Literatura científica selecionada sobre o tema "Assemblages électrostatiques"
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Teses / dissertações sobre o assunto "Assemblages électrostatiques"
Phimphachanh, Anthony. "Synthèse et assemblage électrostatique de copolymères à blocs double-hydrophiles". Thesis, Montpellier, 2018. http://www.theses.fr/2018MONTS031.
Texto completo da fonteDouble-Hydrophilic Block Copolymer (DHBC) based PIC micelles were studied for their suitability as structuring agents for the synthesis of functionalized mesoporous silica materials. Assembling micelles through polyions complexation (PIC) is interesting because it is reversible and restricted to a limited range of pH when weak polyelectrolytes are used. Once silica condensation has proceeded, micelles can be disassembled by changing the pH. In this way, the porosity of the material is revealed by elution rather than calcination. If a controlled fraction of the structuring agent could be maintained within the final material, this would open the road to one pot synthesis of functionalized mesoporous materials. Addressing this challenge relies on a good control over the reversibility of the assembling process of the micelles, over their lyotropic behavior and on the possibility to form corona-mixed micelles from two DHBC carrying different neutral blocks.Several series of DHBC were synthetized by controlled radical polymerization in aqueous phase, either by RAFT for poly(ethylene oxide)-based DHBC, or by MADIX for polyacrylamide-based DHBC. The polyelectrolyte block is polyacrylic acid. The targeted molar masses were achieved and low (RAFT) to medium (MADIX) dispersity were obtained testifying a good control over the polymerization process. Various cationic homopolyelectrolytes, either weak or strong, were used as micellization agents (MA). Acidity constants, condensation ratios and electrophoretic mobilities were determined, first for each polyelectrolyte by its own, and then mixed with its MA in suitable conditions for micellization. Change of the apparent acidity constant reflects equilibrium constant of electrostatic complexation, while excess of conductivity reveals the number of ionic sites that are involved in the complexation of both macromolecules.PIC micelles are few nanometers large (4-15 nm) and gather from ten to one hundred DHBC molecules. They show the typical core-corona structure of polymer self-assemblies. An inverse correlation between the size and the cohesion of the complex is evidenced for the first time. It could be explained by the amount of water inside the micelle coacervate core that should increase when the number of anchoring sites between the oppositely charged macromolecules decreases. Up to a weight fraction of 60 wt% , the PIC micelles do not show any lyotropic mesophases. Finally, mixed PIC micelles certainly form when different DHBC are mixed with an MA, however, the corona looks richer in PEO the closer to the core and richer in PAM at the external rim. Such radial segregation of the corona block is not suitable to ensure enough interaction of PEO with silica and could preclude the use of such mixed micelles as structuring agent for the one pot synthesis of functionalized mesoporous materials. Alternatives are proposed
Loth, Capucine. "Exploring hydrogels based on the self-assembly of a Fmoc-based tripeptide : physicochemical characterization and antibacterial properties". Electronic Thesis or Diss., Strasbourg, 2024. http://www.theses.fr/2024STRAE002.
Texto completo da fonteHydrogels are 3D networks of fibers that retain large amounts of water when swollen. Due to their biocompatibility, they are increasingly used for drug delivery. To develop antibacterial peptide-based hydrogels, this dissertation presents two studies based on the use of a fluorenylmethoxycarbonyl (Fmoc)-protected phosphorylated tripeptide that can self-assemble into a hydrogel. In the first study, different preparation conditions (pH, salt, presence of polysaccharide) were investigated to obtain a self-healing and antibacterial hydrogel capable of releasing an antibiotic, florfenicol. In the second study, a solid-phase peptide and phosphoramidite synthesis strategies were combined to add florfenicol to the Fmoc-protected tyrosine phosphate via a phosphodiester, which can be cleaved by nucleases produced by bacteria. Encouraging results showed the formation of the targeted compound, paving the way for the design of a self-defensive antibacterial peptide
Palleau, Etienne. "Assemblage électrostatique dirigé de nanoparticules colloïdales sur des surfaces par nanoxérographie par microscopie à force atomique". Thesis, Toulouse, INSA, 2011. http://www.theses.fr/2011ISAT0013/document.
