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Enzyme immobilization on Ag nanoparticles/polyaniline nanocomposites

CRESPILHO, Frank N.; IOST, Rodrigo M.; TRAVAIN, Silmar A.; OLIVEIRA JUNIOR, Osvaldo Novais de; ZUCOLOTTO, Valtencir
Fonte: ELSEVIER ADVANCED TECHNOLOGY Publicador: ELSEVIER ADVANCED TECHNOLOGY
Tipo: Artigo de Revista Científica
ENG
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We show a simple strategy to obtain all efficient enzymatic broelectrochemical device, in which urease was immobilized oil electroactive nanostructured membranes (ENMs) made with polyaniline and silver nanoparticles (AgNP) stabilized in polyvinyl alcohol (PAni/PVA-AgNP). Fabrication of the modified electrodes comprised the chemical deposition of polyaniline followed by drop-coating of PVA-AgNP and urease, resulting in a final ITO/PAni/PVA-AgNP/urease electrode Configuration. For comparison. the electrochemical performance of ITO/PAni/urease electrodes (without Ag nanoparticles) was also studied. The performance of the modified electrodes toward Urea hydrolysis was investigated via amperometric measurements, revealing a fast increase in cathodic current with a well-defined peak upon addition of urea to the electrolytic solution. The cathodic currents for the ITO/PAni/PVA-AgNP urease electrodes were significantly higher than for the ITO/PAni/urease electrodes. The friendly environment provided by the ITO/PAni/PVA-AgNP electrode to the immobilized enzyme promoted efficient catalytic conversion of urea into ammonium and bicarbonate tons. Using the Michaelis-Menten kinetics equation, a K(M)(aPP) of 2.7 mmol L(-1) was obtained. indicating that the electrode architecture employed may be advantageous for fabrication of enzymatic devices with improved biocatalytic properties. Crown Copyright (C) 2009 Published by Elsevier B.V. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP; CAPES; Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq); CNPq; Ministério da Ciência...

Electrospinning of Hyperbranched Poly-L-Lysine/Polyaniline Nanofibers for Application in Cardiac Tissue Engineering

FERNANDES, Edson G. R.; ZUCOLOTTO, Valtencir; QUEIROZ, Alvaro A. A. De
Fonte: TAYLOR & FRANCIS INC Publicador: TAYLOR & FRANCIS INC
Tipo: Artigo de Revista Científica
ENG
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Electrospun polyaniline nanofibers are one of the most promising materials for cardiac tissue engineering due to their tunable electroactive properties. Moreover, the biocompatibility of polyaniline nanofibes can be improved by grafting of adhesive peptides during the synthesis. In this paper, we describe the biocompatible properties and cardiomyocytes proliferation on polyaniline electrospun nanofibers modified by hyperbranched poly-L-lysine dendrimers (HPLys). The microstructure characterization of the HPLys/polyaniline nanofibers was carried out by scanning electron microscopy (SEM). It was observed that the application of electrical current stimulates the differentiation of cardiac cells cultured on the nanofiber scaffolds. Both electroactivity and biocompatibility of the HPLys based nanofibers suggest the use this material for culture of cardiac cells and opens the possibility of using this material as a biocompatible electroactive 3-D matrix in cardiac tissue engineering.

Spectroscopic investigation of the interactions between emeraldine base polyaniline and Eu(III) ions

IZUMI, Celly M. S.; BRITO, Hermi F.; FERREIRA, Ana Maria D. C.; CONSTANTINO, Vera R. L.; TEMPERINI, Marcia L. A.
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
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The interactions of emeraldine base form of polyaniline (EB-PANI) and Eu(III) ions in 1-methyl-2-pyrrolidinone (NMP) solution and in films have been investigated by UV-vis-NIR, resonance Raman. luminescence and electron paramagnetic resonance (EPR) spectroscopies. These spectroscopic techniques allowed to characterize quinone and semiquinone segments in the polymeric chains. and the oxidation state of europium ions in Eu-PANI samples. For high values of Eu(III)/N molar ratio (24/1) the presence of a weak polaronic absorption band at 980 nm in UV-vis-NIR spectrum and the observation of bands at 1330 and 1378 (nu(center dot)(C-N+)) cm(-1) due to emeraldine salt in the Raman spectrum at 1064 nm indicate a low doping degree. Oxidation of EB-PANI to pernigraniline base (PB-PANI) occurs in diluted solutions. The experimental data showed that the solvent plays an important role on the nature of formed species. The narrow EPR signal at g = 2.006 (line width 8G) confirms the presence of PANI radical cations in Eu-PANI film. The absence of broad signal characteristic of Eu(II) in EPR spectrum suggested that europium ions are primarily at Eu(III) oxidation state. The luminescence spectra of Eu-PANI film presented emission bands at 405 and 418 nm assigned to PANI moieties and bands at 594...

