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See detailDesign of macroporous poly(ionic liquid)s by CO2/water emulsion templated polymerization
Boyère, Cédric ULg; Favrelle, Audrey; Boury, Frank et al

Poster (2013, November 20)

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See detailMonocatenary, branched, double-headed and bolaform surface active carbohydrate esters via photochemical thiol-ene/-yne reactions
Boyère, Cédric ULg; Broze, Guy ULg; Blecker, Christophe ULg et al

in Carbohydrate Research (2013), 380

An original and versatile method for the synthesis of a range of novel mannose-based surfactants was developed via metal-free photo-induced thiol-ene/-yne “click” reactions. This light-mediated ... [more ▼]

An original and versatile method for the synthesis of a range of novel mannose-based surfactants was developed via metal-free photo-induced thiol-ene/-yne “click” reactions. This light-mediated hydrothiolation reaction involving a thiolated mannose was successfully applied to terminal and internal alkenes, dienes and alkynes, leading to monocatenary, branched, double-headed and bolaform amphiphilic carbohydrate esters,respectively. A surface activity study showed that these new compounds possess valuable properties and display specific behavior at the air-water interface. It also demonstrated the greater flexibility of the thioether moiety in the spacer of the surfactants produced via a thiol-ene reaction in comparison withthe triazole heterocyclic rings in similar glucose-based surfactants synthesized elsewhere by the alkyne-azide 1,3-dipolar addition. [less ▲]

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See detailDesign of sugar-based surface active agents for emulsion polymerization in supercritical carbon dioxide
Boyère, Cédric ULg

Doctoral thesis (2013)

The use of supercritical CO2 (scCO2) as alternative to traditional organic solvents and the valorization of biomass are interesting approaches to reduce the ecological footprint of chemical processes. On ... [more ▼]

The use of supercritical CO2 (scCO2) as alternative to traditional organic solvents and the valorization of biomass are interesting approaches to reduce the ecological footprint of chemical processes. On the other hand, emulsions offers many advantages over bulk and solution processes for polymerization reactions including limited environmental impact, ease of products recovery and increased reaction rate. In this context, this thesis aims to design novel fluorinated sugar-based surfactants able to stabilize water/CO2 (W/C) emulsion systems and explore their potential as template for polymerization reactions. Such surface active agents were prepared either by lipase-catalyzed esterification of mannose with fluorinated acid derivatives or following chemoenzymatic approaches involving very efficient and versatile "click" chemistries like the thiol-Michael addition or the thiol-ene/-yne reactions. The W/C interfacial activity of these novel glycosurfactants was confirmed by tensiometry as well as their ability to form stable W/C microemulsions. Then, we tested a range of these neutral fluorinated carbohydrate esters as stabilizers for the CO2-in-water (C/W) emulsion polymerization. In particular, the radical polymerization of acrylamide was performed in the continuous aqueous phase of a C/W high internal phase emulsion (HIPE) leading to highly interconnected macroporous polymer matrices, also called polyHIPEs. In this case, we emphasized a clear dependence of morphology of the porous structure with the concentration and the structure of the glycosurfactant. Thanks to the electrical neutrality of these fluorinated glycosurfactants which confers them a lower sensitivity to the ionic forces compared to their ionic counterparts, we could extend this system to the polymerization of ionic liquid monomers. Porous poly(ionic liquid)s were thus formed by emulsion polymerization for the first time and exhibit spherical cells interconnected by pores with size (~ 1 μm) among the lowest reported for polyHIPEs produced from C/W emulsions. The emulsion C/W templating methodology based on the designed fluorinated glycosurfactants thus appears as a technique of choice for the preparation of valuable macroporous polymer matrices. [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 detailMacroporous polyhipes from CO2-in-water emulsion templates stabilized by new sugar-based surfactants
Boyère, Cédric ULg; Favrelle, Audrey; Léonard, Alexandre F. et al

Poster (2013, May 16)

