Synthesis Of PANI Research Articles

Green and low-cost synthesis of PANI–TiO2 nanocomposite mesoporous films for photoelectrochemical water splitting

Green and low-cost synthesis procedure for preparation of PANI/TiO2 mesoporous nanocomposite films with enhanced photocatalytic performance, thanks to a synergic reaction mechanism between PANI and TiO2 under UV light irradiation.

Biotemplate synthesis of polyaniline@cellulose nanowhiskers/natural rubber nanocomposites with 3D hierarchical multiscale structure and improved electrical conductivity.

Development of novel and versatile strategies to construct conductive polymer composites with low percolation thresholds and high mechanical properties is of great importance. In this work, we report a facile and effective strategy to prepare polyaniline@cellulose nanowhiskers (PANI@CNs)/natural rubber (NR) nanocomposites with 3D hierarchical multiscale structure. Specifically, PANI was synthesized in situ on the surface of CNs biotemplate to form PANI@CNs nanohybrids with high aspect ratio and good dispersity. Then NR latex was introduced into PANI@CNs nanohybrids suspension to enable the self-assembly of PANI@CNs nanohybrids onto NR latex microspheres. During cocoagulation process, PANI@CNs nanohybrids selectively located in the interstitial space between NR microspheres and organized into a 3D hierarchical multiscale conductive network structure in NR matrix. The combination of the biotemplate synthesis of PANI and latex cocoagulation method significantly enhanced the electrical conductivity and mechanical properties of the NR-based nanocomposites simultaneously. The electrical conductivity of PANI@CNs/NR nanocomposites containing 5 phr PANI showed 11 orders of magnitude higher than that of the PANI/NR composites at the same loading fraction,; meanwhile, the percolation threshold was drastically decreased from 8.0 to 3.6 vol %.

Effect of Zn source concentration on structural, optical and electrical properties of zinc sulphide–polyaniline (ZnS–PANI) nanocomposite thin films

Zinc sulphide–polyaniline (ZnS–PANI) nanocomposites are prepared by preparing ZnS nanoparticles in the same reaction bath for synthesis of PANI. Three different composites have been prepared by varying the concentration of zinc source. The films obtained from the colloidal dispersion are characterized by Scanning electron microscopy, energy dispersive analysis of X-rays, transmission electron microscopy, X-ray diffraction studies, Fourier transform infrared spectroscopy, UV–visible optical absorption, photoluminescence and current–voltage studies. Broadening of X-ray diffraction peaks suggest change in crystallite size and this is in agreement with the results from transmission electron microscopy. Fourier transform infrared spectra indicate crosslinking in the composite film. UV–visible absorption spectra of the film exhibit enhancement of doping level which is assigned to the existence of greater number of charges on the polymer backbone. Optical properties of the films are studied by measuring photoluminescence spectra. This shows decrease in intensity and blue shift with the increase in zinc source concentration. The blue shift indicates strong quantum confinement. Current–voltage characteristics exhibit excellent light response indicating tunneling type of conduction.

Electrochemical Synthesis of PANI on 316L Stainless Steel Bipolar Plates of PEMFC and its Corrosion Performance

PANI conducting polymer coating was electrochemically deposited on 316L stainless steel bipolar plates of PEMFC in the bath of 0.5M H2SO4 and 0.5M aniline. PANI coating could be synthesized with optimal conditions presenting in smooth and dense feature when the voltage was from 0.75V to 0.85V(Vs.SCE). The anti-corrosion performance of the coating was evaluated by electrochemical technique in the medium of 1M H2SO4 and 2ppM NaF at 70°C to simulate the working environment of PEMFC. It was found that the anodic branch of polarization curves presented in passivation character. EIS results indicated that the radius of the capacity impedance for PANI coating increased distinctly, which validated the excellent corrosion resistance of the coating. The surface morphology of the coating was observed by SEM, and the results showed that the surface of 316L stainless steel bipolar plates was covered by claviform shape coating. The chemical composition of the coating was investigated by FTIR and the results illustrated that the coating were composed of PANI.

