High performance catalyst supports and packing materials are playing an increasing role in many reactions and separations. The dispersion in packed bed reactors and separation columns can be reduced by the development of new packing structures having open and connected pore geometries. The application of new materials in High Performance Liquid Chromatography (HPLC) with sub 5 micron particle sizes are growing. These small particles offer better performance and improved bed and column efficiencies. Recently developed, twinned Alumina Nanosheets (TAN) are 2D/3D nanomaterials that offer promising open geometries for use as column packings and catalysts supports. They have a small particle size (4 um in length, 1 um in width and 0.1 um in thickness) and excellent flow-through capabilities. TANs have recently been used to successfully produce high throughput dynamic membranes. However, their resistance to compaction is unknown and thought to be limited. A technique was developed to reinforce the TAN nanomaterial. Two binder materials were tested as reinforcing agents; SiO2 and AlH6O12P3. The binder-reinforced TANs were then packed into columns. Eleven columns having a 4 cm initial packing length were assembled. Tracer injection studies were performed to investigate the flow behavior and dispersion in these columns. SEM images were also taken to characterize the particles before and after compaction. The best results were obtained using a binding solution containing 7.5 (wt%) SiO2. The binder SiO2 offered a better resistance to compaction than the AlH6O12P3. The Peclet (Pe) number for the columns ranged from 22 to 648. When the content of SiO2 increased from 0 to 7.5 (wt%), the columns showed an increase in the Pe number. When SiO2 increased from 7.5 to 20 (wt%), the columns showed a decrease in the Pe number. However, AlH6O12P3 did not present any relation between the binder content and the Pe number. The results of this work demonstrate that reinforced TANs, are a new type of material that offers a packing with an open pore structure and improved channel connectivity. The new reinforced material offers considerable potential in many applications such as catalysis and separations over conventional materials. If they are used as packing materials in HPLC columns or packed bed reactors, they can contribute to a higher separation efficiency or an enhanced conversion rate or productivity, bringing more advantages and benefits than ordinary packing materials.

Graphene nanoplatelets (GNP) with thickness of 6 ~ 8 nm and lateral dimension of 5 μm (M5) and 25 μm (M25) have been used to prepare epoxy composites. Epoxy composites were fabricated initially by shear mixing to investigate the effects of filler type on the structure and properties of composites. The complex viscosity of GNP-epoxy mixture was found to increase by almost three orders of magnitude going from the neat epoxy to the 8 wt.% loading, leading to difficulties in their processing. Scanning electron microscopy of the composites showed that both fillers aggregated at high loadings with the M25 buckling more easily due to its larger diameter, which compromises its aspect ratio advantage over M5, resulting in only slightly better mechanical performance. Polarized Raman spectroscopy revealed that both M5 and M25 were randomly distributed in the epoxy matrix, After adding M5 and M25 fillers, the storage modulus increase with the filler loadings, however, the glass transition temperature (Tg) drops slightly after initial incorporation, then rises with further filler addition attributed to the pin effects of filler aggregations. In terms of electrical property, M25 has lower percolation (1 wt.%) than M5 composites due to its bigger aspect ratio, which enable M25 to form a conductive network more efficiently. Furthermore, M25 composites also have slightly better thermal and mechanical properties over that of M5 composites. However, the difference is not significant considering the aspect ratio of M25 is five times of that of M5. The reason is that the aggregation and buckling of M25 compromise its advantage over M5. Due to the better performance of M25 as filler, M25/epoxy composites were prepared by shear mixing, solvent compounding and three-roll mill. Samples made by solvent compounding display the lowest percolation threshold (0.5 wt.%), related to its relatively uniform dispersion of M25 in matrix, resulting in higher thermal conductivity and better mechanical properties. Water uptake in a water bath at 50 °C took 75 days to be saturated. Higher loaded samples have lower diffusion coefficient because of the barrier effects of GNP fillers, but have higher maximum water absorbed, which is owing to filler aggregation. Properties test of aged and unaged specimens show thermal conductivity of the aged was enhanced due to water’s higher thermal conductivity than epoxy resin matrix, while electrical performance was compromised due to the swelling effects caused by absorbed water. The mechanical properties of aged samples also dropped slightly due to plasticization effects.

