<div> <p><a>Polymer nanocomposites are envisioned for use in many advanced applications, such as structural industries, aerospace, automotive technology and electronic materials, due to the improved properties like mechanical strengthening, thermal and chemical stability, easy bulk processing, and/or light-weight instigated by the filler-matrix combination compared to the neat matrix. In recent years, due to increasing environmental concerns, many industries are inclining towards developing sustainable and renewable polymer nanocomposites. Cellulose nanomaterials (CNs), including cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs), have gained popularity due to their excellent mechanical properties and eco-friendliness (extracted from trees, algae, plants etc.). However, to develop CN-reinforced nanocomposites with industrial applications it is necessary to understand impact of hygroscopic swelling (which has very limited </a>quantitative study at present), aspect ratio, orientation, and content of CNs on the overall performance of nanocomposites; and overcome the low dispersibility of CNs and improve their compatibility with hydrophobic matrix. In this work, we attempt to understand the influence of single nanocrystals in the hygroscopic and optical response exhibited by nanostructured films; effect of CNCs on the properties of PVA/CNC fibers by experimental evidence with mathematical modeling predictions; and hydrophobized CNFs using a facile, aqueous surface modification to improve interfacial compatibility with epoxy. </p><p><br></p> <p>To evaluate the effect of CNC alignment in the bulk response to hygroscopic expansion, self-organized and shear-oriented CNC films were prepared under two different mechanisms. The coefficient of hygroscopic swelling (CHS) of these films was determined by using a new contact-free method of Contrast Enhanced Microscopy Digital Image Correlation (CEMDIC) that enabled the characterization of dimensional changes induced by hygroscopic swelling of the films. This method can be readily used for other soft materials to accurately measure hygroscopic strain in a non-destructive way. By calculating the CHS values of CNC films, it was determined that hygroscopic swelling is highly dependent on the alignment of nanocrystals within the films, with aligned CNC films showing dramatically reduced hygroscopic expansion than randomly oriented films. Finite element analysis was used to simulate moisture sorption and kinetics profile which further predicted moisture diffusion as the predominant mechanism for swelling of CNC films. </p> <p><br></p><p>To study the effects of different types and aspect ratios of CNCs on mechanical, thermal and morphological properties of polyvinyl alcohol (PVA) composite <a>fibers, CNCs extracted from wood pulp and cotton were reinforced into PVA to produce fibers by dry-jet-wet spinning. The fibers were collected as-spun and with first stage drawing up to draw ratio 2. </a>The elastic modulus and tensile strength of the fibers improved with increasing CNC content (5 – 15 wt. %) at the expense of their strain-to-failure. The mechanical properties of fibers with cotton CNC were higher than the fibers with wood CNC when the same amount of CNCs were added due to their higher aspect ratio. The degree of orientation along the spun fiber axis was quantified by 2D X-ray diffraction. As expected, the CNC orientation correlates to the mechanical properties of the composite fibers. Micromechanical models were used to predict the fiber performance and compare with experimental results. Finally, surface and cross-sectional morphologies of fibers were analyzed by scanning electron microscopy and optical microscopy.</p><p><br></p> <p>To improve the dispersibility and compatibility of CNFs with epoxy, CNFs were modified by using a two-step water-based method where tannic acid (TA) acts as a primer with CNF suspension and reacts with hexadecylamine (HDA), forming the modified product as CNF-TA-HDA. The modified (-m) and unmodified (-um) CNFs were filled into hydrophobic epoxy resin with a co-solvent (acetone), which was subsequently removed to form a solvent-free two component epoxy system, followed by addition of hardener to cure the resin. Better dispersion and stronger adhesion between fillers and epoxy were obtained for m-CNF than the um-CNF, resulting in better mechanical properties of nanocomposites at the same loading. Thermal stability and the degradation temperature of m-CNF/epoxy improved when compared to neat epoxy. </p> </div> <br>

We present the synthesis and characterisation of novel single organic molecules known as phenoxylene borazines and borazatruxenes. Using temperature-dependant and concentration-dependant 1H NMR, we probe the supramolecular aggregation of these molecules in solution. Finally, we synthesise 2D hybrid material comprised of electron delocalised benzene rings and electron localised borazine rings. Using a combination of solid-state 11B and 13C NMR techniques, Raman spectroscopy and XPS, we confirm the presence of benzene and borazine regions in these novel materials.

