Neste trabalho, filmes híbridos produzidos pela técnica da automontagem eletrostática camada-por-camada foram preparados usando-se Polioxometalatos do tipo Keggin, ácido fosfotúngstico (HPW) e o complexo monolacunar K(TPA)4[PW11O39Mn(OH2)] alternados via um polímero catiônico, poli(cloreto de alilamônio) (PAH). O filme que continha uma pré-camada de adsorção de PDMS, juntamente com 5 bicamadas de PAH e HPW apresentou um melhor comportamento eletroquímico em filmes formados sobre óxido de índio e estanho (ITO). Em função disso, este filme foi caracterizado através de Espectroscopias de Absorção na região do Ultra-Violeta Visível (UV-vis), de Absorção-Reflexão na Região do Infra-vermelho (FT-IRRAS) e de Ressonância de Plásmons de Superfície (SPR). Foi constatado por FT-IRRAS que parte da camada de PDMS está se difundindo para a superfície quando as bicamadas de PAH e HPW vão sendo preparadas. Imagens de Microscopia Eletrônica de Varredura com Emissão de Campo (MEV-EC) confirmam esta hipótese. Espectroscopia de SPR indicou que tanto a adsorção de PAH quanto a de HPW ocorrem em tempos curtos. Experimentos de Voltametria Cíclica com [Fe(CN)6]3-mostraram que este filme é poroso. Resultados de Espectroscopia de Fotoelétrons Excitados por Raios X (XPS) comprovaram que PDMS protege o substrato contra corrosão. Esse mesmo filme pôde ser utilizado numa aplicação de caráter ambiental. Ele foi capaz de detectar melamina e atrazina em concentrações 4.10-8 mol.L-1 e 1.10-6 mol.L-1 respectivamente. Filmes contendo 5 bicamadas de PAH e K(TPA)4[PW11O39Mn(OH2)] mostraram comportamentos similares referentes à queda da eletroatividade para arquiteturas iniciadas com PAH e PDMS. O filme com 5 bicamadas de PAH e K(TPA)4[PW11O39Mn(OH2)] iniciado com PAH não mostrou comportamento eletrocatalítico para a oxidação de triazinas. / In this work, self-assembled hybrid layer-by-layer films were prepared using Keggin type polyoxometalates, phosphotungstic acid (HPW) and the monolacunary complex K(TPA)4[PW11O39Mn(OH2)] alternated by a cationic polymer, poly(allylamine hydrochloride) (PAH). The film containing 5 bilayers of PAH and HPW deposited on a PDMS cushion exhibited better electrochemical behavior onto indium tin oxide (ITO) electrodes. So, this film was characterized by UV-vis spectroscopy, Fourier transformed infrared reflection adsorption spectroscopy (FT-IRRAS) and Surface Plasmon Resonance Spectroscopy (SPR). FT-IRRAS results showed that PDMS is going to the top of the bilayers of PAH and HPW when the film is prepared. Images of the Scanning Electronic Microscopy with field emission guns (FEG-SEM) confirm this fact. SPR spectroscopy results showed adsorption times of PAH and HPW short. Cyclic Voltammetry experiments with [Fe(CN)6]3- for the film confirm that it is porous. X-Ray Photoelectron spectroscopy (XPS) proved that in this film PDMS is present and it is responsible by protection against corrosion of substrate. This film can be used for environmental application. It was able to detect melamine and atrazine in concentrations of 4.10-8 and 1.10-6 mol.L-1 respectively. Films containing 5 bilayers of PAH and K(TPA)4[PW11O39Mn(OH2)] exhibited similar electrochemical behaviors for the decrease in the electroactivity for cushions of PAH and PDMS. The film with 5 bilayers of PAH and K(TPA)4[PW11O39Mn(OH2)] with PAH cushion does not exhibited electrocatalytic behavior for oxidation of triazines.

