References of "Jérôme, Christine"
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See detailAliphatic polyphosphates: a promising family of polymers for drug delivery
Vanslambrouck, Stéphanie ULg; Clément, Benoit; Riva, Raphaël ULg et al

Poster (2015, May 18)

Thanks to their biocompatibility and biodegradability, polyphosphates are appealing polymers for biomedical applications. In contrast to polyesters, polyphosphate properties and functionality are easily ... [more ▼]

Thanks to their biocompatibility and biodegradability, polyphosphates are appealing polymers for biomedical applications. In contrast to polyesters, polyphosphate properties and functionality are easily tuned via the chemical nature of the lateral chains. In this work, a series of amphiphilic PEO-block-polyphosphate copolymers were synthesized by organo-catalyzed ring-opening polymerization of cyclic phosphates. These polymers are directly dissolved in water in the absence of any organic solvent and they self-assemble to form nanoparticles Our work aims at changing the lateral chain of polyphosphates to investigate the influence of this structural modification on (i) the size of the nanoparticles, (ii) the critical aggregation concentration, (iii) the encapsulation of an hydrophobic drug in the core of the nanoparticles and, finally, (iv) the release of the drug. [less ▲]

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See detailPrerparation of graphene oxide-poly(methyl methacrylate) nanocompposites by a precipitation polymerization process and their dielectric and rheological characterization
Alkarmo, Walid ULg; Thomassin, Jean-Michel ULg; Macosko, Christopher et al

Poster (2015, May 18)

The graphene sheet, a flat monolayer composed of sp2-bonded carbon atoms packed into a two-dimensional honeycomb structure, has attracted a tremendous attention due to its extraordinary electrical ... [more ▼]

The graphene sheet, a flat monolayer composed of sp2-bonded carbon atoms packed into a two-dimensional honeycomb structure, has attracted a tremendous attention due to its extraordinary electrical, thermal, and mechanical properties. Graphene nanosheets–poly(methyl methacrylate) GN/PMMA nanocomposites were prepared via a precipitation polymerization process in a water/methanol mixture and thermal or chemical reduction of graphene oxide (GO). Scanning electron and transmission electron microscopies confirmed that the precipitate consists of polymer particles (<1μm) surrounded by the GO sheets. The GO sheets acts as a surfactant and adsorbs on the interface between polymerized PMMA particles and solvent mixture. Parallel dielectric and rheological characterization demonstrated that the thermal reduction is a quite fast process without significant degradation of the polymer. In addition, the main increase in electrical conductivity occurred during the first minutes of the thermal treatment but continued for about 30 min. The absence of dramatic change in the storage modulus confirmed that the increase in conductivity was not due to alteration of the particle dispersion. The addition of GO sheets had a dramatic influence on the glass transition (Tg) temperature of PMMA with an increase of 8 °C at only 0.2 wt %. This Tg increase has been attributed to the restricted mobility of PMMA chains which have been grafted onto the graphene surfaces during the in-situ polymerization. However, at GO content higher than 0.7 wt %, the glass transition decreases. This drop may be attributed to the increase in the number of stacked graphene layers. The obtained GN/PMMA composites not only have enhanced mechanical properties but also achieved electrical conductivity higher than 10 −2 S/m at 0.4 wt % of GO. The study should open up new opportunities in the design of GN-based polymer nanocomposites. [less ▲]

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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 ▲]

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See detailIntercalation of cationic aliphatic polyphosphates between montmorillonite nanosheets towards flame-retardant polymer materials
Carion, Stéphan ULg; Lecomte, Philippe ULg; Thomassin, Jean-Michel ULg et al

Poster (2015, May 18)

Among the strategies used to impart flame-retardant properties to polymer materials, the most effective ones include the addition of phosphorous compounds such as organic polyphosphates and the dispersion ... [more ▼]

Among the strategies used to impart flame-retardant properties to polymer materials, the most effective ones include the addition of phosphorous compounds such as organic polyphosphates and the dispersion of layered silicates (nanoclays). The aim of this work is to combine both approaches by the dispersion of nanoclays, organomodified by cationic aliphatic polyphosphates, into a polymer matrix. In this work, the synthesis of an aliphatic polyphosphate end-capped by an imidazolium cation followed by its intercalation between montmorillonite nanoclays sheets is reported. In a first step, the polyphosphate was synthesized by ring-opening polymerization of the corresponding cyclic phosphate using 1-(11-hydroxy-undecyl)-3-methylimidazolium bromide as initiator. This polymerization was catalyzed by DBU and a thiourea derivative. This polymer was characterized by different techniques (31P and 1H NMR, SEC, TGA, DSC). Finally, the cationic end-functionalized polymer was exchanged with sodium cations present in montmorillonite. The intercalation of the polyphosphate between the clay nanosheets was proved by X-Ray Diffraction (XRD) and thermogravimetric analysis (TGA). This last technique was also used to determine the influence of the intercalation on the thermal stability of the polyphosphate.polyphosphates, into a polymer matrix. In this work, the synthesis of an aliphatic polyphosphate end-capped by an imidazolium cation followed by its intercalation between montmorillonite nanoclays sheets is reported. In a first step, the polyphosphate was synthesized by ring-opening polymerization of the corresponding cyclic phosphate using 1-(11-hydroxy-undecyl)-3-methylimidazolium bromide as initiator. This polymerization was catalyzed by DBU and a thiourea derivative. This polymer was characterized by different techniques (31P and 1H NMR, SEC, TGA, DSC). Finally, the cationic end-functionalized polymer was exchanged with sodium cations present in montmorillonite. The intercalation of the polyphosphate between the clay nanosheets was proved by X-Ray Diffraction (XRD) and thermogravimetric analysis (TGA). This last technique was also used to determine the influence of the intercalation on the thermal stability of the polyphosphate. [less ▲]

