Polyaniline Matrix Research Articles

Glucose oxidase immobilized PANI cladding modified fiber optic intrinsic biosensor for detection of glucose

In the present study, we report design, development and study of polyaniline (PANI) cladding modified fiber optic intrinsic glucose biosensor (FOIGB) for glucose sensing applications. Chemically and biologically sensitive material PANI has been exploited for the preparation of sensing element by cladding modification technique. Enzyme-glucose oxidase (GOx) was immobilized on porous supportive matrix of PANI using glutaraldehyde as a cross-linking agent. As-synthesized and deposited PANI film on fiber optic core was characterized by ultraviolet–visible and Fourier transform infra-red spectroscopies. X-ray diffraction and field emission scanning electron microscopy were employed to study structure and morphology of modified cladding. Sensing parameters, such as modal power distribution (MPD), sensing response, selectivity and stability were analyzed in order to study the performance of sensor. These parameters were determined by measuring change in optical power and MPD. The sensor, stored at a temperature 4°C, showed lowest detection limit of 10nM and found stable up to 36 days. It also showed good selectivity toward glucose and stability with high result reproducibility.

Fabrication of Electrospun Nanofibers of Titanium Dioxide Intercalated Polyaniline Nanocomposites for CO2 Gas Sensor

In this paper we report the synthesis and characterization of nanofibers of titanium-dioxide (TiO2) intercalated polyaniline (PANI) nanocomposites at room temperature in air at relative humidity of 60% by electrospinning technique. The as-prepared nanofibers were characterized using UV-VIS, FTIR, SEM and XRD. Optical absorbance revealed the shifting of the characteristic peaks for PANI, which may be due to presence of titanium dioxide in PANI matrix. FTIR spectra show the presence of Ti-O-Ti vibrational peak and characteristic vibrational peaks of PANI indicating the interaction of TiO2 particles with PANI. SEM micrographs revealed the formation of fibers with the diameter less than 200nm. XRD patterns showed the characteristic peaks not only for PANI but also for rutile phase of TiO2 particles proving the existence of TiO2 particles within the composites. The as-prepared nanofibers of TiO2 intercalated PANI nanocomposites when exposed to CO2 gas (1000ppm) at room temperature; it was found that the resistance of the nanocomposites was increased from their respective unexposed values. The nanofibers of TiO2 intercalated PANI nanocomposites were found to be good materials for CO2 gas sensor even at room temperature as compared to that of pure TiO2.

Electrical and Dielectric Properties of Polyaniline and Polyaniline/Montmorillonite Nanocomposite Prepared by Solid Reaction Using Spectroscopy Impedance

The combination of two components with uniform distribution in nanoscale is expected to facilitate wider applications of the material. In this study, polyaniline (PAn) and polyaniline/montmorillonite (Mt) nanocomposite were prepared by solid reaction using persulfate of ammonium as oxidant. The phase composition and morphology of the nanocomposite were characterized by FTIR, UV‐visible spectroscopy, X‐ray diffractometer, thermal gravimetric analysis, and scanning electron microscopy. The electrical and dielectric properties were determined using spectroscopy impedance. The analysis of UV‐visible and FTIR spectroscopy demonstrated that aniline chloride has been polymerized into PAn in its conducting emeraldine form. Thermogravimetric analysis suggested that PAn chains intercalated in the clay host are more thermally stable than those of free PAn prepared by solid‐solid reaction. Electrical measurements were carried out using the complex impedance technique in the frequency range of 10−2 to 104 Hz at different temperatures. The ac conductivity data of different nanocomposites were analyzed as a function of frequency and temperature. It has been found that the incorporation of inorganic clay phase into polyaniline matrix has an effect on the electrical and dielectric properties of the nanomaterial.

Dielectric Properties of Polyaniline-Hexaferrite Composites

Polyaniline was synthesized using aniline as monomer, and Y-type hexaferrite with composi-tion Co2Mn2Sr1.6Nd0.4Fe10O22 was prepared by co-precipitation assisted by surfactant. Three composites of Polyaniline with different ferrite ratios were prepared by mechanical blending. The synthesized samples were characterized by X-Ray diffraction and electrical measurements. The XRD analysis reveals single-phase Y-type hexagonal ferrite. In Polyaniline-Ferrite composites the increase in real and imaginary part of complex permittivity was observed with the increase of ferrite filler in the polyaniline matrix. At low frequencies the magnitude of dielectric constant and complex permittivity is high and decrease at high frequencies with few relaxation peaks.

