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Functionalized reverse micelles are used to control the size of silver sulfide, Ag2S, nanosized particles. The size of the crystallites varies linearly with the water content from 2 to 10 nm. The particles have been coated by dodecanethiol and extracted from micelles. The size of the particles dispersed in heptane has bene determined by SAXS experiments and compared to those obtained by TEM. A good...
The photoinduced electron transfer reactions from nanosized CdS particles synthesized in micelles of cadmium lauryl sulphate and sodium lauryl sulphate to various dialkyl viologens is measured for a molar ratio of cadmium to sulphide ions equal to 2. — The yield of the reduced viologens obtained by CdS irradiations is miximum in the case of C1 viologen, which decreases gradually with increase...
By means of ion exchange chromatography, a new surfactant was synthesized. Its purity and characteristics, molecular and micellar, were investigated. The originality of this surfactant lies in its counterion, which is a polymerizable group. The polymerization of such direct micellar solution did not lead to precipitation. The use of different techniques like light scattering, NMR, fluorescence spectroscopy,...
We report changes in the percolation threshold of AOT water droplets by solubilizing cytochrome c, a water-soluble protein. The change of the critical percolation factors (volume fraction, temperature, water content) is attributed to the increase in the attractive interactions between droplets by solubilizing cytochrome c in water droplets. The critical exponents determined from percolation theories...
Structural studies of reverse micelles containing native and modified α-chymotrypsin are reported. Reverse micelles were used to increase the hydrophobic character of α-chymotrypsin. Three fluorene derivatives were linked to α-chymotrypsin. Determination of the percolation threshold of reverse micellar solution containing native and modified α-chymotrypsin, by conductivity measurements, was performed...
In this paper, preliminary results show the formation of cytochrome c monolayer. At low pressure, cytochrome c molecules remain at the interface, whereas at high pressure part of the cytochrome c is redissolved into the bulk phase. A surfactant monolayer formed at the air/water interface is strongly disturbed by injecting cytochrome c into the subphase. These changes are mainly attributed to the adsorption...
Small angle x-ray scattering (SAXS) measurements were carried out on w/o microemulsions containing two different enzymatic systems: trypsin or lipase. The results were compared to SAXS measurements in the absence of proteins. When relatively small reverse micelles were used, the presence of enzyme induced a decrease of the aqueous core radius. For larger droplets the presence of the biomolecules did...
Synthesis of hydrophobic ribonuclease and α-chymotrypsin is performed in AOT reverse micelles in order to covalently bind hydrophobic molecules on to the enzymes’ surface. Enzyme characterization is described using high performance liquid chromatography and electrophoresis. Location of enzyme derivatives within reverse micelles is determined using fluorescence experiments. These indicate that modified...
The AO:T water/oil microemulsions exhibit a percolation process which leads to the formation of aggregates when temperature or water droplets concentration increase. In the presence of cytochrome c, this aggregation process is more efficient. In order to know the influence of this protein on the structure of the aggregates so formed, we report structural studies by SAXS. The reuslts show that the...
Functionalized reverse micelles are used to control the size of the CdS semiconductor particles. We show, in dilute solution, that the use of mixed sodium-cadmium AOT reverse micelles favors the formation of monodispersed particles. By increasing the water content, the size of the particle increases, and it maintains a high monodispersity. The increase of the water pool concentration and the amount...
Divalent (2-ethyl hexyl) sulfosuccinate surfactant is used to form water in oil aggregates. By increasing the water content pronounced structural changes are observed. At low water content spherical droplets are formed. By increasing the water content, cylindrical aggregates are formed. The maximum amount of water solubilized using divalent surfactants is relatively low (the limit value of the ratio...
Functionalized surfactant micelles are used to prepare small metallic copper particles. At low water content, small metallic particles are formed. By increasing the water content, passivation takes place.
The synthesis of a new polymerizable surfactant forming reverse micelles has been performed. The didecyldimethylammonium methacrylate is soluble in aromatic solvents and, by water addition, the solutions remain clear, stable over several months, and low conducting. Structural studies of these microemulsions have been performed by small-angle x-ray and dynamic quasi elastic light scattering. These...
Structural comparison of AOT reverse micelles in the presence and in the absence of native and modified ribonuclease is reported. The intermicellar potential of filled and unfilled micelles determined by SAXS and the percolation threshold are found unchanged.
In this paper it is shown that the solubilization of native and chemically modified cytochrome c differing by their number of elementary charge in reverse micellar solution induces changes in the percolation onset and the intermicellar interaction potential.
Functionalized reverse micelles are used to control the size and the polydispersity of the metallic and semiconductor particles. The size of the particles can be controlled, either by the amount of water solubilized in the droplets, or by the solvent used to form reverse micelles, or by adding macrocyle molecules.
In this short note, we show the formation of colloidal copper mettalic particles synthesized in situ in mixed reverse micelles. From the differences in the absorption spectra it is deduced that the size of the particles decreases with the water content.
In this paper, various ways to make nanocrystals are presented. It is possible, by using colloidal self-assemblies as nanoreactors, to produce a large variety of nanoparticles, semiconductors, metals, oxides and alloys The limitations in using these colloidal solutions to produce nanomaterials are pointed out.
Longitudinal acoustic phonons with few-GHz frequency were detected in three-dimensional supracrystals [1] (with face-center cubic lattice) of 7-nm cobalt nanocrystal spheres [2]. In analogy with usual atomic crystals, where longitudinal acoustic phonons propagate with the speed of sound through coherent movements of atoms of the lattice out of their equilibrium positions [3], in these supracrystals...
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