References of "Detrembleur, Christophe"
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See detailIn situ bidentate to tetradentate ligand exchange reaction in cobalt-mediated radical polymerization
Kermagoret, Anthony ULg; Jérôme, Christine ULg; Detrembleur, Christophe ULg et al

in European Polymer Journal (in press)

Organometallic-mediated radical polymerization (OMRP) has seen a significant growth in the last years notably due to the development of new metal complexes, especially cobalt derivatives. Despite of this ... [more ▼]

Organometallic-mediated radical polymerization (OMRP) has seen a significant growth in the last years notably due to the development of new metal complexes, especially cobalt derivatives. Despite of this, none of the reported complexes offers optimal control for monomers with very different reactivity, which somewhat limits the synthesis of copolymers. In order to expand the scope of cobalt-mediated radical polymerization (CMRP), we investigated an in situ ligand exchange reaction for modulating the properties of the cobalt complex at the polymer chain-end and adjusting the C-Co bond strength involved in the control process. With the aim of improving the synthesis of poly(vinyl acetate)-b-poly(n-butyl acrylate) copolymers, bidentate acetylacetonate ligands, which impart high level of control to the polymerization of vinyl acetate (VAc), were replaced in situ at the PVAc-cobalt chain-end by tetradentate Salen type ligands that are more suited to acrylates. [less ▲]

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See detailThermo-responsive gold/poly(vinyl alcohol)-b-poly(N-vinylcaprolactam) core–corona nanoparticles as a drug delivery system
Liu, Ji ULg; Detrembleur, Christophe ULg; Hurtgen, Marie et al

in Polymer Chemistry (2014), 5(18), 5289-5299

Core–corona gold/poly(vinyl alcohol)-b-poly(N-vinylcaprolactam) nanoparticles (gold@PVOH-b-PNVCL NPs) were fabricated via an in situ method, where a gold salt was reduced within the macromolecular aqueous ... [more ▼]

Core–corona gold/poly(vinyl alcohol)-b-poly(N-vinylcaprolactam) nanoparticles (gold@PVOH-b-PNVCL NPs) were fabricated via an in situ method, where a gold salt was reduced within the macromolecular aqueous solution. Arrangement of macromolecular chains on the surface of gold cores was studied by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy and infrared spectroscopy. The responsiveness to temperature and the preserved colloidal stability of the gold@PVOH-b-PNVCL NPs above the lower critical solution temperature (LCST) were confirmed by dynamic light scattering and turbidity measurements. The drug loading capacity (DLC of ca. 1.3–2.8 wt%) of the gold@PVOH-b-PNVCL NPs as a drug delivery system (DDS) was tested with Nadolol®, a hydrophilic drug, and the release behaviours were studied at several temperatures. PVOH-b-PNVCL copolymers with an LCST of a few degrees above the biological temperature (37 °C), for example, PVOH180-b-PNVCL110 (LCST of 41 °C), are preferential, due to the slower release at 37 °C, but a faster release at temperatures that are a few degrees higher. The cytocompatibility of the gold@PVOH-b-PNVCL NPs against mouse fibroblastic L929 cells was evaluated via the MTS assay. Cellular uptake within MEL-5 human melanoma cells was studied by confocal laser scanning microscopy, fluorescence-activated cell sorting and TEM techniques and it showed that gold@PVOH-b-PNVCL NPs preferably accumulated within the cellular cytoplasm, with an incubation concentration and period-dependent uptake process. All these results corroborated a general utility of these thermo-responsive gold@PVOH-b-PNVCL NPs for drug delivery and controlled drug release. [less ▲]

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See detailThiophene derivatives with donor–π–acceptor structures for enhanced light-absorption properties and efficient cationic polymerization upon green-light irradiation
Telitel, Sofia; Ouhib, Farid ULg; Fouassier, Jean-Pierre et al

in Macromolecular Chemistry and Physics (2014), 215(16), 1514-1524

Positively charged thermoresponsive nanogels (NGs) are easily synthesized by precipitation polymerization of N-isopropyl­acrylamide and 2-dimethyl(aminoethyl)­methacrylate crosslinked with dendritic ... [more ▼]

