Ce travail porte dans un premier temps sur l optimisation du matériau constituant la couche d injection des trous dans les diodes électroluminescentes organiques (OLEDs) et les cellules solaires organiques (OPVCs). Les Polyanilines (PANIs) utilisées dans ce travail sont dispersées dans différents solvants organiques ou dans l'eau. L effet de l épaisseur, de la morphologie et de la conductivité des films de PANI sur l efficacité des cellules solaires a été étudié. Les résultats montrent que la conductivité et l épaisseur des films de PANI affectent énormément l efficacité des dispositifs OLEDs ou OPVCs. Le dopant et le solvant utilisés dans la synthèse de la dispersion de PANI jouent aussi un rôle important. Dans un second temps, différentes PANIs ainsi que des latex de PEDOT et des nanotubes de carbone ont été utilisés seuls en tant qu'électrode dans le but d'accéder à des dispositifs "tout polymère". L influence du pH, de la conductivité, du travail de sortie, la nature du dopant et du solvant sur les propriétés de l injection de charge ont été analysés.

In this thesis, a new technique for using quartz crystal microbalance (QCM) in magnetic field was explored. This technique would take advantage of the sensitive nature of QCM to vibration changes. The idea is to perturb the QCM vibrations with magnetic materials on it by applying magnetic field. A new instrument called magnetic QCM (MQCM) was constructed to explore this technique. The thesis contains three bodies of work. The first body describes the development of the MQCM instrument and the demonstration of the technique. The resonance frequency of a QCM with conducting polymer (polyaniline) suspension in poly(ethylene glycol) was observed to increase with increasing applied DC magnetic field. The change in population of free spins through doping with HCl vapor is reflected in increased frequency-field curve magnitude. The second body of work describes the study of QCM proximity phenomenon discovered during the MQCM instrument development process. When an object approaches a vibrating QCM, the resonant frequency changes. This proximity effect is seen at the distance of 10 mm in air and becomes more pronounced as the distance decreases. This effect depends on the value of quality factor, conductivity of the object, and electrical connection of the object to the QCM electrodes. A simple modified Butterworth van-Dyke model is used to describe this effect. It must be recognized that this effect may lead to experimental artifacts in a variety of analytical QCM applications. The third body of work describes an improved version of MQCM. The complex geometry such as particle suspension were simplified to alternating stack of ferromagnetic and diamagnetic layers. When magnetic field was applied, changes in the QCM admittance magnitude and phase curves were observed. A mass-equivalent stack of continuous consecutive layers of nickel and gold was also exposed to magnetic field but no changes were observed. Butterworth-van-Dyke model attributed the effect to internal shear friction loss among other losses is modulated by the magnetic field. Quantum effect was considered. However, after examining SEM surface images, the source of acoustic response to magnetic field is more likely from interfacial stresses.

Magister Scientiae - MSc / In this research project, nanostructured composites based on Tin dioxide (SnO2) and Titanium dioxide (TiO2) with poly-4-styrene sulfonic acid (PSSA) doped polyaniline (PANI) conducting polymer has been investigated based on their structural, electrical and electrochemical properties. The synthesis of conducting polymers and their metal oxide or composites have been carried out chemically or electrochemically according to methods modified from the literature. Layer-by-layer construction of nano-Metal Oxide/PSSA doped polyaniline composites were successfully constructed by electroanalytical methods on the surface of a glassy carbon working electrode (GCE). / South Africa

