Characterization Of Polyaniline Research Articles

In situ chemically polymerised polyaniline nanolayer: characterisation and sensing materials

An experiment has been carried out to study the formation and characterisation of polyaniline (PANi) nanolayer growth directly on glass and alumina substrate by in situ chemical polymerisation. It has been found that the growth mode of the PANi nanolayer depends on the synthesis time and mechanical agitation. The difference in growth modes results in the form of granular, planar or fibrillar structure and then affects the chemical and electronic structure of the PANi nanolayer. As a result of gas-PANi chain interaction the resistance of the PANi nanolayer is highly sensitive to a variety of gases in environment such as oxygen (oxidising agent), NH3 (reducing agent) and so forth. The feature enables PANi nanolayer made by in situ chemical polymerisation, a promising candidate for gas sensing materials.

RF-plasma polymerization and characterization of polyaniline

Suitable modifications are done in a RF sputtering set up to facilitate synthesis of polyaniline thin film by RF-plasma polymerization process. The synthesized films are characterized by FTIR, XRD, Ellipsometry, UV–visible absorption & reflection and SEM. The films prepared are highly cross-linked, amorphous in nature and have band gap of 2.07 eV. SEM images show the uniformity in film morphology. The refractive index of the films is determined to be 1.11 and dielectric constant is 1.12 at a wavelength 620 nm in the visible region.

In situ polymerization and characterizations of polyaniline on MWCNT powders and aligned MWCNT films

Polyaniline/CNT composites have been synthesized by means of in situ polymerization on two different macroscopic structures of CNTs, namely non-ordered CNT powders and aligned CNT films supported on Ti foils. SEM, TEM images illustrated that a rather uniform layer of PANI with a thickness of 5–8 nm has been successfully coated on the aligned CNTs. The molecular structure and the degree of protonation of PANI have been studied by means of Raman spectroscopy. The alignment of CNT film on the foils favors the formation of uniformly distributed layer of the protonated PANI on each CNT, which is possibly a result of controlled diffusion in the pseudo 1D channel and a confinement in the space between CNTs in the aligned CNT films. Furthermore, the reaction temperature has a more pronounced effect on the degree of protonation of PANI on the CNT powders than on the aligned CNT films.

The characterization of polyaniline and polypyrrole composites by pyrolysis mass spectrometry

AbstractIn this work, direct insertion probe pyrolysis mass spectrometry technique was applied to investigate the thermal and structural characteristics of electrochemically prepared polyaniline (PANI), polypyrrole (PPy), and their composites/copolymers synthesized either by electrochemical polymerization of pyrrole on PANI‐coated electrode (PANI/PPy) or by coating PANI on PPy (PPy/PANI) in H2SO4 solutions. It has been determined that the polymer first coated on the electrode degraded to a certain extent during the polymerization of the second. The extent of degradation was greater for PPy and increased with the increase in acid concentration. On the other hand, the detection of mixed dimers confirmed copolymer formation. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis and Characterization of Polyaniline -Crooked Gold Nanocomposite with Reduced Conductivity

Conducting Polyaniline (Pani)-crooked Gold nanocomposites were synthesized by in situ chemo-oxidative polymerization of aniline with previously made crooked gold nanoparticles by using ammonium per oxidisulphate as oxidizing agent and p-toluene sulphonic acid (p-TSA) as dopant. The formation of nano gold was established by UV-visible spectroscopy with a SPR peak at 512 nm and crooked morphology was confirmed by TEM. Spectroscopic analysis confirmed the formation of the conducting emeraldine salt phase of the polymer. Due to clustering of composite nanoparticles, the polymer composite formed one-dimensional rod-like morphologies. Thermogravimetric analysis revealed a typical three-step decomposition pattern pertaining to polyaniline emeraldine salt. The conductivity of the nanocomposite was found to be lower (2.47 S/cm) than the virgin p-TSA doped polyaniline (5.55 S/cm).

