References of "Debuigne, Antoine"
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See detailSynthèse enzymatique de surfactants sucrés dans le CO2 supercritique
Favrelle, Audrey ULg; Brognaux, Alison ULg; Debuigne, Antoine ULg et al

Poster (2009, October 15)

Les esters de carbohydrates sont des surfactants non ioniques ayant un vaste éventail d’applications commerciales en particulier dans l’industrie cosmétique, alimentaire et pharmaceutique. Ils sont ... [more ▼]

Les esters de carbohydrates sont des surfactants non ioniques ayant un vaste éventail d’applications commerciales en particulier dans l’industrie cosmétique, alimentaire et pharmaceutique. Ils sont produits à partir de matières premières renouvelables et peu coûteuses, et sont biodégradables et non toxiques. De manière générale, la synthèse d’esters de sucre nécessite de nombreuses étapes de protection/déprotection des groupements hydroxyles, le nombre et la position exacte des substituants greffés sur un squelette osidique étant des paramètres difficiles à contrôler lors des réactions chimiques. En revanche, la spécificité de certaines enzymes, et en particulier des lipases, peut être mise à profit pour modifier les sucres en milieux organiques. L’utilisation des lipases permet ainsi un meilleure sélectivité et énantiosélectivité des réactions d’estérification et de transestérification. D’autre part, la voie enzymatique permet d’effectuer ces réactions dans des conditions expérimentales beaucoup plus douces de température, de pH et de pression, par rapport aux synthèses réalisées à l’aide de catalyseurs chimiques. Le dioxyde de carbone supercritique (Sc-CO2), quant à lui, constitue une alternative intéressante aux solvants organiques couramment utilisés dans ce domaine car il est non toxique, chimiquement inerte, non inflammable…. Par exemple, son utilisation réduit la contamination des produits finaux avec des solvants résiduels. Ces avantages lui confèrent un large potentiel d’applications notamment dans l’industrie alimentaire, cosmétique, pharmaceutique mais également des matériaux. Notre travail consiste donc à développer la synthèse enzymatique de surfactants sucrés en milieu Sc-CO2 et d’étudier l’influence de divers paramètres sur la réaction biocatalysée. L’activité enzymatique et les rendements observés lors de nos expériences préliminaires dans le Sc-CO2 seront présentés ici et comparés avec ceux obtenus dans des solvants organiques traditionnels. [less ▲]

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See detailOptimisation de l'acylation enzymatique du mannose par l'utilisation de co-solvants
Brognaux, Alison ULg; Favrelle, Audrey ULg; Deleu, Magali ULg et al

Poster (2009, October 15)

Les esters de sucres sont des surfactants non-ioniques avec de nombreuses applications dans l’industrie alimentaire et pharmaceutique. La synthèse enzymatique est généralement préférée à la synthèse ... [more ▼]

Les esters de sucres sont des surfactants non-ioniques avec de nombreuses applications dans l’industrie alimentaire et pharmaceutique. La synthèse enzymatique est généralement préférée à la synthèse chimique. En effet, cette dernière consomme beaucoup d’énergie, est moins sélective envers les différents groupes hydroxyle du sucre et conduit à des produits de caramélisation. Le type de solvant, le ratio sucre / lipide, la température et le type de lipase immobilisée peuvent être modifiés afin d’optimiser la vitesse initiale et le rendement de réaction. Les travaux décrits rapportent l’optimisation de la synthèse enzymatique de myristate de mannosyle à partir de mannose et d’acide myristique en présence de la lipase de Candida antarctica B (Novozyme 435). Les concentrations optimales en mannose et en acide myristique sont respectivement de 0,1 et 0,6 M dans du tert-butanol pur à 60°C. Ces conditions conduisent à une vitesse initiale de 1,3 g/l.h pour 2 g/l d’enzyme et à un rendement molaire de 55%. Afin d’améliorer cette vitesse initiale de réaction, différents mélanges de tert-butanol et de co-solvants polaires ont été testés. Les solvants polaires (log P faibles) augmentent la solubilité des sucres mais provoquent l’inactivation partielle des lipases. Lorsque le log P est supérieur à 3, l’enzyme reste active mais ce type de milieu n’est pas approprié si les deux substrats diffèrent grandement en terme de polarité. Le but de cette étude est donc de trouver un compromis entre la solubilité du sucre et le maintient de l’activité enzymatique. Les quatre co-solvants testés sont le DMSO, le DMF, le formamide et la pyridine. Au terme de ce travail, le DMSO, à raison de 10 % dans le milieu réactionnel, s’est avéré être le meilleur co-solvant parmi ceux testés. Dans ces conditions, la vitesse initiale de réaction est accrue de 130 %. [less ▲]