Solid-state lightings are becoming the popular choice for lightings due to its higher efficiency, improved colour rendering index and the flexibility of various size and shape. Halide perovskite has tunable colour emission, low disorder and is solution processable making it one of a popular choice as emitters. This thesis demonstrates the versatility of using halide perovskite material in light-emitting diodes. We demonstrate the first working perovskite light-emitting diode at room temperature by introducing thin layer of perovskite emitter which is crucial to confine the inherent free carriers in the material. We show that the 3D lead-halide bulk perovskite is bandgap tunable with emission in the green and red visible spectrum. Light-emitting diodes in the visible spectrum are common however near-infrared emission is a rarity. Lead is a heavy metal which is known for its toxicity. We tackled the issue of toxicity by replacing with tin and demonstrate tunable emission in the near-infrared region. Bulk perovskites have large binding energy which makes it difficult to confine the charges and form radiative recombination which is crucial for emission and efficiency of the device. We move into lower dimensionality perovskites by utilising all-inorganic perovskite nanoplatelets and show emission in the blue region.

Carbon nanotubes (CNTs) and graphite nanoplatelets (GNPs) are carrying great promise as two important constituents of future multifunctional materials. Originating from their minimal defect confined nanostructure, exceptional thermal and electrical properties have been reported for these two allotropic forms of carbon. However, a brief survey of the literature reveals the fact that the incorporation of these species into a polymer matrix enhances its effective properties usually not to the degree predicted by the composite\\textquoteright s upper bound rule. To exploit their full potential, a proper understanding of the physical laws characterizing their behavior is an essential step. With emphasis on the electrical and thermal properties, the following study is an attempt to provide more realistic physical and computational models for studying the transport properties of these nanomaterials. Originated from quantum confinement effects, electron tunneling is believed to be an important phenomenon in determining the electrical properties of nanocomposites comprising CNTs and GNPs. To assess its importance, in this dissertation this phenomenon is incorporated into simulations by utilizing tools from statistical physics. A qualitative parametric study was carried out to demonstrate its dominating importance. Furthermore, a model is adopted from the literature and extended to quantify the electrical conductivity of these nanocomposite. To establish its validity, the model predictions were compared with relevant published findings in the literature. The applicability of the proposed model is confirmed for both CNTs and GNPs. To predict the thermal properties, a statistical continuum based model, originally developed for two-phase composites, is adopted and extended to describe multiphase nanocomposites with high contrast between the transport properties of the constituents. The adopted model is a third order strong-contrast expansion which directly links the thermal properties of the composite to the thermal properties of its constituents by considering the microstructural effects. In this approach, a specimen of the composite is assumed to be confined into a reference medium with known properties subjected to a temperature field in the infinity to predict its effective thermal properties. It was noticed that such approach is highly sensitive to the properties of the reference medium. To overcome this shortcoming, a technique to properly select the reference medium properties was developed. For verification purpose the proposed model predictions were compared with the corresponding finite element calculations for nanocomposites comprising cylindrical and disk-shaped nanoparticles. To shed more light on some conflicting reports about the performance of the hybrid CNT/GNP/polymer nanocomposites, an experimental study was conducted to study a hybrid ternary system. CNT/polymer, GNP/polymer and CNT/GNP/polymer nanocomposite specimens were processed and tested to evaluate their thermal and electrical conductivities. It was observed that the hybrid CNT/GNP/polymer composites outperform polymer composites loaded solely with CNTs or GNPs. Finally, the experimental findings were utilized to serve as basis to validate the models developed in this dissertation. The experimental study was utilized to reduce the modeling uncertainties and the computational predictions of the proposed models were compared with the experimental measurements. Acceptable agreements between the model predictions and experimental data were observed and explained in light of the experimental observations. The work proposed herein will enable significant advancement in understanding the physical phenomena behind the enhanced electrical and thermal conductivities of polymer nanocomposites specifically CNT/GNP/polymer nanocomposites. The dissertation results offer means to tune-up the electrical and thermal properties of the polymer nanocomposite materials to further enhance their performance. / Ph. D.

