15 research outputs found
Synthesis and characterisation of polyester from dimethylketene and carbonyled compounds
Lâobjectif de cette Ă©tude est de synthĂ©tiser et de caractĂ©riser des polyesters entre le dimĂ©thylcĂ©tĂšne et des composĂ©s carbonylĂ©s choisis (acĂ©tone, mĂ©thylĂ©thylcĂ©tone et acĂ©thaldĂ©hyde) par deux voies distinctes : une copolymĂ©risation directe, et une voie passant dâabord par la synthĂšse de la beta-lactone puis sa polymĂ©risation par ouverture de cycle. La caractĂ©risation a mis en Ă©vidence la structure parfaitement alternĂ©e du polyester entre le dimĂ©thylcĂ©tĂšne et lâacĂ©tone, et des structures plus complexes avec la mĂ©thylĂ©thylcĂ©tone et lâacĂ©taldĂ©hyde. Les analyses ont Ă©galement montrĂ© le caractĂšre polymorphe complexe de ces copolymĂšres. Les trois beta-lactones correspondantes ont Ă©galement Ă©tĂ© synthĂ©tisĂ©es. Seule la polymĂ©risation de la beta-lactone avec lâacĂ©taldĂ©hyde a Ă©tĂ© menĂ©e Ă bien, du fait de son faible encombrement stĂ©rique. Enfin, une Ă©tude cinĂ©tique par infrarouge a Ă©galement Ă©tĂ© effectuĂ©e et a permis de mieux connaĂźtre les cinĂ©tiques de polymĂ©risation par ouverture de cycle.The aim of this study is to synthesise and to characterise polyesters between dimethylketene and chosen carbonyled compounds (acetone, methylethylketone and acetaldehyde) by two distinct pathways: a direct copolymerisation, and another path proceeding in the synthesis of the beta-lactone then its ring opening polymerisation. The characterisation has highlighted the perfectly alternated structure of the polyester between dimethylketene and acetone, and more complex structures with dimethylketone and acetaldehyde. The analyses have also shown the complex polymorphism of these copolymers. The three corresponding beta-lactones have been synthesised. Only the polymerisation of the acetaldehyde beta-lactone has been accomplished because of its weak steric hindrance. At last, an infrared kinetic study has also been carried out and has permitted a better comprehension of the kinetic of the ring opening polymerisation
SynthÚse et caractérisation de polyesters à partir du diméthylcétÚne et de composés carbonylés
The aim of this study is to synthesise and to characterise polyesters between dimethylketene and chosen carbonyled compounds (acetone, methylethylketone and acetaldehyde) by two distinct pathways: a direct copolymerisation, and another path proceeding in the synthesis of the beta-lactone then its ring opening polymerisation. The characterisation has highlighted the perfectly alternated structure of the polyester between dimethylketene and acetone, and more complex structures with dimethylketone and acetaldehyde. The analyses have also shown the complex polymorphism of these copolymers. The three corresponding beta-lactones have been synthesised. Only the polymerisation of the acetaldehyde beta-lactone has been accomplished because of its weak steric hindrance. At last, an infrared kinetic study has also been carried out and has permitted a better comprehension of the kinetic of the ring opening polymerisation.Lâobjectif de cette Ă©tude est de synthĂ©tiser et de caractĂ©riser des polyesters entre le dimĂ©thylcĂ©tĂšne et des composĂ©s carbonylĂ©s choisis (acĂ©tone, mĂ©thylĂ©thylcĂ©tone et acĂ©thaldĂ©hyde) par deux voies distinctes : une copolymĂ©risation directe, et une voie passant dâabord par la synthĂšse de la beta-lactone puis sa polymĂ©risation par ouverture de cycle. La caractĂ©risation a mis en Ă©vidence la structure parfaitement alternĂ©e du polyester entre le dimĂ©thylcĂ©tĂšne et lâacĂ©tone, et des structures plus complexes avec la mĂ©thylĂ©thylcĂ©tone et lâacĂ©taldĂ©hyde. Les analyses ont Ă©galement montrĂ© le caractĂšre polymorphe complexe de ces copolymĂšres. Les trois beta-lactones correspondantes ont Ă©galement Ă©tĂ© synthĂ©tisĂ©es. Seule la polymĂ©risation de la beta-lactone avec lâacĂ©taldĂ©hyde a Ă©tĂ© menĂ©e Ă bien, du fait de son faible encombrement stĂ©rique. Enfin, une Ă©tude cinĂ©tique par infrarouge a Ă©galement Ă©tĂ© effectuĂ©e et a permis de mieux connaĂźtre les cinĂ©tiques de polymĂ©risation par ouverture de cycle
SynthÚse et caractérisation de polyesters à partir du diméthylcétÚne et de composés carbonylés
