References of "Grandjean, Jean"
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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 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 detailStudy of the propagation center in the anionic polymerization of (meth)acrylic monomers: NMR study of Di-tert-butyl 2-Lithio-2.4'-trimethylglutarate and living poly(tert-butyl methacrylate) oligomers in THF/toluene mixtures
Zune, Catherine; Dubois, Philippe ULg; Grandjean, Jean ULg et al

in Macromolecules (1999), 32(7), 5477-5486

Solvation influences both the stereoregularity and molecular weight distribution (MWD) of poly(tert-butyl methacrylate) (PtBMA) prepared by anionic polymerization of tBMA with a lithium counterion in THF ... [more ▼]

Solvation influences both the stereoregularity and molecular weight distribution (MWD) of poly(tert-butyl methacrylate) (PtBMA) prepared by anionic polymerization of tBMA with a lithium counterion in THF/toluene mixed solvents at −78 °C. As a probe of the structural changes of the propagating species, multinuclear 7Li, 1H, and 13C NMR analysis of di-tert-butyl 2-lithio-2,4,4‘-trimethylglutarate (a model dimer, A) and of short-length living PtBMA chains is reported and discussed. Whatever the system, the main structure of the lithium ester enolate in THF/toluene mixtures is similar to that one reported in THF. In the case of A and for toluene contents exceeding 50% v/v, partly organized pseudophases can additionally be detected in the 7Li NMR spectra, but they do not provide well-developed 1H and 13C NMR signals. The chemical shifts of 1H and 13C signals of A support the dimeric form of this model. An equilibrium between dimeric and nonaggregated living PtBMA chains has been previously proposed to dominate in pure THF. However, marked self-termination of low-molecular weight living oligomers prepared in THF/toluene mixtures can be observed at 263 K, in contrast to the stability observed in pure THF up to 298 K. Another contrasting feature is the broadening of the molecular weight distribution which can be explained by an aggregation process that stabilizes oligomers at the early stage of the anionic polymerization as supported by SEC-RI and SEC-UV eluograms. [less ▲]

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See detailAnalysis of living tert-butyl methacrylate oligoanions in tetrahydrofuran by NMR spectroscopy, viscosity and light scattering
Zune, Catherine; Dubois, Philippe; Grandjean, Jean ULg et al

in Macromolecular Chemistry and Physics (1999), 200(3), 562-573

Previous kinetic studies concluded on the aggregation of the anionic chain ends of living tert-butyl methacrylate oligomers [PtBMA-, Li+] in THF at low temperature. This aggregation has been confirmed by ... [more ▼]

Previous kinetic studies concluded on the aggregation of the anionic chain ends of living tert-butyl methacrylate oligomers [PtBMA-, Li+] in THF at low temperature. This aggregation has been confirmed by viscosimetry, light scattering and gradient field NMR techniques in a range of temperature from 253 K to 298 K. These techniques have been systematically used for the analysis of both the living oligomers and the same chains recovered after hydrolysis of the anionic end groups. The structure of the growing anionic species was analyzed by means of 13C and 7Li NMR spectroscopy. 13C NMR required the selective labeling of the last monomer units by 13C atoms. [less ▲]

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See detailMicrodynamics of reverse micelles of ω- and α,ω-metal sulfonato polystyrene in toluene
Vanhoorne, Pierre ULg; Grandjean, Jean ULg; Jérôme, Robert ULg

in Macromolecules (1995), 28(10), 3553-3561

Reverse micelles of omega- and alpha,omega-metal sulfonato polystyrenes in toluene have been investigated by Li-6, Li-7, and pulsed field gradient NMR. Micelles are found to be of a narrow size ... [more ▼]

Reverse micelles of omega- and alpha,omega-metal sulfonato polystyrenes in toluene have been investigated by Li-6, Li-7, and pulsed field gradient NMR. Micelles are found to be of a narrow size distribution and to consist of roughly spherical ionic cores shielded from the solvent by a polystyrene shell. The nature of the ion pair is found to influence significantly the micellar size. The correlation time characteristic of lithium relaxation is faster than the reorientational correlation time of the aggregates, which means that lithium relaxation essentially takes place within the ionic cores. The effective relaxation mechanism is consistent with a fast exchange of lithium ions between different coordination sites within the aggregates. In concentrated solutions, the equilibrium between aggregated polymer chains and unassociated chains is essentially shifted toward the aggregated species. This tendency is reversed upon dilution. Below a critical micellar concentration of ca. 0.01 g/dL, only ''free'' chains persist in solution. Temperature has no significant effect on the position of the aggregation equilibrium. The aggregates are dissociated by the addition of a polar cosolvent, such as methanol, which solvates the ion pairs. The MeOH/Li+ molar ratio must, however, be higher than 100 to perturb significantly the ion pair aggregation. Up to a MeOH/Li+ ratio of 10 000, part of the chains remain aggregated, and the lithium spin-lattice relaxation is dominated by the aggregates. Above a MeOH/Li+ ratio of 10 000, the aggregates are almost completely disrupted. Self-diffusion coefficients of the difunctional chains are not dramatically smaller compared to the monofunctional counterparts, even when solutions of difunctional compounds form a gel. This behavior might be explained by the percolation model applied to the aggregation process, with the pulsed field NMR experiment probing only the selfdiffusion of the clusters in the sol phase of the gel. [less ▲]

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See detailEtude des flux de sodium dans les systèmes biologiques par résonance magnétique du sodium-23
Carlier, P. G.; Grandjean, Jean ULg; Gilles-Baillien, M. et al

in Groupe de contact FNRS (1983)

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See detailApplication de la RMN du Na 23 à l'étude des échanges ioniques
Carlier, P. G.; Grandjean, Jean ULg; GILLES-BAILLIEN, M. et al

in 2nd international symposium fundamentals of technical progress in medicine (1983)

One single line is usually observed in the Na NMR spectra of biological systems. Some anionic paramagnetic species interacting with the sodium shift the sodium signal. So long as it does not enter the ... [more ▼]

One single line is usually observed in the Na NMR spectra of biological systems. Some anionic paramagnetic species interacting with the sodium shift the sodium signal. So long as it does not enter the cell, a shift reagent splits the resonance line into two components: the intra (unshifted) and the extracellular Na (shifted). The method is applied to intestinal epithelium and to erythrocytes. Extracellular medium is enriched with dysprosium tripolyphosphate 2,5 mM. Na-K pump activity is studied in human erythrocytes. Ouabain (10 M) inhibition can be followed by the increase of the internal Na peak on the successive spectra whereas it does not change in the control. Na efflux out of the Na loaded erythrocytes can be measured as well. After incubation in a recovering medium, intracellular Na, as calculated from the successive spectra, returns progressively to normal. Simultaneously, the external peak shift reduces. This method can successfully demonstrate attenuations of the Na-K pump in pathological circumstances, such as chronic renal failure . The effects of polyether antibiotics on the sodium transport are also studied by this way. For instance, monensin causes a swift Na efflux that transiently broadens the external signal. Using shift reagent, Na NMR is an efficient tool for ionic membrane exchange studies. [less ▲]

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