epoxy film, the corrosion inhibition effect of the PPy, and the self-healing effect of the cerium compounds present in the PPy powder.

The incorporation of polypyrrole (PPy) in CS/PVA composite films to enhance the structural, optical, and the electrical conductivity

AbstractUsing the solution casting method, a blend of polyvinyl alcohol/chitosan (PVA/Cs) blend was prepared with different amounts of polypyrrole (PPy) to enhance the structural and electrical conductivity of the films. The miscibility and interaction between PVA/Cs were confirmed by FT-IR measurements by shifting and disappearing some bands suggesting that the PVA functional group interacted with every other functional group on the Cs side chain. For PVA/Cs/PPy, some band intensities varied, indicating the interaction between PPy and PVA/Cs. XRD showed that the addition of PPy to the blend leads to a noticeable decrease in the intensity of the diffraction peak at 2θ = 20.0° confirming the interactions have occurred between the PVA/Cs mixture and PPy. The UV–visible spectra indicate that increasing the amounts of PPy leads to a dramatic decrease in the energy band gap and an increase in the Urbach energy due to the creation of new energy levels that emerged between conduction and valance bands. After PPy was introduced, the polaron and bipolaron transition peaks at 416, 465, and 560 nm become apparent in the PL spectrum. The dielectric and the electrical properties were reported. The values of ε′ and ε′′ were stronger at low frequencies confirming the possibilities of interface polarization processes. The tan δ behavior diagrams have exhibited one peak trend in all samples shift toward higher frequencies as the temperature and PPy rise. The presence of the peaks was explained based on the electrical conductivity mechanism and dielectric behavior. The Cole–Cole plot displays a half one semicircle shape that explains the absence of contact effects. This semicircle expands as both temperature and PPy increase.

New insights on microwave absorption characteristics of magnetodielectric powders: Effect of matrix chemical nature and loading percentage

Abstract This work presents the preparation of novel microwave absorbing materials (MAMs) based on a combination of two hard ferrites decorated with MWCNTs, namely (SrFe10CoTiO19@MWCNTs and BaFe10CoTiO19@MWCNTs) with or without coating with polypyrrole (PPY). The hard ferrites cores are prepared using the combustion method, while the shell of PPY is deposited by oxidative polymerization method on the ferrite core. X-ray diffractometry (XRD), scanning electron microscopy (SEM), vibrating sample magnetometer (VSM) and vector network analysis (VNA) are performed for microstructural, magnetic and electromagnetic characterization of the MAMs. Also, this work investigates the influence of the chemical nature of hosting matrix and loading percentage on the microwave absorbing characteristics of the MAMs. Results indicate that MAMs exhibit quite different microwave absorbing characteristics depending on the chemical nature of the hosting matrix (polyester vs paraffin). The presence of polar groups in polyester resin has beneficial effects on the microwave absorbing characteristics by enhancing the minimum reflection loss (RL). The frequency of the minimum RL is also blue-shifted by 0.5 GHz when passing from paraffin to polyester hosting matrix. Also, coating the ferritic core with an appropriate amount of polypyrrole as a dielectric shell reduces the loading percentage necessary to obtain promising RL characteristics.

Photopolymerization of pyrrole/methacrylate mixtures using α-cleavage type photoinitiators in combination with iodonium salt

Hybrid systems formulated with pyrrole and methacrylate monomers were photopolymerized with both UV (λ=365nm) and visible (λ=470nm) light. It is known that conducting polymers produced by electrochemical or chemical synthesis are intractable solids or powders which display poor mechanical properties and low processability. An advantage of the photopolymerization process is that it allows processability and mechanical properties of final polymers to be optimized by incorporating flexibilizers and different additives into photopolymerizable formulations. Mixtures pyrrole/methacrylate were photoactivated with the iodonium salt p-(octyloxyphenyl)phenyliodonium hexafluoroantimonate (Ph2ISbF6), in combination with 2,2-dimethoxy-2-phenylacetophenone (DMPA), 2-methoxy-2-phenylacetophenone (BZME) or the pair camphorquinone (CQ)/ethyl-4-dimethylamino benzoate (EDMAB). The Ph2ISbF6 in combination with DMPA or BZME was an efficient photoinitiator system under irradiation at 365nm. Conversely, in mixtures photoactivated with Ph2ISbF6/CQ/EDMAB the polymerization of both pyrrole and methacrylate was comparatively slow. Microscopy studies revealed the absence of phase separation indicating that the mixtures pyrrole/methacrylate resulted in the formation of an interpenetrating polymer network. The electrical conductivity of the hybrid polymers increased markedly with the amount of polypyrrole as a result of the formation of a conducting polymer network in the insulating BisEMA matrix.

Synthesis and characterization of polypyrrole/H-Beta zeolite nanocomposites

Transmission electron micrographs of (a) H-Beta-25, (b), (c) and (d) 1 ml PPy/H-Beta-25 composite.

