Orientador: Steven Frederick Durrant / Banca: Johnny Vilcarromero Lopez / Banca: Nelson Marques da Silva / O Programa de Pós-Graduação em Ciência e Tecnologia de Materiais, PosMat, tem carater institucional e integra as atividades de pesquisa em materiais de diversos campi da Unesp / Resumo: Nestre trabalho, Polietrafluroetileno (PTFE) foi tratado por três técnicas: (1) exposição a plasma com gases não polimerizáveis (Ar, He, H2, O2, e N2), num reator a plasma com arranjo capacitivo dos eletrodos, excitado por radiofrequencia (rf);(2) ablação em eletrodo de cobre excitado por rf, com subsequente implantação iônica e deposição por imersão em plasma (IIDIP); e (3) rf-magnetron sputterring associado com IIDIP. Investigaram-se os efeitos dos tratamento nas propriedades superficiais e elétricas do substrato. O objetivo foi reduzir a capacidade do PTFE à acumulação de cargas elétricas. As alterações de molhabilidade e energia de superfície foram obtidas por medida do ângulo de contato. A espessura e a rugosidade foram medidas por perfilometria e microscopia de força atômica (AFM). A estrutura e composição química da superfície foram analisadas por espectroscopia no infravermelho por tranformada de Fourier (FTIR) e espectroscopia de fotoelétrons de raios-X (XPS). A resistividade elétrica superficial foi medida através de eletrômetro pelo método dos dois pontos. As caracterizações demonstraram que a técnica (1) foi capaz de alterar as características superficiais do substrato em muitos aspectos, mas não foi suficiente para reduzir sua resistividade elétrica superficial. Para a técnica (2) os resultados de XPS revelaram a presença de cobre na superfície do substrato, mas em quantidade insuficiente para causar os efeitos de percolação desejados. Na técnica (3) partículas de cobre foram incorporadas nos substratos, formando filmes com espessura de até 4000 A e reduzindo a resistividade elétrica superficial em até oito ordens de grandeza. PTFE tratados por rf-magnetron sputtering com um cátodo de cobre perdeu sua habilidade de reter cargas eletrostáticas / Abstract: In this work, polytetrafluroethylene (PTFE) was treated using three techniques: (1) plasma treatment with non-polymerizable gases (Ar, He, H2, O2 and N2), in a plasma reactor fitted with capacitive electrodes and excited by rf power; (2) ablation of a copper electrode excited by rf, with subsequent plasma immersion ion implantation and deposition (PIIID); (3) rf-magnetron sputerring associated with PIIID. The effects of treatments on the electrical and surface properties of the substrates were investigated. The objective was to reduce the capacity of PTFE to accumulate surface electrical charges. Changes in wettability and surface energy were obtained by measuring the contact angle. Thicknesses and roughnesses were examined using profilometry and atomic force microscopy (AFM). The chemical structure of the surface was analyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Surface electrical resistivity was measured with an electrometer by applying the two-point method. The characterizations revealed that method (1) was able to alter the characteristics of the substrates in many respects, but not to significantly modify their surface electrical resistivity. After treatment by method (2), XPS results revealed the presence of copper on the substrate surface, but in insufficient quantify to cause the desired percolation effect. In method (3) copper particles were incorporated into the substrates to form films with thicknes of up to 4,000 A and the electrical surface resistivity was reduced by eight orders of magnitude. PTFE treated by rf-magnetron sputerring with a copper cathode los its ability to retain electrostatic charges / Mestre

