Pessac, France
Pessac, France

Time filter

Source Type

Benhadjala W.,French National Center for Scientific Research | Benhadjala W.,CEA Grenoble | Gravoueille M.,Électricité de France | Bord-Majek I.,French National Center for Scientific Research | And 8 more authors.
Applied Physics Letters | Year: 2015

Extensive research is being conducted on the development of inorganic/organic nanocomposites for a wide variety of applications in microelectronics, biotechnologies, photonics, adhesives, or optical coatings. High filler contents are usually required to fully optimize the nanocomposites properties. However, numerous studies demonstrated that traditional composite viscosity increases with increasing the filler concentration reducing therefore significantly the material processability. In this work, we synthesized inorganic/organic core-shell nanocomposites with different shell thicknesses. By reducing the shell thickness while maintaining a constant core size, the nanoparticle molecular mass decreases but the nanocomposite filler fraction is correlatively increased. We performed viscosity measurements, which clearly highlighted that intrinsic viscosity of hybrid nanoparticles decreases as the molecular mass decreases, and thus, as the filler fraction increases, as opposed to Einstein predictions about the viscosity of traditional inorganic/polymer two-phase mixtures. This exceptional behavior, modeled by Mark-Houwink-Sakurada equation, proves to be a significant breakthrough for the development of industrializable nanocomposites with high filler contents. © 2015 AIP Publishing LLC.

Agency: Cordis | Branch: FP7 | Program: CP-FP | Phase: NMP-2009-1.3-1 | Award Amount: 3.30M | Year: 2010

The project NANOPOLYTOX will evaluate the toxicological impact of nanomaterials included in polymer nanocomposites, highly used in various industrial sectors, during their life cycle. The toxicological profile will be correlated with the changes in the physical and chemical properties of the nanomaterials during the artificial aging/weathering process of the polymeric nanocomposites. Raw nanomaterials and extracted nanomaterials will be characterized at different stages of their life cycle and their toxicity profiles will be obtained via in vitro and in vivo toxicity studies. The results from the in vivo studies will be used for the evaluation of the biological and environmental fate of nanomaterials. All the data generated during the project (physical, chemical and toxicological data) will be considered for the development of the novel LCIA methodology to apply to nanomaterials. These studies will also be taken into account for the selection of adequate digestion and extraction methods to separate the nanomaterials from the polymeric matrices. Moreover, optimization of these methods will facilitate the development of recycling techniques that will be applied in the end-stage of polymer nanocomposites. Disposal of the extracted toxic and/or innocuous nanomaterials will be carried out by mechanical and chemical recycling techniques. The chemical recycling technique will be based on a new separation method consisting of nanofiber filters to separate efficiently the raw nanomaterials from the polymeric matrices and re-use them in new applications. Finally, the nanofiber filters containing toxic nanomaterials will be immobilized in xerogel matrices by sol-gel processes and sintering.

Gaud V.,Polyrise SAS | Rouge F.,Polyrise SAS | Gnanou Y.,CNRS Organic Polymer Chemistry Laboratory | Gnanou Y.,CNRS Institute of Molecular Sciences | Desvergne J.-P.,CNRS Institute of Molecular Sciences
Reactive and Functional Polymers | Year: 2012

New photoactive polymerizable monomers were synthesized in order to photomodulate the mechanical properties of photocurable materials. These monomers are end-capped by at least two polymerizable units (using irradiation wavelength λ1) connected by a spacer including at least one photocleavable unit (irradiation wavelength λ2 ≠ λ1) i.e. aryltriazene or 2-nitrobenzyl core. The photochemical behaviour of these systems was studied in solution and in resin formulations. Their ability to promote the hardening and crosslinking of a curable resin at λ1, then the subsequent degradation or modification of crosslinked resins under an actinic light (λ2) was evaluated by DMA for formulations including these new monomers. These new monomers were shown, in resin formulation, to readily rigidify the material upon λ1 irradiation and for most of them the subsequent photolysis of their internal linkers at λ2 irradiation was followed by a decrease of the hardness at low temperature (-20 °C). For one of them (compound 6) λ2 illumination at room temperature provoked the decrease of the mechanical properties of the solid material making it of interest for dental applications. © 2012 Elsevier Ltd. All rights reserved.