O presente trabalho de Doutorado tem como objetivo investigar a influência de materiais lamelares prístinos e modificados e a influência de diferentes rotas sintéticas nas propriedades físico-químicas do amido termoplástico, utilizando glicerol como plastificante. Para tanto, empregou-se para a produção dos materiais híbridos uma argila sintética da família das hectoritas (Laponita RD) na forma prístina e também modificada com íons berberine e carnosina, além de um hidróxido duplo lamelar (HDL) constituído por íons Zn2+/Al3+ intercalado com carboximetilcelulose (CMC). O amido e o material lamelar foram combinados, utilizando as metodologias de casting e extrusão, nas concentrações de 2,5 e 5,0 % (m/m) de argila ou HDL com relação ao polissacarídeo. Já quantidade de plastificante empregada foi variável, dependendo da rota de preparação empregada, sendo de aproximadamente 20 % (m/m) via casting e 30 % (m/m) via extrusão com relação ao amido. Conforme mostram os difratogramas de raios X dos filmes obtidos pelo método casting, todos os filmes contendo argila em sua composição exibem um sinal largo de difração na região de baixo ângulo de 2&#952;, embora pouco intenso, indica a existência de certa quantidade de nanocompósito do tipo intercalado. Já para os materiais obtidos via extrusão, os sinais de difração em baixo ângulo são consideravelmente alargados e muito pouco intensos. A propriedade térmica do amido termoplástico foi piorada em todos os casos estudados nos materiais contendo argila ou HDL em sua composição. A presença de carga inorgânica na formulação dos materiais híbridos preparados não retardou o processo de decomposição não-oxidativo do amido. A presença de uma maior quantidade de glicerol nos materiais obtidos por extrusão resultou em uma antecipação ainda maior no principal evento de perda de massa, em comparação com os mesmos materiais obtidos via casting. Devido à alta característica hidrofílica do amido, materiais lamelares intercalados com espécies que possuem maior caráter hidrofílico, como a Laponita prístina (contendo apenas íons Na+) e a carnosina mostraram uma melhor dispersão pela matriz polimérica, através da análise por técnicas de microscopia. Adicionalmente, observou-se uma melhor homogeneidade de distribuição da fase lamelar na fase polimérica nos filmes obtidos por casting em comparação com os materiais obtidos por extrusão. Os resultados mecânicos de todos os materiais híbridos analisados mostram tendências pouco conclusivas com relação ao amido termoplástico. Em geral, observa-se uma melhora muito sutil na máxima resistência a tração com a presença de material lamelar na composição dos materiais testados, além de uma diminuição na elongação máxima. Da mesma forma, a permeabilidade a gases dos filmes contendo argila ou HDL em sua composição mostrou resultados pouco conclusivos com relação ao amido termoplástico, geralmente exibindo uma redução modesta na permeabilidade. A investigação do perfil de biodegradação dos materiais contendo fase lamelar em sua composição mostrou que apenas a amostra contendo Laponita modificada com carnosina obtida por extrusão foi capaz de retardar significativamente a conversão do carbono das cadeias poliméricas em CO2, com relação ao amido termoplástico. / This present Thesis aimed to investigate the influence of pristine and modified layered materials and the influence of different preparation routes on the physicochemical properties of thermoplastic starch, using glycerol as plasticizer. To reach this goal, it was used to produce hybrid materials a synthetic clay belonging to the hectorite family (Laponite RD) in both pristine form and modified with berberine and carnosine ions and also a layered double hydroxide (LDH) comprised of Zn2+/Al3+ ions intercalated with carboxymethylcellulose (CMC). Both starch and the layered material were combined using casting and extrusion methodologies, using concentrations of 2.5 and 5.0 % (w/w) of clay or LDH relative to starch. The amount of plasticizer utilized was variable, depending on the preparation route employed. It was used approximately 20 % (w/w) of glycerol on casting route and 30 % (w/w) on extrusion route relative to starch. According to X ray diffractograms of the films obtained by casting route, all hybrid films that contain clay in their composition exhibit a large diffraction signal at low 2&#952; angle values, albeit its low intensity, indicates the existence of a certain contribuition of a intercalated nanocomposite. On the other hand, the hybrid materials obtained through extrusion method, these low angle diffraction signals are very broad and possess very low intensity. The thermal properties of thermoplastic starch were worsened in all studied cases after combined with clay or LDH. The presence of inorganic filler on the formulation of hybrid materials does not postpone the beginning of the non-oxidative decomposition process of starch. A higher amount of glycerol on the final materials obtained through extrusion resulted in an even greater anticipation on the main mass loss event in comparison to the analogous materials obtained using casting technique. Due to the high hydrophilic nature of starch, layered materials intercalated with ionic species that show higher hydrophilicity such as pristine Laponite (containing solely Na+ ions) and carnosine exhibited better dispersion through the polymer matrix, after being analyzed with microscopic techniques. Additionaly, it was observed a higher homogeneity of distribution of the layered phase over the polymer phase on the films obtained through casting in comparison to the materials obtained through extrusion. The tensile tests of all analyzed hybrid materials show a poorly conclusive trend in comparison to thermoplastic starch. In general, it was observed a subtle improvement on the maximum tensile strength of the materials containing layered material in their composition and also a decrease in the maximum elongation. In a same trend, gas permeability of the films was poorly conclusive in comparison to thermoplastic starch, generally resulting in a subtle reduction of permeability values. The investigation of biodegradation profile of the materials containing inorganic filler show that only Laponite modified with carnosine ions was able to postpone significatively the conversion of carbon from the polymer chains to CO2 in comparison to thermoplastic starch.