Structure of polyaniline formed in different inorganic porous materials: A spectroscopic study

NASCIMENTO, Gustavo M. do; TEMPERINI, Marcia L. A.
Fonte: PERGAMON-ELSEVIER SCIENCE LTD Publicador: PERGAMON-ELSEVIER SCIENCE LTD
Tipo: Artigo de Revista Científica
ENG
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In this work, the electronic and structural characterization of polyaniline (PANI) formed in cavities of zeolites Y (ZY) and Mordenite (MOR) and montmorillonite (MMT) clay having Cu(II) as oxidant agent are presented. The formation of PANI and its structure is analyzed by Resonance Raman, UV-Vis-NIR, FT-IR and N K XANES techniques. In all cases the structure of PANT formed is different from the ""free"" polymer. The presence of azo bonds linked to phenazine-like rings are observed only for PANI-MMT composites, independent of the kind of oxidant agent employed in the synthesis. The presence of Cu(II) ions leads to the formation of Phenosafranine-like rings. The presence of these phenazine-like rings in the structure of confined PANT chains can also contribute to the enhancement of the thermal stability observed for all composites. (C) 2008 Elsevier Ltd. All rights reserved.; FAPESP; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Polyaniline/layered zirconium phosphate nanocomposites: Secondary-like doped polyaniline obtained by the layer-by-layer technique

IZUMI, Celly M. S.; CONSTANTINO, Vera R. L.; TEMPERINI, Marcia L. A.
Fonte: AMER SCIENTIFIC PUBLISHERS Publicador: AMER SCIENTIFIC PUBLISHERS
Tipo: Artigo de Revista Científica
ENG
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In the present work, nanocomposites of polyaniline (PANI) and layered alpha-Zr(HPO4)(2).H2O (alpha-ZrP) were prepared using two different approaches: (i) the in situ aniline polymerization in the presence of the layered inorganic material and (ii) the layer-by-layer (LBL) assembly using an aqueous solution of the polycation emeraldine salt (ES-PANI) and a dispersion of exfoliated negative slabs of alpha-ZrP. These materials were characterized spectroscopically using mainly resonance Raman scattering at four exciting radiations and electronic absorption in the UV-VIS-NIR region. Structural and textural characterizations were carried out using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The polymer obtained by the in situ aniline polymerization is located primarily in the external surface of the inorganic material although aniline monomers were intercalated between alpha-ZrP interlayer regions before oxidative polymerization. Through resonance Raman spectroscopy, it was observed that the formed polymer has semiquinone units (ES-PANI) and also azo bonds (-N = N-), showing that this method results in a polymer with a different structure from the usual ""head-to-tail"" ES-PANI. The LBL assembly of pre-formed ES-PANI and exfoliated alpha-ZrP particles produces homogeneous films with reproducible deposition from layer to layer...

The role of solvent on the doping of polyaniline with Fe(III) ions

IZUMI, Celly M. S.; RODRIGUES, Daniel C.; TEMPERINI, Marcia L. A.
Fonte: ELSEVIER SCIENCE SA Publicador: ELSEVIER SCIENCE SA
Tipo: Artigo de Revista Científica
ENG
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The products formed from the reaction of emeraldine base polyaniline (EB-PANI) with Fe(III) ions in N-methyl-pyrrolidone (NMP), dimethylacetamide (DMA), dimethylformamide (DMF) and m-cresol media have been investigated using UV-VIS-NIR and resonance Raman (lambda(0) = 632.8 and 1064 nm) spectroscopies. Through these results it was verified that the different PANI forms in solution can be formed by the suitable choice of the solvent. The behavior of Fe(III)/EB-PANI in different solvents was rationalized in terms of the interactions among Fe(III) ions, EB-PANI and solvent. In basic NMP, DMA and DMF media, the reaction of Fe(III) with EB-PANI yields EB-PANI doping giving ES-PANI and/or the EB-PANI oxidation to PB-PANI. The formation of ES-PANI is favored in DMF while PB-PANI is formed in a greater extension in NMP and DMA. In acidic m-cresol, only ES-PANI is produced in Fe(III)/EB-PANI solutions indicating the important role played by the solvent in the nature of the product. (C) 2010 Elsevier B.V. All rights reserved.; Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP); FAPESP; CNPq; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Electrochemical Behaviour of the AA2024 Aluminium Alloy Modified with Self-Assembled Monolayers/Polyaniline Double Films