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See detailElectrostatic hierarchical assembly in aqueous solutions of two oppositevely charged double hydrophilic diblock copolymers
Voets, Ilja K.; de Keizer, Arie; Leermakers, Frans A. M. et al

in European Polymer Journal (2009), 45(10), 2913-2925

The formation of spherical micelles in aqueous solutions of poly(N-methyl-2-vinyl pyridinium iodide)-block-poly(ethylene oxide), P2MVP-b-PEO and poly(acrylic acid)-block-poly(vinyl alcohol), PAA-b-PVOH ... [more ▼]

The formation of spherical micelles in aqueous solutions of poly(N-methyl-2-vinyl pyridinium iodide)-block-poly(ethylene oxide), P2MVP-b-PEO and poly(acrylic acid)-block-poly(vinyl alcohol), PAA-b-PVOH has been investigated with light scattering-titrations, dynamic and static light scattering, and 1H 2D Nuclear Overhauser Effect Spectroscopy. Complex coacervate core micelles, also called PIC micelles, block ionomer complexes, and interpolyelectrolyte complexes, are formed in thermodynamic equilibrium under charge neutral conditions (pH 8, 1 mM NaNO3, T = 25 °C) through electrostatic interaction between the core-forming P2MVP and PAA blocks. 2D 1H NOESY NMR experiments show no cross-correlations between PEO and PVOH blocks, indicating their segregation in the micellar corona. Self-consistent field calculations support the conclusion that these C3Ms are likely to resemble a ‘patched micelle’; that is, micelles featuring a ‘spheres-on-sphere’ morphology. [less ▲]

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See detailCobalt mediated radical polymerization (CMRP) using bis(acetylacetonato)cobalt(II): a unique tool for controlling the radical polymerization of conjugated and unconjugated vinyl monomers
Hurtgen, Marie ULg; Debuigne, Antoine ULg; Jérôme, Christine ULg et al

Poster (2009, September 17)

Cobalt-Mediated Radical Polymerization (CMRP) imparts a high level of control on the polymerization of acrylic and vinylic esters, acrylic acid and acrylonitrile. However, each class of monomers appears ... [more ▼]

Cobalt-Mediated Radical Polymerization (CMRP) imparts a high level of control on the polymerization of acrylic and vinylic esters, acrylic acid and acrylonitrile. However, each class of monomers appears to be controlled by one class of cobalt complexes. For example, the polymerization of acrylates and acrylic acid is mediated by cobalt porphyrin complexes while vinyl acetate (VAc) and acrylonitrile are efficiently controlled by bis(acetylacetonato)cobalt(II) (Co(acac)2). Therefore, a challenging issue in CMRP remains to broaden the range of monomers that can be controlled by the same cobalt complex. Recently, the controlled random copolymerization of butyl acrylate (BuA) with VAc was performed using the conventional V-70/Co(acac)2 CMRP system, but the homopolymerization of BuA remained uncontrolled. In this work, we used a new alkylcobalt(III) adduct to initiate and control the copolymerization of BuA with VAc. This achievement resulted in a significant improvement over the V-70/Co(acac)2 pair regarding the molecular weight control and the polydispersity indexes. Moreover, for the first time, the alkylcobalt(III) adduct was also efficient in controlling the homopolymerization of BuA and yielded low polydispersity PBuA even in the absence of VAc. These results indicate that Co(acac)2 is a versatile mediator for the CMRP of both unconjugated vinyl monomers (VAc, N-vinylpyrrolidone) and conjugated monomers such as acrylates. It gives access to copolymers that cannot be prepared by other controlled radical polymerization techniques. [less ▲]

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See detailCobalt-mediated radical polymerization of vinyl monomers: investigation of cobalt-coordination
Debuigne, Antoine ULg; Piette, Yasmine ULg; Poli, Rinaldo et al

Poster (2009, September 17)

Controlled Radical Polymerization techniques have been developed to obtain well-defined architectures and to control polymer parameters. Among these systems is Cobalt-Mediated Radical Polymerization (CMRP ... [more ▼]

