References of "Grignard, Bruno"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailOrganocatalytic promoted coupling of carbon dioxide with epoxides: a rational investigation of the cocatalytic activity of various hydrogen bond donors
Alves, Margot ULg; Grignard, Bruno ULg; Gennen, Sandro ULg et al

in Catalysis Science & Technology (in press)

A catalytic platform based on an onium salt used in combination with organic cocatalysts of various structures was developed for the efficient CO2/epoxide coupling under mild conditions. Through detailed ... [more ▼]

A catalytic platform based on an onium salt used in combination with organic cocatalysts of various structures was developed for the efficient CO2/epoxide coupling under mild conditions. Through detailed kinetic studies by in-situ FT-IR spectroscopy, a rational investigation of the efficiency of a series of commercially available hydrogen bond donors co-catalysts was realized and the influence of different parameters such as the pressure, the temperature, the catalyst loading, and the nature of the epoxide on the reaction kinetics was evaluated. Fluorinated alcohols were found to be more efficient than other hydrogen bond donor activators proposed previously in the literature under similar conditions. [less ▲]

Detailed reference viewed: 27 (8 ULg)
Full Text
Peer Reviewed
See detailFluorinated alcohols as activators for the solvent-free chemical fixation of carbon dioxide onto epoxides
Gennen, Sandro ULg; Alves, Margot ULg; Méreau, Raphaël et al

in ChemSusChem (2015), 8(11), 1845-1849

The addition of fluorinated alcohols to onium salts provides highly efficient organocatalysts for the chemical fixation of CO2 onto epoxides under mild experimental conditions. The combination of online ... [more ▼]

The addition of fluorinated alcohols to onium salts provides highly efficient organocatalysts for the chemical fixation of CO2 onto epoxides under mild experimental conditions. The combination of online kinetic studies, NMR titrations and DFT calculations allows understanding this synergistic effect that provides an active organocatalyst for CO2/epoxides coupling. [less ▲]

Detailed reference viewed: 37 (13 ULg)
See detailNon-isocyanate polyurethane: from the monomer synthesis to foamed materials
Gennen, Sandro ULg; Alves, Margot ULg; Tassaing, Thierry et al

Poster (2015, May 18)

Polyurethane (PU) is one of the most important polymers in our everyday life with numerous applications such as thermosets, thermoplastics, elastomers, adhesives, sealants, coatings, rigid and flexible ... [more ▼]

Polyurethane (PU) is one of the most important polymers in our everyday life with numerous applications such as thermosets, thermoplastics, elastomers, adhesives, sealants, coatings, rigid and flexible foams... Classically, PUs are produced by a step-growth polymerization between diols and diisocyanates. However, isocyanates are harmful upon prolonged exposure to vapours which can lead to health issues such as asthma and skin irritation. In addition, isocyanates are produced from even more toxic and explosive phosgene. Due to these problems in combination with increasing regulatory scrutiny, there is today a need to develop isocyanate- and phosgene free- PU synthesis, also called non-isocyanate polyurethane or NIPUs. One of the most promising alternatives to the conventional synthesis of PU relies on the step-growth polymerization between bicyclic carbonate monomers and diamines, but until now, obtaining high molar mass NIPUs in a short time still remains a challenge. This study will be focused on three objectives: 1) The synthesis of CO2-sourced biscyclic carbonates by CO2/epoxide coupling using new highly efficient bicomponent organocatalysts allowing the fast conversion of epoxides into the corresponding cyclic carbonates under mild and solvent-free conditions. 2) The synthesis of high molar mass NIPUs from CO2-sourced monomers and diamines thanks to the use of efficient organocatalysts. A series of organic compounds interacting with cyclic carbonates by hydrogen bonding were first identified and their catalytic activity was highlighted by a model reaction between ethylene carbonate and a primary amine before extrapolation to NIPU synthesis. 3) The scCO2-assisted foaming of CO2-sourced NIPUs with production of potential carbon zero-emission materials with low thermal conductivity [less ▲]

Detailed reference viewed: 53 (1 ULg)
See detailNew efficient bicomponent organocatalysts for the chemical fixation of CO2 onto epoxides: a theoretical study
Alves, Margot ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

Poster (2015, May 18)

Regarding the economic and environmental issues, valorising CO2 as a C1 feedstock for producing useful building blocks is seducing as it is a free and abundant waste resulting from the human activity ... [more ▼]