En esta Tesis Doctoral, las heterouniones de grafeno con otros materiales 2D y nanopartículas metálicas, incluyendo (N)grafeno/h-BN, grafeno/MoS2 y grafeno depositado Fe/Co, se sintetizaron en base al uso de polisacáridos naturales como precursors de grafeno. Estos materials se caracterizaron usando diversos métodos analíticos y se ensayaron para determinar el acoplamiento C-N oxidativo de las amidas, la hidrogenación de CO2 o la aplicación catalítica fotoeléctrica y física. En la primera etapa de la tesis, se estudió la influencia de la temperatura y la presencia de H2 durante la pirólisis en la calidad del grafeno. Se observó que una disminución significativa en la densidad de defectos relacionados con la presencia de oxígeno residual se puede lograr cuando el producto se preparó a la temperatura óptima (1100 oC) bajo un bajo porcentaje de H2 (5%). Esta mejora en la calidad del grafeno defectuoso resultante se reflejó en una disminución de la resistencia eléctrica y una mayor actividad fotoeléctrica. En el caso de las heteroestructuras de grafeno dopadas con N/h-BN, se ha revelado que se produjeron capas de segregación espontánea (N)grafeno y nitruro de boro durante la pirólisis. Aunque las heteroestructuras resultantes no mostraron una mejora en la conductividad, el material podría comportarse como un condensador que almacena carga en el rango de voltajes positivos. El grafeno/MoS2 se preparó por pirólisis de ácido algínico que contenía (NH4)2MoS4 adsorbido. Las nanopartículas de MoS2 exhibieron una orientación preferencial en la cara 002, como resultado del efecto de plantilla de las capas de grafeno. Este material exhibió actividad para la reacción de evolución H2, aunque se ha observado alguna variación de la actividad electrocatalítica de un lote a otro. También se prepararon Fe, Co NP o aleaciones Fe-Co incrustadas en matriz carbonosa por pirólisis de polvos de quitosano que contenían iones Fe2+ y Co2+ a 900 oC en atmósfera de Ar y se usaron para el acoplamiento oxidativo de C-N de amidas y compuestos aromáticos de N-H. Se observó que la adición secuencial de dos alícuotas de hidroperóxido de terc-butilo (TBHP) en un exceso de N,N-dimetilacetamida (DMA) como disolvente proporcionaba el correspondiente producto de acoplamiento en altos rendimientos, y el catalizador más eficiente era FeNP@C con alta reutilización y un amplio alcance. Finalmente, las perlas de matriz de carbono grafítico que contienen Fe, Co NPs o aleaciones de Fe-Co se sintetizaron secuencialmente mediante pirólisis en una etapa a 900 oC de perlas de quitosano que tenían acetatos de hierro y cobalto adsorbidos. La mejor muestra, Fe-Co aleación/G (Fe/Co alrededor de 0.4), mostró alta actividad para la hidrogenación de CO2 a isobutano con una selectividad superior al 92% y una conversión de CO2 de aproximadamente el 87%. / In this Doctoral Thesis, the heterojunctions of graphenes with other 2D materials and metal nanoparticles, including (N)graphene/h-BN, graphene/MoS2 and Fe/Co deposited graphene, were synthesized based on using natural polysaccharides as graphene precursors. These materials were characterized using various analytical methods and were tested for oxidative C-N coupling of amides, CO2 hydrogenation or physical and photoelectric catalytic application. In the first stage of the thesis, the influence of temperature and the presence of H2 during pyrolysis on the quality of graphene was studied. It was observed that a significant decrease in the density of defects related to the presence of residual oxygen can be achieved when the produce was performed at the optimal temperature (1100 oC) under a low percentage of H2 (5%). This improvement in the quality of the resulting defective graphene was reflected in a decrease in the electrical resistance and increased photoelectric activity. In the case of N-doped graphene/h-BN heterostructures, it has been revealed that a spontaneous segregation (N)graphene and boron nitride layers took place during the pyrolysis. Although the resulting heterostructures did not show an improvement in the conductivity, the material could behavior as capacitor storing