59 research outputs found
Characterization of poly(ethylene oxide) and polystyrene based block copolymers by advanced high performance liquid chromatography techniques
DiffĂ©rentes techniques de chromatographie liquide des polymĂšres ont Ă©tĂ© Ă©tudiĂ©es selon leur principe dâĂ©lution et le comportement conformationnel des polymĂšres suscitĂ© au sein de la phase stationnaire. De part leur capacitĂ© Ă caractĂ©riser des copolymĂšres Ă blocs, la Chromatographie Liquide aux Conditions Critiques (LC CC) et la Chromatographie Liquide aux Conditions Limites de DĂ©sorption (LC LCD) ont Ă©tĂ© utilisĂ©es pour dĂ©terminer la composition chimique de copolymĂšres Ă blocs Ă base de poly(oxyde dâĂ©thylĂšne) et de polystyrĂšne. La LC LCD sâest distinguĂ©e par sa capacitĂ© Ă sĂ©parer de maniĂšre efficace les copolymĂšres Ă blocs de leurs homopolymĂšres parents. Cette mĂ©thode chromatographique a ensuite Ă©tĂ© optimisĂ©e afin dâĂȘtre appliquĂ©e Ă une plus large gamme de masses molaires.Several advanced techniques of liquid chromatography of polymers were studied according to their elution principle and the conformational behaviour of polymers along the stationary phase. Because of their potential to characterize block copolymers, Liquid Chromatography under Critical Conditions (LC CC) and Liquid Chromatography under Limiting Conditions of Desorption (LC LCD) were employed to determine the chemical composition of Poly(ethylene oxide) and Polystyrene based block copolymers. Interestingly, LC LCD was proved to be particularly efficiently to separate block copolymers from both their parent homopolymers. LC LCD method was then optimized to extend the applicable molar masses ranges
"Michael addition" reaction onto vinyl sulfonyl(trifluoromethylsulfonyl) imide: An easy access to sulfonyl(trifluoromethylsulfonyl)imide-based monomers and polymers
WOS:000450376300009Sulfonyl(trifluoromethylsulfonyl) imide anion (STFSI, -SO2N(-)SO2CF3) is one of the most important sulfonimide groups for organic and material synthesis. However, the synthesis of STFSI-functionalized monomers and related polymers is still a problematic issue, comprising multi-step and complex synthetic processes. To overcome this drawback, we developed a robust and versatile strategy to prepare original STFSI-based monomers using the "Michael addition" reaction conducted in the presence of vinyl sulfonyl(trifluoromethylsulfonyl)imide and either an amine or a malonate derivative. Furthermore, the synthesized monomers were used to prepare the corresponding STFSI-functionalized polymers using step-growth polymerization with potential applications as electrolytes
A post-polymerization functionalization strategy for the synthesis of sulfonyl (trifluoromethanesulfonyl)imide functionalized (co)polymers
International audienc
Radical Chain End Chemical Transformation of SG1-Based Polystyrenes
International audienceRadical chain end functionalization of polystyrene previously prepared by NMP using the SG1 nitroxide was investigated. Hydroxy-functional polystyrenes were easily prepared by two different pathways: via an exchange with TEMPO nitroxide followed by a Zn/AcOH reduction or via a radical hydroxylation using the in situ preparation/reduction of the corresponding hydroperoxide. The introduction of a bromine end group was performed by radical bromination under mild conditions using ethyl 2-bromoisobutyrate as bromine transfer agent. The latter polymer was further reacted with NaN3 and also used as a macroinitiator to prepare PS-b-PMMA by ATRP to confirm the chemical post-transformation. Azide-functional polystyrenes were also prepared by a one-step radical azidation reaction using ethanesulfonyl azide. In all cases, the chemical transformations were followed by both liquid chromatography at the critical condition in pure eluent and Maldi-Tof MS
Phosphonate-Functionalized Polycarbonates Synthesis through Ring-Opening Polymerization and Alternative Approaches
Well-defined phosphonate-functionalized polycarbonate with low dispersity (Ă = 1.22) was synthesized using organocatalyzed ring-opening polymerization (ROP) of novel phosphonate-based cyclic monomers. Copolymerization was also performed to access different structures of phosphonate-containing polycarbonates (PC). Furthermore, phosphonate-functionalized PC was successfully synthesized using a combination of ROP and post-modification reaction
Separation of parent homopolymers from polystyrene and poly(ethylene oxide) based block copolymers by liquid chromatography under limiting conditions of desorption-3. Study of barrier efficiency according to block copolymers' chemical composition