Regarding the economic and environmental issues, valorising CO2 as a C1 feedstock for producing useful building blocks is seducing as it is a free and abundant waste resulting from the human activity. Cyclic carbonates are useful compounds that found application as green solvents, electrolytes for lithium battery or monomers for polycarbonates or polyurethanes synthesis. These cyclocarbonates can be synthesized with a total atom economy by chemical fixation of CO2 onto epoxides using organometallic complexes or organocatalysts. To date, although this area of research has been the subject of many studies, the identification and development of (organo)catalysts highly efficient under mild experimental conditions still remains challenging. In this context, we developed a new organocatalytic platform based on the use of ammonium salts in combination with single or double hydrogen bond donor activators derived from fluorinated alcohols that showed unexpected booster effect. In this contribution, the ammonium/fluoroalcohol promoted CO2/propylene oxide coupling was investigated through detailed kinetic studies by IR spectroscopy under pressure and results were compared to the most efficient organocatalysts based on ammonium salts and (multi)phenolic derivatives that were reported in the literature. In order to finely understand the reaction mechanism, this study was completed by molecular modeling. DFT calculations showed that the addition of H-bond donors (HBD) with hexafluoroisopropanol functionalities modified the mechanism of the ammonium promoted coupling of CO2 with epoxides. HBDs dramatically decreased the epoxide ring-opening step barrier which highlights the key role of the fluorinated activators in stabilizing the intermediates and transitions states by inter- and intra-molecular hydrogen bonds. [less ▲]

Detailed reference viewed: 40 (1 ULg)
See detailDesign of new multifunctional nanocarriers for protein delivery
Parilti, Rahmet ULg; Jérôme, Christine ULg; Howdle, Steven M. et al

Conference (2015, May 18)

Polymeric nanoparticles have been extensively investigated for their biomedical applications especially as drug carriers. However, efficient encapsulation and delivery of therapeutic proteins in targeted ... [more ▼]

Polymeric nanoparticles have been extensively investigated for their biomedical applications especially as drug carriers. However, efficient encapsulation and delivery of therapeutic proteins in targeted manner still present challenges. This project aims to develop a novel one-pot strategy to obtain nanoparticles able to carry proteins in their core, as well as bearing targeting and/or imaging agents on their surface. In addition to this objective, polymerizations are carried out in supercritical carbon dioxide (scCO2), which confers environmentally benign features to the process. Dispersion polymerizations of hydrophilic monomer 2-hydroxyethyl methacrylate (HEMA) in are carried out in scCO2 in the presence of an initiator, cross-linker and CO2-philic photoclevable stabilizer. Upon exposure to UV light, the o-nitrobenzyl junctions present at the surface of the particles are cleaved, thus providing water dispersible hydrogels. Spherical monodisperse nanoparticles were successfully synthesized in scCO2 with two different conditions. Milder reaction conditions were achieved by using 2,2'-Azobis(4-methoxy-2,4-dimethyl valeronitrile (V70) as an initiator which opens up the platform for one-pot protein encapsulation in scCO2. [less ▲]

Detailed reference viewed: 20 (2 ULg)
See detailCarbon dioxide, a cheap bio-sourced building block for cyclic carbonates and non-isocyanate polyurethanes
Gennen, Sandro ULg; Alves, Margot ULg; Tassaing, Thierry et al

Poster (2015, May 03)

Due to concerns about global warming combined with the decrease of fossil resources, new carbon feedstocks that are abundant, renewable, non-toxic, inexpensive and environmentally friendly must be ... [more ▼]

Due to concerns about global warming combined with the decrease of fossil resources, new carbon feedstocks that are abundant, renewable, non-toxic, inexpensive and environmentally friendly must be explored to produce chemicals. Besides the valorization of bio-based raw materials, the chemical transformation of carbon dioxide into added-value products has gained interest in both academia and industry. To date, the chemical fixation of CO2 onto epoxides with the formation of cyclic carbonates is one of the most promising ways to valorize CO2 at an industrial scale. Indeed, cyclic carbonates find applications as electrolytes in lithium ion batteries, as aprotic polar solvents or as useful intermediates for polycarbonates. Cyclic carbonates also react with primary amines to produce 2-hydroxyethylurethane. This reaction can be extrapolated to the synthesis of non-isocyanate polyurethanes (NIPU) by polyaddition of bifunctional cyclic carbonates with diamines.5 This study aims (i) at developing a new highly efficient organocatalyst for the synthesis of cyclic carbonates under mild experimental conditions and (ii) their valorization as monomers to produce non-isocyanate polyurethanes. First, we have identified a bicomponent organocatalyst, composed of a judicious combination of an organocatalyst and an activator, for the very fast synthesis of cyclic carbonates from CO2 and epoxides under very mild reaction conditions. Kinetics of reactions were followed by online Raman spectroscopy measurements under pressure. NMR titrations were realized to evidence the mechanism of activation of this novel organocatalytic system that will be discussed in detail in this talk. The second objective relies on the development of new efficient organocatalysts for the synthesis of high molar masses NIPUs in short reaction times. Organic compounds interacting with the cyclic carbonate by hydrogen bonding were identified and their catalytic activity was demonstrated for model compounds. [less ▲]

