Synthesis of pyerene containing polymers and noncovalent side-wall functionlization of multi-walled carbon nanotubes

Poster (2004, May 27)

Synthesis of regional product activities JRA4-JRA9

Conference (2010, April 01)

Synthesis of SiO2 xerogels and Pd/SiO2 cogelled xerogel catalysts from silylated acetylacetonate ligand

in Journal of Non-Crystalline Solids (2004), 343(1-3), 109-120

SiO2 xerogels and Pd/SiO2 cogelled xerogel catalysts have been prepared in a mixture of tetrahydrofurane (THF) and ethanol containing tetraethoxysilane (TEOS), and an aqueous ammonia solution of 0.18 mol ... [more ▼]

SiO2 xerogels and Pd/SiO2 cogelled xerogel catalysts have been prepared in a mixture of tetrahydrofurane (THF) and ethanol containing tetraethoxysilane (TEOS), and an aqueous ammonia solution of 0.18 mol/l, from synthesized new silylated acetylacetonate ligands, respectively, 3-[3-(trimethoxysilyl)propyl]-2,4-pentanedione (MS-acac-H), 2,2,6,6-tetramethyl-4-[3-(trimethoxysilyl)propyl]-3,5-heptanedione (MS-dPvM), and 1,3-diphenyl-2-[3-(trimethoxysilyl)propyl]-1,3-propanedione (MS-dBzM), able to form a chelate with a metal ion such as Pd2+. All samples form homogeneous colored gels. The resulting catalysts are composed of palladium crystallites with a diameter of about 3.5 nm, located inside primary silica particles exhibiting a monodisperse microporous distribution as well as large palladium particles from 20 to 50 nm, situated outside the silica aggregates. The silylated organic ligand has a strong influence on the textural properties of xerogels and catalysts, both before and after calcination and reduction steps. Changing the nature of the silylated ligand permits tailoring textural properties such as pore volume, pore size and surface area. Although small palladium crystallites are located inside the silica particles, their complete accessibility, via the micropore network, has been shown. 1,2-Dichloroethane hydrodechlorination over Pd/SiO2 catalysts mainly produces ethane and the reaction rate increases linearly with palladium dispersion. Hydrodechlorination over Pd/SiO2 cogelled xerogel catalysts is a structure insensitive reaction compared to the ensemble size concept. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

SYNTHESIS OF SIO2-TIO2 XEROGELS BY SOL-GEL PROCESS

in Journal of Sol-Gel Science and Technology (1995), 4(3), 179-185

A new method to synthesize SiO2-TiO2 gels by sol-gel process has been developed. This technique uses tetraisopropylorthotitanate [Ti(O'Pr)(4)] and tetraethylorthosilicate [TEOS]: they are mixed in the ... [more ▼]

A new method to synthesize SiO2-TiO2 gels by sol-gel process has been developed. This technique uses tetraisopropylorthotitanate [Ti(O'Pr)(4)] and tetraethylorthosilicate [TEOS]: they are mixed in the same solvent and then directly hydrolysed. This one-step reaction is possible because of the use of 2-methoxyethanol, a protic polar solvent. This alcohol plays two different specific roles: it acts as a solvent as well as a stabilizer of titanium alkoxide towards the hydrolysis-precipitation reaction. So, by an accurate adjustment of the quantity of methoxyethanol in the mixture, we can control the reactivity of the titanium precursor. Monolithic and transparent xerogels were obtained whatever the composition. Three monolithic SiO2-TiO2 gels containing 20, 50 and 75 mol% of TiO2 were prepared and studied in details. By using the TG-DSC analysis, we can follow the evolution of the loss of water and organic residues. The structural evolution of gels during calcination is characterized by IR spectroscopy and X-Ray diffraction. [less ▲]

Synthesis of stilbenoids via the Suzuki-Miyaura reaction catalysed by palladium N-heterocyclic carbene complexes

in Journal of Molecular Catalysis A: Chemical (2006), 257(1-2), 158-166

The Suzuki-Miyaura reaction of aryl halides with trans-2-phenylvinylboronic acid using a series of related in situ generated N-heterocyclic carbene palladium(II) complexes was studied in order to evaluate ... [more ▼]

The Suzuki-Miyaura reaction of aryl halides with trans-2-phenylvinylboronic acid using a series of related in situ generated N-heterocyclic carbene palladium(II) complexes was studied in order to evaluate the effect of ligand structure and electronics on the catalytic activity and to investigate the nature of the catalyst species. The nature of the substituents of the carbene ligand was found to be critical. Specifically, the presence of alkyl groups on the ortho positions of the phenyl substituents was a requisite for obtaining the most efficient catalyst systems. (c) 2006 Elsevier B.V. All rights reserved. [less ▲]

Synthesis of tadpole-shaped copolyesters based on living macrocyclic poly(epsilon-caprolactone)

in Polymer (2006), 47(26), 8406-8413

Synthesis of an asymmetric tadpole-shaped aliphatic copolyester consisting of a poly(epsilon-caprolactone) ring and two poly(L-lactide) tails was reported for the first time. First, a high molecular ... [more ▼]