Positively charged thermoresponsive nanogels (NGs) are easily synthesized by precipitation polymerization of N-isopropyl­acrylamide and 2-dimethyl(aminoethyl)­methacrylate crosslinked with dendritic polyglycerol. The NGs are characterized in terms of size, thermoresponsive properties, and Z potential. Their potential applications as drug delivery carriers are evaluated by the encapsulation and release of different anticancer drugs. As model drugs, doxorubicin and methotrexate are studied. [less ▲]

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See detailSynthesis of hybrid nanoparticles for theranostics
Liu, Ji ULg; Detrembleur, Christophe ULg; Duguet, Etienne et al

Conference (2014, May 28)

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See detailMultilayered chitosan-based fibers for skin regenaration applications
Croisier, Florence ULg; Detrembleur, Christophe ULg; Jérôme, Christine ULg

Poster (2014, May 26)

Chitosan is a natural polymer derived from the chitin of crustacean or mushroom shells, that intrinsically presents haemostatic, mucoadhesive, antimicrobial and immunostimulant properties. This ... [more ▼]

Chitosan is a natural polymer derived from the chitin of crustacean or mushroom shells, that intrinsically presents haemostatic, mucoadhesive, antimicrobial and immunostimulant properties. This polysaccharide has shown a great potential for biomedical and pharmaceutical applications, on account of its remarkable compatibility with physiological medium. Besides, it is degraded in a physiological environment into non-toxic products, which make chitosan an outstanding candidate for short- to medium-term applications. In this respect, nanometric fibers are highly interesting as their assembly mimics the skin extracellular matrix structure. Such nanofibrous materials can be prepared by electrospinning (ESP). This technique uses a high voltage to create an electrically charged jet of polymer solution or melt which leads to fibers formation. Depending on the polymer characteristics (a.o. molecular weight, solution viscosity and conductivity) and processing conditions (electric potential, distance between syringe-capillary and collection plate, concentration, flow rate), polymer fibers ranging from nanometers to a few microns in diameter can be obtained and subsequently used as potential scaffolds, a.o. to form a temporary, artificial extracellular matrix. In the present study, electrospinning technique was combined with layer-by-layer deposition method (LBL) - a well-known method for surface coating, based on electrostatic interactions - in order to prepare multilayered chitosan-based nanofibers. The antibacterial properties of the obtained material were then assessed, and the presence of a multilayered deposit was confirmed by several techniques. The multilayered chitosan-based nanofibers produced present great prospects for the preparation of new biomedical scaffolds - such as wound dressings that could improve skin regeneration. [less ▲]

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See detailLinear amphiphilic diblock copolymers of lactide and 2-dimethylaminoethyl methacrylate using bifunctional-initiator and one-pot approaches
Kryuchkov, Maksym A.; Detrembleur, Christophe ULg; Bazuin, Géraldine

in Polymer (2014), 55(10), 2316-2324

Linear amphiphilic diblock copolymers of polylactide (PLA) and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) were synthesized by atom transfer radical polymerization (ATRP) of DMAEMA followed by ring ... [more ▼]

Linear amphiphilic diblock copolymers of polylactide (PLA) and poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) were synthesized by atom transfer radical polymerization (ATRP) of DMAEMA followed by ring-opening polymerization (ROP) of LLA using the bifunctional initiator, 2′-hydroxyethyl 2-bromoisobutyrate. NMR showed that the resulting PLA block was racemic and a quaternization/precipitation technique showed that there were significant amounts of racemic PLA homopolymer. In addition, simultaneous ATRP of DMAEMA and ROP of l-lactide by tin octoate were conducted at varied temperatures, indicating 90 °C as a suitable compromise temperature; this one-pot process also led to racemization and P(L)LA homopolymer. The racemization was attributed to reversible deprotonation of LLA by the N(CH3)2 moiety of (P)DMAEMA and the PLA homopolymer impurity was related to in situ formation of lactoyl lactate (LA–LA) due to nucleophilic ring opening of lactide by the amino moieties of (P)DMAEMA. The methods presented can be useful for the preparation of PDMAEMA–b–PLA/PLA composites in a two-step process or in a single step, one-pot process. [less ▲]

