Organogels from trehalose difatty esters amphiphiles

International audienceSaccharide diesters have been recently shown to be excellent gelators of vegetable oils. In this paper, different fatty acid trehalose diesters were synthesized by a selective enzymatic transesterification performed only on the primary hydroxyl group of the trehalose. The resulting trehalose diesters demonstrated their ability to self-assemble in a large variety of edible vegetable oils with a minimum gelation concentration of 0.25 wt%/v. Microscopic analysis and X-ray scattering studies indicate that the gels are obtained by the self-assembly of trehalose diesters in crystalline fibers constituting the tridimensional network. The rheological study revealed that the properties of the gels depend on the kind of fatty acid grafted on the trehalose but are also influenced by the vegetable oil composition

Glycolipides : de la synthèse et l’étude de l’auto-assemblage à la conception de polymères bio-sourcés originaux

The aim of this thesis was to study glycolipids and particularly trehalose esters for the synthesis of new bio-sourced polymers. Trehalose monoesters and diesters were synthesized by two esterification pathways of the primary alcohol of trehalose with different fatty acids. The first synthetic route is a protective group-free esterification using a peptide coupling agent and the second one is a lipase-catalyzed esterification. The self-assembly properties of the trehalose esters were investigated. Trehalose monoesters showed surfactant properties in water and trehalose monoerucate was even able to form gels in water. The trehalose diesters appeared to be good gelators for organic solvent and vegetable oil. Thus, gels in three vegetable oils were prepared and their morphology and rheological properties were studied. Afterwards, trehalose diesters were functionalized and polymerized with different strategies.Thus, polyurethanes and poly(hydroxyurethane)s were obtained by polycondensation where as glyco-polyesters were synthesized by acyclic diene metathesis (ADMET) and thiol-enepolymerization. Finally, the self-assembly properties of these polymers were investigated. The latter were able to form some nanoparticles by solvent displacement method.Ces travaux de thèse traitent de l’étude de glycolipides et plus précisément d’esters de trehalose pour la synthèse de nouveaux polymères bio-sourcés. Des monoesters et diesters de trehalose ont ainsi été synthétisés par estérification des alcools primaires du trehalose avec des acides gras selon deux voies de synthèse. La première utilisant un agent de couplage peptidique ne nécessite pas l’utilisation de groupement protecteur pour estérifier sélectivement les alcools primaires. La deuxième est une estérification sélective catalysée par une lipase. L’auto-assemblage des esters de tréhalose a ensuite été étudié. Les monoesters possèdent des propriétés tensio-actives dans l’eau et le trehalose monoeruçate a la capacité de gélifier l’eau. Les diesters, quant à eux sont de bons gélifiants pour les solvants organiques etles huiles végétales. Par conséquent, des gels ont été préparés dans trois huiles végétales, puis leur morphologie et leur propriété rhéologique ont été étudiées. Ensuite, les diesters ont été fonctionnalisé et polymérisés selon différentes stratégies. Ainsi, des polyuréthanes et des poly(hydroxyuréthane)s ont été synthétisés par polycondensation tandis que des glycopolyesters ont été obtenus par polymérisation par métathèse et addition thiol-ène. Finalement,les propriétés d’auto-assemblage de ces polymères ont été étudiées. Ces derniers peuvent former des nanoparticules par la méthode de déplacement de solvants

Glycolipids : from synthesis and self-assembly studies to the design of original bio-based polymers

