References of "Jérôme, Christine"
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See detailElectrografting of acrylate monomer, versatile method for coatings and thin films technologies
Aqil, Abdelhafid ULg; Jérôme, Christine ULg

Conference (2014, September)

Among the high research activity in the area of surface modification, electrografting is a very powerful and effective technique. When conducted under appropriate conditions of solvent and cathodic ... [more ▼]

Among the high research activity in the area of surface modification, electrografting is a very powerful and effective technique. When conducted under appropriate conditions of solvent and cathodic potential, the electropolymerization of (meth)acrylic monomers results in the chemisorption of the polymer on the conducting surface. This one-step electrografting technique is very easily implemented, can be applied to a wide range of (semi)-conducting surfaces by keeping the same chemistry and requires commonly used, readily available (meth)acrylate monomers. The wide variety of acrylic monomers suitable for this process makes available a broad range of surface properties including bactericidal, superhydrophobic and proteins repellent coatings. Electrografted smart coatings able to respond to external stimuli are also of interest particularly for sensors and actuators. [less ▲]

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See detailPolymer topology revealed by ion mobility coupled with mass spectrometry
Morsa, Denis ULg; Defize, Thomas ULg; Dehareng, Dominique ULg et al

in Analytical Chemistry (2014), 86(19), 96939700

Hyperbranched and star shaped polymers have raised tremendous interests because of their unusual structural and photochemical properties which provide them potent applications in various domains, namely ... [more ▼]

Hyperbranched and star shaped polymers have raised tremendous interests because of their unusual structural and photochemical properties which provide them potent applications in various domains, namely in the biomedical field. In this context, the development of adequate tools aiming to probe particular three-dimensional features of such polymers is of crucial importance. In this present work, ion mobility coupled with mass spectrometry was used to experimentally derive structural information related to cationized linear and star-shaped poly-ε-caprolactones as a function of their charge state and chain length. Two major conformations were observed and identified using theoretical modeling: (1) near spherical conformations whose size is invariant with the polymer topology for long and lightly charged chains and (2) elongated conformations whose size varies with the polymer topology for short and highly charged chains. These conformations were further confirmed by collisional activation experiments based on the ejection thresholds of the coordinated cations that vary according to the elongation amplitude of the polymer chains. Finally, a comparison between solution and gas-phase conformations highlights a compaction of the structure with a loss of specific chain arrangements during the ionization and desolvation steps of the electrospray process, fueling the long-time debated question related to the preservation of the analyte structure during the transfer into the mass spectrometer. [less ▲]

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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 ▲]

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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 detailRole of non-polyQ regions on the aggregation process by polyQ proteins into amyloid fibrils
Huynen, Céline ULg; Willet, Nicolas ULg; Buell, Alexander K et al

Poster (2014, July 28)

Nine neurodegenerative disorders, referred to as polyglutamine diseases and including Huntington’s disease, are associated with the abnormal expansion of a polyglutamine tract inside nine unrelated ... [more ▼]