Neste trabalho, filmes híbridos produzidos pela técnica da automontagem eletrostática camada-por-camada foram preparados usando-se Polioxometalatos do tipo Keggin, ácido fosfotúngstico (HPW) e o complexo monolacunar K(TPA)4[PW11O39Mn(OH2)] alternados via um polímero catiônico, poli(cloreto de alilamônio) (PAH). O filme que continha uma pré-camada de adsorção de PDMS, juntamente com 5 bicamadas de PAH e HPW apresentou um melhor comportamento eletroquímico em filmes formados sobre óxido de índio e estanho (ITO). Em função disso, este filme foi caracterizado através de Espectroscopias de Absorção na região do Ultra-Violeta Visível (UV-vis), de Absorção-Reflexão na Região do Infra-vermelho (FT-IRRAS) e de Ressonância de Plásmons de Superfície (SPR). Foi constatado por FT-IRRAS que parte da camada de PDMS está se difundindo para a superfície quando as bicamadas de PAH e HPW vão sendo preparadas. Imagens de Microscopia Eletrônica de Varredura com Emissão de Campo (MEV-EC) confirmam esta hipótese. Espectroscopia de SPR indicou que tanto a adsorção de PAH quanto a de HPW ocorrem em tempos curtos. Experimentos de Voltametria Cíclica com [Fe(CN)6]3-mostraram que este filme é poroso. Resultados de Espectroscopia de Fotoelétrons Excitados por Raios X (XPS) comprovaram que PDMS protege o substrato contra corrosão. Esse mesmo filme pôde ser utilizado numa aplicação de caráter ambiental. Ele foi capaz de detectar melamina e atrazina em concentrações 4.10-8 mol.L-1 e 1.10-6 mol.L-1 respectivamente. Filmes contendo 5 bicamadas de PAH e K(TPA)4[PW11O39Mn(OH2)] mostraram comportamentos similares referentes à queda da eletroatividade para arquiteturas iniciadas com PAH e PDMS. O filme com 5 bicamadas de PAH e K(TPA)4[PW11O39Mn(OH2)] iniciado com PAH não mostrou comportamento eletrocatalítico para a oxidação de triazinas. / In this work, self-assembled hybrid layer-by-layer films were prepared using Keggin type polyoxometalates, phosphotungstic acid (HPW) and the monolacunary complex K(TPA)4[PW11O39Mn(OH2)] alternated by a cationic polymer, poly(allylamine hydrochloride) (PAH). The film containing 5 bilayers of PAH and HPW deposited on a PDMS cushion exhibited better electrochemical behavior onto indium tin oxide (ITO) electrodes. So, this film was characterized by UV-vis spectroscopy, Fourier transformed infrared reflection adsorption spectroscopy (FT-IRRAS) and Surface Plasmon Resonance Spectroscopy (SPR). FT-IRRAS results showed that PDMS is going to the top of the bilayers of PAH and HPW when the film is prepared. Images of the Scanning Electronic Microscopy with field emission guns (FEG-SEM) confirm this fact. SPR spectroscopy results showed adsorption times of PAH and HPW short. Cyclic Voltammetry experiments with [Fe(CN)6]3- for the film confirm that it is porous. X-Ray Photoelectron spectroscopy (XPS) proved that in this film PDMS is present and it is responsible by protection against corrosion of substrate. This film can be used for environmental application. It was able to detect melamine and atrazine in concentrations of 4.10-8 and 1.10-6 mol.L-1 respectively. Films containing 5 bilayers of PAH and K(TPA)4[PW11O39Mn(OH2)] exhibited similar electrochemical behaviors for the decrease in the electroactivity for cushions of PAH and PDMS. The film with 5 bilayers of PAH and K(TPA)4[PW11O39Mn(OH2)] with PAH cushion does not exhibited electrocatalytic behavior for oxidation of triazines.

