PANI), Polypyrrole Research Articles

Polyaniline–polypyrrole nanograined composite via electrostatic adsorption for high performance electrochemical supercapacitors

We demonstrate a novel approach for the preparation of layered Polyaniline–polypyrrole (PANI–PPy) nanocomposite via simplest oxidative chemical polymerization. The approach is conceptualized on the basis of the electrostatic interactions between cationic source (aniline/pyrrole with H2SO4) and anionic source (ammonium persulfate) in double distilled water. The investigation describes advantages of facile successive ionic layer adsorption and reaction (SILAR) for depositing nanograined PANI–PPy thin film onto cost-effective large area stainless steel substrates. The physico-chemical characteristics of deposited films are studied via analysis of structural, morphological, surface wettability and Brunauer–Emmett–Teller (BET) analysis. A PANI–PPy nanocomposite prepared from this approach exhibited an excellent electro-capacitive performance with a high specific capacitance over 737F/g at 5mVs−1 scan rate. Impedance measurements suggest that the nanograined PANI–PPy electrodes are promising for the next generation high performance electrochemical supercapacitors. The simple method described here opens up a generalized route to make a wide range of PANI–PPy based nanocomposite materials for applications beyond electrochemical energy storage.

Preparation and electromagnetic properties of Polyaniline(polypyrrole)-BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite nanocomposites

The nanocomposite of hard (BaFe12O19)/soft ferrite (Ni0.8Zn0.2 Fe2O4) was prepared by the sol–gel process, and then the polyaniline(PANI)/polypyrrole(PPY)-BaFe12O19/Ni0.8Zn0.2Fe2O4 was produced by in situ polymerization method. The structures, morphology and electromagnetic properties of the samples were characterized by various instruments. XRD, TEM, and FTIR analysis indicated that BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite were homogenously enwrapped by PANI(PPY) coating. The VSM and SDY-4 measurement show that the magnetic properties of the composites decreased with the increase in PANI(PPY) amount, However, the electrical conductivity is on the contrary. The electromagnetic properties of the composites were much better than BaFe12O19/Ni0.8Zn0.2Fe2O4 in the frequency range of 2–15GHz, which mainly depends on the dielectric loss of PANI(PPY). A minimum reflection loss of the PANI(PPY)-BaFe12O19/Ni0.8Zn0.2Fe2O4 ferrite nanocomposite is −19.7dB(−21.5dB) at the frequency of 7.3GHz (10.7GHz).

Conjugate Polymer-Supported Acid Catalysts: An Efficient and Reusable Catalyst for the Synthesis of Geminal Diacetates (Acylals) Under Solvent-Free Conditions

A comparative study on the catalytic activity of conducting polyaniline (PANI), polypyrrole (PPY), and poly-(3,4-ethylenedioxythiophene) (PEDOT) salts as solid acid catalysts for the synthesis of 1,1-diacetates (acylals) under solvent-free conditions has been presented. Use of the polypyrrole and poly-(3,4-ethylenedioxythiophene) salts as solid acid catalysts is reported for the first time. Preparation, recovery, and reusability of the catalysts were found to be good.

Electrosynthesis and capacitive performance of polyaniline–polypyrrole composite

AbstractThe composite of polyaniline and polypyrrole (PPY‐PANI) was prepared by two‐step electrochemical polymerization method. Techniques of scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), and thermal gravity analysis (TG/DTG) measurements were used to characterize the morphology and structure of the composite. The electrochemical properties of the composite were investigated by cyclic voltammetry (CV), galvanostatic charge‐discharge, and electrochemical impedance spectroscopy (EIS). The results indicated that the polyaniline–polypyrrole composite showed better electrochemical capacitive performance than polypyrrole (PPY) and polyaniline (PANI). The specific capacitance of the composite electrode was 523 F/g at a current of 6 mA/cm2 in 0.5 M H2SO4 electrolyte. POLYM. COMPOS., 2011. © 2010 Society of Plastics Engineers

Fabrication of Chemiluminescence Sensor Based on Conducting Polymer@SiO2/Nafion Composite Film

