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See detailPreparation of multilayered chitosan-based nanofibers by combination of electrospinning and layer-by-layer deposition techniques
Croisier, Florence ULg; Aqil, Abdelhafid ULg; Detrembleur, Christophe ULg et al

Poster (2009, March)

By combining electrospinning technique and layer-by-layer deposition, we produced a new material made of multilayered, chitosan-based nanofibers. Layer-by-layer (LBL) is a well known method for surface ... [more ▼]

By combining electrospinning technique and layer-by-layer deposition, we produced a new material made of multilayered, chitosan-based nanofibers. Layer-by-layer (LBL) is a well known method for surface coating, based on electrostatic interactions. It enables the controllable deposition of a variety of polyions including synthetic and natural materials, with designable layer structure, defined wall thickness and size. Electrospinning (ESP) technique allows the fabrication of polymer fibers ranging from nanometers to a few microns in diameter, 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) (3). Mats of nanofibers produced by ESP display a very large surface area-to-volume ratio and high porosity with very small pore size. The nanometric scale of electrospun fibers also proves a positive effect on cellular growth, as fibers mats mimic extracellular matrix structure. The association of these two techniques with the use of biocompatible and biodegradable polymers such as chitosan, gives outstanding prospects in the field of biomedical applications, especially for the preparation of wound dressings, artificial skin or tissue engineering scaffolds. In the present study, a charged copolymer, poly(methylmethacrylate-block-methacrylic acid), was added to a poly(ε-caprolactone) or poly(D,L-lactide) solution before electrospinning in order to obtain charges on fibers surface. Oppositely charged polyelectrolytes – chitosan and poly(styrene sulfonate) or hyaluronic acid – were then alternately deposited on these aliphatic polyester fiber “cores” using LBL method. The aliphatic polyester core was also removed selectively to confirm the existence of a multilayered shell, obtaining hollow fibers. [less ▲]

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See detailPreparation of nanosized barium zirconate powder by precipitation in aqueous solution
Boschini, Frédéric ULg; Guillaume, Bernard ULg; Rulmont, André ULg et al

in Key Engineering Materials [=KEM] (2004), 264-268(Part 1-3), 2335-2338

Several ways were explored to synthesize barium zirconate by soft chemistry methods in aqueous solution. In the first method the synthesis of barium zirconate was initiated by urea decomposition, through ... [more ▼]

Several ways were explored to synthesize barium zirconate by soft chemistry methods in aqueous solution. In the first method the synthesis of barium zirconate was initiated by urea decomposition, through an homogeneous precipitation of barium and zirconium salts followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate[1]. A calcination at 1200degreesC during 2 hours gives rise to the formation of a pure barium zirconate phase. In the other methods, barium zirconate was synthesized, in one step without any thermal treatments, by precipitation in highly basic aqueous solutions containing barium and zirconium salts. The effect of the hydroxide concentration was discussed in relation to the barium zirconate phase formation, the particles size and the particles size distribution. For each powder, microstructural characterisations have been performed on sintered bodies in order to evaluate the influence of the thermal treatment on the final density. Dilatometric measurements have been also performed in order to quantify the densification process. Important informations were obtained by these techniques, as for example the existence of an internal porosity which severely limits the final density of the material, even if sintering was performed at high temperature. Thus a careful control of the heating profile seems to be necessary in order to produce dense materials. [less ▲]

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See detailPreparation of nanosized barium zirconate powder by thermal decomposition of urea in an aqueous solution containing barium and zirconium, and by calcination of the precipitate
Boschini, Frédéric ULg; Robertz, B.; Rulmont, André ULg et al

in Journal of the European Ceramic Society (2003), 23(16), 3035-3042

The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio ... [more ▼]

The synthesis of barium zirconate was initiated by urea induced homogeneous precipitation followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate. A calcination at 1200 degreesC during 2 h gives rise to the formation of a pure barium zirconate phase. Microstructural characterisations have been performed in order to evaluate the sintering behaviour. Dilatometric measurements, coupled with scanning electron microscopy analyses clearly indicate that barium carbonate decomposition process leads to the formation of internal porosity which severely limits the density of the material, even if a sintering was performed at 1500 degreesC. A careful control of the heating profile seems to be necessary in order to produce dense materials. (C) 2003 Elsevier Ltd. All rights reserved. [less ▲]

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See detailPreparation of new radiation-curing binders
Detrembleur, Christophe ULg; Weikard, Jan; Greszta-Franz, Dorota et al

Patent (2008)

Process for preparing binders including reacting A) one or more NCO-functional compounds containing uretdione groups with B) one or more compounds containing groups capable of participating in ... [more ▼]

