Дисертації з теми "Nanoparticle dispersions"
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Alele, Nkem [Verfasser], and Mathias [Akademischer Betreuer] Ulbricht. "Membrane-based purification of nanoparticle dispersions / Nkem Alele. Betreuer: Mathias Ulbricht." Duisburg, 2016. http://d-nb.info/1106854527/34.
Повний текст джерелаMilette, Jonathan. "Study of nanoparticle - liquid crystal dispersions using optical microscopy and solid-state NMR." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=106294.
Повний текст джерелаCette Thèse présente la synthèse d'une nouvelle famille de nanoparticules (NPs) d'or enrobées de cristaux liquides (CLs) afin de rationaliser leur miscibilité et assemblage dans des matrices faites de cristaux liquides. Un nouveau protocole basé sur la réaction d'échange de ligand thiol-pour-diméthylaminopyridine (DMAP) a été développé afin de préparer des NPs d'or de 4 à 5 nm de diamètre avec une monocouche simple et binaire faite d'alcanethiol (CH3(CH2)mSH; m = 5, 11) et du ligand CL 4'-(n-mercaptoalkoxy)biphényle-4-carbonitriles (CBO(CH2)nSH; n = 8, 12, 16). Nous avons découvert que les NPs d'or avec un ratio de 1:1 des ligands CH3(CH2)5SH/CBO(CH2)12SH possèdent une miscibilité sans précédent jusqu'à 25% en poids d'or dans la phase isotrope des CLs 4-n-pentyl-4'-cyanobiphényle (5CB) and 4-n-octyl-4'-cyanobiphényle (8CB). Bien qu'une faible concentration en NPs soit normallement utilisée afin d'éviter la formation d'agrégats, les dispersions concentrées de ces NPs d'or forment de nouvelles structures à la tansition de phase du CL par l'entremise du couplage des forces d'attraction interparticulaires avec les intéractions élastiques du CL. En refroidissant à TN-I, les NPs d'or forment de manière réversible un réseau à l'échelle microscopique en se concentrant à l'interphase nématique-isotrope. La topologie et l'orientation du domaine des directeurs CL sont controllées par la vitesse de refroidissement, l'alignement de surface, l'épaisseur du film, et la concentration et composition de la monocouche des NPs d'or. Des structures tout à fait différentes sont formées à la transition de phase nématique à smectique. Les NPs d'or dispersées dans des films de CLs alignés homotropiquement forment de manière réversible des domaines macroscopique de rayures parallèles courbées ou droites ayant une périodicité microscopique. Selon la variation des rayures en function des limites de surface, nous proposons que les NPs d'or se concentrent aux défauts des dislocations coin dans la phase smectique.Les intéractions moléculaires qui déterminent la miscibilité et l'assemblage des NPs d'or dans des CLs ont été étudiées avec l'aide la RMN multinucléaire à l'état solide, et de NPs d'or et CLs marqués isotopiquement. L'intéraction de la matrice CL avec la surface des NPs d'or se manisfeste de manière surprenante par l'alignement partielle des ligands. La détection d'une région biphasique isotrope-nématique de la matrice CL en-dessous de TN-I est une découverte importante qui va être utilisée afin de perfectionner les modèles thèoriques de la formation de réseaux. Finallement, un autre modèle de réseau fait de NPs, formé à partir de la dispersion d'aérosil dans un CL base de Shiff et ayant un moment dipolaire faible, a été étudié par la RMN du 2H. Nous avons examiné l'impact qu'a différentes forces d'ancrage de surface sur l'effet mémoire qu'affiche ces dispersions.
O'Brien, Kristen Wilson. "Synthesis of Functionalized Poly(dimethylsiloxane)s and the Preparation of Magnetite Nanoparticle Complexes and Dispersions." Diss., Virginia Tech, 2003. http://hdl.handle.net/10919/28869.
Повний текст джерелаPh. D.
Back, Markus. "Out-of-plane Ferromagnetic Resonance (FMR) measurements on magnetic nanoparticle dispersions for biomedical sensor applications." Thesis, Uppsala universitet, Fasta tillståndets fysik, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-410179.
Повний текст джерелаKosmala, A. "Development of high loading Ag nanoparticle inks for inkjet printing and Ag nanowire dispersions for conducting and transparent coatings." Thesis, Cranfield University, 2012. http://dspace.lib.cranfield.ac.uk/handle/1826/7754.
Повний текст джерелаEdwards, Bronwyn K. "Effect of combined nanoparticle and polymeric dispersions on critical heat flux, nucleate boiling heat transfer coefficient, and coating adhesion." Thesis, Massachusetts Institute of Technology, 2009. http://hdl.handle.net/1721.1/53288.
Повний текст джерелаCataloged from PDF version of thesis.
Includes bibliographical references (p. 123-126).
An experimental study was performed to determine thermal performance and adhesion effects of a combined nanoparticle and polymeric dispersion coating. The critical heat flux (CHF) values and nucleate boiling heat transfer coefficients (HTC) of nickel wires pre-coated using 1.0% alumina, 0.1% alumina, 500ppm polyallylamine hydrochloride (PAH), and 0.1% alumina combined with 500ppm PAH dispersions were determined using the pool-boiling method. The adhesion of 0.1% alumina and combined 0.1% alumina and 500ppm PAH coatings was evaluated using the tape and modified bend test methods. Results of the pool boiling experiments showed that the wire heaters pre-coated with combined 0.1% alumina and 500ppm PAH dispersion increase the CHF in water by -40% compared to bare wire heaters, compared to an enhancement of -37% with a 0.1% alumina coating. The combined 0.1% alumina and 500ppm PAH dispersion degrades the wire HTC by less than 1%, compared to a degradation of over 26% with a 0.1% alumina coating. Results from the tape test indicate qualitatively that the combined 0.1% alumina and 500ppm PAH dispersion coating adheres better than the 0.1% alumina nanoparticle coating. Results from the modified bend test showed that the combined 0.1% alumina and 500ppm PAH dispersion coating did not fail at the failure strain of the 0.1% alumina nanoparticle coating (8.108x 10-4). The addition of PAH to alumina nanofluid for creating a nanoparticle coating through boiling deposition was found to improve both coating thermal performance and adhesion over the pure alumina nanofluid.
by Bronwyn K. Edwards.