Tris(2,2'-bipyridyl)ruthenium (II) (Ru(bpy)2+) electrogerated chemiluminescence (ECL) sensor was fabricated by immobilization of Ru(bpy)2+ complex on conducting polymer@SiO2/Nafion composite film on surface of glassy carbon electrode. The conducting polymer@SiO2 nanocomposites were prepared by coating polyaniline (PANI), polypyrrole (PPy), and polythiophene (PTh) on the surface of the SiO2 sphere. The conducting polymer@SiO2 nanocomposite was characterized by scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and atomic force microscopy (AFM). The sensitivity and reproducibility of the prepared ECL sensor to tripropylamine (TPA) was evaluated. As a result, the PPy@SiO2 composite electrode exhibited high sensitivity and good reproducibility compared to that obtained with PANI@SiO2 and PTh@SiO2 composite electrodes because of the strong interaction between PPy@SiO2 and Ru(bpy)2+ complex.

Preparation of one-dimensional (1D) polyaniline–polypyrrole coaxial nanofibers and their application in gas sensor

A facile and low-cost method has been developed to prepare one-dimensional (1D) polyaniline–polypyrrole (PANI–PPy) coaxial nanofibers (PPCF). The morphology and molecular structure of PPCF were proved by scanning electron microscopy, transmission electron microscopy, EDX, UV–vis, FTIR and Raman spectroscopy. A possible synthetic scheme for the synthesis of PPCF has been proposed. The electrical responses of PPCF to triethylamine (TEA) vapor were measured at room temperature. It was found that PPCF showed a rapid, sensitive and reversible conductance change upon exposure to TEA vapor at concentrations ranging from 1 to 1000 ppm. The results suggested that the comprehensive performance of the gas sensor using PPCF was better than the results obtained using PANI nanofibers and PPy separately. In addition, a sensing mechanism was proposed.

Thermal Degradation Studies on Polyaniline–Polypyrrole Copolymers Prepared by Microemulsion Methods

Solvent- and water-based microemulsions of aniline and pyrrole copolymers were synthesized, and the thermal degradation properties of the copolymers were studied. The morphology of the copolymers prepared using solvent-based microemulsions containing 80 % aniline in the feed showed highly oriented, crystalline, ordered long nano-fibers which were even more structured than that of pure aniline prepared by the same method. The influence of the degree of crystallinity calculated from X-ray diffraction and morphology had an overlap with thermal degradation and activation energies of different transitions. Copolymers prepared with water-based microemulsions were thermally less stable than the ones prepared using solvent-based microemulsions. The concentration of pyrrole and aniline mutually influenced the thermal properties of the copolymers.

Studies on polyaniline–polypyrrole copolymer micro emulsions

Solvent and water based micro emulsions of the aniline and pyrrole copolymers were synthesized and the properties of the copolymers were studied. The morphology of the copolymers prepared from the solvent based micro emulsions containing 80% aniline in the feed shows highly oriented and ordered long sub micro fibers which is more structured even that of pure aniline prepared by the same method. While polypyrrole prepared from solvent based micro emulsions show highly uniform granules of uniform shape and size. Polypyrroles prepared from water based micro emulsions show more sub micro fibrous structures of short length and diameter apart from having granules of sub micro dimensions. Cauliflower like hyper branched morphology was obtained for copolymers prepared from water based micro emulsions with sub micro dimensions. The dimensions of the above were confirmed by the data obtained from XRD like lateral order, lamellar thickness, etc. The concentration of pyrrole and aniline mutually influence the properties like conductivity and viscosity of copolymer emulsions, which were influenced by the orientation and order.

