Amount Of Polyaniline Research Articles

Nitrogen-Doped Graphene Nanoribbons as Efficient Metal-Free Electrocatalysts for Oxygen Reduction

Nitrogen-doped graphene nanoribbon (N-GNR) nanomaterials with different nitrogen contents have been facilely prepared via high temperature pyrolysis of graphene nanoribbons (GNR)/polyaniline (PANI) composites. Here, the GNRs with excellent surface integration were prepared by longitudinally unzipping the multiwalled carbon nanotubes. With a high length-to-width ratio, the GNR sheets are prone to form a conductive network by connecting end-to-end to facilitate the transfer of electrons. Different amounts of PANI acting as a N source were deposited on the surface of GNRs via a layer-by-layer approach, resulting in the formation of N-GNR nanomaterials with different N contents after being pyrolyzed. Electrochemical characterizations reveal that the obtained N8.3-GNR nanomaterial has excellent catalytic activity toward an oxygen reduction reaction (ORR) in an alkaline electrolyte, including large kinetic-limiting current density and long-term stability as well as a desirable four-electron pathway for the formation of water. These superior properties make the N-GNR nanomaterials a promising kind of cathode catalyst for alkaline fuel cell applications.

A comparative study of Fe3O4/polyaniline composites with octahedral and microspherical inorganic kernels

Studies have been carried out on the microwave absorption properties of the title composites. The dielectric loss of each material correlated well with its microwave absorption properties. However, these properties are not affected significantly by whether the kernel is octahedral or hollow spherical. Samples with variable amounts of polyaniline were synthesized and it was found that the maximum reflection loss occurs at around 50 % of polyaniline for both octahedral and micro-spherical Fe3O4/polyaniline composites showing that the amount of interface between Fe3O4 and polyaniline plays a key part in enhancing the absorbance although other effects are also important. Hollow spherical Fe3O4 was synthesized using ammonium acetate. However, it was noted that when sodium acetate was used, fewer cracks appeared in the material. The presence of cracks is evidence for the hollow nature of spherical Fe3O4. A clad growth mechanism is proposed for the formation of the composite material.

Manufacturing Technique and Property Evaluations of Conductive Nonwoven Fabrics

Conductive textiles can be used in diverse fields, such as antistatic materials, sensors, materials for electromagnetic shielding and biomedical. This study produces nonwoven fabrics with polylactic acid (PLA) and polyaniline (PAN) and the resulting PLA/PAN nonwoven fabrics are evaluated with electromagnetic shielding effectiveness (EMSE) and air permeability. Polylactic acid (PLA) and low melting point polylactic acid (LPLA) are made into nonwoven fabrics, which are then spray-coated with different amount of PAN solution to form PLA/PAN nonwoven fabrics. The fabrics are laminated with various numbers of layers, and then thermally pressed. The experiment results show that the PAN amount and lamination number are proportional to the EMSE of the PLA/PAN nonwoven fabrics.

Low-voltage blue-phase liquid crystals with polyaniline-functionalized graphene nanosheets

A small amount of polyaniline functionalized graphene (G–PANI, 0.03–2.00%) nanosheets was doped into conventional polymer-stabilized blue phase liquid crystals (PS-BPLCs), and the electro-optical property effects were studied. The driving capability of BPLCs can be much improved in that the Kerr constant of BPLCs doped with 0.05 wt% G–PANI is increased by ∼55% compared with that of BPLCs without G–PANI. Meanwhile, this composite exhibits no degradation of electro-optical properties, such as response time, hysteresis and residual birefringence.

Parallel spinnerets electrospinning construct and properties of electrical-luminescent bifunctional bistrand-aligned nanobundles