SILVA, Daiane Piva B.; NEVES, Rodrigo S.; MOTHEO, Artur J.
Fonte: TAYLOR & FRANCIS LTD Publicador: TAYLOR & FRANCIS LTD
Tipo: Artigo de Revista Científica
ENG
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The electrochemical characteristics of the AA2024 aluminium alloy modified with octadecyltrimethoxysilane (ODTMS) + polyaniline (PANi) and propiltrimethoxysilane (PTMS) + (PANi) were studied in the present work. The results show that the different protective coatings shift the values of corrosion and pit potentials to more positive values making the system nobler and indicate that the double film ODTMS + PANi present the best protection against corrosion characteristics, that is probably due to the two contributions: anodic protection associated with the barrier effect.

Preparation and characterization of poly(vinyl butyral)-polyaniline-montmorillonite nanocomposites

Anadao, Priscila; Diaz, Francisco Rolando Valenzuela; Wiebeck, Helio
Fonte: TRANS TECH PUBLICATIONS LTD; STAFA-ZUERICH Publicador: TRANS TECH PUBLICATIONS LTD; STAFA-ZUERICH
Tipo: Artigo de Revista Científica
ENG
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Poly(vinyl butyral)-polyaniline-sodium montmorillonite nanocomposites were prepared via polymerization of aniline between clay mineral platelets at two different pH levels (2.0 and 5.0), followed by dispersion of the polyaniline-sodium montmorillonite nanocomposite in a poly(vinyl butyral) solution. A comparison was made of the effect of the pH levels and the polyaniline-sodium montmorillonite nanocomposite precursor on the final structures of the poly(vinyl butyral) nanocomposites and their electrical conductivities. X-ray diffraction patterns revealed the formation of nanocomposites at both pH levels. UV-Vis spectra indicated that the polyaniline formed at both pH levels was conductive, with the UV-Vis spectra presenting a band at 420 nm corresponding to the polaronic form and the beginning of a new band at 600 nm indicating the presence of polaronic segments. FTIR spectra revealed the peaks of the groups present in polyaniline and poly(vinyl butyral) nanocomposites. The electrical conductivities of the polyaniline and poly(vinyl butyral) nanocomposites prepared at pH 2.0 were lower than those of the same nanocomposites prepared at pH 5.0, probably due to the lower formation of polyaniline chains in a more acidic dispersion and to the final configuration of polyaniline in the nanocomposites.; FAPESP; FAPESP

Filmes de Langmuir e Langmuir-Blodgett de Polianilinas; Langmuir and Langmuir-Blodgett films of polyaniline.

Riul Júnior, Antonio
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/05/1998 PT
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Explorou-se a caracterização de monocamadas e filmes LB de polianilina (PANi), e um oligômero de polianilina, chamado aqui de 16-mero, com estearato de cádmio (CdSt). A análise dos filmes de Langmuir indicou que possivelmente não há mistura em nível molecular da PANi e do 16-mero com CdSt, ainda que a quantidade adicionada em solução de polímero ou oligômero influencie a estabilidade das monocamadas. Utilizou-se UV-vis, FTIR, difração de raios-X, condutividade elétrica, elipsometria, microscopia óptica e potencial de superficie para caracterização dos filmes LB. Os resultados de UV-vis indicaram uma transferência uniforme e ainda que os filmes recém depositados encontram-se desdopados. A análise de FTIR confirma a presença de CdSt nos filmes LB, e o efeito de desdopagem em subfases neutras, corroborando os resultados de UV-vis. A difração de raios-X indica a presença de domínios separados de PANi (e 16-mero) com CdSt nos filmes LB. Resultados elipsométricos indicaram uma espessura por camada em tomo de 25 Å. A excelente uniformidade obtida nos filmes LB mistos foi comprovada pelos resultados de microscopia óptica e potencial de superficie. Esses filmes mistos apresentaram valores de condutividade elétrica em tomo de 10-4 a 10-5 S.cm-1 (van der Pauw)...