Controlled Radical Polymerization techniques have been developed to obtain well-defined architectures and to control polymer parameters. Among these systems is Cobalt-Mediated Radical Polymerization (CMRP), which is based on the reversible deactivation of the growing radical chains with a cobalt complex, the cobalt (II) bis(acetylacetonate). The interest of this system is not only due to its ability to control the polymerization of very reactive monomers such as vinyl acetate (VAc) and N-vinylpyrrolidone (NVP), but also its peculiar mechanism which exhibits two pathways depending on the polymerization conditions; a reversible termination process and a degenerative chain transfer mechanism. Furthermore, it has been showed that the Co-C bond strength and thus the polymerization are strongly influenced by the use of some additives, such as water, dimethylformamide, dimethylsulfoxide and pyridine, which coordinate the cobalt free site. In this presentation we report the use of a preformed alkyl-cobalt(III) adduct as initiator for the polymerization of various vinyl monomers of different reactivity (VAc, acrylonitrile,…) and on the effect of several ligands on their polymerization control. The preparation of novel block copolymers by CMRP will finally be presented. As a conclusion, cobalt-coordination appears today as a unique opportunity to adjust the Co-C bond strength and to push back the bounds of possibilities in terms of macromolecular engineering assisted by CMRP. [less ▲]

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See detailSynthesis of novel block copolymers by cobalt-mediated radical polymerization (CMRP) and isoprene-assisted radical coupling reaction (I-ARC)
Debuigne, Antoine ULg; Jérôme, Christine ULg; Detrembleur, Christophe ULg

Conference (2009, September 17)

Nowadays, progresses in medicine, biotechnology, microelectronic and many other fields are more and more sustained by the development of novel polymer materials with constantly improved properties and ... [more ▼]

Nowadays, progresses in medicine, biotechnology, microelectronic and many other fields are more and more sustained by the development of novel polymer materials with constantly improved properties and well-defined molecular parameters. In this context, we designed an innovative and very promising tool for macromolecular engineering. This technique, called Isoprene-Assisted Radical Coupling (I-ARC), allows to couple quantitatively polymer chains preformed by Cobalt-Mediated Radical Polymerization (CMRP), an efficient controlled radical polymerization system for vinyl acetate (VAc) and acrylonitrile (AN). Typically, addition of isoprene to well-defined polymers prepared by CMRP invariably leads to the quantitative coupling reaction of the chains, as assessed by the perfect doubling of the molar mass of the polymer. Importantly, the I-ARC reaction is not limited to macromolecules with low molar masses and homopolymers, contrary to the previously reported radical chains coupling methods. Indeed, when applied to diblock copolymers, I-ARC constitutes a straightforward approach for the synthesis of telechelic symmetrical ABA triblock copolymers, as illustrated by the preparation of poly(vinyl acetate)-b-poly(acrylonitrile)-b-poly(vinyl acetate) triblock copolymers and their derivatives. [less ▲]

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See detailKey role of metal-coordination in cobalt-mediated radical polymerization of vinyl acetate
Debuigne, Antoine ULg; Poli, Rinaldo; Jérôme, Robert ULg et al

in Matyjaszewski, Krzysztof (Ed.) Controlled/living radical polymerization: progress in RAFT, DT, NMP & OMRP (2009)

Cobalt mediated radical polymerization (CMRP) of vinyl acetate (VAc) follows a reversible termination mechanism when initiated from a preformed alkyl-cobalt(III) complex. In these particular conditions ... [more ▼]

Cobalt mediated radical polymerization (CMRP) of vinyl acetate (VAc) follows a reversible termination mechanism when initiated from a preformed alkyl-cobalt(III) complex. In these particular conditions, CMRP functions as a stable free radical process and fine tuning of the Co-C bond strength becomes crucial. Increase of temperature and addition of molecules, such as water, dimethylformamide and dimethylsulfoxide, able to coordinate the cobalt complex appeared as efficient strategies to weaken the Co-C bond and thus to speed up the polymerization while maintaining a very good control of the VAc polymerization. The key role of metal-coordination was investigated by kinetic measurements combined with DFT calculations. [less ▲]

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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 ▲]

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See detailUnusual quantitative (co)polymer chain coupling reaction based on isoprene and cobalt complexes
Debuigne, Antoine ULg; Jérôme, Christine ULg; Detrembleur, Christophe ULg

Conference (2009, July 15)