Capillary electrophoresis chip has gradually ripe along with the development of MEMS technology. However, such these electrophoresis chips was design closed-channel form whose process including the micro-channel forming and chip bonding and so on, so the cost is higher. In addition, if these chips use repeated will cause some pollution problems such as obstruction or difficult to clean in the closed-channel. Therefore, to fabricate a non-closed microfluidic chip system will resolve the issues above listed. In this study has successful developed a convenient and low-cost thread microfluidic system, the thin polyester thread is instead of the traditional closed separation channel. And to avoid the cross contaminations that the separation channel can free replace a new electrophoresis separation channel by the roller equipment. Thread microfluidic systems can take advantage of capillary action to move, as a disposable chromatography flow channel, and the electric field is applied to this system for electrophoresis separation and electrochemical detection in the backend. This research develop an novel process technology, the hot embossing technology shape from concave embossing and metal coating procedure in PMMA, the salient pillow-electrode structure has be produced in PMMA board, the salient electrode structure set up the polyester fiber thread, the polyester fiber thread is as the electrophoresis separation channel, and electrochemical detect samples in back-end. In this study take plasma treatment to improve wettability and surface roughness of the polyester fiber thread, in order to improve the operational effectiveness of the thread microfluidic systems. The cyclic voltammetry measure potassium ferricyanide samples and the results showed that the performance of thread microfluidic system significantly increase after the plasma treatment, the measuring current value is 10 times greater than without the plasma treatment, and the estimated detection limit of potassium ferricyanide is around 6.25 £gM in the plasma treatment one. In addition, the thread microfluidic devices with plasma treatment has successful separation and detection the mixing samples of 0.3 mM chlorine, bromine and iodine ions, and the signal of the S/N ratio is 6 times higher than the without plasma treatment one, and the number of theoretical plates of electrophoresis separation also enhance to 28% in the plasma treatment one. In addition, in order to further enhance the detection sensitivity of the thread microfluidic systems, the study design and fabricate the concave-shaped three-dimensional electrode structure, and to achieve greater contact area between thread and the electrode. Thread microfluidic system with plasma treatment detect in concave-shaped three-dimensional electrode and flat electrode respectively, the results showed that concave-shaped electrodes in the potassium ferricyanide detection limit that measured current value is 10 times greater than flat electrode, and a mixture of dopamine and catechol sample are electrophoresis separated that concave-shaped 3D electrode whose measured S/N ratio is 5 times higher than flat electrode, and the number of theoretical plates is 1.5 times higher than the flat electrode. This study develops a novel thread microfluidic system that will provide a simple process and low-cost, and can solve the shortcomings of conventional closed-channel electrophoresis chips. In future, in this study develop the thread microfluidic system architecture will have contribute for fast electrophoresis separation and detection.

In this study,The bottom electrode(TiN),middle insulator(Hf:SiOx),and top electrode(Pt) were deposited respectively by sputtering technique for fabricating the RRAM with MIM structure.The mole fraction of hafnium were about 5%.Instead of non-doped SiO2 base device has no switching characteristic,the Hf-doped SiO2 RRAM could be operator over 100 times and resistive state was kept stable over 104 second. In this researches,the double layer structure(Pt/Hf:SiO2/Hf:SiO2(doped N2 and NH3)).The Resistance switching characteristics of double layer structure device has particular I-V characteristics due to the doping of N.The doping of NH3 cause hydrogen plasma treatment on double layer device also bring about particular I-V characteristics. The physical mechanism we had proposed were proof by the Current-Voltage fitting and the material analysis.By control stop-voltage,the double layer structure device can operation by multi-bit. The detail physical mechanism is studied by the stable RRAM device(Ti/HfO2/TiN).In this study,the model of reset process we had proposed were proof by the special measurement methods(Constant-voltage sampling) and the principle of chemical reaction mechanism.

