References of "Jérôme, Christine"
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See detailDevice-based controlled local delivery for the treatment of peritoneal pathologies
Riva, Raphaël ULg; Krier, Fabrice; Defrère, Sylvie et al

Poster (2013, August 18)

This contribution aims at reporting the developpment of a controlled drug delivery system (DDS) dedicated to the treatment of intra-peritoneal pathologies, especially endometriosis. At present time ... [more ▼]

This contribution aims at reporting the developpment of a controlled drug delivery system (DDS) dedicated to the treatment of intra-peritoneal pathologies, especially endometriosis. At present time, endometriosis is generally treated by daily oral absorption of drug with the purpose to improve the life quality of patients by the reduction of the pain caused by endometrial lesions. Nevertheless, deleterious side-effects, mainly infertility, are observed as a consequence of the important amount of absorbed active principle. One main advantage of controlled drug delivery devices, e.g. polymer implants, is to maintain sustained drug release over a prolonged period of time thereby eliminating fluctuations in the drug plasma concentration. Moreover, DDS allows a local release of the drug at a specific area, which significantly decreases the active principle concentration in the body and limits side-effects. The peritoneal cavity is a convenient site for the implantation of a DDS against endometriosis because large parts of lesion are localized in this region. At our knowledge, no application of an implant dedicated to the treatment of endometriosis is reported in the literature, whereas the local controlled release of an active principle presents several advantages compared to systemic administration. In this study, anastrozole (2,2’-[5-1H-1,2,4-triazole-1-yl-methyl)-1,3-phenylene]bis(2-methylpropiononitrile)), a well-known aromatase-inhibiting drug, was selected as active molecule. Typically, two non-biodegradable polymers were tested for the elaboration of an anastrozole loaded intra-peritoneal implant, namely polydimethylsiloxane (PDMS) and poly(ethylene-co-vinyl acetate) (EVA). As preliminary research, the ‘in vivo’ biocompatibility of PDMS and EVA in the intra-peritoneal cavity was confirmed by implantation of PDMS and EVA rod-shaped implants in rats. The kinetic of release was determined ‘in vitro’ and confirmed ‘in vivo’. Besides, the efficiency of the implants was improved by the addition of a polymer membrane, which allowed a controlled release of anastrozole over a period of 400 days. [less ▲]

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See detailMacroporous poly(ionic liquid)s and poly(acrylamide)s monoliths from CO2-in-water emulsion templates stabilized by sugar-based surfactants
Boyère, Cédric ULg; Favrelle, Audrey; Léonard, Alexandre ULg et al

in Journal of Materials Chemistry A (2013), 1(29), 8479-8487

Highly interconnected poly(acrylamide) (PAM) and poly(vinylimidazolium) (PVIm) porous monoliths were templated by carbon 10 dioxide-in-water (CO2/W) high internal phase emulsions (HIPEs), a toxic-solvent ... [more ▼]

Highly interconnected poly(acrylamide) (PAM) and poly(vinylimidazolium) (PVIm) porous monoliths were templated by carbon 10 dioxide-in-water (CO2/W) high internal phase emulsions (HIPEs), a toxic-solvent free process. A range of sugar-based fluorinated surfactants prepared by chemoenzymatic synthesis were used as emulsifiers. Both the concentration and the structure of the surfactants, especially the length of their CO2-philic part and of their spacer between the sugar head and the tail, were found to strongly affect the cellular structure and morphology of the PAM polyHIPEs, i.e. the size of pores and cells. A mannose derivative bearing a chain ranging from 6 to 10 perfluorinated carbons and a long spacer emerged as the best stabilizer, leading to a porous monolith with average pores and 15 cells sizes (about 2.6 1m and 5-10 1m, respectively) among the lowest reported for polyHIPEs produced from CO2/W emulsions. The same template then served for the preparation of the first macroporous poly(ionic liquid)s (PILs) polyHIPE by using 1-vinyl-3- ethylimidazolium bromide as monomer. Shrinkage of the final material was prevented by adjusting the divinylimidazolium crosslinker content. The resulting low density polyHIPE exhibits small spherical cells (~5 1m) connected by numerous small pores (~2 1m), confirming that the CO2/W HIPE templating methodology based on fluorinated glycosurfactants is a technique of choice for the 20 preparation of macroporous PILs. [less ▲]