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See detailSupercritical CO2 and polycarbonate based nanocomposites: A critical issue for foaming
Monnereau, Laure; Urbanczyk, Laetitia; Thomassin, Jean-Michel ULg et al

in Polymer (2014), 55(10), 2422-2431

Supercritical carbon dioxide readily induced foaming of various polymers. In that context, supercritical CO2 was applied to carbon nanotubes based polycarbonate nanocomposites to ensure their foaming ... [more ▼]

Supercritical carbon dioxide readily induced foaming of various polymers. In that context, supercritical CO2 was applied to carbon nanotubes based polycarbonate nanocomposites to ensure their foaming. Surprisingly, efficient foaming only occurs when low pressure is applied while at high pressure, no expansion of the samples was observed. This is related to the ability of supercritical carbon dioxide to induce crystallization of amorphous polycarbonate. Moreover, this behaviour is amplified by the presence of carbon nanotubes that act as nucleating agents for crystals birth. The thermal behaviour of the composites was analysed by DSC and DMA and was related to the foaming observations. The uniformity of the cellular structure was analysed by scanning electron microscopy (SEM). By saturating the polycarbonate nanocomposites reinforced with 1 wt% of MWNTs at 100 bar and 100 °C during 16 h, microcellular foams were generated, with a density of 0.62, a cell size ranging from 0.6 to 4 μm, and a cellular density of 4.1 × 1011 cells cm−3. The high ability of these polymeric foams to absorb electromagnetic radiation was demonstrated at low MWNT content as the result of the high affinity of the polycarbonate matrix for MWNTs, and therefore to the good MWNTs dispersion. [less ▲]

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See detailPoly(methyl methacrylate)/graphene oxide nanocomposites by a precipitation polymerization process and their dielectric and rheological characterization
Thomassin, Jean-Michel ULg; Trifkovic, Milana; Alkarmo, Walid et al

in Macromolecules (2014), 47(6), 2149-2155

We report a method for achieving controlled dispersion of graphene oxide (GO) in poly(methyl methacrylate) (PMMA) via the precipitation polymerization process in a water/ methanol mixture. GO acts as a ... [more ▼]

We report a method for achieving controlled dispersion of graphene oxide (GO) in poly(methyl methacrylate) (PMMA) via the precipitation polymerization process in a water/ methanol mixture. GO acts as a surfactant and adsorbs on the interface between polymerized PMMA particles and solvent mixture. Scanning electron and transmission electron microscopy confirmed that the precipitate consists of polymer particles (<1 μm) surrounded by the GO sheets. Compression molding of the precipitate yields a polymer nanocomposite with the GO organized into a regularly spaced 3D network which percolates at 0.2 wt % GO. Simple thermal reduction of the GO sheets dispersed in PMMA at relatively low temperature (210 °C) achieved electrical conductivity higher than 10−2 S/m at 0.4 wt % of GO. Parallel dielectric and rheological characterization demonstrated that the thermal reduction is a quite fast process without significant degradation of the polymer. The study should open up new opportunities in the design of GO-based polymer nanocomposites. [less ▲]

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See detail(Co)Polymerization of vinyl levulinate by cobalt-mediated radical polymerization and functionalization by ketoxime click chemistry
Allaoua, Imène; Eleuterio, Beatriz; Obadia, Mona M. et al

in Polymer Chemistry (2014), 5(8), 2973-2979

Vinyl levulinate is synthesized from levulinic acid by palladium-catalyzed vinyl exchange and is characterized by NMR and ESI-HRMS techniques. Homopolymerization of vinyl levulinate and random ... [more ▼]