A structure of electrical-luminescent bifunctional bistrand-aligned nanobundles has been successfully fabricated by specially designed parallel spinnerets electrospinning technology. Eu(BA)3phen (BA = benzoic acid, phen = 1,10-phenanthroline) and polyaniline (PANI) were respectively incorporated into polyvinyl pyrrolidone (PVP) and electrospun into bistrand-aligned nanobundles with PANI/PVP as one strand nanofiber and Eu(BA)3phen/PVP as another strand nanofiber. The morphologies and properties of the final products were investigated in detail by scanning electron microscopy, transmission electron microscopy, fluorescence spectroscopy, Hall effect measurement system, and UV–Vis-NIR spectrophotometer. It is found that the as-prepared samples exhibit the nanostructures of bistrand-aligned nanobundles. The mean diameter for individual nanofiber of the bistrand-aligned nanobundles is 180 nm. The [PANI/PVP]//[Eu(BA)3phen/PVP] bistrand-aligned nanobundles possess excellent electrical conduction and luminescent properties. Fluorescence emission peaks of Eu3+ are observed in the [PANI/PVP]//[Eu(BA)3phen/PVP] electrical-luminescent bifunctional bistrand-aligned nanobundles and assigned to 5D0 → 7F0 (581 nm), 5D0 → 7F1 (592 nm), 5D0 → 7F2 (615 nm) energy levels transitions of Eu3+ ions, and the 5D0 → 7F2 hypersensitive transition at 615 nm is the predominant emission peak. The electrical conductivity reaches up to the order of 10−3 S/cm. The electrical conductivity and luminescent intensity of the bistrand-aligned nanobundles can be tunable by adding various amounts of PANI and rare earth complex. The novel [PANI/PVP]//[Eu(BA)3phen/PVP] electrical-luminescent bifunctional bistrand-aligned nanobundles have potential applications in display devices and nanomechanics, etc. owing to their excellent electrical conduction and fluorescence.

Dielectric study of polyaniline/poly (methylmethacrylate) composite films below the percolation threshold

Abstract We report results of dielectric relaxation studies of polyaniline/poly(methylmethacrylate) composites with polyaniline amount less than the percolation threshold in the frequency range of 0.1 Hz to 1 MHz and temperature range of 10 °C–170 °C. We find a significant dependence of the glass transition temperature Tg on the polyaniline amount in the composite. α and β relaxation processes relative to the PMMA matrix are also affected by the presence of polyaniline inclusion. We identify a relaxation process due to ionic conductivity and another process attributed to residual solvent. The characteristic relaxation frequency of each process and the activation energy depend on the polyaniline amount in the composite. The ac conductivity in the high frequency range is fitted to the universal power law of Jonscher characteristic of disordered materials.

Polyaniline‐tailored electromechanical responses of the silver/epoxy conductive adhesive composites

ABSTRACTIn this article, the electromechanical properties of silver‐in‐epoxy conductive adhesives with the polyaniline (PANI) micron particles as cofillers have been investigated. PANI is a conductive polymer and has a moderate conductivity in between those of silver and epoxy. It was found that PANI can be used to tailor both the adhesive's electrical contact resistance and its relaxation behavior; however, the effects of adding PANI were complex. The addition of small amount of PANI (2 wt %) dramatically increased the contact resistance; it might block the electrical contacts among silver flakes and was not able to form a continuous path among themselves. The addition of more PANI showed a moderate increase in contact resistance, which increased with the weight fraction of PANI from 6 to 15 wt %. Interdependent behavior of compressive strain and relaxation in electrical contact resistance is characterized to evaluate the origin of this relaxation. The addition of PANI made the relaxation in electrical contact resistance more sensitive to the compressive strain and the electromechanical coupling to deviate from the linear relationship. These research findings provide insights into the way to use PANI to tailor the electromechanical properties of the adhesive bonds or joints in the development of advanced functional devices. © 2013 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys, 2013, 51, 1448–1455

Improvement of Microbial Fuel Cell Performance by Using Nafion Polyaniline Composite Membranes as a Separator