Ces travaux de thèse traitent de l’étude de glycolipides et plus précisément d’esters de trehalose pour la synthèse de nouveaux polymères bio-sourcés. Des monoesters et diesters de trehalose ont ainsi été synthétisés par estérification des alcools primaires du trehalose avec des acides gras selon deux voies de synthèse. La première utilisant un agent de couplage peptidique ne nécessite pas l’utilisation de groupement protecteur pour estérifier sélectivement les alcools primaires. La deuxième est une estérification sélective catalysée par une lipase. L’auto-assemblage des esters de tréhalose a ensuite été étudié. Les monoesters possèdent des propriétés tensio-actives dans l’eau et le trehalose monoeruçate a la capacité de gélifier l’eau. Les diesters, quant à eux sont de bons gélifiants pour les solvants organiques etles huiles végétales. Par conséquent, des gels ont été préparés dans trois huiles végétales, puis leur morphologie et leur propriété rhéologique ont été étudiées. Ensuite, les diesters ont été fonctionnalisé et polymérisés selon différentes stratégies. Ainsi, des polyuréthanes et des poly(hydroxyuréthane)s ont été synthétisés par polycondensation tandis que des glycopolyesters ont été obtenus par polymérisation par métathèse et addition thiol-ène. Finalement,les propriétés d’auto-assemblage de ces polymères ont été étudiées. Ces derniers peuvent former des nanoparticules par la méthode de déplacement de solvants.The aim of this thesis was to study glycolipids and particularly trehalose esters for the synthesis of new bio-sourced polymers. Trehalose monoesters and diesters were synthesized by two esterification pathways of the primary alcohol of trehalose with different fatty acids. The first synthetic route is a protective group-free esterification using a peptide coupling agent and the second one is a lipase-catalyzed esterification. The self-assembly properties of the trehalose esters were investigated. Trehalose monoesters showed surfactant properties in water and trehalose monoerucate was even able to form gels in water. The trehalose diesters appeared to be good gelators for organic solvent and vegetable oil. Thus, gels in three vegetable oils were prepared and their morphology and rheological properties were studied. Afterwards, trehalose diesters were functionalized and polymerized with different strategies.Thus, polyurethanes and poly(hydroxyurethane)s were obtained by polycondensation where as glyco-polyesters were synthesized by acyclic diene metathesis (ADMET) and thiol-enepolymerization. Finally, the self-assembly properties of these polymers were investigated. The latter were able to form some nanoparticles by solvent displacement method

Glycolipids : from synthesis and self-assembly studies to the design of original bio-based polymers

Ces travaux de thèse traitent de l’étude de glycolipides et plus précisément d’esters de trehalose pour la synthèse de nouveaux polymères bio-sourcés. Des monoesters et diesters de trehalose ont ainsi été synthétisés par estérification des alcools primaires du trehalose avec des acides gras selon deux voies de synthèse. La première utilisant un agent de couplage peptidique ne nécessite pas l’utilisation de groupement protecteur pour estérifier sélectivement les alcools primaires. La deuxième est une estérification sélective catalysée par une lipase. L’auto-assemblage des esters de tréhalose a ensuite été étudié. Les monoesters possèdent des propriétés tensio-actives dans l’eau et le trehalose monoeruçate a la capacité de gélifier l’eau. Les diesters, quant à eux sont de bons gélifiants pour les solvants organiques etles huiles végétales. Par conséquent, des gels ont été préparés dans trois huiles végétales, puis leur morphologie et leur propriété rhéologique ont été étudiées. Ensuite, les diesters ont été fonctionnalisé et polymérisés selon différentes stratégies. Ainsi, des polyuréthanes et des poly(hydroxyuréthane)s ont été synthétisés par polycondensation tandis que des glycopolyesters ont été obtenus par polymérisation par métathèse et addition thiol-ène. Finalement,les propriétés d’auto-assemblage de ces polymères ont été étudiées. Ces derniers peuvent former des nanoparticules par la méthode de déplacement de solvants.The aim of this thesis was to study glycolipids and particularly trehalose esters for the synthesis of new bio-sourced polymers. Trehalose monoesters and diesters were synthesized by two esterification pathways of the primary alcohol of trehalose with different fatty acids. The first synthetic route is a protective group-free esterification using a peptide coupling agent and the second one is a lipase-catalyzed esterification. The self-assembly properties of the trehalose esters were investigated. Trehalose monoesters showed surfactant properties in water and trehalose monoerucate was even able to form gels in water. The trehalose diesters appeared to be good gelators for organic solvent and vegetable oil. Thus, gels in three vegetable oils were prepared and their morphology and rheological properties were studied. Afterwards, trehalose diesters were functionalized and polymerized with different strategies.Thus, polyurethanes and poly(hydroxyurethane)s were obtained by polycondensation where as glyco-polyesters were synthesized by acyclic diene metathesis (ADMET) and thiol-enepolymerization. Finally, the self-assembly properties of these polymers were investigated. The latter were able to form some nanoparticles by solvent displacement method