Highly Conductive Polyfuran-13X Zeolite-Polyaniline Composite

During the last few decades, polymer based hybrid organicinorganic composite materials have attracted a considerable research attention all over the world due to their extraordinary properties, which comes out of the synergism of distinctive properties of the components. 1,2 While the incorporation of inorganic silicates (e.g., zeolites) as reinforcing fillers into various polymeric organic matrixes (e.g., elastomers) has been proved to be an efficient way of improving several properties of the resulting composite materials, 1,3 the emergence of organic conducting polymers in the field has opened a novel and very important means to prepare advanced organic-inorganic functional materials. 4,5 Among several � -conjugated conducting polymers (CPs), polyacetylene (PA), polyaniline (PANI), polypyrrole (PPY), and polythiophene (PTP) based composite materials have received a great deal of interest due to their high electrical conductivity and chemical and environmental stability. 1,5–11 Significantly, CPs-based materials are being used these days as ‘plastic electronics’ 11–14 (light emitting diodes (LEDs), photovoltaics, field-effect transistors (FETs)) and ‘smart fluids’ 15,16 (usually called electrorheological fluids (ERFs) which are suspensions of polarizable particles dispersed in an insulating matrix). However, owing to difficulty in synthesizing a regular � conjugated structure with high conductivity, polyfuran (PF) has attracted relatively less attention. It is reported that PF exhibits some distinctive properties such as electrochromic effect and good redox ability. 17 Moreover the resource of furan (F) is much greater and thus F is much less expensive than its N and S analogues pyrrole (PY) and thiophene (TP) respectively. These characteristics should attract the attention of more scientists in chemistry and materials science. In the past decades, the electrochemical synthesis and properties of PF, co-PF-PPY, coPF-PTP biopolymer films have been studied. 18–20 But it is observed that due to high oxidation potential of F, a significant cleavage of the ring generally occurred during the electropolymerization, hence, strongly breaking the expected � conjugated structure. The polymer obtained is dielectric or very low electrically conductive and the yield of the PF formed was greatly restricted by the area of the electrode used. Therefore, a chemical oxidative polymerization (COP) is needed. Recently Li et al. 21 developed a combinatorial approach to synthesize PF and co-PF-PANI composite via COP with variable electrical

Preparation of polyaniline–polypyrrole composite sub‐micro fibers via interfacial polymerization

AbstractPolyaniline–polypyrrole (PANI–PPy) composite sub‐micro fibers were prepared via interfacial polymerization of aniline and pyrrole using ammonium persulfate (APS) as oxidant. Carbon tetrachloride was used as the organic solvent to dissolve the monomers and APS was dissolved in HCl aqueous solution. The reaction was carried out at the interface formed by the two above solutions. Scanning electron microscopy, Fourier transformation infrared spectra and differential thermal analysis were conducted to characterize the morphology, structure and thermostability of the resulting composites. Dodecyl benzene sulfonic acid was also used as medium to make comparison with that using HCl in the reaction system. The guidance of the formation of the PANI nanofibers at the first step and the interaction between PANI and PPy were considered as the drive forces to yield the composite sub‐micro fibers. POLYM. COMPOS., 29:22–26, 2008. © 2007 Society of Plastics Engineers

A comparative study on electrochemical co-deposition and capacitance of composite films of conducting polymers and carbon nanotubes

Composite films of carbon nanotubes (CNTs) with polyaniline (PANI), polypyrrole (PPY) or poly[3,4-ethylenedioxythiophene] (PEDOT) were prepared via electrochemical co-deposition from solutions containing acid treated CNTs and the corresponding monomer. In the cases of PPY and PEDOT, CNTs served as the charge carriers during electro-deposition, and also acted as both the backbone of a three-dimensional micro- and nano-porous structure and the effective charge-balancing dopant within the polymer. All the composites showed improved mechanical integrity, higher electronic and ionic conductivity (even when the polymer was reduced), and exhibited larger electrode specific capacitance than the polymer alone. Under similar conditions, the capacitance was enhanced significantly in as-prepared PPY-CNT and PEDOT-CNT films. However, the fresh PANI-CNT film was electrochemically similar to PANI, but PPY-CNT and PEDOT-CNT differed noticeably from the respective polymers alone. In continuous potential cycling tests, unlike the pure polymer and other composite films, PANI-CNT performed much better in retaining the capacitance of the as-prepared film, and the possible cause is analysed.