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See detailSurface activity of a fluorinated carbohydrate ester in water/carbon dioxide emulsions
Favrelle, Audrey; Boyère, Cédric ULg; Tran, Kien My et al

in Journal of Colloid & Interface Science (2013), 398

The water/carbon dioxide (W/CO2) interfacial activity and emulsifying capacity of hydrocarbon and fluorinated carbohydrate esters are investigated of the first time and compared to the performance of ... [more ▼]

The water/carbon dioxide (W/CO2) interfacial activity and emulsifying capacity of hydrocarbon and fluorinated carbohydrate esters are investigated of the first time and compared to the performance of sodium-bis(2-ethylhexyl)sulfosuccinate (AOT). The reduction of the W/CO2 interfacial tension was measured using a pendant drop tensiometer equipped with a cell view pressurized with CO2 at 80 bar and 45 °C. It was found that the interface stabilization improved in the order AOT < 6-O-myristoyl mannose < 6-O-(2H,2H,3H,3H-perfluoroundecanoyl)-D-mannose. In the latter case, a drastic reduction of the W/CO2 interfacial tension was observed (85% reduction, interfacial tension at the equilibrium = 3.6 mN/m), which emphasizes the advantage of using a fluorinated CO2-philic tail and the potential of sugars as hydrophilic head. The formulation of stable W/CO2 emulsions was also achieved using the fluorinated mannose derivative. This study paves the way to the design of a novel class of competitive surface active agents for W/CO2 emulsions. [less ▲]

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See detailUse of new surface active carbohydrate esters for the synthesis of polyhipes in supercritical CO2
Boyère, Cédric ULg; Favrelle, Audrey; Grignard, Bruno ULg et al

Poster (2012, September 10)

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See detailSynthesis of microsphere-loaded porous polymers by combining emulsion and dispersion polymerisations in supercritical carbon dioxide
Boyère, Cédric ULg; Léonard, Alexandre ULg; Grignard, Bruno ULg et al

in Chemical Communications (2012), 48(67), 8356-8358

Highly porous materials were produced by acrylamide polymerisation templated by supercritical CO2-in-water emulsions using new fluorinated glycosurfactants. Properties of the resulting polymer scaffolds ... [more ▼]

Highly porous materials were produced by acrylamide polymerisation templated by supercritical CO2-in-water emulsions using new fluorinated glycosurfactants. Properties of the resulting polymer scaffolds were tuned by performing dispersion polymerisations within their cavities filled with supercritical CO2. [less ▲]

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See detailUse of glycosurfactants for the synthesis of polyHIPES in supercritical carbon dioxide
Boyère, Cédric ULg; Favrelle, Audrey; Léonard, Alexandre ULg et al

Poster (2012, June 04)

The abstract is available as a pdf file.

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See detailDesign of sugar-based surface active agents for emulsion polymerization in supercritical carbon dioxide
Boyère, Cédric ULg; Favrelle, Audrey; Broze, Guy ULg et al

Conference (2012, May 10)

The use of aqueous dispersed media, such as emulsions, has many advantages over solution processes for chemical transformations and polymerization reactions, i.e. limited environmental impact, ease of ... [more ▼]

The use of aqueous dispersed media, such as emulsions, has many advantages over solution processes for chemical transformations and polymerization reactions, i.e. limited environmental impact, ease of products recovery and increased reaction rate. Emulsions are usually implemented from a water/organic solvent mixture in the presence of a surfactant. However, supercritical carbon dioxide (scCO2) (Pc =74 bars; Tc = 31°C) constitutes an interesting alternative to the traditional organic solvents in these heterogeneous systems because it is inexpensive, non-toxic, non-inflammable and environmentally friendlier. In this context, we developed a novel class of surfactants for the stabilization of H2O/scCO2 emulsions, i.e. fluorinated modified carbohydrates. The hydrophilic head of the surfactant consists in a sugar moiety whereas a fluorinated tail is specifically located in the scCO2 phase. The strategies for the synthesis of these carbohydrates esters rely on selective lipase-catalyzed modifications of sugars and on the versatile thiol-Michael addition reaction. The ability of these molecules to decrease the H2O/scCO2 interfacial tension and to stabilize such emulsions will be presented. Finally, high internal phase scCO2-in-water emulsion (HIPE) were prepared with these new surfactants and used as template for the acrylamide polymerization. The monomer is polymerized in the continuous aqueous phase before removing the CO2 droplets (at least 70 % of the total volume). The resulting permeable porous polymers, called polyHIPEs, exhibit highly interconnected voids (cfr SEM picture) and should be valuable in many applications including support for catalyst, filtration process, immobilization of proteins, etc. [less ▲]

