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 ▲]

Synthesis of uronic acid derivatives bearing a single or two alkyl chains as new surfactants

Poster (2008, September)

Synthesis of water balance data and simulation of the shrinking process of the Aral Sea.

Conference (2001)

Synthesis of well-defined poly(alkyl methacrylate)-graft-polylactone by sequential living polymerization

in Macromolecular Chemistry and Physics (1999), 200(1), 156-165

A novel combination of living polymerization reactions has been proposed for the controlled synthesis of poly(alkyl methacrylate)-graft-polylactones. This strategy relies upon the sequential living ... [more ▼]

A novel combination of living polymerization reactions has been proposed for the controlled synthesis of poly(alkyl methacrylate)-graft-polylactones. This strategy relies upon the sequential living polymerization of alkyl methacrylates and aliphatic lactones, with an intermediate chemical transformation for shifting from the first mechanism to the second one. In the first step, an alkyl methacrylate (methyl and butyl) is copolymerized with 2-trimethylsiloxyethyl methacrylate (TMSEMA). This living anionic polymerization is initiated with diphenylhexyllithium( DPHLi) in the presence of a μ-ligand, lithium chloride, in THF at - 78 °C. The trimethylsiloxy groups are then hydrolyzed with release of hydroxyl groups which are reacted with triethylaluminum in order to form a multifunctional macroinitiator of the Al alkoxide type. The second step consists of the ring opening polymerization (ROP) of aliphatic lactones (ε-caprolactone, J-valerolactone and 1,4,8-trioxaspiro[4.6]-9-undecanone (TOSUO)) with the formation of novel graft copolymers. As a result of the livingness of both the anionic and the ROP polymerization steps, the molecular weight of both the main backbone and the grafts is predictable, the apparent polydispersity is narrow ( from 1.05 to 1.30) and the grafting density can be controlled being dependent on the distribution of the hydroxyl groups within the precursor backbone. [less ▲]

Synthesis optimization of organic xerogels produced from convective air-drying of resorcinol-formaldehyde gels

in Journal of Non-Crystalline Solids (2006), 352(1), 24-34

Resorcinol-formaldehyde gels were produced at 50, 70 and 90 degrees C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied ... [more ▼]

Resorcinol-formaldehyde gels were produced at 50, 70 and 90 degrees C and with three different R/C ratios (500, 1000 and 2000). The effect of these variables combined with that of aging time was studied in order to optimize the synthesis conditions. The convective air-drying process was used, and the drying duration was studied with regard to the synthesis conditions. The aging time has no effect on the pore texture after 24 h at 90 degrees C or 48 h at 70 C, whatever the R/C value. The synthesis-aging step can be shortened by increasing the temperature. Nevertheless, the pore size tends then to decrease, especially when R/C is high, but this can be counterbalanced by increasing R/C. Moreover, bubbles often appear in the gel at high synthesis temperature, which limits the temperature to about 70 degrees C in the case of monolithic parts. At 70 degrees C and with an air velocity of 2 m/s, the elimination of 90% of the solvent requires 1 h drying when the pore size reaches 400-600 nm, 2.5 h for 50 nm wide pores and 3 h when the pore size decreases to 15-20 nm. The drying duration does not exceed 8 h in all cases and could be shortened by increasing the temperature at the end of the process. (c) 2005 Elsevier B.V. All rights reserved. [less ▲]

Synthesis, characterization and applications of pH-responsive core-shell-corona micelles in water

Doctoral thesis (2007)

ABC triblock copolymers self-organize into a wide variety of supramolecular structures in the bulk. However, their associative behavior in selective solvents has scarcely been studied. Within the search ... [more ▼]

ABC triblock copolymers self-organize into a wide variety of supramolecular structures in the bulk. However, their associative behavior in selective solvents has scarcely been studied. Within the search for new stimuli-responsive supramolecular architectures, our attention focused on a pH-responsive polystyrene-b-poly(2-vinylpyridine)-b-poly(ethylene oxide) (PS-b-P2VP-b-PEO) triblock copolymer. In addition to the synthesis of monodisperse spherical core-shell-corona (CSC) micelles, the reversibility and the cooperativity of the response to pH variations were studied, morphological transitions were induced and multi-responsive micellar gels were prepared. The micellization mechanism, the structure, the responsiveness and the internal organization of these new nanomaterials were investigated using a combination of transmission electronic microscopy, atomic force microscopy, light scattering, small-angle neutron and X-ray scattering, nuclear magnetic resonance and rheology. Finally, efforts were geared towards potential applications. The ability of PS-b-P2VP-b-PEO CSC micelles to encapsulate and release hydrophobic species was probed and gold nanoparticles were successfully synthesized within the P2VP layer of spherical and cylindrical micelles, which acted as nanoreactors. [less ▲]

Synthesis, characterization, and miscibility of caprolactone random copolymers

in Macromolecules (1986), 19(7), 1828-1838

The ring-opening polymerization and copolymerization of ε-caprolactone, ε-methyl-ε-caprolactone, β,δ-methyl-ε-caprolactone (mixed isomers), and L-lactide using aluminum isopropoxide as initiator were ... [more ▼]

The ring-opening polymerization and copolymerization of ε-caprolactone, ε-methyl-ε-caprolactone, β,δ-methyl-ε-caprolactone (mixed isomers), and L-lactide using aluminum isopropoxide as initiator were investigated. The chain propagation proceeds through a living anionic type coordinated insertion mechanism. The kinetic features of this process are reported. The experimental monomer reactivity ratios indicate that ε-caprolactone and its methyl derivatives yield random copolyesters. However, the ε-caprolactone/L-lactide pair exhibits a departure from randomness with the preferred incorporation of L-lactide units. The thermal properties of the copolymers were investigated by differential scanning calorimetry. It was found that the crystallization of ε-caprolactone units is limited, in all cases, to copolymers which are rich in this sort of unit. At the same time, the crystallization of L-lactide units was observed in copolymers with high concentrations of this comonomer. Analysis of the melting point depreasion data of the copolymers indicates that the L-lactide units are almost completely rejected from the caprolactone crystals, whereas about 50% of the ε-methyl-ε-caprolactone and δ,δ-methyl-ε-caprolactone comonomer units are incorporated into the ε-caprolactone crystals due to an obvious structural similarity. Finally, poly(ε-caprolactone-co-ε-methyl-ε-caprolactone) samples are miscible with poly(viny1 chloride) (PVC) whatever the composition of the copolymer and the composition of the blend, whereas poly(εt-caprolactone-co-L-lactide) samples are miscible with PVC uniquely for copolymer L-lactide contents equal to or smaller than 40 wt %. In all cases where miscibility was found, a negative thermodynamic interaction parameter was computed. [less ▲]