In this research,we used the electrochemical (cyclic voltammetry) method to synthesize (polyaniline) PANI thin film on the top of ITO substrate which applied extensively on polymer organic light emitting diodes based on ITO (170nm) / PANI (55nm ) / PFG(60 nm )/LiF(1nm)/Ca(10nm) / Al (200nm) . The PANI thin films have excellent optical and electric properties. According to the measurement results of ultraviolet visible spectrophotometry, the PANI thin films with different aniline monomer concentrations display the absorption peak at the range of 500nm to 600nm and have high light transmission near 90%. The conductivity of PANI thin film (2.02x10-2(s/cm)) is higher than that of PEDOT:PSS thin film (1.28x10-2(s/cm)). The highest occupied molecular orbital value of PANI thin film is about 5.0 eV that close to PEDOT:PSS thin film. Therefore, it is suitable act as hole transporting layer. In this study, we can control the surface morphology of PANI thin film by exchanging synthesized parameters. Finally, we have fabricated a PLED device with PANI as a hole transporting layer by electrochemical synthesis with at the aniline monomer concentration of 0.3M and the scan rate of 0.0.1 V/s. The device exhibits a maximum luminance of 10500 cd/m2 at 15 V and power efficiency of 0.25 lm/W at 10V.

In our works , we used P3HT and PCBM blended in xylene as donor and acceptor materials for polymer solar cells . For the standard devices with the configuration of ITO/PEDOT/P3HT¡GPCBM/Al , the power conversion efficiency of 2.3% is achieved under AM1.5 100 mW/cm2 illumination . In order to enhance the hole transportation , we used PANi nanotube , which has high conductivity , as an anode interlayer between the PEDOT¡GPSS layer and the organic active layer . The device structure was ITO/PEDOT/PANi/P3HT:PCBM/Al , and the power conversion efficiency increased from 2.3% to 2.6% . The efficiency of polymer solar cell was also increased with different rpm by using spin-coating process . For devices , at the process parameters under 4000rpm and 100Å thickness of PANi , the power conversion efficiency was 60% higher than that of standard device . We suggested that PANi can act as a good anode interlayer material for polymer solar cells .

Recently, a variety of conducting polymer have great potentials for practical utility. Among these polymers, polyaniline (polyaniline,PANI) has the widest applications . Using electrochemical synthesis to fabricate Aniline copolymer has several kind of advantages (i) Aniline is cheap and easy to polymerize¡F (ii) High stability¡F(iii) The conductivity of the polymer can be modulated¡F(iv) The thickness of PANI film can be controlled. In conclusion, it is quite useful to apply the PANI into polymer solar cells as the hole transporting layer. We used Cyclic Voltammetry to grow the PANI thin film. Then, we investigated the performance of the device affected by morphology with different sweep rate and the difference of electric characteristic and transmission between PEDOT and PANI. P3HT was used as a donor material because of its high stability and high absorption in visible light. PCBM was used as a acceptor material because of its high stability and high electron transportation. The device was constructed of ITO (150 nm) / PANI (50 nm) / P3HT:PCBM (100 nm) / Al (200 nm). When the sweep speed is lower, the particle of PANI thin film is closer and its scale size is more similar. When the sweep rate is 0.01 V/s, PANI thin film would grow about 80 nm, and the power conversion efficiency of 1.83% was achieved under AM1.5G 100mW/cm2 illumination.