Nowadays, progresses in medicine, biotechnology, microelectronic and many other fields are more and more sustained by the development of novel polymer materials with constantly improved properties and ... [more ▼]

Nowadays, progresses in medicine, biotechnology, microelectronic and many other fields are more and more sustained by the development of novel polymer materials with constantly improved properties and well-defined molecular parameters. In this context, we designed an innovative and very promising tool for macromolecular engineering. This technique, called Isoprene-Assisted Radical Coupling (I-ARC), allows to couple quantitatively polymer chains preformed by Cobalt-Mediated Radical Polymerization (CMRP), an efficient controlled radical polymerization system for vinyl acetate (VAc) and acrylonitrile (AN). Typically, addition of isoprene to well-defined polymers prepared by CMRP invariably leads to the quantitative coupling reaction of the chains, as assessed by the perfect doubling of the molar mass of the polymer. Importantly, the I-ARC reaction is not limited to macromolecules with low molar masses and homopolymers, contrary to the previously reported radical chains coupling methods. Indeed, when applied to diblock copolymers, I-ARC constitutes a straightforward approach for the synthesis of telechelic symmetrical ABA triblock copolymers, as illustrated by the preparation of poly(vinyl acetate)-b-poly(acrylonitrile)-bpoly(vinyl acetate) triblock copolymers and their derivatives. [less ▲]

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See detailEnzymatic modifications of sugar in supercritical carbon dioxide
Favrelle, Audrey ULg; Brognaux, Alison ULg; Debuigne, Antoine ULg et al

Poster (2009, July 07)

Carbohydrates esters are non-ionic surfactants that have a wide range of commercial applications in cosmetic, food and pharmaceutical industry. They are produced from renewable and inexpensive raw ... [more ▼]

Carbohydrates esters are non-ionic surfactants that have a wide range of commercial applications in cosmetic, food and pharmaceutical industry. They are produced from renewable and inexpensive raw materials, are bio-degradable and non-toxic. Chemical synthesis of sugar esters is generally performed at a high temperature in the presence of an alkaline catalyst lead-ing to a mixture of products. In this respect, the corresponding enzyme-catalyzed processes in non-conventional media are more selective. For this purpose, lipases are the most useful enzymes. Moreover, supercritical carbon dioxide (SC-CO2) constitutes an interesting alternative to the organic solvents used in the domain as it is considered to be environmentally frien-dlier and safer. For example, its use reduces the contamination of the final products with residual solvents. This property is particularly valued in food, cosmetic and pharmaceutical industry. Our work consists to carry out lipase catalyzed sugar modifications in SC-CO2 and to compare the results with those obtained in organic solvents. The effect of these two different media on the enzyme stability and the yield will be described here. Moreover, the impact of various factors such as pressure, temperature, enzyme form (free or immobilized), use of co-solvent, on the course of the sugar esterification will be discussed. [less ▲]

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See detailNovel (co)polymers by cobalt-mediated radical polymerization
Debuigne, Antoine ULg; Piette, Yasmine ULg; Poli, Rinaldo et al

Poster (2009, April 24)

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See detailThe influence of cobalt-coordination on cobalt-mediated radical polymerization of vinyl monomers
Debuigne, Antoine ULg; Piette, Yasmine ULg; Poli, Rinaldo et al

Poster (2009, March 19)

Nowadays, polymers are a part of everyday life. Researchers encouraged by growing need in high performance polymers develop new synthesis tools to manage the molecular architecture and thus the polymer ... [more ▼]

Nowadays, polymers are a part of everyday life. Researchers encouraged by growing need in high performance polymers develop new synthesis tools to manage the molecular architecture and thus the polymer properties. In this context, CRP (Controlled Radical Polymerization) techniques have been developed to obtain well-defined architectures and to control polymer parameters. Among these systems is Cobalt-Mediated Radical Polymerization (CMRP), which is based on the reversible deactivation of the growing radical chains with a cobalt complex, the cobalt (II) bis-acetylacetonate. The interest of this system is not only due to its ability to control the polymerization of very reactive monomers such as vinyl acetate (VAc) and N-vinylpyrrolidone (NVP), but also its peculiar mechanism which exhibits two pathways depending on the polymerization conditions; a reversible termination process and a degenerative chain transfer mechanism. Furthermore, it has been showed that the Co-C strength and thus the polymerization are strongly influenced by the use of some additives, such as water, dimethylformamide, dimethylsulfoxide and pyridine, which coordinate the cobalt free site. In this presentation we report the use of a preformed alkyl-cobalt(III) adduct as initiator for the polymerization of acrylonitrile (AN) and the use of these ligands in the CMRP system to synthesize well-defined poly(vinyl acetate)-b-poly(acrylonitrile) block copolymers. As a conclusion, cobalt-coordination appears today as a unique opportunity to adjust the Co-C bond strength and to push back the bounds of possibilities in terms of macromolecular engineering assisted by CMRP. [less ▲]

