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In this study, an atmospheric‐pressure nanosecond impulse discharge initiated above the pyrrole microemulsion surface is applied to polymerize pyrrole and obtain a polypyrrole film. The films obtained under different number of plasma discharge times and duration of argon gas input time are investigated using a field emission scanning electron microscope. Results show that the roughness and thickness of the polypyrrole film can be tuned by controlling discharge times and the gas feed time. Four‐point sheet resistance measurements of the films reflect that those with a smoother and more complete surface have better electrical conductivity. The films are identified as polypyrrole by Fourier‐transform infrared spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectrometry. Also, N2 is a critical factor in polymerizing polypyrrole and the gas–liquid plasma polymerization mechanism, which has three steps, is discussed. [ABSTRACT FROM AUTHOR]

The three polypyrrole (PPy) films with different mixture ratios, namely PPy1, PPy2, and PPy3, were synthesized by chemical oxidation with pyrrole and ferric chloride (FeCl3). The roughened plastic optical fiber (POF) taper assembled PPy films (POF-PPy1, POF-PPy2, and POF-PPy3) were facilely prepared and bent U shape structure for testing ethanol gas at room temperature. The morphologies of the PPy films and the roughened POF taper were studied using electron microscopy. The effect of the three PPy films on the gas response was investigated and the results showed that the POF-PPy2 exhibited a high sensitivity of 5.08 × 10−5 dB/ppm. The detection limit of the sensor was 140 ppm and its response and recovery times were 5 s and 8 s, respectively. The results also showed that as the bending radius decreased, the response and recovery times gradually shortened, while the output power increased. In addition, the proposed sensor has advantages of a low cost and simple structure.

Silicon wafers have been widely used in the semiconductor industry for many decades. Over the past decades, with the development of organic optoelectronic materials, silicon-based organic-inorganic hybrid devices have received more and more interest in fundamental and applied research. To obtain uniform organic films for hybrid devices, superamphiphilic surfaces, on which both water and oil can spread completely, show great advantages. Herein, we prepared superamphiphilic silicon wafer surfaces with contact angles (CAs) near 0° for both water and typical organic liquids. Interestingly, lateral force mode (LFM) atomic force microscopy (AFM) images indicate that the superamphiphilicity is induced by alternating hydrophilic and hydrophobic nanodomains. By making use of these superamphiphilic silicon wafer surfaces, uniform polypyrrole (PPy) films were generated in both water and cyclopentanone, providing a versatile and effective way for the integration of organic optoelectronic materials with inorganic microelectronic devices. [ABSTRACT FROM AUTHOR]

A novel electropolymerization process has been presented to prepare compact polypyrrole (PPy) polymer films embedded with different cobalt nanoparticle (Co NP) loadings by using cyclic voltammetry. An electropolymerization mechanism is suggested and further confirmed by Fourier transform infrared (FT-IR) spectroscopy and Raman spectroscopy of pure PPy and PPy polymer nanocomposites (PNCs). The PPy/Co PNCs exhibit unique multifunctional properties. Firstly, they are superparamagnets at room temperature, whose saturation magnetization can be controlled by modifying the concentration of Co NPs in the electrolyte solution. Secondly, they show not only semiconductor transportation behavior but also a negative magnetoresistance under external magnetic field. The permittivity of the PPy/Co PNCs switches from negative to positive with the increasing frequency. Both the outstanding magnetic and electrical properties make the PPy PNCs promising as one kind of microwave absorbing materials. [ABSTRACT FROM AUTHOR]

Electron stimulated ion desorption (ESID) and degradation studies of polypyrrole doped with dodecylsulfate (PPy/DS) deposited on FTO were performed using time-of-flight mass spectrometry (TOF-MS) for ion analysis. The results suggest a strong contribution from fragments of the dodecylsulfate hydrocarbon chain to the mass spectra. In the 650-1500 eV energy range the ion yield curves show maxima at about 600, 1200 and 1400 eV, which can be related to carbon, nitrogen and oxygen-containing fragments, respectively, and interpreted in terms of the Auger Stimulated Ion Desorption (ASID) mechanism. Degradation studies indicate rapid loss of heavier hydrocarbons and an increase of bulk and substrate fragments. Some degradation profiles suggest formation of new species.

