Rhodia

About: Rhodia is a based out in . It is known for research contribution in the topics: Catalysis & Alkyl. The organization has 3389 authors who have published 3448 publications receiving 58421 citations.

Hierarchically mesostructured doped CeO2 with potential for solar-cell use.

Abstract: Many properties provided by supramolecular chemistry, nanotechnology and catalysis only appear in solids exhibiting large surface areas and regular porosity at the nanometre scale In nanometre-sized particles, the ratio of the number of atoms in the surface to the number in the bulk is much larger than for micrometre-sized materials, and this can lead to novel properties Here we report the preparation of a hierarchically structured mesoporous material from nanoparticles of CeO(2) of strictly uniform size The synthesis involves self-assembly of these 5-nm CeO(2) pre-treated nanoparticles in the presence of a structure directing agent (poly(alkylene oxide) block polymer) The walls of this hexagonal structured CeO(2) material are formed from the primary nanoparticles The material possesses large pore volumes, high surface areas, and marked thermal stability, allowing it to be easily doped after synthesis whilst maintaining textural and mechanical integrity It also exhibits a photovoltaic response, which is directly derived from the nanometric particle size-normal CeO(2) does not show this response We have constructed operational organic-dye-free solar cells using nanometric ceria particles (in both mesostructured or amorphous forms) as the active component, and find efficiencies that depend on the illuminating power

Controlling droplet deposition with polymer additives

Abstract: Controlling the impact of drops onto solid surfaces is important for a wide variey of coating and deposition processes--for example, the treatment of plants with herbicides and pesticides requires precise targeting in order to meet stringent toxicological regulations. However, the outer wax-like layer of the leaves is a non-wetting substrate that causes sprayed droplets to rebound; often less than 50% of the initial spray is retained by the plant. Although the impact and subsequent retraction of non-wetting aqueous drops on a hydrophobic surface have been the subjects of extensive experimental and theoretical work, non-newtonian rheological effects have not been considered in any detail. Here we report that, by adding very small amounts of a flexible polymer to the aqueous phase, we can inhibit droplet rebound on a hydrophobic surface and markedly improve deposition without significantly altering the shear viscosity of the solutions. Our results can be understood by taking into account the non-newtonian elongational viscosity, which provides a large resistance to drop retraction after impact, thereby suppressing droplet rebound.

Highly efficient and mild copper-catalyzed N- and C-arylations with aryl bromides and iodides.

Abstract: Mild, efficient, copper-catalyzed N-arylation procedures for nitrogen heterocycles, amides, carbamates, and C-arylation procedures for malonic acid derivatives have been developed that afford high yields of arylated products with excellent selectivity. The N-arylation of imidazole with aryl bromides or iodides was found to be greatly accelerated by inexpensive, air-stable catalyst systems, combining catalytic copper salts or oxides with a set of structurally simple chelating ligands. The reaction was shown to be compatible with a broad range of aryl halides, encompassing sterically hindered, electron-poor, and electron-rich ones, providing the arylated products under particularly mild conditions (50-82 degrees C). The lower limit in ligand and catalyst loading and the scope of Ullmann-type condensations catalyzed by complexes bearing those ligands with respect to the nucleophile class have also been investigated. Chelating Schiff base Chxn-Py-Al (1c) generates a remarkably general copper catalyst for N-arylation of pyrrole, indole, 1,2,4-triazole, amides, and carbamates; and C-arylation of diethyl malonate, ethyl cyanoacetate, and malononitrile with aryl iodides under mild conditions (50-82 degrees C). The new method reported here is the most successful to date with regard to Ullmann-type arylation of some of these nucleophiles.

Carbon Nanotube Aerogels

Abstract: Aerogels are ultralight, highly porous materials typicallyfabricated by subjecting a wet-gel precursor to critical-point-drying (CPD) or lyophilization (freeze-drying) in order toremove background liquid without collapsing the network.Microscopically, aerogels are composed of tenuous networksof clustered nanoparticles, and the materials often haveunique properties, including very high strength-to-weight andsurface-area-to-volume ratios. To date most aerogels are fab-ricated from silica