Made available in DSpace on 2014-06-12T23:13:25Z (GMT). No. of bitstreams: 2 arquivo2846_1.pdf: 9900470 bytes, checksum: 8e27fa0d6a4997e6d5a15d66fdcd42bf (MD5) license.txt: 1748 bytes, checksum: 8a4605be74aa9ea9d79846c1fba20a33 (MD5) Previous issue date: 2011 / Conselho Nacional de Desenvolvimento Científico e Tecnológico / Polianilina (PANI), na forma de sal de esmeraldina, e compósitos de polianilina e prata (PANI/Ag) foram sintetizados por via não convencional, utilizando-se radiação ionizantes (raios X e γ), ultravioleta e ultrassom, em lugar de oxidantes químicos ou eletroquímicos normalmente empregados na síntese da PANI. Nos dois primeiros processos, fótons de média e alta energia interagem com solução aquosa ácida de anilina, íons Ag+ e NO3 -, e desencadeiam o processo de polimerização, enquanto que no último processo, as altas temperaturas e altas pressões geradas pela implosão de cavidades produzidas pela interação de ondas ultra sônicas com a solução, induz a formação de radicais, que são responsáveis pela polimerização do monômero. O mecanismo de polimerização da anilina em todos os casos foi investigado utilizando substâncias seqüestradoras de radicais (tais como, DMSO e álcool isopropílico). Estes resultados indicam fortemente que radicais hidroxila (∙OH) gerados in situ durante a exposição seriam os principais agentes responsáveis pela polimerização do monômero, enquanto que ∙H, dímeros, tetrâmeros e oligômeros de anilina agiriam como redutores dos íons de Ag+. Os produtos sintetizados foram caracterizados por espectroscopia na região do UV-Vis e infravermelho, difratometria de raios X, termogravimetria e análise elementar. A caracterização morfológica dos produtos foi realizada por microscopia eletrônica de varredura, e a condutividade elétrica medida pelo método quatro pontas. O desenvolvimento da rota de síntese com ultrassom possibilitou a preparação de nanofibras e fios de Ag e o desenvolvimento de um novo método para a síntese de PANI alquiladas a partir de derivados de anilina com impedimento estérico. As nanofibras e os fios de prata foram obtidos adicionando-se álcool isopropílico a uma solução aquosa contendo anilina e nitrato de prata; neste caso o álcool tem a função de reduzir a cinética de polimerização e permitir a formação de uma dispersão estável do compósito que, por sua vez, favorece o crescimento lento das fibras e permite a obtenção de fibras com diâmetro e comprimentos médios controlados. As PANI alquiladas foram obtidas saturando-se, com NaCl, soluções aquosas de N-metil-anilina e N-isopropil-anilina contendo íons NO3 -1. Outra aplicação da metodologia desenvolvida com radiação ionizante possibilitou a obtenção de híbridos de polifosfato de alumínio e polianilina (AlPP/PANI) e de vidro e polianilina

Polyaniline (PANI), when doped with small-molecule acids, is an attractive candidate for organic and polymer electronics because of its high electrical conductivity. Its utility as functional components in electrical devices, however, has been severely restricted because such PANI has limited processibility stemming from its limited solubility in common solvents. To overcome this barrier, we have developed water dispersible PANI that is template polymerized in the presence of a polymer acid, poly(2-acrylamido-2-methyl-1-propanesulfonic acid), or PAAMPSA. The polymer acid serves two roles: it acts as a dopant to render PANI conductive and excess water soluble pendant groups provide dispersibility of PANI in aqueous media. While the introduction of polymer acids renders the conducting polymer processible, such gain in processibility is often accompanied by a significant reduction in conductivity. As such, PANI that is doped with polymer acids has only seen limited utility in organic electronics. Given the promise of conducting polymers in organic electronics in general, this thesis focuses on the elucidation of processing-structure-property relationships of PANI-PAAMPSA with the aim of ultimately improving the electrical conductivity of polymer acid-doped PANI. By controlling the molecular weight and molecular weight distribution of the polymer acid template, we have improved the conductivity of PANI-PAAMPSA from 0.4 to 2.5 S/cm. The conductivity increases with decreasing molecular weight of PAAMPSA, and it further increases with narrowing the molecular weight distribution of PAAMPSA. Strong correlations between the structure and the conductivity of PANI-PAAMPSA are observed. In particular, the crystallinity of PANI increases with increasing the conductivity of PANI-PAAMPSA. Given that the crystallinity qualifies the molecular order in PANI-PAAMPSA, we observe a linear correlation between molecular order and macroscopic charge transport in PANI-PAAMPSA. PANI-PAAMPSA forms electrostatically stabilized sub-micron particles during polymerization due to strong ionic interactions between the sulfonic acid groups of PAAMPSA and aniline. When cast as films, the connectivity of these