Benhadjala W.,French National Center for Scientific Research | Bord-Majek I.,French National Center for Scientific Research | Bechou L.,French National Center for Scientific Research | Suhir E.,University of California at Santa Cruz | And 4 more authors.
Proceedings - Electronic Components and Technology Conference | Year: 2013

In our recent publication we have demonstrated that BaTiO 3/hyperbranched polyester/methacrylate hybrid nano-particles, with a filler fraction of 41 wt.% first dissolved in 2-butoxyethanol and crosslinked during 3 hours (at 125°C), exhibited highly promising dielectric constant as high as 85 at 1kHz. On the other hand, when the same hybrid nanoparticles have been diluted in methyl methacrylate (MMA) and then cured for 12 hours at the same temperature the permittivity of the material decreased significantly and reached 5 at 1 kHz. In the present work we have studied how processing factors, such as the employed diluent and crosslinking duration, affect the dielectric properties of the core-shell nanoparticles. In our first set of experiments we have studied the electrical properties of capacitors fabricated using the solution of hybrid nanoparticles diluted in 2-butoxyethanol. Curing has been monitored for 13 hours at 125°C. We have determined that the duration of thermal curing has a significant effect on dielectric properties of BaTiO 3/hyperbranched polyester/methacrylate nanocomposites. In the second set of experiments the diluent influence on the properties of hybrid nanoparticles was investigated. As had been expected, dielectric constants of particles diluted in MMA were lower than those of hybrid particles diluted in 2-butoxyethanol. The origin of this phenomenon was determined by comparing the chemical behavior of the diluents under thermal curing. 2-butoxyethanol characterized by a boiling point of 170°C was evaporated during the thermal curing process. Despite the boiling point of 100°C, MMA polymerizationis predominant upon evaporation, and leads to the decrease in the initial filler fraction. This explanation has been validated by measuring the weight losses of samples oven-dried at 125 °C for 13 hours. We discuss in detail the experimental data and results, as well as their use in understanding the basic physical mechanisms underlying the observed electrical behaviors of hybrid nanoparticles. © 2013 IEEE.

Benhadjala W.,French National Center for Scientific Research | Bord I.,French National Center for Scientific Research | Bechou L.,French National Center for Scientific Research | Suhir E.,University of California at Santa Cruz | And 3 more authors.
Proceedings - Electronic Components and Technology Conference | Year: 2012

Thin capacitors using new hybrid nanoparticles as dielectric material have been successfully fabricated by a roll-to-roll process. The nanoparticles with a BaTiO 3 core and a hyperbranched polyester shell have been synthesized at a filler fraction of approximately 41 wt%. For the first time, dielectric properties of monolithic nanocomposite-based capacitors have been investigated over an extremely wide frequency range from 10Hz to 1.2GHz. A dedicated test circuit has been designed and manufactured to characterize the capacitors at high frequencies directly on the sample. It has been demonstrated that promising resonance frequencies above 600MHz and dielectric constants needed for the existing commercial products can be achieved on the basis of the employed nano-technology. We conclude that hybrid BaTiO 3/ hyperbranched-polyester nanoparticles have the potential to outperform the existing systems and are suitable for the use as an effective dielectric in embedded radiofrequency (RF) capacitors. © 2012 IEEE.