Electrospun Nanofibers of Conducting Polyaniline/Al-SnO2 Composites for Hydrogen Sensing Applications

In this paper, we report the synthesis and characterization of composites of polyaniline and aluminum doped tin oxide (Al-SnO2/PANI) nanofibers for hydrogen gas sensing application. Al-SnO2/PANI composite nanofibers have been fabricated via electrospinning technique and subsequent calcination procedure. The as-prepared Al-SnO2/PANI composite nanofibers were investigated for structural characterizations by means of SEM, FTIR, UV-VIS and XRD. SEM revealed the nanofibers with the diameter around 200-300nm formed a non-woven material with highly porous and agglomerated structure. FTIR and UV-VIS spectra revealed the possible incorporation of Al-SnO2 in PANI and confirmed the uniform attachment of PANI on the surface of Al-SnO2 nanostructures. XRD showed peak broadening and the peak positions shift from standard values, indicating presence of aluminum doped tin oxide in nanoparticles form in the polyaniline (PANI) matrix. On exposure to hydrogen gas (1000ppm), it was found that the nanofibers of Al-SnO2/PANI composite showed high sensitivity at 48 oC with relatively faster response/recovery as compared to pure SnO2 and Al doped SnO2 nanofibers.

Nickel nanocatalysts supported on sulfonated polyaniline: potential toward methanol oxidation and as anode materials for DMFCs

Deposition of nickel nanocatalysts on a sulfonated polyaniline matrix for the fabrication of an efficient catalyst system towards methanol oxidation.

Preparation and enhanced properties of polyaniline/grafted intercalated ZnAl-LDH nanocomposites

The polymeric nanocomposites (PANI/AD-LDH) were prepared by in situ polymerization based on polyaniline (PANI) and decavanadate-intercalated and γ-aminopropyltriethoxysilane (APTS)-grafted ZnAl-layered double hydroxide (AD-LDH). FTIR and XRD studies confirm the grafting of APTS with decavanadate-intercalated LDH (D-LDH). The extent of grafting (wt%) has also been estimated on the basis of the residue left in nitrogen atmosphere at 800°C in TGA. SEM and XPS studies show the partial exfoliation of grafted LDH in the PANI matrix and the interfacial interaction between PANI and grafted LDH, respectively. The grafted intercalated layered double hydroxide in reinforcing the properties of the PANI nanocomposites has also been investigated by open circuit potential (OCP), tafel polarization curves (TAF), electrochemical impendence spectroscopy (EIS), salt spray test and TGA-DTA. The experimental results indicate that the PANI/AD-LDH has a higher thermal stability and anticorrosion properties relative to the PANI.

Ultrasound assisted synthesis of PANI/ZnMoO4 nanocomposite for simultaneous improvement in anticorrosion, physico-chemical properties and its application in gas sensing

Ultrasound assisted in-situ semi-batch emulsion polymerization has been used for the preparation of polyaniline (PANI) and PANI/ZnMoO4 nanocomposite with different loading of ZnMoO4 (ZM) nanoparticles. ZM nanoparticles were functionalized using Myristic acid (MA) for better compatibility with PANI. The cavitational effects induced due to ultrasonic irradiations have been shown significant enhancement in the dispersion of functionalized ZM nanoparticles into the PANI during ultrasound assisted in-situ emulsion polymerization process. TEM images of PANI/ZM nanocomposite particles give the direct evidence of fine dispersion and encapsulation of MA treated ZM nanoparticles in PANI matrix. The presence of ZM nanoparticles in PANI/ZM nanocomposite shows significant improvement in the mechanical (cross-cut adhesion), thermal, anticorrosion and sensing properties of PANI/ZM nanocomposite/alkyd coatings over PANI/alkyd and neat alkyd resin coating. Fine and uniform dispersion of ZM nanoparticles in PANI matrix using this novel synthesis method (PANI (p-type)/ZM (n-type) hetero-junction) improves LPG sensing ability and minimizes response time to sense LPG significantly compared with neat PANI.

Activated carbon nanotubes/polyaniline composites as supercapacitor electrodes

Chemically A-MWCNT (activated multiwalled carbon nanotube)/PANI (polyaniline) composites produced via ultrasonic polymerization of an aniline monomer in the presence of A-MWCNTs were investigated as potential electrode materials for supercapacitors. These composites were compared to pristine MWCNTs and MWCNT/PANI composites. The influence of the pore structure, which developed because of the polymerization process, was investigated by measuring N2 adsorption/desorption isotherms at 77 K. The electrochemical properties of the materials were determined by cyclic voltammetry and galvanostatic charge–discharge cycling measurements in 1 M NaNO3 electrolyte solution, using a three-electrode system at room temperature. The results suggested that the pore structure of the A-MWCNTs could effectively promote the homogenous-dispersion of aniline and consequently result in excellent cycling performance. Furthermore, interaction between the π-conjugated structure of carbon and the quinoid ring of the PANI matrix can lead to enhancement in the charge transfer process.