Process for preparing binders including reacting A) one or more NCO-functional compounds containing uretdione groups with B) one or more compounds containing groups capable of participating in polymerization reaction with ethylenically unsaturated compounds on exposure to actinic radiation, and contain isocyanate-reactive groups, followed by C) reaction with one or more hydroxyl-containing compounds other than B), wherein at least one of these compounds has an OH functionality of>=2, D) in the presence of one or more compounds containing phenoxide groups, as catalysts, and E) optionally auxiliaries and additives, where the reaction with compounds of component C); proceeds at least proportionally with the formation of allophanate groups and where and including binders containing allophanate groups and groups capable of participating in a polymerization reaction with ethylenically unsaturated compounds on exposure to actinic radiation, and optionally also contain NCO-reactive groups. The binders are used in coating compositions used to coat substrates. [less ▲]

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See detailPreparation of new radiation-curing binders
Detrembleur, Christophe ULg; Weikard, Jan; Greszta-Franz, Dorota et al

Patent (2005)

Process for preparing binders including reacting A) one or more NCO-functional compounds containing uretdione groups with B) one or more compounds containing groups capable of participating in ... [more ▼]

Process for preparing binders including reacting A) one or more NCO-functional compounds containing uretdione groups with B) one or more compounds containing groups capable of participating in polymerization reaction with ethylenically unsaturated compounds on exposure to actinic radiation, and contain isocyanate-reactive groups, followed by C) reaction with one or more hydroxyl-containing compounds other than B), wherein at least one of these compounds has an OH functionality of >=2, D) in the presence of one or more compounds containing phenoxide groups, as catalysts, and E) optionally auxiliaries and additives, where the reaction with compounds of component C); proceeds at least proportionally with the formation of allophanate groups and where and including binders containing allophanate groups and groups capable of participating in a polymerization reaction with ethylenically unsaturated compounds on exposure to actinic radiation, and optionally also contain NCO-reactive groups. The binders are used in coating compositions used to coat substrates [less ▲]

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See detailPreparation of pH-sensitive star-shaped aliphatic polyesters as precursors of polymersomes
Riva, Raphaël ULg; Lazzari, Wenda; Billiet, Leen et al

in Journal of Polymer Science. Part A, Polymer Chemistry (2011), 49(7), 1552-1563

The synthesis of a new pH-sensitive amphiphilic A2B mikto-arm star-shaped aliphatic copolyester (with A = PCL and B = tertiary amine-bearing PCL) with two hydrophobic arms and one hydrophilic arm when ... [more ▼]

The synthesis of a new pH-sensitive amphiphilic A2B mikto-arm star-shaped aliphatic copolyester (with A = PCL and B = tertiary amine-bearing PCL) with two hydrophobic arms and one hydrophilic arm when protonated at pH = 5.5. The copper mediated azide-alkyne cycloaddition was used for the synthesis of the star copolyester and to impart the pH sensitivity to the hydrophilic arm by grafting of tertiary amine groups onto azide bearing PCL chain. The formation of polymersomes in water at pH 5 was assessed by DLS and TEM analyses. [less ▲]

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See detailPreparation of poly(D,L)lactide microspheres and their clinical applications as a convenient embolic material
Grandfils, Christian ULg; Flandroy, P; Nihant, N et al

Conference (1990, September)

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See detailPreparation of poly(D,L)lactide microspheres and their clinical applications as a convenient embolic material
Grandfils, Christian ULg; Flandroy, Pierre; Nihant, Nicole et al

in Journal de Pharmacie de Belgique (1990), 6

Owing to their shape, accurately calibrated microspheres appear to be very suitable material for distal embolization. Moreover, the biocompatible (D,L) polylactide (PLA) microspheres possess two other ... [more ▼]

Owing to their shape, accurately calibrated microspheres appear to be very suitable material for distal embolization. Moreover, the biocompatible (D,L) polylactide (PLA) microspheres possess two other valuable advantages: easy adjustment of their biodegradation rate, and incorporation of chemotherapeutic agents during their production. The authors describe the preparation of these (D,L) PLA microspheres and their clinical applications as a preliminary step to arterial chemoembolization. [less ▲]

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See detailPreparation of poly(D,L)lactide microspheres by emulsion-solvent evaporation and their clinical applications as a convenient embolic material
Grandfils, Christian ULg; Flandroy, P; Nihant, N et al

in Journal of Biomedical Materials Research (1992), 26

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See detailPreparation of poly(D,L-lactide) nanoparticles assisted by amphiphilic poly(methyl methacrylate-co-methacrylic acid) copolymers
Gautier, Sandrine; Grudzielski, Nathalie; Goffinet, Gerhard ULg et al

in Journal of Biomaterials Science. Polymer Edition (2001), 12(4), 429-450

When co-precipitated with amphiphilic copolymers from DMSO, poly(D,L-lactide) (PLA) can be readily converted into stable sub-200 nm nanoparticles by addition of an aqueous phase, free of any polymeric ... [more ▼]