Synthesis and characterization of polyaniline: nanospheres, nanorods, and nanotubes—catalytic application for sulfoxidation reactions

AbstractThe synthesis of nanostructured polyaniline (PANI) with different morphologies by simple alkali‐guided template‐free method followed by doping them with vanadium has been described. The synthesized polyaniline nanoparticles have been well characterized by various techniques. Further, the catalytic activity of the undoped and doped PANI nanostructures for selective oxidation of sulfides to sulfoxides in water has been studied. It was observed that the special morphology of nanostructures plays an important role in enhancement of catalytic activity. Vanadium‐doped PANI nanotubes and nanorods showed higher activity and selectivity than nanospheres. The catalyst has been reused for five consecutive cycles with consistent activity. Copyright © 2008 John Wiley & Sons, Ltd.

Preparation and characterization of polyaniline with high electrical conductivity

AbstractIn the present paper, polyaniline (PANI) was polymerized by ammonium persulphate using a chemically oxidative process under mild tempertures ranging from −5–20°C. Electrical conductivity of as synthesized PANI got enhanced gradually owing to the increase in molecular weight and crystallinity with decrease in synthesis temperature. Extraction with tetrahydrofuran (THF) was employed as the purification method of emeraldine base (EB) to enhance the electrical conductivity of PANI effectively attributed to the removal of the low molecular weight fractions and defective molecular chains. Methanesulfonic acid (MSA) was used to dope EB due to its strong acidity and small molecular size, and the amount of dopant versus EB was also optimized. Using a novel “synergistic doping” process with m‐cresol, electrical conductivity of PANI is further enhanced owing to more regular molecular chains which resulted in better interchain charge carriers' conduction. The emeraldine salts obtained finally have high electrical conductivity reaching up to 32.5 S cm−1, which is much higher than that of the conventionally synthesized sample reported previously. Copyright © 2008 John Wiley & Sons, Ltd.

Metal−Polymer Composites: Synthesis and Characterization of Polyaniline and Other Polymer@Silver Compositions

A method was developed for the entrapment of water-insoluble hydrophobic polymers in a metallic matrix, thus generalizing further the routes for obtaining the novel organics@metal composite materials. The reaction took place in an organic phase using the reduction of metal ions by DMF in the presence of water. The reductive entrapment of polyaniline was studied in detail using XRD, SEM, BET, TGA, UV−vis, XPS, and density measurements, and the mechanism of the entrapment was established. The scope of this approach is demonstrated by entrapment of two additional hydrophobic polymers, polystyrene and polyacrylonitrile.

Synthesis and characterization of polyaniline in magnetic field

Polyaniline was obtained by chemical oxidation in the microemulsion system consisting of aniline, emulsifier, assistant emulsifier and water in magnetic field (0 T, 0.2 T, 0.4 T, 0.6 T). The effect of magnetic field on the polymerization rate and the inherent viscosity of polyaniline were studied. The molecular structure of polyaniline was characterized by IR spectra and the thermal degradation behavior was assessed using TG techniques. The results show that the polymerization rate, molecular weight, thermal stability and conductivity of the synthesized polyaniline enhanced and no effect on the basic structural units of polyaniline was observed in magnetic field. Within the range of the intensity of magnetic field studied, the magnetic field of 0.4 T exerts the largest influence on polymerization of aniline.

Ac and Dc conductivities of polyaniline/poly vinyl formal blend films

Abstract The synthesis and characterization of polyaniline (PANI)/poly vinyl formal (PVF) blend films were carried out in this work. Polyaniline base was doped using dodecylbenzene sulfonic acid (DBSA). These blend films were characterized by UV–Visible, FTIR spectra and scanning electron microscopy (SEM) to investigate their optical, structural and morphological properties. It was found that the percolation threshold of these blends is 4.4 wt% of PANI. The dc and ac conductivities of these blend films have been measured at a temperature range from 300 to 100 K in the frequency range of 10 kHz to 1 MHz. The electrical conductivity of the blend films enhanced with the increase of polyaniline amount up to a value of 2.5 × 10−4 S cm−1 at 65 wt% of polyaniline. The dc conductivity of the PANI/PVF blend films follows the three-dimension variable range hopping. Temperature variation of frequency exponents in this blend suggests that ac conduction is attributed to be correlated barrier hopping.