Nine neurodegenerative disorders, referred to as polyglutamine diseases and including Huntington’s disease, are associated with the abnormal expansion of a polyglutamine tract inside nine unrelated proteins. This polyQ expansion is thought to be the major determinant in the development of neurotoxicity, triggering protein aggregation into amyloid fibrils. A large body of evidence however indicates that non-polyQ regions modulate the aggregation process triggered by polyQ expansions. The interplay between the polyQ tract and non-polyQ regions is complex and still not fully understood. In order to better understand it, we previously designed and characterized model polyQ proteins made of the beta-lactamase BlaP and a 23, 30, 55 or 79Q tract inserted in position 197 or 216. These chimeras recapitulate the aggregation properties of polyQ disease-associated proteins: there is a Q threshold for the formation of amyloid fibrils, and above the threshold, the longer the polyQ, the faster the aggregation. Moreover, the structure of BlaP (native or unfolded) and the position of insertion of the polyQ tract (197 versus 216) influence their aggregation properties. In this work, (i) we will discuss the role of the conformation of the host protein, BlaP, and of the location of the polyQ within BlaP on the different phases of amyloid fibril formation, the nucleation and elongation steps, using mainly quartz crystal microbalance (QCM), atomic force microscopy (AFM) and dynamic light scattering (DLS); and (ii) we will investigate the precise aggregation threshold and the modulating role of the N- and C-terminal polyQ flanking sequences in position 197 of BlaP by creating and characterizing new chimeras containing intermediate length polyQ tracts in position 197, or polyQ tracts inserted between two cleavage sites in position 197, respectively. Our results highlight a linear dependence of the polyQ length on the elongation rate whatever the insertion site and the conformation of BlaP. These two parameters however drastically influence the ability of a polyQ tract to trigger the nucleation and the elongation steps of amyloid fibril formation. Finally, we observed that the propensity to form amyloid fibrils and its rate seems to be largely dependent on the polyQ length and on the polyQ flanking sequences. Altogether our results contribute to identify the important species and elements (polyQ or non-polyQ regions, monomers, oligomers or fibrils) during the aggregation process into amyloid fibrils to interfere with the latter associated with neurotoxicity. [less ▲]

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See detailMicellization of PEO-b-polyphosphate for drug delivery applications
Vanslambrouck, Stéphanie ULg; Clément, Benoit; Riva, Raphaël ULg et al

Conference (2014, July 11)

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See detailSupercritical CO2, impregnation to prepare drug-loaded implants: inpregantion of anti-inflammatory drugs into sutures
Champeau, Mathilde; Tassaing, Thierry; Thomassin, Jean-Michel ULg et al

Conference (2014, July 10)

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See detailSynthesis of degradable polyphosphoester copolymers for templating calcium carbonate drug delivery carriers
Ergül, Zeynep ULg; Debuigne, Antoine ULg; Calvignac, Brice et al

Conference (2014, July 09)

Degradable acid bearing polyphosphoester (PPE) copolymers were prepared by combination of organocatalyzed ring opening polymerization and click chemistry. Their solution behavior and ability to complex ... [more ▼]

Degradable acid bearing polyphosphoester (PPE) copolymers were prepared by combination of organocatalyzed ring opening polymerization and click chemistry. Their solution behavior and ability to complex calcium ions were studied as well as their capacity to template CaCO3 particles dedicated to drug delivery. [less ▲]

Detailed reference viewed: 84 (21 ULg)
See detailFormation of nanogels by cobalt-mediated radical polymerizatin (CMRP) in the presence of divnylic cross-linking agents
Weiss-Maurin, Mathilde ULg; Jérôme, Christine ULg; Taton, Daniel et al

Poster (2014, July 03)

Cobalt-Mediated Radical Polymerization (CMRP) is one of the most efficient techniques to form sequenced copolymers between monomers of very different reactivities(e.g. vinyl acetate and acrylonitrile ... [more ▼]

Cobalt-Mediated Radical Polymerization (CMRP) is one of the most efficient techniques to form sequenced copolymers between monomers of very different reactivities(e.g. vinyl acetate and acrylonitrile). CMRP is used here to synthesize nanogels of vinylic monomers (either vinyl acetate or ionic liquid monomers) using different concentrations of cross-linking agent (divinyl adipate, or divinyl imidazolium). The aim is to determine the difference in structure of the nanogels, in order to use them for the preparation of star-like and/or core-shell structures. [less ▲]

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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)

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See detailCollapsing and reswelling kinetics of thermoresponsive polymers on surfaces: a matter of confinement and constraints
Willet, Nicolas ULg; Gabriel, Sabine ULg; Jérôme, Christine ULg et al

in Soft Matter (2014), 10

We report on the collapsing and reswelling ability of grafted poly(methyl vinyl ether) chains of different molecular architectures. In order to study the influence of constraints and confinement of the ... [more ▼]