charge in the range of positive voltages. Graphene/MoS2 was prepared by pyrolysis of alginic acid containing adsorbed (NH4)2MoS4. The MoS2 nanoparticles exhibited a preferential 002 facet orientation, as a result of the template effect of graphene layers. This material exhibited activity for H2 evolution reaction, although some variation of the electrocatalytic activity has been observed from batch to batch. Fe, Co NPs or Fe-Co alloys embedded in carbonaceous matrix were also prepared by pyrolysis of chitosan powders containing Fe2+ and Co2+ ions at 900 oC under Ar atmosphere and used for the oxidative C-N coupling of amides and aromatic N-H compounds. It was observed that sequential addition of two aliquots of tert-butyl hydroperoxide (TBHP) in an excess of N,N-dimethylacetamide (DMA) as solvent afforded the corresponding coupling product in high yields, and the most efficient catalyst was FeNP@C with high reusability and a wide scope. Finally, beads of graphitic carbon matrix containing Fe, Co NPs or Fe-Co alloys were sequentially synthesized by one-step pyrolysis at 900 oC of chitosan beads having adsorbed iron and cobalt acetates. The best sample, Fe-Co alloy/G (Fe/Co about 0.4), showed high activity for the hydrogenation of CO2 to isobutane with a selectivity higher than 92 % and a CO2 conversion about 87%. / En esta Tesi Doctoral, les heterounions de grafeno amb altres materials 2D i nanopartícules metàl·liques, incloent (N)grafé/h-BN, grafé/MoS2 i grafé depositat Fe/Co, es van sintetitzar basant-se en l'ús de polisacàrids naturals com precursors de grafé. Estos materials es van caracteritzar usant diversos mètodes analítics i es van assajar per a determinar l'adaptament C-N oxidatiu de les amides, la hidrogenació de CO2 o l'aplicació catalítica fotoelèctrica i física. En la primera etapa de la tesi, es va estudiar la influència de la temperatura i la presència de H2 durant la piròlisi en la qualitat del grafé. Es va observar que una disminució significativa en la densitat de defectes relacionats amb la presència d'oxigen residual es pot aconseguir quan el producte es va preparar a la temperatura òptima (1100 oC) davall un baix percentatge de H2 (5%) . Esta millora en la qualitat del grafé defectuós resultant es va reflectir en una disminució de la resistència elèctrica i una major activitat fotoelèctrica. En el cas de les heteroestructures de grafé dopades amb N/h-BN, s'ha revelat que es van produir capes de segregació espontània (N)grafé i nitrur de bor durant la piròlisi. Encara que les heteroestructures resultants no van mostrar una millora en la conductivitat, el material podria comportar-se com un condensador que emmagatzema càrrega en el rang de voltatges positius. El grafé/MoS2 es va preparar per piròlisi d'àcid algínic que contenia (NH4)2MoS4 adsorbit. Les nanopartícules de MoS2 van exhibir una orientació preferencial en la cara 002, com resultat de l'efecte de plantilla de les capes de grafé. Este material va exhibir activitat per a la reacció d'evolució H2, encara que s'ha observat alguna variació de l'activitat electrocatalítica d'un lot a un altre. També es van preparar Fe, Co NP o aliatges Fe-Co incrustades en matriu carbonosa per piròlisi de pols de quitosano que contenien ions Fe2+ i Co2+ a 900 oC en atmosfera d'Ar i es van usar per a l'acoblament oxidatiu de C-N d'amides i compostos aromàtics de NH. Es va observar que l'addició seqüencial de dos alíquotes de hidroperóxid de terc-butil (TBHP) en un excés de N,N-dimetilacetamida (DMA) com a dissolvent proporcionava el corresponent producte d'acoblament en alts rendiments, i el catalitzador més eficient era FeNP@C amb alta reutilització i un ampli abast. Finalment, les perles de matriu de carboni grafític que contenen Fe, Co NPs o aliatges de Fe-Co es van sintetitzar seqüencialment per mitjà de piròlisi en una etapa a 900 oC de perles de quitosano que tenien acetats de ferro i cobalt adsorbits. La millor mostra, Fe-Co aliatge/G (Fe/Co al voltant de 0.4), va mostrar alta activitat per a la hidrogenació de CO2 a isobutà amb una selectivitat superior al 92% i una conversió de CO2 d'aproximadament el 87%. / He, J. (2018). Heterojunctions of defective graphenes with 2D materials and metal nanoplatelets: preparation and catalytic applications [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/111923