Estudos sobre a inserção de complexos oxindolimínicos de cobre(II) ou zinco(II) em argilas sintéticas beidelitas foram desenvolvidos visando obter carregadores inorgânicos capazes de promover a liberação modificada de metalofármacos. Investigações anteriores mostraram que os complexos estudados são promissores agentes antitumorais. São capazes de se ligar ao DNA, nas alças menor ou maior dependendo do ligante, causando danos oxidativos através da formação de espécies reativas de oxigênio (EROs), especialmente radicais hidroxil, no caso de complexos de cobre, que apresentam atividade redox. Também interagem com mitocôndrias levando a uma diminuição do potencial de membrana e atuando como agentes desacopladores. Constituem assim compostos indutores de apoptose ou morte celular programada. Adicionalmente inibem proteínas envolvidas no ciclo celular, como topoisomerase I humana e quinases dependentes de ciclina (CDK1 e CDK2). As beidelitas foram sintetizadas e caracterizadas por métodos já descritos na literatura. Posteriormente, em presença dos complexos, formaram materiais híbridos do tipo beidellita/[complexo]. A caracterização das argilas e dos materiais híbridos obtidos foi realizada usando diferentes técnicas: espectroscopias UV/Vis, IV e EPR, análise termogravimétrica, difratometria de raios X. Na caracterização dos complexos utilizou-se ainda espectrometria de massas (ESI-MS). Os materiais híbridos preparados mostraram-se estáveis e capazes de inviabilizar células tumorais (HeLa), no caso dos materiais híbridos com compostos de cobre(II), com IC50 na faixa de 0,11 a 0,41 mg/mL. Ao contrário, os compostos análogos de zinco(II) e as argilas puras mostraram-se não-tóxicas frente às mesmas células. Os resultados obtidos indicam uma promissora possibilidade de uso das beidellitas como carregadores destes complexos metálicos. / Studies on the insertion of oxindolimine complexes of copper(II) or zinc(II) in synthetic beidellites clays have been developed to obtain an inorganic support capable of promoting the modified-release of metallopharmaceuticals. Previous investigations have shown that the studied complexes are promising antitumor agents. They are able to bind to DNA, in the minor or major groves, causing oxidative damage via formation of reactive oxygen species (ROS), especially hydroxyl radicals, in the case of copper complexes, which have redox properties. They also interact with mitochondria leading to a decrease of membrane potential and acting as decoupling agent. Thus, these compounds can induce apoptosis or programmed cell death. Additionally, they inhibit proteins involved in the cell cycle, such as human topoisomerase I and cyclin dependent kinases (CDK1 and CDK2). The beidellites were synthesized and characterized by methods described in the literature. Additionally, in the presence of these complexes were obtained hybrid materials type beidellita/[complex]. The characterization of clays and the obtained hybrid materials were performed using different techniques: spectroscopy UV/Vis, IR and EPR, thermogravimetric analysis, X-ray powder diffraction. In the characterization of the complexes mass spectrometry (ESI-MS) was also used. The prepared hybrid materials were stable and able to derail tumor cells (HeLa) in the case of hybrid materials with copper(II) compounds, with IC50 in the range from 0.11 to 0.41 mg/mL. Unlikely, the analogous compounds of zinc(II) and pure clays have proved to be non-toxic facing the same cells. These results indicate a promising possibility of using the beidellites as carriers of these antitumor metal complexes

<p>The thesis covers the following topics:</p> <p>1. aggregation and size effect on metal-polymer nanocomposite thermal interface materials</p> <p>2. diffusion limited cluster aggregation lattice simulation on thermal conductivty</p> <p>3. thermal interfacial resistance reduction between metal and dielectric materials by inserting an intermediate metal layer</p> <p>4. absence of coupled thermal interfaces in al2o3/ni/al2o3 sandwich structure</p> <p>5. ultra-efficient low-cost radiative cooling paints</p>