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See detailElectrografting onto ITO substrates of poly(thiophene)-based micelles decorated by acrylate groups
Ouhib, Farid ULg; Desbief, Simon; Lazzaroni, Roberto et al

in Polymer Chemistry (2013), 4(15), 4151-4161

We report on a simple process for the chemisorption of poly(thiophene)-based block copolymers onto ITO substrates. Two poly(thiophene) block copolymers functionalized by acrylates on the second block are ... [more ▼]

We report on a simple process for the chemisorption of poly(thiophene)-based block copolymers onto ITO substrates. Two poly(thiophene) block copolymers functionalized by acrylates on the second block are prepared by the Grignard Metathesis (GRIM) process. The first block is composed of poly(3-hexylthiophene) (P3HT) and the second block is either a polythiophene bearing an acrylate group on each monomer unit (PAcET), or a polythiophene bearing both acrylate and poly(ethylene glycol) side chains (P(AcET-co-PEGET)). After characterizing their macromolecular parameters and optical properties, we investigate their ability to self-assemble into micelles in DMF solutions. This solvent is required for the electrografting procedure that is used for strongly anchoring the polymer to ITO. These micelles are expected to be formed by a P3HT core and a PAcET or P(AcET-co-PEGET) shell. When PEG side chains are present in the second block, the copolymer nicely self-assembles into micelles decorated by acrylates. Cathodic polarization of ITO induces chemisorption and polymerization of acrylate groups, leading to an adherent organized film of poly(thiophene)-based micelles. The optical absorption spectra show that the electrografted polymer chains have a degree of π-electron conjugation similar to that of crystalline P3HT films. In the absence of the PEG chains, the copolymer does not organize into micelles, due to the low stabilizing ability of the second block in DMF. [less ▲]

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See detailA novel strategy towards cyclic aliphatic (co)polyesters
Gao, Ch; Li, Y; Chi, J et al

in eXPRESS Polymer Letters (2013), 7(8), 690-702

This feature article focuses on a novel strategy towards macrocyclic (co)polyesters that combines controlled ring-opening polymerization of lactones initiated by a cyclic tin(IV) dialkoxide and ... [more ▼]

This feature article focuses on a novel strategy towards macrocyclic (co)polyesters that combines controlled ring-opening polymerization of lactones initiated by a cyclic tin(IV) dialkoxide and intramolecular cyclization by photocross- linking of pendant unsaturations next to the propagating sites. No linear species is ever involved in the polymerization and permanent cyclization steps, which allows higher molecular weight macrocycles to be prepared with high efficiency and no need for further purification. Moreover, this synthetic route is very flexible to the point where macrocyclic polyesters with more complex although well-defined architectures, such as tadpole-shaped and sun-shaped copolyesters, can be tailored. Synthesis of well-defined eight-shaped polyesters and twin tadpole-shaped copolymers has also been explored by using a spirocyclic tin(IV) alkoxides as an initiator. When functional lactones were introduced, the ‘click’ copper-mediated cycloaddition [3+2] reaction was utilized to make the eight-shaped and twin tadpole-shaped copolyesters amphiphilic. [less ▲]

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See detailCharacterization and optimization of GMO-based gels with long term release for intraarticular administration
Réeff, J.; Gaignaux, A.; Goole, J. et al

in International Journal of Pharmaceutics (2013), 451(1-2), 95-103

Osteoarthritis is characterized by slow degenerative processes in the articular cartilage within synovial joints. It could be interesting to develop a sustained-release formulation that could be effective ... [more ▼]