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See detailHow can cobalt complexes help synthetic polymer chemists?
Debuigne, Antoine ULg; Jérôme, Robert ULg; Jérôme, Christine ULg et al

Conference (2009, March 19)

Nowadays, progresses in medicine, biotechnology, microelectronic and many other fields are more and more sustained by the development of novel polymer materials with constantly improved properties and ... [more ▼]

Nowadays, progresses in medicine, biotechnology, microelectronic and many other fields are more and more sustained by the development of novel polymer materials with constantly improved properties and well-defined molecular parameters. In this context, we designed a controlled radical polymerization (CRP) technique based on cobalt complexes which is able to efficiently control the radical polymerization of challenging monomers such as vinyl acetate (VAc), N-vinyl pyrrolidone (NVP) and acrylonitrile (AN). This so-called Cobalt-Mediated Radical Polymerization (CMRP) also gave access to unique diblock copolymers by sequential polymerization of the above mentioned monomers. However, addition of isoprene to polymer chains preformed by CMRP did not lead to the expected poly(isoprene) containing copolymers. Instead, the quantitative coupling reaction of the polymer chains was observed, as assessed by the perfect doubling of the molar mass of the initial macromolecules. This result is very exciting because this so-called Isoprene-Assisted Radical Coupling (I-ARC) reaction is not limited to polymers with low molar masses and homopolymers, contrary to the existing radical chains coupling methods. Indeed, when applied to diblock copolymers, IARC constitutes a straightforward approach for the synthesis of telechelic symmetrical ABA triblock copolymers and is thus a very promising tool for macromolecular engineering. [less ▲]

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See detailOverview of cobalt-mediated radical polymerization: roots, state of the art and future prospects
Debuigne, Antoine ULg; Poli, Rinaldo; Jérôme, Christine ULg et al

in Progress in Polymer Science (2009), 34(3), 211-239

Controlled radical polymerization (CRP) techniques offer the opportunity to properly design polymer chains and adjust their chemical and physical properties. Among these techniques, cobalt-mediated ... [more ▼]

Controlled radical polymerization (CRP) techniques offer the opportunity to properly design polymer chains and adjust their chemical and physical properties. Among these techniques, cobalt-mediated radical polymerization (CMRP) distinguished itself by the high level of control imparted to the polymerization of acrylic and vinyl ester monomers, even for high molar masses. This article summarizes for the first time the advances in understanding and synthetic scope of CMRP since its discovery. Notably, the cobalt–carbon bond formation by dual contribution of reversible termination and degenerative chain transfer is discussed, as well as the impact of additives able to coordinate the metal. The potential of computational chemistry in the field of CMRP as a rationalization and predicting tool is also presented. These mechanistic considerations and achievements in macromolecular engineering will be discussed along with challenges and future prospects in order to assess the CMRP system as a whole. [less ▲]

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See detailIsoprene-assisted radical coupling of (co)polymers prepared by cobalt-mediated radical polymerization
Debuigne, Antoine ULg; Jérôme, Christine ULg; Detrembleur, Christophe ULg

in Angewandte Chemie (International ed. in English) (2009), 48(8), 1422-1424

The isoprene-assisted radical coupling (I-ARC) of polymers prepared by cobalt-mediated radical polymerization (see picture) is the first efficient radical coupling method that is not restricted to short ... [more ▼]

The isoprene-assisted radical coupling (I-ARC) of polymers prepared by cobalt-mediated radical polymerization (see picture) is the first efficient radical coupling method that is not restricted to short chains. When applied to AB diblock copolymers, I-ARC constitutes a straightforward approach to the preparation of novel symmetrical ABA triblock copolymers [less ▲]

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See detailCobalt-assisted synthesis of novel block copolymers
Debuigne, Antoine ULg

Scientific conference (2009, February 05)

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