References of "Gilbert, Bernard"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailCharged poly(D,L-lactide) nanofibers: towards customized surface properties
Croisier, Florence ULg; Aqil, Abdelhafid ULg; Malherbe, Cédric ULg et al

in Macromolecular Symposia (2011), 309/310(1), 20-27

Surface-charged nanofibers were prepared by electrospinning technique (ESP). For this purpose, a copolymer bearing carboxylic acid functions was added to a poly(D,L-lactide) solution just before ESP ... [more ▼]

Surface-charged nanofibers were prepared by electrospinning technique (ESP). For this purpose, a copolymer bearing carboxylic acid functions was added to a poly(D,L-lactide) solution just before ESP process. In a basic medium, negative charges were therefore revealed on fiber surface. By deposition of positively charged particles or polyelectrolytes, surface properties of the fibers could be tailor-made for a specific application. This versatile method can, for example, be applied to the preparation of new biomedical scaffolds. [less ▲]

Detailed reference viewed: 50 (19 ULg)
Full Text
Peer Reviewed
See detailGenetically engineered polypeptides as a new tool for inorganic nano-particles separation in water based media
Vreuls, Christelle ULg; Genin, Alexis ULg; Zocchi, Germaine ULg et al

in Journal of Materials Chemistry (2011), 21

The present paper relates a method for the separation of an insoluble inorganic powder out of a mixture of several insoluble powders with different chemical compositions, using genetically engineered ... [more ▼]

The present paper relates a method for the separation of an insoluble inorganic powder out of a mixture of several insoluble powders with different chemical compositions, using genetically engineered inorganic binding peptides (GEPI). GEPI are small peptides that recognize and specifically bind an inorganic solid material. This GEPI is anchored to magnetic beads for easy recovery of the powder of interest from the mixture. [less ▲]

Detailed reference viewed: 76 (25 ULg)
See detailAbout Accessible Acidity Level in Ionic Liquids
Robert, Thierry ULg; Gilbert, Bernard ULg

Scientific conference (2011, April 27)

Detailed reference viewed: 31 (8 ULg)
See detailCaractérisation et vieillissement accéléré de pigments de bleu de Prusse synthétisés selon les méthodes de préparation anciennes et modernes
Samain, Louise ULg; Lauricella, Melina; Silversmit, Geert et al

Conference (2011, April 11)

Detailed reference viewed: 79 (14 ULg)
See detailFading of modern Prussian blue pigments in linseed oil medium
Samain, Louise ULg; Silversmit, Geert; Sanyova, Jana et al

Poster (2011, February 04)

Detailed reference viewed: 20 (6 ULg)
Full Text
Peer Reviewed
See detailFading of modern Prussian blue pigments in linseed oil medium
Samain, Louise ULg; Silversmit, Geert; Sanyova, Jana et al

in Journal of Analytical Atomic Spectrometry [=JAAS] (2011), 26(5), 930

The fading of modern laboratory-synthesized and commercial Prussian blue, iron(III) hexacyanoferrate(II), based pigments in a linseed oil medium during exposure to light has been investigated. The ... [more ▼]

The fading of modern laboratory-synthesized and commercial Prussian blue, iron(III) hexacyanoferrate(II), based pigments in a linseed oil medium during exposure to light has been investigated. The Prussian blue pigments were painted from linseed oil, as a pure pigment and mixed with white lead, (PbCO3)2Pb(OH)2, zinc white, ZnO, or titanium white, TiO2, pigment. The samples were subjected to accelerated ageing for 800 hours and the light fastness of the Prussian blue pigment was evaluated by reference to blue wool standards. Pure Prussian blue is extremely light fast whilst it strongly fades when mixed with a white pigment, especially with lead white or zinc oxide. The painted samples were studied by UV-visible, iron K-edge X-ray absorption, iron-57 transmission Mössbauer, and attenuated total reflectance infrared spectroscopy. X-ray absorption results reveal a decrease in the iron coordination number in aged samples in the presence of white pigment. The Mössbauer spectra of the pure Prussian blue and the unaged and aged mixtures of Prussian blue and lead white or zinc oxide at 1:100 and 1:10 dilution ratios, respectively, indicate the presence of iron(II) and iron(III) in a ratio close to one as expected for the bulk stoichiometric KFeIII[FeII(CN)6]; no change in the spectral parameters was observed upon ageing. Combined with the X-ray near edge absorption and infrared studies, these results suggest reduction of the surface iron ions in the Prussian blue with ageing upon exposure to light. [less ▲]