Osteoarthritis is characterized by slow degenerative processes in the articular cartilage within synovial joints. It could be interesting to develop a sustained-release formulation that could be effective on both pain/inflammation and restoration of mechanical integrity of the joint. Recently, an injectable system based on glycerol monooleate (GMO), containing clonidine as a model hydrophilic analgesic/anti-inflammatory drug and hyaluronic acid as a viscoelastic scaffold, showed promising potential as a biodegradable and biocompatible preparation to sustain the drug activity. However, drug release from the system is relatively fast (complete within 1 week) and the underlying drug release mechanisms not fully understood. The aims of this study were: (i) to significantly improve this type of local controlled drug delivery system by further sustaining clonidine release, and (ii) to elucidate the underlying mass transport mechanisms. The addition of FDA-approved inactive ingredients such as sodium oleate or purified soybean oil was found to be highly effective. The release rate could be substantially reduced (e.g., 50% release after 10 days), due to the increased hydrophobicity of the systems, resulting in slower and reduced water uptake and reduced drug mobility. Interestingly, Fick's second law of diffusion could be used to quantitatively describe drug release. [less ▲]

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See detailBiomimetic polymers
Clement, Benoît ULg; Vanslambrouck, Stéphanie ULg; Koole, Leo H. et al

Poster (2013, July 08)

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See detailPolymer/carbon based composites as electromagnetic interference (EMI) shielding materials
Thomassin, Jean-Michel ULg; Jérôme, Christine ULg; Pardoen, Thomas et al

in Materials Science & Engineering : R (2013), 74(7), 211-232

The extensive development of electronic systems and telecommunications has lead to major concerns regarding electromagnetic pollution. Motivated by environmental questions and by a wide variety of ... [more ▼]

The extensive development of electronic systems and telecommunications has lead to major concerns regarding electromagnetic pollution. Motivated by environmental questions and by a wide variety of applications, the quest for materials with high efficiency to mitigate electromagnetic interferences (EMI) pollution has become a mainstream field of research. This paper reviews the state-of-the-art research in the design and characterization of polymer/carbon based composites as EMI shielding materials. After a brief introduction, in Section 1, the electromagnetic theory will be briefly discussed in Section 2 setting the foundations of the strategies to be employed to design efficient EMI shielding materials. These materials will be classified in the next section by the type of carbon fillers, involving carbon black, carbon fiber, carbon nanotubes and graphene. The importance of the dispersion method into the polymer matrix (melt-blending, solution processing, etc.) on the final material properties will be discussed. The combination of carbon fillers with other constituents such as metallic nanoparticles or conductive polymers will be the topic of Section 4. The final section will address advanced complex architectures that are currently studied to improve the performances of EMI materials and, in some cases, to impart additional properties such as thermal management and mechanical resistance. In all these studies, we will discuss the efficiency of the composites/devices to absorb and/or reflect the EMI radiation. [less ▲]

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See detailEffect of clay modification on the mechanism of local deformations in PA6 nanocomposites
Dominkovics, Zita; Naveau, Elodie ULg; Jérôme, Christine ULg et al

in Macromolecular Materials and Engineering (2013), 298(7), 796-805

PA nanocomposites are prepared from clays organophilized with a phosphonium and an ammonium salt, and sodium montmorillonite is used as reference. The analysis of mechanical and micromechanical properties ... [more ▼]

PA nanocomposites are prepared from clays organophilized with a phosphonium and an ammonium salt, and sodium montmorillonite is used as reference. The analysis of mechanical and micromechanical properties of the composites reveal that several micromechanical deformation processes occur in the PA/MMT composites. The matrix cavitates at relatively small stress. Processes related to non-exfoliated clay structural units are initiated at larger stresses. Sound is emitted mainly by the fracture of particles, but debonding may also occur. The plastic deformation of the matrix dominates at larger stresses and deformations. The various local deformations are independent of each other and composite properties are not determined by silicate related processes but by the deformation of the matrix. [less ▲]

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See detailDesign of well-defined N-vinylamides based copolymers via organometalllic-mediated radical polymerization
Debuigne, Antoine ULg; Kermagoret, Anthony ULg; Fustin, Charles-André et al

Conference (2013, June 19)