Desenvolvimento de membranas e filmes auto-suportados a partir da polianilina : síntense, caracterização e aplicação; Development of membrane and freestanding film as of polyaniline : synthesis, characterization and application

Müller, Franciélli; Ferreira, Carlos Arthur; Amado, Franco Dani Rico; Rodrigues, Marco Antonio Siqueira
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Artigo de Revista Científica Formato: application/pdf
POR
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Polímeros condutores são uma nova classe de polímeros que tem recebido especial interesse para a produção de membranas e filmes. A polianilina (PANI) destaca-se entre eles por sua elevada estabilidade química, fácil polimerização e baixo custo. O objetivo deste trabalho foi desenvolver uma blenda de polímero convencional (HIPS) com polímero condutor (PANI-CSA) e um filme de polianilina auto-suportado, usando ácido canforsulfônico (CSA) como dopante primário e 4-cloro-3-metil fenol (CMC) como dopante secundário. Estes dois materiais foram empregados como membranas íon-seletivas em um sistema de eletrodiálise para remoção de níquel de soluções. A membrana e o filme foram caracterizados por condutividade elétrica, MEV, espectroscopia FTIR, Raman e TGA. Os resultados obtidos apontam para a possibilidade de aplicação da membrana seletiva para eletrodiálise. A extração de níquel para a membrana sintetizada se mostrou semelhante à extração para a membrana comercial. O filme auto-suportado apesar de exibir boa resistência mecânica no estado sólido apresentou comportamento pouco satisfatório quando colocado em imersão com a solução de trabalho para eletrodiálise, devido ao seu estado quebradiço.; Conducting polymers are a new class of polymers that has received particular interest for the production of membranes and films. The polyaniline (PANI) is distinguished among conducting polymers for its high chemical stability...

Effect of the doping medium on blends of polyurethane and polyaniline

Malmonge, J. A.; Campoli, C. S.; Malmonge, L. F.; Kanda, DHF; Mattoso, LHC; Chierice, G. O.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 87-88
ENG
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Flexible and free-standing films from blends of polyurethane, based on castor oil, and polyaniline were obtained with various compositions by casting. Significant increase on conductivity followed by a considerable decrease on doping time was obtained by doping the films in N,N-dimethylformamide (DMF) solution with p-toluene sulphonic acid (TSA) or HCl instead of the conventional doping in aqueous solution. This doping efficiency is proposed to be due to an improved swelling of the blend structure caused by the solvent. The electrical conductivity increases significantly upon polyaniline content increase reaching 10(-2) S/cm for a polyaniline content of about 10% (w/w).

A study on X-ray irradiation of composite polyaniline LB films

Dhanabalan, A.; Malmonge, J. A.; Riul, A.; Faria, R. M.; Oliveira, O. N.
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 808-812
ENG
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Composite Langmuir-Blodgett (LB) films from polyaniline and cadmium stearate have been irradiated with ionizing X-rays for various exposure times. In the initial stages of X-ray irradiation the absorption peak at 580 nm of an as-deposited film was seen to decrease with a concomitant increase in the absorption in the long wavelength region (700-1100 nm). Upon prolonging the irradiation, the absorption maximum shifted to 800 nm with the LB film color changing to green, characteristic of acid doped polyaniline. The changes in the Fourier transform infrared (FTIR) spectra upon irradiation are also similar to those observed upon acid doping of polyaniline. When compared with acid doping, two major differences were observed for the LB films exposed to X-rays. First, the packing order of the cadmium stearate domains in the composite LB films - as observed by X-ray diffraction - is not affected by the X-ray irradiation. In addition, no significant increase in the DC conductivity was noted after the X-ray exposure whereas similar LB films have their conductivity increased by an order of magnitude upon acid doping. These differences may be explained by considering that the inter-domain contribution to the conductivity is increased by the acid doping because the insulating cadmium stearate domains are destroyed...

Zeta potential and doping in polyaniline dispersions

de Medeiros, DWO; dos Santos, D. S.; Dantas, TNC; Pereira, M. R.; Giacometti, A.; Fonseca, JLC
Fonte: Oficyna Wydawnicza Politechniki Wroclawskiej Publicador: Oficyna Wydawnicza Politechniki Wroclawskiej
Tipo: Artigo de Revista Científica Formato: 251-257
ENG
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Polyaniline (PAni) has been classified as an intractable polymer, particularly in its conducting form, the emeraldine salt (ES). Therefore one can consider the mixture of water and PAni as a suspension. The conducting form of PAni can be obtained by a doping process known as acid doping, in which a strong acid turns PAni from its insulating form, the emeraldine base (EB), into the conducting form, the emeraldine salt. With the objective of establishing a correlation between the doping level and the zeta potential of polyaniline dispersions, polyaniline + HCl aqueous suspensions were prepared. Positive zeta potential values for the various suspensions of PAni showed that it acquired positive charges after the doping process. It was also observed an increase in zeta potential values as HCl concentration increased, which could be correlated to UV-visible spectra of PAni suspensions.

