Electrical Properties Of Polyaniline Research Articles

Facile in-situ preparation of polyaniline/graphene nanocomposites using methanesulfonic acid

Polyaniline (PANI)/graphene composites were prepared by the in-situ polymerization of aniline in a 1 M aqueous solution of methanesulfonic acid (MSA) containing graphene, which was prepared separately from graphite powders by simple sonication in MSA. Graphite powders spontaneously exfoliated to form graphene (GPM), which was then quenched with excess water, filtered, and dried to produce powders. The dried graphene powders produced were re-dispersed well in a 1 M MSA aqueous solution, in which the in-situ polymerization of aniline was performed. The resulting PANI/GPM composite had a conducting emeraldine salt (ES) form, and showed good electrical and thermal properties, compared to pure PANI prepared using a 1 M HCl solution. The PANI/GPM composite could be dissolved in a MSA solution and spin-coated in a conducting ES form of PANI. In contrast, the ES form produced from a HCl solution was insoluble in organic solvents and needed to be reduced to convert it to the emeraldine base form to produce a PANI solution. Therefore, the in-situ preparation of PANI/graphene composites using MSA provides a facile means of improving the thermal and electrical properties of PANI and its processability.

Swift heavy ion irradiation-induced enhancement in structural, conformational and electrical properties of polyaniline nanofibers

We report here the irradiation effects of 160 MeV Ni12+ ion beam on the structural and electrical properties of polyaniline (PAni) nanofibers synthesized by the interfacial polymerization method. The morphological studies show an increase in average diameter of PAni nanofibers upon swift heavy ion (SHI) irradiation. X-ray diffraction results show the amorphous nature of PAni nanofibers and upon SHI irradiation its crystallinity (K) and average crystallite size or extent of order (L) increase with increasing ion fluence. Fourier transform infrared spectroscopy results confirm the formation of PAni and suggest better conjugation length of PAni chains with increasing ion fluence. The ac conductivity follows the universal power law, σac=A ωs with (0<s<1) and upon irradiation conductivity increases appreciably with fluence. The decreasing behavior of frequency exponent s with temperature suggests correlated barrier hopping transport of charge carriers. Current–voltage characteristics of PAni nanofibers show the non-ohmic behavior and the current increases with increasing ion fluence. Thermogravimetric analysis exhibits enhanced thermal stability of PAni nanofibers upon SHI irradiation.

Simultaneous numerical optimization of the mechanical and electrical properties of polyaniline coated kenaf fiber using response surface methodology: nanostructured polyaniline on natural fiber

Response surface methodology was used to simultaneously optimize the electrical and mechanical properties of newly developed conducting biofibers made up of kenaf fiber/polyaniline (KF/PANI). The effect of process parameters such as PANI amount (1–10 wt.%), dopant concentration (5–25 N), and molar ratio of aniline/oxidant solutions (0.5–1.5) were studied using Design of Experiment. Both of the responses (electrical conductivity and unit break) obtained a quadratic model. The experimental values were in good agreement compared to the optimized process. The scanning electron microscope images of the optimized sample revealed uniform PANI component on the KF with nanofibrillar features.

Curing kinetics, thermomechanical and microwave behaviors of PANI-doped BSA/epoxy resin composites

This work focuses on the elaboration and characterization of conducting polymer composites based on polyaniline (PANI) dispersed in an epoxy resin (ER) matrix and cured using an anhydride without a catalyst. PANI-doped benzene sulfonic acid was successfully synthesized in this manner and used as conducting filler. The effect of heating rate and PANI loading level on the curing process was investigated by differential scanning calorimetry in the dynamic mode. Furthermore, the phase structure, viscoelastic behavior and hardness of the composites were explored by dynamic mechanical thermal analysis and Vickers tests. The structure and morphology of the samples were investigated by scanning electron microscopy, which revealed behavior that varied as a function of the concentration of PANI in the composites. Dielectric properties were investigated up to 1 MHz. The electromagnetic shielding effectiveness of the composites was measured in the microwave band from 8 to 18 GHz. It was found that the electrical properties of PANI were influenced by elevated curing temperature of the ER, a variable that significantly affected the composite characteristics. In addition, the dielectric properties, curing parameters, viscoelasticites and electromagnetic behaviors of the composites were affecting by increasing the concentration of PANI filler in the matrix.

Flexible, all-organic ammonia sensor based on dodecylbenzene sulfonic acid-doped polyaniline films

A stable chlorobenzene dispersion of conducting polyaniline (PANI) has been obtained by doping emeraldine base with dodecylbenzene sulfonic acid (DBSA) and studied by spectrophotometric measurements in the UV–vis–IR range. The electrical properties of PANI: DBSA films obtained from the above dispersion have been investigated under different temperature and relative humidity conditions. All-organic chemoresistive devices have been developed by spin-coating the PANI: DBSA dispersion on flexible substrates, and then by depositing electrodes on the top, from a carbon nanotube conducting ink. Sensing tests performed under exposition to calibrated amounts of ammonia reveal that these simple and inexpensive sensors are able to detect ammonia at room temperature in a reliable way, with a sensitivity linearly related to concentration in the range between 5 ppm and 70 ppm.

