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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; 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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See detailNew fluorinated surfactant for nanogels preparation in supercritical CO2
Alaimo, David ULg; Beigbeder, Alexandre; Dubois, Philippe et al

Poster (2011, April 29)

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See detailNew fluorinated surfactants for nanogels preparation in supercritical CO2
Alaimo, David ULg; Beigbeder, Alexandre; Dubois, Philippe et al

Poster (2010, November 29)

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See detailFoamability and structure analysis of foams in Hele-Shaw cell
Caps, Hervé ULg; Vandewalle, Nicolas ULg; Broze, Guy ULg et al

in Applied Physics Letters (2007), 90(21),

The authors have generated two-dimensional foams by imposing an intermittent drainage in a Hele-Shaw cell partially filled with a detergent/water mixture. The foam generation associated with this process ... [more ▼]

The authors have generated two-dimensional foams by imposing an intermittent drainage in a Hele-Shaw cell partially filled with a detergent/water mixture. The foam generation associated with this process is reproducible and depends on the surfactant molecules composing the solution. A kinetic model can be proposed for the foam evolution. The structure of the foam is also investigated: the average bubble side number and correlation functions are measured. Distinguishable behaviors are observed for different surfactant molecules. This way of producing a foam is thus adequate for applied foam structure characterizations and fundamental studies. (c) 2007 American Institute of Physics. [less ▲]

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See detailFoaming dynamics in Hele-Shaw cells
Caps, Hervé ULg; Vandewalle, Nicolas ULg; Broze, Guy ULg

in Physical Review E (2006), 73(6, Pt 2), 65301

We have studied foaming dynamics in Hele-Shaw cells partially filled with a soap and water mixture. A series of upside-down flips produces an intermittent wetting of the cell and leads to foam formation ... [more ▼]

We have studied foaming dynamics in Hele-Shaw cells partially filled with a soap and water mixture. A series of upside-down flips produces an intermittent wetting of the cell and leads to foam formation. As a function of the number of flips, an increasing number of bubbles composes the foam, until saturation is observed. Statistical analysis shows that the bubble size follows a Gamma distribution. Contrary to common belief, this foaming dynamics by "shaking" creates homogeneous foam, even though the system may pass through transient heterogeneous configurations. A mechanistic interpretation is proposed and included into a theoretical model. [less ▲]

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See detailInvestigation of the interactions of polyvinylpyrrolidone with mixtures of anionic and nonionic surfactants or anionic and zwitterionic surfactants by pulsed field gradient NMR
Misselyn-Bauduin, Anne-Marie; Thibaut, André ULg; Grandjean, Jean ULg et al

in Journal of Colloid & Interface Science (2001), 238(1), 1-7

The interaction of polyvinylpyrrolidone (PVP) with an anionic surfactant (sodium dodecyl sulfate, SDS), a nonionic surfactant (pentaethylene glycol monodecyl ether, C(10)E(5)), and a zwitterionic ... [more ▼]

The interaction of polyvinylpyrrolidone (PVP) with an anionic surfactant (sodium dodecyl sulfate, SDS), a nonionic surfactant (pentaethylene glycol monodecyl ether, C(10)E(5)), and a zwitterionic surfactant (lauryl amido propyl betaine, LAPB) has been investigated by means of pulsed gradient spin-echo NMR (FT-PGSE NMR), allowing self-diffusion coefficients to be determined. The results confirm the strong interaction prevailing in the PVP/SDS system, whereas no association has been observed in the PVP/C(10)E(5) and PVP/LAPB systems. Mixing PVP with two surfactants, namely SDS and C(10)E(5) or SDS and LAPB, results in the formation of ternary aggregates between the polymer and the mixed micelles. [less ▲]

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See detailAdsorption of Poly(vinylpyrrolidone)/Surfactant(s) mixtures at the silica/water interface: a calorimetric investigation
Thibaut, Anne; Misselyn-Bauduin, Anne-Marie; Broze, Guy ULg et al

in Langmuir (2000), 16(25), 9841-9849

The adsorption of binary mixtures of poly(vinylpyrrolidone) (PVP) and sodium dodecyl sulfate (SDS) and of ternary mixture of PVP, SDS, and pentaethylene glycol monodecyl ether (C10E5) onto silica has been ... [more ▼]

The adsorption of binary mixtures of poly(vinylpyrrolidone) (PVP) and sodium dodecyl sulfate (SDS) and of ternary mixture of PVP, SDS, and pentaethylene glycol monodecyl ether (C10E5) onto silica has been studied by the measurements of the adsorbed amount of PVP and the heat of adsorption. The amount of PVP adsorbed from the binary mixtures decreases as the SDS concentration is increased, whereas the enthalpy change passes through a maximum at SDS concentration of ca. 4 g/L. The chain conformation of PVP adsorbed on silica has been estimated from the adsorption data in relation to the surfactant concentration. It changes from loops and tails to trains upon increasing SDS concentration. At SDS concentrations higher than 4 g/L, a comblike conformation is observed. The adsorption of PVP/SDS/C10E5 ternary mixtures depends on the polymer concentration regime. [less ▲]