Philosophiae Doctor - PhD / In the presented work, immunosensors for detection of Aflatoxin B1 based on different immobilization platforms were studied. Synthesis of an electroactive hydrogel was also carried out. Aflatoxins are a group of mycotoxins that have deleterious effects on humans and are produced during fungal infection of plants or plant products. Electrochemical immunosensor for the determination of Aflatoxin B1 (AFB1) was developed with anti-aflatoxin B1 antibody immobilized on Pt electrodes modified with polyaniline (PANi) and polystyrene sulphonic acid (PSSA). Impedimetric analysis shows that the electron transfer resistances of Pt/PANi-PSSA electrode, Pt/PANi-PSSA/AFB1-Ab immunosensor and Pt/PANi-PSSA/AFB1-Ab incubated in BSA were 0.458, 720 and 1066 kΩ, respectively. These results indicate that electrochemical impedance spectroscopy (EIS) is a suitable method for monitoring the change in electron-transfer resistance associated with the immobilization of the antibody. Modelling of EIS data gave equivalent circuits which showed that the electron transfer resistance increased from 0.458 kΩ for Pt/PANi-PSSA electrode to 1066 kΩ for Pt/PANi-PSSA/AFB1-Ab immunosensor, indicating that immobilization of the antibody and incubation in BSA introduced an electron transfer barrier. The AFB1 immunosensor had a detection limit of 0.1 mg/L and a sensitivity of 869.6 kΩL/mg. / South Africa

Philosophiae Doctor - PhD / In the presented work, immunosensors for detection of Aflatoxin B1 based on different immobilization platforms were studied. Synthesis of an electroactive hydrogel was also carried out. Aflatoxins are a group of mycotoxins that have deleterious effects on humans and are produced during fungal infection of plants or plant products. Electrochemical immunosensor for the determination of Aflatoxin B1 (AFB1) was developed with anti-aflatoxin B1 antibody immobilized on Pt electrodes modified with polyaniline (PANi) and polystyrene sulphonic acid (PSSA). Impedimetric analysis shows that the electron transfer resistances of Pt/PANi-PSSA electrode, Pt/PANi-PSSA/AFB1-Ab immunosensor and Pt/PANi- PSSA/AFB1-Ab incubated in BSA were 0.458, 720 and 1066 kΩ, respectively. These results indicate that electrochemical impedance spectroscopy (EIS) is a suitable method for monitoring the change in electron-transfer resistance associated with the immobilization of the antibody. Modelling of EIS data gave equivalent circuits which showed that the electron transfer resistance increased from 0.458 kΩ for Pt/PANi-PSSA electrode to 1066 kΩ for Pt/PANi- PSSA/AFB1-Ab immunosensor, indicating that immobilization of the antibody and incubation in BSA introduced an electron transfer barrier. The AFB1 immunosensor had a detection limit of 0.1 mg/L and a sensitivity of 869.6 k ΩL/mg. In the second platform an immunosensor based on gold nanoparticles (AuNP) and polythionine-modified glassy carbon electrode (GCE) for the determination of aflatoxin B1 (AFB1) was developed. Aflatoxin B1-BSA conjugate was immobilised on the modified GCE. Horseradish peroxidase (HRP) or Bovine serum albumin (BSA) were used to block sites against non-specific binding of the AFB1- conjugate with other compounds such as the salts used in preparing the buffer when the antibody interacts with the AFB1 conjugate and free AFB1. Competition reaction was allowed to take place between the free AFB1 and AFB1-conjugate for the binding sites of the anti-aflatoxin B1 antibody. Cyclic voltammetry (CV) was employed to characterize the electrochemical properties of the modified process. The peak separation of the immunosensor (ΔEp) was 62 mV indicating a quasi reversible process. Differential pulse voltammetry (DPV) was used to monitor the analytical signal. The response decreased with an increase in AFB1 concentration in the range of 0.6-2.4 ng/mL with a limit of detection of 0.07 and 0.16 ng/mL for HRP and BSA blocked immunosensors respectively. Significantly the low detection limit of 0.07 ng/mL is within the limits set by worl health organization (WHO) for AFB1 and its derivatives which is 2 ng/mL The proposed method eliminates the use of secondary antibody enzymatic labels. Synthesis and characterization of (p-(HEMA)-polyaniline hydrogels were investigated. The hydrogels were synthesized using: 2-Hydroxyeththyl methacrylate (HEMA), N-Tris (hydroxymethyl) methyl] acrylamide, 3- Sulfopropyl methacrylate potassium salt, Tetraethylene glycol diacrylate, Poly-(2- hydroxyethyl methacrylate), 2, 2-Dimethoxy-2-phenylacetophenone and aniline by UV irradiation. Two sets of the hydrogels were prepared using water / 1, 3, 3, 3-(tetramethyl butyl phenyl polyethylene glycol [Triton X-100] and water / ethylene glycol as the solvent. Scanning electron microscopy (SEM) revealed a more uniform pore size when Triton X 100 (TX-100 HG) was used as compared to ethylene glycol (EG-HG). Thermogravimetric analysis (TGA) showed that both hydrogels were stable up to 270 oC. Fourier transform-Infra red (FTIR) spectrum confirmed the incorporation of polyaniline (PANi) and HEMA in the composite. Electrochemical properties of the hydrogels evaluated using Cyclic Voltammetry and Electrochemical Impedance Spectroscopy (EIS) demonstrated the electroactivity and conductivity.

