Synthesis and properties of conducting polypyrrole,polyalkylanilines, and composites of polypyrrole and poly(2‐ethylaniline)

Conducting polymers of alkylanilines, pyrrole, and their conducting composites were synthesized by oxidation polymerization. The oxidants used were KIO₃ and FeCl₃ for the polyalkylanilines and polypyrrole (PPy), respectively. Among the polyalkylanilines synthesized with KIO₃ salt, the highest conductivity was obtained with poly(2‐ethylaniline) (P2EAn) with a value of 4.10 × 10^?5 S/cm. The highest yield was obtained with poly(N‐methylaniline) with a value of 87%. We prepared the conducting composites (PPy/P2EAn and P2EAn/PPy) by changing synthesis order of P2EAn and PPy. The electrically conducting polymers were characterized by IR spectroscopy, ultraviolet–visible spectroscopy, thermogravimetric analysis, and X‐ray diffraction spectroscopy. From the results, we determined that the properties of the composites were dependent on the synthesis order of the polymers. The thermal degradation temperature of PPy was observed to be higher than that of the other polymers and composites. We determined from X‐ray results that the structures of the homopolymers and composites had amorphous regions (88–95%) and crystal regions (5–12%). From the Gouy balance magnetic measurements, we found that the polymers and composites were bipolaron conducting mechanisms. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 241–249, 2006     

Chemical synthesis,characterization, and direct‐current conductivity studies of polypyrrole/γ‐Fe2O3 composites

The in situ polymerization of pyrrole was carried out in the presence of γ‐Fe₂O₃ to synthesize polypyrrole/γ‐Fe₂O₃ composites by a chemical oxidation method. The polypyrrole/γ‐Fe₂O₃ composites were synthesized with various compositions, including 10, 20, 30, 40, and 50 wt % γ‐Fe₂O₃ in pyrrole. The polypyrrole/γ‐Fe₂O₃ composites were characterized with X‐ray diffractometry and infrared spectroscopy. The surface morphology of these composites was studied with scanning electron microscopy. The direct‐current conductivity was studied from 40 to 200°C. The dimensions of the γ‐Fe₂O₃ particles in the matrix had a greater influence on the conductivity values. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 2797–2801, 2007     

Molecularly imprinted polypyrrole prepared by electrodeposition for the selective recognition of tryptophan enantiomers

Herein we report the electrosynthesis of polypyrrole with L ‐tryptophan (L ‐Trp) as a template to prepare molecularly imprinted polymers (MIPs). Overoxidized polypyrrole films with cavities complementary to the template were used for the enantioselective detection of L ‐Trp and D ‐tryptophan (D ‐Trp). Important parameters, such as the electropolymerization potential, overoxidization potential and time, thickness of the polypyrrole films, and scanning rate of the stripping voltammetric experiments, were varied to achieve an optimum sensor response. We found that L ‐Trp was inserted about 2 times higher into the imprinted polymer film than D ‐Trp. Also, in this study, an electrochemical quartz crystal microbalance technique was used to investigate the performance of overoxidized polypyrrole films. The enantioselectivity of the MIPs was attributed to the cavities in the imprinted films, which were complementary to the target molecules, both in shape and in positioning of the functional groups. The results also suggest the feasibility of preparing MIPs by electropolymerization for the enantioselective recognition of other amino acid enantiomers. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis and characterization of polypyrrole rod doped with p‐toluenesulfonic acid via micelle formation

Rod‐type polypyrrole (PPY) doped with p‐toluenesulfonic acid (TSA) was synthesized by chemical oxidative polymerization via a self‐assembly process. The shape of the PPY particles is mainly determined by the ratio of TSA/pyrrole (PY) and feed rate of the oxidant. Particle of different shapes (rod, grain, and partially rod) exhibit differences in morphology, electrical properties, dispersity, and thermal properties. Wide‐angle X‐ray diffraction patterning analysis was used to investigate the mechanism of rod formation. The effect of the TSA concentration on the PPY structure was investigated using Fourier transform infrared spectroscopy. The PPY rods doped with TSA exhibited better electrical conductivity than granular PPY doped with TSA, and their dispersity and thermal stability were also higher. Self‐orientation of PPY in the micelles of TSA and high crystallinity of the rod particles led to improved thermal stability. Hence, the decomposition temperature of the polymer chain was considerably increased. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Preparation and characterization of polypyrrole/modified multiwalled carbon nanotube nanocomposites polymerized in situ in the presence of barium titanate