Neste trabalho uretanas livres de isocianatos produzidas a partir de um precursor bis(ciclocarbonato) oligomérico contendo segmentos de poli(dimetil siloxano) (CCPDMS) foram sintetizadas. Para tal, utilizou-se diferentes aminas primárias como a 3-aminometil-3,5,5 trimetilciclohexilamina (IPDA) e as monoaminas 3-aminopropil(trietóxisilano) (APTES), feniletilamina (PEA), catecol amina (dopamina) e um decapeptídeo derivado da proteína de adesão de mariscos (mefp-1).O precursor oligomérico CCPDMS foi produzido por fixação de dióxido de carbono em anéis epóxi catalisado por um sal quarternário de amônio, o brometo de tetraetilamônio (BTA). O precursor CCPDMS foi então reagido com as aminas por meio de polimerização por abertura de anel formando hidroxiuretanas derivadas de PDMS (PDMSUr) com diferentes terminações de cadeia. Tendo como terminador de cadeia o APTES, foi possível produzir um material híbrido com domínios inorgânicos de sílica organicamente modificada (ormosil) interligadas com a parte orgânica de PDMS por meio de ligações uretana. Nesta matriz híbrida foram adicionadas diferentes porcentagens mássicas de ácido fosfotúngstico (PWA), variando entre 1% a 55%. Os materiais foram caracterizados quanto à sua estrutura química por técnicas espectroscópicas (Ressonância Magnética Nuclear, Infravermelho, Espectroscopia de Fotoelétrons, MALDI-ToF), propriedade anti-corrosão (espectroscopia de impedância eletroquímica, polarização potenciodinâmica), propriedades superficiais (energia livre superficial, nanoindentação), análise morfológica (Microscopia Eletrônica de Varredura), estabilidade térmica (Análise Termogravimétrica), testes de adesão (pull-off-test e cisalhamento), testes microbiológicos (adesão de bactérias, tecidos e citotoxicidade), além de ensaios de fotocromismo. O polioxometalato PWA conferiu propriedades fotocrômicas aos filmes híbridos de PDMSUr com máxima absorbância de 1,6 u.a após irradiação por luz ultra-violeta (UV). PDMSUr híbridas com ou sem PWA foram testadas como adesivos para vidro, alumínio, aço (SS316L) e liga de titânio (Ti6Al4V) apresentando valores de força de adesão entre 2-7 MPa. Filmes de PDMSUr preparados em diferentes substratos apresentaram comportamento bacteriostático frente à adesão de Escherichia coli (E.coli) e Lactobacillus casei (L.casei). A PDMSUr biomimética terminada por grupos catecóis foi capaz de formar camadas em superfícies metálicas apresentando boa estabilidade frente à remoção da camada depositada por lavagem com etanol. / Free isocyanate urethanes produced from an oligomeric precursor bis(cyclic carbonate) bearing poly(dimethylsiloxane) (CCPDMS) were synthesized in this work. Different primary amines such as 3-Aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA) and monoamines 3-aminopropyltriethoxysilane (APTES), phenylethylamine (PEA), catechol amine (dopamine) and a decapeptide derived from marine mussel foot protein (mefp-1). The precursor cyclic carbonate CCPDMS was obtained from carbon dioxide fixation into epoxy rings catalized by a quaternary ammonium salt, tetraethylamonium bromide (TEAB). The precursor CCPDMS was reacted with the different amines by ring opening polymerization affording the formation of hydroxyurethanes PDMS derived (PDMSUr) with different chain terminations. Using APTES as chain terminator was feasible to obtain a hybrid material containing inorganic domains of organically modified silica (ormosil) interconnected to the organic part PDMS through urethane bond. In this hybrid matrix different mass percentages, varying from 1%wt to 55 wt%, of phosphotungstic acid (PWA) were added. The materials were characterized regarding their chemical structure by spectroscopic techniques (Nuclear Magnetic Resonance, Infrared, and X-ray photoelectron spectroscopy), mass spectrometry (MALDI-ToF and GPC), anti corrosive property (Electrochemical Impedance Spectroscopy and potentiodynamic polarization), surface properties (free surface energy, nanoindentation), morphology (Scanning Electron Microscopy), thermal stability (Thermogravimetric analysis), adhesion strenght measurements (pull-off-test and lap-shear), microbiologic assays (bacteria adhesion, tissue adhesion and citotoxicity test) besides photochromic assays. The polyoxometalate PWA provided photochromic property to the PDMSUr hybrid films presenting a maximum absorbance of 1.6 a.u after ultraviolet (UV) irradiation. Hybrids PDMSUr with or without PWA were tested as adhesive for glass, aluminium, steel (SS316L) and titanium alloy (Ti6Al4V) showing adhesion strength values ranging from 2-7 MPa. PDMSUr films prepared on different substrates showed bacteriostatic behavior against Escherichia coli (E.coli) and Lactobacillus casei (L.casei). The biomimetic PDMSUr catechol endcapped was able to form a layer on metallic surfaces showing good stability after rinsing with ethanol.