>Magister Scientiae - MSc / The aim of this study was to produce useful composite materials from fly ash, a major waste product of coal combustion from power plants. Polyaniline-fly ash (PANI-FA) composites were prepared by in situ polymerisation of aniline in the presence of Fly Ash (FA) by two slightly different methods. In one case polystyrene sulphonic acid (PSSA) was used as a stabilizer and in another case the starting materials (aniline and FA) were aged before oxidation. The aging procedure formed nanotubes that have cross-sectional diameters of 50-110 nm. The other procedure produced nanotubes with a diameter of 100-500 nm and the length of up to 10μm. The presence of metal oxides and silica in FA were responsible for the formation of nanorods in PANI-PSSA-FA.. The formation of the composites was confirmed by UV-Vis and FTIR. The UV-Vis showed maximum absorbance at 330-360 nm ( due to π-π* transition of benzoid rings) and 600-650 nm(due to charge transfer excitons of quinoid rings), which are characteristics of emaraldine base. The electrochemical analysis of the composites showed that the composites were conductive and electroactive. The Cyclic Voltammetry of PANI-PSSA-FA showed three redox couples which are characteristics of sulphonated PANI. The morphology of the composites was studied by Scanning Electron Microscopy (SEM) and showed that our methods gave composites with improved homogeneity as compared to other reported methods. Thermo Gravimetric analysis (TGA) showed that the presence of FA in the composites improves the thermal stability of the composites by up to 100 0C.

Orientador: Prof. Dr. Wendel Andrade Alves / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2015. / Com o desenvolvimento da nanociencia e nanotecnologia tem sido possivel construir e manipular diferentes materiais na escala nanometrica para as mais diversas aplicacoes como: em medicina, em cosmeticos, dispositivos eletronicos, sensores, biossensores, entre outras. Neste trabalho, apresentamos um estudo baseado na auto-organizacao de micro/nanoestruturas de peptideo (MNTs-FF), via fase solidavapor, sobre um eletrodo de ouro modificado com 4-mercaptopiridina (Au/MCP), visando aplicacao para deteccao de ureia. Estudamos a influencia do solvente no processo de nanoestruturacao do peptideo e observamos que o arranjo estrutural na qual a MNTs se cristaliza interfere fortemente na estabilidade do eletrodo, sendo a estrutura ortorrombica P22121, obtida em vapor de anilina, mais estavel do que a hexagonal P61, em vapor de agua. Essa diferenca estrutural e a chave para o bom desempenho do sensor, porque fornece uma interface contendo sitios de nitrogenio e oxigenio capaz de estabelecer ligacoes com a piridina do substrato (Au) e com os ions amonio e ureia, via interacoes cations ¿Î e ou ligacoes de hidrogenio, apresentando valor de sensibilidade e limite de deteccao para ureia de aproximadamente 81,3 ¿ÊA cm.2 mmol.1 L e 0,06 mmol L-1, respectivamente. A funcionalizacao das MNTs-FF com polianilina e pireno permitiu o ancoramento covalente da enzima urease a superficie do eletrodo Au/MCP/MNTs-FF, com sensibilidade e limite de deteccao frente a deteccao de ureia de 30.0 ¿ÊA cm-2 mmol L-1 e 0.17 mmol L-1 para o eletrodo contendo PANI/Urs, e 4.57 ¿ÊA cm-2 mmol L-1 e 0.15 mmol L-1 para o eletrodo pireno/Urs respecticamente. As MNTs-FF sintetizadas na presenca de nanotubos de carbono (NTc) nao apresentaram alteracao morfologica, porem, estudos de espectroscopia de impedancia eletroquimica (EIE) apontaram uma diminuicao na resistencia a transferencia de carga para o tres sistemas estudados: Au/MCP/MNTs-FF, Au/MCP/NTc/MNTs-FF, Au/MCP/NTc/MNTs-FF/Urs, Rtc 35,0, 0,80, 0,14 k¿¶, respectivamente, apresentando sensibilidade e limite de deteccao frente a deteccao de ureia de 1,5 ¿ÊA cm-2 mmol L-1 e 0,1 mmol L-1 respectivamente. / The development of nanoscience and nanotechnology open up possibilities for the building and construction of distinct materials in the nanometric scale for many different application, such as: in medicine, cosmetics, electronic devices, (bio) sensors, among others. In this work, we presented the self-assembly of peptide micro/nanostructures based in diphenylalanine (MNTs-FF), via solid-vapor phase, on gold electrode modified with 4-mercaptopyridine (Au/MCP), for urea sensing. We studied the influence of the solvent on the peptide self-assembly process, and observed that the structural arrangement in which the MNTs-FF crystallizes strongly influences the electrode stability, the orthorhombic P22121 structure were obtained under aniline vapor, that is more stable than the hexagonal P61 obtained under water