Polypyrrole (PPy) composites were prepared with both unmodified and amine‐modified multiwalled carbon nanotubes (MWCNTs) in the presence and absence of barium titanate (BaTiO₃) by in situ oxidative polymerization. A uniform coating of PPy on the MWCNTs and BaTiO₃ surfaces was confirmed by field emission scanning electron microscopy and high‐resolution transmission electron microscopy images. The structure of the pure and amine‐modified MWCNTs were identified by Fourier transform infrared spectroscopy. The incorporation of BaTiO₃ enhanced the thermal stability and capacitance properties of the composites. The maximum specific capacitance and energy density values found for the PPy/amine‐modified MWCNT/BaTiO₃ composites were 155.5 F/g and 21.6 W h/kg, respectively, at a scan rate of 10 mV/s. The maximum power density was found to be 385.7 W/kg for the same composite at a scan rate of 200 mV/s. Furthermore, the impedance spectra of the composites showed moderate capacitive behavior. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis,characterization, and conductivity studies of polypyrrole/copper sulfide nanocomposites

Nanocomposites of polypyrrole (PPy) containing copper sulfide (CuS) were synthesized by an in situ chemical oxidative polymerization. The nanocomposites were characterized by FTIR, SEM, XRD, DSC, TGA, and conductivity studies. The FTIR spectra ascertained the chemical interlinking of polypyrole with metal sulfide nanoparticles. Morphological analysis showed that the nanoparticles were uniformly covering the entire substrate. The XRD pattern reveals that the nanoparticle incorporated polypyrrole showed a crystalline nature and the crystallinity of the polymer increases with increase in concentration of CuS nanoparticles. From DSC, an increase in glass transition temperature shows the increased orderness in the polymer composite than in the pure polypyrrole. Thermal analysis (TGA) of the composite showed a progressive increase in the thermal stability with increase in content of CuS. The frequency dependent electrical properties (a.c. conductivity) of the nanocomposites were higher than that of polypyrrole. The d.c. electrical conductivity increased with increase in amount of nanoparticles in the polymer matrix. The results obtained for these composites have greater scientific and technological interest. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Soluble and conductive polypyrrole copolymers containing silicone tegomers

Soluble and processable conductive copolymers of silicone tegomers and pyrrole were developed. This was easily accomplished by the oxidative polymerization of pyrrole monomer by Ce(IV) salt in the presence of silicone tegomers with hydroxyl chain ends. The resulting copolymers were soluble in dimethylformamide. The products were characterized by Fourier transform infrared, ¹H‐NMR, and four‐point probe conductivity, and their surface properties were investigated with contact‐angle measurements. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2896–2901, 2003     

Investigation of the electroactivity,conductivity, and morphology of poly(pyrrole‐co‐N‐alkyl pyrrole) prepared via electrochemical nanopolymerization and chemical polymerization

The copolymerization of pyrrole (Py) with N‐ethyl pyrrole, N‐butyl pyrrole, and N‐octyl pyrrole (NOPy) was carried out by electrochemical and chemical oxidation. In the electrochemical method, copolymer thin films with different feed ratios of monomers were synthesized by the cyclic voltammetry method in a lithium perchlorate (LiClO₄)/acetonitrile (CH₃CN) electrolyte on the surface of a glassy carbon working electrode. The deposition conditions on the glassy carbon, the influence of the molar ratios of the monomers on the formation of the copolymers, and the electroactivity of the copolymers were investigated with cyclic voltammetry. Nanoparticles made of a conjugate of the copolymers with different feed ratios of monomers were prepared by chemical polymerization (conventional and interfacial methods) in the presence of iron(III) chloride hexahydrate (FeCl₃·6H₂O) as the oxidant. Nanostructural copolymers with higher conductivities were synthesized by simple tuning of the preparation conditions in a two‐phase medium. Fourier transform infrared spectroscopy, scanning electron microscopy, and four‐probe conductivity measurement techniques were applied for the characterization of the obtained copolymers. The conductivity of the obtained copolymer by an interfacial method with chloroform as the organic phase was 20 times higher than the copolymer obtained via an interfacial method with toluene as the organic phase and 700 times higher than the copolymer prepared by the conventional method (for a molar ratio of 70 : 30 Py : NOPy). © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Morphology control of conducting polypyrrole nanostructures via operational conditions in the emulsion polymerization