Detailed reference viewed: 78 (14 ULg)
Full Text
Peer Reviewed
See detailStraightforward synthesis of conductive graphene/polymer nanocomposites from graphite oxide
Vuluga, Daniela ULg; Thomassin, Jean-Michel ULg; Molenberg, Isabel et al

in Chemical Communications (2011), 47

The reduction of graphite oxide (GO) in the presence of reactive poly(methyl methacrylate) (PMMA), under mild biphasic conditions, directly affords graphene grafted with PMMA. The resulting nanocomposite ... [more ▼]

The reduction of graphite oxide (GO) in the presence of reactive poly(methyl methacrylate) (PMMA), under mild biphasic conditions, directly affords graphene grafted with PMMA. The resulting nanocomposite shows excellent electrical conductivities resulting from the optimal dispersion and exfoliation of graphene in the polymer matrix. [less ▲]

Detailed reference viewed: 78 (14 ULg)
Full Text
See detailHammett Acidity Scale in Ionic Liquids : An Indication of Their Weak Dissociating Character
Robert, Thierry ULg; Magna, Lionel; Olivier-Bourbigou, Hélène et al

Poster (2010, August)

Ionic liquids are salts with the particularity to exhibit melting points near room temperature (below 100°C, by convention) with no vapour tension. For this last reason, ionic liquids are sometimes called ... [more ▼]

Ionic liquids are salts with the particularity to exhibit melting points near room temperature (below 100°C, by convention) with no vapour tension. For this last reason, ionic liquids are sometimes called “green solvents”. In addition, their exclusive materials and solvent properties has led to an amazing increase of interest from both academic and industrial community, confirmed by the explosion of the number of published papers in the last decade. The many combinations of organic and inorganic cations and anions allow an infinity of new ionic solvents then permitting the selection of the desired properties for a given application. Nevertheless, it is impossible to investigate all these combinations and the unusual complexity of these new solvents gives rise to many controversies. Consequently, the development of the general rules for understanding the chemistry in ionic liquids is crucial. A fundamental property of solvent is its solvating power, for instance towards the proton. Therefore, we are interested to investigate the acid-base properties in ionic liquids in order to ultimately find a correlation with the acidic catalysis activity. We then have proposed a colorimetric method to determine the acidity levels accessible in these new media: the Hammett acidity function H0. This spectroscopic method is based on the protonation equilibrium for a family of coloured indicator with pKa’s assumed as solvent independent (following the Hammett proposition). This presentation will summarize our Hammett acidity measurements in several ionic liquids. - At first, we will show that it is possible to evaluate the Hammett acidity function with two different coloured indicators, in the same ionic liquid. Since the Hammett acidity of a given mixture was found to depend on the choosen coloured indicator, this suggests the formation of ions associations in ionic liquids. As a result, the ionic liquids are clearly not as dissociating as initially thought and the Hammett acidity function is in fact an apparent function, underestimating the real acidity level. - The apparent acidity functions have then been compared for several ionic liquids to which an acid has been added ([BMIm][NTf2], [BMIm][BF4], [BMIm][OTf], [BHIm][NTf2], [BMIm][PF6], [HNEt3][NTf2]). The conclusions are as follows: 1) the accessible acidity level is not influenced by the nature of the cation; 2) on the contrary, the nature of anion is very critical and the solvating power towards the proton follows the order: OTf- > NTf2- > BF4- > PF6-. The more the proton is solvated, the less it is acidic. - Finally, the difference of acidity of two acids, HOTf and HNTf2 (both strong acids in water), has been investigated in [BMIm][BF4], [BMIm][NTf2] and [BMIm][OTf]. In [BMIm][OTf], these two acids show the same acidity (they behave as strong acids) due to the solvent levelling effect; on the other hand, in [BMIm][NTf2] and [BMIm][BF4] allowing higher acidity levels, HNTf2 is stronger than HOTf . The observed difference is also another indication of the lower proton solvation in [BMIm][BF4] or [BMIm][NTf2] versus that in [BMIm][OTf]. [less ▲]