particles must play an important role in macroscopic conduction. The size and size distribution of PANI-PAAMPSA particles is strongly influenced by the molecular characteristics of polymer acid template. Templating the synthesis of PANI-PAAMPSA with a higher molecular weight PAAMPSA results in larger particles, and templating with a PAAMPSA having a larger molecular weight distribution results in a large size distribution in the particles. Because conduction in PANI-PAAMPSA films is governed by how these particles pack, the macroscopic conductivity of PANI-PAAMPSA films increases with increasing particle density, that is reducible from the molecular characteristics of PAAMPSA. Moreover, PANI-PAAMPSA particles are structurally and chemically inhomogeneous. The conductive portions of the polymer preferentially segregate to the particle surface. Conduction in these materials is therefore mediated by the particle surface and conductivity thus scales superlinearly with particle surface area per unit film volume. We further have improved the electrical conductivity of PANI-PAAMPSA by more than two orders of magnitude via post-processing solvent annealing with dichloroacetic acid (DCA). Since DCA is a good plasticizer for PAAMPSA and its pKa is lower than that of PAAMPSA (pKas of DCA and PAAMPSA are 1.21 and 2.41, respectively, at room temperature), DCA can effectively moderate the ionic interactions between PANI and PAAMPSA, thereby relaxing the sub-micron particulate structure arrested during polymerization. PANI-PAAMPSA can thus rearrange from a “compact coil” to an “extended chain” conformation upon exposure to DCA. Efficient charge transport is thus enabled through such “extended chain” PANI-PAAMPSA structure. DCA-treated PANI-PAAMPSA exhibits an average conductivity of 48 S/cm. The DCA treatment is not only specific to PANI-PAAMPSA. This treatment can also enhance the conductivity of commercially-available poly(ethylene dioxythiophene) that is doped with poly(styrene sulfonic acid), or PEDOT-PSS. Specifically, DCA-treated PEDOT-PSS exhibits a conductivity of 600 S/cm; this conductivity is the highest among polymer acid-doped conducting polymers reported so far. PANI-PAAMPSA can effectively function as anodes in organic solar cells (OSCs) whose active layer is a blend of poly(3-hexylthiophene), P3HT, and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). Specifically, the OSCs with PANI-PAAMPSA anodes exhibit an average short circuit current density of 1.95 mA/cm², open circuit voltage of 0.52 V, fill factor of 0.38, and efficiency of 0.39 %. The use of DCA-treated PANI-PAAMPSA as anodes increases device performance (i.e., short circuit current density and thereby efficiency) of OSCs by approximately two and a half fold. The OSCs with DCA-treated PANI-PAAMPSA anodes exhibit short circuit current density and efficiency as high as 4.95 mA/cm² and 0.97 %, respectively. We demonstrated several factors that govern the electrical conductivity of polymer acid-doped conducting polymers. Design rules, such as those illustrated in this study, can enable the development of conducting polymers that is not only easily processible from aqueous dispersions, but also sufficiently conductive for electronic applications, and should bring us closer to the realization of low-cost organic and polymeric electronics. / text

This research is to synthesize polyaniline (PANI) thin film on the Poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) by using potentiostatic deposition of electrochemical method. The hybrid film composed of PEDOT:PSS and PANI was fabricated to replace the ITO layer for polymer solar cells as an anode. In the future, the hybrid film can develop the flexible polymer solar cells. In this study, we fixed the total thickness of the hybrid film, and we investigated optical transmittance, conductivity, Highest Occupied Molecular Orbital (HOMO), surface roughness, and surface morphology of hybrid films by changing the ratio of PEDOT:PSS and PANI, and to discuss the factors on device efficiency. Then, we compared the device structures with anode made by PEDOT: PSS. We found the hybrid films fabricated with different ratio of PEDOT:PSS and PANI, and the HOMO results were similar. In addition, we found optical transmittance, conductivity, surface roughness, and surface morphology of hybrid films that varies with different ratio of PEDOT:PSS and PANI. The power conversion efficiencies of the device mainly were affected by the surface roughness and morphology of the hybrid film surface. Comparing to other parameters, the hybrid film fabricated by PEDOOT:PSS(280nm) and PANI(30nm) owns the most appropriate surface roughness and surface morphology. The power conversion efficiency(PCE) was up to 0.68%, and then via post-annealing of 90¢J 10 minutes the PCE was increase to 1.06% under AM 1.5G illumination based on PEDOT:PSS (280 nm) / PANI (30 nm) / P3HT: PCBM (100 nm) / Al (200 nm), and the device area of 0.16 cm2.