Polypyrrole (PPy) nanostructures with diameter smaller than 100 nm were synthesized by chemical oxidative polymerization of pyrrole in the presence of cetyl trimethylammonium bromide and sodium dodecyl sulfate as surfactants. Hydrochloric acid was used as dopant, and a solution of potassium peroxydisulfate was used as initiator. The influence of polymerization temperature, feeding strategy, and the type of surfactant on the morphology and conductivity of PPy nanostructures were investigated and well‐described. A simple route just via controlling the operational conditions in the emulsion polymerization is reported to obtain nanostructured PPy with desirable morphology and relatively good conductivity. The analysis results demonstrated that the conductivity of samples is highly affected by their morphology whereas PPy nanofibers exhibited higher conductivity respecting the other morphologies (0.66 S/cm). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44697.     

Novel route to pure and composite fibers of polypyrrole

An organic salt (FeAOT) is synthesized by the reaction of sodium 1,4‐bis(2‐ethylhexyl)sulfosuccinate (AOT) and ferric chloride. It is fabricated into fibers by manual drawing and electrospinning. Long polypyrrole (PPy) fibers are obtained for the first time by a vapor deposition reaction of pyrrole on the FeAOT fibers, and this technique is extended to the synthesis of PPy composite fibers with multiwalled carbon nanotubes (PPy–MWCNT fibers). The PPy and PPy–MWCNT fibers have a nanoporous morphology, a conductivity of 10–15 S cm^?1, and a tensile strength of 12–43 MPa. The electrochemistry and current–voltage characteristics of the PPy fibers are also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1490–1494, 2007     

Humic acid/polypyrrole on a paraffin‐impregnated graphite electrode and its use in arsenic extraction

A novel and simple electrode with rapid preparation was developed with humic acid (HA) and polypyrrole (PPy) films. The method for modified electrode preparation embraced the abrasive transfer technique on a paraffin‐impregnated graphite electrode (PIGE) followed by the electrochemical incorporation of a PPy polymeric film upon bare PIGE and PIGE/HA electrodes. Cyclic voltammetry, electrochemical impedance spectroscopy, and chronoamperometry were used for the study of the modified electrodes. Morphological characterization was performed by scanning electron microscopy. The obtained results demonstrated that the presence of HA did not affect the electrical properties of the system but indeed provoked changes in the polymer morphology, turning it more granular. Next, PIGE/HA/PPy was tested in arsenic solutions [As(V)] because arsenic contamination of water is an important worldwide environmental issue because of the sources of arsenic contamination of water come from both natural processes and anthropogenic activities. The modified electrode displayed good and reversible extraction properties toward the analyte in acid medium and was 18% more efficient than a previously reported PPy‐modified electrode (PIGE/PPy). From an environmental standpoint, this novel application of conductive polymer properties with the chelating capacity of humic substances constitutes a first step in the development of more efficient technologies for the removal of contaminants present in soil–water media. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Immobilization of invertase in conducting polypyrrole/PMMA‐co‐PMTM graft copolymers

In this study, invertase was immobilized in copolymer electrodes constructed. Three different types of polymethyl methacrylate‐co‐polymethyl thienyl methacrylate matrices were used to obtain copolymers that were characterized by FT‐IR spectroscopy. Immobilization of enzymes was carried out by the entrapment of the enzyme in conducting polymer matrices during electrochemical polymerization of pyrrole through thiophene moieties of polymers. Immobilization of the enzyme was achieved by application of 1.0 V constant potential on a platinum electrode for 30 min in solution. The effects of temperature and pH on the activity of the enzyme electrodes were examined and operational stability studies were done. The changes in the maximum reaction rate and the variations in the Michaelis–Menten constant were studied. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 502–507, 2005     