ADMET polymerization of α,ω-unsaturated glycolipids: synthesis and physico-chemical properties of the resulting polymers

Trehalose diesters exhibiting α,ω-unsaturation are glycolipids which can be easily polymerized by ADMET (acyclic diene metathesis) polymerization. In this paper, enzymatic esterification was performed to selectively esterify primary hydroxyl groups of trehalose (6 and 6'-positions) with vinyl undecenoate. The vinyl ester was beforehand obtained by palladium-catalyzed transesterification of undecenoic acid with vinyl acetate. The resulting trehalose diundecenoate was homopolymerized and copolymerized with undecenyl undecenoate in order to obtain random copolymers with different compositions. The synthesis of such copolymers was confirmed by 1 H NMR spectroscopy and size exclusion chromatography (SEC). Their solid-state phase separation were investigated by DSC and X-ray scattering as function of temperature and their solution self-assembly was investigated by dynamic light scattering (DLS) in water

A thioglycerol route to bio-based bis-cyclic carbonates: poly(hydroxyurethane) preparation and post-functionalization

The present work is dedicated to the design of novel sulfur-substituted cyclic carbonates from thioglycerol, fatty acids and sugar derivatives. In this methodology, a sulfur atom is inserted in the β position of 5-membered ring cyclic carbonates via a two-step synthesis including the thiol–ene coupling of thioglycerol on fatty acid derivatives, followed by a transcarbonation. A similar strategy was adopted to prepare glycolipid-based cyclic carbonates in order to bring biodegradability to the final poly(hydroxyurethane)s. The so-formed monomers were characterized by NMR spectroscopies, HPLC and DSC. The enhanced reactivity of sulfur-substituted cyclic carbonates was demonstrated through a 1H NMR spectroscopy kinetic study of a model reaction with hexylamine. Fatty acid- and glycolipid-based sulfur-substituted bis-cyclic carbonates were then polymerized with diamines in a solvent using a catalyst-free process. FTIR, NMR, SEC, DSC and TGA were performed to investigate the PHUs’ chemical structure, molar masses and thermal properties. Finally, the so-formed PHUs were post-functionalized by sulfonation with m-CPBA taking advantage of thioether functions. The impact of the chemical modification was mostly studied on the polymer solubility and thermal stability

Bio-based aliphatic primary amines from alcohols through the ‘Nitrile route’ towards non-isocyanate polyurethanes

Bio-based primary amines obtained from the corresponding alcohols via nitrile intermediates and their subsequent polymerizations with cyclic carbonates are described. Nitrile compounds were synthesized under mild aerobic oxidation of primary aliphatic alcohols. CuI, bipyridine and TEMPO were used as a catalytic system, in the presence of aqueous ammonia and O2. A series of bio-sourced alcohols were successfully oxidized into nitriles using this catalytic system. The so-formed bio-based dinitriles were subsequently reduced into primary diamines under H2 in the presence of Ni Raney. The latter were polymerized with fatty acid-based bis-cyclic carbonates for the design of fully bio-based poly(hydroxyurethane)s

Analysis and Modelling of Extrusion Foaming Behaviour of Low-Density Polyethylene using Isobutane and CO2