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See detailCombination of lipase catalysis and thiol-Michael addition for the synthesis of carbohydrate esters used as stabilizers in supercritical carbon dioxide emulsions
Boyère, Cédric ULg; Favrelle, Audrey; Broze, Guy ULg et al

Poster (2011, November 21)

The use of aqueous dispersed media, such as emulsions and miniemulsions, has many advantages over solution processes for chemical transformations and polymerization reactions, i.e. limited environmental ... [more ▼]

The use of aqueous dispersed media, such as emulsions and miniemulsions, has many advantages over solution processes for chemical transformations and polymerization reactions, i.e. limited environmental impact, ease of products recovery and increased reaction rate. Although, dispersed media are usually implemented from water/solvent mixtures, supercritical carbon dioxide (scCO2) (Pc =74 bars; Tc = 31°C) constitutes an interesting alternative to the traditional organic solvents because it is inexpensive, non-toxic, non-flammable and environmentally friendlier. In this context, we develop a novel class of surface active compounds able to stabilize water/scCO2 emulsions, i.e. fluorinated modified carbohydrates. The hydrophilic head of the surfactant consists in a sugar moiety whereas the fluorinated tail has a strong affinity for the scCO2 phase. These carbohydrate esters are prepared by a two-step strategy which takes advantage of the selectivity of enzymatic catalysis and the versatility of the thiol-Michael addition reaction. The new thiolated mannose intermediate is a useful building block for the incorporation of unprotected sugar moieties into complex molecules. The surface active properties of the fluorinated derivatives have been evaluated as well as their use as stabilizers for the preparation of microparticles and highly porous polymer materials in scCO2. [less ▲]

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See detailLipase catalysis and thiol-Michael addition: a relevant association for the synthesis of new surface active carbohydrate esters
Boyère, Cédric ULg; Favrelle, Audrey ULg; Broze, Guy ULg et al

in Carbohydrate Research (2011), 346(14), 2121-2125

A novel class of surface-active carbohydrate esters is prepared by a two-step strategy that takes advantage of the selectivity of enzymatic catalysis and the versatility of the thiol-Michael addition ... [more ▼]

A novel class of surface-active carbohydrate esters is prepared by a two-step strategy that takes advantage of the selectivity of enzymatic catalysis and the versatility of the thiol-Michael addition reaction. The surfactant performance of the produced aliphatic, fluorinated and silicon based sugar esters are evaluated by surface tension measurements. The novel thiolated mannose, made available in this work, appears as a powerful building block for the incorporation of unprotected sugar moieties into complex molecules. [less ▲]

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See detailEnzymatic synthesis and surface active properties of novel hemifluorinated mannose esters
Favrelle, Audrey ULg; Boyère, Cédric ULg; Laurent, Pascal ULg et al

in Carbohydrate Research (2011), 346(9), 1161-1164

The lipase-catalysed esterification of sugars with hemifluorinated acid derivatives is reported for the first time. A series of mannose modified derivatives having fluorinated chains with different length ... [more ▼]

The lipase-catalysed esterification of sugars with hemifluorinated acid derivatives is reported for the first time. A series of mannose modified derivatives having fluorinated chains with different length have been prepared accordingly in moderate yield. A preliminary evaluation of the surface active properties of these hemifluorinated mannose esters revealed their ability to reduce the surface tension of water much more efficiently than their aliphatic counterparts. [less ▲]

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