Texto completo da fonteThe study of original properties of colloidal nanoparticles and their integration into nanodevices requires their assembly onto specific areas of solid surfaces. The aim of this thesis work is to develop an innovative method for the directed assembly of colloidal nanoparticles: the nanoxerography process by atomic force microscope (AFM). This technique consists in injecting charges into electrets using an AFM tip. The injected charges are then used to electrostatically trap nanoparticles from suspensions onto the surface. In this context, the charge writing and charge decay in PolyMethyMethAcrylate (PMMA) thin films were studied and the charge density of the charged patterns were quantified using Kelvin force microscope (KFM), an electrical mode of AFM. Assemblies of nanoparticles of different nature (metallic, polymeric (organic and inorganic)), with average sizes extending over a large range (2 nm to 1 µm) and controlled zeta potential were obtained on PMMA thin films. This allowed the analysis of assembly mechanisms and demonstration of the excellent performance of the method. Finally, two techniques of parallel charge writing, viz., the electrical microcontact printing and the electrical nanoimprinting were explored with the prospect of extending the nanoxerography process to industrial scale
Agut, Willy. "Conception de nano-objets adaptatifs à base de polypeptides". Thesis, Bordeaux 1, 2008. http://www.theses.fr/2008BOR12319/document.
Texto completo da fonteAbstract
Gestraud, Cecilia. "Synthèse, fonctionnalisation et assemblage de nanodisques d'argent". Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0112.
Texto completo da fonteSilver nanoparticles, used extensively in catalysis, optics and electronics, are now emerging in new applications such as imaging, photonics or chemical and biochemical detection. Among these applications, some require particular morphologies such as rods or disks (conductive films, enhanced Raman spectroscopy) while others mainly involve a large specific surface area such as in heterogeneous catalysis. Anisotropic metal nanoparticles are traditionally produced in two stages, separating the formation of seeds and their growth, in order to better control their morphology. However, the two-stage synthesis makes the transfer on industrial scale difficult because of the long incubation time and the washing steps required. In this context, we decided to focus on the synthesis of anisotropic nanoparticles, in particular silver nanodisks, as well as their assembly in solution and on surfaces. In our work, we adopted an approach that allows to carry out the two stages of the formation of silver nanodisks in the same reaction medium. The principle is based on the use of two reducers, one weak and one strong, with different kinetic reduction rates, allowing the control of anisotropy. This method is simple and fast but requires good control of the experimental parameters. The time between the addition of the two reducers determines the morphology of the formed objects. There is actually an optimal range for this time, which depends particularly on the temperature of the synthesis. In order to vary the optical properties of these nanodisks, different strategies can be considered. We chose to form assemblies both in solution and on surfaces by different deposition techniques. The adsorption of bifunctional organic molecules can provoke the formation of assemblies in solution: one function has an affinity with silver and the other interacts with the free functions of the other nanoparticles through hydrogen or electrostatic bonds for example. Assemblies can also be made on surfaces. We have been working on original deposition method, which allow an oriented assembly of nanodisks through electrostatic forces.We have demonstrated that these assemblies are good candidates for developing micro-structured SERS substrates
Teulon, Lauryanne. "Nouvelles approches pour l'assemblage électrostatique de particules colloïdales par nanoxérographie : du procédé aux applications". Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0044.
Texto completo da fonteOwing to their unique physico-chemical properties, colloidal nanoparticles are building blocks for the creation of plentiful innovative devices. In order to make easier their characterization and to incorporate them into functional nano-devices, it is necessary to perfectly control their directed assemblies onto solid surfaces. In this context, this thesis’ purpose is to simultaneously better understand and optimize the nanoxerography method, which allows electrostatic and selective directing assemblies of nanoparticles onto charged patterns. After an optimization of the nanoxerography process, three specific problematics have been addressed: (1) micron-sized particles assembly. The combined use of numerical simulations and experiments enabled to unveil the key parameters involved in micron-sized particles assembly and to expend the particle size range foreseeable for an assembly by nanoxerography (factor 100). (2) the 3D assembly analysis. The influence of diverse parameters on the 3D assembly of luminescent model nanoparticles was quantified by using a new assembly protocol. The results gave the generic key criterions for the 3D assembly of colloids by nanoxerography. (3) directed assembly of nanogels sensitive to an external environmental stimulus. The use of an optimized protocol allowed elaborating nanogels assemblies interactive with their environment and to sort these nanoparticles onto the same surface
Qi, Ling. "Design of hybrid organic-inorganic nanostructures via electroastic assembly in solutions and at interfaces : structure, organization and functionalities". Paris 6, 2009. http://www.theses.fr/2009PA066213.
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