Formation of polyaniline layer on DNA by electrochemical polymerization

We report the electropolymerization and characterization of polyaniline (PAN) on both DNA monolayer and single poly(dG)–poly(dC) DNA molecules serving as a template. The synthesis includes the formation of an electrostatic complex between the negatively charged DNA and positively charged anilinium ions followed by electrochemical oxidation and polymerization of the anilinium ions' monomers on the DNA template. The polymerization was carried out on a flame annealed gold substrate modified with positively charged self-assembled 4-aminothiophenol (4-ATPh) monolayer. The resulting monolayers and single macromolecular composites of DNA–PAN were characterized by atomic force microscopy (AFM), cyclic voltammetry (CV) impedance and UV–vis spectroscopy.

Characterization of polyaniline via pyrolysis mass spectrometry

In this work, direct insertion probe pyrolysis mass spectrometry technique was applied to investigate the thermal and the structural characteristics of electrochemically prepared HCl and HNO3-doped polyaniline (PANI) films. It has been determined that the thermal degradation of both samples showed three main thermal degradation stages. The first stage around 50–60°C was associated with evolution of solvent and low-molecular-weight species adsorbed on the polymer, the second stage just above 150°C was attributed to evolution of dopant-based products, and the final degradation stage at moderate and elevated temperatures was associated with evolution of degradation products of the polymer. Chlorination and nitrolysis of aniline during the electrochemical polymerization were detected. Extent of substitution increased as the electrolysis period was increased. Furthermore, for the HNO3-doped PANI, the evolution of CO2 at elevated temperatures confirmed oxidation of the polymer film during electrolysis. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of D.C. Voltages Using HCl for the Synthesis and Characterization of Polyaniline

This study is related to the electrochemical polymerisation of aniline in the presence of hydrochloric acid at DC voltages from 1.1 V to 2.1 V with platinum, stainless steel electrodes of uniform cross section. 1 M of acid and 0.1 M of monomer are taken. Efforts are concentrated on the importance of polyaniline deposited on the working electrode and the collection of pure samples out of it from forty trials each. Each trial runs for one hour. Double distilled water is used for the filtering of polyaniline. Due to the presence of mono basic acid, the FTIR peaks are well defined and their presence indicates the definite vibrational modes of the elements. The acid affects the polymerization of aniline and the results are in reasonable agreement with earlier reports. At 1.7 V the conductivity is well exhibited by HCl doped PANI. It is found that the applied DC voltage plays a role on the synthesis of polyaniline using HCl.

Preparation, degradation of polyaniline doped with organic phosphorus acids and corrosion essays of polyaniline–acrylic blends

Preparation and characterization of polyaniline (PANI) doped with anions containing phosphorus was investigated with the help of various technique. The chemical polymerization of aniline was carried out in acid media containing different anions of organic phosphorus acid with the use of ammonium peroxidisulfate as oxidant agent. The highest yield was observed in the case of styrilphosphonic acid. The conductivity increased in the following order: phenylphosphinic acid < 2chloroethylphosphonic acid < styrilphosphonic acid. The solubility tests carried out in DMF, DMSO and NMP showed that the presence of voluminous anions improves the solubility of doped PANI. The synthesized PANI was characterized by density, intrinsic viscosity, solubility, FTIR, UV–vis, NMR, conductivity and TGA measurements. The hardness, elasticity, resistance and protective behavior of acrylic films were determined. The acrylic dispersion based on PANI doped with anions containing phosphorus provides improved corrosion protection of carbon steel.