Polymeric waveguide-on-flex has the potential to replace complex and costly light-turning devices in optoelectronic applications. As light signals are propagated and confined through the definition of core-cladding interface, the light guiding structure is required to adhere well and ensure long term interfacial stability. This thesis addresses the gap that has emerged in the fundamental material issues such as the polymeric optical waveguide materials deposited on the flexible substrates. In addition, this thesis investigates the feasibility of a new approach using electrostatic-induced lithography in micro-patterning of polymer, in optical waveguide fabrication. Plasma treatment is applied to enhance interfacial adhesion between flex substrates and optical cladding layers. The modified flex surfaces of polyimide KaptonHNTM and liquid crystal polymer VecstarTM materials are characterised. In addition, sonochemical surface treatment is evaluated on these flexible substrates. ToF-SIMS depth profiling has confirmed the interface reaction mechanisms where it has shown that plasma treatment increases the interfacial interpenetration. The larger interfacial width increases the possible entanglement mechanism between the polymer chains. These results, together with the double cantilever beam testing, indicate the strengthening of the polymeric interface upon plasma treatment, which is essential for long term optical and mechanical stability of waveguide-on-flex applications. A new method of micro-pattering of polymer material has been adopted for fabricating multimode waveguide-on-flex. The method, using an electrostatic-induced lithography, is developed to produce 50 μm x 50 μm arrays of polysiloxane LightlinkTM waveguide on flex. This thesis looks at various process recipes of the technique and reports the pattern formation of polymeric optical core. By adjusting the spin-coated liquid core thickness, pre-bake condition, UV exposure and applied voltage, the aspect ratio and profile of the optical core microstructure can be varied. As the electrostatic pressure overcoming the surface tension of spin-coated waveguide material induces the optical core formation, the core structure is smooth, making it ideal for low scattering loss waveguide. The propagation loss of fabricated waveguide is measured at 1.97 dB/cm at 850 nm wavelength. The result shows that the use of electrostatic-induced lithography in optical polymer is a promising approach for low cost and low temperature (<150 °C) processing at back end optical-electrical integrated circuitry assembly.

The research presented in this dissertation explores the possibility of using colloidal indium tin oxide (ITO) nanoparticle solutions to direct write transparent conducting coatings (TCCs), as an alternative route for TCC fabrication. ITO nanoparticles with narrow size distribution of 5-7 nm were synthesized using a non-aqueous synthesis technique, and fabricated into films using spin coating on substrates made from glass and fused quartz. The as-coated films were very transparent (>95% transmittance), but highly resistive, with sheet resistances around 10¹³ Ω/sq . Pre-annealing plasma treatments were investigated in order to improve the electrical properties while avoiding high temperature treatments. Composite RIE treatment recipes consisting of alternating RIE treatments in O₂ plasma and in Ar plasma were able to reduce the sheet resistance of as spin coated ITO films by 4-5 orders of magnitude, from about 10¹³ Ω/sq in as-coated films to about 3 x 10⁸ Ω/sq without any annealing. Plasma treatment, in combination with annealing treatments were able to decrease the sheet resistance by 8-9 orders of magnitude down to almost 10 kΩ/sq , equivalent to bulk resistivity of ~0.67 Ω.cm. Investigation into effectiveness of various RIE parameters in removing residual organics and in reducing the sheet resistance of colloidal ITO films suggested that while reactive ion annealing (RIE) pressure is an important parameter; parameters like plasma power, number of alternating O₂-Ar RIE cycles were also effective in reducing the residual organic content. Impedance spectroscopy analysis of the colloidal ITO films indicated the dominance of the various interfaces, such as grain boundaries, insulating secondary phases, charge traps, and others in determining the observed electrical properties.