Um método amplamente utilizado na proteção contra a corrosão de ligas de alumínio é a formação de camadas de conversão de cromo. Na busca de métodos \"ambientalmente amigáveis\" de proteção contra corrosão existe a possibilidade da utilização de polímeros condutores, como a polianilina (PAni), que pode atuar por efeito barreira, assim como pela absorção de cargas provenientes da solução e / ou camadas auto-organizadas (SAM, do inglês \"self assembled monolayers\"), onde a proteção pode ocorrer de forma indireta, quando a SAM atua como promotora de adesão para outros revestimentos ou de forma direta, quando a própria monocamada bloqueia o acesso de substâncias responsáveis pela corrosão, à superfície protegida. Neste trabalho é proposta a utilização de bi-camadas baseadas de propil-trimetóxi-silano (PTMS) + PAni e octadecil-trimetóxi-silano (ODTMS) + PAni para a proteção contra a corrosão das ligas de alumínio AA1050, AA2024 e AA7075. Para os ensaios de corrosão foram utilizadas as técnicas de potencial de circuito aberto, curvas de polarização potenciodinâmica e espectroscopia de impedância eletroquímica. Análise de microscopia óptica e microscopia eletrônica de varredura (MEV) foram realizadas antes e após os ensaios de corrosão para verificar a eficiência de proteção contra corrosão dos revestimentos propostos. Adicionalmente foram realizados testes de névoa salina e aderência, além da caracterização das ligas por MEV e espectroscopia de energia dispersiva de raios X (EDX). Os resultados obtidos demonstram que os tratamentos utilizados resultaram em melhoras na resistência contra a corrosão na seguinte ordem: PTMS < ODTMS < PAni < PTMS + PAni < ODTMS + PAni, sendo que este último o que apresenta os melhores resultados como maiores deslocamentos do Ecorr para valores mais positivos, diminuição da icorr, menor número de pontos de corrosão após a realização das curvas de polarização, maiores valores de impedância total em todo o intervalo de frequência utilizado e maior resistência à exposição à névoa salina. / A method widely used in corrosion protection of aluminum alloys is the formation of conversion layers of chromium. In search of \"environmentally friendly\" corrosion protection methods there is the possibility of using conducting polymers such as polyaniline (PAni), which can act by barrier effect or absorbing charged particles from the solution and / or self-assembled monolayers (SAM), where protection may occur indirectly, when the SAM acts as a promoter of adhesion to other coatings, or directly, when the monolayer blocks the access of aggressive substances to the surface. This work proposes the use of bi-layers based on propyl-trimethoxy-silane (PTMS) + PAni and octadecyl-trimethoxy-silane (ODTMS) + PAni for corrosion protection of aluminum alloys AA1050, AA2024 and AA7075. For the corrosion tests were used different techniques such as: open circuit potential, potentiodynamic polarization curves and electrochemical impedance spectroscopy. Analysis of optical microscopy and scanning electron microscopy (SEM) were performed before and after the corrosion tests in order to verify the efficiency of the proposed coatings in corrosion protection. Additionally, tests of salt spray and adhesion were made, in addition to the characterization of the alloys by SEM and X-ray dispersive energy. The results show that the treatments resulted in improvements in corrosion resistance in the following order: PTMS < ODTMS < PAni < PTMs + PAni < ODTMS + PAni. The last one gives the best results such as larger shifts of the Ecorr to more positive values, decrease of the icorr, fewer corrosion points after the polarization curves, higher values of total impedance in the entire range of frequency used and more resistant to the exposure to salt spray.