S.M.and S.B.
Gollamandala, Deepika Rao. "Brownian dynamic simulations of nanoparticle dispersions in polymer solutions a thesis presented to the faculty of the Graduate School, Tennessee Technological University /." Click to access online, 2009. http://proquest.umi.com/pqdweb?index=13&did=1913184241&SrchMode=1&sid=1&Fmt=6&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1265056184&clientId=28564.
Повний текст джерелаRhodes, Rhys William. "Controlling the morphology of nanoparticle-polymer composite films for potential use in solar cells." Thesis, University of Manchester, 2011. https://www.research.manchester.ac.uk/portal/en/theses/controlling-the-morphology-of-nanoparticlepolymer-composite-films-for-potential-use-in-solar-cells(6bc2a3cc-7c11-4615-a202-bead6360af99).html.
Повний текст джерелаQuant, Carlos Arturo. "Colloidal chemical potential in attractive nanoparticle-polymer mixtures: simulation and membrane osmometry." Thesis, Georgia Institute of Technology, 2004. http://hdl.handle.net/1853/7616.
Повний текст джерелаLe, Hong Duc. "Modelling of nanoparticles laden jet from a conveying pipe leakage." Phd thesis, Toulouse, INPT, 2018. http://oatao.univ-toulouse.fr/21454/1/LE_Hong_Duc.pdf.
Повний текст джерелаLopes, Filomeno Cleber. "Dispersions de nanoparticules magnétiques de type coeur-coquille MFe2O4@g-Fe2O3 dans des solvants polaires : réactivité électrochimique et rôle de l'interface oxyde/solution sur les propriétés colloïdales." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066673/document.
Повний текст джерелаDispersions of magnetic nanoparticles (NPs) in polar solvents have been inspiring many applications, to cite a few, biomedical, industrial and thermoelectrical ones. Also called ferrofluids (FFs), they are usually colloidal dispersions of magnetic spinel ferrite NPs, which can be stabilized thanks to electrostatic repulsion. A good understanding of the interface between NPs and the carrier solvent is thus a key point, which governs the interparticle interactions, the nanostructure and many other applicative properties. We study here the electrochemical reactivity of core-shell ferrite MFe2O4@ Fe2O3 (M=Fe,Co,Mn,Cu,Zn) NPs in aqueous medium. Square-wave voltammetry and potential controlled coulometry techniques are used on these non-conventional electroactive systems in order to evidence the shell of maghemite ( Fe2O3), the main function of which is to ensure the thermodynamical stability of NPs in acidic medium. We also present a new process for the elaboration of maghemite based FF in polar solvents, tested in water and applied to dimethyl sulfoxide (DMSO). Departing from the point of zero charge, the NPs are charged in a controlled way by adding acid or base, which enables us to better control the charge and the counter-ions nature, as well as the amount of free electrolyte in the dispersion. Stable dispersions are obtained thanks to electrostatic repulsion, also in DMSO. Small Angle X-ray scattering and Dynamic Light Scattering are used to understand the nanostructure and quantify the interparticle interactions. Specific ionic effects are evidenced as well as the strong influence of the solid/liquid interface on the migration of the NPs in a thermal gradient
Samuel, Jorice. "Synthèse et dispersion de nanoparticules luminescentes dédiées à la lutte anti-contrefaçon." Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10203.
Повний текст джерелаThis work deals with the synthesis and the dispersion of luminescent nanomaterials dedicated to the fight against counterfeiting. The nanomaterials (silica and rare earth oxides) own an optical code which is dispersed into the material to be tagged. The silica is synthesized by a reverse microemulsion sol-gel process. Organic fluorescent dyes and organo-lanthanides metal complexes are incorporated into the nanoparticles and it is shown that the nature of the dye influences its incorporation. The fluorescence is obtained without any covalent link between the dye and the silica matrix. After the synthesis, the nanoparticles are functionalized into the microemulsion. An original method is proposed to characterize the functionalization and it is shown that the functionalization is on the whole homogeneous but that at the nanoscale some nanodomains appear. The rare-earth oxides are obtained by collaboration. Two surface treatments are particularly studied : an hybrid approach based on the encapsulation of the nanoparticles into a polysiloxane shell followed by an adapted functionalization; and a second approach based on the use of surfactants. In particular, several well-known surfactants are compared. These modified nanoparticles are dispersed and stabilized into liquid media such as water or 2-Butanone. They are then incorporated into three polymers (PMMA, PVA and PVC) and it is shown that a good dispersion into a liquid allows obtaining an homogeneous incorporation into the polymers. An industrial test has been realized and has given the proof that some of these processes can be transferred directly at industrial scale
Dolce, Caterina. "Diffusion of polyelectrolytes in dispersions of nanoparticles." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066569/document.
Повний текст джерелаPolyelectrolytes are a particular class of polymers with ionizable repetition units that dissociate in polar solvents (such as water) leading to macro-ions and counterions. Solutions and materials made of polyelectrolytes are extensively used in several formulations and in industrial, biological and environmental processes. For a better insight into these systems, the properties of polyelectrolytes in presence of other particles have to be studied in more detail. This work deals with the modification of the dynamics properties of short polyelectrolytes in presence of charged silica nanoparticles.To study this problem, we design an experimental system made of carboxylate molecules of various sizes, from simple carboxylate (propionate) up to short polyelectrolytes (sodium polyacrylate, PAANa), diffusing in aqueous dispersions of silica nanoparticles of different size and surface charge. Both polyelectrolytes and nanoparticles are negatively charged at high pH. Thanks to the use of simple carboxylates, it is possible to reduce the complexity of the diffusers. The self-diffusion of the molecules is investigated using NMR diffusion experiments, which monitors the Brownian motions of individual molecules on 10-1000 ms timescale (10-100 μm spatial scale). This work also investigates how the presence of polyelectrolytes modifies the phase behaviour of silica particles by using small angle neutron scattering
Gerlach, Carina, Karsten Berndt, Olfa Kanoun, and Maik Berger. "CAD-unterstützte Bestimmung des effektiven Dispergiervolumens beim Ultraschalldispergieren." Universitätsbibliothek Chemnitz, 2016. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-206889.