Submitted by Milena Kowalczuk Manosso Amorim (milenamanosso@gmail.com) on 2018-09-10T23:00:08Z No. of bitstreams: 1 versão repositorio 10-09.pdf: 2679208 bytes, checksum: 1f7039ea349763e1a7142ce20ee9a3de (MD5) / Approved for entry into archive by Lucilene Cordeiro da Silva Messias null (lubiblio@bauru.unesp.br) on 2018-09-11T16:47:09Z (GMT) No. of bitstreams: 1 amorim_mkm_me_bauru.pdf: 2679208 bytes, checksum: 1f7039ea349763e1a7142ce20ee9a3de (MD5) / Made available in DSpace on 2018-09-11T16:47:09Z (GMT). No. of bitstreams: 1 amorim_mkm_me_bauru.pdf: 2679208 bytes, checksum: 1f7039ea349763e1a7142ce20ee9a3de (MD5) Previous issue date: 2018-07-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho investiga os efeitos de tratamento a plasma frio em polímeros convencionais, polipropileno e poliestireno, e em filme amorfo do tipo a-C-H, produzido através de Deposição Química de Vapor Assistida por Plasma (PECVD). Após etapas preliminares de escolha de gás e tempo a serem utilizados, as amostras foram tratadas em plasma de hexafluoreto de enxofre (SF6) em cinco diferentes potências e cinco diferentes pressões, totalizando 25 condições para cada substrato. As superfícies foram caracterizadas por goniometria, perfilometria, Espectroscopia de Infravermelho com Transformada de Fourier (FTIR), Microscopia Eletrônica de Varredura (MEV), Espectroscopia de Raios-X por Energia Dispersiva (EDS) e Espectroscopia de Fotoelétrons Excitados por Raios-X (XPS). Assim, foram examinados ângulo de contato, rugosidade, estrutura química, morfologia, composição química e composição química da superfície, respectivamente. O tratamento com SF6 aumenta a característica hidrofóbica dos três materiais, possivelmente devido à incorporação de flúor nas superfícies. A combinação de potência e pressão que promoveu aumento mais significativo em ϴ variou para cada material: 80 W e 80 mTorr para o filme amorfo, aumentando de 60,6° para 111,1° nestas condições, 20 W e 40 mTorr para o polipropileno, aumentando de 81,8° para 119° e 100 W e 60 mTorr para o poliestireno, aumentando de 74° para 95°. As análises por XPS indicaram a presença de flúor após os tratamentos com plasmas de SF6, mostrando um aumento da razão F/C de 0 para todas as amostras não tratadas para 0,03 para o filme amorfo tratado, 0,14 para o polipropileno tratado, e 0,60 para o poliestireno tratado. / The present work investigates the effects of plasma treatment on conventional polymers, polypropylene and polystyrene, and on amorphous hydrogenated carbon, a-C-H, obtained by Plasma Enhanced Chemical Vapour Deposition, (PECVD). After preliminary studies to establish the plasma gas and treatment times, samples were treated in sulphur hexafluoride (SF6) plasmas at five different powers and five different pressures. Surfaces were characterized by goniometry, profilometry, Fourier Transform Infrared Spectrometry, Scanning Electron Microscopy (SEM), EnergyDispersive X-ray Spectroscopy (EDS) and X-Ray Photoelectron Spectroscopy (XPS). Thus, contact angle, roughness, chemical structure, morphology, chemical composition and surface chemical composition were examined. Results show that SF6 treatments increase the hydrophobicity of the three substrates, possibly due to the surface incorporation of fluorine. The power and pressure combinations that caused the greatest improvements in ϴ were as follows: 80 W and 80 mTorr for the amorphous film, resulting in an increase from 60.6° to 111.11°; 20 W and 40 mTorr for polypropylene, resulting in an increase from 81,8° to 119°; 100 W and 60 mTorr for polystyrene, resulting in an increase from 74° to 95°. The presence of fluorine following the SF6 plasma treatments was confirmed by the XPS analyses, which showed that F/C increased from 0 for all the untreated samples to 0,03 on treated amorphous films, to 0,14 on treated polypropylene, and to 0,60 on treated polystyrene.