ChemInform Abstract: Recent Progress in the Preparation of Polyaniline Nanostructures and Their Applications in Anticorrosive Coatings

AbstractReview: 148 refs.

Thermal Stability and Electrical Conductivity of Graphite Nanosheets/Polyaniline Composites

Composites of graphite nanosheets (GNS) fillers in a polyaniline (PANI) matrix doped with dodecylbenzene sulfonic acid were synthesized by polymerization with the aid of sonication. The resulting GNS/PANI composites were characterized by scanning and trans-mission electron microscopy, Fourier transform infrared spectroscopy, X-ray photo-electron spectroscopy, thermogravimetry and electrical conductivity. The results showed that the GNS play an important role in the improvement of thermal stability and electrical conductivity of the composites. Especially, followed the change of GNS contents of the composites, the results of the thermal stability analysis and electrical conductivity analysis got the same variation trend. When the GNS contents for PANI reached 5 wt% in the composites, the best thermal stability and the maximum value of electrical conductivity (6.48 S·cm-1) were obtained.

In situ electrochemical synthesis of polyaniline/f-MWCNT nanocomposite coatings on mild steel for corrosion protection in 3.5% NaCl solution

Abstract Nanostructured composites increase their sensitivity and performance when employed as coating material in corrosive environments. This present study was conducted to elucidate the use of functionalized carbon nanotubes (CNTs) as reinforcement to enhance the corrosion and mechanical behavior of polyaniline (PANI) coatings for the protection of mild steel (MS) structures. Different techniques like Raman spectroscopy, ATR-IR and FESEM analysis were used to evaluate their structure and morphology. FESEM images of the fabricated PANI/f-CNT composites suggest excellent dispersion of CNTs in PANI matrix with one-dimensional core–shell structure. PANI/f-CNT nanocomposite shows an improvement in the mechanical properties with an increase in the hardness value. Hydrophobic nature of nanocomposite coatings was verified by contact angle measurements. The evaluation of electrochemical corrosion behavior of nanocomposite coated MS was achieved by monitoring the anodic current–potential polarization curves and electrochemical impedance response. Finally, it was concluded that PANI/f-CNTs nanocomposite coatings are potentially employed as anticorrosive coatings for mild steel against corrosive environment.

Epoxy Polyaniline–SBA15/Fluconazole Hybrid Nanocomposite Coatings: As a Self-Healing Corrosion Protection of Mild Steel

The objective of this research is the production of an epoxy coating blended with organic–inorganic hybrid nanocomposite applied over mild steel, as a self-healing corrosion protection of defects. A series of conducting polyaniline (PANI)–SBA15/Fluconazole nanocomposites materials are being prepared by an in situ chemical oxidative method of aniline monomers in the presence of SBA15/fluconazole complex nanorods which were synthesized previously with camphor-sulfonic acid (CSA) and ammonium peroxydisulfate (APS) as surfactant and initiator, respectively. A commercial epoxy coating was applied over samples afterwards.The synthesized materials were characterized by X-ray diffraction pattern (XRD), Fourier transform infrared (FTIR), scanning electron microscopy (SEM).To determine the best inhibitor concentration, the anti-corrosion behavior of the Fluconazole was studied in a ammonium sulfide-sodium chloride pH 7 solution, at a temperature of 25 ͦ C using electro-chemical techniques including electrochemical impedance spectroscopy (EIS) and polarization potentiodynamic. The electrochemical results show that this inhibitor has an effect on anodic region forming a passivation layer, and the best result was achieved with 150 ppm of Fluconazole.The next step was to prepare the SBA15/Fluconazole nanorods, and finally the PANI-SBA15/Fluconazole composite, and evaluate the self-healing effect over mild steel.It was found that the presence of SBA15/Fluconazole nanorods dispersed in the PANI matrix can significantly improve the corrosion protection and barrier effect performance of the epoxy coating due to the flaky shaped structure of the PANI–SBA15/Fluconazole nanocomposites, evaluated electrochemically.