When co-precipitated with amphiphilic copolymers from DMSO, poly(D,L-lactide) (PLA) can be readily converted into stable sub-200 nm nanoparticles by addition of an aqueous phase, free of any polymeric stabilizers such as poly(vinyl alcohol) or Poloxamer. In this work, the ability of random poly(methyl methacrylate-co-methacrylic acid) copolymers (PMMA-co-MA) to stabilize PLA nanoparticles was demonstrated, and the properties of PLA/PMMA-co-MA nanoparticles were investigated. When co-precipitated with PMMA-co-MA, PLA was totally converted into nanoparticles using a polymer concentration in DMSO (Cp) below 17.6 mg ml(-1), and a PMMA-co-MA proportion above a critical value depending on the content of MA repeating units (X). For instance, the lowest PMMA-co-MA proportion required was 0.9 mg mg(-1) PLA for X = 12%, and 0.5 mg mg(-1) PLA for X = 25% (for C(PLA) = 16 mg ml(-1) DMSO). The nanoparticle diameter was essentially independent of X, the proportion of PMMA-co-MA, and the PLA molecular weight, except for oligomers for which the nanoparticle diameter was smaller. It decreased when the organic phase was diluted (126 +/- 13 nm for Cp = 17.6 mg ml(-1), and 81 +/- 5 nm for C(P) = 5.6 mg ml(-1)). The time-dependence of the stability and the degradation of PLA/PMMA-co-MA nanoparticles was discussed. One of the main advantages of this technique is the ability to control surface properties and to bring functional groups to otherwise non-functionalized PLA nanoparticles. To illustrate this, a conjugate of PMMA-co-MA25 and biotin was synthesized, and used to prepare biotinylated nanoparticles that could be detected by fluorescence and transmission electron microscopy after infiltration into ligatured rat small intestine. [less ▲]

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See detailPreparation of poly(epsilon-caprolactone) brushes at the surface of conducting substrates
Voccia, Samuel; Bech, Loïc; Gilbert, Bernard ULg et al

in Langmuir (2004), 20(24), 10670-10678

This paper reports on the preparation of polyester brushes at the surface of electrically conducting materials. A two-step strategy has been worked out that consists of the electropolymerization of an ... [more ▼]

This paper reports on the preparation of polyester brushes at the surface of electrically conducting materials. A two-step strategy has been worked out that consists of the electropolymerization of an acrylate under a cathodic potential, such that the polyacrylate layer is chemisorbed at the surface. In a second step, either preformed poly(epsilon-caprolactone) chains are grafted onto the polyacrylate sublayer or the ring-opening polymerization of epsilon-caprolactone is initiated from it. [less ▲]

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See detailPreparation of polyaniline-modified local clay and study of its sorption capacity
Benhebal, Hadj; Chaid, Messaoud; Léonard, Angélique ULg et al

in Journal of Nanostructure in Chemistry (2014), 4(98), 6

Clay minerals are frequently used in adsorption processes with aqueous solution; it was found that the adsorption properties of clays change when the samples are modified. In this context, polyaniline ... [more ▼]

Clay minerals are frequently used in adsorption processes with aqueous solution; it was found that the adsorption properties of clays change when the samples are modified. In this context, polyaniline-modified clay nanocomposite (at 10 %) was prepared by in situ polymerization processes. The structural and morphological characteristics of the synthesized material are systematically examined by X-ray diffraction, scanning electron microscopy, thermo-gravimetry, differential scanning calorimetry and infrared spectroscopy techniques. The adsorption property of the modified clay was evaluated for the removal of a reactive dye (methylene blue) from aqueous solution at room temperature (25 C) via batch adsorption. [less ▲]

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See detailPreparation of reactive surfaces by electrografting
Jérôme, Christine ULg; Gabriel, Sabine ULg; Voccia, Samuel et al

in Chemical Communications (2003), (19), 2500-2501

The electrografting process has been applied to a new monomer in order to induce reactivity to the surface of various conducting substrates which are then appropriate for the anchoring of a large variety ... [more ▼]

The electrografting process has been applied to a new monomer in order to induce reactivity to the surface of various conducting substrates which are then appropriate for the anchoring of a large variety of molecules (catalysts, proteins, amino-polymers etc.). [less ▲]

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See detailPreparation of reproducible alkaline phosphatase-antibody conjugates for enzyme immunoassay using a heterobifunctional linking agent
Jeanson, Antoinette; Cloes, Jean-Michel; Bouchet, Mireille et al

in Analytical Biochemistry (1988), 172(2), 392-396

Conjugates of alkaline phosphatase (AP) and mouse monoclonal immunoglobulins G (IgG) were prepared by means of the heterobifunctional linker, N-succinimidyl 3-(2-pyridyldithio)-propionate. The efficiency ... [more ▼]

Conjugates of alkaline phosphatase (AP) and mouse monoclonal immunoglobulins G (IgG) were prepared by means of the heterobifunctional linker, N-succinimidyl 3-(2-pyridyldithio)-propionate. The efficiency of such conjugates can be improved by optimizing the degree of substitution of IgG and AP. We have determined conditions yielding better performing conjugates than those synthesized by methods described previously. Moreover, the results obtained with the technique presented here are quite reproducible with all four monoclonal antibodies tested. [less ▲]

Detailed reference viewed: 62 (1 ULg)