Detailed reference viewed: 75 (1 ULg)
See detailCarbon dioxide and vegetable ooil for the synthesis of bio-based polymer precursor
Alves, Margot ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

Conference (2015, March 18)

Detailed reference viewed: 12 (2 ULg)
Full Text
Peer Reviewed
See detailOrganocatalytic synthesis of bio-based cyclic carbonates from CO2 and vegetable oils
Alves, Margot ULg; Grignard, Bruno ULg; Gennen, Sandro ULg et al

in RSC Advances (2015), 5

Bio-based cyclic carbonates were synthesized by coupling CO2 with epoxidized linseed oil using a catalytic platform composed of a bicomponent organocatalyst. A screening of the catalytic activity of a ... [more ▼]

Bio-based cyclic carbonates were synthesized by coupling CO2 with epoxidized linseed oil using a catalytic platform composed of a bicomponent organocatalyst. A screening of the catalytic activity of a series of organic salts and ionic liquids used in combination with (multi)phenolic or fluorinated hydrogen bond donors was realized before highlighting the synergistic effect between the organocatalyst and the most efficient cocatalysts. These kinetics studies, followed by IR spectroscopy under pressure, enabled to optimize the reaction conditions and to provide quantitative formation of the cyclocarbonated vegetable oil in short reaction time without using any organic solvent. [less ▲]

Detailed reference viewed: 28 (5 ULg)
Full Text
Peer Reviewed
See detailSmall Angle X-ray Scattering Insights into the Architecture-Dependent Emulsifying Properties of Amphiphilic Copolymers in Supercritical Carbon Dioxide
Alaimo, David ULg; Hermida Merino, Daniel; Grignard, Bruno ULg et al

in Journal of Physical Chemistry B (2015), 119

The supramolecular assembly of a series of copolymers combining a PEO-rich hydrophilic and fluorinated CO2-philic sequences is analysed by synchrotron small-angle xray scattering (SAXS) in supercritical ... [more ▼]

The supramolecular assembly of a series of copolymers combining a PEO-rich hydrophilic and fluorinated CO2-philic sequences is analysed by synchrotron small-angle xray scattering (SAXS) in supercritical CO2, as well as in water/CO2 emulsions. These copolymers were designed to have the same molecular weight and composition, and to differ only by their macromolecular architecture. The investigated copolymers have random, block, and palm-tree architectures. Besides, thermo-responsive copolymer is also analysed, having a hydrophilic sequence becoming water-insoluble around 41 °C, i.e. just above the critical point of CO2. At the length scale investigated by SAXS, only the random copolymer appears to self-assemble in pure CO2, in the form of a disordered microgel-like network. The random, block and thermo-responsive copolymers are all able to stabilize water/CO2 emulsions but not the copolymer with the palm-tree architecture, pointing at the importance of macromolecular architecture for the emulsifying properties. A modelling of the SAXS data shows that the block and the thermo-responsive copolymers form spherical micelle-like structures containing about 70 % water and 30 % polymer. [less ▲]

Detailed reference viewed: 70 (12 ULg)
Full Text
Peer Reviewed
See detailBlock, random and palm-tree amphiphilic fluorinated copolymers: controlled synthesis, surface activity and use as dispersion polymerization stabilizers
Alaimo, David ULg; Beigbeder, Alexandre; Dubois, Philippe et al

in Polymer Chemistry (2014), 5(18), 5273-5282

Detailed reference viewed: 65 (16 ULg)
See detailOn the use of carbon dioxide and vegetable oil for the synthesis of bio-based cyclic carbonates
Alves, Margot ULg; Tassaing, Thierry; Méreau, Raphaël et al

Conference (2014, August 27)

The uncertain cost of petroleum and its expected depletion in the near future prompted the scientific community to search for new sources of carbon just inexpensive, abundant and easily exploitable ... [more ▼]