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See detailEffect of head-to-head addition in vinyl acetate controlled radical polymerization: why is Co(acac)2-mediated polymerization so much better?
Morin, Aurélie N.; Detrembleur, Christophe ULg; Jérôme, Christine ULg et al

in Macromolecules (2013), 46(11), 4303-4312

The controlled polymerization of vinyl acetate has been recently achieved by several techniques, but PVAc with targeted Mn and low dispersity up to very high monomer conversions and high degrees of ... [more ▼]

The controlled polymerization of vinyl acetate has been recently achieved by several techniques, but PVAc with targeted Mn and low dispersity up to very high monomer conversions and high degrees of polymerization was only obtained with Co(acac)2 as controlling agent in the so-called CMRP, a type of organometallic mediated radical polymerization (OMRP). Other techniques (including ATRP, ITP, TERP, and RAFT/MADIX) have shown a more or less pronounced slowdown in the polymerization kinetics, which was attributed to the higher strength of the C−X bond between the radical PVAc chain and the trapping agent (X) in the dormant species and to a consequent slower reactivation after a less frequent head-to-head monomer addition. The reason for the CMRP exception is clarified by the present contribution. First, a detailed investigation by 1H, 13C and multiplicity-edited HSQC and DEPT-135 NMR of the PVAc obtained by CMRP, in comparison with a regular polymer made by free radical polymerization under the same conditions, has revealed that Co(acac)2 does not significantly alter the fraction of head-to-head sequences in the polymer backbone and that there is no accumulation of Co(acac)2-capped chains with a head-to-head ω end. Hence, both dormant chains (following the head-to-head and the head-to-tail monomer additions) must be reactivated at similar rates. A DFT study shows that this is possible because the dormant chains are stabilized not only by the C−Co σ bond but also by formation of a chelate ring through coordination of the ω monomer carbonyl group. The head-to-head dormant chain contains an inherently stronger C−Co bond but forms a weaker 6-membered chelate ring, whereas the weaker C−Co bond in the head-to-tail dormant chain is compensated by a stronger 5-membered chelate ring. Combination of the two effects leads to similar activation enthalpies, as verified by DFT calculations using a variety of local, gradient-corrected, hybrid and “ad hoc” functionals (BPW91, B3PW91, BPW91*, M06 and M06L). While the BDE(C−X) of model H-VAc−X molecules [X = Cl, I, MeTe, EtOC(S)S and Co(acac)2] are functional dependent, the BDE difference between head-to-head and head-to-tail dormant chain models is almost functional insensitive, with values of 5−9 kcal/mol for the ATRP, ITP and TERP models, 3−6 for the RAFT/MADIX model, and around zero for CMRP. [less ▲]

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See detailThe influence of foam morphology of multi-walled carbon nanotubes/poly(methyl methacrylate) nanocomposites on electrical conductivity
Tran, Minh Phuong ULg; Detrembleur, Christophe ULg; Alexandre, Michaël ULg et al

in Polymer (2013), 54(13), 3261-3270

Polymer/multi-walled carbon nanotubes (PMMA/MWNTs) nanocomposites foams are widely investigated during the last decade thanks to their potential applications as electromagnetic interferences shielding ... [more ▼]

Polymer/multi-walled carbon nanotubes (PMMA/MWNTs) nanocomposites foams are widely investigated during the last decade thanks to their potential applications as electromagnetic interferences shielding (EMI) materials. Electrical conductivity of the nanocomposite is a key parameter for these applications. In the frame of this work, we aim at establishing relationships between the foams morphology and their electrical conductivity. We therefore first design nanocomposite foams of various morphologies using supercritical carbon dioxide (scCO2) as physical foaming agent. The nanocomposites based on poly(methyl methacrylate) (PMMA) and different carbon nanotubes loadings are prepared by melt-mixing and foamed by scCO2 in various conditions of pressure, temperature and soaking time. The influence of these foaming conditions on the morphology of the foams (volume expansion, pore size, cell density, cell-wall thickness) is discussed. After measuring the electrical conductivity of the foams, we establish structure/properties relationships that are essential for further optimizations of the materials for the targeted application. [less ▲]

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