Повний текст джерелаStarkweather, Nathan S. "Controlling Nanoparticle Dispersion For Nanoscopic Self-Assembly." DigitalCommons@CalPoly, 2012. https://digitalcommons.calpoly.edu/theses/973.
Повний текст джерелаSchmitt, Céline. "Surface modification of oxide nanoparticles using phosphonic acids : characterization, surface dynamics, and dispersion in sols and nanocomposites." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS083/document.
Повний текст джерелаColloidal nanoparticles (NPs) dispersions are largely used in the industry, and avoid the use of dried NPs, which is controversial due to safety concerns. The key point in such systems remains the control of the interactions with the dispersed medium and between the NPs. Mastering these interactions allows controlling the NPs' state of dispersion. Moreover, as polymer-NPs nanocomposites have been found promising for a wide variety of applications, the use of colloidal sols could thus be an advantageous way of NPs' incorporation in the polymer, with a possible control of the NPs state of dispersion, and finally on the properties of the material, as they are linked to the NPs' dispersion. The purpose of this PhD work is to develop surface-functionalization methods of oxide NPs in colloidal sols in order to control the dispersion of NPs in the sols and in polymer nanocomposites derived from these sols, and to evaluate this dispersion using SAXS. Two surface modification methods have been developed to obtain aqueous or organic sols of functionalized NPs. The first one concerns the reaction in water of alumina-coated silica NPs with phosphonic acids (PAs), and the second one involves the simultaneous grafting and phase transfer of TiO2 NPs from an aqueous to a CHCl3 phase using PAs. The resulting NPs were characterized and their state of dispersion was monitored by DLS and SAS measurements. The impact of the C8PA grafting density on the structure of modified alumina-coated silica NPs in the dried state was evidenced by SAXS. The different relaxation processes of bare and grafted NPs were studied by BDS. These NPs were then incorporated in a PEA polymer by an aqueous latex route, and their structure in the nanocomposites was investigated by SANS
BELENO, LUIS MIGUEL GUTIERREZ. "HYBRID SILICA NANOPARTICLES FOR STABILIZATION OF BIPHASIC DISPERSIONS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2017. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=37041@1.
Повний текст джерелаCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
As dispersões bifásicas (ex. espumas e emulsões), de grande relevância prática na química e na engenharia, são termodinamicamente instáveis devido à diminuição de energia livre no processo de coalescência. Esta limitação é comumente minimizada através de mecanismos de estabilização eletrostática e estérica. Recentemente, há um interesse crescente na estabilização de emulsões e espumas usando partículas sólidas (tipo Pickering), devido à forte adsorção das mesmas nas interfaces para formar uma película sólida. Dependendo do tamanho e do ângulo de contato, a adsorção das partículas pode tornar-se irreversível, melhorando a estabilidade em comparação com sistemas estabilizados por surfactante. Como nanopartículas de molhabilidade intermédia são relativamente raras, o ajuste deste parâmetro é o principal desafio para obter dispersões estáveis. No presente estudo, nanopartículas de sílica (SiNPs) foram modificadas superficialmente com 3-aminopropil trimetoxisilano e hexadeciltrimetoxisilano como agentes sililantes, para se obter três tipos diferentes de nanopartículas híbridas de maior hidrofobicidade, visando a formulação de dispersões bifásicas altamente estáveis usando um método de baixa energia (agitação manual). As SiNPs modificadas foram caracterizadas através de testes qualitativos, infravermelho, analise termogravimétrica, analise elementar e ressonância magnética nuclear de carbono treze e de silício vinte nove no estado sólido para confirmar o enxerto dos grupos funcionais. As propriedades das NPs em relação à sua dispersabilidade e comportamento em interfaces foram avaliadas por espalhamento de luz dinâmica e a tensão superficial crítica de molhabilidade. Finalmente, foram preparadas espumas líquidas e emulsões água-em-óleo (A/O) utilizando as partículas híbridas obtidas e pequenas quantidades de surfactantes, para facilitar o processo de dispersão. Os resultados mostraram que as NPs mais hidrofílicas estabilizam melhor a interface ar/água (espumas), enquanto a estabilização máxima em emulsões é obtida com as NPs mais hidrofóbicas, uma vez que a interação com a fase contínua é otimizada. Além disso, a presença de grupos funcionais na superfície das SiNPs oferece a possibilidade de obter efeitos de sinergia com os surfactantes, controlando a adsorção mista na interface. As aplicações potenciais destes resultados podem abranger diversas áreas, tais como biomedicina, ciência dos materiais, recuperação de petróleo, cosméticos e alimentos.
Biphasic dispersions (e.g. foams and emulsions) are of practical relevance to many chemical and engineering fields. These dispersions are thermodynamically unstable, since their decay results in a decrease of the free energy. Different mechanisms can prevent the coalescence of the dispersion, such as electrostatic and steric stabilization. Recently, there has been an increased interest in the study of stabilization of emulsions and foams using solid particles (Pickering type), since particles can strongly adsorb at interfaces to form a solid film, replacing the incompatible water-oil(ar) interface by the more favorable oil(ar)-particle and particlewater interfaces. Depending on their size and contact angle of selective wetting, particle adsorption can become irreversible, with increased stability of particle-stabilized dispersions compared to surfactant-stabilized systems. Since particles of intermediate wettability by nature are relatively rare, tailoring particle wettability is the major challenge to obtain stable dispersions. In the present study, hybrid silica nanoparticles (SiNPs) were prepared by modification of their surface using 3 aminopropyltrimethoxysilane and hexadecyltrimethoxysilane as silanizing agents, to obtain three different nanoparticles with increased hydrophobicity, aiming to achieve highly stable biphasic dispersions using a low-energy method. The modified SiNPs were characterized using qualitative tests, FTIR, TGA, CHN and NMR (Si) to confirm grafting of functional groups. In addition, nanoparticle properties regarding aqueous dispersions and behavior at interfaces were evaluated by DLS and critical wetting surface tension. Liquid foams and water-in-oil (W/O) emulsions were prepared using the obtained hybrid particles and small amounts of different surfactants, to facilitate the dispersion process. The results showed that while more hydrophilic NPs stabilize better the air/water interface (foams), maximum stabilization in W/O emulsions is achieved with the most hydrophobic NPs, since interaction with continuous phase is optimized. In addition, the presence of different functional groups at the surface of the SiNPs offers the possibility for increased synergy with surfactants, controlling the mixed adsorption at the interface. The potential applications of these results can cover diverse fields such as biomedicine, materials science, oil recovery, cosmetics and food.