Ce travail de thèse porte sur l’élaboration de microgels biocompatibles et multi-stimulables à base de méthacrylate d’oligo(éthylène glycol) et de nanoparticules d’oxyde de fer. Des microgels sensibles au pH, à la température et au champ magnétique ont été élaborés au cours de cette étude via une stratégie multi-étape partant de : 1. la synthèse et la caractérisation de microgels pH- et thermosensibles à base d’oligo(éthylène glycol), 2. l'élaboration de microgels hybrides par imprégnation de nanoparticules magnétiques au sein des microgels d’oligo(éthylène glycol). L’étude de la synthèse des microgels et de leurs propriétés physico-chimiques a permis de mettre en avant l’effet important de la structure interne des microgels sur leurs propriétés de gonflement/contraction. La caractérisation des microgels hybrides a mis en évidence l’importance des fonctions acide carboxylique réparties de manière homogène au sein des microgels, le tout permettant d’encapsuler efficacement et de manière homogène des nanoparticules magnétiques tout en préservant les propriétés colloïdales et thermo-stimulables des microgels hybrides. Enfin des films structurés constitués de multicouches de microgels ont ainsi pu être élaborés via un procédé simple de séchage de dispersion aqueuse de microgels. Une étude prospective des propriétés optique et mécanoélectrique de films auto-assemblés de microgels d’oligo(éthylène glycol) hybride et non hybride par évaporation de solvant a permis de mettre en évidence le rôle positif des groupements ioniques issus des fonctions carboxylates sur le potentiel électrique induit lors de la compression des films. / Smart polymer materials can provide wide range of options to induce advanced functional features and relevant surface properties in one material. This all-in-one concept is of great interest for applications that require several simultaneous treatments such as cosmetic application. Herein, we aim to develop oligo(ethylene glycol)-based biocompatible multiresponsive microgels that could both interact on the skin as smart drug delivery system (DDS) while fulfilling advanced properties such as surface protection, mechanical and optical properties. Specifically, aqueous dispersed microgels responsive to pH, temperature and magnetic field were synthesized via multi-step strategy: 1. The synthesis and characterization of pH- and thermo-responsive oligo(ethylene glycol)-based microgels by precipitation polymerization, 2. The encapsulation of pre-formed magnetic nanoparticles via adsorption of the nanoparticles into the multiresponsive microgels. The effect of the microgel microstructure on their pH- and thermo-responsive properties were highlighted thanks to a rational investigation of the crosslink density and acid-functional units distribution within the microgels. Oligo(ethylene glycol)-based microgels with homogeneous distribution of both acid-functional unit and crosslinker allowed the synthesis of highly pH-and thermo-responsive microgels. The hybrid microgels prepared by straightforward encapsulation of pre-formed magnetic nanoparticles were characterized. The homogeneous microstructure of the initial stimuli-responsive biocompatible microgels plays a crucial role for the design of unique well-defined ethylene glycol-based thermoresponsive hybrid microgels. Thus, robust monodisperse thermoresponsive magnetic microgels were produced, exhibiting both a constant value of the swelling-to-collapse transition temperature and good colloidal stability whatever the NPs content. These smart microgels can spontaneously form a transparent film with perfect arrangement of the microgels by simple solvent evaporation process. The characterization of the optical and mechanoelectrical properties of the self-assembled microgel films were performed. We highlighted that the presence of anionic charges inside the microgels emphasizes the mechanoelectrical effect of the films.