The uncertain cost of petroleum and its expected depletion in the near future prompted the scientific community to search for new sources of carbon just inexpensive, abundant and easily exploitable. Combining the use of renewable resources such as vegetable oils and carbon dioxide as a carbon source for the development of a sustainable chemistry is very promising. Thus, this research project fits within the framework of the chemical fixation of CO2 and the utilization of vegetable oils as a substitute for basic petroleum derivatives for the production of new monomers and new bio-based organic polymers. As a first step, the catalytic synthesis of cyclic carbonate monomers from CO2 and epoxidized vegetable oils (and/or the corresponding fatty esters) will be considered. The synthesis of non-isocyanates polyurethanes (NIPUS) will then be performed by reacting in bulk these new monomers with diamines under mild heating. In this talk, we will present the results that we have obtained on the first step of the process. Namely, we have investigated various catalytic platforms enabling the cycloaddition of CO2 on epoxidized oils in the most efficient way under mild conditions. For such task, in situ kinetic follow-up of this reaction has been performed by FT-IR or Raman spectroscopy in order to identify the best catalytic systems and to evaluate the influence of various parameters (pressure, temperature catalyst concentration, nature of epoxidized oil) on the yields and the reaction kinetics. Then, the most efficient catalytic systems have been investigated by molecular modeling in order to identify the key structural parameters of the catalyst that govern its efficiency. [less ▲]

Detailed reference viewed: 17 (2 ULg)
See detailOn the use of carbon dioxide and vegetable oil for the synthesis of bio-based cyclic carbonates
Alves, Margot ULg; Tassaing, Thierry; Mereau, R. et al

Poster (2014, July 03)

Detailed reference viewed: 12 (2 ULg)
See detailChemical fixation of CO2 with epoxides: towards the synthesis of cyclic carbonates, precursors of CO2-based polyurethanes
Gennen, Sandro ULg; Grignard, Bruno ULg; Gilbert, Bernard ULg et al

Poster (2014, May 20)

Due to concerns about global warming combined with the decrease of fossil resources, the chemical transformation of carbon dioxide into added-value products has gained interest in both academic and ... [more ▼]

Due to concerns about global warming combined with the decrease of fossil resources, the chemical transformation of carbon dioxide into added-value products has gained interest in both academic and industrial fields. To date, the chemical fixation of CO2 onto epoxides is one of the most promising ways to valorize carbon dioxide at an industrial scale . Indeed, cyclic carbonates are useful intermediates for polycarbonates and polyurethanes synthesis or can be used as electrolytes in lithium ion batteries. Although fixation of carbon dioxide onto epoxides has been extensively studied, the design of highly effective catalysts still remains a challenge. Here, we present a new highly efficient biocomponent organocatalyst based on the use of an ammonium salt (TBAI) in combination with single or double hydrogen bond donors activators (typically fluorinated alcohols). [less ▲]

Detailed reference viewed: 63 (13 ULg)
See detailOrganocatalyzed synthesis of cyclic carbonates from epoxidized vegetable oils and carbon dioxide
Alves, Margot ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

Conference (2014, March)

The present project relies on the chemical fixation of CO2 and the utilization of vegetable oils as a substitute for basic petroleum derivatives for the production of new monomers and new bio-based ... [more ▼]

The present project relies on the chemical fixation of CO2 and the utilization of vegetable oils as a substitute for basic petroleum derivatives for the production of new monomers and new bio-based organic polymers. In this context, a “greener” approach has been developed to produce bio-sourced polyurethanes by reaction of bio-based cyclic carbonates and amines. Bio-based cyclic carbonates can be synthesised with a total atom economy by chemical fixation of carbon dioxide onto an epoxidized vegetable oil using an appropriate catalyst. However, the conventional catalysts exhibit high catalytic activity only at high temperature and/or pressure or are sensitive to moistures water and/or oxygen. The aim of the present study is to investigate new organocatalytic platforms enabling the cycloaddition of CO2 onto epoxidized oils in the most efficient way under mild conditions. For such task, in situ kinetic follow-up of the cycloaddition of model epoxides and epoxidized oils onto CO2 has been performed by FT-IR spectroscopy in order to to determine the catalytic activity of new binary organocatalytic systems and to evaluate the influence of various parameters (pressure, temperature, catalyst concentration, nature of the epoxide) on the yields and the reaction kinetics. Then, few catalytic systems have been investigated by molecular modeling in order to understand the reaction mechanism. [less ▲]

Detailed reference viewed: 11 (3 ULg)
Full Text
Peer Reviewed
See detailGold nanorods with phase-changing polymer corona for remotely near-infrared-triggered drug release
Liu, Ji ULg; Detrembleur, Christophe ULg; Grignard, Bruno ULg et al

in Chemistry : An Asian Journal (2014), 9(1), 275-288

Herein, we report a new drug-delivery system (DDS) that is comprised of a near-infrared (NIR)- light-sensitive gold-nanorod (GNR) core and a phase-changing poly(e-caprolactone)- b-poly(ethylene glycol ... [more ▼]

