Synthesis and characterization of electrically conducting copolymers based on benzene and biphenyl

Poly(p‐phenylene) (H‐PPP), which is one of the firstly investigated conducting polymer, has the disadvantage of difficult processability because it is infusible and insoluble. The use of biphenyl instead of benzene leads to ortho‐, meta‐, para‐polyphenylenes (H‐PP) which are more soluble and easier to be processed, however their electrical conductivity is lower. Copolymers of polyphenylenes (C₁ and C₂) and corresponding homopolymers (H‐PPP and H‐PP) were produced by the oxidative cationic polymerization of benzene and/or biphenyl. The soluble (‐S) and the insoluble (‐I) in chlorobenzene polyphenylenes were separated (H‐PP‐I, H‐PP‐S, C₁‐I, C₁‐S, C₂‐I, and C₂‐S) and they were doped with a solution of FeCl₃. All polyphenylenes were studied by FTIR, XRD, TGA, and their electrical conductivity with constant current was determined. Pronounced differences between the copolymers and the homopolymers were observed, indicating the different structure of the former. The values of the electrical conductivity of doped insoluble copolymers (10^?4 and 10^?5 S/cm) are between that of H‐PPP (10^?3 S/cm) and H‐PP‐I (10^?6 S/cm). The values of the electrical conductivity of doped soluble copolymers (10^?5 S/cm) are considerably higher than that of H‐PP‐S (10^?9 S/cm). The new electrically conductive polyphenylenes that were produced differ significantly from the corresponding homopolymers and combine good electrical conductivity and solubility. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

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     

The preparation and electrical conductivity of polyacrylamide/graphite conducting hydrogel

Polyacrylamide/graphite superabsorbent composite was synthesized by free radical polymerization of acrylamide monomer using N,N′‐methylene‐bis‐acrylamide as crosslinker, potassium persulfate as initiator, and graphite as functional filler. On the basis of the superabsorbent composite, a hydrogel with a conductivity of 0.86 mS cm^?1 was obtained. The preparation conditions were optimized. The influence of crosslinker, initiator, monomer, graphite, water absorbency, and temperature on the conductivity of the hydrogel was investigated, an adsorbed network structure model for polyacrylamide/graphite conducting hydrogel was purposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Preparation and characterization of exfoliated organic montmorillonite/poly(3,4‐ethyldioxythiophene) nanocomposites

Montmorillonite, organically modified by octadecylammine salt, has been adopted to successfully fabricate the exfoliated organic montmorillonite/poly(3,4‐ethyldioxythiophene) (OMMT/PEDOT) nanocomposites by in situ polymerization in aqueous media. Hydrochloric acid, 1,5‐naphthalenedisulfonic acid, and sodium benzenesulphonate have been employed to activate the polymerization of 3,4‐ethyldioxythiophene by offering active sites on the layers of montmorillonite. The resulting exfoliated nanocomposites have been characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, X‐ray diffraction, thermogravimetric analysis, and electrical conductivity measurement and showed controllable conductivity in the range of 10^?7 to 10^?2 S/cm and improved thermal stability compared with pure PEDOT. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Photo‐induced protonation and conductivity of polyaniline/poly(ethylene glycol) and polyaniline/[poly(ethylene glycol)‐grafted polyaniline] composites

Composites of polyaniline in its emeraldine base form (PANI‐EB) and photo‐acid generators (PAG) show an increase in conductivity upon photo‐irradiation due to the protonation of PANI‐EB. Such materials may be utilized to fabricate conducting patterns by photo‐irradiation. However, the conductivity obtained by direct irradiation of PANI‐EB/PAG composites was normally quite low (<10^?3 S/cm) due to aggregation of highly loaded PAG. In this work, poly(ethylene glycol) (PEG), which is a proton transfer polymer, was added to PANI‐EB/PAG. Results showed that addition of low M_w (550) PEG significantly enhance the photo‐induced conductivity. Conductivities as high as 10^?1–10⁰ S/cm were observed after photo‐irradiation. This conductivity is comparable to that of PANI‐salt synthesized by oxidizing aniline in the presence of an acid. High M_w (8000) PEG is much less effective than PEG 550, which is attributed to its lower compatibility with PANI. PEG‐grafted PANI (N‐PEG‐PANI) was also studied as an additive. Composites of PANI‐EB and N‐PEG‐PANI showed conductivity as high as 10² S/cm after treatment with HCl vapor. The photo‐induced conductivity of the N‐PEG‐PANI/PANI‐EB/PAG composite reached 10^?2–10^?1 S/cm. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Conducting polymer coated textile based multilayered shields for suppression of microwave radiations in 8.2–12.4 GHz range