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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 ▲]

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See detailA tool for the precision synthesis of poly(ionic liquid)s in water
Cordella, Daniela ULg; Kermagoret, Anthony; Debuigne, Antoine ULg et al

Conference (2015, May 18)

In recent years, poly(ionic liquid)s (PIL)s were found to take an enabling role in important fields of polymer chemistry and material science. PILs combine the unique properties of ionic liquids with the ... [more ▼]

In recent years, poly(ionic liquid)s (PIL)s were found to take an enabling role in important fields of polymer chemistry and material science. PILs combine the unique properties of ionic liquids with the flexibility and properties of macromolecular architectures giving rise to a new family of functional polymers that opens new area of applications such as polymer electrolytes in electrochemical devices, powerful dispersants and stabilizers, absorbing membranes, precursors for carbon materials, porous polymers, etc. In this communication, we will report on the implementation of organometallic-mediated radical polymerization (OMRP) technique for the precision synthesis of unprecedented PILs (co)polymers. We will discuss how an organocobalt complex can efficiently control the growth of vinyl imidazolium chains and lead to PILs with predicted molar masses and low polydispersities under mild experimental conditions, which provide low temperatures (compared to the conventional radical polymerization techniques) and also the use of water as green polymerization medium. The huge potential of this system will be also highlighted by describing the one-pot synthesis of vinyl imidazolium-based block copolymers in heterogeneous conditions. This OMRP is unique for providing well-defined vinyl imidazolium based-copolymers opening for advanced PILs applications. [less ▲]

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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 ▲]

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See detailChitosan-coated electrospun nanofibers with antibacterial activity
Croisier, Florence ULg; Sibret, Pierre ULg; Dupont-Gillain, Christine C. et al

in Journal of Materials Chemistry B (2015), 3(17), 3508-2517

Charged nanofibers were prepared by electrospinning (ESP) poly(ε-caprolactone) with a copolymer bearing carboxylic acid functions. The presence of these functions allowed exposing some negative charges on ... [more ▼]

Charged nanofibers were prepared by electrospinning (ESP) poly(ε-caprolactone) with a copolymer bearing carboxylic acid functions. The presence of these functions allowed exposing some negative charges on the fiber surface, by dipping the fibers in a phosphate buffer. A layer of chitosan, a polycation in acidic medium, was then deposited on the nanofiber surface, thanks to electrostatic attraction. Fibers were characterized at each step of the process and the influence of the copolymer architecture on chitosan deposition was discussed. The antibacterial activity of the resulting fibers was finally assessed. [less ▲]

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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 ▲]

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See detailControlled synthesis of ethylene-vinyl acetate based copolymers by organometallic mediated radical polymerization
Demarteau, Jérémy ULg; Kermagoret, Anthony ULg; Jérôme, Christine ULg et al

in Matyjaszewski, Krzysztof; Sumerlin, Brent S.; Tsarevsky, Nicolay V. (Eds.) et al Controlled Radical Polymerization: Materials (2015)

The controlled radical copolymerization of ethylene (E) and vinyl acetate (VAc) is further investigated by organometallic- mediated radical polymerization (OMRP) using Co(acac)2 as controlling agent at ... [more ▼]

The controlled radical copolymerization of ethylene (E) and vinyl acetate (VAc) is further investigated by organometallic- mediated radical polymerization (OMRP) using Co(acac)2 as controlling agent at ethylene pressure up to 100 bar. The effect of ethylene pressure on kinetics, level of control and copolymer composition, is discussed. Ethylene-Vinyl Acetate copolymers (EVAs) with low dispersities and ethylene content reaching 57 mol% are notably reported. This work also successfully addresses the precision design of EVA-containing block copolymers, i.e. PVAc-block-EVA. In this case, the order of the synthesis of the blocks is a key parameter. The “PVAc-first” strategy is by far more practical and efficient. [less ▲]