A greater understanding of precessional dynamics in magnetic systems is central to several emerging technologies. This thesis presents the design, construction and development of a Vector Network Analyser based Ferromagnetic Resonance measurement instrument (VNA-FMR), and its application in characterising dynamic material properties in hybrid anisotropy [CoPd]8-NiFe films, produced by remote plasma sputtering. Potential applications for hybrid films include Spin Torque Oscillators (STOs) or Vortex Oscillators (VO) for use as microwave emitters in, for example in Microwave Assisted Magnetic Recording (MAMR). The VNA-FMR system was first used to measure thin films of NiFe (permalloy) which allowed its capabilities to be quantified and compared to systems reported in the literature. The instrument demonstrated the capability of measuring permalloy films down to a thickness of 3 nm and was used to measure resonance and damping behaviour which agreed well with theory. The results obtained forMs were in agreement with measurement using Vibrating Sample Magnetometry. The effect of interlayer exchange on FMR was explored in hybrid films using a sample series with varying Pd spacer layer thickness, t, [Co/Pd]-Pd(t)-NiFe. As Pd spacer thickness increased, a transition was observed from near complete coupling with a single resonance mode to separate acoustic and optical branches of resonance. As spacing was further increased, the branches converged towards the resonances of the individual component layers of the hybrid films. The results suggest exchange coupling has a range of less than 2 nm, and is completely extinguished at 5 nm, in agreement with previous measurements. However, a change in damping behaviour was observed between 10 and 20 nm spacer thickness, independent of field orientation.

Neste trabalho uretanas livres de isocianatos produzidas a partir de um precursor bis(ciclocarbonato) oligomérico contendo segmentos de poli(dimetil siloxano) (CCPDMS) foram sintetizadas. Para tal, utilizou-se diferentes aminas primárias como a 3-aminometil-3,5,5 trimetilciclohexilamina (IPDA) e as monoaminas 3-aminopropil(trietóxisilano) (APTES), feniletilamina (PEA), catecol amina (dopamina) e um decapeptídeo derivado da proteína de adesão de mariscos (mefp-1).O precursor oligomérico CCPDMS foi produzido por fixação de dióxido de carbono em anéis epóxi catalisado por um sal quarternário de amônio, o brometo de tetraetilamônio (BTA). O precursor CCPDMS foi então reagido com as aminas por meio de polimerização por abertura de anel formando hidroxiuretanas derivadas de PDMS (PDMSUr) com diferentes terminações de cadeia. Tendo como terminador de cadeia o APTES, foi possível produzir um material híbrido com domínios inorgânicos de sílica organicamente modificada (ormosil) interligadas com a parte orgânica de PDMS por meio de ligações uretana. Nesta matriz híbrida foram adicionadas diferentes porcentagens mássicas de ácido fosfotúngstico (PWA), variando entre 1% a 55%. Os materiais foram caracterizados quanto à sua estrutura química por técnicas espectroscópicas (Ressonância Magnética Nuclear, Infravermelho, Espectroscopia de Fotoelétrons, MALDI-ToF), propriedade anti-corrosão (espectroscopia de impedância eletroquímica, polarização potenciodinâmica), propriedades superficiais (energia livre superficial, nanoindentação), análise morfológica (Microscopia Eletrônica de Varredura), estabilidade térmica (Análise Termogravimétrica), testes de adesão (pull-off-test e cisalhamento), testes microbiológicos (adesão de bactérias, tecidos e citotoxicidade), além de ensaios de fotocromismo. O polioxometalato PWA conferiu propriedades fotocrômicas aos filmes híbridos de PDMSUr com máxima absorbância de 1,6 u.a após irradiação por luz ultra-violeta (UV). PDMSUr híbridas com ou sem PWA foram testadas como adesivos para vidro, alumínio, aço (SS316L) e liga de titânio (Ti6Al4V) apresentando valores de força de adesão entre 2-7 MPa. Filmes de PDMSUr preparados em diferentes substratos apresentaram comportamento bacteriostático frente à adesão de Escherichia coli (E.coli) e Lactobacillus casei (L.casei). A PDMSUr biomimética terminada por grupos catecóis foi capaz de formar camadas em superfícies metálicas apresentando boa estabilidade frente à remoção da camada depositada por lavagem com etanol. / Free isocyanate urethanes produced from an oligomeric precursor bis(cyclic carbonate) bearing poly(dimethylsiloxane) (CCPDMS) were synthesized in this work. Different