Neste trabalho foram estudadas soldas TIG (Tungsten Inert Gas) nos aços inoxidáveis 304 e 316, e no aço carbono 1020. As alterações das microestruturas foram investigadas por microscopias óptica (MO) e eletrônica de varredura (MEV), enquanto que a corrosão destas regiões foi estudada por análises de polarização potenciodinâmica. Um sistema miniaturizado de análise corrosão, denominado sensor pontual de corrosão (SPC), foi utilizado com o objetivo de analisar a estreita região dos cordões de solda, estudando assim a influência da corrente de solda na corrosão desta região nos aços inoxidáveis 304 e 316. Os resultados mostraram que a alteração da estrutura cristalina na solda tornou esta região menos susceptível à corrosão que o material base, e o aumento da corrente de solda intensificou ainda mais este efeito, pela formação de estruturas mais compactas. No caso do aço carbono 1020 (mais susceptível à corrosão), o estudo da corrosão de sua solda foi feito utilizando técnicas eletroquímicas globais (potencial de circuito aberto, PCA, e espectroscopia de impedância eletroquímica, EIE) e técnicas de corrosão localizadas (espectroscopia de impedância eletroquímica localizada, EIEL, e técnica do eletrodo vibratório de varredura, TEVV). Para proteção contra a corrosão do aço inoxidável e suas soldas, foi utilizado um revestimento de polianilina (PAni) na forma de base esmeraldina; análises de polarização potenciodinâmica mostraram a eficiência deste revestimento protetor. Para o aço carbono 1020, devido à sua maior facilidade de oxidação, foi sintetizado um revestimento protetor a base de PAni e nanotubos de TiO2 (PAni/n-TiO2). As variáveis estudadas na síntese do polímero foram: temperatura de síntese, meio reacional, grau de dopagem do polímero (condutor ou isolante) e número de camadas. Os polímeros e compósitos foram caracterizados por espectroscopias nas regiões do ultravioleta-visível (UV-vis) e infravermelho (IV), MEV e espectroscopia de energia dispersiva de raios-X (EDX). Os aços recobertos com os filmes foram analisados por MO e MEV, EDX, e por ensaios eletroquímicos de polarização potenciodinâmica, PCA e resistência de polarização, além de ensaio de corrosão acelerada em câmara de névoa salina. As melhores condições encontradas foi para o revestimento de PAni/n-TiO2 desdopado (base esmeraldina) sintetizado a 25&deg;C em meio de H2SO4, e com 3 camadas; o n-TiO2 apresentou um efeito de aumento da aderência do filme ao substrato metálico. / In this work TIG (Tungsten Inert Gas) welds have been studied in the 304 and 316 stainless steels, and in the 1020 carbon steel. The changes in the microstructure were investigated by optical microscope (OM) and scanning electronic microscope (SEM), and the corrosion behavior in these zones were studied by potentiodynamic polarization analysis. A miniaturized corrosion analysis device, named corrosion punctual sensor, has been used to analyze the close weld bead, researching for the influence of the weld current in the corrosion process in this zone of the 304 and 316 stainless steels. The results showed that the change in the crystalline structure of the weld zone became this region less susceptible to corrosion process than their base material, and the increase in the weld current intensified this effect, by the formation of more compact structures. In the case of the 1020 carbon steel (more susceptible to corrosion processes), the corrosion in its weld zone was researched by global (like open potential circuit, OCP, and electrochemical impedance spectroscopy, EIS) and localized (like localized electrochemical impedance spectroscopy, LEIS, and scanning vibrating electrode technique, SVET) electrochemical techniques. For protecting stainless steels and their weld zones against corrosion processes, a polyaniline (PAni) coating in the emeraldine base form was used; potentiodynamic polarization analysis showed the efficiency of this protective coating. For the 1020 carbon steel, due to its mayor oxidation susceptibly, a protective coating of PAni and TiO2 nanotubes (PAni/n-TiO2) was synthesized. The variables researched were: synthesis temperature, reaction medium, degree of doping of the polymer (conductor or insulator) and number of layers. The polymers and composites were characterized by ultraviolet visible (UV-vis) and infrared spectroscopies, SEM and Energy Dispersive X-Ray Spectroscopy (EDX). The coated steels were analyzed by OM, MEV and EDX spectroscopies, and by potentiodynamic polarization, OCP and polarization resistance electrochemical measurements, besides accelerate corrosion tests in a salt spray chamber. The best conditions found for the dedoped PAni/n-TiO2 coatings (emeraldine base) were: temperature of synthesis of 25&deg;C, H2SO4 as reaction medium, and with 3 layers; n-TiO2 has presented an effect of increasing the adherence of the coating with the steel.

