Chemical Oxidative Polymerization Of Pyrrole Research Articles

Well-Defined Blackberry-Like Polypyrrole Microspheres via Chemical Oxidative Polymerization in the Presence of Functional Floating Bead as<i> In Situ</i> Dopant

Functional floating bead (F-FB), prepared by anchoring the organic sulfonic acid on the surface of the blackberry-like structural FB, was used as both the inorganic substrate and the in situ dopant for the in situ chemical oxidative polymerization of pyrrole to obtain the plypyrrole/functional floating bead (PPy/F-FB) nanocomposite material. The composites possess high electrical conductivity at room temperature. Thermogravimetric analysis shows that the thermal stability of PPy/F-FB composites was enhanced and these can be attributed to the retardation effect of sulfonic acid-functionalized FB as barriers for the degradation of PPy. The morphology of PPy/FB composites showed the well-defined blackberry-like morphology.

Influence of Single-wall Carbon Nanotubes and Polypyrrole Thin Layer Coating on the Electrical Conductivity of PolyHIPE Foams

Conducting poly(styrene-co-divinylbenzene)/single wall carbon nanotube (SWCNT) polyHIPE (polymerized high internal phase emulsion) composite foams were successfully synthesized via emulsion template polymerization. The effect of various SWCNT loadings, 0–1.4 wt.%, on the electrical conductivity and surface morphology of resulting composite foams was investigated. The incorporation of small amount of SWCNT as conducting nanofiller resulted in formation of a percolative network on the surface of polyHIPE foam. As expected, increasing the weight fraction of SWCNT above the percolation threshold, 0.2 wt.%, increased the conductivity of the nanocomposite foams up to 0.8 wt.%, while further increase had no significant change in the electrical conductivity. Scanning electron micrographs indicated that the incorporation of SWCNT led to the microstructural changes in the typical structure of resulting polyHIPE foam. This morphological change can be attributed to the use of an anionic surfactant as SWCNT dispersing agent in the aqueous phase and to subsequent partial instability of the HIPE. The prepared nanocomposite foams were then covered with an ultrathin layer of polypyrrole (PPy) via chemical oxidative polymerization of pyrrole in the presence of dodecylbenzenesulfonic acid sodium salt (DBSNa) as dopant. The shift of bands in the Fourier transform infrared (FTIR) spectrum of the PPy/SWCNT hybrid foam in comparison with the neat PPy coated foam suggested a specific interaction between the PPy chains and SWCNT that would change the conducting polymer conformation and packed structure. The delocalized π-electrons in SWCNT/PPy bond through noncovalent or π-π interactions resulted in the hybrid polyHIPE nanocomposite foams with enhanced electrical conductivity.

Synthesis and electrochemical performance of well-defined flake-shaped sulfonated graphene/polypyrrole composites via facile in situ doping polymerization

Sulfonated graphene (SG) prepared by anchoring the organic sulfonic acid on the surface of the graphene nanosheets was used as the unique dopant for the in situ chemical oxidative polymerization of pyrrole for the well-defined flake-shaped sulfonated graphene/polypyrrole (SG/PPy) composites. The structures of these composites with the different feeding ratio of SG had been characterized by TEM, SEM, FTIR, Raman and XRD techniques. The SG sheets were homogeneously coated on both surfaces with PPy. Themogravimetric analysis revealed a significantly enhanced thermal stability. The SG/PPy composite S-4 (50wt% SG) with the well-defined flake-shaped morphology exhibited the highest electrical conductivity of 50Scm−1, while the SG/PPy composite S-2 (30wt% SG) possessed the highest specific capacitance (261.0Fg−1) at the charge–discharge current density of 1Ag−1 in 1.0M H2SO4 electrolyte. About 87% of its original specific capacitance could be remained after 1000 cycles. The excellent capacitance behavior also was found in electrochemical impedance spectroscopy. It makes the SG/PPy composite a promising electrode material for high performance supercapacitors.