Synthesis and characterization of polyaniline in CTAB/hexanol/water reversed micelle

Synthesis and characterization of polyaniline in CTAB/hexanol/water reversed micelle

Self-Assembly and Characterization of Polyaniline and Sulfonated Polystyrene Multilayer-Coated Colloidal Particles and Hollow Shells

Conductive core-shell particles were prepared by the deposition of polyaniline (PANI) and poly(sodium 4-styrenesulfonate) (PSS) multilayers onto polystyrene (PS) colloidal particles via the alternate electrostatic layer-by-layer (LbL) assembly technique. PSS was used as a polymeric counterion for multilayer formation as well as a stabilizer and codopant for PANI. Electrophoresis, FT-IR spectroscopy, and transmission electron microscopy (TEM) confirmed the regular growth of PSS/PANI multilayers on PS colloidal particles. It was found that the PSS/PANI-coated particle is oxidatively more stable due to stabilization of the partially oxidized emeraldine salt by PSS. The conductivity of (PSS/PANI)5-coated PS particles was 0.003 S/cm and increased to 0.1 S/cm after additional dopant exposure with HCl vapor. Furthermore, hollow shells made up of PSS/PANI layers were produced by dissolution of the PS core from PSS/PANI-coated particles. Cyclic voltammetry (CV) showed that PSS/PANI multilayers maintained their oxi...

FABRICATION AND CHARACTERIZATION OF MULTILAYER WAVEGUIDE FOR INTEGRATED OPTICS

We report on our systematic and detailed study of fabrication and characterization of polyaniline (PA) prepared by vacuum deposition and polystyrene (PS) prepared by dip coating method thin film optical waveguides. The four-layer consisting of substrate (glass)/PA/PS/air has been used for demonstrating polarization filter action.

Characterization of Polyaniline and Poly(m-toluidine)-based Nanoparticles of Ultranarrow Particle Size Distribution

The oxidative polymerization of aniline or m-toluidine, carried out in concentrated solutions of poly(vinyl alcohol-co-acetate) (PVA), was used to prepare colloidal composite particles of polyaniline-PVA or poly(m-toluidine)-PVA of ultranarrow particle size distribution and of controlled average particle size. The particle size distributions were measured by quasi-elastic light scattering in diluted polymerization products. Such a measurement can be influenced by undestroyed PVA aggregates formed in the initial solution. The aim of this work was to determine conditions under which the true particle size distribution of the composite particles can be measured or, at least, estimate the degree such a determination is influenced by PVA aggregates not incorporated into the composite particles. Quasi-elastic light scattering measurements of the diluted polymerization products were carried out under various experimental conditions. The composite particles were separated from the PVA solution by centrifugation and redispersed in water. The size of the redispersed composite particles and of the PVA aggregates in the supernatant solution was measured again by quasi-elastic light scattering. Scanning electron microscopy showed the spherical shape of the synthesized composite particles and confirmed their ultranǎrrow size distribution.

Growth and characterization of polyaniline 7,7,8,8-tetracyanoquino-dimethane (TCNQ) complex films grown by vacuum evaporation

High quality polycrystalline polyaniline/7,7,8,8-tetracyanoquino-dimethane (PANI–TCNQ) complex thin films have been grown by vacuum evaporation. A scanning tunneling microscope, transmission electron microscopy and high resolution scanning electron microscopy characterized the films. The films showed totally different optical and electrical properties from both of PANI and TCNQ films. Unusual two-dimensional aggregates were observed in the films. A charge transfer phenomenon, from the PANI chains to the TCNQ molecules, was observed from the Fourier transfer infrared spectrum. Compared with that of PANI and TCNQ thin films, the structural and electrical properties of the PANI–TCNQ thin films are discussed.

Characterization of polyaniline by cyclic voltammetry and UV-Vis absorption spectroscopy

Characterization of polyaniline (PANI) by electrochemical and spectroscopic techniques are presented. The electrochemical investigation reveals the influence of the dopant acid on the kinetic parameters of polyaniline films: exchange current density (I0) and the cathodic transfer coefficient (αc). UV-Vis spectra of thin films of polyaniline in N-metil pyrrolidine solutions indicate the increase of the absorbance with the number of deposition cycles, N. The inhibition of polymer degradation in thick films was confirmed by these spectra.