Kastrisianki-Guyton, Emma. "Dispersion, adsorption properties and separation of nanoparticles." Thesis, University of Bristol, 2015. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.683906.
Повний текст джерелаMeeuw, Hauke, Valea Kim Wisniewski, U. Köpke, Ali Shaygan Nia, Vázquez Adrián Romaní, Martin Rudolf Lohe, Xinliang Feng, and Bodo Fiedler. "In‑line monitoring of carbon nanoparticle epoxy dispersion processes." Springer, 2019. https://tud.qucosa.de/id/qucosa%3A70656.
Повний текст джерелаKylafis, Georgios Fokion. "The explosion and dispersion potential of engineered nanoparticles." Thesis, University of Leeds, 2016. http://etheses.whiterose.ac.uk/15618/.
Повний текст джерелаZhang, Li. "FDTD Algorithm for Plasmonic Nanoparticles with Spatial Dispersion." The Ohio State University, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=osu1452174003.
Повний текст джерелаPourcin, Florent. "Synthèse de nanoparticules de forme, taille et dispersion contrôlées pour l'élaboration de couches composites aux propriétés optiques modulables." Thesis, Aix-Marseille, 2018. http://www.theses.fr/2018AIXM0365/document.
Повний текст джерелаNanoparticles of noble metals have unexpected optical properties. Under the effect of light, they are able to resonate, generating localized surface plasmon resonances that are used in many applications. These plasmons absorb and scatter the light at the wavelengths of these resonances and are highly dependent on the shape, the size and the environment of the nanoparticles. In this thesis, they are applied for the design of stealth materials for military purposes. For this, controlled shapes of silver nanoparticles were blended within a polymer to develop new hybrid materials that are solution-processed as thin layers. A quasi-perfect absorber (98,8%) in a precise range of wavelengths has been obtained by maintaining well-dispersed nanoparticles in the layer, while an effective broadband absorber (~90%) over the entire visible range has been achieved by triggering the aggregation of the nanoparticles. Microscopy and spectroscopy qualitative studies performed on the density and organization of the nanoparticles within the thin layers revealed the presence of plasmonic couplings of different natures and intensities as a function of the spacing between the cubes. It has been shown that the optical properties measured are independent of the nature of the substrates used and independent of the angle of the incident light on a wide angular range. Finally, solution-processing of multilayers systems was explored to extend the absorption of the layers to the near infrared by the addition of other materials such as tungsten oxide
Yourdkhani, Mostafa. "Aspects of nanoparticles dispersion and interaction in polymer nanocomposites." Thesis, McGill University, 2014. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=123090.
Повний текст джерелаLes polymères nano-renforcés ont attiré beaucoup d'attention au cours des dernières décennies. Profitant de la géométrie à l'échelle nanométrique, immense rapport surface/volume, et les propriétés chimiques et physiques exceptionnelles, les nanoparticules améliorent en théorie la performance des systèmes de polymères. Dans la pratique, la préparation de polymères nano-renforcés comporte ses propres défis. Pour obtenir le meilleur renforcement possible, les nanoparticules doivent être uniformément dispersées dans la matrice, afin d'interagir efficacement avec les chaînes du polymère. Les forces d'attraction moléculaires qui existent à l'interface entre différentes nanoparticules rendent ces problèmes difficiles à surmonter. En outre, la présence de nanoparticules dans la matrice modifie de manière significative les procédés de fabrication de ce système polymère. Par conséquent, l'objectif principal de cette thèse est d'étudier la dispersion et les interactions interfaciales dans les polymères nano-renforcés. Pour éviter les incertitudes liées à l'analyse visuelle et qualitative de la dispersion, utilisée couramment par les chercheurs, un algorithme robuste a été développé pour quantifier automatiquement l'état de dispersion dans les micrographies optiques et électroniques. Plusieurs expériences ont été réalisées pour comprendre l'influence de la modification de surface des nanoparticules sur la performance des polymères nano-renforcés. Deux matériaux différents ont été examinés: un polylactide (PLA) renforcé avec des organo-argiles, et un époxy renforcé par des nanotubes de carbone (CNT). Il a été démontré qu'une modification appropriée de la surface des nanoparticules pourrait faciliter la dispersion, et par conséquent pourrait améliorer les performances mécaniques et physiques du matériau. Pour comprendre l'effet des procédés de fabrication sur la dispersion des polymères nano-renforcés, une étude systématique sur la stabilité de la dispersion de résine époxyde renforcée par des CNT a été effectuée. Il a été constaté que, à des températures élevées, les nanotubes de carbone présentent peu d'affinité avec la résine, et de ce fait, tous les facteurs qui favorisent la possibilité de contacts entre nanotubes peuvent conduire à leur ré-agglomération. Par conséquent, pendant le procédé de fabrication, la stabilité de la dispersion est fortement influencée par la mobilité induite par l'écoulement de nanotubes résultant de forces de cisaillement externes ou un changement de la viscosité. Les connaissances acquises tout au long de cette enquête peuvent être utilisés pour optimiser les procédés et les méthodes de fabrication afin de maintenir une dispersion stable tout au long de la fabrication, et obtenir ainsi un polymère nano-renforcé avec des performances accrues.
Kern, Barreto Cynara Caroline. "Dispersão de nanopartículas magnéticas em meios complexos biodegradáveis." Thesis, Paris 6, 2016. http://www.theses.fr/2016PA066419/document.