We report on the collapsing and reswelling ability of grafted poly(methyl vinyl ether) chains of different molecular architectures. In order to study the influence of constraints and confinement of the chains, the polymer was grafted onto AFM tips, as a model of a curved nano-sized surface, and onto macroscopic silicon substrates for comparison purposes. AFM-based force spectroscopy experiments were performed to characterise at the nanoscale the temperature-dependent collapsing process and the reversibility to the swollen state on both substrates. The reversible character of the thermoresponsive transition and its kinetics were shown to greatly depend on the polymer architecture and the constraints encountered by the chains. [less ▲]

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See detailStructure-morphology relationship of polyphosphate containing polymer micelles
Vanslambrouck, Stéphanie ULg; Clément, Benoit; Riva, Raphaël ULg et al

Conference (2014, June 18)

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See detailIn situ FTIR micro-spectroscopy to investigate polymeric fibers under supercritical carbon dioxide: CO2 sorption and swelling measurements
Champeau, Mathilde; Thomassin, Jean-Michel ULg; Jérôme, Christine ULg et al

in Journal of Supercritical Fluids (2014), 90

An original experimental set-up combining a FTIR (Fourier Transformed InfraRed) microscope with a high pressure cell has been built in order to analyze in situ and simultaneously the CO2 sorption and the ... [more ▼]

An original experimental set-up combining a FTIR (Fourier Transformed InfraRed) microscope with a high pressure cell has been built in order to analyze in situ and simultaneously the CO2 sorption and the polymer swelling of microscopic polymer samples, such as fibers, subjected to supercritical carbon dioxide. Thanks to this experimental set-up, we have determined as a function of the CO2 pressure (from 2 to 15 MPa) the CO2 sorption and the polymer swelling at T = 40 °C of four polymer samples, namely PEO (polyethylene oxide), PLLA (poly-l-lactide acid), PET (polyethylene terephtalate) and PP (polypropylene). The quantity of CO2 sorbed in all the studied polymers increases with pressure. PEO and PLLA display a significant level of CO2 sorption (20 and 25% respectively, at P = 15 MPa). However, we observe that a lower quantity of CO2 can be sorbed into PP and PET (7 and 8% respectively, at P = 15 MPa). Comparing their thermodynamic behaviors and their intrinsic properties, we emphasize that a high CO2 sorption can be reach if on one hand, the polymer is able to form specific interaction with CO2 in order to thermodynamically favor the presence of CO2 molecules inside the polymer and on the other, displays high chains mobility in the amorphous region. PLLA and PEO fulfilled these two requirements whereas only one property is fulfilled by PET (specific interaction with CO2) and PP (high chains mobility). Finally, we have found that for a given CO2 sorption, the resulting swelling of the polymer depends mainly on its crystallinity. [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)

Detailed reference viewed: 28 (7 ULg)
See detailTemplating calcium carbonate drug delivery carriers based on polyphosphoester copolymers
Ergül, Zeynep ULg; Debuigne, Antoine ULg; Caalvignac, Brice et al

Poster (2014, May 27)

The design of drug delivery systems (DDS) often requires biodegradable and biocompatible materials that allow safe retention and controlled release of the drug. In this respect, CaCO3 particles are ... [more ▼]

