AGRADECIMENTOSAo meu grande amigo, orientador e mentor Adnei Melges de Andrade que trilhou meu caminho na gostosa arte do saber. Obrigado pelo grande apoio, incentivo, atenção e solidariedade não só nesse trabalho como em minha vida.Ao meu co-orientador Bart M. Nicolai por seu esforço em me dar a oportunidade de fazer parte de seu laboratório, aprender o significado de colaboração internacional e os aspectos multiculturais da ciência. À Jeroen Lammertyn e seu conhecimento, ensinando-me novos conceitos. Ao meu amigo Thomas Vandendriessche, por sua amizade, motivação, incentivo e discussão. Sem você e sua paciência, parte desse trabalho não teria sido possível. À Annemie, Nicolas, Elfie, Marteen, Jeroen Pollet, Bert, Steven e todos os colegas do MeBioS. Obrigado por sua ajuda e suporte. Ao grupo de Polímeros Bernard Gross do Instituto de Física de São Carlos e todos os pesquisadores que colaboraram com esse trabalho, em especial Roberto Rita e Márcio. Em especial ao Jairzão pelas longas horas de discussão, ajuda, colaboração e incentivo. Aos professores do GEM, Fernando Fonseca, Ely Dirani e Roberto Onmori pelos conselhos, apoio, considerações e profunda amizade. Aos amigos do GEM, Guilherme, Leonardo, Gerson, Emerson, Helena, Nadja, Camila, Roberto Cavalari e tantos outros colegas que ao longo desse trabalho por algum momento contribuíram. Ao Leonardo Gonçalves pela ajuda valiosa com a análise das cachaças. À minha família, Christiano, Bernice, Christian, Paola, Christian Junior, Celso e Susan por me apoiarem esses anos, incentivarem, motivarem e me darem condições de realizar esse trabalho. Aos meus familiares distantes que também torcem por mim. À Michele Rodrigues por me acompanhar nesse processo, ser solidária, incentivadora, amiga e companheira. À todos os meus amigos em especial João, Felipe, Mexicano (Luis Fernando), Torrão (Fernando), Andrea, Carolzinha (Ana Carolina), Carolzona (Carolina), Maíra e Dani pelos momentos de descontração e incentivo.À FAPESP, Pró-reitoria de Pós Graduação, CAPES e CNPQ por financiamento através de projetos, bolsas e auxílio-viagem. RESUMOO estudo de sistemas voltados para a detecção e discriminação de compostos e substâncias gasosas tem se destacado nas áreas da nanociência e da nanotecnologia devido ao grande interesse no controle de odores e aromas presentes em alimentos, cosméticos e no meio ambiente. Dentre os diversos tipos de sensores matriciais de gases, conhecidos como narizes eletrônicos, os feitos à base de polímeros vêm se destacando devido ao baixo custo, fácil processabilidade, operação em temperatura ambiente e boa resposta sensorial. O presente trabalho mostra a confecção e análise de sensores poliméricos e um nariz eletrônico de pequenas dimensões, portátil e de baixo custo baseado em polímeros condutivos. Como materiais ativos dos sensores foram estudados materiais pertencentes à classe das polianilinas, politiofenos, polipirrol e ftalocianina de níquel, depositados por duas técnicas diferentes: spin coating e automontagem. As análises da espessura, reprodutib...
Artificial neural networks (ANN) were used to simulate the absorption spectra of PANI/PVS films deposited by the layer-bylayer (LBL) technique with different number of bilayers and doping levels. The PAni/PVS films are used to enhance electrical and optical performance of polymeric electroluminescent devices. In this work one hidden-layer Multilayer Perceptron (MLP) architecture was used. It is shown a comparison between experimental and simulated UV-Vis absorption spectra. This approach is proposed for the determination of thin-film design so as not to overlap the absorption spectra of Pani/PVS films with the device active layer emission spectra in order to enhance the device performance.IntroductionIt is known that thin-films of polyaniline (PAni), when used as hole transport layer (HTL), enhance electrical and optical characteristics of polymeric electroluminescent devices (1). In spite of this important benefit, thin-films of polyaniline/poly(vinyl sodium sulfate) (PVS) made by layer-by-layer (LBL) technique exhibits an absorption in the UV-Vis region. A compromise between electrical enhancement and light blocking/distortion is needed to assure an optimized electroluminescent device. PAni doping level (e.g. commonly by HCl) enhance the electrical transport properties by decreasing the interface resistance (2). It also broadens the polaronic band towards the spectrum to the infrared red region. For light emitting polymers (LEP) as MEH-PPV (emission from 550 to 680 nm) (3) when PAni is dedoped, the maximum absorbance peak lies down in 650nm compromising the LEP emission and the general device performance. Another important feature that interferes in the UV-Vis absorption spectrum is the thin-film thickness which gives different absorption amounts. Control of thickness, or in our case, the number of bilayers is crucial to not interfere substantially in the device emission behavior. Artificial Neural Networks (ANNs) are being used for several years in the simulation of non-linear problems (4). In our case of study, it was used a supervised network architecture type where it learns by examples. The main parameters in a multi-layer perceptron architecture (MLP) are the number of hidden layers, the number of neurons in the layers and the activation functions (5). As it was mentioned before, using an experimental data set it is possible to train the ANN to learn the process behavior. A data set is a set formed by inputs and output(s). For the ANN error analysis and generalization study it is common to separate the data set in two where the first is named training set and the second one test set. While the ANN is trained by the training set the test set is used to analyze the error over "unknown" conditions (not used in training) or in another words it is used to study generalization (5). When ANNs are being studied the mean squared error (MSE) is the main ANN analyzed characteristic because it shows how good are the trained architecture. Every training repetition is called an "epoch" and although it is a step countin...
This work deals with the electrical and optical response of poly (o-methoxyaniline) (POMA) thin films exposed to nitrogen and nitrogen with methanol. A low cost apparatus was developed for the optical assessment of the presence of methanol in an ambient. It is shown that thick POMA films exhibits a wide optical absorption variation when in presence of methanol. It was observed that the optical absorption characteristics return to the initial condition when methanol exposition ceases. Electrical response of a photoresistor to methanol showed larger relative variations but also presented large noise interference. A residual drift in the resistance is presented after every cycle and it need to be better evaluated.
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