The characteristics of four new proton-conducting membranes, Nafion112/polyaniline composite membranes of various compositions, are studied for application as membrane separators in microbial fuel cells. The composite membranes are made by immersing Nafion-112 membranes in a solution containing aniline for different immersion times. The presence of polyaniline and sulfonic functional groups in the composite membranes is confirmed by means of Fourier transform infrared analysis while their surface roughness is determined by using atomic force microscopy prior to microbial fuel cell operation. Biofouling on the membranes' surface is also examined by using a scanning electron microscope after microbial fuel cell operation. The polarization curves and, hence, the power density curves are measured by varying the load's resistance. The power density of the microbial fuel cell with the Nafion/polyaniline composite membranes improves significantly as the amount of polyaniline increases because the interaction between sulfonic groups in the Nafion matrix and polyaniline in the polyaniline domains increases proton conductivity. However, it declines after more polyaniline is added because of less conjugated bonding of polyaniline and sulfonic acid groups for larger polyaniline domains in the Nafion matrix. The voltage overpotential is also smaller as the amount of polyaniline increases. Biofouling also decreases with increasing polyaniline in the Nafion/polyaniline composite membranes because they have smoother surfaces than Nafion membranes. The results show that the maximum power generated by the microbial fuel cells with Nafion112-polyaniline composite membrane is 124.03 mV m−2 with a current density of 454.66 mA m−2, which is approximately more than ninefold higher than that of microbial fuel cells with neat Nafion-112. It can be concluded that the power density of the microbial fuel cell can be increased by modifying the Nafion membrane separators with more conductive polymers that are less susceptible to biofouling to improve its proton conductivity.

Preparation and characterization of Pt nanoparticles supported on modified graphite nanoplatelet using solution blending method

Platinum nanoparticles have been successfully assembled on polyaniline functionalized graphite nanoplatelet (GNP) via a noncovalent functionalization strategy. The characterization of obtained nanocomposite was investigated by XRD, TEM, XPS and electrochemical technology. When the moderate amount of polyaniline as a stabilizer, Pt nanoparticles with sizes of approximate 4–5 nm uniformly disperse on GNP surface. In methanol oxidation reaction, the electrocatalytic activity of Pt/PANI-GNP is nearly 2 times higher than that of Pt/GNP catalyst. Through analysis, it is suggested that the electrocatalysis performance of Pt/PANI-GNP may be improved by the following four factors: (1) uniformly distributed nanoparticle; (2) increased of amount of Pt0 and oxygen-containing groups; (3) the existence of N atoms; (4) difference reaction mechanism.

UV‐curable acrylate‐based nanocomposites: effect of polyaniline additives on the curing performance

Composites of nanostructured polyaniline (PANI) conducting polymer in a polyester acrylate (PEA) formulation were made to provide conductive organic coatings. The effect of the presence and amount of PANI on the photocuring performance of the ultraviolet (UV)‐curable acrylate system has been investigated employing real‐time Fourier transform infrared spectroscopy as the main technique. Longer initial retardation of the radical polymerization and lower rates of cross‐linking reactions were observed for dispersions containing PANI of higher than 3wt.%. The PEA/PANI samples were more affected than the neat PEA resin by the changes in UV light intensity and oxygen accessibility during UV curing. Samples with higher PANI content, of up to 10wt.%, were tested and could be partially cured even at UV light intensities as low as 2 mW cm−2 when the oxygen replenishment into the system was inhibited. Thermal analysis revealed that the presence of PANI did not induce any significant change in Tg of the cured system, meaning that early decrease in mobility and vitrification is not the reason for lower ultimate conversion of the dispersions with higher PANI content compared with the neat PEA resin. Curing under strong UV lamps, of 1.5 W cm−2 intensity, made it possible to reach high degrees of conversion on films with similar mechanical properties independent of the PANI content. Copyright © 2013 John Wiley & Sons, Ltd.

Preparation, characterization and electrical conduction mechanism of polyaniline/ordered mesoporous silica composites

In this work, we have shown the preparation of polyaniline (PANI) and mesoporous ordered silica (SBA-15) composites. PANI/SBA-15 composites with different weight ratios were prepared in order to evaluate the electrical conduction mechanism. The analysis of the differential activation energy was carried out for composites, allowing the classification of the variable range hopping as one dimensional for the composites. The hopping parameter as a function of the sample mass ratio indicates that the insertion of aniline into the mesopores improves its intrinsic conductivity. A fibrilar morphology of the conducting PANI is formed by a controlled amount of the added polymer into SBA-15. It was confirmed by SEM and TEM analysis that the composites prepared with different PANI contents have different morphologies, indicating that the amount of polyaniline is crucial to obtain distinct morphologies. SAXS, NAI, TEM and SEM show that SBA-15 maintains its structure even after the polymerization process and the polymer is dispersed on the inorganic matrix. The parameters determined by the investigation of variable range hopping conduction by the differential activation energy method show that the PANI produced in these composites have higher electrical conductivity than pure PANI, possibly due to the improvement of the interparticle, interchain and intrachain processes for the charge transport, which are intimately related to the polymer morphology, fact coherent with SEM and TEM data.

