characterization of 1:1 layered uranyl silicate mineral phases ..

Scheme 4. Puckering of silicate layers in the direction shown (adapted from ref. [14]).

Synthesis of Layered Double Hydroxides Intercalated …

Hence usually PLS nanocomposites
consist of three components: polymer, layered silicate and surfactant, and the two latter components are combined
as organoclay.
There are two classes of hybrids between a polymer and nanoscopically dispersed organoclay: intercalated
nanoplatelets and exfoliated nanoplates (as shown in Fig.

92 Introduction of the synthesis of silicates 132.1 The crystal structure of silicates .

Synthesis and Characterization of Layered Metal Organic ..

Because in natural
phyllosilicate octahedral sites are usully occupied by metal atoms such as aluminum (Al), magnesium (Mg), iron
(Fe) or lithium (Li) whose formal cationic charge are less than silicon, also because of deficiency of some of the
silicon atoms, the surface of the layers is anionically charged.

One silicate layer consist of two tetrahedralsheets which are fused to one octahedral sheet.

AB - Rhodium nanoparticles were prepared by homogeneous nucleation in aqueous polymer solution and by heterogeneous nucleation on the interlayer space of layered montmorillonite and kaolinite minerals by reduction with NaBH 4 in aquatic dispersion. Rhodium particles were stabilized by polymers and by the lamellae of layered silicates. The effect of the molecular mass and the concentration of polymers on the size of the particles formed was studied using neutral polyvinylpyrrolidone, cationic poly(diallyldimethylammonium chloride), and anionic poly(sodium 4-styrenesulfonate). The effect of the concentration of the rhodium precursor was also examined; reduction of rhodium ions was controlled by X-ray photoelectron spectroscopy. Interlamellar incorporation of nanoparticles was monitored by X-ray diffraction and small-angle X-ray scattering verified by transmission electron microscopy. Average particle size fell within the range of 1-3 nm, depending on the stabilization method used and the concentration of precursor rhodium ions.

Among them,hectorite and montmorillonite are the most commonly used smectite-type layered silicates for the preparation ofnanocomposites.


Applied Clay Science - Journal - Elsevier

Steel et al.[14] postulated that surfactant molecules assembled directly into the hexagonal LC phase upon addition of the silicate species, based on 14N NMR spectroscopy. The silicates were organized into layers, with rows of the cylindrical rods intercalated between the layers (Scheme 4). Aging the

General & Introductory Chemistry

The lamellar-to-hexagonal phase motif also appeared in materials called FSM prepared from the intercalation of the ammonium surfactant in kanemite, a type of hydrated sodium silicate composed of single-layered silica sheets.[17] After the surfactants were ion-exchanged into the layered structure, the silicate sheets were thought to fold around the surfactants and condense into a hexagonal mesostructure (Scheme 6). The

Program | 6th World Congress and Expo on …

Davis and co-workers[13] found that the hexagonal LC phase did not develop during MCM-41 synthesis, based on in situ 14N NMR spectroscopy. They proposed that, under the synthesis conditions reported by Mobil, the formation of MCM-41 began with the deposition of two to three monolayers of silicate precursor onto isolated surfactant micellar rods (Scheme 3). The silicate-encapsulated rods were randomly

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In EPR and NMR studies of the surfactant layer that compatibilizes the silicate and thepolymer, we found that the iron content in these natural clays is detrimental, as it broadens spec-tra and shortens relaxation times.

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The problem was overcome by using as a layered silicate iron-freeand structurally well defined magadiite, which was synthesized by a hydrothermal method.