The design of drug delivery systems (DDS) often requires biodegradable and biocompatible materials that allow safe retention and controlled release of the drug. In this respect, CaCO3 particles are appropriate drug carriers that have excellent properties such as low density, high specific surface areas and porosity for drugs and proteins encapsulation. Here, hyaluronic acid usually used for templating CaCO3 particles was substituted by a degradable synthetic copolymer based on PPE. The latter is a promising candidate due to its biocompatibility, biodegradability and the low toxicity of its degradation products such as phosphates. We also introduced acid functions on the PPE segment in order to enhance its calcium affinity and ability to tune the morphology of the CaCO3 particles. The butynyl phospholane (BYP) polymerization was initiated from poly(ethylene oxide) PEO-OH by organocatalyzed ring opening polymerization (ROP) [2] followed by UV catalyzed thiol-yne addition of 3-mercaptopropionoic acid onto the alkyne functions. CaCO3 particles were then generated in the presence of the copolymer following a procedure inspired from . Well-defined PPE copolymers bearing pendant alkynyl groups, i.e. PEO-b-PBYP (Ð <1.1), were obtained by organocatalyzed ROP of BYP initiated at 0°C from PEO-OH (Scheme 1). The copolymer was then reacted under UV with 3-mercaptopropionoic acid in order to introduce carboxylic acid functions along the PPE backbone by thiol-yne reaction. NMR analyses confirmed that full functionalization was reached after 2h. The high density of acid moieties in PEO-b-PBYP(COO-)2 is supposed to facilitate the Ca2+ complexation. The solution behavior and self-assembly of PEO-b-PBYP(COO-)2 in water was investigated by DLS with and without Ca+2 at different pH. Finally, stoichiometric amounts of CaCl2 and Na2CO3 were mixed in water containing the PEO-b-PBYP(COO-)2 which strongly influences the size of the CaCO3 particles (~1.5 µm). The acid-bearing PPE-based copolymers were successfully prepared and used as templating agents for the synthesis of CaCO3 particles. [less ▲]

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See detailSynthesis of a glucosamine labeled amphiphilic polymer for drug delivery application
Riva, Raphaël ULg; Boyère, Cédric; Debuigne, Antoine ULg et al

Poster (2014, May 27)

Detailed reference viewed: 54 (6 ULg)
See detailComprehensive study of chemically cross-linked PCLs presenting one-way and two-way shape memory properties
Defize, Thomas ULg; Riva, Raphaël ULg; Thomassin, Jean-Michel ULg et al

Poster (2014, May 26)

Poly(ε-caprolactone) (PCL), a semi-crystalline polymer, is one of the most widely studied polymers for the development of shape memory materials when chemically cross-linked. PCL presents several ... [more ▼]

Poly(ε-caprolactone) (PCL), a semi-crystalline polymer, is one of the most widely studied polymers for the development of shape memory materials when chemically cross-linked. PCL presents several advantages such as a melting transition temperature close to human body temperature, a high biocompatibility and is (bio)degradable. So, this polymer is highly relevant for both biomedical devices such as stents or resorbable suture wires and also for degradable packaging. However, after cross-linking, the material can not be reprocessed, preventing any reuse/recycling of the material. One of the purposes of this work is to find a solution to this major drawback, which would then allow, for example, to reshape packaging films after use or to recycle trimmings remaining after fabrication. Amongst current trends in the design of new polymer and composite materials, the use of organic reactions that are able to create and reversibly disrupt chemical bonds upon an external stimulus (temperature, irradiation,…) is currently gaining more and more attention as it can lead to applications in various areas such as remendable materials, drug delivery systems, stimulus-degrading materials or recyclable materials. Amongst all the reversible links described in the literature, thermally (4+2) reversible cycloadditions present interesting features such as the creation of robust bonds and well defined reversibility conditions. As an example, the application of furan/maleimide adducts as covalent link, which cycloreversion is largely favored in the range of temperature (90-120°C), is widely reported. Typically, PCL-based shape memory materials have been prepared by mixing a stoichiometric amount of diene-bearing and maleimide-bearing PCLs in a twin-screw mini-extruder at a temperature at which DA cycloaddition is largely disfavored, followed by the curing of the blend above the melting temperature to improve the kinetic of DA adduct formation. The shape memory properties of the materials have been studied by cyclic tensile thermomechanical analysis. As cross-linked PCLs are knowned to exhibit one-way and two-way shape memory properties, a comprehensive study of the shape memory of these materials has been carried out. Unfortunately, creep from shape memory cycle to cycle was observed in DMA for the furan/maleimide sample, certainly due to the reversibility of the adduct. In order to limit this creep effect, the substitution of the furan/maleimide adduct by a more stable adduct is required. The anthracene/maleimide system was tested because this adduct is more stable under stress than the furan/maleimide one. This contribution aims at reporting a complete study of one-way and two-way shape memory properties of the PCL cross-linked by anthracene/maleimide adduct. The shape memory properties of this material have been assessed by DMA and DSC experiments. [less ▲]

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