[Display omitted] • Design of a novel impedimetric immunosensor for detection of malaria biomarker. • The proposed platform is based on immobilization of egg yolk IgY antibodies onto carboxylated polypyrrole films. • The BSA/Ab- Pf HRP2(IgY)/P(Py-Py3COOH)/SPGE immunosensor exhibited good performance. • The immunosensor showed sensitivity, stability, and selectivity to Pf HRP2 antigen. This paper described an impedimetric immunosensor for detecting Plasmodium falciparum histidine-rich protein 2 (Pf HRP2). Antibodies from egg yolk (Ab- Pf HRP2, IgY type) were linked covalently to the screen-printed gold electrodes (SPGE) surface modified with a thin film of Poly-pyrrole-pyrrole 3 carboxylic acid (P(Py-Py3COOH) to develop the sensing platform. The fabrication steps were followed by microscopic (scanning electron microscopy), spectroscopic (RAMAN spectroscopy and Energy-dispersive X-ray spectroscopy), and electrochemical (electrochemical impedance spectroscopy (EIS) and cyclic voltammetry) techniques. The determination of Ag- Pf HRP2 was performed by EIS, and the BSA(bovine serum albumin)/Ab- Pf HRP2(IgY)/P(Py-Py3COOH)/SPGE immunosensor recorded a linear response at 100–1000 ng mL−1 concentration range, with a limit of detection (LOD) of 27.47 ng mL−1. Its performance was confirmed by Enzyme-Linked Immuno-Sorbent Assay. The fabricated device uses a simple strategy of IgY immobilization, showing high sensitivity and good selectivity, and can be considered an alternative for carrying out malaria tests. [ABSTRACT FROM AUTHOR]

The possibility of the modification of polyethylene terephthalate film substrate by polypyrrole films during in situ chemical oxidation of pyrrole by ammonium peroxodisulfate in 0.5 M aqueous solution of citric acid with concentrations of pyrrole in of equals 0.025 and 0.05 M has been studied. UV-vis and IR spectra of doped during synthesis by citric acid dedoped by sodium hydroxide and re-doped by citric acid polypyrrole films on polyethylene terephthalate film substrate were analyzed. The results of the morphology studies of the deposited coatings show that there are delocalized globular microformations of the macromolecules of mostly spherical shape on the background of the continuous layer of polypyrrole. [ABSTRACT FROM AUTHOR]

This work is focussed on the determination of a kinetic model and the thermodynamic study of the electrochemical entrapment of the model azo dye, Acid Red 1, at conducting polypyrrole films, which is proposed as a potential green technology for treatment of azo dyes in industrial effluents. The entrapment kinetic data were found to follow a pseudosecond order model involving an intra-particle diffusion. However, the equilibrium data obtained for Acid Red 1 entrapment at polypyrrole did not obey any common surface adsorption models such as the Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherms. Accordingly, the entrapment process may lead to an enhanced quantity of dye embedded in a polypyrrole film, making it a more effective and efficient technology than those involving only adsorption. Similarly, dye leakage from polypyrrole film surface to a sample matrix will be easily prevented. For this treatment process, a negative Δ G ∘ range between −1.46 ± 0.78 and −2.94 ± 0.24 kJ mol −1 at the corresponding temperature range of 298–318 K, and a Δ H ∘ of 20.5 ± 2.5 kJ mol −1 indicate a spontaneous and endothermic entrapment process. Also, a positive Δ S ∘ (73.6 ± 8.2 J mol −1 K −1 ) reveals increased randomness of the interface and an affinity of Acid Red 1 towards polypyrrole films. A low activation energy (7.67 ± 0.80 kJ mol −1 ) confirms a physical process for Acid Red 1 entrapment at polypyrrole films. [ABSTRACT FROM AUTHOR]

Polypyrrole films were generated on high purity aluminum substrates under anodic polarization from aqueous electrolytes comprised of pyrrole and sodium dodecylbenzene sulfonate. The methods employed to characterize the polymer films included scanning electron microscopy, Fourier-transform infrared and X-photoelectron spectroscopy and X-ray diffraction. PPY/SDBS films revealed nodular morphology with occasional appearing of "dendrites", high level of protonation, excess of counter-anions ([S]/[N] > [N+]/[N]) and high degrees of disorder.