vapor interaction. This structural difference is the key to the good sensing performance, because it provides an appropriate interface, containing nitrogen and oxygen sites able to establish bonds with the pyridine, and the ammonium ion or urea molecule, via cation ð interactions and or hydrogen bonds, with the sensitivity and detection limit for the urea sensing of ~ 81.3 ìA cm-2 mmol L-1 and 0.06 mmol L-1, respectively. The functionalization of MNTs-FF with polyaniline and pyrene allowed the covalent anchoring of the enzyme urease the surface of the electrode Au/MCP/MNTs-FF, with sensibility and detection limit for urea sensing of 30.0 ìA cm- 2 mmol L-1 and 0.17 mmol L-1 for the PANI/Urs, and 4.57 ìA cm-2 mmol L-1 and 0.15 mmol L-1 for the pyrene/Urs electrode respectively. The MNTs-FF synthesized in the presence of carbon nanotubes (NTC) showed no morphological change, however, studies of electrochemical impedance spectroscopy (EIS) showed a decrease in charge transfer resistance for the three systems studied, Au/MCP/MNTs-FF, Au/MCP/NTc/MNTs-FF, Au/MCP/NTc/MNTs-FF/Urs, Rtc 35,0, 0,80, 0,14 kÙ, respectively, the sensibility and detection limit for urea detection of 1.5 ìA cm-2 mmol L-1 and 0.1 mmol L-1 respectively.

O estudo da eletro-oxidação de moléculas orgânicas pequenas, altamente energéticas e ecologicamente sustentáveis, tem ganhado importância no cenário tecnológico atual com o desenvolvimento de atuadores e dispositivos eletrônicos biomiméticos. Ao longo das últimas décadas, avanços no entendimento de mecanismos envolvidos na eletrocatálise destas moléculas levaram luz à existência de comportamento auto-organizado durante as reações destas sobre diversos catalisadores metálicos na ausência e presença de um suporte polimérico. Nesse contexto, a reação de eletro-oxidação de glicose é uma candidata interessante como fonte de elétrons em dispositivos eletrônicos, gerando 24 elétrons em sua oxidação total a CO2. Os objetivos desta tese foram, então, investigar a reação de eletro-oxidação da molécula de glicose, com foco na cinética não-linear sobre diferentes superfícies utilizando Pt, Au, Cu, e polianilina (PANI) (como material de suporte do eletrodo de trabalho de Pt) nas oscilações de potencial observadas. Para isso, foram utilizadas técnicas potencio/galvanodinâmicas, potencio/galvanostáticas, Espectroscopia de Impedância Eletroquímica (EIS) e Nanobalança Eletroquímica de Cristal de Quartzo (EQCN). A reação de eletro-oxidação de glicose se mostrou uma rica fonte de oscilações periódicas de potencial (sobre Pt e Au) e de corrente (sobre Au) em meio alcalino, com oscilações periódicas estáveis, de longa duração e em uma ampla região de parâmetros, porém, a fraca adsorção dessa molécula sobre Cu pode ter sido o principal motivo da ausência de instabilidades neste catalisador. A propriedade das oscilações sobre Au e Pt, em meio alcalino, em apresentar altas amplitudes de potencial tem a capacidade de promover a autolimpeza periódica da superfície do catalisador, prolongando o tempo de vida deste e aumentando sua eficiência. Além disso, a sensibilidade das oscilações de potencial a diferentes adsorbatos permitiu o acesso a informações mecanísticas dificilmente obtidas por demais técnicas eletroquímicas. Estudos nanogravimétricos com a EQCN e eletrodos modificados com PANI mostraram que as variações de massa em condições oscilatórias são determinadas majoritariamente pelo fenômeno de compensação de cargas dentro do filme polimérico e que a oxidação da molécula orgânica é responsável pela variação majoritária de carga no mesmo. O aumento na tolerância destes catalisadores em relação à adsorção de CO e outros intermediários e presença de oscilações de potencial mostra uma mudança no mecanismo reacional em eletrocatalisadores de PANI em comparação a Pt e Au. O processo volumétrico, de aumento e diminuição do volume do suporte polimérico durante as oscilações de potencial, pode ser considerado no edesigne de atuadores auto-oscilantes em dispositivos autônomos. Por fim, a investigação da cinética não-linear na reação de eletro-oxidação de glicose sobre Au foi relatada por este trabalho pela primeira vez na literatura. / The study of the electro-oxidation of small organic molecules, highly energetic and ecologically sustainable, has gained importance in the current technological scenario with the development of actuators and biomimetic electronic devices. Over the last decades, advances in the understanding of the mechanisms involved in the electrocatalysis of these molecules have led light to the existence of self-organized behavior during their reactions on several metal catalysts and metal-polymer