Unexpected Redox Enhancement and Electrochemical Pseudo-capacitance Performance of Polyaniline/poly(vinyl alcohol) (PAn/PVA) Composite Films

We report significant improvement, though unexpected contrary to intuition, of the redox behaviour and electrochemical pseudo-capacitance of polyaniline (PAn) conducting polymer composited with non-conducting poly(vinyl alcohol) (PVA). Redox and film composition characterizations were carried out using a combination of in situ electrochemical and nanogravimentric techniques. Film structural changes due to the presence of PVA in the matrix of PAn have been studied with FT-IR and XRD as well as thermal analysis techniques such as TGA and DSC. The increase in PAn/PVA film redox responses compared to pure PAn film was observed to be a factor of ca. 2 while electrochemical capacitance enhancement was obtained to be ca. 40% increase (ca. 130 F g−1 for PAn/PVA composite film compared to ca. 94 F g−1 for PAn). These drastic improvements of composite film's redox behaviour were attributed to the increase in film chain-chain interactions due to the presence of multiple hydrogen bonding created by the introduction of PVA chain segments in the bulk of PAn film and thus enhancing the rate of film redox conversions. Redox enhancement was also associated to the increase in composite film's ion doping capacity.

Chemical Vapour Sensing Properties Of Electrospun Nanofibers Of Polyaniline/ ZnO Nanocomposites

Zinc oxide (ZnO) nanoparticles were synthesized by simple route of sol-gel method and nanofibers of polyaniline (PANI) and PANI/ZnO nanocomposites prepared using the electrospinning technique. Electrospun nanofibers of PANI and PANI/ZnO nanocomposites were collected on aluminum substrate for characterization and on Cu-interdigited electrodes to prepare chemiresistor sensor. Electrospun nanofibers of PANI and PANI/ZnO nanocomposites have been characterized by UV-Visible (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). UV-Visible spectra of nanofibers of PANI/ZnO nanocomposites show hypsochromic shift as that of PANI and some interaction due to ZnO in PANI matrix. The observed changes in the FTIR spectra of the fibers of PANI/ZnO nanocomposites are assosciated with the formation of H-bonding between ZnO and the N-H group present in the PANI chains. X-ray diffraction patterns exhibits hexagonal wurtzite structure of ZnO and broad amorphous peaks of PANI. Heterogeneous structures with fibrous characteristics of diameter less than 300nm of PANI/ZnO nanocomposites are identified in the SEM images. The electrical properties were characterized by I-V characteristic measurements. The changes in resistance of the chemiresistor sensor were utilized for detection of HCl and NH3 chemical vapour at room temperature. The resistance of the sensors was found to be decreased when they were exposed to HCl vapours whereas the resistance of the sensors was found to be increased when they were exposed to NH3 vapours. It was observed that PANI/ZnO nanocomposite sensor shows a high response and sensitivity with good repeatability as compared to that of pure PANI. Sensitivity result shows that PANI/ZnO nanocomposite is highly sensitive to chemical vapours even at room temperature and at very low concentration. Copyright © 2014 VBRI press.

Effect of silver nanoparticle embedment on the frequency dispersive conductivity and electrical relaxation dynamics in dodecylbenzenesulfonic acid-doped polyaniline

The present work aims at studying electrical relaxations in silver–polyaniline nanocomposites using dielectric spectroscopy. The nanocomposites of dodecylbenzenesulfonic acid-doped polyaniline (PANI) with different concentrations of silver nanoparticles (~6–12 nm) are synthesized by simple wet-chemical route. The temperature dependence of dc conductivity in all the samples follows three-dimensional variable range-hopping conduction mechanism. The loss factor, after having subtracted the dc contribution, shows a relaxation peak which simultaneously attributes to the frequency dispersion in conductivity spectra. The observed dielectric relaxation is well fitted by the Havriliak–Negami function, and the fitting parameters are determined. The temperature dependence of characteristic relaxation frequency and dc conductivity is in line with each other and bear a resemblance to the origin of dc transport and dielectric relaxation in these systems. The temperature behavior of the relaxation strength confirms that an exclusive hopping conduction of polarons in the disordered PANI matrix can be considered as the origin of the observed electrical properties of the systems. Further, the self-similar behavior of the real part of normalized ac conductivity, within the measured temperature range, also confirms the above inferences. The variation of frequency exponent with temperature suggests that ac conduction is due to the correlated barrier hopping of polarons which strongly affected by the dispersion of silver nanoparticles within the PANI matrix.