Depuis plusieurs dizaines d'années, les matériaux hybrides organiques-inorganiques constituent une classe de matériaux particulièrement bien adaptée aux applications en optique intégrée. Le réseau minéral, élaboré par procédé sol-gel, confère au matériau la tenue mécanique. Quant au réseau organique, qui est réticulable par voie photochimique, il permet la formation des systèmes guidants. Des travaux antérieurs réalisés au sein de notre laboratoire ont montré le potentiel d'un matériau à base d'un précurseur hybride 2-(3,4 epoxycyclohexylethyltrimethoxysilane) (EETMOS) pour l'application en optique intégrée. Bien que la qualité des composants réalisés à 1,31µm se soit révélée satisfaisante, un problème subsiste : une trop forte atténuation à 1,55 µm. La transmission optique autour de ces longueurs d'ondes est limitée par la présence des groupements OH et CH aliphatiques.L'objectif principal de ce travail est de développer une nouvelle génération de matériaux hybrides avec une très grande réactivité et de diminuer la quantité de groupements impliqués dans l'atténuation. Nous avons choisi la fonction vinyl éther comme fonction organique grâce à sa grande réactivité par voie cationique en comparaison avec la fonction époxyde. Nous avons étudié la double fonctionnalité de polymérisation du nouveau matériau hybride à base d'un vinyl éther silane. En premier lieu, les réactions d'hydrolyse et de polycondensation du sol ont été suivies par la spectroscopie RMN liquide du Si-29 en fonction du temps, de la température et du pH de l'eau impliquée dans l'hydrolyse. Le but était d'obtenir le plus haut taux d'oligomère multifonctionnel possible et le minium de groupement OH. La photopolymérisation de type cationique de la fonction vinyl éther a ensuite été étudiée, en utilisant la spectroscopie d'absorption dans l'infrarouge moyen. En présence du photoamorceur diaryliodonium, la photopolymérisation a été étudiée en suivant l'évolution de la bande d'absorption de la double liaison vinyl éther avant et après irradiation. La photopolymérisation cationique est rapidement initiée dès le début de l'exposition aux UV, ce qui prouve la réactivité important de la fonction vinyl éther. En utilisant la spectroscopie d'absorption dans le proche infrarouge, les résultats montrent des niveaux d'atténuation très prometteurs pour l'utilisation de ce matériau en optique intégré à 1,31 et 1,55 µm. / In the last few years, organic-inorganic hybrid materials were particularly attractive for integrated optical circuits. Hybrid network could be prepared by the formation of inorganic and organic network simultaneously through sol-gel technique and photopolymerization process.A composition based on [2-(3, 4 epoxycyclohexylethyltrimethoxysilane)] has already allowed the fabrication of optical integrated devices. The organic polymerization is on a cationic way. Results show the contributions of OH and aliphatic CH groups to the attenuation in the third telecommunication window located at 1,55 µm.The main objective of this work is to remove this difficulty by developing a new generation of hybrid materials with a very high reactivity and low amount of groups involved in the attenuation. We have chosen vinyl ether function as an organic part because of their well known high polymerization rates via cationic way which are faster than the epoxide function and which lead to no OH groups generation and a very low aliphatic CH groups introduction.In this work, we study the dual functional structure of a new vinyl ether alkoxysilane hybrid precursor. Firstly, hydrolysis and polycondensation of vinyl ether based solution are followed by liquid and solid Si-NMR spectroscopy. The kinetic reaction is followed as a function of time, temperature and pH of the water involved in the hydrolysis, in order to obtain the highest reactive multifunctional oligomer and the lowest OH groups. Secondly, results of the cationic photopolymerization of vinyl ether- based monomers are also reported, using middle infrared spectroscopy. In the presence of diaryliodonium photoinitator, the photopolymerization is studied by monitoring the absorption band of vinyl ether double bond before and after irradiation. The cationic photopolymerization occurs rapidly upon UV-exposure and vinyl ether monomers proved to be very effective monomers. Using near infrared spectroscopy, results show promising attenuation for the use of this material in integrated optic at 1,31 µmand 1,55 µm.