Neste trabalho se realiza a síntese e caracterização de nanofios de óxido de zinco. Adicionalmente se apresenta o processo de montagem de um dispositivo para medidas elétricas deste material. Estuda-se complementarmente o efeito do tratamento de plasma sobre as propriedades de fotoluminescência do material. Nanofios foram sintetizados pelo mecanismo vapor-líquido-sólido (VLS), utilizando ouro como catalizador e safira c-plane como substrato. As amostras foram caracterizadas utilizando microscopia eletrônica de varredura, fotoluminescência a temperatura ambiente, difração de raios X, e microscopia eletrônica de transmissão. Os nanofios obtidos têm seção transversal com formato quase hexagonal, e larguras de aproximadamente 46 nm. O comprimento deles varia de 3 a 10 μm. Os resultados de difração de raios x e microscopia eletrônica de transmissão mostram que eles são monocristalinos com rede cristalina tipo wurtzita, e com direção de crescimento no eixo c. Foram estudados os efeitos da potência de plasma de oxigênio (O2) na fotoluminescência dos nanofios a temperatura ambiente. A diferença na fotoluminescência após diferentes tratamentos de plasma de O2 mostra que a razão entre a emissão da região do band gap e da banda do visível pode ser modificada pelo tratamento. Este efeito corrobora com a hipótese de que a banda verde de luminescência está relacionada às vacâncias de zinco. A variação percentual da razão entre as duas regiões apresenta uma dependência linear com a potência do plasma. / In this work, we performed the synthesis and characterization of zinc oxide nanowires. We also report an assembly process to measure the electrical properties of this material. We study the plasma treatment effect on the photoluminescence spectra of the nanowires. Nanowires were synthesized via vapor-liquid-solid mechanism, using gold as catalyst and c-plane sapphire as substrate. The samples were characterized using scanning electron microscopy, room temperature photoluminescence, x-rays diffraction and transmission electron microscopy. Our nanowires show a quasi-hexagonal cross section, with diameters of approximately 46 nm. Their lengths ranged from 3 to 10 μm. Our results show monocrystalline wurtzite crystal nanowires with c growth direction. We also study the plasma power effect of oxygen (O2) plasma treatment on the room temperature photoluminescence spectra of the nanowires. Our results show that the deep level emission to near band emission ratio decreases with the plasma treatment. This effect supports the hypothesis that claims the green band luminescence is related to the oxygen vacancies. Furthermore, the relative ratio change depends linearly on the plasma power.

Made available in DSpace on 2014-06-11T19:32:50Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-09Bitstream added on 2014-06-13T19:22:32Z : No. of bitstreams: 1 marins_nms_dr_guara.pdf: 1433472 bytes, checksum: cedcb76a6d8c4184098e03ae116ba45c (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Filmes finos de carbono amorfo hidrogenado (a-C:H) e fluorados (a-C:H:F) foram depositados a partir de plasmas de misturas de acetileno/argônio e acetileno/argônio/hexafluoreto de enxofre. Para a primeira mistura de gases, o plasma foi mantido por 5 e 10 minutos a uma pressão de 9,5 Pa (30% C2H2 e 70% Ar) enquanto para a segunda ele foi mantido por 5 minutos utilizando-se 30% C2H2, 65% Ar e 5% SF6 a uma pressão total de 9,5 Pa. A potência do sinal de excitação foi variada de 5 a 125 W e o efeito deste parâmetro nas propriedades do filme foi investigado. De modo a fluorar os filmes obtidos a partir da mistura acetileno/argônio estes foram submetidos, imediatamente após a deposição e sem exposição ao ar atmosférico, a tratamentos em plasmas de SF6. Tais procedimentos foram conduzidos durante 5 minutos utilizando-se uma fonte de rádiofrequência (13,56 MHz, 70 W) a uma pressão total de 13,3 Pa. Foram utilizadas as técnicas de espectroscopia Raman e espectroscopia de fotoelétrons – XPS para investigar as respectivas microestruturas e composições químicas das amostras. A dureza e o coeficiente de atrito dos filmes foram determinados pelas técnicas de nanoindentação e tribometria, respectivamente. A receptividade das amostras à água foi analisada através de dados de ângulo de contato e a rugosidade foi