Inverse conjugated polymer opals and their luminescent spectra

Colloidal silica spheres are usually used for making opal photonic crystals. With the aim to create tunable or otherwise functional opals we have coated colloidal SiO2 spheres with conjugated polymers, including: polyaniline sulfonic acid, polypyrrole and MEH-PPV (poly [2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene]). Spheres coated with MEH-PPV were dispersed in H2O and coated with polyelectrolytes that charged the colloidal surfaces allowing the polymer coated spheres to self-assemble by sedimentation under gravity into close packed structures with well ordered crystalline domains. Inverse MEH-PPV/polypropylene photonic crystals were fabricated and their photoluminescence was blue shifted compared to a uniform MEH-PPV film.

Preparation and characterization of polyaniline–polypyrrole composite from polyaniline dispersions

AbstractPolyaniline–polypyrrole (PANI‐PPy) composite was prepared by in situ polymerization of pyrrole in PANI dispersion using FeCl3·6H2O as oxidant and sodium dodecyl benzene sulfonate (SDBS) as surfactant. Different synthesis conditions of PANI dispersion including the relative concentration of aniline and SDBS and the amount of acid (HCl) on the morphology and conductivity of the resulting composites were investigated. Fourier transformation infrared (FTIR) spectra, X‐ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), X‐ray diffraction (XRD) patterns, and contact angles of the composites showed there existed certain interaction between PANI (or PANI‐SDBS) and PPy. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3523–3529, 2007

Hydrogen evolution on conducting polymer electrodes in acidic media

Hydrogen evolution reaction (HER) was studied on polyaniline (PAn), polypyrrole (PPy) and on aniline/pyrrole (PAn–PPy) copolymer in acidic solutions. The cathodic Tafel slopes ( b c) and exchange current densities ( j 0) were calculated from Tafel curves obtained in solutions of X M H 2SO 4 ( X = 0.1, 0.2, 0.3, 0.4 and 0.5 M). Activation energies ( E a) were determined. The E a-values were found to be ca. 26 for PAn, 36.5 for PPy, 40.6 for PAn–PPy and 20.6 kJ mol −1for Pt.

Organic Coatings On Metal Surfaces ForCorrosion Protection

Polyaniline–polypyrrole composite coatings were formed on platinum and titanium substrates by galvanostatic electrochemical polymerisation. Electropolymerisation was done by varying the applied current and molar feed ratio of monomers. It was shown that the structure, yield and the morphology of the coatings were dependent on the feed ratio of monomers (aniline and pyrrole) and the applied current or potential. As the oxidation potential of aniline and pyrrole are very similar, we believe that simultaneous oxidation and codeposition of polyaniline and polypyrrole is possible by changing the applied potential. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical properties of the resulting composites.

Supercapacitors based on conducting polymers/nanotubes composites

Three types of electrically conducting polymers (ECPs), i.e. polyaniline (PANI), polypyrrole (PPy) and poly-(3,4-ethylenedioxythiophene) (PEDOT) have been tested as supercapacitor electrode materials in the form of composites with multiwalled carbon nanotubes (CNTs). The energy storage in such a type of composite combines an electrostatic attraction as well as quick faradaic processes called pseudo-capacitance. It has been shown that carbon nanotubes play the role of a perfect backbone for a homogenous distribution of ECP in the composite. It is well known that pure conducting polymers are mechanically weak, hence, the carbon nanotubes preserve the ECP active material from mechanical changes (shrinkage and breaking) during long cycling. Apart of excellent conducting and mechanical properties, the presence of nanotubes improves also the charge transfer that enables a high charge/discharge rate. For an optimal use of ECPs in electrochemical capacitors, a special electrode composition with ca. 20 wt.% of CNTs and a careful selection of the potential range is necessary. The capacitance values ranging from 100 to 330 F g −1 could be reached for different asymmetric configurations with a capacitor voltage from 0.6 to 1.8 V. It is also noteworthy that such a type of ECP/CNTs composite does not need any binding substance that is an important practical advantage.