L objectif de cette étude est de synthétiser et de caractériser des polyesters entre le diméthylcétÚne et des composés carbonylés choisis (acétone, méthyléthylcétone et acéthaldéhyde) par deux voies distinctes : une copolymérisation directe, et une voie passant d abord par la synthÚse de la beta-lactone puis sa polymérisation par ouverture de cycle. La caractérisation a mis en évidence la structure parfaitement alternée du polyester entre le diméthylcétÚne et l acétone, et des structures plus complexes avec la méthyléthylcétone et l acétaldéhyde. Les analyses ont également montré le caractÚre polymorphe complexe de ces copolymÚres. Les trois beta-lactones correspondantes ont également été synthétisées. Seule la polymérisation de la beta-lactone avec l acétaldéhyde a été menée à bien, du fait de son faible encombrement stérique. Enfin, une étude cinétique par infrarouge a également été effectuée et a permis de mieux connaßtre les cinétiques de polymérisation par ouverture de cycle.The aim of this study is to synthesise and to characterise polyesters between dimethylketene and chosen carbonyled compounds (acetone, methylethylketone and acetaldehyde) by two distinct pathways: a direct copolymerisation, and another path proceeding in the synthesis of the beta-lactone then its ring opening polymerisation. The characterisation has highlighted the perfectly alternated structure of the polyester between dimethylketene and acetone, and more complex structures with dimethylketone and acetaldehyde. The analyses have also shown the complex polymorphism of these copolymers. The three corresponding beta-lactones have been synthesised. Only the polymerisation of the acetaldehyde beta-lactone has been accomplished because of its weak steric hindrance. At last, an infrared kinetic study has also been carried out and has permitted a better comprehension of the kinetic of the ring opening polymerisation.ROUEN-INSA Madrillet (765752301) / SudocSudocFranceF
Polyester obtained from dimethylketene and acetone: synthesis and characterization
International audienc
Impact of polymer Microstructure on theSelf-Assembly of Amphiphilic Polymers in Aqueous Solutions
International audienc
Dynamic modeling of in vitro lipid digestion: Individual fatty acid release and bioaccessibility kinetics
The aim of this study was to gain knowledge about the role of triacylglycerol (TAG) composition in fatty acids (FA) of o/w emulsions on both the pancreatic lipolysis kinetics and the bioaccessibility of released products (i.e. contained within the bile salt micellar phase). A mathematical model was developed and its predictions were compared to a set of experimental data obtained during an in vitro digestion of a whey protein stabilized emulsion. Modeling results show that FA residues of TAG were hydrolyzed at specific rates, inducing different bioaccessibility kinetics. The estimated lipolysis rate constants of the studied FA (C8:0, C10:0 >> C18:1 n-9 >> C12:0 > C14:0 > C16:0 approximate to C16:1 n-7 > C22:6 n-3) were in close agreement with the available literature on the substrate specificity of pancreatic lipase. Results also suggest that lipolysis products are very rapidly solubilized in the bile salt mixed micelles with no fractionation according to the FA carbon chain
In vitro digestion of a whey protein stabilized emulsion: Mechanistic modeling reveals the major influence of droplet coalescence on the kinetics of pancreatic lipolysis (poster)
International audienceno abstrac
Modeling the effects of emulsion coalescence and oil composition on in vitro digestion kinetics and fatty acid bioaccessibility (poster)
International audienceno abstrac
Dynamic modeling highlights the major impact of droplet coalescence on the in vitro digestion kinetics of a whey protein stabilized submicron emulsion
Submicron oil-in-water emulsions stabilized with whey proteins have been reported to be relatively resistant and highly sensitive to coalescence during the gastric and intestinal phases of in vitro digestion experiments, respectively. The aim of this study was to assess the impact of droplet coalescence on the intestinal lipolysis kinetics of such emulsion, and to develop a mathematical model able to predict the experimental observations. A submicron whey protein stabilized emulsion made of a mixture of medium-chain (MCT) and long-chain triacylglycerols (LCT) was prepared and submitted to gastrointestinal in vitro digestion. Triacylglycerol concentrations and droplet size distributions were measured before and after the gastric phase and during the intestinal phase using HPLC and laser granulometry, respectively. MCT were fully digested within 15 min of intestinal digestion, whereas LCT were still detected after 5 h. Moreover, the intestinal lipolysis of LCT showed a two-stage behavior with an initial fast rate that markedly slowed down after about 30 min, a time at which a sudden rise in the droplet sizes, attributed to coalescence, was also observed. A mathematical model based on the experimentally measured droplet sizes and assuming a rate of lipolysis proportional to the interfacial area was developed and successfully used to reproduce the observed kinetics. Our results support the idea that droplet coalescence during the intestinal phase was the main reason for the marked slowdown of the kinetics of lipid digestion, hence suggesting that other possible mechanisms, such as an inhibition of the lipolysis reaction, could only explain secondary order effects
Modeling in vitro digestion of emulsions: effects of droplet size and oil composition on lipolysis kinetics and fatty acid bioaccessible profiles (poster)
International audienceno abstrac