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See detailLinear and propeller-like fluoro-isoindigo based donor–acceptor small molecules for organic solar cells
Ouhib, Farid ULg; Tomassetti, Mirco ULg; Dierckx, Wauter et al

in Organic Electronics (2015), 20

Two donor–acceptor type fluoro-isoindigo based small molecule semiconductors are syn- thesized and their optical, electrochemical, thermal, and charge transport properties are investigated. The two ... [more ▼]

Two donor–acceptor type fluoro-isoindigo based small molecule semiconductors are syn- thesized and their optical, electrochemical, thermal, and charge transport properties are investigated. The two molecular chromophores differ by their architecture, linear (M1) vs propeller-like (M2). Both molecules present a broad absorption in the visible range and a low optical HOMO–LUMO gap (?1.6 eV). AFM images of solution-processed thin films show that the trigonal molecule M2 forms highly oriented fibrils after a few seconds of solvent vapor annealing. The materials are evaluated as electron donor components in bulk heterojunction organic solar cells using PC61BM as the electron acceptor. The devices based on the propeller-like molecule M2 exhibit a high open-circuit voltage (around 1.0 V) and a power conversion efficiency of 2.23%. [less ▲]

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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)

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See detailDouble thermo-responsive hydrogels from poly(vinylcaprolactam) containing diblock and triblock copolymers
Thomassin, Jean-Michel ULg; Mathieu, Kevin ULg; Kermagoret, Anthony ULg et al

in Polymer Chemistry (2015), 6(10), 1856-1864

The thermally-induced gelation and gel properties of concentrated aqueous solutions of double thermoresponsive poly(N-vinylamide)-based di- and triblock copolymers are studied by rheology. The copolymers ... [more ▼]

The thermally-induced gelation and gel properties of concentrated aqueous solutions of double thermoresponsive poly(N-vinylamide)-based di- and triblock copolymers are studied by rheology. The copolymers under investigation, prepared by cobalt-mediated radical polymerization and coupling reactions, are composed of poly(vinylcaprolactam) (PNVCL) blocks and of a statistical poly(vinylcaprolactam-stat-vinylpyrrolidone) segment with a cloud point temperature (TCP) higher than that of PNVCL. Heating the di- and triblock solutions beyond the first phase transition temperature favors gel formation while heating above the second TCP leads to opaque gels without macroscopic demixing. Moduli of the triblock hydrogels are systematically higher than those of the corresponding diblocks, even above the second transition. Rheological data suggest distinct micellar structures for each copolymer architecture: densely packed micelles of diblocks and 3-D networks of bridged micelles for triblocks. Strain sweep experiments also emphasize the positive effect of the micelle bridging on the elasticity and stability of the hydrogels. The formation and properties of the obtained gels are also shown to depend on the copolymer concentration, block length, and composition. Addition of salt also allows us to tune the phase transition temperatures of these double thermoresponsive hydrogels. [less ▲]

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See detailIn situ investigation of scCO2 assisted impregnation of drug into polymer by high pressure FTIR micro-spectroscopy
Champeau, Mathilde ULg; Thomassin, Jean-Michel ULg; Jérôme, Christine ULg et al

in Analyst (2015), 140(3), 869-879

An original experimental set-up combining a FTIR microscope with a high pressure cell has been built in order to analyze in-situ the impregnation of solute into microscopic polymer samples, such as fibers ... [more ▼]

An original experimental set-up combining a FTIR microscope with a high pressure cell has been built in order to analyze in-situ the impregnation of solute into microscopic polymer samples, such as fibers or films, subjected to supercritical CO2. Thanks to this experimental set-up, key factors governing the impregnation process can be simultaneously followed such as the swelling of the polymeric matrix, the CO2 sorption, the kinetic of impregnation and the drug loading into the matrix. Moreover, the solute/polymer interactions and the speciation of the solute can be analyzed. We have monitored in situ the impregnation of aspirin and ketoprofen into PEO (Polyethylene Oxide) platelets at T=40°C and P=5; 10 and 15 MPa. The kinetic of impregnation of aspirin was quicker than the one of ketoprofen and the final drug loading was also higher in case of aspirin. Whereas the CO2 sorption and the PEO swelling remain constant when PEO is just subjected to CO2 under isobaric conditions, we noticed that both parameters can increase while the drug impregnates PEO. Coupling these results with DSC measurements, we underlined the plasticizing effect of the drug that also leads to decrease the crystallinity of PEO in situ thus favoring the sorption of CO2 molecules into the matrix and the swelling of the matrix. The plasticizing effect increases with the drug loading. Finally, the speciation of drug was investigated considering the shift of the carboxyl bands of the drugs. Both drugs were found to be mainly homogeneously dispersed into PEO. [less ▲]

Detailed reference viewed: 47 (9 ULg)