composites. More recently, new research has shown that such a phenomenon can be used in the control of the poisoning of catalytic surfaces by self-cleaning the surface, using such oscillatory reactions, increasing the catalyst life time and the potency of practical devices. In this context, the electro-oxidation reaction of glucose is na interesting candidate as electron source in electronic devices, despite the difficulty in its total oxidation, generating 24 electrons in its complete oxidation to CO2. The objectives of this thesis were to investigate the electro-oxidation reaction of the glucose molecule, focusing on the non-linear kinetics on different catalyst surfaces used (Pt, Au and Cu) and the effect of the support for working electrode on potential oscillations. For this, potentio/galvanodynamic, potentio/galvanostatic, Electrochemical Impedance Spectroscopy (EIS) and Electrochemical Quartz Crystal Nanobalance (EQCN) techniques were used. The electro-oxidation reaction of glucose was shown to be a rich source of periodic potential oscillations (over Pt and Au) and of current (over Au) in alkaline medium, with stable periodic oscillations of long duration and in a wide range of parameters, but the low adsorption of this molecule on Cu may have been the main reason for the absence of instabilities in this catalyst. In contrast to the high current densities observed for the oxidation of glucose in alkaline medium over Pt and Au, in acid medium the low glucose activity led to low current densities over Pt and unstable potential oscillations in a more constrained range of parameters. In addition, the nonlinear kinetics of the electro-oxidation reaction of glucose on Au was reported by this work for the first time in the literature. Nanogravimetric studies with EQCN with polyaniline-modified electrodes have shown that the potential oscillations during the electro-oxidation of formic acid are strongly influenced by the process of charge compensation in the polymer film, for both the electrode of Pt coated with PANI (Pt/PANI) and for Pt nanoparticles deposited in this polymer support (Au/PANI/Pt). However, the decrease in the potential values where oscillations are observed and the decrease in their frequency can be explained by the increase in the tolerance of the Pt nanoparticles to the adsorption of CO and other intermediates, as reported by several authors in the literature. And in Pt nanoparticle electrodes supported by films such as PANI, the charge variation is still dominated by the organic oxidation reaction and the mass variation in the surface of the catalyst is dominated by the charge compensation effect within the film. Thus, the decrease of the catalyst affinity by organic adsorption makes the dynamic instabilities kinetics slower, as observed for the Pt, Au and PANIbased electrodes. And the higher tolerance of the catalyst supported on the polymer electrode by strong adsorbates, such as CO, does not prevent the emergence of oscillatory behavior, however, it can direct the oxidation reaction of the organic by a different mechanism pathway.

Submitted by Milena Rubi (milenarubi@ufscar.br) on 2016-11-03T14:15:07Z No. of bitstreams: 1 SANTOS_Fabio_2015.pdf: 7866329 bytes, checksum: ae986dab3375f6b5f2e34e0b103331dd (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2016-11-03T14:15:20Z (GMT) No. of bitstreams: 1 SANTOS_Fabio_2015.pdf: 7866329 bytes, checksum: ae986dab3375f6b5f2e34e0b103331dd (MD5) / Approved for entry into archive by Milena Rubi (milenarubi@ufscar.br) on 2016-11-03T14:15:28Z (GMT) No. of bitstreams: 1 SANTOS_Fabio_2015.pdf: 7866329 bytes, checksum: ae986dab3375f6b5f2e34e0b103331dd (MD5) / Made available in DSpace on 2016-11-03T14:15:39Z (GMT). No. of bitstreams: 1 SANTOS_Fabio_2015.pdf: 7866329 bytes, checksum: ae986dab3375f6b5f2e34e0b103331dd (MD5) Previous issue date: 2015-04-17 / Não recebi financiamento / This work involves the construction of a portable equipment device for electrochemical polymerization of an Intrinsically Conductive Polymer - PIC. Using a rotary circular electrode, this method’all allows the production of various polymers especialy PIC's parameterize, controlling and monitoring all the process, so that a polymer can be prepared with maximum efficiency. As it is a portable equipment, it is possible to share with the universities labs and research centers that are working with conductive polymers and or other tips of polymers with can be inter interested in electrochemical synthesis. Using this method, you can ensuring the well contours specified parameters, the produced quantity for the preparation of the tests are larger, allowing a better characterization