Neste trabalho foram estudadas soldas TIG (Tungsten Inert Gas) nos aços inoxidáveis 304 e 316, e no aço carbono 1020. As alterações das microestruturas foram investigadas por microscopias óptica (MO) e eletrônica de varredura (MEV), enquanto que a corrosão destas regiões foi estudada por análises de polarização potenciodinâmica. Um sistema miniaturizado de análise corrosão, denominado sensor pontual de corrosão (SPC), foi utilizado com o objetivo de analisar a estreita região dos cordões de solda, estudando assim a influência da corrente de solda na corrosão desta região nos aços inoxidáveis 304 e 316. Os resultados mostraram que a alteração da estrutura cristalina na solda tornou esta região menos susceptível à corrosão que o material base, e o aumento da corrente de solda intensificou ainda mais este efeito, pela formação de estruturas mais compactas. No caso do aço carbono 1020 (mais susceptível à corrosão), o estudo da corrosão de sua solda foi feito utilizando técnicas eletroquímicas globais (potencial de circuito aberto, PCA, e espectroscopia de impedância eletroquímica, EIE) e técnicas de corrosão localizadas (espectroscopia de impedância eletroquímica localizada, EIEL, e técnica do eletrodo vibratório de varredura, TEVV). Para proteção contra a corrosão do aço inoxidável e suas soldas, foi utilizado um revestimento de polianilina (PAni) na forma de base esmeraldina; análises de polarização potenciodinâmica mostraram a eficiência deste revestimento protetor. Para o aço carbono 1020, devido à sua maior facilidade de oxidação, foi sintetizado um revestimento protetor a base de PAni e nanotubos de TiO2 (PAni/n-TiO2). As variáveis estudadas na síntese do polímero foram: temperatura de síntese, meio reacional, grau de dopagem do polímero (condutor ou isolante) e número de camadas. Os polímeros e compósitos foram caracterizados por espectroscopias nas regiões do ultravioleta-visível (UV-vis) e infravermelho (IV), MEV e espectroscopia de energia dispersiva de raios-X (EDX). Os aços recobertos com os filmes foram analisados por MO e MEV, EDX, e por ensaios eletroquímicos de polarização potenciodinâmica, PCA e resistência de polarização, além de ensaio de corrosão acelerada em câmara de névoa salina. As melhores condições encontradas foi para o revestimento de PAni/n-TiO2 desdopado (base esmeraldina) sintetizado a 25&deg;C em meio de H2SO4, e com 3 camadas; o n-TiO2 apresentou um efeito de aumento da aderência do filme ao substrato metálico. / In this work TIG (Tungsten Inert Gas) welds have been studied in the 304 and 316 stainless steels, and in the 1020 carbon steel. The changes in the microstructure were investigated by optical microscope (OM) and scanning electronic microscope (SEM), and the corrosion behavior in these zones were studied by potentiodynamic polarization analysis. A miniaturized corrosion analysis device, named corrosion punctual sensor, has been used to analyze the close weld bead, researching for the influence of the weld current in the corrosion process in this zone of the 304 and 316 stainless steels. The results showed that the change in the crystalline structure of the weld zone became this region less susceptible to corrosion process than their base material, and the increase in the weld current intensified this effect, by the formation of more compact structures. In the case of the 1020 carbon steel (more susceptible to corrosion processes), the corrosion in its weld zone was researched by global (like open potential circuit, OCP, and electrochemical impedance spectroscopy, EIS) and localized (like localized electrochemical impedance spectroscopy, LEIS, and scanning vibrating electrode technique, SVET) electrochemical techniques. For protecting stainless steels and their weld zones against corrosion processes, a polyaniline (PAni) coating in the emeraldine base form was used; potentiodynamic polarization analysis showed the efficiency of this protective coating. For the 1020 