Polypyrrole (PPY) based conducting textiles were prepared by in situ polymerization of pyrrole over cotton fabric. The SEM micrographs show smooth and uniform coating of PPY over fabric with only few loose dendrites. The elemental analysis and XRD patterns revealed the presence of iron whereas magnetization measurement shows ferromagnetic signature with well defined hysteresis loop and saturation magnetization (Ms) of 0.3 emu/g. The good antistatic property and rapid static charge dissipability was reflected by decay profile with decay time of only 0.16 sec. In addition, the microwave absorption studies of multilayered shields; made up of these conducting fabrics; show absorption dominated total shielding effectiveness (SE_T) value of ?43.9 dB (i.e. >99.99% attenuation) which can be attributed to the better impedance matching, high microwave conductivity, shallow skin depth, and multiple scattering of incident electromagnetic radiation. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Structure and electrical properties of grafted polypropylene/graphite nanocomposites prepared by solution intercalation

A novel process was developed to prepare electrically conducting maleic anhydride grafted polypropylene (gPP)/expanded graphite (EG) nanocomposites by solution intercalation. The conducting percolation threshold at room temperature (Φ_c) of the nanocomposites was 0.67 vol %, much lower than that of the conventional conducting composites prepared by melt mixing (Φ_c = 2.96 vol %). When the EG content was 3.90 vol %, the electrical conductivity (σ) of the former reached 2.49 × 10^?3 S/cm, whereas the σ of the latter was only 6.85 × 10^?9 S/cm. The TEM, SEM, and optical microscopy observations confirmed that the significant decrease of Φ_c and the striking increase of σ might be attributable to the formation of an EG/gPP conducting multiple network in the nanocomposites, involving the network composed of particles with a large surface‐to‐volume ratio and several hundred micrometers in size, and the networks composed of the boards or sheets of graphite with high width‐to‐thickness ratio and particles of fine microscale or nanoscale sizes. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 1864–1869, 2003     

Synthesis and characterization of proton conducting polymer electrolyte based on poly(N‐vinyl pyrrolidone)

This work aims at developing and characterizing a proton conducting polymer electrolyte based on Poly(N‐vinyl pyrrolidone) (PVP) doped with ammonium bromide (NH₄Br). Proton conducting polymer electrolytes based on PVP doped NH₄Br in different molar ratios have been prepared by solution casting technique using distilled water as solvent. The XRD pattern confirms the dissociation of salt. The FTIR analysis confirms the complex formation between the polymer and the salt. The conductivity analysis shows that the polymer electrolyte with 25 mol % NH₄Br has the highest conductivity equal to 1.06 × 10^?3 S cm^?1 at room temperature. Also it has been observed that the activation energy evaluated from the Arrhenius plot is low (0.50 eV) for 25 mol % NH₄Br doped polymer electrolyte. The influence of salt concentration on dc conductivity and activation energy of the polymer electrolyte has been discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Synthesis and characterization of water‐soluble conducting polyaniline by enzyme catalysis

Enzymatic synthesis of a water‐soluble, conducting polyaniline (PANI) was studied, using horseradish peroxidase as the biocatalyst and H₂O₂ as the initiator, in the presence of a poly(vinylsulfonic acid, sodium salt) (PVS) polyanion template. The effects of the buffer, concentration of H₂O₂, and the molar ratio of aniline to PVS on the polymerization were particularly investigated. The products were characterized by UV–vis/near‐IR and FTIR spectroscopy, thermogravimetric analysis, and four‐point probe conductivity measurement. The results showed that PVS could be chosen as a new template in the synthesis of PANI. The proper conditions of polymerization were obtained as follows: pH of the buffer was pH 4.0–5.0, the concentration of H₂O₂ was around 20 mM, and the molar ratio of PVS to aniline was 1–1.5. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 814–817, 2005     

Synthesis and characterization of conducting homopolymers and copolymers of o‐anisidine and o‐toluidine in inorganic and organic supporting electrolytes