determinada por interferometria ótica. Os filmes de a-C:H obtidos a partir de plasmas de C2H2 e Ar em potências mais baixas (5 e 25 W) apresentaram estruturas e composições de natureza polimérica, enquanto os preparados em potências intermediárias (50 e 75 W) apresentaram maiores proporções de ligações de carbono tetraédricos e baixo teor de hidrogênio, indicando uma estrutura do tipo DLC (Diamond-Like Carbon). Os filmes depositados com as potências mais elevadas (100 e 125 W) apresentaram estrutura do tipo grafitica... / Hydrogenated amorphous carbon (a-C:H) and fluorinated (a-C:H:F) thin films were deposited from acetylene/argon and acetylene/argon/sulfur hexafluoride mixtures. For the first gas mixture, the plasma was kept for 5 or 10 minutes using 9.5 Pa of pressure (30% C2H2 e 70% Ar) while for the second it was kept for 5 minutes using 30% C2H2, 65% Ar e 5% SF6 at a total pressure of 9.5 Pa. The power of the excitation signal was changed from 5 to 125 W and the effect of such parameter on the properties of the films was investigated. To fluorinate the a-C:H films they were submitted, immediately after deposition and without exposure to atmosphere, to SF6 plasma treatments. Such procedures were conducted for 5 minutes in radiofrequency (13.56 MHz, 70 W) plasmas of 13.3 Pa of pressure. Raman and X-Ray photoelectron spectroscopes were employed to investigate, respectively, the microstructure and chemical composition of the films. Film hardness and friction coefficient were determined from nanoindentation and tribometry techniques, respectively. The receptivity of the samples towards water was evaluated through contact angle data and roughness was measured by optical interferometry. The a-C:H films obtained from the C2H2 and Ar plasma mixtures in lower power (5 e 25 W) presented polymer-like structures and compositions while those prepared using intermediary power levels ( 50 e 75 W) presented higher proportions of tetrahedral carbon bonds and low proportions of hydrogen, suggesting a Diamond like Carbon (DLC) structure. Films deposited using the higher power (100 e 125 W) plasmas presented a graphitic structure. As the material prepared with lower power signals were submitted to the SF6 post deposition treatment, surface chemical composition was changed but the polymeric nature of the films was kept. The graphitic nature of the films synthesized in the higher power regime was intensified after... (Complete abstract click electronic access below)

Submitted by GILSON PIQUERAS GARCIA null (gilson.piqueras@gmail.com) on 2018-03-13T17:35:56Z No. of bitstreams: 1 Garcia, Gilson Piqueras. Efeito do tratamento de polímeros em plasmas de nitrogênio 2018. Tese (Doutorado).pdf: 3148171 bytes, checksum: 4ca44c01e1ec375c08f9b89261de68f3 (MD5) / Approved for entry into archive by Lucimara Kurokawa Shinoda null (lucimaraks@sorocaba.unesp.br) on 2018-03-14T17:38:12Z (GMT) No. of bitstreams: 1 garcia_gp_dr_soro.pdf: 3148171 bytes, checksum: 4ca44c01e1ec375c08f9b89261de68f3 (MD5) / Made available in DSpace on 2018-03-14T17:38:12Z (GMT). No. of bitstreams: 1 garcia_gp_dr_soro.pdf: 3148171 bytes, checksum: 4ca44c01e1ec375c08f9b89261de68f3 (MD5) Previous issue date: 2018-02-20 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O politetrafluoretileno (PTFE) e a poliamida 6 (PA 6) são polímeros que têm excelentes qualidades mecânicas, elétricas e químicas. Por isto, são utilizados em diversos componentes de equipamentos mecânicos e elétricos entre várias outras aplicações. Entretanto o PTFE possui um ângulo de contato com a água (WCA) de cerca de 120º e a PA 6 um WCA de cerca de 60º. Isto, especialmente no caso do PTFE, diminui a sua adesividade com outros materiais. Para resolver este problema várias técnicas têm sido sugeridas, como, por exemplo, tratamentos químicos e tratamento a plasma. Entre elas o tratamento a plasma, que tem a vantagem de produzir modificações apenas na superfície, não alterando o interior do material. O objetivo deste trabalho é estudar como o WCA varia em função dos parâmetros do tratamento a plasma de nitrogênio, a pressão do gás (p), a potência (P) e o tempo de tratamento (t). O nitrogênio foi escolhido por ser um gás cujo plasma, segundo a literatura, causa reduções significativas no ângulo de contato da superfície de polímeros. Várias séries de