Detailed reference viewed: 367 (14 ULg)
See detailDevelopment of an analytical method to determine the cryolitic bath composition by Raman spectroscopy
Malherbe, Cédric ULg; Gilbert, Bernard ULg

Poster (2010, April 23)

Since the end of the nineteenth century, metallic aluminium is produced by electro-deposition from a solution of aluminium oxide in cryolitic melts around 1000°C (Hall-Héroult process). The industrial ... [more ▼]

Since the end of the nineteenth century, metallic aluminium is produced by electro-deposition from a solution of aluminium oxide in cryolitic melts around 1000°C (Hall-Héroult process). The industrial melt is composed mostly of cryolite (Na3AlF6) and AlF3 and is characterized by the molar NaF/AlF3 ratio, named cryolitic ratio (CR). It turns out that the bath composition is critical: for instance, it has been shown that a small change in the Al2O3 content leads to a great change in the overvoltage required for the electrolysis. Therefore controlling the melt composition is very important in order to reduce the energy lost. Unfortunately no in situ analytical method allows studying the composition of the melt yet. Considering our experience in the study of such highly corrosive media by Raman spectroscopy and since the bath spectrum is function of both the CR and the Al2O3 content, we have proposed in the past to apply that technique to the direct determination of the melt composition. Despite the CR could be well evaluated in the lab, experimental problems however made the practical application difficult. The purpose of this presentation will be to show the new results obtained on an updated instrument: - Spectra are recorded in 20 s or less with a higher quality than before. - The previously developed home-made software was adapted to the updated instrument and various spectra analysis procedures are under study. - A procedure to prepare reference samples was also developed taking into account the homogeneity problems that have been met. - The slopes of the alumina calibration curves are depending on the bath CR, in confirmation of our previous results. - The new results are compared with the previous ones. It will be concluded that Raman spectroscopy is indeed becoming a suitable technique for developing an analytical method to determine the composition of industrial cryolitic melts. [less ▲]

Detailed reference viewed: 42 (7 ULg)
Full Text
See detailQuantitative Evaluation of Imputities in Ionic Liquids
Robert, Thierry ULg; Olivier-Bourbigou, Hélène; Gilbert, Bernard ULg

Poster (2010, March)

Since several years, our laboratory is studying the acidity in ionic liquids and showed that very acidic levels can be reached in these media when a strong acid is added. These acidity levels were ... [more ▼]

Since several years, our laboratory is studying the acidity in ionic liquids and showed that very acidic levels can be reached in these media when a strong acid is added. These acidity levels were determined using Hammett acidity1 (spectroscopic method) and Strehlow acidity2 (potentiometric method) measurements. Considering the attainable acidity levels, it turns out that the purity of these ionic solvents is very critical because all impurities (i.e methylimidazole, water, acetone, chloride …) can act as (strong) bases. Therefore, it is imperative to quantify these impurities to obtain reproducible results. [less ▲]

Detailed reference viewed: 40 (6 ULg)
Full Text
See detailThe Hydrogen Electrode in Ionic Liquids: Acidity Measurements and Titrations
Robert, Thierry ULg; Malherbe, Cédric ULg; Magna, lionel et al

Poster (2010, March)

The acidity level in ILs containing acid was first determined using the Hammett acidity function (H0)1-2 in our laboratory. It was demonstrated that this attainable acidity, extending from -3 to -8, is ... [more ▼]

The acidity level in ILs containing acid was first determined using the Hammett acidity function (H0)1-2 in our laboratory. It was demonstrated that this attainable acidity, extending from -3 to -8, is exclusively depending of the nature of anion and follow the order: PF6 > BF4 > NTf2 > OTf. Nevertheless, the Hammett acidity function is an apparent function in this media and must then be corrected for. Consequently, in a second step, we tried to evaluate directly the proton activity from the determination of a potentiometric acidity function (R0) based on the extrathermodynamic Strehlow assumption.3 Therefore, the equilibrium potential of the H+/H2 couple was measured with an hydrogen electrode versus the ferricinium/ferrocene couple for which the potential is considered as independent of the solvent. [less ▲]