In the present study the effects of addition of organically functionalized boehmite nano-particles on the mechanical properties of epoxy polymers were analyzed. Nanosize platelets of boehmite powders were produced via a hydrothermal process from the raw material aluminum trihydroxide Al(OH)3 provided by a a chemical supplier, but which in future studies can be replaced by local resources of aluminum trihydroxide available in Seydisehir, Turkey. The ground aluminum trihydroxide particles were submitted to a two-step preliminary ageing procedure in different pH media. Particles were then converted to boehmite nanoparticles via hydrothermal ageing at high pressure and temperature. The product&lsquo / s chemical identity, size, structure and morphology were characterized with XRD, FT-IR, SEM and PSA analyses. By controlling the pH and the ageing time as parameters, hexagonal shaped nanoplatelets were obtained with dimensions ranging from 100 to 500 nm. Aiming at using these nanoparticles into surface coating polymers, the most favorable shape is the plate-like morphology, leading to adopting the last hydrothermal condition in the rest of the study. v The boehmite crystal surfaces are furnished with hydroxyls which can potentially be reacted with epoxy monomers of bisphenol A diglycidyl ether with the help of tin (II) chloride as catalyst through ring-opening reactions. The FT-IR and quantitative analyses indicated that this surface functionalization is possible under a temperature 80 oC and a weight ratio of 5:1 epoxy monomer to boehmite powder These novel inorganic/organic hybrid materials were then mixed with epoxy/hardener resin mixture to obtain nanocomposites. The properties of the composites were characterized accordingly with tensile, impact, micro hardness, micro-scratch tests, DMA analysis and observed with SEM analysis. A deterioration of the tensile strength from the neat polymer was observed, with a distinct trend between the functionalized and non-functionalized boehmite-epoxy polymers. The functionalized polymers showed a less deteriorative character. The tensile modulus instead showed a little improvement of (4%) in 5wt% loaded polymers. DMA analysis results revealed an improved glass transition temperature in the nanocomposites as well as in storage and loss modulus. As aimed in this work, the functionalized boehmite-epoxy polymers displayed a clear improvement in comparison to both non-functionalized and neat polymers in surface coating properties in hardness and scratch resistance.

Made available in DSpace on 2016-06-02T19:19:58Z (GMT). No. of bitstreams: 1 MELLO_Waldomiro_2014.pdf: 2920239 bytes, checksum: a0ba2a82065620b41788d178ed20df21 (MD5) Previous issue date: 2014-11-29 / In this work we have compared the way graphene oxide nanoplatelets are nanostructured in bilayers of poly(diallyldimethylammonium chloride) (PDDA) and reduced graphene oxide stabilized in poly(sodium 4-styrenesulfonate) (GPSS), called as (PDDA-GPSS)n, with n representing the number of deposited bilayers. LbL (layer-by-layer) films were fabricated by the self-assembly technique throughout the dipping, spray and dynamic methodologies, available at Laboratory FINEP1, UFSCar, campus Sorocaba. When compared with other bottom-up strategies employed in the build-up of nanostructured ultrathin films, the LbL technique is simple, cheap and easy to handle, beside the incorporation of distinct materials in the film structure, not limited to the form and size of substrates. The times used for the polyelectrolytes in the dipping and dynamic methods were based on the kinetic growth of the (PDDA-GPSS)8 films. In the spray methodology the time used was based initially in the literature and further confirmed by experimental data considering pressure and spray time. All nanostructures formed were characterized by UV-vis spectroscopy, atomic force microscopy, scanning electron microscopy, profilometry and impedance