primary amines such as 3-Aminomethyl-3,5,5-trimethylcyclohexylamine (IPDA) and monoamines 3-aminopropyltriethoxysilane (APTES), phenylethylamine (PEA), catechol amine (dopamine) and a decapeptide derived from marine mussel foot protein (mefp-1). The precursor cyclic carbonate CCPDMS was obtained from carbon dioxide fixation into epoxy rings catalized by a quaternary ammonium salt, tetraethylamonium bromide (TEAB). The precursor CCPDMS was reacted with the different amines by ring opening polymerization affording the formation of hydroxyurethanes PDMS derived (PDMSUr) with different chain terminations. Using APTES as chain terminator was feasible to obtain a hybrid material containing inorganic domains of organically modified silica (ormosil) interconnected to the organic part PDMS through urethane bond. In this hybrid matrix different mass percentages, varying from 1%wt to 55 wt%, of phosphotungstic acid (PWA) were added. The materials were characterized regarding their chemical structure by spectroscopic techniques (Nuclear Magnetic Resonance, Infrared, and X-ray photoelectron spectroscopy), mass spectrometry (MALDI-ToF and GPC), anti corrosive property (Electrochemical Impedance Spectroscopy and potentiodynamic polarization), surface properties (free surface energy, nanoindentation), morphology (Scanning Electron Microscopy), thermal stability (Thermogravimetric analysis), adhesion strenght measurements (pull-off-test and lap-shear), microbiologic assays (bacteria adhesion, tissue adhesion and citotoxicity test) besides photochromic assays. The polyoxometalate PWA provided photochromic property to the PDMSUr hybrid films presenting a maximum absorbance of 1.6 a.u after ultraviolet (UV) irradiation. Hybrids PDMSUr with or without PWA were tested as adhesive for glass, aluminium, steel (SS316L) and titanium alloy (Ti6Al4V) showing adhesion strength values ranging from 2-7 MPa. PDMSUr films prepared on different substrates showed bacteriostatic behavior against Escherichia coli (E.coli) and Lactobacillus casei (L.casei). The biomimetic PDMSUr catechol endcapped was able to form a layer on metallic surfaces showing good stability after rinsing with ethanol.

Submitted by Ariane de França Mescoloto null (rianefm@gmail.com) on 2017-02-25T15:53:15Z No. of bitstreams: 1 Dissertação_Ariane_2017.pdf: 4799231 bytes, checksum: 0e27c8b04f680e6a88f1e66a2df4e016 (MD5) / Approved for entry into archive by LUIZA DE MENEZES ROMANETTO (luizamenezes@reitoria.unesp.br) on 2017-03-07T14:05:43Z (GMT) No. of bitstreams: 1 mescoloto_af_me_araiq.pdf: 4799231 bytes, checksum: 0e27c8b04f680e6a88f1e66a2df4e016 (MD5) / Made available in DSpace on 2017-03-07T14:05:43Z (GMT). No. of bitstreams: 1 mescoloto_af_me_araiq.pdf: 4799231 bytes, checksum: 0e27c8b04f680e6a88f1e66a2df4e016 (MD5) Previous issue date: 2017-02-20 / Materiais híbridos orgânico-inorgânicos, constituídos pela combinação de componentes orgânicos e inorgânicos, são homogêneos, apresentam propriedades diferenciadas que refletem a natureza química dos componentes pelos quais foram formados, e são utilizados em diversas aplicações tecnológicas como catalisadores, sensores eletroquímicos, dispositivos ópticos e revestimentos protetores. Este trabalho foi realizado em duas etapas. Primeiramente, foi realizada a síntese e caracterização de um copolímero derivado do politiofeno, P(HTcoAAT), contendo ácido 3-tiofeno-acético (AAT) e 3-hexiltiofeno (HT), sintetizado via copolimerização oxidativa com cloreto férrico e caracterizado químico-estruturalmente por FTIR e RMN 1H e termicamente por TG/DTG. Em seguida, foram preparados filmes híbridos via sol-gel por spin-coating utilizando três óxidos inorgânicos: óxido de silício, titânio e zinco, os quais foram caracterizados opticamente por Espectroscopia no UV-vis e Fluorescência, e morfologicamente por AFM e MEV, além das caracterizações já citadas anteriormente. Os resultados químico-estruturais obtidos comprovaram a eficiência da metodologia usada para a preparação do copolímero e dos híbridos, permitindo a obtenção de matérias com propriedades ópticas interessantes. / Organic-inorganic hybrid materials, formed from organic and inorganic compounds combination, present specific properties that reflect the chemical nature of each precursor compound, and are used for several technological application such as catalists, electrochemical sensors, optical devices and barrier films. This work comprehends two steps: first of all the synthesis