Mechanical properties of conducting H‐type polysiloxane–polypyrrole graft copolymers and polytetrahydrofuran–polypyrrole block copolymers

The mechanical properties of block copolymers of polypyrrole and pyrrolyl‐ended azobis‐polytetrahydrofuran (TPPy) and graft copolymers of pyrrolyl‐ended H‐type polydimethylsiloxane (SPPy) were investigated and compared with those of polypyrrole (PPy). Conducting films were prepared electrochemically at a constant potential and doped with p‐toluene sulfonate. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1663–1666, 2002     

Application of polypyrrole to flexible substrates

Conducting polymers such as polypyrrole may be useful in smart packaging products, provided application methods can be developed that circumvent the insolubility and infusibility of these materials. Experiments were conducted in five research areas relevant to the application of polypyrrole to nonrigid substrates. The studies reveal that application of polypyrrole from the liquid phase, either by deposition from depleted bulk solution or inkjet printing dispersions, is unlikely to give films as regular as those produced by vapor phase polymerization. Using the latter approach, two potential methods of applying patterned polypyrrole films to nonrigid substrates were developed. The first used hypochlorite to pattern a continuous film of polypyrrole, previously applied by vapor phase polymerization. The second used inkjet printing to apply an oxidant solution, whose pH had been raised with a volatile base, to nonrigid substrates. The higher pH reduced corrosion of the print head, increasing the lifetime of printers exposed to oxidative compounds. The base was subsequently evaporated by heating, and the dried oxidant used as a template for vapor phase polymerization of polypyrrole. This method gave smooth, shiny and adherent polypyrrole films on papers and polyester transparency, with high resolution. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3938–3947, 2007     

Polyaniline and polypyrrole prepared in the presence of surfactants: a comparative conductivity study

Polyaniline and polypyrrole have been prepared by chemical oxidative polymerization of the corresponding monomers in an aqueous medium containing an anionic surfactant—sodium bis(2-ethylhexyl) sulfosuccinate, dodecylbenzenesulfonic acid and its sodium salt, and sodium dodecyl sulfate. Determination of the yield, elemental composition and density proved, and FTIR spectroscopy confirmed, that the anionic surfactants become incorporated in the conducting polymers. The polymerizations in the presence of a cationic surfactant, tetradecyltrimethylammonium bromide, were carried out for comparison. While the conductivity of polypyrrole became enhanced after the introduction of an anionic surfactant, the changes in the conductivity of polyaniline were marginal. The conductivity changes in both polymers during thermal ageing were measured at 175 °C. The electrical stability of polyaniline was better than that of polypyrrole. The presence of a surfactant improved the stability of conductivity of polypyrrole but reduced the electrical stability of polyaniline.     

Electrical conductivity enhancement of spin‐coated PEDOT:PSS thin film via dipping method in low concentration aqueous DMSO

The electrical conductivity of poly(3,4‐ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) was enhanced by dipping the thin films prepared by spin coating technique in an aqueous DMSO solution. The low concentration range of DMSO in water between 0–5 vol % was studied in comparison with pure water and pure DMSO. It was found that the electrical conductivity dramatically increased as increasing the concentration of DMSO and reached the constant value of 350 S cm^?1 at 2 vol % of aqueous DMSO solution. This could be explained by the conformational change of PEDOT chains from the coil structure to the linear or expanded coil structure as confirmed by Raman spectra. Further, white patches were obviously noticed on the surface of the films dipped in pure DMSO, indicating the phase separation of conductive PEDOT grains and associated PSS. The sulfur element of the dipped film surface was investigated by XPS. The XPS S2p core‐level spectra displayed that the unassociated PSS was considerably removed from the surface of PEDOT:PSS films dipped in pure water and 2 vol % of aqueous DMSO solution, indicating that the presence of water in the solvents is important to prominently promote the washing effect. Finally, UV–Vis spectra revealed the improved transparency of the films probably owing to the decreased film thickness. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42108.     