In this paper, we demonstrate conducting polypyrrole films as a potential green technology for electrochemical treatment of azo dyes in wastewaters using Acid Red 1 as a model analyte. These films were synthesised by anodically polymerising pyrrole in the presence of Acid Red 1 as a supporting electrolyte. In this way, the anionic Acid Red 1 is electrostatically attracted to the cationic polypyrrole backbone formed to maintain electroneutrality, and is thus entrapped in the film. These Acid Red 1-entrapped polypyrrole films were characterised by electrochemical, microscopic and spectroscopic techniques. Based on a two-level factorial design, the solution pH, Acid Red 1 concentration and polymerisation duration were identified as significant parameters affecting the entrapment efficiency. The entrapment process will potentially aid in decolourising Acid Red 1-containing wastewaters. Similarly, in a cathodic process, electrons are supplied to neutralise the polypyrrole backbone, liberating Acid Red 1 into a solution. In this work, following an entrapment duration of 480 min in 2000 mg L −1 Acid Red 1, we estimated 21% of the dye was liberated after a reduction period of 240 min. This allows the recovery of Acid Red 1 for recycling purposes. A distinctive advantage of this electrochemical Acid Red 1 treatment, compared to many other techniques, is that no known toxic by-products are generated in the treatment. Therefore, conducting polypyrrole films can potentially be applied as an environmentally friendly treatment method for textile effluents. [ABSTRACT FROM AUTHOR]

Using AFM, adhesion (shear stresses are applied over more than 5 orders of magnitude) and conductivity measurements, we analyze the synthesis of polypyrrole (PPy) films in water by means of the oxidation of pyrrole by Fe 3+ cations. The PPy polymer chains that result, are composed of conjugated bounds which are conductive when appropriately doped, with Cl − ions here, for providing the necessary electric charge carriers. Two processes are available. At low concentrations of the reactants, below a volume polymerization threshold, a PPy film is directly synthesized on the substrates thanks to catalytic sites that reduce the activation energy of the reaction. Above the volume polymerization threshold, PPy aggregates appear everywhere in the bulk of the solution. After diffusion, they settle on the solid surfaces. The aggregates exhibit crushed irregular shapes at the AFM, that contrast with the rounded shape and the similar size of the dendrites synthesized in the surface polymerization regime. The film, being made of drop-off aggregates, is powdery, soft and labile, poorly conductive if not compressed. Below the volume polymerization threshold, conversely, the PPy film exhibits enhanced mechanical and conductivity properties thanks to numerous cross-links between the PPy chains. At lower concentrations of the reactants, below a percolation threshold, the film is isolating. The conductivity and the film thickness variations with the reactant concentrations and the reaction time appear to be consistent with a second-order kinetics in the surface polymerization regime. Except for the catalytic effects, the volume polymerization reaction works similarly. It exhibits a second-order kinetics too, which is consistent with a volume polymerization threshold obeying the relation [Py] [FeCl 3 ] = 5.5 × 10 −4 mol 2 L −2 . The saturation of the conductivity of the PPy films at large reaction times in the surface polymerization regime, and its slowing-down in the volume polymerization regime indicate that the catalytic sites on the surface get masked after a couple of hours of synthesis time. The PPy conductivity in the surface polymerization regime is measured to be in the range 10–60 S m −1 when no compression is exerted on the film. These conditions appear to be appropriate for coating silica particles with a stiff and conductive PPy film. [ABSTRACT FROM AUTHOR]

