One-step solvothermal synthesis of highly water-soluble, negatively charged superparamagnetic Fe3O4 colloidal nanocrystal clusters.

Highly charged hydrophilic superparamagnetic Fe3O4 colloidal nanocrystal clusters with an average diameter of 195 nm have been successfully synthesized using a modified one-step solvothermal method. Anionic polyelectrolyte poly(4-styrenesulfonic acid-co-maleic acid) sodium salt containing both sulfonate and carboxylate groups was used as the stabilizer. The clusters synthesized under different experimental conditions were characterized with transmission electron microscopy and dynamic light scattering; it was found that the size distribution and water dispersity were significantly affected by the concentration of the polyelectrolyte stabilizer and iron sources in the reaction mixtures.

Morphological and structural modulation of PbWO(4) crystals directed by dextrans.

A facile, dextran-directed solution route for the morphology- and structure-controlled synthesis of PbWO(4) crystals, such as monoclinic raspite PbWO(4) nanobelts and tetragonal stolzite PbWO(4) crystals with penniform and wheat-ear-like morphologies, has been demonstrated. Three differently charged dextrans were employed for the PbWO(4) crystallization and they turned out to be very effective in the morphological and structural modulation of PbWO(4) crystals, as evidenced by the scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD) and Raman spectroscopy characterizations. In particular, novel monoclinic raspite PbWO(4) nanobelts were produced under the direction of anionic dextran with a suitable concentration, probably due to the specific interactions between SO(4)(2-) groups from anionic dextran molecules and Pb(2+) ions from PbWO(4) crystals.

Preparation of ZnS nanorods by a liquid crystal template.

ZnS nanorods were synthesized in lamellar liquid crystals of C(12)E(4) by mixing zinc ions and thioacetamide (TAA) solution. The effects of the reactant concentration and the surfactant/water molar ratio in the liquid crystal system on the morphology and size of the ZnS particles were investigated. The prepared ZnS particles are regular nanorods having a width of about 60 nm and a length of about 80-380 nm, with a largest aspect ratio of about 6.

Controlled growth of micropatterned, oriented calcite films on a self-assembled multilayer film.

A micropatterned multilayer film, which was fabricated from layer-by-layer electrostatic self-assembly of nitrodiazoresin (NDR)/poly(acrylic acid) (PAA) followed by photolithography, was utilized as a structured template for the biomimetic mineralization of calcium carbonate. Micropatterned CaCO3 films consisting of regularly aligned calcite crystals oriented in the <104> direction were selectively deposited on the patterned NDR/PAA multilayer film.

Polymer-directed synthesis of penniform BaWO4 nanostructures in reverse micelles.

Novel penniform superstructures of BaWO4 nanowires have been successfully synthesized in catanionic reverse micelles by using a double-hydrophilic block copolymer as the directing agent. This synthetic method is very simple, mild, and controllable, and it provides a novel method for direct solution-growth of hierarchical nanostructures based on inorganic nanowires.

Synthesis of single crystal BaWO4 nanowires in catanionic reverse micelles.

High aspect-ratio, single crystal BaWO4 nanowires with diameters as small as 3.5 nm and lengths up to more than 50 microns were synthesized in catanionic reverse micelles formed by an equimolar mixture of two surfactants: undecylic acid and decylamine.