Enhancement of microwave absorption of polyaniline–PbTiO3 composites prepared by using sodium dodecyl benzene sulfonoic acid

Abstract

Structural and electrochemical characterization of polyaniline/LiCoO2 nanocomposites prepared via a Pickering emulsion

Polyaniline (PANI)/LiCoO2 nanocomposite materials are successfully ready through a solid-stabilized emulsion (Pickering emulsion) route. The properties of nanocomposite materials have been put to the test because of their possible relevance to electrodes of lithium batteries. Such nanocomposite materials appear thanks to the polymerization of aniline in Pickering emulsion stabilized with LiCoO2 particles. PANI has been produced through oxidative polymerization of aniline and ammonium persulfate in HCl solution. The nanocomposite materials of PANI/LiCoO2 could be formed with low amounts of PANI. The morphology of PANI/LiCoO2 nanocomposite materials shows nanofibers and round-shape-like morphology. It was found that the morphology of the resulting nanocomposites depended on the amount of LiCoO2 used in the reaction system. Ammonium persulfate caused the loss of lithium from LiCoO2 when it was used at high concentration in the polymerization recipe. Highly resolved splitting of 006/102 and 108/110 peaks in the XRD pattern provide evidence to well-ordered layered structure of the PANI/LiCoO2 nanocomposite materials with high LiCoO2 content. The ratios of the intensities of 003 and 104 peaks were found to be higher than 1.2 indicating no pronounced mixing of the lithium and cobalt cations. The electrochemical reactivity of PANI/LiCoO2 nanocomposites as positive electrode in a lithium battery was examined during lithium ion deinsertion and insertion by galvanostatic charge–discharge testing; PANI/LiCoO2 nanocomposite materials exhibited better electrochemical performance by increasing the reaction reversibility and capacity compared to that of the pristine LiCoO2 cathode. The best advancement has been observed for the PANI/LiCoO2 nanocomposite 5 wt.% of aniline.

Diffusion characteristics of surface-modified ion-exchange membranes based on MK-40, MF-4SK, and polyaniline

Asymmetric membrane materials based on MK-40 membranes modified with a thin layer of MF-4SK perfluorinated ion-exchange resins with incorporated polyaniline have been studied. The diffusion characteristics of the resulting composites have been analyzed. It has been proved that the membranes with polyaniline undergo a decrease in diffusion permeability, which indicates an increase in selectivity. The modified membranes exhibit a higher cation transport rate. The diffusion coefficients of individual cations in mixed cationic membranes have been estimated. It has been shown that the introduction of small amounts of polyaniline leads to an increase in the proton transport rate.

Electrical and thermal properties of graphite/polyaniline composites

A composite of a carbon allotrope (graphite) and an inherently conducting polymer, polyaniline (PANI), has been prepared that exhibits an electrical conductivity greater than either of the two components. An almost 2-fold increase in the bulk conductivity occurs when only a small mass fraction of polyaniline exists in the composite (91% graphite/ 9% polyaniline, by mass). This increase in dc electrical conductivity is curious since in most cases a composite material will exhibit a conductivity somewhere between the two individual components, unless a modification to the electronic nature of the material occurs. In order to elucidate the fundamental electrical properties of the composite we have performed variable temperature conductivity measurements to better understand the nature of conduction in these materials. The results from these studies suggest a change in the mechanism of conduction as the amount of polyaniline is increased in the composite. Along with superior electrical properties, the composites exhibit an increase in thermal stability as compared to the graphite.

Electrorheological properties of polyaniline/K-feldspar conducting composite

In this study, synthesis of conducting polyaniline (PAn)/potassium-feldspar (K-feldspar) composites, having various amounts of PAn, was carried out using (NH4)2S2O8 as oxidizing agent. The conducting composites were characterized by a series of techniques namely: Fourier transform–infrared, X-ray diffraction, scanning electron microscopy, thermogravimetry analysis, two-probe conductivity, magnetic susceptibility, and particle size measurements. For electrorheological (ER) measurements, the conductivities of the composites were reduced by a dedoping process. A series of suspensions were prepared in silicone oil, having various volume fractions, and then subjected to colloidal stability, flow rate, ER and creep-recovery tests. Enhancement in the electric field-induced viscosities and shear thinning non-Newtonian viscoelastic behavior was observed for all the composite materials studied. Recoverable viscoelastic deformations were detected from the creep and creep-recovery tests under externally applied electric field thus; they were classified as smart materials.