The influence of inorganic and organic supporting electrolytes on the electrochemical, optical, and conducting properties of poly(o‐anisidine), poly(o‐toluidine), and poly(o‐anisidine‐co‐o‐toluidine) thin films was investigated. Homopolymer and copolymer thin films were synthesized electrochemically, under cyclic voltammetry conditions, in aqueous solutions of inorganic acids (H₂SO₄, HCl, HNO₃, H₃PO₄, and HClO₄) and organic acids (benzoic acid, cinnamic acid, oxalic acid, malonic acid, succinic acid, and adipic acid) at room temperature. The films were characterized by cyclic voltammetry, ultraviolet–visible spectroscopy, and conductivity measurements with a four‐probe technique. The ultraviolet–visible spectra were obtained ex situ in dimethyl sulfoxide. The optical absorption spectra indicated that the formation of the conducting emeraldine salt (ES) phase took place in all the inorganic electrolytes used, whereas in organic acid supporting electrolytes, ES formed only with oxalic acid. Moreover, the current density and conductivity of the thin films was greatly affected by the nature and size of the anion present in the electrolyte. For the copolymer, the conductivity lay between the conductivity of the homopolymers, regardless of the supporting electrolyte used. The formation of the copolymer was also confirmed with differential scanning colorimetry. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2634–2642, 2003     

Structural and thermal characterization of poly(2‐chloroaniline)/red mud nanocomposite materials

We report the synthesis and characterization of a series of conducting poly(2‐chloroaniline) (P2ClAn)/red mud (RM) nanocomposite materials. The polymerization of 2‐chloroaniline in an aqueous medium in the presence of (NH₄)₂S₂O₈ and RM resulted in the formation of a nanocomposite (P2ClAn/RM). The extent of P2ClAn loading in the composites increased with increasing oxidant and monomer concentrations but decreased with RM. The properties of the nanocomposites were characterized with Fourier transform infrared (FTIR), ultraviolet–visible (UV–vis), conductivity measurements, scanning electron microscopy, thermogravimetric analysis, and differential scanning calorimetry analysis. The inclusion of P2ClAn in the composites was confirmed by FTIR studies. The UV–vis spectra of P2ClAn/RM nanocomposites were similar to that of P2ClAn. The conductivity changed in all the composites prepared under various conditions. Thermogravimetric analyses revealed the enhanced thermal stabilities of the nanocomposites with respect to P2ClAn. Morphological images of the as‐synthesized materials were also investigated with scanning electron microscopy and environmental scanning electron microscopy. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006     

Laccase‐catalyzed synthesis of conducting polyaniline‐lignosulfonate composite

Enzymatic polymerization of aniline was first performed in lignosulfonate (LGS) template system. High‐redox‐potential catalyst laccase, isolated from Aspergillus, was used as a biocatalyst in the synthesis of conducting polyaniline/lignosulfonate (PANI‐ES‐LGS) complex using atmospheric oxygen as the oxidizing agent. The linear templates (LGS), also serving as the dopants, could facilitate the directional alignment of the monomer and improve the solubility of the conducting polymer. The process of the polymerization was monitored using UV‐Vis spectroscopy, by which the conditions for laccase‐catalyzed synthesis of PANI‐ES‐LGS complex were also optimized. The structure characterizations and solubility of the complex were carried out using corresponding characterization techniques respectively. The PANI‐ES‐LGS suspensions obtained was used as coating for cotton with a conventional padder to explore the applications of the complex. The variable optoelectronic properties of the coated cotton were confirmed by cyclic voltammetry and color strength test. The molecular weight changes of LGS treated by laccase were also studied to discuss the mechanism of laccase catalyzed aniline polymerization in LGS template system. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 42941.     

Preparation of conducting composites of polypyrrole using supercritical carbon dioxide

Supercritical carbon dioxide, saturated with pyrrole, was brought into contact with oxidant‐impregnated films of poly(chlorotrifluoroethylene) (PCTFE), crosslinked poly(dimethylsiloxane) (PDMS), poly(methyl methacrylate) (PMMA), and porous crosslinked polystyrene (PS) in order to form conducting composites via the in situ polymerization of pyrrole. The two nonporous hosts—PCTFE and crosslinked PDMS—did not form conducting composites with polypyrrole (PPy). On the other hand, the electrical conductivity of the PPy composites with carbon dioxide‐swollen PMMA and porous PS ranged from 1.0 × 10^?4 S/cm to 3.0 × 10^?5 S/cm. In these two cases, the level of pyrrole polymerized on the surface or in the pores of the host polymer was sufficient to attain the interconnected conducting polymer networks necessary for electrical conductivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1113–1116, 2003     