In this work, modelling of physical foaming extrusion of LDPE is carried out in order to achieve a better understanding of the mechanisms involved in foam manufacturing. Foaming by extrusion is a four-step process. First, the pellets are introduced and molten in an extruder. Gas is then injected under pressure and dissolved in the polymer matrix. The mixture is then significantly cooled to give more strength to the material while maintaining a certain level of pressure. Finally, foam expansion occurs at the die exit. At this location, the dissolved gas undergoes a strong decompression leading to the nucleation and growth of bubbles. The objective of this study is to better understand the origin of the limitation of foaming based on the combination of an experimental analysis of the foaming process and the prediction of a model.The modelling tools are focused on the expansion occurring at the die exit, in order to quantify all the important parameters for the control of the foaming structure. The model, labelled as “cell model”, is based on previous works [1,2] and considers the growth of a single bubble in a mixture of polymer matrix and dissolved gas (blowing agent) [3]. In order to take into consideration the viscoelastic character of the polymer, the rheological behaviour is represented by a multi-Maxwell model.The foaming behaviour of two LDPE commercial grades provided by Total Research & Technology Feluy (Belgium) is compared for two different foaming agents (isobutane and carbon dioxide). The extrudate expansion at the die exit is analysed experimentally for different conditions (mainly temperature and gas concentration). An analysis of the extrusion parameters is performed to determine the quantity of dissolved gas which is effectively used for the foaming process. In order to compare with the experimental results, the cell model considers the gas concentration and the relaxation spectrum of each LDPE grade. As a consequence, particular attention is devoted to the determination of the solubility and the diffusivity of the blowing agent in the molten polymer based on literature data. The main effort concerns the analysis of the influence of the rheological properties of the two LDPE grades and the properties of the blowing agent on the size and stability of the cells. The modelling predictions are compared with the foam expansion and the foam density, revealing that the use of the cell model provides an accurate estimation of the final properties of the foam in the case of isobutane. The difference in final foam density is used to make hypotheses on the physical phenomena which can limit the foam expansion. Indeed, gas loss or polymer crystallization can limit the foam expansion and this is related to the temperature at the die exit [4]. Nevertheless, there is an open question on the role of strain hardening behaviour on foam expansion [3,5]. These different hypotheses will be discussed. REFERENCES[1] Reglero Ruiz, J.A., Vincent, M., Agassant, J.‐F., Claverie, A. and Huck, S. (2015), Morphological analysis of microcellular PP produced in a core‐back injection process using chemical blowing agents and gas counter pressure. Polym Eng Sci, 55: 2465-2473.[2] Reglero Ruiz, J.A., Vincent, M. and Agassant, J.‐F. (2016). Numerical Modeling of Bubble Growth in Microcellular Polypropylene Produced in a Core-Back Injection Process Using Chemical Blowing Agents, Int. Polym. Proc., 31: 26-36.[3] Otsuki, Y. and Kanai, T. (2005), Numerical simulation of bubble growth in viscoelastic fluid with diffusion of dissolved foaming agent. Polym Eng Sci, 45: 1277-1287.[4] Naguib, H.E., Park, C.B. and Reichelt, N. (2004), Fundamental foaming mechanisms governing the volume expansion of extruded polypropylene foams. J. Appl. Polym. Sci., 91: 2661-2668.[5] Weingart, N., Raps, D., Lu, M., Endner, L. and Altstädt, V. (2020). Comparison of the Foamability of Linear and Long-Chain Branched Polypropylene—The Legend of Strain-Hardening as a Requirement for Good Foamability. Polymers, 12(3):725

Extrusion moussage de polypropylènes linéaires et branchés - apport de l'analyse thermomécanique de la pression dans la filère

International audienceThis paper aims at a better understanding of the polypropylene (PP) physical extrusion foaming process with the objective of obtaining the lowest possible foam density. Two branched PPs were compared to the corresponding linear ones. Their shear and elongation viscosities were measured as well as their crystalline properties. Trials were conducted in a single screw extruder equipped with a gear pump and a static mixer cooler to adjust the melt temperature at the final die. The effect of decreasing this temperature on the PP foamability and on the pressure drop in the die was analyzed. The foam density of branched PPs varies from high to low values while decreasing the foaming temperature. In the same processing conditions, the foam density of linear PPs does not decrease so much, as already evidenced in the literature. The foamability transition coincides with an increase of the pressure drop in the die. The originality of the work lies in the thermomechanical analysis of the polymer flow in the die which allows the identification of the relevant physical phenomena for a good foamability. The comparison of the experimental pressure drops in the die and the computed ones with the identified purely viscous behavior points out the influence of the foaming temperature and of the PP structure. At high foaming temperature the discrepancy between experimental measurements and the computed pressure drops remains limited. It increases when decreasing the foaming temperature, but the mismatch is much more important for branched PPs than for linear ones. This difference is analyzed as a combination of the activation energy of the viscosity, the elongational viscosity in the convergent geometry of the die which is much more important for branched PPs than for linear ones, and the onset of crystallization which occurs at higher temperature for branched PPs than for linear PPs