Chemical polymerization of pyrrole in the presence of ketone–formaldehyde resins

The chemical polymerizations of pyrrole in the presence of acetophenone and formaldehyde, cyclohexanone, acetaldehyde, and formaldehyde, cyclohexanone and formaldehyde, cyclohexanone, resorcinol, and formaldehyde, cyclohexanone and lignosulfonate formaldehyde, and cyclohexanone, pyrrole, and formaldehyde were accomplished with Ce(IV) salt in acetonitrile solutions. The roles of the resin type, the addition order of the reactants, and the concentrations of the pyrrole and resin on the solubility and conductivity of the resulting products were investigated. The cyclohexanone–acetaldehyde–formaldehyde resin/polypyrrole copolymer had the highest solubility in dimethylformamide. The conductivity and solubility of the copolymers could be controlled by the Ce(IV)/pyrrole/resin molar ratio. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 618–624, 2005     

Improvement of adhesion and continuity of polypyrrole thin films through surface modification of hydrophobic substrates

Conducting polymer polypyrrole is reported to have a poor adhesion to substrate which limits its applicability as thin films. In this article, we report synthesis of well‐formed and continuous film of polypyrrole through treatment of hydrophobic substrates. However, in place of the widely used organosilanes, the substrates were simply treated with surfactant cetyl trimethylammonium bromide (CTAB) prior to vapor phase polymerization under controlled environment. Polypyrrole films formed on CTAB pretreated substrates were found to have improved adhesion and continuity compared to the films formed on untreated substrates. The improved adhesion results in better electronic properties as seen during Electron field emission studies. Based on contact angle analysis, we propose that CTAB molecules act as anchoring agents for the oxidant layer on the substrate and hence assist in the deposition of a more continuous polypyrrole film. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39771.     

Potassium persulfate-mediated preparation of conducting polypyrrole/polyacrylonitrile composite fibers: Humidity and temperature-sensing properties

Conducting polypyrrole (PPy)/polyacrylonitrile (PAN) composite fibers were prepared by the polymerization of pyrrole in the presence of PAN fibers with potassium persulfate in an acidic aqueous solution. We obtained composite fibers containing concentrations of PPy as high as 1.14% and having surface resistivities as low as 0.6 kΩ/cm² by changing the polymerization parameters, including the temperature and concentrations of pyrrole and oxidant. The tensile strength of 10.02 N/m² and breaking elongation of 32.68% for the pure PAN fiber increased up to 10.45 N/m² and 33.23%, respectively, for the composite fiber containing 0.13% PPy. The change in the resistivity of the PPy/PAN composite fiber during heating–cooling cycles in the temperature range of +5 to 120°C was examined. Scanning electron microscopy and optical microscopy images of the composite fibers showed that the PPy coating was restricted to the surfaces of the PAN fibers. Surface resistivity measurements, Fourier transform infrared spectroscopy, and thermogravimetric analysis techniques were also used to characterize the composite fibers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Synthesis and properties of soluble polypyrrole doped with dodecylbenzenesulfonate and combined with polymeric additive poly(ethylene glycol)

Soluble polypyrrole (PPy) samples advanced in electrical conductivity σ were chemically synthesized with dodecylbenzenesulfonate (DBS) sodium salt as a dopant, with poly(ethylene glycol) (PEG) as an additive, and with ammonium persulfate as an oxidant. The PPy–DBS–PEG samples were soluble in organic solvents (N‐methylpyrrolinone and m‐cresol). The greater the molar percentage ratio was of DBS, the greater the solubility was of synthesized PPy composites (PPy–DBS–PEG). The maximum electrical conductivity at room temperature for PPy–DBS–PEG was 1.02 S/cm, which was in fact the true conductivity of 100/10 (mol %) PPy/DBS. The chemical composition and doping level of PPy–DBS–PEG were determined by elemental analysis. The results of Fourier transform infrared spectroscopy were used for the structural characterization of PPy–DBS–PEG. The scanning electron microscopy results showed that the electrical conductivity was related to the morphology of PPy–DBS–PEG. According to thermogravimetric analysis, PPy–DBS–PEG was more thermostable than PPy–DBS. Electron spin resonance measurements showed that the polaron and bipolaron acted as charge carriers of PPy–DBS–PEG. According to the temperature dependence of the electrical conductivity, PPy–DBS–PEG was a semiconductor and followed the three‐dimensional variable‐range hopping model. The improved electrical conductivity apparently resulted from the reduction of the crosslinking and structural defects of the PPy chains. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 97: 1170–1175, 2005