Abstract: Polypyrrole (PPy) films doped by p-toluenesulfonic (PTS) ion were prepared by pulse current polymerization (PCP PPy) and direct current polymerization (DCP PPy) in aqueous solution. During polymerization of DCP PPy films, the sustained high anodic potentials can result in overoxidation and –CH2– formation at pyrrole rings, which was confirmed by the FTIR spectroscopy. PCP PPy films exhibited more homogeneous and smoother appearance than DCP PPy films. The apparent diffusion coefficient of PCP PPy films was one order of magnitude bigger than that of DCP PPy films, which was closely correlated with the more ordered structure of PCP PPy films confirmed by XRD. When the scanning rate reached up to 500mVs−1, the CV curves of PCP PPy films showed rectangular shape within voltage range of −0.8V to +0.8V. High charge/discharge rate of PCP PPy films can be attributed to well wettability, very small charge transfer resistance, high electronic conductivity and ions apparent diffusion coefficient. After 50,000 charge/discharge cycles, the specific capacitance of PCP PPy films only decreased by 14% at a charge/discharge current of 20Ag−1 within voltage range of 0–0.4V. [ABSTRACT FROM AUTHOR]

Abstract: Ionic desorption from polypyrrole films doped with dodecylsulfate as counter anion (PPyDS) deposited onto fluorine tin oxide glass (FTO) was studied through electron (ESID) and photon (PSID) stimulated ion desorption techniques, employing time-of-flight mass spectrometry (TOF-MS) for ion analysis. ESID results suggested strong contribution from DS fragments to the mass spectra. In the 650–1500eV energy range the relative desorption ion yield curves show maxima at about 700, 1200 and 1400eV, which may be related to carbon, nitrogen and oxygen containing fragments, respectively, and interpreted in terms of the Auger stimulated ion desorption (ASID) mechanism. For energies greater than 1500eV, the secondary electrons play an important role in the ion formation. PSID studies were performed at the Brazilian Synchrotron Light Source (LNLS) covering the sulphur K-shell photoexcitation during a single-bunch operation mode of the storage ring. Ionic desorption of atomic and molecular fragments were also observed. Relative desorption ion yield curves have been determined as a function of the photon energy, indicating that at the photon energy region covered by the PSID studies the indirect XESD (X-ray induced electron stimulated desorption) process plays an important role in the ionic desorption of PPyDS irradiated by soft X-rays. [Copyright &y& Elsevier]

Abstract: A dipyridylamine ligand with a pendant pyrrole (N-(3-N,N′-bis(2-pyridyl)propylamino)pyrrole, PPP) and its corresponding rhenium(I) complex, Re(CO)3(κ2-N,N-PPP)Cl, were synthesized. The structure of Re(CO)3(κ2-N,N-PPP)Cl was determined by X-ray crystallography. Electrochemical polymerization of the pyrrole moiety resulted in the immobilization of poly[Re(CO)3(κ2-N,N-PPP)Cl] film onto a glassy carbon electrode, which exhibited electrocatalytic activity for the reduction of CO2 to CO. [Copyright &y& Elsevier]

Abstract: A novel O-butyryl chitosan (OBCS)-grafted polypyrrole (PPy) film was described. The immobilization was accomplished by photocrosslinking the OBCS onto PPy films under ultraviolet light irradiation. The surfaces of OBCS-grafted PPy film were characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy and electron spectroscopy for chemical analysis (ESCA). The blood compatibility of the OBCS-grafted PPy film was evaluated by platelet-rich plasma (PRP) contacting experiments and protein adsorption experiments in vitro. These results have demonstrated that the surface with immobilized OBCS shows much less platelet adhesive and fibrinogen adsorption compared to the control surface. The bulk conductivity values of PPy films were measured by a modified four-probe method. The composite films have both good blood compatibility and high electrical conductivity that make them suitable for using as potential biomaterials, such as electrically conducting blood vessel and functionally haemocompatible substrate of biosensor used directly in whole blood. [Copyright &y& Elsevier]