International audienceLiquid Chromatography under Limiting Conditions of Desorption (LC LCD) is a powerful separation tool for multicomponent polymer systems. This technique is based on a barrier effect of an appropriate solvent, which is injected in front of the sample, and which decelerates the elution of selected macromolecules. In this study, the barrier effects have been evaluated for triblock copolymers polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) according to the content of polystyrene (wt% PS) and PEO-block molar mass. PS-b-PEO-b-PS samples were prepared by Atom Transfer Radical Polymerization (ATRP). The presence of respective parent homopolymers was investigated by applying optimized LC LCD conditions. It was found that the barrier composition largely affects the efficiency of separation and it ought to be adjusted for particular composition range of block copolymers. (C) 2016 Elsevier B.V. All rights reserved
Relations entre proximitĂ© Ă un marchĂ© alimentaire et approvisionnements en fruits et lĂ©gumes dans lâĂ©tude MontâPanier
International audienceIntroduction et but de lâĂ©tude : Le paysage alimentaire, qui peut se dĂ©finir comme lâensemble des lieux oĂč il est possible de se procurer des aliments pour une population sur un territoire donnĂ©, est un dĂ©terminant des comportements dâachats alimentaires rarement Ă©tudiĂ© en France. Les marchĂ©s alimentaires pourraient ĂȘtre un levier pour une alimentation plus durable, en favorisant une production locale et les circuits courts et en proposant des produits de bonne qualitĂ© Ă des prix abordables. Pourtant, les rares Ă©tudes disponibles ne prennent pas en considĂ©ration ces lieux dâachats alimentaires. Lâobjectif de notre Ă©tude Ă©tait dâĂ©valuer les associations entre la proximitĂ© Ă un marchĂ© et dâune part, la part des dĂ©penses en fruits et lĂ©gumes et dâautre part, la frĂ©quentation dâun marchĂ©.MatĂ©riel et mĂ©thodes : Les analyses portent sur un Ă©chantillon de 409 mĂ©nages de la MĂ©tropole de Montpellier issus de lâĂ©tude transversale MontâPanier. Les caractĂ©ristiques socioĂ©conomiques des mĂ©nages ont Ă©tĂ© collectĂ©es grĂące Ă un questionnaire en ligne et leurs dĂ©penses alimentaires ont Ă©tĂ© estimĂ©es par un carnet dâapprovisionnement alimentaire combinĂ© Ă une collecte de tickets de caisse dâun mois. La proximitĂ© dâun marchĂ©, i.e. distance la plus courte entre les lieux de rĂ©sidence ou dâactivitĂ© principale des mĂ©nages et le marchĂ© le plus proche, a Ă©tĂ© calculĂ©e en utilisant un systĂšme dâinformation gĂ©ographique. Les associations entre proximitĂ© et part des dĂ©penses en fruits et lĂ©gumes, ainsi que frĂ©quentation dâun marchĂ© (oui/non), ont Ă©tĂ© Ă©valuĂ©es avec des modĂšles multiniveaux ajustĂ©s sur les variables socioĂ©conomiques. Lâassociation entre la frĂ©quentation dâun marchĂ© et la part des dĂ©penses en fruits et lĂ©gumes a Ă©tĂ© Ă©valuĂ©e avec des modĂšles linĂ©aires ajustĂ©s.RĂ©sultats et Analyse statistique : Les mĂ©nages dont le marchĂ© le plus proche de leurs lieux de vie Ă©tait entre 500 et 1000m (ÎČ= -0.61 (0.26) ; p= 0.02) et ceux dont le marchĂ© le plus proche Ă©tait Ă plus de 1000m (ÎČ -1.42 (0.30) ; p= <.0001) Ă©taient moins susceptibles de frĂ©quenter un marchĂ©, que ceux dont le marchĂ© le plus proche Ă©tait Ă moins de 500m. Les mĂ©nages dont le marchĂ© le plus proche Ă©tait Ă une distance entre 500 et 1000m (ÎČ= -9.50 (4.10) ; p= 0.02) et ceux dont le marchĂ© le plus proche Ă©tait Ă une distance de plus de 1000m (ÎČ= -9.81 (3.89) ; p= 0.01), avaient une part de dĂ©penses en fruits et lĂ©gumes plus faible que ceux dont le marchĂ© le plus proche Ă©tait Ă moins de 500m. Enfin, la frĂ©quentation dâun marchĂ© Ă©tait associĂ©e Ă une plus grande part des dĂ©penses en fruits et lĂ©gumes (ÎČ=9.81 (3.70) ; p=0.01).Conclusion : La proximitĂ© Ă un marchĂ© est associĂ©e Ă une part des dĂ©penses en fruits et lĂ©gumes plus importante, probablement via une plus grande frĂ©quentation de marchĂ©s. Des analyses supplĂ©mentaires seront rĂ©alisĂ©es afin dâĂ©valuer les facteurs mĂ©diateurs qui contribuent Ă expliquer ces associations. Ces rĂ©sultats pourront guider les politiques urbaines Ă mettre en oeuvre les actions appropriĂ©es pour amĂ©liorer le paysage alimentaire des villes en vue dâune alimentation plus saine et durable
Associations between food environment around home and overweight and obesity rates in French adults
International audienc
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