tratamento foram conduzidas, tanto para o PTFE quanto para a PA 6. Foram obtidas reduções significativas no WCA, ocorrendo o resultado notável de WCA = 0º para p = 2,6 Pa, P = 300 W e t = 30 min, tanto para o PTFE quanto para a PA 6. Em função dos resultados, dentro do intervalo de parâmetros utilizado, concluiu-se que, de uma forma geral, o WCA diminui com a potência e com o tempo de tratamento, e que o WCA tem um comportamento notável em função da pressão do gás, diminuindo inicialmente até atingir o valor mínimo (ótimo) de 0º para p = 2,6 Pa, e então passa a crescer a partir deste ponto. A redução do WCA das amostras tratadas foi consequência do aumento da energia de superfície, motivado pela incorporação de funções nitrogenadas e oxigenadas nas suas superfícies. A Espectroscopia de fotoelétrons excitados por raios X (XPS) foi usada para caracterizar a composição e estrutura da superfície do PTFE e da PA 6. A rugosidade e o ângulo de contato dos polímeros foram medidos por perfilometria e goniometria, respectivamente. A análise XPS mostrou, para o PTFE, que houve incorporação de oxigênio e nitrogênio, para a PA 6, o aumento da concentração de oxigênio, e para ambos, a presença de grupos químicos polares em sua superfície. As medições do WCA em função do tempo decorrido após o de tratamento, mostraram que, para o PTFE e para a PA 6, o WCA volta a crescer, estabilizando em torno de 90 dias, quando, para o PTFE atinge cerca de 80% do WCA da amostra sem tratamento. A PA 6 apresentou um resultado notável, com o WCA estabilizando com um valor de cerca do dobro do valor do WCA da amostra sem tratamento, o que transforma a sua superfície de hidrofílica para hidrofóbica, possibilitando novas possibilidades de usos em engenharia. / Polytetrafluoroethylene (PTFE) and polyamide 6 (PA 6) are polymers that have excellent mechanical, electrical and chemical properties. Therefore, they are used in diverse mechanical and electrical equipment components among many other applications. However, PTFE has a water contact angle (WCA) about of 120º and PA 6 has a WCA about of 60º. This, especially for PTFE, decreases their adhesiveness with other materials. To solve this problem, many techniques have been proposed, such as chemical and plasma treatments. Among them the plasma treatment has the advantage of producing modifications on the surface only, altering the bulk. The objective of this work is to study how the WCA varies as a function of the nitrogen plasma treatment parameters, the gas pressure (p), the applied power (P) and the treatment time (t). Nitrogen plasmas were used in this study since, according the literature, such plasmas significantly reduce the surface contact angle of polymers. Several series of treatment were conducted, for PTFE as for PA 6. Significant reductions in WCA were obtained, including a WCA of 0º notable for p = 2.6 Pa, P = 300 W and t = 30 min, for PTFE as for PA 6. Thus, from the results, within the range of the parameters studied, it was concluded that, in general, the WCA diminishes as the power and as the treatment time increases, and that the WCA has a notable behavior as a function of the gas pressure, initially decreasing to reach a minimum (optimum) value of 0 º for p = 2.6 Pa, and then increasing after this point. The reduction in WCA of the treated samples was a consequence of the increase in surface energy, motivated by the incorporation of surface functionalities. X-ray photoelectron spectroscopy (XPS) was used to characterize the structure and composition of the PTFE and PA 6 surfaces. Roughness and surface contact angles of the polymers were measured using profilometry and goniometry, respectively. XPS analyses reveal, for PTFE, the incorporation of oxygen and nitrogen, for PA 6 the increase of oxygen concentration, and for both the presence of polar chemical groups on the treated surface. Measurement of the WCA as a function of the time after the treatment, showed that, for PTFE and PA 6, the WCA tends to increase, stabilizing after about 90 days, when, for PTFE, it reaches about of 80% of the value for virgin PTFE. PA 6 showed a notable result, the WCA stabilized at about double the value of the WCA of virgin PA6, indicating a switch from a hydrophilic to a hydrophobic surface, thus enabling new uses as an engineering polymer.