One-Step Synthesis, Characterization, and Properties of Emeraldine Salt Nanofibers Containing Gold Nanoparticles

This paper reports a simple one-step synthesis of gold nanospheres/polyaniline (PANI) nanofiber composites via the modification of the interfacial synthesis of PANI, leading to hybrid materials with emeraldine salt fibers as one of the components. Their morphological and structural characterizations are presented, as well as their electrochemical behaviors. The composites were submitted to heating treatment and UV–visible light radiation, and the products were characterized. Our results showed that the presence of the gold nanoparticles improved the thermal behavior of the composites, increasing the onset temperature. The electroactivity and capacity of the composites were enhanced when compared to PANI–ES, and their behaviors are dependent on the amount of gold nanoparticles in the composites. Submitting to heating treatment and UV–visible light irradiation, the PANI–ES nanofibers presented low dedoping and an extensive formation of cross-linking segments for both treatments, whereas the composites showe...

Interfacial polymerization of polyaniline and its layer‐by‐layer assembly into polyelectrolytes multilayer thin‐films

AbstractThe layer‐by‐layer (LbL) self assembly deposition technique was used to prepare multilayer thin films of anionic polyaniline‐blend‐poly(sodium 4‐styrenesulfonate) (PANI‐PSS) and cationic poly(diallydimethylammonium chloride) (PDADMAC). Anionic polyaniline was prepared by the interfacial polymerization of aniline monomer in the presence of PSS which acted as template to provide water solubility. The PSS to PANI concentration ratios used in the synthesis step was found to have a major effect on the final PANI‐PSS synthesis, its self assembly and the electrical properties of the prepared films. The optical and electrical properties of the films were measured by ultraviolet‐visible spectroscopy (UV‐Vis) and a 4‐point probe setup, respectively while the thickness of the films was measured by atomic force microscopy (AFM). Results showed that the optimum condition for the film growth and optimal conductivity were obtained with different synthesis conditions. These results suggest that the PSS concentration used for interfacial synthesis of PANI must be finely tuned depending on the type of application aimed by the user. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis of PANI and Study of Morphology in the Process of Polymerization

AbstractThe polyaniline micro/nanostructure was prepared by a self‐assembly process with molybdic acid as dopants in the presence of ammonium persulfate as the oxidant. It was found that the morphology of PANI micro/nanostructure was affected by the concentration of the dopant, that is, the morphology of PANI changed from nanofibers to co‐existence of nanofibers and microspheres as the molar ratio of molybdic acid to aniline varied from 0.01 to 1.5. Under the same condition it was also found that the conductivity value of PANI enhanced from 4.58×10−3 S·cm−1 to 3.8×10−1 S·cm−1. The structure of PANI was characterized by FTIR and XRD which confirmed the presence of the molybdic acid in the PANI. The electrochemical characteristics of the PANI nanofibers were investigated by means of cyclic voltammetry. The morphology of PANI in the process of polymerization was characterized by SEM. It was found that when the molar ratio of molybdic acid to aniline was 0.3, the morphology of PANI was co‐existence of nanofibers and microspheres and the formation of microspheres was ahead of the nanofibers.

Electrochemical impedance spectroscopy investigation of chlorinated rubber‐based coatings containing polyaniline as anticorrosion agent

AbstractCorrosion protection of mild steel by a newly developed chlorinated rubber (CR)‐based coating system containing the inherently conductive polymer polyaniline (PAni) as an anticorrosion agent was studied. The synthesis of PAni and preparation of CR‐based paint containing this polymer are described herein. The corrosion behavior of mild steel samples coated with a CR resin, CR/PAni‐EB (emeraldine base), CR/PAni‐ES (emeraldine salt), and CR/DBSA‐doped PAni were investigated in 3.5% NaCl solution. For this purpose, electrochemical impedance spectroscopy and corrosion potential versus time measurements were utilized. It was found that the addition of the two forms of PAni, doped and undoped, to the CR resin increased its corrosion protection efficiency.