Enhanced visible light photocatalytic activity of Bi2WO6 via modification with polypyrrole

Enhanced visible light photocatalytic activity of Bi2WO6 photocatalyst modified with different amounts of polypyrrole (PPy) was synthesized by ‘in situ’ deposition oxidative polymerization of pyrrole. The as-prepared PPy/Bi2WO6 composites were characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR) spectra, X-ray photoelectron spectroscopy (XPS) and UV–vis diffuse absorption spectra. The photocatalytic activities of the PPy/Bi2WO6 samples were determined by photocatalytic degradation of rhodamine-B (RhB) and methylene blue (MB) in aqueous solution under visible light irradiation. The results indicated that the existence of PPy did not affect the crystal structure and the morphology of Bi2WO6 photocatalyst, but showed great influences on the photocatalytic activity of Bi2WO6. Besides, an optimal content of PPy on the surface of Bi2WO6 photocatalyst with the highest photocatalytic ability was discovered, and the obtained PPy/Bi2WO6 photocatalysts showed high stability and did not photocorrode during the photocatalytic process. The possible mechanism of enhanced photocatalytic activities of PPy/Bi2WO6 samples was also discussed in this work.

Photoelectrochemical properties of polypyrrole/TiO2 nanotube arrays nanocomposite under visible light

In this study, different amount of polypyrrole (PPy) were electropolymerized on highly ordered TiO2 nanotube arrays (TiO2NTs) anodized by Ti foil in aqueous solution containing fluoride. In order to improve the conductivity of PPy, an anionic surfactant sodium dodecyl benzene sulfonate (SDBS) was used as doping during electropolymerization. The PPy modified TiO2NTs was confirmed by scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FTIR) and UV–vis spectroscopy (UV–vis). The results indicated that there might exist a strong interaction between TiO2NTs and PPy. Photoelectrochemical response showed that PPy/TiO2NTs electropolymerized for 30s presented the maximum IPCE 1.81% under 550nm visible light. The results were ascribed to the presence of narrow band gap p-type conducting polymer semiconductor PPy enhancing visible-light absorption and decreasing the recombination of photo electron–hole result in enhanced photocurrent. These results have implications for the use of PPy/TiO2NTs as a photoswitch or solar cell.

Synthesis, characterization, and properties of conducting polypyrrole/Na-montmorillonite nanocomposites

Polypyrrole/Na-montmorillonite nanocomposites were prepared by oxidative polymerization of pyrrole in aqueous medium using ammonium peroxydisulfate as the oxidant. The synthesized nanocomposites were confirmed by a series of characterization techniques including Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and thermal analysis. X-ray diffraction and transmission electron microscopy images showed that the polypyrrole was intercalated into the clay layers. The thermogravimetric analysis and differential thermal analysis revealed the improved thermal stability of nanocomposites with respect to pure polypyrrole due to modification of the incorporated Na-montmorillonite. Furthermore; adsorptive properties, the moisture retains, and water uptake values of nanocomposites were investigated. Conductivity behaviour of nanocomposites was also studied. The nanocomposites exhibit the room temperature conductivities varied from 1.2 × 10−8 S cm−1 to 8.7 × 10−8 S cm−1 range, depending on the amount of polypyrrole.

Electrochemical synthesis and characterization of poly(pyrrole‐co‐ε‐caprolactone) conducting copolymer

AbstractThe direct electrochemical copolymerization of pyrrole (Py) and ε‐caprolactone at various monomer ratios was carried out by potentiostatic methods in nitromethane. Characterizations of the novel copolymer were based on scanning electron microscopy, differential scanning calorimetry, thermal gravimetrical analysis, cyclic voltammetry, electrochemical impedance spectroscopy, Fourier transform infrared spectra, and elemental analysis studies. The results showed that the electrochemical oxidation of Py and ε‐caprolactone comonomers generated true copolymers rather than blends of the two homopolymers. The electrical conductivity of the copolymers increased with the amount of polypyrrole in the copolymer between the value of 8.2 S/cm and 0.6 S/cm. A probable mechanism of copolymerization was proposed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Electrochemical synthesis and characterization of poly(pyrrole-co-tetrahydrofuran) conducting copolymer

The direct electrochemical copolymerization of pyrrole and tetrahydrofuran in various monomer ratios was carried out by potentiostatic methods in nitromethane solution. The copolymer has been characterized using FT-IR, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetrical analysis (TGA), cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and elemental analysis. The results showed that the electrochemical oxidation of pyrrole and tetrahydrofuran comonomers generated true copolymers rather than blends of the two homopolymers. The copolymer showed a better flexibility than pure polypyrrole. The electrical conductivity of the copolymers increases with the amount of polypyrrole in the copolymer between the value of 1.69 S/cm and 0.71 S/cm.