Effect of structural anisotropy on electrical and magnetic properties of polyaniline conducting films

Fedorko, P.; Faure-Vincent, J.; Fier, I.; Walmsley, L.; Sniechowski, M.; Jacquot, J. F.; Pron, A.; Travers, J. P.; Djurado, D.
Fonte: Universidade Estadual Paulista Publicador: Universidade Estadual Paulista
Tipo: Artigo de Revista Científica Formato: 63-69
ENG
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It is shown that highly conducting films of polyaniline protonated with di-esters of sulfosuccinic and sulfophthalic acids which contain alkyl- or alkoxy-type substituents exhibit highly anisotropic structural, electrical and magnetic properties. The layered-like structure of these films can be described as consisting of polyaniline chains which are mainly oriented parallel to the plane of the film and form regular out-of-plane stacks. These stacks are separated by bilayers of the dopant anions. Accordingly, the main anisotropy observed for solution cast films implies in-plane and out-of-plane measurements. An electrical anisotropy of about 80 is found for the in-plane and out-of-plane electronic conductivities at 5 K. The temperature dependences of the in-plane and out-of-plane conductivities are qualitatively similar and have been fitted as a series combination of variable-range-hopping-type and power law contributions. A maximum is observed in the temperature dependence of the electrical anisotropy at low temperature. The films also show a clear anisotropy of magnetization whose temperature and field characteristics depend on the chemical structure of the dopant anion. © 2013 Elsevier B.V.

Study of charge compensation during the redox process of self-doped polyaniline in aqueous media

Varela,Hamilton; Torresi,Roberto M.; Buttry,Daniel A.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/02/2000 EN
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One of the most important problems associated with use of polyaniline as a cathode material in rechargeable lithium batteries is related to energy density degradation due to the predomination of anion participation in the charge compensation process. This work describes the synthesis of a self-doped polyaniline, poly-(aniline-co-N-propanesulfonic acid-aniline), and evaluates its properties in aqueous acid solutions, with special attention to the increase of proton participation in the electroneutralization mechanism. The characterization was carried out using elemental analysis, FTIR and UV-vis spectroscopies. Electrochemical properties were investigated with the electrochemical quartz crystal microbalance and cyclic voltammetry. The results obtained show that proton participation was increased for the redox process of poly-(aniline-co- N-propanesulfonic-acid-aniline) in relation to polyaniline.

Electrosynthesized polyaniline for the corrosion protection of aluminum alloy 2024-T3

Huerta-Vilca,Domingo; Moraes,Sandra R.; Motheo,Artur J.
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/01/2003 EN
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Adherent polyaniline films on aluminum alloy 2024-T3 have been prepared by electrodeposition from aniline containing oxalic acid solution. The most appropriate method to prepare protective films was a successive galvanostatic deposition of 500 seconds. With this type of film, the open circuit potential of the coating shifted around 0.065V vs. SCE compared to the uncoated alloy. The polyaniline coatings can be considered as candidates to protect copper-rich (3 - 5%) aluminum alloys by avoiding the galvanic couple between re-deposited copper on the surface and the bulk alloy. The performance of the polyaniline films was verified by immersion tests up to 2.5 months. It was good with formation of some aluminum oxides due to electrolyte permeation so, in order to optimize the performance a coating formulation would content an isolation topcoat.

Chemical modification of polyaniline by N-grafting of polystyrenic chains synthesized via nitroxide-mediated polymerization

