Submitted by PPG Engenharia e Tecnologia de Materiais (engenharia.pg.materiais@pucrs.br) on 2018-08-23T14:01:45Z No. of bitstreams: 1 Sandro Fernandes Firmino_TESE.pdf: 4757608 bytes, checksum: 52ddad6a85c21dfa1d36627079848e04 (MD5) / Approved for entry into archive by Sheila Dias (sheila.dias@pucrs.br) on 2018-08-27T11:21:40Z (GMT) No. of bitstreams: 1 Sandro Fernandes Firmino_TESE.pdf: 4757608 bytes, checksum: 52ddad6a85c21dfa1d36627079848e04 (MD5) / Made available in DSpace on 2018-08-27T11:37:10Z (GMT). No. of bitstreams: 1 Sandro Fernandes Firmino_TESE.pdf: 4757608 bytes, checksum: 52ddad6a85c21dfa1d36627079848e04 (MD5) Previous issue date: 2018-08-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / This work proposes the development of a low cost protocol for the production of TCNTs based on silver nanowires (AgNWs) on rigid substrates, and the improvement of the deposition technique to obtain a higher layer homogeneous, aiming at the optimization of its optical and electrical properties. For this, silver nanowires with length and diameter control were produced, aiming to evaluate the influence of these parameters on the optical and electrical properties of TCTFs. The effects of thermal annealing on the morphology of AgNWs networks and on the electrical and optical properties of TCTFs were also investigated. Studies were carried out to improve the deposition technique to obtain more homogeneous films and, as a result of this study, a new deposition technique (VMCV - Vertical Controlled Mechanical Vibration) was developed with INPI (National Institute of Intellectual Property). Silver nanowires were synthesized through the polyol process, which uses a polymer (N-vinylpyrrolidone) (PVP) as the coating agent. The prepared solutions of AgNWs were deposited on rigid substrates (glass / silicon) for analysis of topological and chemical surfaces, resulting in a random network of nanowires. The networks of AgNWs were characterized by MEV-FEG, UV-Vis, XPS and DSC-TGA techniques. The effect of thermal annealing on the AgNWs networks was investigated by means of in situ measurements of the evolution of the electrical resistances, through the technique of two tips, on a hot plate with temperature control system. Our best results exhibit an optical transparency (~ 83% at 550 nm) equivalent to commercial metal oxide thin films (indium oxide-oxide, ITO or fluoride oxide and tin oxide, FTO) and sheet resistance of ~ 23 ? / ?. / Este trabalho tem como proposta o desenvolvimento de um protocolo de baixo custo para produ??o de TCTFs (Filmes Finos Condutores Transparentes) ? base de nanofios de prata (AgNWs) sobre substratos r?gidos, e o aperfei?oamento da t?cnica de deposi??o para a obten??o de uma camada homog?nea, visando ? otimiza??o de suas propriedades ?pticas e el?tricas. Para isto, foram produzidos nanofios de prata com controle de comprimento e di?metro, visando avaliar a influ?ncia destes par?metros sobre as propriedades ?pticas e el?tricas dos TCTFs. Tamb?m foram investigados os efeitos do recozimento t?rmico na morfologia das redes de AgNWs e sobre as propriedades el?tricas e ?pticas dos TCTFs. Foram realizados estudos para o aperfei?oamento da t?cnica de deposi??o para a obten??o de filmes homog?neos e, como resultado deste estudo, desenvolveu-se uma nova t?cnica de deposi??o (VMCV- Vibra??o Mec?nica Controlada Vertical) registrada junto ao INPI (Instituto Nacional de Propriedade Intelectual). Os nanofios de prata foram sintetizados atrav?s do processo poliol, que utiliza um pol?mero (N-vinilpirrolidona) (PVP) como o agente de cobertura. As solu??es preparadas de AgNWs foram depositadas sobre substratos r?gidos (vidro/sil?cio) para an?lises de superf?cies topol?gicas e qu?micas, resultando em uma rede aleat?ria de nanofios. As redes de AgNWs foram caracterizadas pelas t?cnicas MEV-FEG, UV-Vis, XPS e DSC-TGA. O efeito do recozimento t?rmico sobre as redes de AgNWs foi investigado por meio de medi??es in situ da evolu??o das resist?ncias el?tricas, atrav?s da t?cnica de duas pontas, sobre uma chapa quente com sistema de controle de temperatura. Nossos melhores resultados exibem uma transpar?ncia ?ptica (~ 83% a 550 nm) equivalente a das pel?culas finas de ?xido de metal comercial (?xido de ?ndio-?xido, ITO ou ?xido de fl?or e ?xido de estanho, FTO) e resist?ncia de folha de ~ 23 ?/?.

Polymer/inorganic nanoparticle hybrid thin films, primarily composed of functional inorganic nanoparticles, are of great interest to researchers because of their interesting electronic, photonic, and optical properties. In the past two decades, layer-by-layer (LbL) assembly has become one of the most powerful techniques to fabricate such hybrid thin films. This method offers an easy, inexpensive, versatile, and robust fabrication technique for multilayer formation, with precisely controllable nanostructure and tunable properties. In this thesis, various ways to control the structure of hybrid thin films, primarily composed of polyelectrolytes and indium tin oxide (ITO), are the main topics of study. ITO is one of the most widely used conductive transparent oxides (TCOs) for applications such as flat panel displays, photovoltaic cells, and functional windows. In this work, polyethyleneimine (PEI) was used to stabilize the ITO suspensions and improve the film buildup rate during the LbL assembly of poly(sodium 4-styrenesulfonate) (PSS) and ITO. The growth rate was doubled due to the stronger interaction forces between the PSS and PEI-modified ITO layer. The assembly of hybrid films was often initiated by a polyelectrolyte precursor layer, and the characteristics of the precursor layer were found to significantly affect the assembly of the hybrid thin films. The LbL assembly of ITO nanoparticles was realized on several substrates, including cellulose fibers, write-on transparencies, silicon wafers, quartz crystals, and glasses. By coating the cellulose fibers with ITO nanoparticles, a new type of conductive paper was manufactured. By LbL assembly of ITO on write-on transparencies, transparent conductive thin films with conductivity of 10⁻⁴ S/cm and transparency of over 80 % in the visible range were also prepared. As a result of this work on the mechanisms and applications of LbL grown films, the understanding of the LbL assembly of polyelectrolytes and inorganic nanoparticles was significantly extended. In addition to working with ITO nanoparticles, this thesis also demonstrated the ability to grow bicomponent [PEI/SiO₂]n thin films. It was further demonstrated that under the right pH conditions, these films can be grown exponentially (e-LbL), resulting in much thicker films, consisting of mostly the inorganic nanoparticles, in much fewer assembly steps than traditional linearly grown films (l-LbL). These results open the door to new research opportunities for achieving structured nanoparticle thin films, whose functionality depends primarily on the properties of the nanoparticles.