Simultaneous novel synthesis of conducting,nonconducting, and crosslinked polymers by microwave initiation

A novel synthesis of poly(dibromophenylene oxide) (P), conducting polymer (CP), and/or crosslinked polymer (CLP), and/or radical ion polymers (RIP) was achieved simultaneously from sodium 2,4,6‐tribromophenolate by microwave energy in a very short‐time interval. The synthesized polymers were characterized via elemental analysis, FTIR, ¹H NMR and ¹³C NMR, X‐ray diffraction spectroscopy, SEM, DSC, TGA, ESR, GPC, conductivity measurement, and light scattering. It was found that polymerization proceeds through both 1,2‐ and 1,4‐addition at equal rates. The effects of the energy and time on the % conversion and the polymer synthesis were investigated. The optimum condition for synthesis of P (the highest M_w, 2.97 × 10⁵ g/mol) and CP was 70 W for 5 min in 5 mL water and 100 W for 1 min in 0.5 mL water, having maximum values 23.6% and 27.2%, respectively. In addition, synthesis of CLP and RIP were achieved in 5 mL water at 350 W and 700 W at the end of 1 min, respectively. The direct synthesis of highly conducting polymer, with the conductivity of 1 S cm^?2 was achieved in the absence of applied doping process in a very short time sequence. P, CP, CLP, and RIP had fine granular, sponge‐like, dendrite, and coarse surface structures, respectively. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:5427–5435, 2006     

Improvement of conductivity of electrochemically synthesized polyaniline

The electrochemical polymerization of aqueous solution of aniline and HCl was carried out in a single compartment electrochemical cell. After 2 h of the polymerization reaction, polarity of the electrodes was reversed and kept for 1 h. By this process the conductivity of the polyaniline (PAni) formed was found to increase dramatically from 1.1 × 10^?4 to 3.0 × 10^?1 S/cm. The PAni samples obtained both by reversing the polarity (“PANI‐R”) and without reversing the polarity (“PANI”) were characterized by the infrared spectroscopy (FT‐IR), thermogravimetric analysis (TGA), ultraviolet spectroscopy (UV), Hall effect experiment, X‐ray analysis (XRD) and scanning electron microscope (SEM). The results show that the increase in the conductivity of PAni through the reversion of polarity is due to the partial reduction of over oxidized sample giving more emeraldine base and hence more polaron formation with increased charge carrier density and its mobility. The degree of crystallinity and the crystallite size is decreased marginally and the d‐spacing is increased marginally due to this reduction. The PAni behaves like a p‐type semiconductor that means the majority current carriers are holes. A plausible reduction mechanism due to reversal of polarity during electrochemical polymerization is also proposed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2008     

Semiconductive poly[N1,N4‐bis(thiophen‐2‐ylmethylene)benzene‐1,4‐diamine]‐nickel oxide nanocomposite based ethanol sensor