Neste trabalho focou-se na preparação de materiais com aplicação em processos de tratamento de compostos orgânicos poluentes. Especificamente, buscou-se correlacionar as propriedades físicas e químicas dos materiais com as suas respostas catalíticas nos processos de fotocatálise heterogênea e de ozonização. Empregando-se o método de precipitação, preparou-se óxidos mistos de TiO2 e CeO2 em diferentes proporções. A caracterização destes materiais mostrou uma correlação entre a formação de partículas anisotrópicas, com morfologia do tipo bastão, e a capacidade de degradação de fenol pelo processo de fotocatálise heterogênea. Em particular, obteve-se 70% de degradação de fenol para o material com 20% CeO2. A interação entre o TiO2 e CeO2 também foi estudada em materiais preparados pelo método sol-gel. A presença do CeO2 retardou a transformação do polimorfo anatásio para rutilo, bem como manteve a estrutura de poros quando os matareriais foram calcinados a 650 ºC. Esta maior estabilidade possui relação com as propriedades fotocatalíticas dos materiais calcinados. Degradou-se 77% de fenol com o fotocatalisador 0,5% CeO2. Fotocatalisadores híbridos de SiMgOx e TiO2 foram preparados pela deposição de diferentes quantidades de TiO2 em placas de sepiolitas por slip-casting. Avaliou-se os materiais híbridos na degradação de ar contaminado com tricloroetileno (TCE) pelo processo de fotocatálise heterogênea. Observou-se uma dependência entre a espessura da camada de TiO2 e a taxa de degradação e mineralização do TCE, obtendo-se até 100% de degradação do TCE. Os materiais híbridos também tiveram suas propriedades catalíticas avaliadas na fotodegradação de TCE utilizando radiação solar. A combinação das propriedades de adsorção da sepiolita e fotocatalíticas do TiO2 possibilitaram 100% de degradação do TCE via incidência de radiação solar. O estudo de materiais híbridos também foi realizado com a preparação de esferas híbridas de carbono e CeO2. Este novo material foi preparado em uma única etapa, pelo método hidrotermal, sem a necessidade de emprego de solventes orgânicos. As esferas híbridas foram aplicadas na degradação de solução aquosa de ácido salicílico pelo processo de ozonização. As esferas eram, possívelmente, formadas por um core de carbono com nanopartículas de CeO2 dispersas em sua superfície hidrofílica. O efeito sinérgico entre a estrutura de carbono e o CeO2 resultou em um aumento de 25% na mineralização da solução de ácido salicílico pelo processo de ozonização. / This study was focused on the preparation of materials applied to the treatment of organic pollutant compounds. The main idea was to correlate the physical and chemical properties of these materials with their catalytic responses in heterogeneous photocatalysis and ozonation processes. Using the precipitation method, TiO2 and CeO2 mixed oxides were prepared in different proportions. The characterization of these materials showed a correlation between the formation of anisotropic rod-like particles and the capacity of degradation of phenol by a heterogeneous photocatalysis process. It was actived 70% of phenol degradation using the material with 20% CeO2. The interaction between TiO2 and CeO2 was also studied in materials prepared by the sol-gel method. The presence of CeO2 retarded the transition from anatase to rutile polymorphic, as well as maintained the porous structure when the materials were calcinated at 650 ºC. This major stability is related to the photocatalytic properties of the calcinated materials. For instance, 77% of the phenol was degraded using the 0.5% CeO2 photocatalyst. Hybrid photocatalysts composed by SiMgOx and TiO2 were prepared by depositing different amounts of TiO2 on sepiolite plates by slip-casting method. The performances of hybrid materials were evaluated by the degradation of contaminated air with trichloroethylene (TCE) using the heterogeneous photocatalysis process. A correlation between the thickness of the TiO2 layer and the degradation and mineralization rates of TCE was observed, obtaining up to 100% degradation of the TCE. Also, the catalytic properties of the hybrid materials were evaluated by TCE photodegration using solar radiation. A combination of the adsorption properites of the sepiolite and the photocatalytic properties of TiO2 allowed up to 100% of TCE degradation under incidence of solar radiation. The study of hybrid materials was also carried out with the preparation of carbon and CeO2 hybrid spheres. This novel material was prepared in one-pot step, using the hydrothermal method, without organic solvents. The hybrid spheres were used in the degradation of aqueous solution of salicylic acid by the ozonization process. The spheres were possibly formed by a core containing carbon with CeO2 nanoparticles dispersed on their hydrophilic surface.The synergetic effect between the carbon structure and the CeO2 resulted in an increase of 25% in the salicylic acid solution mineralization.