Herein, we report a new drug-delivery system (DDS) that is comprised of a near-infrared (NIR)- light-sensitive gold-nanorod (GNR) core and a phase-changing poly(e-caprolactone)- b-poly(ethylene glycol) polymer corona (GNR@PCL-b-PEG). The underlying mechanism of the drugloading and triggered-release behaviors involves the entrapment of drug payloads among the PCL crystallites and a heat-induced phase change, respectively. A low premature release of the pre-loaded doxorubicin was observed in PBS buffer (pH 7.4) at 37 °C (<10% of the entire payload after 48 h). However, release could be activated within 30 min by conventional heating at 50 °C, above the Tm of the crystalline PCL domain (43.5 °C), with about 60% release over the subsequent 42 h at 37 °C. The NIR-induced heating of an aqueous suspension of GNR@PCL-b- PEG under NIR irradiation (802 nm) was investigated in terms of the irradiation period, power, and concentrationdependent heating behavior, as well as the NIR-induced shape-transformation of the GNR cores. Remotely NIR-triggered release was also explored upon NIR irradiation for 30 min and about 70% release was achieved in the following 42 h at 37°C, with a mild warming (<4 °C) of the surroundings. The cytotoxicity of GNR@PCL-b-PEG against the mouse fibroblastic-like L929 cell-line was assessed by MTS assay and good compatibility was confirmed with a cell viability of over 90% after incubation for 72 h. The cellular uptake of GNR@PCL-b-PEG by melanoma MEL-5 cells was also confirmed, with an averaged uptake of 1250 ( ± 110) particles cell-1 after incubation for 12 h (50 mg mL-1). This GNR@PCL-b-PEG DDS is aimed at addressing the different requirements for therapeutic treatments and is envisaged to provide new insights into DDS targeting for remotely triggered release by NIR activation. [less ▲]

Detailed reference viewed: 30 (9 ULg)
See detailValorisation du CO2 et d'huiles végétales pour la stynthèse organocatalytique de carbonates cycliques
Alves, Margot ULg; Méreau, Raphaël; Grignard, Bruno ULg et al

Conference (2014)

L’épuisement annoncé des réserves pétrolières ainsi que le coût incertain du pétrole à court terme ont poussé la communauté scientifique à chercher de nouvelles sources de carbone moins coûteuses ... [more ▼]

L’épuisement annoncé des réserves pétrolières ainsi que le coût incertain du pétrole à court terme ont poussé la communauté scientifique à chercher de nouvelles sources de carbone moins coûteuses, abondantes et facilement exploitables. Ainsi, l’exploitation de ressources renouvelables telles que les huiles végétales et le dioxyde de carbone est très prometteur pour le développement d’une chimie plus durable. Dans ce contexte, ce projet de recherche concerne la synthèse de polyuréthanes bio- et CO2-sourcés. Dans une première étape, la synthèse organocatalytique d’un monomère carbonate cyclique est réalisée par cycloaddition du CO2 sur l’huile végétale époxydée. Le polyuréthane non-isocyanate est ensuite obtenu après polymérisation en masse entre ce monomère et une diamine dans des conditions de température douces. Cette présentation ne concernera que les résultats obtenus pour la première étape de synthèse. Nous avons donc testé et comparé l’activité de différentes plateformes catalytiques permettant de réaliser efficacement la cycloaddition du dioxyde de carbone sur les huiles époxydées dans des conditions douces. Pour cela, un suivi cinétique in situ de la réaction a été réalisé par spectroscopie infrarouge à transformée de Fourier (FTIR) afin d’identifier le système catalytique le plus efficace. L’influence de plusieurs paramètres (pression, température, nature de l’huile, concentration du catalyseur) sur le rendement et la cinétique de réaction a également été évalué. Enfin, le système le plus efficace a fait l’objet d’une étude par modélisation moléculaire de type DFT pour déterminer les éléments structuraux gouvernant son activité catalytique. [less ▲]

Detailed reference viewed: 7 (2 ULg)
Full Text
See detailSynthesis of new biomimetic and biodegradable polymers for clinical use
Clement, Benoît ULg; Grignard, Bruno ULg; Koole, Leo et al

Conference (2012, November 15)

Detailed reference viewed: 33 (7 ULg)
Full Text
See detailSynthesis in scCO2 of nano-hydrogels for proteins delivery
Alaimo, David ULg; Grignard, Bruno ULg; Fustin, Charles-André et al

Conference (2012, November 14)

Detailed reference viewed: 26 (5 ULg)