Conductive copolymers of polyaniline, polypyrrole and poly(dimethylsiloxane)

Two step electrochemical polymerization method was used to obtain various conductive homopolymers, composites and copolymers of Polyaniline (PAn), Polypyrrole (PPy) and Poly(dimethylsiloxane) (PDMS). PAn/PPy, PDMS/PAn/PPy, PPy/PAn and PDMS/PPy/PAn conductive polymer films were synthesized with different compositions and their properties were compared. Films were characterized by conductivity measurements, cyclic voltammetry (CV), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) techniques. When both PPy and PAn existed in the films, the major contribution to the conductivity was due to the PPy component. PDMS/PPy/PAn films were more conductive than PDMS/PAn/PPy films similar to their binary counterparts without PDMS. When PPy was coated over PAn, thermally more stable films were obtained than the films synthesized in reverse order. The characterization tests implied the formation of chemically bounded new structures such as crosslinking copolymer structures. SEM microphotographs of PDMS/PAn/PPy films indicated a clear double layer structure. Hence, changing the order of coating had significant effects on the structure and properties of films.

The catalytic activity of conducting polymers toward oxygen reduction

The reduction of oxygen at electronically conducting polymers (ECPs) such as polyaniline (PANI), polypyrrole (PPy), polythiophen (PTh), and poly(3-methyl)thiophen (PMeT), poly(3,4-ethylenedioxythiophene) (PEDOT) have been studied. The electrochemical investigations of ECPs based catalytic electrodes in oxygen-saturated electrolytes indicate the existence of electrocatalytic activity toward the oxygen reduction at different ECPs with the exception of PEDOT. To explain the reasons of the catalytic activity of ECPs, a quantum-chemical modeling of ECPs and adsorption complexes of ECPs with oxygen have been performed. To calculate the electronic structure of molecular clusters and their complexes with oxygen, the PM 3 program of the MOPAC computer system was used. The catalytic activity takes place due to the unique electronic structure of ECPs. The calculations showed that the bond orders in chemisorbed oxygen molecules at PANI decrease by a third, and the bond length increases by more than 20% in comparison with that in a free oxygen molecule. Thus, chemisorbed oxygen molecules have a fairly high degree of activation and can be readily reduced at the polymeric surface. The similar mechanism takes place on the active carbon atoms of PPy, PTh, and PMeT.

Polyoxometallates as inorganic templates for electrocatalytic network films of ultra-thin conducting polymers and platinum nanoparticles

We develop a concept of fabrication of the multilayer network films on electrodes by exploring the ability of a Keggin-type polyoxometallate, phosphododecamolybdate (PMo 12O 40 3−), to form stable anionic monolayers (templates) on carbon and metals including platinum. By repeated alternate treatments in the solution of PMo 12O 40 3− (or in the colloidal suspension of polyoxometallate-protected Pt-nanoparticles) and in the solution of monomer (e.g. anilinium) cations, the amount of the material can be increased systematically (layer-by-layer) to form stable three-dimensional assemblies on electrode (e.g. glassy carbon) surfaces. In the resulting hybrid (organic–inorganic) films, the layers of negatively charged polyoxometallate, or polyoxometallate-protected (stabilized) Pt-nanoparticles, are linked or electrostatically attracted by ultra-thin layers of such positively charged conducting polymers as polyaniline (PANI), polypyrrole (PPy) or poly(3,4-ethylenedioxythiophene), PEDOT. Consequently, the attractive physicochemical properties of polymers and reactivity of polyoxometallate or noble metal particles are combined. The films are functionalized and show electrocatalytic properties towards reduction of nitrite, bromate, hydrogen peroxide or oxygen. They are of importance to the chemical and biochemical sensing as well as to the biochemical and medical applications.

Electrical and morphological properties of PP and PET conductive polymer fibers

Conductive fibers were obtained using two experimental processes (melt spinning and coating process). In melt spinning process, polyaniline (PANI), polypyrrole (PPy) and graphite were used in order to obtain conductive polypropylene (PP) based fibers with specific electrical and mechanical properties. PANI was treated using dodecylbenzene sulfonic acid (DBSA) to improve the solubility and the dispersion of PANI in xylene. PANI coating on PET yarns were performed by absorption of yarns through PANI solution. The electrical resistance and morphological characteristics of conductive yarns were investigated. These yarns are supposed to be used to create smart clothing, corrosion protection or conductive fabrics for electromagnetic shielding applications.