Polypyrrole/lanthanum strontium manganite oxide nanocomposites: Elaboration and characterization

The synthesis of organic–inorganic hybrid polypyrrole (PPy)–lanthanum strontium manganite oxide La0.8Sr0.2MnO3 (LSMO) nanocomposites via chemical oxidative polymerization of pyrrole in presence of LSMO nanoparticles using ferric chloride as oxidant and sodium p-toluene sulfonate as efficient dopant is investigated. The morphology of polypyrrole and its nanocomposites was examined by scanning electron microscopy which have shown that the presence of LSMO nanoparticles strongly affects the particle size of the nanocomposites. The specific interactions between the conducting polymer and the inorganic nanoparticles is highlighted by FTIR characterizations. Transmission electron microscopy and X-ray diffraction measurements of the nanocomposites confirm a core–shell structure with LSMO coated by polypyrrole macromolecular chains. Electrochemical properties of nanocomposites were investigated by cyclic voltammetry measurements in 2M KOH. In such a media, polypyrrole nanocomposite electrode with 30wt% LSMO nanoparticles has shown specific capacitance of 530Fg−1 which is significantly higher than pristine polypyrrole i.e., 246Fg−1. These charge storage differences between the pristine polypyrrole and polypyrrole/LSMO nanocomposite has been attributed to the morphology of the nanocomposite in which the particle sizes, the specific surface area, and pore size distribution have been modified with the incorporation of nanoparticles in the polypyrrole matrix.

Polypyrrole/silver composites prepared by single-step synthesis

Polypyrrole/silver composites were prepared by single-step chemical oxidative polymerization of pyrrole using silver nitrate as an oxidant in aqueous medium at room temperature. The oxidant-to-monomer mole ratio was varied in these experiments. The time needed for yield to be higher than 70% has been estimated to at least several days. The silver content was 70–80wt.%, the conductivity of composites was of the order of 1000Scm−1. The morphology of composites was demonstrated by scanning electron microscopy and that of individual components by transmission electron microscopy. Silver is present mainly as nanoparticles of 50–100nm size, but also as larger objects. Among polypyrrole nanostructures, nanotubes are the most interesting. The molecular structure of polymer component was characterized by FTIR and Raman spectroscopies, and polypyrrole structure was confirmed. Surface-enhanced Raman scattering at PPy–silver interface was observed. Optical microscopy demonstrated the presence of macroscopic silver plates in the composites and thus illustrated the macroscopic heterogeneity of composites.

Preparation and Properties of Waterborne Cationic Polyurethanes/Polypyrrole Conductive Composites

A series of waterborne cationic polyurethanes dispersions (CWPU) was prepared through prepolymerization method by reacting polyethylene glycol (PEG1000) and isophorone diisocyanate (IPDI) with N-methyl diethanol amine (MDEA) as chain extender. Then FeCl3 was employed as oxidant, therefore CWPU/polypyrrole (CWPU/PPy) conductive composite was prepared by in situ chemical oxidative polymerization of pyrrole (Py) in CWPU dispersions. Effects of molar ratio of FeCl3 to Py, Py concentration on the resistivity of the CWPU/PPy composite films were investigated. The structure, morphology and thermal stability were also characterized by Fourier infrared spectra (FT-IR), light scattering, TEM, and TGA. FT-IR demonstrated the presence of hydrogen-bonding interactions between CWPU and PPy. The average particle size of CWPU/PPy increased from 10.61nm to 30.29nm compared with pure PU, and corresponding size distribution decreased from 0.850 to 0.346. It was also found that CWPU/PPy displayed as spherical morphology, and no aggregation among particles was detected among particles. TGA certified CWPU/PPy was endowed with better thermal stability. In addition, conductivity stability of composites films was also studied. It was found that composite films not only displayed low resistivity but also improved conductivity stability.

Seaweed-like porous carbon from the decomposition of polypyrrole nanowires for application in lithium ion batteries

High yield porous carbon is prepared via the chemical oxidative polymerization of pyrrole and subsequent the decomposition of polypyrrole nanowires with KOH activation. The obtained carbon materials take on a seaweed-like porous morphology. The effects of the KOH mass and activation temperature on the morphology, structure and electrochemical performance of the porous carbon materials are studied in detail. When evaluated for the electrochemical properties in lithium ion batteries as anode materials, one of the unique porous products exhibits an ultra-high reversible capacity of about 1010.2 mA h g−1 at the first cycle and excellent capacity retention in the following cycles.