of a copolymer derived from polythiophene, P(HTcoTAA) containing 3-thiophene acetic acid (TAA) and 3-hexylthiophene (HT), it was performed from oxidative copolymerization with ferric chloride, and resulting materials characterized by FTIR and 1H NMR spectroscopy and TG/DTG thermal analyses. Following hybrid films from silicium, titanium and zinc oxides were prepared by sol-gel spin-coating and had its optical and morphological characteristics evaluated by UV-vis and Fluorescence spectroscopy, and AFM and SEM microscopy, besides the other characterization before cited. The obtained chemical-structural results show that the used methodology was efficient to prepare both the copolymer and the hybrids, allowing to materials presenting striking optical properties.

Les nanocristaux de cellulose (NCC) sont des nanoparticules biosourcées en forme de bâtonnets produites par l’hydrolyse à l’acide sulfurique de fibres de cellulose. Les nombreux avantages des NCC (excellentes propriétés mécaniques, faible densité, grande surface spécifique, non toxicité, source abondante et renouvelable) en font des briques élémentaires particulièrement attractives pour l’élaboration de nanocomposites biosourcés et expliquent l’intérêt croissant des mondes industriels et académiques pour ces nanoparticules. Au cours des dix dernières années, les NCC ont été associés à différents types de polymère pour former, grâce à la méthode d’assemblage couche par couche, des films minces aux architectures modulables. Dans ce travail, nous avons exploré trois axes de recherche innovants dans le domaine des films multicouches à base de NCC. Dans un premier temps, les chaînes de polymère ont été remplacées par des nanoparticules inorganiques de forme hexagonale chargée positivement, les nanoplaquettes de gibbsite (GN), pour former des films minces hybrides entièrement constitués de nanoparticules. Nous avons montré que l’architecture des films (NCC/GN) pouvait être modulée sur une large gamme en ajustant les paramètres physico-chimiques comme le facteur de forme, la force ionique de la suspension de NCC ou le protocole de séchage. La caractérisation fine de la structure interne des films a été déterminée par l’utilisation de deux techniques de surface complémentaires, la microscopie à force atomique (AFM) et la réflectivité des neutrons (RN). Nous avons pu prouver que l’architecture interne des films était le résultat de différentes forces d’interaction dont la portée dépend des paramètres physico-chimiques utilisés. Dans un second temps, la résistance à l’humidité de films entièrement biosourcés a été étudiée en comparant des films dans lesquels les NCC étaient associés soit à des chaines de xyloglucane (XG) natives soit à des chaines de XG oxydées. Les résultats d’AFM et de RN révèlent que les cinétiques d’absorption d’eau et l’hydratation des films dépendent fortement de la possibilité de créer des liaisons hémiacétales intra- et intercouches générant ainsi un réseau covalent. Le troisième axe de recherche concerne la production de surfaces macroscopiques au sein desquelles les NCC seraient orientés dans des directions privilégiées pour élaborer des nanocomposites anisotropes. Un alignement prononcé a été obtenu par l’utilisation d’un flux laminaire de cisaillement.L’ajustement des paramètres structuraux confère aux films multicouches des propriétés physiques macroscopiques spécifiques. Les propriétés mécaniques des films ont donc été déterminées en utilisant la technique SIEBIMM (strain induced elastic buckling instability for mechanical measurements) et ont été reliées aux paramètres structuraux. Ces nanocomposites aux architectures et propriétés modulables pourraient permettre la conception de films minces ou de revêtements intéressants pour des domaines tels que les membranes de séparation ou les supports flexibles pour l’électronique. / CNCs are biobased nanorods that are attracting increasing attention from both the academic and industrial communities due to their numerous properties such as renewability, high specific surface area, excellent mechanical properties, light weight, or non-toxicity. CNCs are thus considered as highly promising blocks for the production of high performance biobased composites. In the last ten years, negatively charged CNCs have been associated with natural or synthetic polycations or neutral biopolymers within multilayered films built by the layer-by-layer assembly technique. In the present study, we have investigated three