This study aims to use the conductivity of a synthetic polymer as the sensing probe for ethanol. In order to enhance the sensitivity of the sensor, a composite of the polymer and nickel oxide (NiO) nanoparticles was formed as it improved the conductivity. This composite exhibited 100 times more conductivity than the neat polymer. The semiconductive nanocomposite of poly [N¹,N⁴‐bis(thiophen‐2‐ylmethylene)benzene‐1,4‐diamine]‐nickel oxide (PBTMBDA‐NiO) was prepared by in situ chemical oxidative polymerization. The monomer was N¹,N⁴‐bis(thiophen‐2‐ylmethylene)benzene‐1,4‐diamine (BTMBDA). The monomer (BTMBDA), polymer (PBTMBDA), and NiO nanoparticles used in this study were synthesized. The monomer was prepared by refluxing together 2‐thiophene carboxaldehyde, benzene‐1,4‐diamine, and few drops of glacial acetic acid in ethanol medium for 3 h. The polymer, PBTMBDA, was formed by the chemical oxidative polymerization of BTMBDA in chloroform by FeCl₃. NiO nanoparticles were prepared by slow addition of aqueous ammonia to anhydrous nickel chloride at room temperature (28 ± 2 °C), and at a pH of 8 under constant stirring condition. The composite was formed by in situ chemical oxidative polymerization of BTMBDA in chloroform by FeCl₃ in the presence of the dispersed NiO nanoparticles. The molecular structure of BTMBDA and PBTMBDA were confirmed by nuclear magnetic resonance (NMR) (¹H, ¹³C, and Dept‐90°), Fourier transform infrared spectroscopy, and ultraviolet (UV)–visible spectroscopy. The PBTMBDA and PBTMBDA‐NiO nanocomposite were characterized by X‐ray diffraction, thermogravimetric analysis, field emission scanning electron microscopy, and energy‐dispersive X‐ray spectroscopy analysis. The results of characterization studies indicate the strong interaction between PBTMBDA and NiO in the nanocomposite. The broadness of ¹H NMR peaks in PBTMBDA was due to the increased number of monomer units. The disappearance of the peak of α‐hydrogens on thiophene confirms the polymerization involving the fifth position of thiophene part of BTMBDA. The Fourier transform infrared spectroscopy spectra revealed that position of the characteristic peaks of the functional groups in the monomer shifted toward lower wave numbers in PBTMBDA and PBTMBDA‐NiO nanocomposite. This shifting confirms the presence of extended conjugation along the polymer backbone. Electronic spectra of these compounds showed three absorption bands corresponding to π→π*, n→π* and n→π* transitions of π electron of carbon, lone pair electrons of S, and lone pair electrons of N (imine) groups, respectively. From the Tafel plot, the exchange current density evaluated for the BTMBDA and PBTMBDA are 0.2815 × 10⁻⁸ and 1.1508 × 10⁻⁸ A cm⁻², respectively. PBTMBDA is evaluated to be a better electrode material than the BTMBDA. The X‐ray diffraction plots showed that the characteristic peak of NiO in PBTMBDA‐NiO nanocomposite suggested successful incorporation of NiO in PBTMBDA‐NiO nanocomposite. The thermogravimetric analysis revealed the improved thermal stability of the composite. Field emission scanning electron microscopy and energy‐dispersive X‐ray spectroscopy analysis confirmed the presence of the NiO in the composite. Incorporation of nickel oxide nanoparticles improved the electrical conductivity and stability of PBTMBDA. The conductivity of the polymer was found to be of the order of 10⁻⁵ S cm⁻¹ while that of the composite was of the order of 10⁻³ S cm⁻¹. The nanocomposite was found to be thermally more stable than PBTMBDA and exhibited better direct‐current electrical conductivity and isothermal stability than the PBTMBDA as revealed by the four‐probe study. The electrical conductivity as inferred from the four‐probe method was used as the parameter to study the isothermal stability of the composite. The PBTMBDA‐NiO nanocomposite based vapor sensor was constructed for the sensing of ethanol vapor in commercial ethanol and real samples (alcoholic drinks: Beer, Wine, Brandy, Vodka, Whisky, and Rum) It was observed that on exposure to ethanol vapor at ambient temperature, the electrical resistivity of the nanocomposite increased indicating suppression of charge carriers. The interaction of ethanol vapor with PBTMBDA in PBTMBDA‐NiO nanocomposite was confirmed by IR spectral technique. The change in the structure of the PBTMBDA on interaction with ethanol was highlighted by the changes in the infrared spectrum. The conductivity of the polymer was explained using the structure‐activity relationship of the monomer evaluated using Gaussian 09 software. This study also analyzed the total electron density with electrostatic potential of the monomer and its correlation with chemical reactivity in order to explain the ethanol vapor sensing‐property of the nanocomposite. A new method of ethanol vapor sensing by a conducting polymer composite is hereby reported. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45918.     

Boron nitride based polyaniline nanocomposite: Preparation,property, and application

In this study, we report first time the electrical properties and photocatalytic activity of HCl doped polyaniline (Pani) and Pani/boron nitride (Pani/BN) nanocomposite prepared by in situ polymerization of aniline using potassium persulfate (K₂S₂O₈) in the presence of hexagonal boron nitride (h‐BN). The prepared Pani and Pani/BN nanocomposite were characterized by Fourier transform infrared, X‐ray diffraction, Thermogravimetric analysis, Scanning electron microscope, and Transmission electron microscope. The stability of the Pani/BN nanocomposite in comparison of Pani in terms of the DC electrical conductivity retention was investigated under isothermal and cyclic aging conditions. The Pani/BN nanocomposite in terms of DC electrical conductivity was observed to be comparatively more thermally stable than Pani. The degradation of Methylene blue (MB) and Rhodamine B (RhB) under UV‐light irradiation were 50 and 56.4%, respectively, over Pani and 65.7 and 71.6%, respectively, over Pani/BN. The results indicated that the extent of degradation of MB and RhB was greater over nanocomposite material than Pani, which may result due to high electron–hole pairs charge separation under UV light. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43989.     