Повний текст джерелаMagnetic nanocolloids are dispersions of magnetic nanostructures in a carrier fluid. Thanks to the original properties of both the liquid and the magnetic particles, these dispersions can be confined, moved, deformed and controlled by applying an external magnetic field. Such dispersions thus have many applications in nanoscience and nanotechnologies.We studied the dispersion of magnetic nanoparticles in deep eutectic solvents (DES). These solvents (DES), obtained by mixing a quaternary ammonium salt (e.g., choline chloride Ch) and a hydrogen bond donor (e.g., ethyleneglycol EG or Urea U) have properties similar to ionic liquids, and are also biodegradable. One of the questions about these dispersions is the nature of the forces implied in colloidal stability, since the DLVO model classically used in water cannot be invoked here due to the very high ionic strength of the solvent.In a first step, we have carefully characterized two DES ((ChEG (1:3) and ChU (1:2) in mol), measuring the density and viscosity for temperatures between 20 and 45°C. We could thus show the high association in these liquids.A protocol to disperse nanoparticles of maghemite (Fe2O3) or mixed ferrite (CoxZn1-xFe2O4) is then proposed, and the obtained dispersions are studied by dynamic light scattering and SAXS. The size polydispersity was reduced by size sorting, and it reveals that the smallest particles are the most easy to disperse in the DES.Last, a synthesis of NMP in clay dispersion was tested and showed promising results with a reduced size polydispersity
Crane, Nathan B. 1974. "Strengthening porous metal skeletons by metal deposition from a nanoparticle dispersion." Thesis, Massachusetts Institute of Technology, 2005. http://hdl.handle.net/1721.1/32385.
Повний текст джерелаIncludes bibliographical references.
The accuracy of solid freeform fabrication processes such as three-dimensional printing (3DP) and selective laser sintering (SLS) must be improved for them to achieve wide application in direct production of metal parts. This work seeks to reduce sintering and deformation of porous metal skeletons during liquid-metal infiltration by reinforcing the skeletons with metal deposits. This can be accomplished by depositing a metal from a suspension of nanometer-scale iron particles. The nanoparticle deposits from the suspension concentrate in regions of high stress when the solvent is removed by drying. The particles are sintered to create a dense structure that reinforces the porous skeleton-reducing deformation and creep. Generically, this work studies a process for metal deposition from a liquid carrier with unique transport characteristics compared to traditional metal deposition processes such as plating, chemical vapor deposition, evaporation, and sputtering. This process of depositing metal from nanoparticle suspensions is studied using a commercial product of iron nanoparticles. The processed iron particle suspension contains significant carbon from the organic dispersants used to stabilize the suspension. Gas adsorption, X- ray diffraction, and SEM imaging were used to show that the carbon aids reduction of any iron oxide on heating and strongly influences the densification characteristics. The iron nanoparticles are applied to porous steel skeletons produced by sintering stainless steel powder. These are then heated to typical steel infiltration temperatures of 1284 C. The nanoparticle deposits are shown to reduce creep deflections at infiltration temperatures by up to 95% and reduce shrinkage by up to 60%.
(cont.) The best results are obtained by repeating the process of applying the nanoparticles, drying the solvent, and sintering them to 700 C up to four times. The performance in magnetic materials can also enhanced by applying a magnetic field along the magnetic particles. This magnetic field concentrates the nanoparticle deposits into the contact points between the skeleton particles where they provide optimal benefit.
by Nathan Brad Crane.
Ph.D.
Spence, D'Anne Emmett. "Intercalated MoS2 nanoparticles for enhanced dispersion in smokes and obscurants." College Park, Md. : University of Maryland, 2003. http://hdl.handle.net/1903/56.
Повний текст джерелаThesis research directed by: Dept. of Chemistry and Biochemistry. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
Cao, Xue-Zheng, Holger Merlitz, Chen-Xu Wu, Goran Ungar, and Jens-Uwe Sommer. "A theoretical study of dispersion-to-aggregation of nanoparticles in adsorbing polymers using molecular dynamics simulations." Royal Society of Chemistry, 2016. https://tud.qucosa.de/id/qucosa%3A36333.
Повний текст джерелаCosta, Elisabete Fernandez Reia Da. "Liquid moulding of carbon nanoparticle filled composites." Thesis, Cranfield University, 2011. http://dspace.lib.cranfield.ac.uk/handle/1826/7276.
Повний текст джерелаCruceanu, Florentin I. "AC-calorimetry and dielectric spectroscopy on anisotropic liquid crystal and aerosil dispersions." Worcester, Mass. : Worcester Polytechnic Institute, 2008. http://www.wpi.edu/Pubs/ETD/Available/etd-040908-143149/.
Повний текст джерелаKeywords: phase transitions; quenched random disorder; liquid crystals; dielectric spectroscopy; calorimetry. Includes bibliographical references (leaves 78-83).
Truong, Bao H. (Bao Hoai). "Critical heat flux enhancement via surface modification using colloidal dispersions of nanoparticles (Nanofluids)." Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/44775.
Повний текст джерелаIncludes bibliographical references (leaves 97-103).
Nanofluids are engineered colloidal dispersions of nanoparticles (1-100nm) in common fluids (water, refrigerants, or ethanol...). Materials used for nanoparticles include chemically stable metals (e.g., gold, silver, copper), metal oxides (e.g., alumina, zirconia, silica, titania) and carbon in various forms (e.g., diamond, graphite, carbon nanotubes). The attractive properties of nanofluids include higher thermal conductivity, heat transfer coefficients (HTC) and boiling critical heat flux (CHF) than that of the respective base fluid. Nanofluids have been found to exhibit a very significant enhancement up to 200% of the boiling CHF at low nanoparticle concentrations. In this study, nanofluids were investigated as an agent to modify a heater surface to enhance Critical Heat Flux (CHF). First, the CHF of diamond, Zinc Oxide and Alumina water-based nanofluids at low volume concentration (<1 vol%) were measured to determine if nanofluid enhances CHF as seen in literature. Subsequently, the heaters are coated with nanoparticles via nucleate boiling of nanofluids. The CHF of water was measured using these nanoparticle precoated heaters to determine the magnitude of the CHF enhancement. Characterization of the heaters after CHF experiments using SEM, confocal, and contact angle were conducted to explain possible mechanisms for the observed enhancement. The coating thickness of the nanoparticle deposition on a wire heater as a function of boiling time was also investigated. Finally, theoretical analyses of the maximum CHF and HTC enhancement in term of wettability were performed and compared with the experimental data. The CHF of nanofluids was as much as 85% higher than that of water, while the nanoparticle pre-coated surfaces yielded up to 35% CHF enhancement compared to bare heaters.
(cont.) Surface characterization of the heaters after CHF experiments showed a change in morphology due to the nanoparticles deposition. The coating thickness of nanoparticle was found to deposit rather quickly on the wire surface. Within five minutes of boiling, the coating thickness of more than 1 pm was achieved. Existing CHF correlations overestimated the experimental data.
by Bao H. Truong.