spectroscopy. In all cases it was observed a linear growth of the LbL structures, pointing that the same amount of material was adsorbed at each deposition step. Films obtained from the dynamic methodology indicated higher amount of material adsorbed in the nanostructures, and by an adequate control of the parameters used in the self-assembly methods by physical adsorption one can make a fine tuning regarding to the spontaneous aggregation of the nanoplatelets at solid interfaces. / Neste trabalho comparamos a forma com a qual as nanofolhas de grafeno são nanoestruturadas em bicamadas de poli(cloreto de dialildimetilamônio) (PDDA) e grafeno estabilizado em poli(estireno sulfonato de sódio) (GPSS), designados por (PDDA-GPSS)n sendo n o número de bicamadas depositadas. Os filmes foram fabricados com a técnica de automontagem por adsorção física (LbL, do inglês Layer-by-Layer), utilizando os métodos de imersão, spray e dinâmico, disponíveis no Laboratório Finep1 da UFSCar, campus Sorocaba. Comparada a outras estratégias bottom-up empregadas na construção de filmes ultrafinos nanoestruturados, a técnica LbL é simples, barata e de fácil aplicação, além de permitir a incorporação de diferentes materiais, e não estar limitada quanto à forma e o tamanho dos substratos. Os tempos para a aplicação dos polieletrólitos por imersão e pelo método dinâmico foram estabelecidos com base nas cinéticas de crescimento de filmes (PDDA-GPSS)8. Para o método de spray os tempos foram estabelecidos inicialmente com base na literatura, e depois confirmados em ensaios de crescimento, tendo como variáveis a pressão de ar e o tempo de spray. As nanoestruturas foram caracterizadas por espectroscopia na região do ultravioleta e do visível, microscopia de força atômica, microscopia eletrônica de varredura, perfilometria e espectroscopia de impedância. Em todos os casos foi observado crescimento linear das estruturas LbL, indicando mesma quantidade de material adsorvido a cada etapa de deposição. Os filmes obtidos pelo método dinâmico indicaram maior quantidade de material agregado nas nanoestruturas, e pelo controle adequado nos parâmetros utilizados nos métodos de automontagem por adsorção física podemos realizar um ajuste fino em relação à agregação espontânea de nanofolhas de grafeno em interfaces sólidas

Carbon nanotubes (CNTs) and graphene nanoplatelets (GNPs) are attractive reinforcements for lightweight and high strength metal matrix composites due to their excellent mechanical and physical properties. The present work is an attempt towards investigating the effect of CNT and GNP reinforcements on the mechanical properties of nickel matrix composites. The CNT/Ni (dry milled) nanocomposites exhibiting a tensile yield strength of 350 MPa (about two times that of SPS processed monolithic nickel ~ 160 MPa) and an elongation to failure ~ 30%. In contrast, CNT/Ni (molecular level mixed) exhibited substantially higher tensile yield strength (~ 690 MPa) but limited ductility with an elongation to failure ~ 8%. The Ni-1vol%GNP (dry milled) nanocomposite exhibited the best balance of properties in terms of strength and ductility. The enhancement in the tensile strength (i.e. 370 MPa) and substantial ductility (~40%) of Ni-1vol%GNP nanocomposites was achieved due to the combined effects of grain refinement, homogeneous dispersion of GNPs in the nickel matrix, and well-bonded Ni-GNP interface, which effectively transfers stress across metal-GNP interface during tensile deformation. A second emphasis of this work was on the detailed 3D microstructural characterization of a new class of Ni-Ti-C based metal matrix composites, developed using the laser engineered net shaping (LENSTM) process. These composites consist of an in situ formed and homogeneously distributed titanium carbide (TiC) as well as graphite phase reinforcing the nickel matrix. 3D microstructure helps in determining true morphology and spatial distribution of TiC and graphite phase as well as the phase evolution sequence. These Ni-TiC-C composites exhibit excellent tribological properties (low COF), while maintaining a relatively high hardness.