Optical and electrical transport properties of polyaniline–silver nanocomposite

Polyaniline–silver nanocomposite has been synthesized successfully by the chemical oxidative polymerization of aniline with ammonium peroxydisulphate as an initiator in presence of negatively charged silver nanoparticles. Silver nanoparticles are prepared by standard citrate reduction method. TEM, SEM, XRD, FTIR, TGA, DSC, optical absorption and photoluminescence studies are done for the morphological, structural, thermal and optical characterization of the polyaniline nanocomposite. From the TEM and SEM image, it is observed that nanoparticles are well dispersed in the polyaniline matrix. XRD pattern shows that polyaniline is amorphous, but peaks present in XRD pattern in polymer nanocomposites are for silver nanoparticles. TGA and DSC results show that polyaniline silver nanocomposite is more crystalline and more thermally stable. A surface plasmon absorption band is obtained from the optical absorption at 380 nm, which indicates that silver nanoparticles are present in the polyaniline matrix. The optical band gap of nanocomposite decreases with increasing content of silver nanoparticles. An enhancement in photoluminescence has been observed in polyaniline–silver nanocomposite than that in pure polyaniline. The electrical conductivity of polyaniline–silver nanocomposite increases with increase in silver nanoparticle content than that of pure polyaniline. This is a simple way by which optical and electrical properties of polyaniline may be enhanced by doping with suitable nanoparticles.

Structure and electrical properties of polyaniline synthesized in presence of low magnetic field

Abstract Chemical polymerization of aniline is carried out in the presence of low magnetic field (1 kG and 2 kG). The impact of application of magnetic field externally during polymerization increases the electrical conductivity by two orders of magnitude. This enhanced electrical conductivity depends on ordering of polymer chain, structure, molecular weight, magnetic susceptibility, and thermal characteristics of polyaniline which has been studied and reported.

Electrical Properties of Polyaniline and Multi-Walled Carbon Nanotube Hybrid Fibers

We have fabricated for the first time one-dimensional multiwalled carbon nanotube (MWNT) nanocomposite fibers with improved electrical properties using electrospinning. Polyaniline (PANi) and poly(ethylene oxide) (PEO) were used as a conducting and a nonconducting matrix, respectively, for hybrid nanofibers including MWNTs. The hybrid nanofibers fabricated by electrospinning had a length of several centimeters and a diameter ranging from approximately 100 nm to approximately 1 microm. Transmission electron microscopic analysis confirmed that the MWNTs were successfully oriented along the fiber axis without any severe aggregation during electrospinning. The hybrid nanofibers showed an enhanced electrical conductance with increasing MWNT content up to 0.5 wt%, and compared to PANi/PEO fibers, they also showed a stable linear ohmic behavior. These hybrid conducting nanofibers can be applied to chemical and biosensors that require a high sensitivity.

Electrochemistry of conductive polymers: 41. Effects of self-assembled monolayers of aminothiophenols on polyaniline films

Effects of self-assembled monolayers (SAMs) of a few different aminothiophenols (ATPs) on growth, morphology, and electrical properties of polyaniline have been studied at gold electrodes employing current sensing atomic force microscopy. The 4-aminothiophenol (4-ATP) SAM showed the best capability of shuttling electrons from the gold electrode to the solution species, and the 4-ATP SAM covered electrode not only showed the best kinetics for the film growth but also produced the film of the highest electrical conductivity. The vertical conductivity of the film ranged from 58 S cm −1 for a film prepared at a bare gold electrode to as high as 148 S cm −1 for a film obtained at the 4-ATP SAM covered electrode. The conductivity was shown to depend on the thickness of the films as well as how they were prepared.

Effects of surface and volume modification of poly(vinylidene fluoride) by polyaniline on the structure and electrical properties of their composites

The structure and electrical properties of polyaniline (PANI) modified poly(vinylidene fluoride) (PVDF) films have been studied depending on the type of modification (surface or volume) and the type of dopant (HCl or dodecylbenzenesulfonic acid). The structure was studied with differential scanning calorimetry, atomic force microscopy and Raman spectroscopy (including the surface enhanced mode—SERS) techniques. Surface modification of PVDF with PANI creates a two-dimensional (2D) conductive network on the surface of PVDF films with the thickness of approximately 8 μm. The network is characterized with non-linear current voltage ( I– V) characteristics and enhanced conductivity at elevated temperatures (up to 160 °C), which is opposite to volume modified samples behaviour. Conductivity of the composite films varies in the range of 10 −8 to 10 −3 S/cm depending on the preparation conditions. The observed non-linear conductivity is explained by formation of the surface conductive network of PANI alternated with β-crystalline PVDF microdomains.