Vinyl levulinate is synthesized from levulinic acid by palladium-catalyzed vinyl exchange and is characterized by NMR and ESI-HRMS techniques. Homopolymerization of vinyl levulinate and random copolymerization with vinyl acetate by cobalt-mediated radical polymerization affords well-defined ketone functionalized poly(vinyl ester)s. The impact of temperature, solvent and theoretical degree of polymerization on monomer conversion and control of the polymerization is studied by 1H NMR and size exclusion chromatography techniques. The ketoxime conjugation of O-benzylhydroxylamine with the pendant ketone functionality of poly(vinyl levulinate-co-vinyl acetate) is demonstrated. [less ▲]

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See detailGreen and bio-inspired processes for the functionalization of surfaces
Detrembleur, Christophe ULg

Conference (2014, March 18)

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See detailPrecision design of ethylene- and polar-monomer-based copolymers by organometallic-mediated radical polymerization
Kermagoret, Anthony ULg; Debuigne, Antoine ULg; Jérôme, Christine ULg et al

in Nature Chemistry (2014), 6(3), 179-187

The copolymerization of ethylene with polar monomers is a major challenge when it comes to the manufacture of materials with potential for a wide range of commercial applications. In the chemical industry ... [more ▼]

The copolymerization of ethylene with polar monomers is a major challenge when it comes to the manufacture of materials with potential for a wide range of commercial applications. In the chemical industry, free-radical polymerization is used to make a large proportion of such copolymers, but the forcing conditions result in a lack of fine control over the architecture of the products. Herein we introduce a synthetic tool, effective under mild experimental conditions, for the precision design of unprecedented ethylene- and polar-monomer-based copolymers. We demonstrate how an organocobalt species can control the growth of the copolymer chains, their composition and the monomer distribution throughout the chain. By fine tuning the ethylene pressure during polymerization and by exploiting a unique reactive mode of the end of the organometallic chain, novel block-like copolymer structures can be prepared. This highly versatile synthetic platform provides access to a diverse range of polymer materials. [less ▲]

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See detailGlucose-, pH- and thermo-responsive nanogels crosslinked by functional superparamagnetic maghemite nanoparticles as innovative drug delivery systems
Liu, Ji ULg; Detrembleur, Christophe ULg; Debuigne, Antoine ULg et al

in Journal of Materials Chemistry B (2014), 2(8), 1009-1023

Reversibly crosslinked (RCL) nanogels made of thermo-responsive poly(vinyl alcohol)-b-poly(Nvinylcaprolactam) copolymers were combined with maghemite nanoparticles and developed as new drug delivery ... [more ▼]

Reversibly crosslinked (RCL) nanogels made of thermo-responsive poly(vinyl alcohol)-b-poly(Nvinylcaprolactam) copolymers were combined with maghemite nanoparticles and developed as new drug delivery systems (DDS). The crosslinking was formed via boronate/diol bonding from the surfacefunctionalized superparamagnetic maghemite nanoparticles, endowing the DDS with thermo-, pH- and glucose-responsiveness. The capability to load a hydrophobic drug model Nile red (NR) within the RCL nanogels was evaluated, and stimuli-triggered drug release behaviours under different conditions were tested. Zero premature release behaviour was detected at physiological pH in the absence of glucose, whereas triggered release was observed upon exposure to acidic pH (5.0) and/or in the presence of glucose. In light of the superparamagnetic properties of the maghemite nanoparticles and RCL nanogels, magnetically-induced heating, MR imaging performance, as well as remotely magnetically-triggered drug release under alternating magnetic field (AMF), were investigated. Cytotoxicity against fibroblast-like L929 and human melanoma MEL-5 cell lines was assessed via the MTS assay. In vitro stimuli-triggered release of tamoxifen, a chemotherapeutic drug, was also studied within MEL-5 cell cultures under different conditions. These innovative RCL nanogels, integrating different stimuli-responsive components, hydrophobic chemotherapeutic moieties and also diagnostic agents together via reversible crosslinking, are promising new theranostic platforms. [less ▲]