Benhadjala W.,French National Center for Scientific Research | Bord-Majek I.,French National Center for Scientific Research | Bechou L.,French National Center for Scientific Research | Suhir E.,University of California at Santa Cruz | And 5 more authors.
Applied Physics Letters | Year: 2012

BaTiO 3/hyperbranched polyester/methacrylate core-shell nanoparticles were studied by varying the shell thickness and the methacrylate ratio. We demonstrated that coalescence typically observed in traditional composites employing polymer matrices is significantly reduced. By modifying the shell thickness, the equivalent filler fraction was tuned from 7 wt. % to 41 wt. %. Obtained permittivities were compared with reported models for two-phase mixtures. The nonlinear behavior of the dielectric constant as a function of the equivalent filler fraction has been fitted with the Bruggeman equation. Methacrylate groups reduce by a decade the loss factor by improving nanoparticles adhesion. The permittivity reaching 85 at 1 kHz makes core-shell nanoparticles a promising material for embedded capacitors. © 2012 American Institute of Physics.

Boudot M.,CNRS Laboratory of Condensed Matter Chemistry, Paris | Boudot M.,Polyrise SAS | Gaud V.,Polyrise SAS | Louarn M.,Polyrise SAS | And 2 more authors.
Chemistry of Materials | Year: 2014

We report a method to prepare hydrophobic, antireflective mesoporous silica-based films on polymer substrates from sol-gel approaches combined with an ammonia vapor treatment (AVT) to avoid any thermal curing. Strategies involving the combination of direct co-condensation of pure and methylated-hybrid silica precursors with further post-functionalization with methyl groups were used. Coatings with the best reflectance (transmittances up to 99.6% in the visible range), full water repellence, and good resistance to abrasion (failures occurred at the substrate interfaces) were obtained by optimizing both sol-gel and AVT conditions. Using in situ, time-resolved, spectroscopic ellipsometry, we demonstrate that the structure of the film can be significantly and rapidly modified from molecular to mesoscales, under the action of H2O and NH3 vapors. The identified mechanism follows a local dissolution/condensation associated to Ostwald ripening that can easily be controlled by adjusting the applied conditions. These structural modifications were much less intense for co-condensed methylated mesoporous matrices due to the stabilizing effect of the organic pendant groups. These conclusions are supported by complementary characterizations obtained with environmental ellipsometry porosimetry, GI-SAXS, SEM-FEG, UV-visible transmittance, crockmeter, and FTIR. © 2014 American Chemical Society.

Boudot M.,Collège de France | Boudot M.,Polyrise SAS | Ceratti D.R.,Collège de France | Faustini M.,Collège de France | And 2 more authors.
Journal of Physical Chemistry C | Year: 2014

In this work, we report the condensation and stabilization of water vapors into water-repellent, methyl-functionalized, mesoporous, silica-based films at room temperature and atmospheric pressure using a soft alcohol-assisted method. The capillary pore fillings due to water adsorption were ensured by a fine control of partial vapor pressures of alcohol and water. A synergic coadsorption of alcohol and water was observed due to a reversible surface energy switching from hydrophobic to hydrophilic induced by the preferential interaction of the alkyl side of the surfactant alcohol molecules with the hydrophobic walls. The influences of the film mesoprosity as well as the type of the alcoholic coadsorbate (methanol, ethanol, and 1-propanol) were investigated, revealing various Kelvin's law-like adsorption behaviors, depending on the alcohol carbon chain length. Interestingly, the stabilization of condensed domains of quasi-pure water phases was obtained in confined hydrophobic spaces by a presumed selective alcohol desorption. It was demonstrated that a small quantity of remaining Si-OH groups at the pore surface was sufficient to stabilize water nanodomains in hydrophobic pores. These results were based on in situ ellipsometric investigations, that further allowed measuring the wetting angle of water droplets trapped within the porous network, from which we could evaluate the quantity of polar -OH groups remaining in the methyl-functionalized, mesoporous, silica-based films. This first insight in alcohol/water coadsorption may open the door toward new generation of alcohol sensors. © 2014 American Chemical Society.

Loading Polyrise SAS collaborators
Loading Polyrise SAS collaborators