carbon steel, due to its mayor oxidation susceptibly, a protective coating of PAni and TiO2 nanotubes (PAni/n-TiO2) was synthesized. The variables researched were: synthesis temperature, reaction medium, degree of doping of the polymer (conductor or insulator) and number of layers. The polymers and composites were characterized by ultraviolet visible (UV-vis) and infrared spectroscopies, SEM and Energy Dispersive X-Ray Spectroscopy (EDX). The coated steels were analyzed by OM, MEV and EDX spectroscopies, and by potentiodynamic polarization, OCP and polarization resistance electrochemical measurements, besides accelerate corrosion tests in a salt spray chamber. The best conditions found for the dedoped PAni/n-TiO2 coatings (emeraldine base) were: temperature of synthesis of 25&deg;C, H2SO4 as reaction medium, and with 3 layers; n-TiO2 has presented an effect of increasing the adherence of the coating with the steel.

A obtenção de blendas condutoras a base de água, ainda é pouco explorada e apresenta uma interessante alternativa ao uso de compostos poluentes como os cromatos na proteção à corrosão metálica. Os polímeros condutores apresentam propriedades anti-corrosivas e podem ser processados em meio aquoso, eliminando o uso de solventes orgânicos altamente tóxicos e agressivos para o meio ambiente. O presente trabalho consiste no estudo da proteção da corrosão metálica por revestimento de filmes de blendas contendo Poli(anilina) (PANI). As blendas foram obtidas à partir da mistura de uma suspensão aquosa de PANI com uma dispersão aquosa de Poli(metil metacrilato). O uso de técnicas como potencial zeta, espalhamento de luz dinâmico, análise térmica e microscopia eletrônica de varredura permitiram a caracterização da mistura homogênea obtida. Medidas através do método da sonda de quatro pontas mostraram que as blendas apresentam condutividade mesmo com baixas quantidades de PANI e a técnica de espectroscopia Raman mostrou a presença da forma condutora deste polímero nos filmes das blendas. Técnicas como microscopia óptica, potencial a circuito aberto, voltametria linear e espectroscopia de impedância eletroquímica permitiram avaliar a proteção à corrosão de eletrodos metálicos de ferro, cobre e níquel recobertos com filmes das blendas de PANI em diferentes meios corrosivos. As blendas mostraram eficiência contra a corrosão e apresentam-se como um novo material não poluente para a proteção à corrosão metálica. / The development of water-based conducting blends has not yet been very much explored and it presents itself as an interesting alternative to the use of polluting compounds such as chromates in the protection of metals from corrosion. The conducting polymers present anti-corrosion properties and can be processed in aqueous medium, eliminating the use of organic solvents, which are highly toxic and threatening to the environment. This thesis is based on the study of protection from metallic corrosion using poly(aniline) (PANI) coating blends. The blends have been obtained by mixing a PANI aqueous suspension with a poly(methyl metacrylate) aqueous dispersion. Techniques such as zeta potential, dynamic light scattering, thermal analysis and scanning electronic microscopy allowed the characterization of the homogeneous mixture obtained. Measurements carried out by the four-point probe method showed that the blends present conductivity even despite low PANI quantities. In addition, the Raman spectroscopy technique showed the presence of the conducting form of this polymer on the blend films. Techniques such as optical microscopy, open-circuit potential, linear voltammetry and impedance spectroscopy allowed the evaluation of the corrosion protection of the iron, copper, and nickel metallic electrodes coated with PANI blend films in different corrosives mediums. The blends showed efficiency against corrosion and they are therefore a new environmentally friendly material for metallic corrosion protection.