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See detailGold nanorods coated with a thermo-responsive poly(ethylene glycol)-b-poly(N-vinylcaprolactam) corona as drug delivery systems for remotely near infrared-triggered release
Liu, Ji ULg; Detrembleur, Christophe ULg; De Pauw, Marie-Claire ULg et al

in Polymer Chemistry (2014), 5(3), 799-813

Poly(ethylene glycol)-b-poly(N-vinylcaprolactam) (PEG-b-PNVCL) copolymers are prepared from a PEG macro-chain transfer agent in DMF at 65 °C via reversible addition-fragmentation chain transfer (RAFT ... [more ▼]

Poly(ethylene glycol)-b-poly(N-vinylcaprolactam) (PEG-b-PNVCL) copolymers are prepared from a PEG macro-chain transfer agent in DMF at 65 °C via reversible addition-fragmentation chain transfer (RAFT) polymerization. The well-defined PEG114-b-PNVCL237 copolymer with a cloud point temperature of 39 °C is used for the formation of a thermo-responsive polymer corona on the surface of gold nanorods (GNRs) via a “grafting-to” approach. Thermo-responsiveness and thermo-dependent optical properties of the as-obtained GNR@PEG-b-PNVCL nanoparticles are studied with dynamic light scattering and UV/vis spectroscopy techniques. Near infrared (NIR)-induced heating of GNR@PEG-b-PNVCL is also explored in aqueous suspension under NIR laser irradiation (802 nm, up to 250 mW). The potential of these GNR@PEG-b-PNVCL nanoparticles to be used as smart drug delivery systems (DDS) is then studied. A hydrophilic drug model, Rhodamine ® B, is used to assess the guest loading capacity, and triggered release behaviours are then evaluated under conventional external heating or internal heating induced by remote NIR irradiation. Cytotoxicity evaluation of the GNR@PEG-b-PNVCL against the fibroblast-like L929 cell line is carried out via the MTS assay in order to confirm the improved biocompatibility of the GNRs after polymer coating. These thermo-responsive GNR@PEG-b-PNVCL nanoparticles are promising DDS that combine the chemotherapeutic and phototherapeutic functions. [less ▲]

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See detailPrecision synthesis of poly(ionic liquid)-based block copolymers by cobalt-mediated radical polymerization and preliminary study of their self-assembling properties
Coupillaud, Paul; Fèvre, Maréva; Wirotius, Anne-Laure et al

in Macromolecular Rapid Communications (2014), 35(4), 422-430

A poly(ionic liquid)-based block copolymer (PIL BCP), namely, poly(vinyl acetate)-b-poly(N-vinyl-3-butylimidazolium bromide), PVAc-b-PVBuImBr, is synthesized by sequential cobalt-mediated radical ... [more ▼]

A poly(ionic liquid)-based block copolymer (PIL BCP), namely, poly(vinyl acetate)-b-poly(N-vinyl-3-butylimidazolium bromide), PVAc-b-PVBuImBr, is synthesized by sequential cobalt-mediated radical polymerization (CMRP). A PVAc precursor is first prepared at 30 °C in bulk by CMRP of VAc, using bis(acetylacetonato)cobalt(II), Co(acac)2, and a radical source (V-70). Growth of PVBuImBr from PVAc-Co(acac)2 is accomplished by CMRP in DMF/MeOH (2:1, v/v). This PIL BCP self-assembles in the sub-micron size range into aggregated core–shell micelles in THF, whereas polymeric vesicles are observed in water, as evidenced by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Thin-solid sample cut from raw materials analyzed by TEM shows an ordered lamellar organization by temperature-dependent synchrotron small-angle X-ray scattering (SAXS). Anion exchange can be accomplished to achieve the corresponding PIL BCP with bis(trifluorosulfonyl)imide (Tf2N−) anions, which also gives rise to an ordered lamellar phase in bulk samples. A complete suppression of SAXS second-order reflection suggests that this compound has a symmetric volume fraction (f ≈ 0.5). SAXS characterization of both di- and triblock PIL BCP analogues previously reported also shows a lamellar phase of very similar behavior, with only an increase of the period by about 8% at 60 °C. [less ▲]

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