Improvement of the conductivity,electroactivity, and redoxability of polythiophene by electropolymerization of thiophene in the presence of catalytic amount of 1‐(2‐pyrrolyl)‐2‐(2‐thienyl) ethylene (PTE)

The electropolymerization of thiophene in the presence of 1‐(2‐pyrrolyl)‐2‐(2‐thienyl) ethylene (PTE) was investigated. PTE was synthesized via Wittig reaction and by the addition of catalytic amount of PTE during the electropolymerization of thiophene, the conditions of electropolymerization of thiophene were modified. The cyclic votammograms of polythiophenes (PThs) in different conditions were obtained. The analysis of cyclic votammograms of PThs shows a considerable increase in the electroactivity and redoxability when the electropolymerization of thiophene in the presence of catalytic amount of PTE was performed. The presence of PTE during electropolymerization of thiophene leads to an increase in the rate of polymerization too. The cyclic voltammetry (CV) measurement of electron transfer ferro/ferricyanide redox system on different modified glassy carbon (GC) electrode has shown that the rate of charge transfer for PTh in the presence of PTE increased in comparison to pure PTh. The conductivity of obtained polymers was determined by electrochemical impedance spectroscopy (EIS) technique in 3.5% (w/v) NaCl solutions. The Zview(II) software was applied to the EIS to estimate the parameters of the proposed equivalent circuit, based on a physical model for the electrochemical behavior of coatings on GC. The R_ct value obtained for PTh is 7667 Ω cm². This value decreases in the presence of PTE to 4437 Ω cm². Thus, the new film has more conductivity. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Synthesis and characterization of a conducting polyaniline/TiO2−SiO2 composites

Polyaniline/TiO₂?SiO₂ composites were prepared by an in situ chemical oxidation polymerization approach in the presence of hybrid TiO₂?SiO₂ fillers. The obtained polyaniline/TiO₂?SiO₂ composites were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FTIR), X‐ray diffraction (XRD), thermogravimetry (TG), and current?voltage (I?V) measurements. SEM picture shows a variation in morphology of polyaniline (PANI) from fiber shape to relatively regular particle shape with increasing TiO₂?SiO₂ contents in the composites. The floccule‐like structures were observed by high resolution TEM, which may help improve the efficiency of conductive network. SEM, XRD, TG, and FTIR spectra all reveal that a relatively strong interaction exist between TiO₂?SiO₂ and PANI. The I?V characteristics in such composites indicate that the charge transport is mainly governed by the space charge effects, which occurs at the interface between the conducting PANI and TiO₂?SiO₂. Meanwhile, PANI/TiO₂?SiO₂ composites exhibit significant increase in conductivity than PANI/TiO₂ or PANI/SiO₂. The reasons about high conductivity of PANI/TiO₂?SiO₂ have also been discussed. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2288–2295, 2013     

Characterization and physical properties investigation of conducting polypyrrole/TiO2 nanocomposites prepared through a one‐step “in situ” polymerization method

Nowadays, nanocomposites are a special class of materials having unique physical properties and wide application potential in diverse areas. The present research work describes an efficient method for synthesis of a series of polypyrrole/titanium dioxide (PPy/TiO₂) nanocomposites with different TiO₂ ratios. These nanocomposites were prepared by one‐step in situ deposition oxidative polymerization of pyrrole hydrochloride using ferric chloride (FeCl₃) as an oxidant in the presence of ultra fine grade powder of anatase TiO₂ nanoparticles cooled in an ice bath. The obtained nanocomposites were characterized by Fourier‐transform infrared (FTIR), thermogravimetric analysis (TGA), X‐ray diffraction (XRD), and scanning electron microscope (SEM) techniques. The obtained results showed that TiO₂ nanoparticles have been encapsulated by PPy with a strong effect on the morphology of PPy/TiO₂ nanocomposites. Also, the synthesized PPy/TiO₂ nanocomposites had higher thermal stability than that of pure PPy. The investigation of electrical conductivity of nanocomposites by four‐point probe instrument showed that the conductivity of nanocomposite at low TiO₂ content is much higher than of neat PPy, while with the increasing contents of TiO₂, the conductivity decreases. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012