S.M.
Picard-Lafond, Audrey. "Synthèse de nanoparticules riches en carbone par polymérisation en dispersion." Master's thesis, Université Laval, 2017. http://hdl.handle.net/20.500.11794/27902.
Повний текст джерелаThe interest in carbon nanomaterials is expanding due to their potential for various applications. The network of sp²-hybridized carbon atoms, common to all materials of this family, generates excellent electronic and optical properties which are modulated by the shape, the size and the dimensionality of the carbon network. Among these nanomaterials, carbon nanoparticles (CNP) have a singular potential due to their photoluminescence properties, their photostability and their low toxicity. Accordingly, the application of CNP in biomedicine, optoelectronics and photocatalysis is greatly studied. However, the current synthetic methods and separation techniques represent limitations to their implementation. The use of high temperatures (>100 °C) hinders the precise control over shape and size of the CNP, the synthetic yields are low and the materials’ surface is chemically inert. In this project, the objective is to establish a route for CNP synthesis which surpasses the limitations of the current preparation methods. In other words, we are trying to develop a method allowing a precise control of the particles’ shape and size, while avoiding the use of high temperatures. The strategy is based on the dispersion polymerization of alkyne-rich organic units, used as a metastable carbon source. On one hand, the polymerization of alkyne-rich monomers allows the one-step synthesis of polyynes which, due to their instability, react spontaneously to produce a material composed mainly of sp²-hybridized carbon atoms. On the other hand, dispersion polymerization ensures a morphological control of the particles during their synthesis. Adding to the main objective, surface functionalization of the particles is intended by exploiting the reactivity of residual alkynes in the carbon structure. Also, we try to exchange the alkyne-rich monomer in order to improve the photoluminescence properties of the particles obtained from the developed process.
Cabreira, Gomes Rafael. "Dispersions de nanoparticules magnétiques de structure coeur/coquille : propriétés magnétiques et thermodiffusion." Thesis, Paris 6, 2014. http://www.theses.fr/2014PA066568/document.
Повний текст джерелаOur objective is to understand how the magnetic properties of nanoparticles (NPs) can be affected by their size reduction and their chemical composition, and also to determine their role on their thermophoretic motion and on the magneto-caloric effect. For this purpose, aqueous ferrofluids are synthesized with core-shell NPs based on a core of Mn-ferrite, Co-ferrite and mixed Zn-Mn ferrites, coated with a maghemite shell. The magnetic measurements evidence a ferrimagnetic core, covered with disordered frozen spins (SGL), driving an exchange bias phenomenon shifting the hysteresis loops, when the system is cooled under a field Hfc. This exchange bias is measured as a function of Hfc, in samples with NPs having either a hard (CoFe2O4) or a soft (MnFe2O4) magnetic core. Whatever the nature of the magnetic core, the exchange bias field grows up to reach a maximum, always found at Hfc of the order of half of the anisotropy field. The thermophoretic properties of the dispersions, probed by Forced Rayleigh Scattering, are ruled by colloidal physico-chemical features (surface ligand, counter ions, interparticle interactions) whatever the chemical composition and the magnetic properties in zero magnetic field. The Soret coefficient is found here negative (thermophilic NPs) and is related to the osmotic compressibility, modeled by an effective Carnahan-Staring formalism. In the dilute regime, the friction follows an Einstein law, while a Vogel-Fulcher formalism describes the concentrated regime, at the approach of the glass transition. The magneto-caloric measurements demonstrate a similarity with commercial materials. They are strongly influenced by the core composition
Farrugia, Brooke Louise Graduate School of Biomedical Engineering Faculty of Engineering UNSW. "Analysis of nanoparticle dispersion, biological interactions and drug incorporation of polyurethane nanocomposite materials." Awarded By:University of New South Wales. Graduate School of Biomedical Engineering, 2010. http://handle.unsw.edu.au/1959.4/44826.
Повний текст джерелаVoormann, Hauke [Verfasser]. "Smart dispersion of carbon nanoparticle epoxy composites: from nano to application / Hauke Voormann." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2021. http://d-nb.info/123281296X/34.
Повний текст джерелаRagheb, Ragy. "Synthesis and Characterization of Polylactide-siloxane Block Copolymers as Magnetite Nanoparticle Dispersion Stabilizers." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/31687.
Повний текст джерела
The synthesis of the triblock copolymers is comprised of three reactions. Difunctional, controlled molecular weight polymethylvinylsiloxane oligomers with either aminopropyl or hydroxybutyl endgroups were prepared in ring-opening redistribution reactions. These oligomers were utilized as macroinitiators for ring-opening L-lactide to provide triblock materials with polymethylvinylsiloxane central blocks and poly(L-lactide) endblocks. The molecular weights of the poly(L-lactide) endblocks were controlled by the mass of L-lactide relative to the moles of macroinitiator. The vinyl groups on the polysiloxane center block were further functionalized with carboxylic acid groups by adding mercaptoacetic acid across the pendent double bonds in an ene-thiol free radical reaction. The carboxylic acid functional siloxane central block was designed to bind to the surfaces of magnetite nanoparticles, while the poly(L-lactide)s served as tailblocks to provide dispersion stabilization in solvents for the poly(L-lactide). The copolymers were complexed with magnetite nanoparticles by electrostatic adsorption of the carboxylates onto the iron oxide surfaces and these complexes were dispersible in dichloromethane. The poly(L-lactide) tailblocks extended into the dichloromethane and provided steric repulsion between the magnetite-polymer complexes.
Master of Science
Lin, Yaochen. "Dispersion de nanoparticules ferroélectriques dans un cristal liquide : élaboration, transitions de phases et propriétés diélectriques." Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0443/document.