Au cours des vingt dernières années, la diffusion inélastique de la lumière par les modes propres de vibration des nanoparticules, appelés modes de Lamb, s’est avérée être une méthode très efficace pour caractériser la taille et les propriétés mécaniques des nano-objets. La fréquence de résonance d’une nano-sphère, dans la gamme du gigahertz, est donnée, en première approximation, par le ratio de la vitesse acoustique du matériau massif et la taille du confinement. Les raffinements du modèle théorique permettent d’obtenir, à partir de ces modes de vibration, des informations essentielles sur la géométrie et l’environnement local des nano-objets. L’objectif de cette thèse est de sonder le domaine de validité du modèle de Lamb, d’analyser les différents impacts de l’environnement sur ces modes de vibration et de développer de nouvelles méthodes pour les mesurer. Plusieurs aspects de l’interaction avec le milieu extérieur peuvent ainsi être pris en considération selon le type de système étudié. D’une part, la délocalisation de l’onde acoustique dans le cas de systèmes cœur-coquille, qui est gouvernée par les impédances acoustiques respectives du cœur et de la coquille, et qui se traduit par un couplage mécanique. D’autre part, l’effet de masse inertielle induite par la présence de ligands organiques à la surface de la particule qui modifie la fréquence de résonance. La validité de ces deux approches est ainsi discutée en fonction de la configuration des objets considérés, puis ces modèles théoriques sont appliqués à des cas réels tels que des nanoparticules cœur-coquille et des nano-plaquettes de semi-conducteurs ou des agrégats métalliques colloïdaux. L’effet de masse inertielle s’avère non négligeable pour des objets de petites tailles et il est ainsi montré la faisabilité de réaliser des nano-balances ultra-sensibles capable de sonder l’environnement proche des nano-objets. Par ailleurs, dans le cas des agrégats d’or, cette approche permet de discuter les limites du modèle de Lamb, basé sur la théorie des milieux continus, sur des vibrations n’impliquant que six atomes. Ainsi, grâce à la spectroscopie Raman basses fréquences, il apparait que les résultats expérimentaux des vibrations de ces objets s’accordent à la fois avec l’approche des milieux continus en considérant l’effet de masse inertielle et aussi avec les calculs de dynamique moléculaire. Finalement, le développement expérimental d’un montage optique capable de mesurer ces modes Raman basses fréquences sur une particule unique en milieu liquide est présenté. Cette approche nécessite de localiser une particule en milieu liquide à l’aide de nano-pinces plasmoniques puis d’exalter le signal Raman basses fréquences en stimulant les modes de vibration par électrostriction. Les perspectives étant d’appliquer cette méthode à l’étude de la dynamique vibrationnelle de nano-objet unique tel que des virus ou des protéines / Over the past twenty years, inelastic light scattering by vibrational eigenmodes of nanoparticles, called Lamb modes, has proven to be an effective method for characterizing the size and mechanical properties of nano-objects. The resonant frequency of a nano-sphere, in the gigahertz range, is given, as a first approximation, by the ratio of the acoustic velocity of the bulk material and the size of confinement. The refinements of the theoretical model allow to obtain, from these eigenmodes, information on the shape and local environment of nano-objects.The objective of this thesis is to probe the domain of validity of the Lamb model, to analyze the different impacts of the environment on eigenmodes and to develop a new strategy to measure them. Several aspects of interaction with the external medium can be considered depending on the system studied. On the one hand, the delocalization of the acoustic wave in the case of core shell systems is ruled by the acoustic impedance of the core and the shell and leads to a mechanical coupling. On the other hand, the inertial mass effect induced by the presence of organic ligands on the surface of the particle modifies the resonant frequency. The validity of both approaches is discussed according to the configuration and these models are applied to real cases, such as semiconductor core shell nanoparticles and nanoplatelets, or gold colloidal clusters. The inertial mass effect is significant for small objects and it is shown the feasibility to realize ultra-sensitive nano-balance capable of probing the local environment of nano-objects. Furthermore, in the case of gold clusters, this approach makes it possible to discuss the limit of the Lamb model, based on continuum mechanics, to interpret vibrations involving only six atoms. Thanks to low frequency Raman spectroscopy, it appears that the experimental results are in good agreement with both the continuum mechanics approach, by considering the inertial mass effect, and also with density functional theory (DFT) calculations. Finally, the experimental development of an optical set-up capable of measuring low frequency Raman modes on a single nanoparticle in a liquid medium is presented. This technic requires to localize a nanoparticle in a liquid medium with plasmonic tweezers and to enhance the low frequency Raman signal by stimulating vibrational modes with electrostriction. The perspectives are to apply this method to the dynamical study of a single object such as viruses or proteins.