Detailed reference viewed: 126 (6 ULg)
Full Text
See detailAn analytical method to determine the composition of cryolitic melts involved in the Hall-Heroult process by Raman spectroscopy
Malherbe, Cédric ULg; Gilbert, Bernard ULg

Poster (2010, March)

The Hall-Héroult process involves the metallic aluminium production from electroreduction of aluminium oxide in cryolitic melt (mostly composed of cryolite and aluminium fluoride) around 1000°C. In order ... [more ▼]

The Hall-Héroult process involves the metallic aluminium production from electroreduction of aluminium oxide in cryolitic melt (mostly composed of cryolite and aluminium fluoride) around 1000°C. In order to reduce the energy loss during this process, controlling the melt composition turns out to be critical. Unfortunately, no in situ analytical method allows measuring the melt composition yet. Since the Raman spectrum of the melt depends on both the cryolitic ratio (molar NaF/AlF3 ratio, CR) and the aluminium oxide content, our laboratory proposed in the past to apply Raman spectroscopy for direct melt composition determination by recording the spectrum from the top. However, experimental problems made the practical application difficult. Nowadays, the method is becoming more feasible because of new instrumental developments such as new sensitive CCD, fiber optics and new optical filters. [less ▲]

Detailed reference viewed: 38 (0 ULg)
Full Text
Peer Reviewed
See detailGold-loaded carbon nanoparticles from poly(vinyl alcohol)-b-poly(acrylonitrile) non-shell-cross-linked micelles
Bryaskova, Rayna; Willet, Nicolas ULg; Duwez, Anne-Sophie ULg et al

in Chemistry : An Asian Journal (2009), 4(8), 1338-1345

Herein we show that a new amphiphilic poly(vinyl alcohol)-b-poly(acrylonitrile) block copolymer dispersed in water can be easily loaded with gold nanoparticles by addition of chlorauric acid followed by ... [more ▼]

Herein we show that a new amphiphilic poly(vinyl alcohol)-b-poly(acrylonitrile) block copolymer dispersed in water can be easily loaded with gold nanoparticles by addition of chlorauric acid followed by reduction by sodium borohydride. After deposition of the so-loaded micelles onto a silicon wafer, followed by an appropriate thermal treatment, the poly(acrylonitrile) core of the micelles is carbonized, while the poly(vinyl alcohol) shell is completely decomposed and volatilized, leading to gold encapsulated in carbon nanoparticles. The morphology of the micelles is maintained during thermal treatment without requiring shell-cross-linking of the micelles prior to pyrolysis. [less ▲]

Detailed reference viewed: 111 (36 ULg)
Full Text
Peer Reviewed
See detailAcidity in Ionic liquids: from the determination of an acidity scale to the application in catalytic reactions
Olivier-Bourbigou, Hélène; Gilbert, Bernard ULg; Magna, Lionel et al

Conference (2009)

Detailed reference viewed: 23 (1 ULg)
Full Text
Peer Reviewed
See detailTentative determination of the acidity level in room temperature ionic liquids by electrochemical methods
Malherbe, Cédric ULg; Robert, Thierry ULg; Magna, Lionel et al

in ECS Transactions (2009), 16(49), 3

In our attempt to evaluate the acidity levels reached by acidified ionic liquids (BMImBF4, BMImNTf2 and BMImOTf + HOTf or HNTf2), the uncertainty on the pKas of the indicators needed for the Hammett ... [more ▼]

In our attempt to evaluate the acidity levels reached by acidified ionic liquids (BMImBF4, BMImNTf2 and BMImOTf + HOTf or HNTf2), the uncertainty on the pKas of the indicators needed for the Hammett spectrophotometric procedure was pointed out. As consequence another method is proposed, based on the H+/H2 couple potential measurement. In this purpose, if dynamic methods failed mainly for lack of sufficient reversibility, potentiometry with a hydrogen electrode gave meaningful results. The R0(H+) Strehlow function, could be calculated, using the Fc+-Fc couple as reference assumed as solvent independent. The obtained results show that i) the acidities are much higher than those in water; ii) the acidities measured by the hydrogen electrode are higher than those measured by the Hammett method; iii) the sequence of acidities for solutions of similar content of added acid is still BF4 > NTf2 > OTf as previously measured with the Hammett method. [less ▲]

Detailed reference viewed: 43 (22 ULg)