of the samples and production of products. The studied Conductive Polymer for the qualification of portable equipment was Polyaniline "PAni", this was characterized by the Fourier transform infrared region - FTIR, scanning electron microscopy – SEM, spectroscopy ultraviolet and Visible - UVVIS, thermogravimetric analysis – TGA, analysis by cyclic voltammetric and conductivity volumetric by the method at two tips. / Este trabalho consiste na construção de um equipamento portátil para polimerização eletroquímica de um Polímero Intrinsecamente Condutor - PIC. Utilizando-se de um eletrodo circular rotativo, esse método permitirá a produção de diversos polímeros em especiais os PIC’s, parametrizando, controlando e monitorando todo o processo, de forma que possa ser elaborado um polímero com máxima eficiência. Por se tratar de um equipamento portátil, acredita-se que possa ser difundido entre os laboratórios de demais universidades e centros de pesquisas que estão trabalhando com polímeros condutores e/ou outra classe de polímeros que possuem interesse na síntese eletroquímica. Com esse método, além de garantir os parâmetros de contornos bem especificados, a quantidade produzida para elaboração dos ensaios são maiores, permitindo uma melhor caracterização das amostras e na produção de produtos. O Polímero Condutor estudado, para a qualificação do equipamento portátil foi a Polianilina “PAni”, este foi caracterizado através das técnicas de espectroscopia na região de infravermelho com transformada de Fourier - FTIR, microscopia eletrônica de varredura – MEV, espectroscopia na região do ultravioleta e visível – UV-VIS, análise termogravimétrica – TGA, análise por voltametria cíclica, e condutividade elétrica volumétrica pelo método de duas pontas.

Este trabalho apresenta um estudo sobre a morfologia de filmes finos de polianilina, fabricados por diferentes processos e depositados sobre diferentes substratos pela técnica de microscopia de força atômica (AFM). Os processos usados para a fabricação dos filmes foram o de espalhamento fluido, o de centrifugação, o de auto montagem e o eletroquímico. Os substratos usados foram: vidro, ouro/cromo/vidro, quartzo, ITO, silício e mica. Além da análise visual da qualidade dos filmes, ou seja, do grau de recobrimento do substrato e da uniformidade dos filmes, foram feitas análises de parâmetros quantitativos através de medidas de rugosidade. Usando modelos de crescimento como o de deposição balística e de análise de rugosidade, como o da densidade do espectro de potência, (transformada de Fourier da rugosidade da imagem em função da freqüência espectral) em superfícies auto-afins, foram obtidos parâmetros como: expoente de rugosidade, comprimento característico de correlação e dimensão fractal. Apesar dos filmes de polianilina serem sistemas extremamente complexos, - compostos de macromoléculas formando uma estrutura semicristalina - os parâmetros obtidos por esses modelos, que foram elaborados para sistemas bem mais simples, deram resultados muito bons e auto-coerentes. Como conclusão, mostramos que a conjuminação da técnica de microscopia de força atômica com esses modelos compõem um método poderoso para o estudo de filmes finos orgânicos. / This work presents a detailed study about the characteristic of thin films of polyaniline, fabricated by different methods and deposited over different substrates using Atomic Force Microscopy technique (AFM). The processes used for film depositions were casting, spin-coating, self-assembly, and the electrochemistry methods. The substrata used were: glass plates, gold/chromium/glass, quartz, ITO, silicon, and mica. Besides the visual analysis, that observes the film uniformity and verifies the coating degree of the substratum, the application of some mathematical models was employed to obtain quantitative parameters about the roughness of the film surfaces. From the ballistic deposition model, developed to explain growing processes, and the power spectrum density that takes the Fourier transform of the roughness in function of the spectral frequency, both developed for self-affine surfaces, it was obtained parameters as: the roughness exponent, the correlation characteristic length, and the fractal dimension. Despite the highly complex structure of the polyaniline - composed by macromolecules forming a semicrystalline structure- the obtained parameters by such models developed for very simple systems, provided reasonable and self-coherent results. As a final result of this work we showed that the synergy between the AFM technique and the above mentioned models compose a powerful method for the study of thin organic films.