new research axes in the CNC-based multilayers field. In a first part, polymer chains have been replaced by positively charged inorganic Gibbsite nanoplatelets (GN) to form innovative hybrid nanoparticules-based thin films. We have shown that the architecture of (CNC/GN) films can be tuned over a wide range by adjusting the physico-chemical parameters such as the aspect ratio of the CNC, the ionic strength, or the drying protocol. The detailed internal structure of the multilayered films has been elucidated by the complementary use of AFM and neutron reflectivity (NR) and was attributed to a combination of different interaction forces. In a second part, the resistance to humidity of purely biobased films was investigated by comparing films where CNCs are associated either with neutral xyloglucan chains or with oxidized ones. AFM and NR reveal that the kinetics of water intake and hydration strongly depends on the possibility to form inter- and intra-layer hemiacetal bonds forming a covalent network. The third axis concerns the production of uniformly oriented macroscopic surfaces of CNCs to build anisotropic multilayered nanocomposites. Enhanced alignment was achieved by the use of laminar shear flow.The fine tuning of the structural features of all the multilayered systems studied gives rise to specific macroscopic physical properties. The mechanical properties of films of various architectures (Young’s modulus) have thus been measured using the strain induced elastic buckling instability for mechanical measurements (SIEBIMM) technique and tentatively related to the film’s structure. The tunable properties of such multilayered systems pave the way to the design of thin films and coatings for separation membranes or supports for flexible electronics.

Optical properties of nanoscopic materials have been intensively perused over last couple of decades due to their tunable optical properties. Recent interests in this field have been mainly focused on the preparation of ordered arrays of nanoscopic materials and study of their optical properties. These interests have been motivated by the usability of such systems for nano photonic devices. Theoretical predictions from such systems reveal complex absorption and emission properties, different from individual ones mainly because of energy transfer between them. These properties can be controlled further by preparing hybrid arrays of nanostructures, including nano crystals of different types. Hybrid arrays with semiconducting quantum dots and metallic nanoparticles are an example of such system. Optical properties of such a system can be tuned by controlling the interaction between excitons and plasmons. This the-sis presents the experimental studies on optical properties of polymer capped polymer nanoparticles, quantum dot arrays and hybrid arrays with semiconducting quantum dot and metal nanoparticles. A brief summary of the experi-mental methods and results have been highlighted below. First chapter deals with the theoretical aspects of confined nanoscopic materials, especially describing the physics of zero dimensional systems and its optical properties. The discussions are mostly focused on two types of nano materials cadmium selenide (CdSe) quantum dot (QDs) and gold nano particles (Au NPs), used for the experimental study. Variation of energy levels of CdSe QDs and its absorption and emission properties under strong confinement regime has been discussed with respect to effective mass approximation (EMA) model. This is followed by the discussion on optical properties of Au NPs, describing absorption properties, based on Mie theory. Size dependent variation of absorption spectra of Au NPs and the modifications based on different models has been discussed. Second part of the chapter describes the physics of QD arrays and theory of exciton plasmon interactions based on the recent literatures. Energy transfer mechanism between semiconducting QDs and metal nanoparticles has been discussed based on numerical method and dipole approximation. Second chapter deals with the discussion on experimental techniques used for the study. Chapter 2 starts with the discussion on the synthesis method for CdSe QDs and Au NPs with different capping ligands. Preparation of QD ar-rays and hybrid arrays using self assembly technique has been discussed in this chapter. Preparation CdSe QD arrays and hybrid arrays with CdSe QDs and Au NPs using block copolymer (BCP) template and Langmuir