Hatamzadeh,Maryam; Mahyar,Ali; Jaymand,Mehdi
Fonte: Sociedade Brasileira de Química Publicador: Sociedade Brasileira de Química
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2012 EN
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This study aims to explore an effective route for the preparation of conductive N-substituted polyaniline (PANI) by the incorporation of brominated poly(styrene-co-p-methylstyrene) onto the emeraldine form of polyaniline. For this purpose, at first, poly(styrene-co-p-methylstyrene) was synthesized via nitroxide-mediated polymerization (NMP), and then, N-bromosuccinimide was used as brominating agent to obtain a copolymer with bromine. Thereafter, deprotonated polyaniline was reacted with brominated poly(styrene-co-p-methylstyrene) to prepare the poly(styrene-co-p-methylstyrene)-graft- polyaniline [(PSt-co-PMSt)-g-PANI] terpolymer through N-grafting reaction. The terpolymer was characterized by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Optical properties of (PSt-co-PMSt)-g-PANI in the undoped and doped states were obtained by ultraviolet-visible spectroscopy (UV-Vis), and electrical conductivity at room temperature was measured using samples in which the conductive materials was sandwiched between two Ni electrodes. Moreover, electroactivity of the synthesized terpolymer was verified under cyclic voltammetric conditions on the surface of the working glassy carbon electrode (GCE). The solubility of (PSt-co-PMSt)-g-PANI terpolymer was examined in common organic solvents...

Electrical properties of CdS/polyaniline heterojunction

Patidar,D.; Jain,N.; Saxena,N.S.; Sharma,Kananbala; Sharma,T.P.
Fonte: Sociedade Brasileira de Física Publicador: Sociedade Brasileira de Física
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2006 EN
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Conducting polyaniline (PANI) has been synthesized using Sol-gel technique with chemical oxidation process. Chemically prepared cadmium sulphide has been printed on pellet of conducting polyaniline using screen-printing technique. I-V characteristics of conducting polyaniline and CdS printed conducting polyaniline have been recorded at room temperature using Keithley Electrometer. The results indicated that I-V of conducting polyaniline shows non-ohmic behaviour and I-V characteristic of CdS printed PANI, a CdS/ PANI heterojunction, shows the rectification effect and confirms that a diode can be fabricated by using simple technique.

Síntese e caracterização de compósitos polianilina/poli(estireno-co-divinilbenzeno) para Adsorção de Ânions [SnCl4]²-; Synthesis and characterization of composite polyaniline/poly(styrene-co-divinylbenzene)-resin for adsorption of anions [SnCl4]²-

Lima, Wolney Arruda de
Fonte: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Química (IQ); Instituto de Química - IQ (RG) Publicador: Universidade Federal de Goiás; Brasil; UFG; Programa de Pós-graduação em Química (IQ); Instituto de Química - IQ (RG)
Tipo: Dissertação Formato: application/pdf
POR
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In this work were prepared and characterized polyaniline/poly(styrene-co-divinylbenzene) composites by in situ oxidative polymerization of aniline in the pores of styrene-divinylbenzene copolymers. The aim was to obtain composites with high specific surface areas and total pore volumes for use as adsorbents of complex anions [SnCl4]2-. The copolymers with 29 and 84 % of divinylbenzene (DVB) were called PStyDVB 29 and PStyDVB 84, respectively. They were synthesized by suspension polymerization in the presence of inert diluents like toluene and heptane to obtain mesoporous beads with sizes in the range of 400 to 800 μm. Before the oxidative polymerization, the copolymers were swelled with aniline and ethanol mixture at volumetric ratio 20:80. The oxidative polymerization of aniline in the copolymers was carried out using benzoyl peroxide as an oxidant in the presence of hydrochloric or nitric acid as dopant at 25°C in three polymerization cycles. The materials were characterized by infrared spectroscopy with Fourier transform (FTIR), elemental analysis (CNHS), X ray diffraction, thermogravimetry, nitrogen adsorption (specific surface area and pore volume), Scanning Electron Microscopy and Atomic Absorption spectrophotometry. Elemental analysis indicated that the composite doped with HCl adsorb higher amounts of polyaniline (PANI) than using HNO3. The FTIR spectra and X-ray diffraction patterns of the composites were similar to the ones of the copolymers due the low amounts of PANI incorporated. The copolymers had lower thermal stability than composites...

Electrocatalytic oxidation of ethanol on platinum nanoparticles modified polyaniline electrode

Fungaro,D. A.; Oliveira-Neto,A.; Linardi,M.
Fonte: Latin American applied research Publicador: Latin American applied research
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/07/2007 EN
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The electrocatalytic properties of platinum nanoparticles incorporated into polyaniline films was investigated for oxidation of ethanol in sulfuric acid solutions. The electropolymerization of aniline and the electrochemical depositions of plati-num particles into the polyaniline film were achieved by cyclic voltammetry. The effect of the formation conditions of platinum-modified polyaniline films (as cycle numbers, sweep rates) and alcohol concentra-tion were evaluated. The platinum-modified polyani-line films formed by the optimization conditions can be used as a convenient conducting substrate for the ethanol electrooxidation.