Polyaniline Morphology and Detectable Intermediate Aggregates

AbstractFormation of detectable intermediate aggregates is found to affect the morphologies of PANI nanomaterials, leading to either tubular or rod structures with striated growth and rough surfaces. By simply varying the ratio of initial proton and aniline concentration, a wide range of product morphologies can be synthesized. The intermediates form visible aggregates that can be separated by centrifugation or filtration. In addition to UV‐Vis monitoring of the intermediate aggregates, OCP and pH measurements are used to monitor the reaction process. GPC measurements show that the corresponding final products formed typically are not homogeneous. The correlation of intermediates formation and aggregation with product morphology suggests a route to controlled synthesis of PANI nanomaterials.magnified image

Synthesis of polyaniline using horseradish peroxidase immobilized on plasma‐functionalized polyethylene surfaces as initiator

AbstractThe doping of semiconducting conjugated polymers (e.g., polyaniline, PANI) can result in the elimination of the bandgap, leading to high electrical conductivities (comparable to metals). Doped PANI is totally insoluble and thus nonprocessable, which considerably limits its practical applications. Synthesis of PANI using immobilized horseradish peroxidase (HRP) as a catalyst in aqueous solutions can open up additional possibilities for applications through the direct synthesis of controlled‐thickness PANI layers on various substrate surfaces. The RF plasma‐enhanced surface functionalization of polyethylene and the covalent immobilization of HRP are discussed, and the polymerization of aniline initiated by immobilized HRP is presented. The nature of plasma‐grafted surface functionalities on the substrate surfaces and the formation of PANI are demonstrated using X‐ray photoelectron spectroscopy and attenuated total reflectance Fourier transform IR spectroscopy. The molecular weight distribution of PANI is evaluated with gel permeation chromatography, and the activity of the immobilized enzyme is monitored using UV spectroscopy. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 369–379, 2003

ENZYMATIC SYNTHESIS OF MOLECULAR COMPLEXES OF POLYANILINE WITH DNA AND SYNTHETIC OLIGONUCLEOTIDES: THERMAL AND MORPHOLOGICAL CHARACTERIZATION

The assembly of electronic and photonic materials on biomacromolecules is of tremendous interest for the development of biofunctional nanocomplexes as well as highly selective biosensors. In the context of the use of electrically conducting polymers for sensing, polyaniline (Pani) and polypyrrole have received considerable interest because of their well-known electrical properties. Recently, we have reported an enzyme catalyzed synthetic procedure involving horseradish peroxidase (HRP) for the polymerization of aniline on a calf thymus DNA matrix. The mild reaction conditions involved in the synthesis have provided opportunities for the use of more delicate biomacromolecules as templates. The complexation of Pani with DNA has been found to induce reversible changes in the secondary structure of DNA leading to the formation of an over-wound polymorph. The thermal characterization (melting behavior) of the DNA in the complex and the morphological properties of the complex have provided corroborative evidence for the wrapping of Pani around the DNA matrix. Scanning probe and electron microscopy studies have indicated that the formation of Pani causes the DNA-Pani strands to agglomerate, presumably due to the neutralization of charge on the phosphate groups by the partially charged Pani. We also report the synthesis of Pani on a synthetic oligonucleotide (Poly[dA-dC].poly[dG-dT]). Demonstration of the use of a new biomimetic catalyst, polyethylene glycol modified hematin (PEG-hematin), in these reactions will also be presented. These results indicate that this biocatalytic synthetic approach is generic, versatile and can be adopted for both genomic and synthetic nucleic acids. †Deceased.

Biochemical Synthesis and Unusual Conformational Switching of a Molecular Complex of Polyaniline and DNA

AbstractPolyaniline (Pani) is one of the most interesting conducting polymers because of its promising electrical properties and unique redox tunability. Recently a new template assisted, enzymatic synthetic approach has been developed which yields a water-soluble and conducting complex of polyaniline and the template used. The mild reaction conditions in this approach allow for the utilization of delicate biological systems as template materials, such as DNA. Here we report the extension of this enzymatic approach to the synthesis of Pani on a DNA matrix. DNA serves as a suitable template for complexation and formation of conducting polyaniline. The redox behavior of Pani induces reversible conformational change in the secondary structure of DNA. Circular dichroism results suggest that the secondary structure of the DNA may be reversibly switched through manipulation of the redox state of the polyaniline.