Search results for "colloid"
showing 10 items of 1288 documents
CsPbX3/SiOx (X = Cl, Br, I) monoliths prepared via a novel sol-gel route starting from Cs4PbX6 nanocrystals
2019
We developed a facile synthesis of nanocomposite powders of CsPbX3 nanocrystals (NCs) embedded in silica. The synthesis starts from colloidal Cs4PbX6 NCs that are mixed with tetraethyl orthosilicate in the presence of nitric acid, which triggers the sol-gel reaction yielding the formation of SiOx and the conversion of starting NCs into CsPbX3 ones. The overall reaction delivers CsPbX3 NCs encased in a silica matrix. The resulting CsPbX3/SiOx nano-composite powders exhibited enhanced moisture and thermal stability in air. Also, when mixing different CsPbX3/SiOx samples having diverse anion compositions, no interparticle anion exchange processes were observed, which is a further indication th…
Ag and Au/DNQ-novolac nanocomposites patternable by ultraviolet lithography: a fast route to plasmonic sensor microfabrication
2010
In this work we report on a method to synthesize Ag–Au nanoparticles/polymer nanocomposite patterns by UV lithography. The photoresists are based on DNQ-novolac as the polymer matrix, and Ag(I) and Au(III) salts as the nanoparticle precursors. After UV lithography, silver and gold nanoparticles are in situ synthesized inside the polymer patterns during a post bake. The resulting structured nanocomposite shows a characteristic absorbance spectrum related to the plasmon frequency of the synthesized noble metal NPs. This method represents a fast, simple and low-cost approach to the formation of extended polymer patterns with embedded silver or gold NPs. Moreover, it is a mechanism to position …
Thermal stability of Au–TiO2 nanocomposite films prepared by direct liquid injection CVD
2015
Abstract Nanocomposite films composed of gold nanoparticles (AuNPs) embedded in a TiO 2 matrix have been prepared by direct liquid injection chemical vapor deposition process, using preformed nanoparticles and titanium isopropoxide as precursors. The spherical AuNPs about 4.1 nm in diameter were synthesized by using gold (III) chloride trihydrate and stabilized by thiol ligands. The depositions were carried out by performing at first oxide deposition, then gold nanoparticle one and capping with oxide. The morphology, structure; the chemical state and optical properties of nanocomposite films were characterized by scanning electron microscopy, Raman, X-ray photoelectron and UV–Vis absorption…
Atomically Precise Gold Nanoclusters: Towards an Optimal Biocompatible System from a Theoretical-Experimental Strategy.
2021
Potential biomedical applications of gold nanoparticles have increasingly been reported with great promise for diagnosis and therapy of several diseases. However, for such a versatile nanomaterial, the advantages and potential health risks need to be addressed carefully, as the available information about their toxicity is limited and inconsistent. Atomically precise gold nanoclusters (AuNCs) have emerged to overcome this challenge due to their unique features, such as superior stability, excellent biocompatibility, and efficient renal clearance. Remarkably, the elucidation of their structural and physicochemical properties provided by theory-experiment investigations offers exciting opport…
Dynamics of paramagnetic nanostructured rods under rotating field
2011
International audience; The dynamical rotational behavior of magnetic nanostructured rods based on the auto-association of maghemite nanoparticles and block-copolymers is probed by optical microscopy under rotating fields i n a s imple l iquid. The reorientation of the rods by a field rotated by 90° is first studied. The measured relaxation is characteristic of param-agnetic objects. Under a stationnary rotating field, a synchronous rotational regime is observed at low field frequency. Above a frequency threshold which scales as H^2 , the dynamics becomes asynchronous with back-and-forth rotations. These behaviors are well predicted by the presented model.
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…
Synthesis and physico-chemical characterization of Au/TiO2 nanostructures formed by novel "cold" and "hot" nanosoldering of Au and TiO2 nanoparticles…
2011
Abstract A novel approach to synthesize Au/TiO2 nanostructures with interesting optical properties is presented and discussed. It is based on the nanoparticle “cold” or “hot” nanosoldering occurring when two water suspensions of Au and TiO2 nanoparticles are merely mixed at room temperature or laser irradiated after mixing. Thanks to the high fraction and mutual reactivity of surface species, immediately after the mixing process, the encounters between Au and TiO2 nanoparticles in liquid phase are enough for “cold” nanosoldering of gold nanoparticles onto TiO2 nanoparticles to occur. The optical characterizations show that this fast process (timescale less than 1 min) is followed by a slowe…
Correction: Seedless assembly of colloidal crystals by inverted micro-fluidic pumping.
2018
Correction for ‘Seedless assembly of colloidal crystals by inverted micro-fluidic pumping’ by Ran Niu et al., Soft Matter, 2018, 14, 3435–3442.
Exploiting the Colloidal Stability and Solubilization Ability of Clay Nanotubes/Ionic Surfactant Hybrid Nanomaterials
2012
Halloysite clay nanotubes are functionalized by exploiting the different charges between the inner positive and the outer negative surfaces; accordingly, a selective adsorption is pursued by employing anionic and cationic surfactants. The obtained hybrid materials dispersed in aqueous phase are studied from the physicochemical viewpoint to investigate the colloidal stability that is a crucial parameter for applications. It is demonstrated that the adsorption of anionic surfactant into the HNTs lumen increases the net negative charge of the nanotubes enhancing the electrostatic repulsions and consequently the dispersion stability. The solubilization capability of these functionalized nanotub…
Crystallization kinetics of colloidal model suspensions: recent achievements and new perspectives
2014
Colloidal model systems allow studying crystallization kinetics under fairly ideal conditions with rather well characterized pair interactions and minimized external influences. In complementary approaches therefore experiment, analytic theory and simulation have been employed to study colloidal solidification in great detail. These studies were based on advanced optical methods, careful system characterization and sophisticated numerical methods. Both the effects of the type, strength and range of the pair-interaction between the colloidal particles and those of the colloid-specific polydispersity were addressed in a quantitative way. Key parameters of crystallization were derived and comp…