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See detailAdsorption of an aqueous mixture of surfactants on silica
Thibaut, Anne; Misselyn-Bauduin, Anne-Marie; Grandjean, Jean ULg et al

in Langmuir (2000), 16(24), 9192-9198

The behavior of mixtures of a nonionic surfactant, pentaethylene glycol monodecyl ether (C10E5), and an anionic surfactant, sodium dodecyl sulfate (SDS), was studied at the water−silica interface. In ... [more ▼]

The behavior of mixtures of a nonionic surfactant, pentaethylene glycol monodecyl ether (C10E5), and an anionic surfactant, sodium dodecyl sulfate (SDS), was studied at the water−silica interface. In contrast to the C10E5 surfactant, which is adsorbed at the silica−water interface at pH 6, the adsorption of the anionic surfactant is not observed. In the presence of SDS, the adsorption of C10E5 is severely restricted as result of the formation of mixed micelles in solution. This behavior is consistent with the adsorption free energy, ΔGads, of C10E5 and the free energy of mixed micellization, ΔGmix.mic, of SDS and C10E5. Flow microcalorimetry (FMC) results showed that the addition of C10E5/SDS mixtures to silica precoated with C10E5 resulted in the release of the preadsorbed nonionic surfactant; the whole phenomenon is exothermic. Combination of calorimetric data (FMC and isothermal titration calorimetry), self-diffusion coefficients, and the regular solution theory led to the conclusion that the main driving force for the C10E5 desorption was the formation of mixed micelles by unimeric SDS and the released nonionic surfactant. [less ▲]

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See detailMixed micelles of anionic-nonionic and anionic-zwitterionic surfactants analyzed by pulsed field gradient NMR
Misselyn-Bauduin, Anne-Marie; Thibaut, Anne; Grandjean, Jean ULg et al

in Langmuir (2000), 16(10), 4430-4435

The micellar composition of two binary surfactant systems, that is, sodium dodecyl sulfate (SDS)/pentaethylene glycol monodecyl ether (C10E5) and SDS/lauryl amido propyl betaine (LAPB), has been analyzed ... [more ▼]

The micellar composition of two binary surfactant systems, that is, sodium dodecyl sulfate (SDS)/pentaethylene glycol monodecyl ether (C10E5) and SDS/lauryl amido propyl betaine (LAPB), has been analyzed by pulsed gradient spin−echo NMR (FT-PGSE NMR). The experimental data have been compared to theoretical predictions based on the regular solution theory that takes into account the nonideal mixing of the surfactant pairs. Although good agreement between experiment and theory is observed for the SDS/C10E5 pair, some discrepancy is noted for the LAPB/SDS system, particularly at a high molar fraction of SDS. [less ▲]

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See detailHalato-telechelic polymers. VI. Viscoelastic properties of solutions of alkaline earth α, ω-dicarboxylatopolybutadiene
Broze, Guy ULg; Jérôme, Robert ULg; Teyssié, Philippe et al

in Macromolecules (1983), 16(6), 996-1000

Alkaline earth alpha,omega-dicarboxylatopolybutadienesd issolved in a nonpolar solvent (an= 4600) display an attractive thermorheological simplicity and exhibit a secondary relaxation characteristic of ... [more ▼]

Alkaline earth alpha,omega-dicarboxylatopolybutadienesd issolved in a nonpolar solvent (an= 4600) display an attractive thermorheological simplicity and exhibit a secondary relaxation characteristic of the ionic component. The shear-thickening character of these solutions is to be outlined. Their deformation mechanism is controlled by the stability and the mean size of the ionic multiplets formed by the carboxylate end groups. The electrostatic origin of the viscoelastic behavior observed is well established by its dependence on solvent, temperature, and cation size. [less ▲]

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See detailHalato-telechelic polymers. IV - Synthesis and dilute-solution behavior
Broze, Guy ULg; Jérôme, Robert ULg; Teyssié, Philippe

in Macromolecules (1982), 15(3), 920-927

Halato-telechelic polymers (HTP) result from the complete ionization of both ends of telechelic prepolymers. Their behavior in nonpolar solvents is characterized by a very abrupt increase of viscosity at ... [more ▼]

Halato-telechelic polymers (HTP) result from the complete ionization of both ends of telechelic prepolymers. Their behavior in nonpolar solvents is characterized by a very abrupt increase of viscosity at increasing concentration, so that gel formation is noted at concentrations as low as 1.5 gdL-'. The nature of the ion pairs, polarity of the medium, and temperature influence significantly the gel formation and prove its electrostatic origin. The depressive effect of any polar additive on the gelation requires drastic conditions in the synthesis of reproducible materials. In this respect, an efficient synthetic pathway has been proposed. The influence of molecular weight and end-to-end distance of the prepolymer shows the determinant role played by the polymeric backbone on the ion aggregation process. [less ▲]

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