Повний текст джерелаLiquid crystals are organic materials used to make electronic devices ; before using this material in applications, it is necessary to study their physical-chemical and dielectric properties in order to optimize their performance. This study is devoted to the nanocolloids obtained by dispersing ferroelectric nanoparticles in a nematic liquid crystal ; it means an inclusion influences the phase transitions temperatures and the dielectric properties of the host. The phase transitions measured by using Differential scanning calorimetry (DSC) evidenced the ferroelectric nanoparticles influence ; which is attributed two effects : the nanoparticles spontaneous polarization and the anchoring effect between nanoparticles and liquid crystal. The dielectric characterisation revealed the coupling between the macroscopic polarization of the inclusions and the electric field ; this coupling is manafested by an increase of phase transition temperatures compared to those determined by DSC. The competition between the polarization effect under an electric field and the anchoring effect induces a modification of the permittivities (parallel and perpendicular) and the dielectric anisotropy. Using harvested nanoparticles, the study confirmed the importance of the nanoparticles polarization to increase the properties of the studied nanocolloids. In fact, very small quantity of the harvested nanoparticles presents more significant improvements than those obtained with the non-harvested nanoparticles
Ganapathy, Subramanian Santhana Gopinath. "A continuous impingement mixing process for effective dispersion of nanoparticles in polymers." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4320.
Повний текст джерелаKumar, Prashant. "Measurements and modelling of the dispersion of nanoparticles in the urban environment." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611184.
Повний текст джерелаParrenin, Laurie. "Synthèse et formulation d'encres polymères pour couche active de cellules solaires organiques." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0183/document.
Повний текст джерелаThe replacement of halogenated toxic solvents is fundamental in photoactive material processes to make the organic photovoltaic sector viable. Herein the use of nanoparticles made of π-conjugated polymer (PCDTBT) and electron-acceptor(PC71BM) was targeted in order to allow for instance the control of the phase separation between the two materials. Thus composite particles of PCDTBT and PC71BM have been synthesized using two kinds of stabilizers: an anionic surfactant (SDS) and a block copolymer P3HT-b-PEO, as well as without stabilizer. As an example such nanoparticles were integrated as active layer into photovoltaic device enabling a power conversion efficiency of 0.94% from aqueous based inks
Kossi, Alaedine. "Consolidation de dispersions colloïdales d'oxyde de titane sous compression osmotique." Nice, 2012. http://www.theses.fr/2012NICE4115.
Повний текст джерелаSegovia, Mera Alejandro. "Effets de la dispersion de nanoparticules dans un cristal liquide ferroélectrique sur les propriétés ferroélectriques et de relaxations diélectriques." Thesis, Littoral, 2017. http://www.theses.fr/2017DUNK0461/document.
Повний текст джерелаThe present thesis work concerns materials made of dispersions of nanometric colloidal particles, from a bulk ferroelectric material, dispersed within a chiral smectic phase of a ferroelectric liquid crystal. The goal of this work is to study the effect of the dispersed nanoparticles over the nanocolloïd properties, specially the ones related to ferroelectricity. This study showed no change over mesomorphic and ferroelectric behavior of the materials. A decrease in spontaneous polarization and phase transition temperatures was found for low nanoparticle concentrations. A "transition" of these behaviors was observed for a critical concentration, beyond which, nanoparticles aggregate and form clusters inside the liquid crystal matrix. Afterwards, we have studied two dielectric relaxation modes. The first one related to distorsions of the helix in the ferroelectric phase and the second one to the compression movements of the smectic layers around the ferroelectric-paralectric transition. The observed behaviors seem to be due to modifications of the visco-elastic properties of nanocolloids, produced by intercalation of nanoparticles between the smectic layers
Daoura, Oscar. "Towards anti-coking and anti-sintering Ni@Silica based catalysts for the dry reforming of methane." Electronic Thesis or Diss., Sorbonne université, 2019. http://www.theses.fr/2019SORUS679.
Повний текст джерелаDry reforming of methane is a process for the conversion of CH4 and CO2 into “syngas”, a gaseous mixture of H2 and CO (with a molar ratio value of 1) that can serve as feedstock for the production of liquid fuel by the mean of Fischer-Tropsch procedure. Nickel-based catalysts are promising candidates for this reaction displaying high activity, lower cost and wider availability than noble metal-based materials but deactivating by sintering and/or coke deposition. Stabilization of Ni0 nanoparticles within siliceous supports either by confinement and/or by improving their dispersion and interaction with the support are among the best and the less expensive methods to overcome the deactivation in dry reforming which represents the main objective for this work. Here, new stable nickel-based catalysts were synthesized, characterized and tested in dry reforming. Three main issues were examined: (i) Testing the efficiency of new mesoporous supports (mesocellular silica foams) using different nickel precursors (salt or colloidal form) incorporated by impregnations or pH adjustment assisted one-pot methods, (ii) designing highly dispersed nickel-based mesoporous monoliths through an original sol-gel method (iii) controlling the nickel size, dispersion and therefore its interaction with the support onto non-porous silica carriers by the mean of phyllosilicates. Monoliths of the SBA-15 type incorporating Ni0 by a one-pot method, and Ni0 obtained through the reduction of nickel phyllosilicates turned out to be the most stable and efficient catalysts
Bonnefond, Sylvain. "Amplification de la fluorescence par diffusion multiple : une étude exploratoire vers des conditions biocompatibles." Thesis, Université Côte d'Azur (ComUE), 2019. http://www.theses.fr/2019AZUR4080.
Повний текст джерелаThe purpose of this PhD has been to develop a method of amplification of the fluorescence by using the multiple scattering (introduction of dielectric, elastic and passive nanoparticles) that will be applicable to biological samples. This required doing the link between the biological laser and random laser concept for a use in an amplified regime, which precedes the laser regime, applicable to cell and tissue labelling. The generation of an amplification passes by the use of scatterers (nanoparticles of titanium dioxide in this work) homogeneously distributed. It required developing conditions of the colloidal stabilization to avoid the aggregation of nanoparticles into biological media and buffers by the adsorption of proteins (BSA). An optical setup has been developed to excite the fluorescence, by accurately evaluating the pump energy and the pulse response of fluorescence, while optimizing the observation window to limit photobleaching of fluorophores and cell toxicity. A first stimulated amplification was shown and validated with a colloidal suspension in a homogeneous aqueous solution of FITC at a concentration of 200 µM. This experiment has shown that it is possible to achieve a fluorescence gain up to 40 associated with a decrease in spectral width up to 5 nm, and an overall reduction in lifetime. The presence of the stimulated emission process in amplification is confirmed by the correlation between fluorescence and nanoparticle concentration or pump energy. This first step was extended to concentrations of 2 and 20 µM for which a rapid saturation of the gain (respectively ~ 10 and 20) was observed. Finally, amplification has been shown and validated on CFSE-labeled or GFP-expressing suspension cells in their culture medium. In these conditions, a decreasing of the gain compared with the previous conditions has been observed (up to 6 – 10 times). The explanation of this lower gain has been explored by testing the changes of media on amplification, and the presence of a layer of BSA surrounding the nanoparticles seems to be the cause because the protein decreases probably the refractive index of the nanoparticle leading a weak scattering
Baranauskas, Victor Vincent. "Cobalt Nanoparticle-Macromolecular Complexes and Their Conversion to Oxidatively Stable Entities." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/27376.