Abstract: For many years, polypyrrole films have appeared to be the most studied conducting polymer. Unfortunately, shadows still remain concerning the electrochemical mechanisms of these films and in particular, the aspect which concerns the limiting step which governs the electrochemical response. Different possibilities are available such as the transport of ionic species in the film, the electron transfer at the electrode/film or the electron motion in the film, the ionic exchanges at the film/interface electrolyte. Classical electrochemical methods do not permit to discriminate between these effects. Ac-electrogravimetry technique was used here to demonstrate that the electrochemical behaviour of thin pPy films is governed by the ionic insertion without any doubt. Particular parameters were modified as the ionic atomic weight or the electrolyte concentration to corroborate this idea. [Copyright &y& Elsevier]

Abstract: The use of electrochemically synthesized polypyrrole (a conducting polymer) film is investigated as a primer for protective coating on carbon steel. It provides excellent adherence and corrosion resistance, and is more environment-friendly. Polypyrrole was galvanostatically synthesized on carbon steel, and epoxy paint top coat was applied on it. The corrosion performance was evaluated using salt spray test, Tafel plots, and electrochemical impedance spectroscopy. The performance was compared to that of a commercial zinc primer. These tests coherently demonstrate that the use of polypyrrole film inhibits corrosion better than a zinc primer in salt and acid environments. [Copyright &y& Elsevier]

Polypyrrole films were electrosynthesized on mild steel with oxalic acid electrolyte at varying temperatures (25–65 °C), current density (0.5–6.0 mA/cm2) and pH (2.0, 4.0, 7.0 and 8.5). The concentrations of pyrrole and oxalic acid were maintained at 0.1 M each in galvanostatic experiments. The results show that lower temperatures favor the formation of polypyrrole on mild steel in acidic media. At higher temperature and lower current densities, oscillations in electrode potentials were observed. The film quality was poorest at pH 7.0, while very adherent and compact films were obtained in alkaline medium. Higher temperature in alkaline media favors the formation of better polypyrrole films in contrast with acidic media. [Copyright &y& Elsevier]

We report in this work the organosilane modification of ITO substrates and subsequent electrodeposition of polypyrrole films. First, n-hexyltrichlorosilane (HTCS) and 6-(1′-pyrrolyl)-n-hexyltrichlorosilane (PyHTCS) were grafted on ITO substrates. The resulting monolayers were qualified by X-ray photoelectron spectroscopy, contact angle measurements and cyclovoltammetry, and they were found to be dense and well-covering. Second, pyrrole was electrochemically polymerized on modified ITO substrates in acetonitrile and aqueous solutions. Chronoamperometry was used to study the effect of the monolayers on polypyrrole growth kinetics. PyHTCS monolayers, compared to bare substrates, accelerate the polymer growth while HTCS monolayers delay and slow down the polymer growth. Qualitative peel tests and scanning electron microscopy (SEM) further evidenced the beneficial effect of PyHTCS monolayers. Polypyrrole grown from PyHTCS monolayers were found to be more uniform and more adherent, compared to bare and HTCS-modified ITO substrates. Cyclic voltamograms gave some additional indications in this sense. UV spectroscopy revealed differences in polymer quality arising from growth solutions: acetonitrile leads to better quality polymer films than aqueous solutions. [Copyright &y& Elsevier]

The incorporation of antibody to Listeria into polypyrrole films during electropolymerisation and the covalent attachment of these antibodies to the conducting polymer backbone after polymerisation have been investigated. While the former approach provides a simple and convenient means of immobilisation, enzyme-linked immunosorbent assay tests have shown that covalent attachment produces a more bioactive surface and greatly improved reproducibility. [Copyright &y& Elsevier]