Effect of Acid Blue BRL on morphology and electrochemical properties of polypyrrole nanomaterials

The spherical or plate-shaped polypyrrole (PPy) nanomaterials were prepared via the chemical oxidative polymerization of pyrrole in the presence of Acid Blue BRL (2-anthracenesulfonic acid, 4-[[4-(acetylmethylamino)phenyl]amino]-1-amino-9, 10-dihydro-9, 10-dioxo, monosodium salt) as both dopant and surfactant. Cyclic voltammetry, electrochemical AC impedance spectroscopy, and galvanostatic charge–discharge tests at various current densities were used to characterize the electrochemical characteristics of the PPy/Acid Blue BRL nanomaterials. A reversible 2e−/ 2H+ redox process was observed for all the PPy/Acid Blue BRL samples. The enhancement of UV–vis characteristic absorption of the π–π* transition of polypyrrole and thermostability of the samples was also observed, due to the doping reaction. The flake-shaped PPy/Acid Blue BRL sample exhibited the highest electrical conductivity of 8.33 S cm− 1 and the highest specific capacitance of 514 F g− 1. The electrochemical data indicated that the formation of the plate-shaped structure of the PPy/Acid Blue BRL nanomaterials improved the electrochemical properties of PPy.

Facile decoration of polypyrrole nanoparticles onto graphene nanosheets for supercapacitors

A facile approach was developed to prepare the graphene nanosheets (GNS) supported polypyrrole (PPy) nanoparticles via the in situ chemical oxidative polymerization of pyrrole onto the surfaces of the GNS modified with sodium dodecyl sulfonate (SDS) as surfactant for GNS and dopant for PPy simultaneously. The morphologies of the graphene nanosheets supported polypyrrole nanoparticles (GNS/PPy nanocomposites) with different feeding ratios were characterized with transition electron microscopy (TEM). It indicated that the PPy nanoparticles had been successfully decorated onto the GNS surfaces. The electrochemical performances of the GNS/PPy nanocomposites were investigated with cyclic voltammetry (CV), constant current charge–discharge and electrochemical impedance spectroscopy (EIS) techniques. The nanocomposite exhibited specific capacitance of 294F g−1 at the charge–discharge current density of 10mAcm−2 in 1.0M NaNO3 electrolyte. It showed that the GNS/PPy nanocomposites might be promising electrode materials for supercapacitors.

Synthesis and characterization of a novel tube-in-tube nanostructured PPy/MnO2/CNTs composite for supercapacitor

Ternary organic–inorganic complex of polypyrrole/manganese dioxide/carbon nanotubes (PPy/MnO2/CNTs) composite was prepared by in situ chemical oxidation polymerization of pyrrole in the host of inorganic matrix of MnO2 and CNTs, using complex of methyl orange (MO)/FeCl3 was used as a reactive self-degraded soft-template. The morphological structures of the composite were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopic (HRTEM), Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), respectively. All the results indicate that the PPy/MnO2/CNTs composite possesses the typical tube-in-tube nanostructures: the inner tubules are CNTs and the outer tubules are template-synthesized PPy. MnO2 nanoparticles may either sandwich the space between the inner and outer tubules or directly latch onto the wall of the PPy tubes. The composite yields a good electrochemical reversibility through 1000 cycles’ cyclic voltammogram (CV) test in the potential range of −0.6 to 0.4V and its specific capacitance was up to 402.7Fg−1 at a current density of 1Ag−1 in galvanostatic charge–discharge experiment.

Low Temperature Hall Effect Investigation of Conducting Polymer-Carbon Nanotubes Composite Network

Polypyrrole (PPy) and polypyrrole-carboxylic functionalized multi wall carbon nanotube composites (PPy/f-MWCNT) were synthesized by in situ chemical oxidative polymerization of pyrrole on the carbon nanotubes (CNTs). The structure of the resulting complex nanotubes was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The effects of f-MWCNT concentration on the electrical properties of the resulting composites were studied at temperatures between 100 K and 300 K. The Hall mobility and Hall coefficient of PPy and PPy/f-MWCNT composite samples with different concentrations of f-MWCNT were measured using the van der Pauw technique. The mobility decreased slightly with increasing temperature, while the conductivity was dominated by the gradually increasing carrier density.

One-step Synthesis of Conducting Polymer–Palladium Nanocomposite Fibers by Aqueous Chemical Oxidative Polymerization

Abstract Aqueous chemical oxidative polymerization of pyrrole using PdCl2 oxidant was conducted in the presence of cetyltrimethylammonium bromide in order to synthesize polypyrrole–palladium (PPy–Pd) nanocomposite in one step. Interestingly, the PPy–Pd nanocomposite was synthesized with fibrous morphology. Transmission electron microscopy studies confirmed that Pd and PPy components formed composite in nanometer dimensions.