Повний текст джерелаPh. D.
Schneider, Wolfgang Benedikt. "Quantenchemie in elektrochemischen Prozessen." Doctoral thesis, Universitätsbibliothek Chemnitz, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:ch1-qucosa-169966.
Повний текст джерелаIranzo, Audrey. "Electrosynthèse assistée par ultrasons de nanoparticules de fer à valence zéro : étude de la croissance de dépôts et de leur dispersion par ondes acoustiques." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30317/document.
Повний текст джерелаThis study concerns the coupling of the ultrasounds with the electrodeposition process for the synthesis of zero-valent iron nanoparticles; it is structured in two sections. The first focuses on the electrode substrate used for the iron electrodeposition and aims to determine its influence on both the deposit growth and its dispersion by ultrasonication. The interfacial and the adhesion energies of the deposit on the substrate (Y_(Fe/substrate) and W_(Fe/substrate) respectively) being related to the surface energy and the roughness of the substrate, a particular focus is put on the influence of these two properties. Thus, two materials of different surface energies, gold (Au) and vitreous carbon (VC), as well as various roughnesses, are tested. Considering only the Van der Waals interactions, a theoretical development has enabled to determine that Y_(Fe/VC)>Y_(Fe/Au) which suggests a better affinity of the iron deposit with the gold than with the VC substrate. This difference impacts the deposit morphology (2D growth on the gold and 3D growth on the VC substrate) but also the deposit adhesion. Indeed, experiments performed to study the effect of ultrasounds on the iron electrodeposit reveal its progressive and complete dispersion for the vitreous carbon case while no dispersion (no removal of the deposit from the electrode) is obtained with the gold substrate. The second section of the present study deals with the synthesis of iron nanoparticles; to this end, the electrodeposition of branched deposits has been investigated in a Hele-Shaw cell integrating a vibrating element (piezoelectric diaphragm), expected to allow both the deposit formation and its fragmentation. Experiments reveal that the hydrogen bubbles, formed by the co-reduction of free protons during the iron electrodeposition, strongly influence the fragmentation process. Using high vibration frequencies and high amplitudes, the bubbles oscillate with surface deformations, inducing interface velocity sufficiently high (˜ 4 m/s) to allow the fragmentation of the deposit into particles of sizes ranging between 1 µm and 100 nm and showing a high specific surface due to their dendritic morphology. Thus this work opens the way for a new particles manufacturing technology
Gers, Romain. "Analyse locale de l'hydrodynamique d'un broyeur à billes agité pour le traitement de dispersions solide-liquide." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT024H/document.
Повний текст джерелаThe stirred media mill is used to produce nanoparticles from dense suspensions. The purpose of our study is to analyse the influence of the hydrodynamics on the fragmentation process. The first part is devoted to the flow modelling in the mill for an equivalent fluid. The constitutive law is accounting for the properties of grinding beads and suspended particles. Velocity fields, obtained by direct numerical simulations, have permitted to analyse the collision characteristics and to determine the major mechanisms leading to fragmentation. By determining the impact velocities and collisional Reynolds we were able to set up an experiment modelling two approaching grinding beads. One bead is mobile while the other is fixed. The flow velocities in the fluid have been measured by PIV for a wide range of conditions. These velocity fields have been used to calculate particle trajectories within the gap between the two beads. This yields to estimate a capture efficiency for particles. We concluded that an increase of the particle diameter or an increase of the impact velocity increases the probability of capture. Additionally, trajectories of deposited particle at the surface of the fixed spheres show that the capture efficiency decreases when the Stokes number of the particle increases
Thompson, Michael Shane. "Enabling Synthesis Toward the Production of Biocompatible Magnetic Nanoparticles With Tailored Surface Properties." Diss., Virginia Tech, 2007. http://hdl.handle.net/10919/28395.
Повний текст джерелаPh. D.
Bonnevide, Marine. "Nanocomposites élastomère-nanoparticules de silice greffées : de la synthèse aux mécanismes de dispersion." Electronic Thesis or Diss., Aix-Marseille, 2019. http://www.theses.fr/2019AIXM0354.
Повний текст джерелаThe addition of nanometric fillers into a polymer matrix significantly improves its use properties. Optimization of nanocomposite reinforcement is related to the filler dispersion state in the matrix as well as to the filler/filler and filler/matrix interactions. In the tire industry, numerous studies have been devoted to these parameters in order to understand and control the reinforcement of elastomeric matrices such as Styrene Butadiene Rubber by silica nanoparticles. On an industrial scale, functional polymer or coupling agents such as bis(triethoxysilyl)propyl tetrasulfide are used to improve the dispersion of silica particles in elastomers and strengthen the matrix. However, it is difficult to control the grafting density and to modulate some parameters that may influence the dispersion state and interactions e.g. the nature and molar mass of the polymer chains covalently attached to the surface. To address these limitations, in this project we propose to synthesize silica nanoparticles grafted with polyisoprene, polybutadiene and statistical poly(butadiene-co-styrene) chains using the “grafting from” method associated to nitroxide mediated polymerization. In this aim, an alkoxyamine is grafted onto the nanoparticle surface in two steps by keeping the colloidal stability of the particles. After optimizing grafting parameters and polymerize the different monomers, the obtained grafted nanoparticles are characterized in terms of molar mass, microstructure, grafting density and gyration radius of the grafted chains. Their dispersion state is evaluated in solution as well as in matrices of various molecular weight and composition after the elaboration of nanocomposites
Soemo, Angela Renee. "Microenvironment of Monorhamnolipid Biosurfactant Aggregates and Monorhamnolipid Effects on Aqueous Dispersion Properties of Metal Oxide Nanoparticles." Diss., The University of Arizona, 2013. http://hdl.handle.net/10150/293563.
Повний текст джерела