Cd2+ sensors play an essential role in biology and environment. We adopted the post-modification and interfacial polymerization strategies to realize a free-standing and homogeneous filmy Cd2+ electrochemical sensor by copolymerizing MOF-867 nanocrystals with pyrrole monomers. This hybrid film exhibited good structural integrity and retained Cd2+ sensing behavior with good conductivity in a covalent film form. This poly-MOF hybrid film exhibited a highly excellent sensing selectivity and sensitivity for Cd2+ with a very low detection limit around 0.29 μg L−1, lower than pure MOF-867 and significantly below the standard for Cd2+ in drinking water, which benefited from the devisable architectures of MOF-867 with the good conductivity of PPy polymer matrix. This work highlighted a simple strategy for poly-MOF film formation and accelerated the MOFs-based materials for Cd2+ electrochemical sensing in practical applications. In this work, we presented a MOFs@PPy composite film prepared by covalently embedding MOFs into the surface of PPy films. And this hybrid film exhibited excellent Cd2+ electrochemical sensing behavior. [Display omitted] • A conductive poly-MOF free-standing and homogeneous filmy electrochemical sensor. • This MOFs-based hybrid film exhibited high sensory performances to Cd2+. • A simple strategy for fabricating chemical bonds between MOFs particles and polymers. [ABSTRACT FROM AUTHOR]

Very adherent modified polypyrrole (PPy)m films have been electrosynthesized on oxidizable metals such as mild steel (MS) and zincated steel (Zn) by electrochemical oxidation of pyrrole (Py) on the substrate. In the case of mild steel, the adherence of the coating is maintained in both the oxidized and reduced states of the polymer, allowing the cataphoretic print technique, which is particularly useful in the automotive industry, to be used. When submitted to the salt spray test, the bilayer system (MS/(PPy)m/cataphoretic paint) appears to be as good as the reference system where the PPy layer has been replaced by a phosphating layer. [ABSTRACT FROM AUTHOR]

The three polypyrrole (PPy) films with different mixture ratios, namely PPy1, PPy2, and PPy3, were synthesized by chemical oxidation with pyrrole and ferric chloride (FeCl3). The roughened plastic optical fiber (POF) taper assembled PPy films (POF-PPy1, POF-PPy2, and POF-PPy3) were facilely prepared and bent U shape structure for testing ethanol gas at room temperature. The morphologies of the PPy films and the roughened POF taper were studied using electron microscopy. The effect of the three PPy films on the gas response was investigated and the results showed that the POF-PPy2 exhibited a high sensitivity of 5.08 × 10−5 dB/ppm. The detection limit of the sensor was 140 ppm and its response and recovery times were 5 s and 8 s, respectively. The results also showed that as the bending radius decreased, the response and recovery times gradually shortened, while the output power increased. In addition, the proposed sensor has advantages of a low cost and simple structure. [ABSTRACT FROM AUTHOR]

Isoproturon-imprinted polypyrrole films were electrochemically synthesized onto glassy carbon (GC) electrodes in an ethanol/aqueous solution of pyrrole as a monomer, isoproturon as a template molecule and LiClO 4 as supporting electrolyte. Electropolymerization was performed by cyclic voltammetry and chronoamperometry. The isoproturon template molecules were successfully trapped in the polypyrrole film where they created artificial recognition cavities. After the electrochemical extraction of the template, the polypyrrole film acted as a molecularly imprinted polymer (MIP) for the selective recognition of isoproturon whereas the non-imprinted polymer (NIP) film, made in the same conditions except for the presence of isoproturon, did not exhibit any interaction. The MIP and NIP films were characterized by cyclic voltammetry in the presence of redox probes and the thickness of the polymer layers was estimated by EQCM (Electrochemical Quartz Crystal Microbalance) and calculated using Faraday's law. The isoproturon-imprinted polypyrrole films were found to selectively detect isoproturon even in the presence of the interferents carbendazim and carbamazepine. Its limit of detection (LOD) in milli Q water, achieved via square wave voltammetry was as low as 0.5 μg L−1, whereas in real water samples it was found to be 2.2 μg L−1. Image 1 • Novel electro-synthesized isoproturon molecularly imprinted polymer modified electrode. • Sensitive and selective Isoproturon molecular imprinted polypyrrole sensor. • Correlation between the MIP electropolymerization conditions and its properties. • Isoproturon detection in real water matrice. [ABSTRACT FROM AUTHOR]

Surface Chemistry In their Communication on page 5720 ff., Y. Tian and co‐workers report the generation of super‐amphiphilic silicon wafer surfaces with alternating hydrophilic/hydrophobic nanodomains, upon which uniform polypyrrole films can be formed. [ABSTRACT FROM AUTHOR]