Blodgett (LB) technique has been the main focus in the discussion. This is followed by the discussion on optical microscopy techniques, confocal, near field scanning microscopy (NSOM), Brewster angle microscopy and electron microscopy techniques, transmission electron microscopy and scanning electron microscopy. Studies on variation of band structure of small polymer capped Au NPs, with respect to the size and grafting density of the capping polymer is discussed in chapter 3. Polymer capped Au NPs with sizes 2-5 nm was used for the study. Dielectric constants of Au NPs were extracted from the absorption spectra by fitting the data using modified Mie theory. Dielectric constants of Au NPs were reproduced using an analytical expression, describing the contribution from different transitions in the optical regions. Results indicate systematic variations of the band structure with respect to the particle size and grafting density. The observations have been interpreted in terms of variation of co ordination number and chemical interaction of capping polymer with the surface atoms. Our new method analysis points to the importance of both quantum and surface effects in determining optical and electronic properties of polymer capped gold nanoparticles. Chapter 4 describes the study on morphology of the CdSe QD arrays prepared using different BCP templates and its correlation with optical properties. Spatially resolved spectra from the thin films of QD arrays were collected in near field and the compared with the spectra collected in far field. Spectra collected in near field mode shows sharp features in the emission spectra, possibly indicating the interaction of optical near field with QD excitation. It has been suggested that such fine structure could be induced by coupling between optical near filed and excitons and this coupling seems to be determined by local heterogeneity in QD density and disorder. Variation of exciton life time with respect to QD density and absorption spectra from the QD -BCP system is also described in chapter 4. Chapter 5 and 6 deals with the experimental studies on exciton -plasmon interaction in hybrid arrays of CdSe QDs and Au NPs. Emission properties hybrid arrays prepared using BCP templates has been the focus of chapter 5. Photoluminescence (PL) and lifetime measurements were performed on hybrid arrays and their variation with respect to the density and dispersion of Au NPs has been described. Optical measurements were performed on two sets of films using two different sizes of CdSe QDs, with the smaller QD emission overlapping with the plasmon resonance of Au NPs, while a red shifted emission peak for larger QDs. PL emission from hybrid arrays with smaller QDs shows en-hancement/quenching with respect to the dispersion of Au NPs, also showing systematic reduction of life time of CdSe QDs with Au NP density. Even though enhancement/quenching of emission properties of hybrid film with large QD shows similar behavior, PL decay measurements from such films shows non monotonic variation of exciton life time with respect to Au NP density. The enhancement/quenching behavior of the PL emission has been explained in terms of two competing mechanism, electromagnetic field enhancement and non radiative energy transfer. However to explain the energy transfer mechanism in hybrid arrays requires more systematic calculations. Chapter 6 describes the optical properties of highly compact hybrid arrays prepared using LB techniques. Hybrid arrays prepared at the air water inter-face were transferred to a glass substrates. The main focus on chapter 6 is to study the emission properties of highly compact hybrid arrays with respect to the spectral overlap between exciton energy of CdSe QDs and plasmon band of Au NPs with respect to their surface density (inter particle distance). Hybrid arrays were prepared with three types of QDs, with smaller QDs emission peak overlapping with plasmon band of Au NPs and clearly separated exciton and plasmon band for largest QDs. The PL emission from hybrid arrays with smaller QDs shows quenching, compared to strong enhancement in the emission from hybrid films with larger QDs. The disagreement of the observed results with respect to the theoretical calculations based on dipole approximation has been highlighted in the chapter. Chapter 7 includes the summary of the experimental results and the future works to be carried out as a continuation of the work presented in this thesis.