Investigation of Layered Structures of Synthetic Smectite/Polypyrrole Composite Powders Prepared by Vapor Phase Polymerization

Composite powders of Fe3+-exchanged synthetic smectite and polypyrrole were prepared by using pyrrole vapor, and their layered structures were investigated by Fourier transform-infrared spectrophotometer (FT-IR), X-ray diffractometer (XRD) and Thermogravimeter-Differential thermal analyzer (TG-DTA). The results showed that chemical oxidative polymerization of the pyrrole occurred in the interlayer spaces between silicate layers; the increment of the polypyrrole depended on vapor phase reaction time. The amount of polypyrrole and interplanar spacing of the composite powders increased gradually, and it was concluded that two layers of polypyrrole formed on both sides of Fe3+ in each space. The rate determining step of the reaction was the absorption and the diffusion of the pyrrole into the interlayer spaces. By TG-DTA, it was found that the thermal stability of the polypyrrole in the composite powders improved, for the polypyrrole being strongly restrained from burning and pyrolyzing in nanoscale spaces between silicate layers. A part of the polypyrrole was carbonized when the composite powders was heated up in N2 with gradually rising temperature. The laminated carbon influenced the structural change of silicate layers. An increment of carbonization suggested that the laminated polypyrrole changed into a precursor for carbon under suitable conditions.

Synthesis and characterization of polypyrrole-graft-poly(ε-caprolactone) copolymers: new electrically conductive nanocomposites

A series of polypyrrole-graft-poly(ε-caprolactone) (PPy-g-PCL) copolymers have been synthesized via oxidative copolymerization of pyrrole and pyrrole-end functional macromonomers. Copolymerizations were carried out in tetrahydrofuran at 0 °C using FeCl 3 as the oxidizing and doping agent. Poly(ε-caprolactone) rich copolymers (>85 wt.%) were partly soluble in common organic solvents, whereas polypyrrole-rich copolymers were completely insoluble. The composition of the PPy-g-PCL copolymers was determined by Fourier transform infra-red (FTIR) spectroscopy and thermal gravimetrical analysis (TGA). By controlling the monomer feed and molecular weight of the macromonomer, graft copolymers across a broad composition range were obtained. Both differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) show that the PPy-g-PCL copolymers phase separate into PPy and PCL rich domains. The electrical conductivity of the nanocomposites increases with the amount of polypyrrole in the copolymer between the value of pure PCL (10 −12 S/cm) and that of polypyrrole (10 S/cm). Atomic force microscopy (AFM) confirmed the presence of nanophases (15–40 nm) and hence, the preparation of new nanomaterials.

Charge-discharge properties of composites of polypyrrole and vanadium oxide powder

Composite of polypyrrole and crystalline V2O5 powder was prepared by chemical oxidation of pyrrole with use of V2O5 powder itself as an oxidizing agent. The V2O5 content was changed from 0 to 94 wt% by changing the amount of V2O5 dispersed in the preparation bath. The pellet electrodes could be prepared by pressing the composite powder alone even if amount of polypyrrole in the composite was only 6 wt%. The resulting pellet electrode exhibited good charge-discharge performance as a positive electrode of Li rechargeable battery in an electrolyte solution as well as in a quasi-solid cell fabricated by using a gel electrolyte sheet of poly(methyl methacrylate).

Formation of transparent conducting films based on core-shell latices: Influence of the polypyrrole shell thickness

Transparent conducting latex films have been prepared from core-shell latices. The latex particles have a poly(butyl methacrylate) (PBMA) core of about 700 nm and a very thin polypyrrole (PPy) shell. We have studied the film formation of latices with 1, 2, and 4 wt % PPy and compared this with the film formation of the pure PBMA latex. The film formation process was studied by transparency measurements, atomic force microscopy surface flattening, and transmission electron microscopy on ultrathin sections of films after various annealing times at 120°C. It is demonstrated that highly transparent (>90%) and antistatic films can be produced using these latices. The presence of a polypyrrole shell around the PBMA latex particle seriously hinders the deformation of the particles. The amount of polypyrrole, and thus the shell thickness, is the determining factor for the speed of film formation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 900–909, 2001

An alternating current impedance study of polypyrrole/poly(vinyl chloride) composites

A.c. impedance studies of poly(vinyl chloride)–polypyrrole composites deposited on platinum electrodes and in contact with an acetonitrile solution containing 0.1 mol dm–3 tetrabutylammonium tetrafluoroborate (as supporting electrolyte) are described. Data are presented for the frequency range 0.1 Hz–65 kHz, and in this way the conductivity of the composite is found. The latter is related to the potential applied via the platinum electrode to the composite, and to the amount of polypyrrole incorporated within the composite. In-situ electrochemical e.s.r. measurements on the composite are also described, and these, together with the a.c. data, indicate the electrical properties and behaviour of the composite material to be similar to polypyrrole itself.

Anomalous voltage-controlled negative resistance in Pt-insulator-conductive polymer-Au junctions

Anomalous electrical properties have been found for platinum-insulator-polypyrrole-gold junction cells where the insulator layer is doped with a small amount of polypyrrole. The electroformed samples exhibit voltage-controlled negative resistance (VCNR) with an exceptionally low peak voltage of 1.75 V. Linear sweeps of dc voltages between 0 and 3 V result in a switching phenomenon in which a low resistance on state (VCNR state) and a high resistance off state alternately appear. These anomalies are tentatively assumed as being due to reversible charge storage at the polypyrrole sites in the insulator layer.