Magnetic titania-silica composite–Polypyrrole core–shell spheres and their high sensitivity toward hydrogen peroxide as electrochemical sensor

A novel core–shell sphere with controlled shell thickness was synthesized by in situ chemical oxidative polymerization of pyrrole on FTS (Fe2O3/TiO2/SiO2 composite) surface. The dual porosity of 2–3nm and 40–50nm in FTS core particle provides the hybrids with a high surface area to volume ratio, which enormously facilitates the molecule diffusion process. Furthermore, the porous FTS particle encapsulate Fe2O3 and TiO2 leading to its synergetic interaction with the PPy coating based on FTIR analysis. The unique structure and composition of the hybrid spheres result in new sensing property that is not available from their single counterparts. Cyclic voltammetry results demonstrate that the spheres with appropriate concentration of PPy exhibit enhanced electrocatalytic activity toward the reduction of H2O2 in 0.1M phosphate buffer solution. The sensing performance tests show that the hybrids possess good linear response in wide H2O2 concentration range (10–4000μM) and high sensitivity to H2O2 (0.653AM−1cm−2) at room temperature. The formation mechanism of the spheres was proposed based on the fact that the FTS core was coated firstly by a smooth PPy layer and then PPy nanoparticles. The work reported here provides an alternative concept for preparation of functional materials with new nanostructures and properties.

Electrochemical and XPS study of LiFePO4 cathode nanocomposite with PPy/PEG conductive network

High performance PPy/PEG-LiFePO4 nanocomposites as cathode materials were synthesized by solvothermal method and simple chemical oxidative polymerization of pyrrole (Py) monomer on the surface of LiFePO4 particles. The samples were characterized by scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectrometry (XPS) and charge-discharge tests. PPyPEG hybrid layers decrease particle to particle contact resistance while the impedance measurements confirmed that the coating of PPy-PEG significantly decreases the charge transfer resistance of the electrode material. The initial discharge capacities of this sample at C/5 and 1C are 150 and 128 mAh/g, respectively. The results show that PPy/PEGLiFePO4 composites are more effective than bare LiFePO4 as cathode material.

LiFePO4 Cathode Nanocomposite with PPy/PEG Conductive Network

The polypyrrole-LiFePO4 composites were synthesized by simple chemical oxidative polymerization of pyrrole (Py) monomer directly on the surface of LiFePO4 particles. Properties of resulting polypyrrole-LiFePO4 (PPy-LiFePO4) samples (especially conductivity) are strongly affected by the preparation technique, polymer additives and conditions during synthesis. The polyethylene glycol (PEG) as additive during polymerization was used to increase the PPy-LiFePO4 conductivity. The electrochemical behaviour of samples was examined by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and the chemical stability was evaluated using X-ray photoelectron spectrometry (XPS). It was found that PPy-PEG composite polymer decrease particle to particle contact resistance. Impedance measurements showed that the coating of PPy-PEG significantly decreases the charge transfer resistance of LiFePO4 electrodes. Addition of polyethylene glycol (PEG) during PPy polymerisation leads to enhanced electronic conductivities.

Novel polypyrrole films with excellent crystallinity and good thermal stability

Polypyrrole has drawn a lot of interest due to its high thermal and environmental stability in addition to high electrical conductivity. The present work highlights the enhanced crystallinity of polypyrrole films prepared from the redoped sample solution. Initially hydrochloric acid doped polypyrrole was prepared by chemical oxidative polymerization of pyrrole using ammonium peroxidisulphate as oxidant. The doped polypyrrole was dedoped using ammonia solution and then redoped with camphor sulphonic acid. Films were coated on ultrasonically cleaned glass substrates from the redoped sample solution in meta-cresol. The enhanced crystallinity of the polypyrrole films has been established from X-ray diffraction (XRD) studies. The room temperature electrical conductivity of the redoped polypyrrole film is about 30 times higher than that of the hydrochloric acid doped pellet sample. The results of Raman spectroscopy, Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA) of the samples support the enhancement in crystallinity. Percentage crystallinity of the samples is estimated from XRD and DSC data. The present work is significant, since crystallinity of films is an important parameter for selecting polymers for specific applications.