<p>Strukturiranje elastomernih kompozita dodavanjem različitih vrsta nanopunila je dovelo do značajnog pobolj&scaron;anja njihovih primenskih svojstava, a samim tim i do povećanja njihove potencijalne primene kao pogodnih materijala za specijalne namene. U ovom radu, dobijene su dve grupe elastomernih hibridnih materijala za specijalne namene (na osnovu stirenbutadienskog elastomera i na osnovu termoplastičnih poliuretana).<br />U prvom delu istraživanja, veliki doprinos u razvoju industrije gume je postignut strukturiranju stirenbutadienskih nanokompozita primenom nanočestica punila silicijum(IV)oksida različitih morfolo&scaron;kih svojstava, dobijenih hidrotermičkom i termičkom obradom, primenom tri eksperimentalno modelovana punila silicijum(IV)oksida (dobijena taloženjem iz Na-vodenog stakla sa sumpornom kiselinom), kao i hibridnog punila (kombinacije čestica aktivne čađi i SiO₂ optimalnih svojstava). Izvr&scaron;ena je analiza uticaja strukture, povr&scaron;ine i povr&scaron;inske aktivnosti nanopunila na ojačanje elastomera, kao i provera koncepata, modela i teorija ojačanja na neumreženim i umreženim sistemima stirenbutadienskih elastomera ojačanih modifikovanim punilima SiO₂. Primenom mnogobrojnih metoda karakterizacije, sveobuhvatno je ispitan uticaj nanopunila na karakteristike me&scaron;anja, reolo&scaron;ka svojstva pripremljenih hibridnih nanokompozita, sposobnost umrežavanja u neumreženom materijalu, kao i na toplotna, dinamičko-mehanička i mehanička svojstva umreženih nanokompozita, radi projektovanja i optimizovanja sastava SBR hibridnih materijala za razvoj modelnog protektora sa optimalnim svojstvima za ekolo&scaron;ke ili &quot;zelene pneumatike&quot;. Drugi deo istraživanja je bio posvećen dobijanju segmentiranih poliuretanskih elastomernih nanokompozita primenom alifatičnih polikarbonatnih diola i nanočestica bentonita, koji nalaze primenu u medicini, građevinarstvu, u industriji name&scaron;taja i sportske opreme. Primenom mnogobrojnih metoda za karakterizaciju, ispitan je složen mehanizam uticaja tvrdih segmenata, termodinamičke nekompatibilnosti i prisustva nanočestica punila bentonita na strukturu i morfologiju, kao i na toplotna i dinamičko-mehanička svojstva pripremljenih poliuretanskih termoplastičnih elastomera. Dobijeni podaci o obrazovanju vodoničnih veza, termičkoj stabilnosti i termičkoj dekompoziciji, kao i o temperaturama prelaska u staklasto stanje i oblasti raskidanja čvorova fizičkih veza, predstavljaju značajan doprinos napretku strukturiranja poliuretanskih elastomera i nanokompozita na osnovu alifatičnih polikarbonatnih diola, i omogućavaju primenu ovih materijala za specijalne namene.</p> / <p>The structuring of elastomeric composites by addition of different nanofillers has led to a significant improvement of their end-use properties, and therefore, to their potential application as suitable materials for special applications. In this work, two types of elastomeric hybrid materials for special purposes were obtained (based on styrene-bustadiene elastomer or on segmented thermoplastic polyurethanes).<br />In the first part of the study, a major contribution to the development of the rubber industry was achieved by structuring styrene-butadiene nanocomposites, applying silica nanoparticles of various morphological properties: prepared by hydrothermal or thermal treatment, three experimentally prepared SiO2 fillers (obtained by precipitation from sodium silicate with sulfuric acid), as well as a hybrid filler (combination of carbon black and SiO2 fillers with optimal properties). The analysis of the influence of the nanoparticles structure, surface and surface activity on the reinforcment of SBR elastomers, as well as the verification of concepts, models and reinforcement theories on non-cross-linked and cross-linked systems of styrene-butadiene nanocomposites was performed. Using the numerous characterization methods, the influence of nanofillers on the mixing characteristics, the rheological properties of the prepared hybrid nanocomposites, as well as the thermal, dynamic-mechanical and mechanical properties of cross-linked SBR nanocomposites was studied, in order to design and optimize the composition of SBR hybrid materials for development of environmental friendly or &quot;green&quot; tyre protector model.<br />The second part of the research was devoted to the preparation of segmented polyurethane elastomeric nanocomposites using aliphatic polycarbonate diols and bentonite nanoparticles, that have found the significant application in the medicine, construction, the furniture and sports equipment industry. Applying numerous characterization methods, a complex mechanism of the influence of the hard segments, thermodynamic incompatibility and the presence of bentonite filler on the structure and morphology, as well as on the thermal and dynamic-mechanical properties of the synthesized thermoplastic elastomers was studied. The obtained data on the hydrogen bonds formation, thermal stability and thermal decomposition, as well as the glass transition temperature and physical crosslink disruption temparature range, makes a significant contribution to the progress in structuring of polycarbonate-based polyurethane elastomers and their hybrid materials, and improves their potential applications for the special purposes.</p>