Synthesis of an asymmetric tadpole-shaped aliphatic copolyester consisting of a poly(epsilon-caprolactone) ring and two poly(L-lactide) tails was reported for the first time. First, a high molecular weight cyclic PCL macroinitiator (Mn = 31,000) was prepared by intramolecular photocross-linking of "living" chains. Polymerization of L-lactide was resumed by the tin dialkoxide containing macrocycles, thus making the targeted tadpole-shaped copolyester available. A preliminary investigation of the crystallization of these copolyesters was carried out by differential scanning calorimetry and polarized optical microscopy. [less ▲]

Synthesis of Tetraalkyl(Pyrrolidine-2,2-diyl)bisphosphonates and 2,2-Bis(diethoxyphosphoryl)-3,4-dihydro-2H-pyrrole 1-Oxide; ESR Study of Derived Nitroxides

in Journal of Organic Chemistry (1998), 63(24), 9095-9099

Synthesis of Tetraalkyl (Pyrrolidine-2,2-diyl)bisphosphonates and 2,2-Bis(diethoxyphosphoryl)-3,4-dihydro-2Hpyrrole 1-Oxide; ESR Study of Derived Nitroxides

Synthesis of thermo-responsive poly(N-vinylcaprolactam)-containing block copolymers by cobalt-mediated radical polymerization

in Journal of Polymer Science. Part A-1, Polymer Chemistry (2012), 50(2), 400-408

Thermo-responsive block copolymers based on poly(N-vinylcaprolactam) (PNVCL) have been prepared by cobalt-mediated radical polymerization (CMRP) for the first time. The homopolymerization of NVCL was ... [more ▼]

Thermo-responsive block copolymers based on poly(N-vinylcaprolactam) (PNVCL) have been prepared by cobalt-mediated radical polymerization (CMRP) for the first time. The homopolymerization of NVCL was controlled by bis(acetylacetonato)cobalt(II) and a molecular weight as high as 46,000 g/mol could be reached with a low polydispersity. The polymerization of NVCL was also initiated from a poly(vinyl acetate)-Co(acac)2 (PVAc-Co(acac)2) macroinitiator to yield well-defined PVAc-b-PNVCL block copolymers with a low polydispersity (Mw/Mn = 1.1) up to high molecular weights (Mn = 87,000 g/mol), which constitutes a significant improvement over other techniques. The amphiphilic PVAc-b-PNVCL copolymers were hydrolyzed into unprecedented double hydrophilic poly(vinyl alcohol)-b-PNVCL (PVOH-b-PNVCL) copolymers and their temperature-dependent solution behavior was studied by turbidimetry and dynamic light scattering. Finally, the so-called cobalt-mediated radical coupling (CMRC) reaction was implemented to PVAc-b-PNVCL-Co(acac)2 precursors to yield novel PVAc-b-PNVCL-b-PVAc symmetrical triblock copolymers. [less ▲]

Synthesis of titanium dioxide nanoparticles by reactive DC magnetron sputtering

in Thin Solid Films (2009), 518

Nanometer-sized titanium dioxide (TiO2) particles were prepared on carbon substrates by reactive direct-current magnetron sputtering. By performing measurements with high resolution electron microscopes ... [more ▼]

Nanometer-sized titanium dioxide (TiO2) particles were prepared on carbon substrates by reactive direct-current magnetron sputtering. By performing measurements with high resolution electron microscopes, the mean nanoparticle diameter and the coverage fraction of the substrate by the nanoparticles (NPs) were measured at 19 nm and 30%, respectively. Moreover, electron diffraction analysis showed that the TiO2 NPs' crystalline structure on the carbon substrate was a mixture of anatase and rutile. Finally,we provided information on the TiO2 initial growth stage: crystalline NPs were formed after deposition of amorphous nanoparticles on the substrate and heating. [less ▲]

Synthesis of transition metal-doped carbon xerogels by solubilization of metal salts in resorcinol-formaldehyde aqueous solution

in Carbon (2004), 42(15), 3217-3227

The pore texture of carbon materials obtained from evaporative drying and pyrolysis of resorcinol-formaldehyde aqueous gels is controlled by the initial pH of the precursors solution. In order to produce ... [more ▼]

The pore texture of carbon materials obtained from evaporative drying and pyrolysis of resorcinol-formaldehyde aqueous gels is controlled by the initial pH of the precursors solution. In order to produce transition metal-containing carbons with tailored texture, various metallic salts were dissolved in the precursors solution. When necessary, a complexing agent (HEDTA or DTPA) was added to render the metal ions soluble. Ni, Fe and I'd loaded carbon xerogels were synthesized and their pore texture was studied after evaporative drying and after pyrolysis. The carbon texture was also studied with regard to the nature of the metal and the amount of complexing agent. The solubilization of transition metal salts in the resorcinol-formaldehyde aqueous solution does not prevent the texture regulation, even though this texture control is influenced: the limits of the pH interval leading to micro mesoporous carbon materials can slightly differ when a metal salt and/or a complexing agent are added. The pH range shift depends mainly on the amount and nature of the complexing agent, but also slightly on the nature of the metal ion. Nevertheless, the metal particles obtained are rather big (diameter > 15 nm). For catalytic applications, the metal dispersion must be enhanced, especially in the case of expensive metals. (C) 2004 Elsevier Ltd. All rights reserved. [less ▲]