Effect of oxygen plasma treatment of carbon nanotubes on electromagnetic interference shielding of polypyrrole‐coated carbon nanotubes

AbstractThe polypyrrole (PPy)‐coated multiwalled carbon nanotubes (MWCNTs) were prepared by in situ chemical oxidative polymerization of pyrrole on the surface of MWCNTs for the novel electromagnetic interference (EMI) shielding materials. The oxygen plasma treatment on MWCNTs introduced the hydrophilic functional groups resulting in uniform distribution of MWCNTs and higher interfacial affinity between PPy and MWCNTs. The uniform coating of PPy was formed on MWCNTs due to the effects of oxygen plasma treatment. The thermal stability of PPy‐coated MWCNTs was improved by incorporation of MWCNTs. Absorption was the main mechanism of EMI shielding for the PPy‐coated MWCNTs. The average EMI shielding efficiency of PPy‐coated MWCNTs increased from 21.5 to 28.3 dB by oxygen plasma treatment of MWCNTs. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Polypyrrole–Palladium Nanocomposite Coating of Micrometer-Sized Polymer Particles Toward a Recyclable Catalyst

A range of near-monodisperse, multimicrometer-sized polymer particles has been coated with ultrathin overlayers of polypyrrole-palladium (PPy-Pd) nanocomposite by chemical oxidative polymerization of pyrrole using PdCl(2) as an oxidant in aqueous media. Good control over the targeted PPy-Pd nanocomposite loading is achieved for 5.2 μm diameter polystyrene (PS) particles, and PS particles of up to 84 μm diameter can also be efficiently coated with the PPy-Pd nanocomposite. The seed polymer particles and resulting composite particles were extensively characterized with respect to particle size and size distribution, morphology, surface/bulk chemical compositions, and conductivity. Laser diffraction studies of dilute aqueous suspensions indicate that the polymer particles disperse stably before and after nanocoating with the PPy-Pd nanocomposite. The Fourier transform infrared (FT-IR) spectrum of the PS particles coated with the PPy-Pd nanocomposite overlayer is dominated by the underlying particle, since this is the major component (>96% by mass). Thermogravimetric and elemental analysis indicated that PPy-Pd nanocomposite loadings were below 6 wt %. The conductivity of pressed pellets prepared with the nanocomposite-coated particles increased with a decrease of particle diameter because of higher PPy-Pd nanocomposite loading. "Flattened ball" morphologies were observed by scanning/transmission electron microscopy after extraction of the PS component from the composite particles, which confirmed a PS core and a PPy-Pd nanocomposite shell morphology. X-ray diffraction confirmed the production of elemental Pd and X-ray photoelectron spectroscopy studies indicated the existence of elemental Pd on the surface of the composite particles. Transmission electron microscopy confirmed that nanometer-sized Pd particles were distributed in the shell. Near-monodisperse poly(methyl methacrylate) particles with diameters ranging between 10 and 19 μm have been also successfully coated with PPy-Pd nanocomposite, and stable aqueous dispersions were obtained. The nanocomposite particles functioned as an efficient catalyst for the aerobic oxidative homocoupling reaction of 4-carboxyphenylboronic acid in aqueous media for the formation of carbon-carbon bonds. The composite particles sediment in a short time (<several tens of minutes) by gravity alone and hence recycling of this catalyst is easy.

Effect of oxyfluorination on electromagnetic interference shielding of polypyrrole-coated multi-walled carbon nanotubes

The polypyrrole-coated multi-walled carbon nanotubes (MWCNTs) were prepared by in situ chemical oxidative polymerization of pyrrole on the surface of MWCNTs for the novel electromagnetic interference (EMI) shielding materials. The oxyfluorination treatment on MWCNTs introduced the hydrophilic functional groups resulting in well distribution and higher interfacial affinity between polypyrrole (PPy) and MWCNTs. The PPy phases formed on MWCNTs were observed by SEM. The thickness of PPy on the surface of MWCNTs decreased as increasing the hydrophilic groups on MWCNTs by the oxyfluorination treatment. The PPy-coated MWCNT composites showed the remarkable increases in permittivity, permeability, and EMI shielding efficiency (SE). The EMI SE of PPy-coated MWCNTs increased up about 28.6 dB mainly based on the absorption mechanism.

Polypyrrole nanoparticles with high dispersion stability via chemical oxidative polymerization in presence of an anionic–non-ionic bifunctional polymeric surfactant

Formation of colloidal dispersions is the most attractive and efficient method which can improve the inherent insoluble and intractable properties of polypyrrole. Polyoxyethylene nonylphenyl ether sulfate (NPES), a novel bifunctional polymeric surfactant which has both anionic and non-ionic active groups, was used as both the template and the dopant in the chemical oxidative polymerization of pyrrole in the present work. The size of the NPES doped polypyrrole nanoparticles (PPy/NPES) decreased and their water-dispersion stabilities increased with the increasing of the feeding ratio of NPES. The PPy/NPES nanoparticles possess high electrical conductivity at room temperature and the weak temperature dependence of the conductivity. The conductivity–temperature heating curves are discussed.