Electrical properties of polyaniline and polypyrrole bilayer structures

We have studied the electrical properties for conductive polyaniline (PANI) and polypyrrole (PPy). Also, bilayer structures consisted of electrochemically deposited PPy and PANI films onto PPy and PANI substrates prepared by chemical oxidative polymerization were investigated. In order to obtain structures with a high stability of electrical properties, the dopants compatibility with the polymers was studied. Special attention is given to I-V characteristics of the structures. On the basis of the experimental results, the electrical properties of bilayer structures based on PPy and PANI combined by different ways are described. In addition, the adhesive properties of different adherent layers, one to another, are discussed.

The Structure and Electrical Properties of Polyaniline

AbstractThe anisotropic structure of EB polyaniline films cast from N, N'-Dimethylpropylene urea (DMPU) solution and stretched to different draw ratios was studied by infrared dichroism. The drawn films were doped with 1.0 M HCl and the electrical properties were studied by impedance spectroscopy. A new test fixture has been developed to measure the in-plane impedance of polymeric films. A Debye-like conductivity relaxation was observed for all the HCl-doped PANI samples. The conductivity along the stretch direction increases with molecular orientation. The in-plane conductivity is significantly higher than the through-plane conductivity.

Radiation Induced Effects on Electrical Properties of Polyaniline

The effect of radiation on the electrical conductivity of polyaniline in the reduced, undoped and doped states has been studied. A model based on the oxidation of the polymeric chain combined with radiolysis of the adsorbed water molecule has been proposed to explain the radiation-induced effects in this polymer. The experimental results show that the film resistance of emeraldine base, and leucoemeraldine salts decrease drastically with exponential decay for the range from 0 to 250 Gy, when exposed to γ radiation, while for emeraldine salt the resistance slightly decreases with exponential decay for low doses of radiation and increases linearly for high doses. Infrared analysis performed in irradiated emeraldine base strongly support a proton doping effect of the polymeric material induced by radiation.

Improved conductivity and electrical properties of polyaniline in the presence of rare-earth cations and magnetic field

The influence of rare-earth cations on the preparation and properties of polyaniline (PANI) was investigated in the presence of a magnetic field. It was found that the addition of rare-earth cations can greatly increase the polymerization rate of PANI in the following order: Tb 3+>Nd 3+>Ce 3+. When a parallel magnetic field ( B p) was imposed with respect to the electrode surface, the maximum polymerization rate was obtained at B p=0.5 T. Whereas, in a perpendicular magnetic field ( B s), the rate was accelerated as the magnetic flux density rose. The conductivity of PANI/Tb 3+/ B p=0.7 T film was 115.4 S cm −1 which, as expected, is higher by about an order of magnitude as compared to the parent PANI film without the effects of rare-earth cations and magnetic field. Meanwhile, the X-ray diffraction patterns and electrochemical impedance spectroscopy indicated an increase of crystallinity and a more-ordered arrangement of the polymer chains with a concurrent increase in the capacitance, and a decrease in the charge transfer resistance and the ohmic resistance in the presence of rare-earth cations and magnetic field.

Doped polyaniline with C 60

The electronic structure and the electrical properties of polyaniline (PANI) doped with C 60 were measured as a function of the concentration of C 60 molecules and preparation conditions. For lower C 60 concentration (less than 1.0 mol. %), a series of experimental results suggests that the enhanced conductivity of PANI-C 60 composites may be due to acid doping PANI in air. For higher C 60 concentrations (10–20 mol. %), however, the charge transfer between PANI and C 60 molecules in PANI-C 60 composites was observed from UV-Visible absorption and the FTIR spectrum. Poor conductivity of PANI-C 60 composites at room temperature may be attributed to a low degree of doping and the large size of C 60 molecules as dopants, which results in a decrease in the conductivity along and between the PANI polymer chains.

Electrical properties of polyaniline and substituted polyaniline derivatives

Polyaniline and substituted polyaniline derivatives which the ortho position hydrogen is substituted with CH 3, OCH 3 and Cl are studied. Both protonic acid doping (i.e. the addition of protons to the polymer chain without changing the number of electrons in the chain) and the acceptor doping (i.e., the number of electrons in the polymer chain is decreased by the acceptor which is iodine in this case) results on these samples show metallic conductivity. On the other hand, the signs of thermoelectric power are different. The sign of protonic acid doped polyaniline becomes negative upon doping, but the sign of the acceptor doped sample remains positive. The effect of the substitution of ortho hydrogen is more significant in the protonic acid doping than in the iodine doping. Electron affinity of the substituted molecules could affect the electronic structure of the polyaniline. The electrical conductivity and thermoelectric power measurement data as functions of doping concentration and temperature for these samples are presented.