Adsorption studies of a direct dye using polyaniline coated activated carbon prepared from Prosopis juliflora

An attempt was made to prepare an activated carbon from Prosopis juliflora seeds and it was coated in a polyaniline matrix. The prepared adsorbent has a BET surface area of 1028m2/g. The adsorbent was analyzed for its ability to remove Direct Red 23 in its aqueous solution. Effect of pH proves that maximum uptake of DR23 by PPAC was obtained at pH 3.0. The adsorption of DR23 by PPAC follows pseudo second-order kinetics with a very high correlation coefficient of 0.9968<r2<0.9996. The intra particle model proves that pore diffusion plays a major role for the adsorption DR23 on to PPAC. The Langmuir monolayer adsorption capacity (Q0) increases from 90.91 to 109.89mg/g while increasing the temperature from 30 to 45°C. Column model analysis was also carried out to evaluate the adsorbent performance for continuous operation. Thomas, Yoon–Nelson and Bohart–Adams mathematical models were applied to evaluate the column performance. YN model provides excellent fit with very high r2 (0.9844–0.9953) and low Sd (0.09–0.37).

Synthesis and characterization of CoFe2O4/polyaniline nanocomposites for electromagnetic interference applications.

The Cobalt ferrite (CoFe2O4) powders were synthesized by Co-precipitation method. The as prepared ferrite powders were incorporated into a polyaniline matrix at various volumetric ratios. The as prepared composites of ferrite and polyaniline powders were characterized using X-ray diffraction (XRD), transmission electron microscope (TEM). The particle size of CoFe2O4 is found to be 20 nm. The saturation magnetization (M(s)) of all the composites was found to be decreasing with decrease of ferrite content, while coercivity (H(c)) remained at the value corresponding to pure cobalt ferrite nanopowders. The complex permittivity (epsilon' and epsilon") and permeability (mu' and mu") of composite samples were measured in the range of 1 MHz to 1.1 GHz. The value of epsilon' and mu' found to be increased with ferrite volume concentration.

Synthesis and Characterization of Polyaniline–Mn3O4 Nanocomposite: Electrical Conductivity and Magnetic Studies

Polyaniline (PANI)–Mn3O4 nanocomposites (NCs) have been synthesized by in situ chemical oxidative polymerization of aniline with different molar ratios of aniline:Mn3O4 (3.3:1 and 2.5:1) using ammonium per sulfate as an oxidant in an aqueous solution of sodium dodecyl benzene sulfonic acid, as surfactant and dopant at 5 °C under N2 atmosphere. The structural components and the crystalline phase of the Mn3O4 nanoparticles (NPs) and PANI–Mn3O4 NCs were identified from Fourier transform infrared spectroscopy and X-ray diffraction. The result of FTIR and TGA shows that the interaction between Mn3O4 particles and PANI matrix could improve the thermal stability of NCs. The room temperature electrical conductivity of the synthesized PANI, PANI-Mn3O4 NCs (3.3:1) and (2.5:1) was found to be 3.26 × 10−4, 8.11 × 10−7 and 3.93 × 10−7 S/cm respectively, indicating the decrease of conductivity with an increase of Mn3O4 content in PANI. The magnetic behavior of composite was studied at 5 K. The coercive force (Hc) and remnant magnetization (Mr) increases with increase in addition of Mn3O4 NPs in PANI matrix.

Highly selective electrochemical sensor for ascorbic acid based on a novel hybrid graphene-copper phthalocyanine-polyaniline nanocomposites

In this work, we designed a novel electrochemical sensing platform based on graphene (Gr)/copper(II) phthalocyanine-tetrasulfonic acid tetrasodium salt (CuPc)/polyaniline(PANI) nanocomposites. The prepared composites were used to modify screen printed electrodes (SPE) for selective determination of ascorbic acid (AA) in presence of dopamine (DA) and uric acid (UA). Copper phthalocyanine was immobilized on graphene sheets by π-π interaction by electrolytical exfoliation and resulting CuPc/graphene was embedded in a PANI matrix to prevent leakage of Gr/CuPc from electrodes. The Gr/CuPc/PANI nanocomposites were characterized by scanning electron microscopy (SEM), UV-vis spectroscopy, cyclic voltammetry (CV) and amperometry. The prepared modified electrode presents good electrocatalytic properties, fast response time, high stability and reproducibility. The performance of the sensor exhibited a linear range from 5×10−7 to 1.2×10−5M with low a limit of detection of 6.3×10−8M (S/N=3) and the sensitivity of the sensor was found to be 24.46μAmM−1. Moreover, the nanocomposites show excellent selectivity and lower potential for the oxidation of ascorbic acid. The novel sensor successfully applied to determination of AA in real samples with satisfactory results. This can open up new opportunities for fast, simple and selective detection of AA and provide a promising platform for sensor or biosensor designs for AA detection.