Resumo: Filmes finos de carbono amorfo hidrogenado (a-C:H) e fluorados (a-C:H:F) foram depositados a partir de plasmas de misturas de acetileno/argônio e acetileno/argônio/hexafluoreto de enxofre. Para a primeira mistura de gases, o plasma foi mantido por 5 e 10 minutos a uma pressão de 9,5 Pa (30% C2H2 e 70% Ar) enquanto para a segunda ele foi mantido por 5 minutos utilizando-se 30% C2H2, 65% Ar e 5% SF6 a uma pressão total de 9,5 Pa. A potência do sinal de excitação foi variada de 5 a 125 W e o efeito deste parâmetro nas propriedades do filme foi investigado. De modo a fluorar os filmes obtidos a partir da mistura acetileno/argônio estes foram submetidos, imediatamente após a deposição e sem exposição ao ar atmosférico, a tratamentos em plasmas de SF6. Tais procedimentos foram conduzidos durante 5 minutos utilizando-se uma fonte de rádiofrequência (13,56 MHz, 70 W) a uma pressão total de 13,3 Pa. Foram utilizadas as técnicas de espectroscopia Raman e espectroscopia de fotoelétrons - XPS para investigar as respectivas microestruturas e composições químicas das amostras. A dureza e o coeficiente de atrito dos filmes foram determinados pelas técnicas de nanoindentação e tribometria, respectivamente. A receptividade das amostras à água foi analisada através de dados de ângulo de contato e a rugosidade foi determinada por interferometria ótica. Os filmes de a-C:H obtidos a partir de plasmas de C2H2 e Ar em potências mais baixas (5 e 25 W) apresentaram estruturas e composições de natureza polimérica, enquanto os preparados em potências intermediárias (50 e 75 W) apresentaram maiores proporções de ligações de carbono tetraédricos e baixo teor de hidrogênio, indicando uma estrutura do tipo DLC (Diamond-Like Carbon). Os filmes depositados com as potências mais elevadas (100 e 125 W) apresentaram estrutura do tipo grafitica... (Resumo completo, clicar acesso eletrônico abaixo) / ABSTRACT: Hydrogenated amorphous carbon (a-C:H) and fluorinated (a-C:H:F) thin films were deposited from acetylene/argon and acetylene/argon/sulfur hexafluoride mixtures. For the first gas mixture, the plasma was kept for 5 or 10 minutes using 9.5 Pa of pressure (30% C2H2 e 70% Ar) while for the second it was kept for 5 minutes using 30% C2H2, 65% Ar e 5% SF6 at a total pressure of 9.5 Pa. The power of the excitation signal was changed from 5 to 125 W and the effect of such parameter on the properties of the films was investigated. To fluorinate the a-C:H films they were submitted, immediately after deposition and without exposure to atmosphere, to SF6 plasma treatments. Such procedures were conducted for 5 minutes in radiofrequency (13.56 MHz, 70 W) plasmas of 13.3 Pa of pressure. Raman and X-Ray photoelectron spectroscopes were employed to investigate, respectively, the microstructure and chemical composition of the films. Film hardness and friction coefficient were determined from nanoindentation and tribometry techniques, respectively. The receptivity of the samples towards water was evaluated through contact angle data and roughness was measured by optical interferometry. The a-C:H films obtained from the C2H2 and Ar plasma mixtures in lower power (5 e 25 W) presented polymer-like structures and compositions while those prepared using intermediary power levels ( 50 e 75 W) presented higher proportions of tetrahedral carbon bonds and low proportions of hydrogen, suggesting a Diamond like Carbon (DLC) structure. Films deposited using the higher power (100 e 125 W) plasmas presented a graphitic structure. As the material prepared with lower power signals were submitted to the SF6 post deposition treatment, surface chemical composition was changed but the polymeric nature of the films was kept. The graphitic nature of the films synthesized in the higher power regime was intensified after... (Complete abstract click electronic access below) / Orientadora: Elidiane Cipriano Rangel / Coorientador: Rogério Pinto Mota / Banca: Konstantin Georgiev Kostov / Banca: Mauríco Antonio Algatti / Banca: Jonny Vilcarromero Lopez / Banca: Pedro Augusto de Paula nascente / Doutor