Synthesis of conductive adhesives based on epoxy resin/nanopolyaniline and chloroprene rubber/nanopolyaniline: Characterization of thermal, mechanical and electrical properties

Dodecylbenzenesulfonic acid-doped polyaniline was prepared by sonication method. Electrically conductive blends were prepared by mixing a polyaniline–dodecylbenzenesulfonic acid salt with epoxy resin and chloroprene rubber. The nanostructure of the conductive blends was studied by scanning electron microscopy. The polyaniline/epoxy resin and polyaniline/chloroprene rubber showed threshold concentrations of polyaniline (5 and 10 wt%, respectively) for electrical conduction. The electrical conductivity of both polyaniline/epoxy resin and polyaniline/chloroprene rubber increased with the addition of polyaniline–dodecylbenzenesulfonic acid, reaching values higher than 1.89 × 10−2 and 7.50 × 10−4 S/cm with 50 wt% of polyaniline–dodecylbenzenesulfonic acid. The structures of conductive adhesives were investigated by Fourier transform infrared spectroscopy. Also the thermal, mechanical, and adhesion strength properties of blends containing different amounts of polyaniline–dodecylbenzenesulfonic acid were determined.

Dc and Ac conductivity of polyaniline/poly (methyl methacrylathe) blends below the percolation threshold

In this work we present results of thermal spectral and conductivity studies on polyaniline/poly (methylmethacrylate) composite films with polyaniline Wt% situated under the percolation threshold. The glass transition temperature Tg is significantly modified by the presence of polyaniline. For polyaniline Wt% not exceeding 0.3%, the Tg decreases, but for specimens having highest amounts it increases. The Uv–Visible absorption spectroscopy indicates the presence of characteristic absorption bands of polyaniline. When the amount of polyaniline is increased from 0% to 0.5%, the dc conductivity shows an increase with a maximum attained at about 0.1% followed by a decrease. A correlation with the variation of Tg in this domain of polyaniline concentration is proposed.

Preparation, characterization and enhanced visible light photocatalytic activities of polyaniline/Bi3NbO7 nanocomposites

Polyaniline/Bi3NbO7 nanocomposites were successfully prepared by a simple chemisorption approach. Their particle sizes ranged from 25 to 50nm. The photocatalytic activities of the as-prepared samples for the rhodamine B degradation were evaluated under visible light (420nm≤λ≤760nm). The results indicated that the samples exhibited excellent photocatalytic activities and high activity stabilities for the degradation of rhodamine B. When the loading amount of polyaniline was 4wt%, the obtained sample showed the highest photocatalytic activity. Its photocatalytic activity was also much higher than that of the reference sample (TiO2−xNx powders). On the basis of the experimental results, photo-generated holes were detected as the main oxidation species responsible for the decomposition of rhodamine B over polyaniline/Bi3NbO7. Furthermore, the enhanced photocatalytic activity was mainly ascribed to the synergetic effect between polyaniline and Bi3NbO7.

Study on mechanical and thermal properties of composites of cis‐ and trans‐polyisoprene blends filled with polyaniline

AbstractIn this study, the effect of polyaniline (PANI) as filler has been investigated on the mechanical and thermal properties of blends of cis‐polyisoprene (CPI) and trans‐polyisoprene (TPI) by dynamic mechanical analyzer and transient plane source technique, respectively. The samples blend composites with different concentration of PANI have been prepared by solution casting method and characterized through X‐ray diffraction. Experimental results from mechanical and thermal measurements show that incorporation of PANI in CPI/TPI blends increases glass transition temperature, mechanical properties and thermal properties whereas decreases damping property. This increase in different properties is only upto a certain amount of PANI and over this amount an entirely apposite behavior is observed. This observed behavior of mechanical and thermal properties is explained on the basis of crystallinity and crosslink density. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers