Orientador: Marisa Masumi Beppu / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-23T04:13:35Z (GMT). No. of bitstreams: 1 Cunha_BrunodaSilva_M.pdf: 5239524 bytes, checksum: a10ce0fe52590b8a60cd2236ffaf0e74 (MD5) Previous issue date: 2013 / Resumo: A contaminação do meio ambiente por metais tóxicos tem levado ao desenvolvimento de pesquisas que busquem adsorventes que possibilitem a retirada em concentrações baixas ("refinada") destes metais com boa eficiência. A quitosana é um polímero natural já estabelecido na literatura como um material que tem a capacidade de adsorver íons metálicos. Transformações químicas, físicas ou a combinação com outros materiais são alternativas utilizadas como mecanismo de viabilizar melhorias. Associar quitosana com outros materiais já é uma técnica utilizada atualmente, porém, devido às necessidades de adequação as tendências de conservação dos ecossistemas e viabilidade de processo, fazem-se necessário o uso de substâncias mais corretas ambientalmente e com uma boa eficiência. Uma classe pouco conhecida por muitos pesquisadores são os líquidos iônicos, estas substâncias possuem propriedades únicas e podem ser aplicados para diferentes fins, inclusive a captura de íons metálicos de sistemas contaminados. Esta pesquisa busca avaliar o efeito dos líquidos iônicos (Formiato de 2-Hidroxietilamônio, Butirato de n-metil-2-Hidroxietilamônio e Hexanoato de n-metil-2-Hidroxietilamônio) combinado às esferas de quitosana porosas na adsorção de íons cobre. Foram realizados estudos cinéticos, isotérmicos e a determinação dos parâmetros termodinâmicos para um melhor entendimento dos sistemas. Os resultados cinéticos demonstram que para todos os sistemas a etapa limitante da taxa de adsorção é a quimissorção e que é necessário um período de 100 horas para se alcançar um equilíbrio. O estudo de isoterma define uma adsorção monocamada com sítios energeticamente homogêneos para as esferas de quitosana e o sistema com o Butirato de n-metil- 2-Hidroxietilamônio adicionado, já para os sistemas com os líquidos iônicos Formiato de 2- Hidroxietilamônio e Hexanoato de n-metil-2-Hidroxietilamônio é definida uma adsorção multicamada com sítios energeticamente heterogêneos. A mudança de energia livre de Gibbs demonstra a natureza espontânea de todos os sistemas. A técnica EXAFS confirmou que a adsorção de íons Cu2+ se dá nos grupos amino e hidroxilas, embora não tenha sido possível diferenciá-los e apresenta modificações nas esferas de coordenação indicando mudanças no mecanismo de adsorção. Concluiu-se que a adição de líquidos iônicos em esferas porosas de quitosana aumentou a capacidade de adsorção de íons Cobre (II) / Abstract: Contamination of the environment by toxic metals has led to the development of research on changes in the properties and characteristics of materials that allow satisfactory efficiency for a withdrawal "refined" these metals. Chitosan is a natural polymer as defined in the literature as a material that has the ability to absorb metal ions. Chemical, physical transformations or combination with other alternative materials are used as a mechanism to enable improvements. Join chitosan with other materials is a technique already widely used, however, because the needs of fitness trends in ecosystem conservation and sustainability of the process, it is necessary the use of substances and more environmentally correct with a good efficiency. A class little known by many researchers are ionic liquids, these substances have unique properties and can be applied for different purposes, including the capture of metal ions doped systems. This study aims to assess the effect of ionic liquids (2-hydroxyethylammonium formate, n-methyl-2- hydroxyethylammonium butyrate and n-methyl-2-hydroxyethylammonium hexanoate) combining the chitosan beads in the adsorption of copper ions. Kinetic studies were carried out, isothermal and determination of thermodynamic parameters for a better understanding of the systems. The kinetic results show that for all systems the rate limiting step for adsorption and chemisorption is that it takes a period of 100 hours to reach equilibrium. The study defines an adsorption isotherm monolayer with energetically homogeneous sites for systems sphere of chitosan and with nmethyl- 2-hydroxyethylammonium butyrate added, for systems with ionic liquids 2- hydroxyethylammonium formate and n-methyl-2-hydroxyethylammonium hexanoate is assigned a multilayer adsorption with energetically heterogeneous sites. The change free energy of Gibbs demonstrates the spontaneous nature of all systems. The EXAFS technique confirmed that the adsorption of Cu2+ occurs in the amino and hydroxyl groups, although it was not possible to differentiate them from each other, showing changes in the coordination spheres indicating changes in the adsorption mechanism. It was concluded that the insertion of ionic liquids in porous beads of chitosan increased the adsorption of ions copper (II) / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

Orientador: Martín Aznar / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-20T15:48:19Z (GMT). No. of bitstreams: 1 Barbosa_MarianaRicken_M.pdf: 3140781 bytes, checksum: ce61206a4ab10df4d9f58d21d2faa257 (MD5) Previous issue date: 2012 / Resumo: Os líquidos iônicos são compostos químicos cujas propriedades termofísicas têm sido estudadas a fim de aplicá-los em diversos processos, tais como o de separação. No caso da destilação, para realizar o projeto, otimização e a operacao do sistema, necessita-se conhecer o equilíbrio liquida-vapor, cujo calculo pode ser realizado por equações de estado cúbicas. Essas expressões contêm parâmetros de atração e repulsão que são dependentes de propriedades críticas, as quais não são possíveis de determinar experimentalmente para os líquidos iônicos, mas podem ser estimadas por grandezas mensuráveis, como, por exemplo, a velocidade do som. Neste trabalho, as propriedades críticas, temperatura de ebulição e os termos atrativo e repulsivo de equações de estado cúbicas para os líquidos iônicos baseados no íon imidazólio [C2mim] [EtSO4], [C2mim] [NTf2], [C6mim] [NTf2], [C5mim] [NTf2], [C4mim] [PF6], [C2mim] [PF6], [C6mim] [PF6], [C8mim] [NTf2], [C8mim] [PF6], [C8mim] [BF4], [C4mim] [BF4], [C6mim] [BF4] e [C4mim] [NTf2], foram determinados a partir de dados de velocidade do som, volume molar e capacidades caloríficas, minimizando uma função objetivo atraves do algoritmo genético PIKAIA. As frações molares da fase liquida do equilíbrio liquida-vapor de sistemas binários incluindo imidazólios foram calculadas pelo software Phase Equilibrium 2000 e comparadas com os dados experimentais. Os líquidos iônicos com anions [BF4]- e [NTf2]- apresentaram resultados similares de ELV para a maioria das equações de estado e regras de mistura quando se utilizou os valores de temperatura normal de ebulição, pressão e temperatura criticas obtidos pelo processo de otimização e pelo método de contribuição de grupo proposto por Valderrama e Rojas (2009). Para os imidazólios contendo íons [PF6]- e [EtSO4]-, os desvios médios relativos para as frações molares na fase liquida foram menores quando se utilizaram as propriedades termofísicas calculadas por velocidade do som e regra de mistura de van der Waals / Abstract: Ionic liquids are chemical compounds whose thermophysical properties have been studied in order to apply them in a large amount of processes, for example, separation process. In case of distillation, one needs to know liquid-vapor equilibria whose determination can be done through cubic equations of state in order to design, optimize and operate the system. In those equations, there are attractive and repulsive parameters which are dependent on critical properties that, for ionic liquids, cannot be experimentally determined but can be estimated by measurable variables, such as speed of sound. In this work, the critical properties, boiling temperature and the attractive and repulsive parameters of cubic equations of state for ionic liquids based on imidazolium [C2mim] [EtSO4], [C2mim] [NTf2], [C6mim] [NTf2], [C5mim] [NTf2], [C4mim] [PF6], [C2mim] [PF6], [C6mim] [PF6], [C8mim] [NTf2], [C8mim] [PF6], [C8mim] [BF4], [C4mim] [BF4], [C6mim] [BF4] e [C4mim] [NTf2], were determined using speed of sound, molar volume and heat capacities data, minimizing an objective function using PIKAIA genetic algorithm. Liquid mole fractions of binary liquid-vapor equilibria with imidazolium were calculated by Phase Equilibrium 2000 software and then compared with experimental data. Ionic liquids with [BF4]- and [NTf2]- anions showed similar results for most of the equations of state and mixing rules when the normal boiling temperature, critical pressure and temperature were used and estimated by an optimization procedure and group contribution method proposed by Valderrama and Rojas (2009). Imidazolium-based ionic liquids with [PF6]- and [EtSO4]- ions had the smallest relative mean deviations of liquid mole fractions when the thermophysical properties were calculated by speed of sound and the van der Waals's mixing rule were used / Mestrado / Desenvolvimento de Processos Químicos / Mestre em Engenharia Química

Various modern spectroscopies have been utilized with considerable success in recent years to probe the dynamics of vibrational and reorientational relaxation of molecules in condensed phases. We have studied the temperature dependence of the polarized and depolarized Raman spectra of various modes in the following dihalomethanes: dibromomethane, dichloromethane, dichloromethane-d2, and bromochloromethane. Among other observed trends, we have found the following: Vibrational dephasing times calculated from the bend) and (C-Br stretch) lineshapes are of the same magnitude in CI^B^. The vibrational dephasing time of [C-D(H) stretch] is twice as long in CD2Cl2 as in CH-^C^, and the relaxation time of (C-Cl stretch) is greater in CI^C^ than in CD2CI2. Isotropic relaxation times for all three stretching vibrations are significantly shorter in C^BrCl than in CI^C^ or CI^B^. Application of the Kubo model revealed that derived modulation times are close to equal for equivalent vibrations in the various dihalomethanes. Thus, the more efficient relaxation of the A^ modes in CE^BrCl can be attributed almost entirely to the broader mean squared frequency perturbation of the vibrations in this molecule.

In order to explore the N-H stretching region of aliphatic amines, we performed a study of the Raman spectrum of n-propylamine at various concentrations in cyclohexane. Statistical analysis provided evidence of a second symmetric stretching vibration, which we were able to assign to nonhydrogen bonded NH2 groups. To obtain additional evidence on the existence of monomers in n-propylamine and to further study hydrogen bonding and Fermi resonance in aliphatic amines, we extended the investigation to the analysis of the Raman spectrum of this compound over an extended range of temperature in the neat liquid phase. This study corroborated our finding that the peak previously assigned to the symmetric stretching mode of hydrogen bonded amines is actually composed of two bands. Furthermore, trends in both the resolved band parameters and the Fermi resonance analysis were tabulated, allowing one to monitor the change in the N-H valence region with concentration and temperature.

Afin de s’affranchir de contraintes liées à l’utilisation de milieux conventionnels, l’électroreduction du CO2 a été étudiée en milieux liquides ioniques. L’activité de l’interface électrode - électrolyte a été examinée par techniques électrochimiques et les produits de réactions formés après électrolyses sous contrôle potentiostatique, ont été analysés par techniques chromatographiques et spectroscopie RMN. L’ensemble des informations obtenu lors de ces analyses a permis de contribuer à une meilleure compréhension des mécanismes réactionnels de l’électroréduction du CO2 en milieux liquides ioniques. Au travers de ce travail, l’influence de la composition du liquide ionique sur l’électroréduction du CO2 conduite à une électrode d’or a pu être étudiée, en recourant à des liquides ioniques constitués de différents cations (imidazolium, pyrrolidinium, pipéridinium et tétraalkylammonium) et du même anion [NTf2]-. En milieu [BMIm][NTf2], la présence du proton acide H-2 du cation [BMIm]+ favorise la formation de CO, principal produit formé à l’électrode d’or polycristallin. Cependant, la réduction du cation [BMIm]+ apparaît comme une réaction compétitive, produisant non seulement du carbène, mais également des dimères hydrogénés et un monomère. La différence de sélectivité de ces produits observée à différents matériaux d’électrode a pu être interprétée sur base des capacités différentes des surfaces métalliques à adsorber l’hydrogène. En présence de ces produits générés électrochimiquement, le CO2 est indirectement converti produisant en partie un adduit. Dû fait de la faible chargée transféree durant électrolyse en milieu [N1,1,1,3][NTf2] et des grandes surtensions nécessaires à la réduction du CO2 en milieu [PMPip][NTf2], l’électroréduction du CO2 a été poursuivie en détail en milieu [BMPyrr][NTf2].En milieu [BMPyrr][NTf2], la réduction du cation n’apparaît plus comme une réaction compétitive, et CO peut être formé sélectivement avec d’excellentes efficacités faradiques, sans consommation des protons du liquide ionique. Dans ce milieu, la formation de CO est seulement inhibée à des potentiels plus négatifs par la formation d’oxalate, la dégradation de l’anion [NTf2]- et par la corrosion cathodique de l’électrode d’or. De plus, le présent travail a montré que la sélectivité pour la formation de CO et d’oxalate est affectée par la nature du matériau d’électrode, grâce à l’utilisation d’une surface de cuivre. A une électrode de cuivre polycristallin, la présence d’une source de proton, telle que H[NTf2], permet également la formation de produits à haute valeur ajoutée, telle que le méthane ou l’acide formique.A une électrode d’or polycristallin, la formation d’adduits en présence de CO2 n’a pas seulement été observée en milieu [BMIm][NTf2], mais également après ajout d’un co-réactant, telle que des bipyridines, en milieu [BMPyrr][NTf2]. Le mécanisme de réaction diffère cependant selon la structure de la bipyridine. / To avoid limitations encountered in conventional media, the electroreduction of CO2 has been studied in ionic liquids. The activity of the ionic liquid - electrode interface was examined by electrochemical techniques and the reaction products were analysed after controlled-potential electrolysis, by chromatographic techniques and NMR spectroscopy. The information obtained by these analysis have contributed to a better understanding of the reaction pathways of the electroreduction of CO2 in ionic liquids media. In this work, the influence of the ionic liquid composition on the electroreduction of CO2 conducted at gold electrodes was studied by resorting to ionic liquids composed of different cations ( imidazolium, pyrrolidinium, piperidinium and tetraalkylammonium) and the same anion [NTf2]−. In [BMIm][NTf2], the presence of acidic H-2 proton on the [BMIm]+ cation favours the formation of CO, main product formed at Au (poly). However, the reduction of the [BMIm]+ cation appears as a competitive reaction, producing not only carbene, but also hydrogenated dimers and a monomer. The selectivity of these electrogenerated products observed at various electrode materials, has been interpreted taking into account the distinct H-adsorption abilities of the metallic surfaces. In the presence of these electrogenerated products, CO2 is indirectly converted into an adduct. In ammonium-based ionic liquids, the electroreduction has been investigated in detail only in [BMPyrr][NTf2], since inhibition of the charge transfer and a high overpotential for the reduction of CO2 were observed in [N1,1,1,3][NTf2] and [PMPip][NTf2], respectively.By contrast, in [BMPyrr][NTf2], presenting no reduction reaction of the cation in competition with the CO2 electroreduction at Au (poly), the formation of CO can be selectively formed with excellent faradaic efficiency and without consumption of the RTILs protons. The selectivity for the formation of CO only decreases at more negative potentials, since the formation of oxalate, the decomposition of the [NTf2]- anion and a cathodic corrosion of the gold electrode may also take place. It has been shown that the selectivity for the formation of CO and oxalate is affected by the nature of the electrode material, using a copper surface. At Cu (poly), the presence of an additional source of proton, such as H[NTf2], to [BMPyrr][NTf2] also provides the formation of methane or formic acid.At Au (poly), the formation of adducts in the presence of CO2 has not only been observed in [BMIm][NTf2], but also after the addition of co-reactant, such as bipyridines, in [BMPyrr][NTf2]. The reaction mechanism differs, however, according to the structure of bipyridine. / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Ce travail porte sur l’étude électrochimique de l’interface formée par une électrode d’or plongée dans le liquide ionique 1-butyl-3-methylimidazolium dicyanamide ou [BMIm][DCA]. Ce liquide ionique a été sélectionné car outre sa conductivité intrinsèque, il permet de solubiliser aisément des sels de métaux de transition à température ambiante. Les liquides ioniques sont, par définition, des sels liquides en dessous de 100 °C et la plupart d’entre eux sont liquides à température ambiante. Etant donné que les liquides ioniques sont constitués majoritairement d’ions, la description de la double couche électrique telle que décrite dans les électrolytes traditionnels doit être reconsidérée.<p>Deux grandes thématiques fondamentales sont abordées dans ce travail :le comportement de la double couche électrique à l’interface liquide ionique / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work describes the synthesis of a series of pyrazoles from enaminoketones (RC(O)CH=CHNMe2 where R = hexyl, dimethoxymethyl, Ph, 4-Me-C6H4 4-F-C6H4, 4-Cl-C6H4, 4-Br-C6H4, 4-O2N-C6H4, thien-2-yl, fur-2-yl, pyrrol-2-yl, pyridin-2-yl) and N-tert-butilhidrazine hydrochloride. In order to get the best reaction media, reactions were carried out in different ionic liquids such as: [BMIM][BF4], [BMIM][Br], [OMIM][BF4], [BMIM][PF6], [DBMIM][Br], [DBMIM][BF4], [BMIM][OH], [BMIM][SCN], [HMIM][HSO4] and [HMIM][CF3CO2], with different physical and chemical. The behavior of each type of ionic liquid was discussed and the best yield for the cyclocondensation reactions studied was obtained using [BMIM][BF4]. Furthermore, also was a series of pyrazoles from the enones ([CF3C(O)CH=C(R)(OR1], where R1 = Me, Et and R = H, Me, Ph, 4-Me-C6H4, 4-MeOC6H4, 4-F-C6H4, 4-Cl-C6H4, 4-Br-C6H4, fur-2-yl, thien-2-yl and naphthalen-2-yl) and hydrochloride N-tert-butilhydrazine in the presence of pyridine was obtained. The products were obtained as a mixture of isomers. In some cases, it was possible to separate the isomers by washed with hexane. One of the crystalline compounds was analyzed by X-ray diffraction to confirm its structure. / Este trabalho descreve a síntese de uma série de pirazóis a partir da reação de enaminonas (RC(O)CH=CHNMe2 onde R = hexil, dimetoximetil, Ph, 4-Me-C6H4, 4-F-C6H4, 4-Cl-C6H4, 4-Br-C6H4, 4-O2N-C6H4, tien-2-il, fur-2-il, pirrol-2-il, piridin-2-il) com cloridrato de N-tert-butilhidrazina. A fim de estabelecer as melhores condições para a reação, foram testados diferentes líquidos iônicos ([BMIM][BF4], [BMIM][Br], [OMIM][BF4], [BMIM][PF6], [DBMIM][Br], [DBMIM][BF4], [BMIM][OH], [BMIM][SCN], [HMIM][HSO4] e [HMIM][CF3CO2]) com propriedades físicas e químicas diferentes. O comportamento de cada tipo de líquido iônico foi discutido e o melhor rendimento para a reação de ciclocondensação estudada foi obtido utilizando [BMIM][BF4]. Além disso, foram sintetizados N-tert-pirazóis a partir da reação de enonas trifluormetiladas ([CF3C(O)CH=C(R)(OR1], onde R1 = Me, Et e R = H, Me, Ph, 4-Me- C6H4, 4-MeO-C6H4, 4-F-C6H4, 4-Cl-C6H4, 4-Br-C6H4, fur-2-il, tien-2-il e naftil) com cloridrato de N-tert-butilhidrazina na presença de piridina e LI. Os produtos foram obtidos como uma mistura de isômeros. Em alguns casos foi possível a separação da mistura isomérica por lavagem com hexano. Um dos compostos cristalinos foi analisado por Difratometria de Raios-X para confirmar a sua estrutura.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第17065号 / 工博第3614号 / 新制||工||1548(附属図書館) / 29785 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 佐藤 啓文, 教授 白川 昌宏, 教授 山本 量一 / 学位規則第4条第1項該当

Les liquides ioniques (LIs) sont des nouveaux solvants ioniques, de plus en plus utilisés dans des systèmes à base de nanoparticules (NP) pour plusieurs applications industrielles et technologiques. Pourtant, à présent nous ne sommes pas en mesure de maîtriser l'état de dispersion ou agrégation des NP dans ces solvants, et les lois classiques sur la stabilité colloïdale, telles que la DLVO, ne sont pas adaptées à cet effet. La difficulté se retrouve notamment dans la description des interactions électrostatiques dans ces milieux ioniques. Dans ce travail, nous essayons de mieux comprendre les interactions colloïdales dans les LIs à travers deux systèmes bien caractérisés séparément : les nanoparticules magnétiques de maghémite, dont la surface est bien contrôlée dans l'eau, et le liquide ionique nitrate d'éthylammonium (NEA), qui est connu pour sa ressemblance avec l'eau. Les deux systèmes sont mélangés et étudiés aux niveaux macroscopique et microscopique. Nous effectuons des caractérisations à travers plusieurs techniques : absorption atomique de flamme, microscopie optique sous champ magnétique, diffusion de rayonnement (neutrons, rayons X et lumière), biréfringence magnéto-optique. Nous découvrons l'importance d'avoir une surface de NP chargée pour obtenir des dispersions stables de maghémite dans le NEA. En particulier, la meilleure stabilité colloïdale est atteinte en adsorbant des molécules de citrate sur la surface des NP. Nous étudions ensuite l'effet de la taille et concentration des NP, du contreion cationique qui compense la charge du citrate, du contenu d'eau. Enfin, nous transférons nos protocoles à la réalisation de dispersions dans des LI biocompatibles. / Ionic liquids (ILs) are a novel class of ionic solvents, which are being used more and more often in chemical systems based on nanoparticles (NP) for several industrial and technological applications. However, at present we are unable to master the state of dispersion or aggregation of NP in these solvents, and the classic theories applied to colloidal stability, such as the DLVO, cannot be applied. In particular, the difficulty is found in the description of the electrostatic interactions in these ionic media. In this work, we try to better understand colloidal interactions in ILs through two systems that have been thoroughly characterized separately: magnetic maghemite nanoparticles, whose surface is well controlled in water, and the ionic liquid ethylammonium nitrate (EAN), known for its resemblance to water. These two systems are finally mixed together and studied at both the macroscopic and microscopic levels. We perform characterizations through several techniques: flame atomic absorption spectroscopy, optical microscopy under magnetic field, scattering methods (neutrons, X-rays and light), magneto-optic birefringence. We discover the importance of having a charged NP surface in order to obtain stable maghemite dispersions in EAN. In particular, the best colloidal stability is reached by adsorbing citrate molecules on the NP surface. We further investigate the effect of the NP's size and concentration, of the cationic counterion used to compensate the charge of citrate, of water content. Finally, we transfer our acquired knowledge to the realization of dispersions in biocompatible ILs.

L'hyperthermie magnétique est une technique de traitement de cancers en plein essor. Cette conversion d'une énergie électromagnétique en énergie thermique par des nanoparticules soumises à une excitation magnétique oscillant à haute fréquence est étudiée depuis près de deux décennies mais elle est encore mal décrite pour des systèmes complexes.Le travail présenté ici s'attache à compléter la connaissance de ce phénomène en reliant l'état de dispersion de nanoparticules à leurs propriétés d'hyperthermie.Tout d'abord sont présentés la caractérisation et le contrôle de dispersions dans des milieux complexes tels qu'un liquide ionique ou une matrice polymère.En effet, l'obtention d'une dispersion colloïdalement stable dans un liquide ionique soulève de nombreux défis. Une étude approfondie du rôle de la charge de surface des particules, contrôlée à l'aide du pH dans un liquide ionique protique, a permis de mieux comprendre le rôle du solvant et la nature des interactions dans ce type de milieu.En outre, disperser finement des nanoparticules hydrophiles dans une matrice hydrophobe telle qu'une matrice siliconée est également une tâche délicate et une méthode nouvelle d'évaporation d'émulsion ferrofluide-dans-matrice polymère est présentée ici, ainsi que l'étude des dispersions ainsi obtenues.Enfin est exposée une étude du pouvoir chauffant de nanoparticules dans des états de dispersion variés, faisant notamment intervenir une méthode de mesure développée dans le cadre de cette thèse. Ces résultats soulignent l'influence de l'agrégation des particules qui provoque une baisse significative de leur échauffement ainsi que le rôle clef de la compacité des agrégats formés. / Magnetic hyperthermia is a promising therapeutic technique against cancer. It consists in turning electromagnetic energy into heat thanks to nanoparticles that are excited by a radiofrequency oscillating magnetic field. Although this phenomenon has been studied for more than two decades, it remains poorly described. This work aims at filling the gap of knowledge about magnetic hyperthermia through the study of the correlations between the dispersion state and the heating efficiency of the particles. The characterisation and the control of dispersions in complex media such as ionic liquids or a polymer matrix is dealt with in the first part. Obtaining a colloidally stable dispersion in an ionic liquid proves indeed a challenging task. The particles surface charge can be controlled in a protic ionic liquid by tuning the pH. A thorough study of the influence of this parameter allowed a better insight into the role of the solvent and the nature of the interactions. Furthermore, the formation of a fine dispersion of hydrophilic nanoparticles in a hydrophobic silicon matrix is also a ticklish task. A new method is presented here, that consists in the evaporation of a ferrofluid-in-polymer matrix emulsion. The dispersion state of the resulting materials is then characterised.The heating efficiency of particles showing different dispersion states is studied in the last part. It includes results obtained with a new measurement method developed in the scope of this thesis. These results highlight that the particles aggregation causes a decrease of their heating properties. They also evidence the key role of the aggregates compactness in this respect.