Physicochemical investigation of acrylamide solubilization in sodium bis(2-ethylhexyl)sulfosuccinate and lecithin reversed micelles.

2003

The state of acrylamide confined within dry sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and lecithin reversed micelles dispersed in CCl4 has been investigated by FTIR and H-1 NMR spectroscopy. Measurements have been performed at 25 degreesC as a function of the acrylamide-to-surfactant molar ratio (R) at a fixed surfactant concentration (0.1 mol kg(-1)). The analysis of experimental data, corroborated by the results of SAXS measurements, is consistent with the hypothesis that acrylamide is quite uniformly distributed among reversed micelles mainly located in proximity to the surfactant head-group region and that its presence induces significant unidimensional growth of micellar aggregates.…

Synthesis and physico-chemical characterization of gold nanoparticles softly coated by AOT

2006

Size-controlled gold nanoparticles/surfactant stable systems were prepared by the combined action of the solvated metal atom dispersion (SMAD) technique and confinement in anhydrous sodium bis(2-ethylhexyl)sulfosuccinate (AOT) micellar solution. From liquid samples, by evaporation of the organic solvent, solid gold nanoparticle-surfactant liquid crystals composites were obtained. Sample characterization was performed by X-ray diffraction (SAXS and WAXS), XPS spectroscopy and UV-vis-NIR spectroscopy. All experimental data consistently revealed the coexistence of two gold nanoparticle size populations: bigger nanoparticles (size 20-50 angstrom) and smaller ones (size of few angstrom). The two…

Physicochemical investigation of surfactant-coated gold nanoparticles synthesized in the confined space of dry reversed micelles

2006

Abstract Gold nanoparticle/surfactant composites have been synthesized by a novel reduction reaction in the confined space of dry sodium bis(2- ethylhexyl)sulfosuccinate (AOT) or lecithin reversed micelles dispersed in n-heptane and cyclohexane, respectively. The reaction was carried out by adding an opportune amount of anhydrous hydrazine/tetrahydrofuran solution to a suspension of HAuCl4-containing dry reversed micelles dispersed in organic solvent. UV–vis investigation ascertained the formation of stable metal gold nanoparticles and the analysis of FT-IR spectra highlighted the formation of an oriented surfactant monolayer at the nanoparticle surface. Simple evaporation under vacuum of t…

Physicochemical investigation of cobalt?iron cyanide nanoparticles synthesized by a novel solid?solid reaction in confined space

2004

Cobalt–iron cyanide (Cox[Fe(CN)6]) nanoparticles have been synthesized by a novel solid–solid reaction in the confined space of dry sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reversed micelles dispersed in n-heptane. The reaction has been carried out by mixing two dry AOT/n-heptane solutions containing CoCl2 and K4Fe(CN)6 or K3Fe(CN)6 nanoparticles in the micellar core, respectively. By UV-Vis spectroscopy it was ascertained that, after the mixing process, the formation of stable nanoparticles is fast and complete. Microcalorimetric measurements of the thermal effect due to the Cox[Fe(CN)6] nanoparticle formation allowed the determination of the stoichiometric ratio (x) and of the molar e…

Non-conventional Ce:YAG nanostructures via urea complexes

2019

AbstractCe:YAG nanostructures (Ce:YAG = Cerium in Yttrium Aluminium Garnet), easy to control and shape, have been prepared via templating approach using natural and synthetic materials (i.e. paper, cotton wool and glass wool) previously soaked with a gel-like metals precursor and then thermally treated to achieve the wished morphology. The final material, otherwise difficult to process, can be easily moulded, it is lightweight, portable and forms, at the nanoscale, homogeneous layers of interconnected but not agglomerated nanoparticles (15 ± 5 nm). Using the same synthetic route, called Urea-Glass-Route, but in absence of a template, extremely pure Ce:YAG nanoparticle (45 ± 5 nm) can be als…

Multimetallic Oxynitrides Nanoparticles for a New Generation of Photocatalysts

2019

A versatile synthetic strategy for the preparation of multimetallic oxynitrides has been designed and here exemplarily discussed considering the preparation of nanoscaled zinc-gallium oxynitrides and zinc-gallium-indium oxynitrides, two important photocatalysts of new generation, which proved to be active in key energy related processes from pollutant decomposition to overall water splitting. The synthesis presented here allows the preparation of small nanoparticles (less than 20 nm in average diameter), well-defined in size and shape, yet highly crystalline and with the highest surface area reported so far (up to 80 m2  g-1 ). X-ray diffraction studies show that the final material is not a…

Non-conventional Fe3C-based nanostructures

2011

Novel Fe3C-based nanostructures with an inner layered structure have been synthesized by a simple medium-temperature (T = 700 °C) process based on carbothermal reduction. In this process, the iron precursor reacts with a selected nitrogen rich carbon source (namely, 4,5-dicyanoimidazole) to form wrapped nano-sheets of Fe3C@C(N). The nanosheets are composed of 5 nm crystalline Fe3C nanoparticles, which are integrated into a nitrogen-doped carbon phase giving rise to the wrapped morphology. By variation of reaction parameters (such as initial concentration, temperature, reaction time), the typical accompanying side products of iron carbide such as metallic iron and amorphous carbon can be kep…

H-NMR and FT-IR study of the state of melatonin confined in membrane models: location and interactions of melatonin in water free lecithin and AOT re…

2004

The state of melatonin confined either in dry lecithin or bis(2-ethylhexyl) sulfosuccinate sodium salt (AOT) reversed micelles has been investigated by H-NMR and FT-IR spectroscopies as a function of the melatonin to surfactant molar ratio (R). The analysis of experimental results leads to hypothesize that, independently of R and the surfactant nature and as a consequence of anisotropic melatonin/surfactant interactions, melatonin is totally solubilized in reversed micelles and mainly located by opportune orientation in the nanodomain constituted by the surfactant head groups. The absence of significant spectral changes related to the protons linked to the first carbon atoms of surfactant a…

Influence of cerium content and heat treatment on Ce:YAG@glass wool nanostructures

2019

The paper reports the influence of cerium content and heat treatment on composition, structural features and optical properties of nanostructures constituted by a layer of Ce:YAG nanoparticles on glass wool (Ce:YAG@GW). The Ce:YAG@GW nanostructures were obtained embedding the glass wool (GW) in a gel-like precursor and calcining at 800 and 900 °C. Gel-like precursor of urea glass route (UGR) method has been used to prepare both nanostructures and Ce:YAG nanoparticles prepared as references. Structural properties were investigated by using X-ray diffraction (XRD) and infrared spectroscopy (IR). Results showed that the composition of the final products strongly depends both on the cerium cont…

Synthesis and physico-chemical characterization of gold nanoparticles

2004