<p>U ovom radu, sintetisani su poli(uretan-izocijanuratni) elastomeri sa kovalentnim<br />čvorovima, katalitičkom ciklotrimerizacijom teleheličnih diizocijanata kao prekursora mreže<br />na osnovu 2,4-toluen-diizocijanata, &alpha;,&omega;-dihidroksipoli(oksipropilen)diola i monoola<br />dietilenglikolmonometiletra. Dobijeni su i termoplastični segmentirani poliuretani, sa<br />čvorovima fizičkog umreženja, jednostepenim postupkom i metodom prepolimerizacije,<br />reakcijom dve vrste alifatskog polikarbonatnog diola, koji se razlikuju u strukturi lanca,<br />heksametilen-diizocijanata i produživača lanca (1,4-butandiola). Sintetisana je i serija<br />poliuretanskih hibridnih materijala, dodatkom 1% <em>m/m</em> nanočestica organski modifikovanih<br />glina (montmorilonita i bentonita). Prioritet rada je bio da se utvrdi uticaj udela elastično<br />aktivnih i visećih lanaca na dinamičko-mehanička svojstva, toplotnu stabilnost i svojstva<br />prigu&scaron;enja poliuretanskih mreža sa izocijanurat (heksahidro-1,3,5-triazin-2,4,6-trion)<br />prstenovima, kao čvorovima. Takođe, cilj istraživanja je bio da se ispita uticaj odnosa<br />reaktivnih grupa diizocijanata, polikarbonatne komponente i produživača lanca, kao i dodatka nanočestica na svojstva povr&scaron;ine, morfologiju, dinamičko-mehanička i toplotna svojstva segmentiranih neojačanih i ojačanih elastomera. Toplotna degradacija poli(uretanizocijanuratnih) mreža i segmentiranih termoplastičnih poliuretana praćena je neizotermskim ispitivanjima, koristeći istovremenu termogravimetrijsku i masenu analizu (TG-MS), kao i istovremenu termogravimetriju i diferencijalno skenirajuću kalorimetriju (TG-DSC). Viskoelastična svojstva i svojstva prigu&scaron;enja dobijenih poliuretanskih elastomera su ispitivana pomoću dinamičko-mehaničke analize (DMA). Toplotno pona&scaron;anje segmentiranih poliuretana i nanokompozita, dobijenih jednostepenim postupkom sinteze, je proučavano modulovanom diferencijalno skenirajućom kalorimetrijom (MDSC). Temperatura prelaska u staklasto stanje i termoplastična svojstva neojačanih i ojačanih poliuretanskih materijala, dobijenih postupkom prepolimerizacije, određeni su primenom diferencijalno skenirajuće kalorimetrije (DSC). Hemijska struktura i formiranje vodoničnih veza dobijenih elastomera proučavane su koristeći Furijeovu transmisionu infracrvenu spektroskopiju (FTIR). Uticaj udela tvrdih segmenata na morfologiju i svojstva povr&scaron;ine segmentiranih poliuretana, ispitivan je pomoću mikroskopije atomskih sila (AFM). Stepen kristalnosti uzoraka i dispergovanje nanočestica u dobijenim hibridnim materijalima su odre&ntilde;eni primenom metode rasipanja X-zraka pod &scaron;irokim uglom (WAXS).</p> / <p> In this work, poly(urethane-isocyanurate) elastomers, with covalent junction points,<br /> were synthesized by catalytic cyclotrimerization of telechelic diisocyanates as network<br /> presursors based on 2.4-tolylenediisocyanate, a,w,dihydroxypoly(oxypropylene) and monool<br /> component 2-(2-metoxyetoxy)ethanol. Thermoplastic polyurethanes, with physical<br /> crosslinking, were obtained by one-step technique and pre-polimerization method, using two<br /> aliphatic polycarbonate diols (differening in chain constitution), hexamethylene-diisocyanate<br /> and chain extender (1,4-butane diol) as reactive components. One serie of polyurethane<br /> hybrid materials was prepared by addition of 1 wt. % of organically modified clay<br /> nanoparticles (bentonite and montmorillonite). The goal of this work was to investigate the<br /> influence of elastically active and dangling chains content on thermal stability, dynamic<br /> mechanical and damping properties of polyurethane networks with heat-resistant<br /> isocyanurate-(hexahydro-1,3,5-triazin-2,4,6-trion) rings, as crosslinks. The aim was also to<br /> determine the influence of diisocyanate, macrodiol and chain extender reactive groups&rsquo; ratio<br /> and nanoparticles addition on surface properties, morphology, dynamic mechanical and<br /> thermal properties of obtained segmented unfilled and filled elastomers. Thermal degradation<br /> of poly(urethane-isocyanurate) networks and segmented thermoplastic polycarbonate-based<br /> polyurethanes was investigated by nonisothermal analysis, using thermogravimetry coupled<br /> with mass spectroscopy analysis (TG-MS) and thermogravimetry coupled with differential<br /> scanning calorimetry (TG-DSC). Viscoelastic and damping properties of obtained<br /> polyurethane elastomers were estimated by dynamic mechanical measurements (DMA).<br /> Modulated differential calorimetry (MDSC) was used to investigate thermal behavior of<br /> segmented polyurethanes and nanocomposites, synthesized using one-step technique. The<br /> glass transition temperature and thermoplastic properties of unfilled and filled polyurethane<br /> materials, prepared by pre-polimerization procedure were assessed by differential scanning<br /> calorimetry (DSC). Fourier transform infrared spectroscopy (FTIR) was used to investigate<br /> the hydrogen bond formation and chemical structure of prepared segmented elastomers. The<br /> investigation of the influence of hard segment content on morphology and surface topography<br /> of prepared segmented elastomers sheets was done by atomic force microscope (AFM). In<br /> order to determine the degree of cristallinity and to evaluate the dispersion of<br /> montmorillonite and bentonite in the polyurethane matrices, the prepared hybrid materials<br /> were characterized by wide angle X-ray scattering (WAXS).</p>