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International audience; Levoglucosan (LGA) is an anhydrous pyrolytic sugar that has gained increasing attention in recent years. The highest focus on the conversion of LGA and other anhydro carbohydrates obtained from cellulose aims at the valorization of these molecules and their application in multiple fields such as chemical and pharmaceutical industries. LGA presents a rigid structure with three hydroxyl groups on a pyranose ring, making it a promising building block for the synthesis of bio-based thermoplastic polymers with pending OH groups as soon as a regioselective polymerization is reached. In this work, a lipase-catalyzed series of LGA-containing terpolymers were synthesized for the first time via regioselective transesterification in two-stage polymerization. LGA was reacted with diethyl adipate/sebacate and α,ω-diols to give terpolymers with up to 35% of LGA content (related to the α,ω-diol content), number-average molecular weights (Mn) of up to 7900 g·mol–1, and up to 94% yield. It was observed that the amount of LGA in the polymer structure affects the crystallinity, hydrophilicity, and melting point of the polymers. We also evaluated the effect of LGA loading and the comonomer’s size on yields, molecular weight, and the incorporation of LGA in the polymer structure. High loads of LGA lead to a decrease in the yield, but a higher molecular weight and higher extent of LGA incorporation in the polymer can be obtained.

We developed a new hybrid material resulting from an innovative supramolecular tripartite association between an ionic liquid covalently immobilized on primary β-cyclodextrins rim and an anionic water-soluble polymer. Two hydrophilic ternary complexes based on native and permethylated β-cyclodextrins substituted with an ionic liquid and immobilized on poly(styrene sulfonate) (CD-IL+PSS− and CD(OMe)IL+PSS−) were obtained by simple dialysis with a cyclodextrin maximal grafting rate of 25% and 20% on the polymer, respectively. These polyelectrolytes are based on electrostatic interactions between the opposite charges of the imidazolium cation of the ionic liquid and the poly(styrene sulfonate) anion. The inclusion properties of the free cavities of the cyclodextrins and the synergic effect of the polymeric matrix were studied with three reference guests such as phenolphthalein, p-nitrophenol, and 2-anilinonaphthalene-6-sulfonic acid using UV-visible, fluorescent, and NMR spectroscopies. The support has been applied successfully in dialysis device to extract and concentrated aromatic model molecule. This simple and flexible synthetic strategy opens the way to new hybrid materials useful for fast and low-cost ecofriendly extraction techniques relevant for green analytical chemistry.

International audience; Furan-2,5-dicarboxylic acid has been introduced in recent years as a green aromatic monomer toward the design of aromatic (co)polyesters with enhanced properties, i.e., polyethylene furanoate (PEF) that can definitely compete with its petroleum-based counterpart, i.e., polyethylene terephthalate (PET). In an attempt to produce biobased semiaromatic copolyesters in an efficient eco-friendly approach, we report herein the polycondensation of diethyl furan-2,5-dicarboxylate (DEFDC) with different aliphatic diols and diesters of variable chain length catalyzed by an immobilized lipase from Candida antarctica using a two-step polymerization reaction carried out in diphenyl ether. The influence of diol and diester chain length, the molar concentration of DEFDC, and the effect of enzyme loading were assessed via nuclear magnetic resonance (NMR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and wide-angle X-ray scattering (WAXS). With high quantities of DEFDC, significant differences in terms of M̅n buildup were noticed. Only longer diols starting from octane-1,8-diol successfully reacted with up to 90% DEFDC as opposed to only 25% DEFDC reacting with short diols such as butane-1,4-diol. While varying the chain length of the diester, it was evident that shorter diols such as hexane-1,6-diol have better reactivity toward longer diesters, while dodecane-1,12-diol was reactive toward all tested diesters. The incorporation of long chain fatty dimer diols such as Pripol 2033 led to polyesters with higher M̅n and was successfully used to overcome the limitations of poor reactivity observed in the case of short diols in the presence of high furan content. The DSC results showed a pseudoeutectic behavior as a function of increasing the mol % of DEFDC, and a change in the crystalline phase was confirmed via WAXS analysis. Finally, this work showed the successful enzyme-catalyzed synthesis of several DEFDC biobased semiaromatic copolyesters with variable interesting properties that can be further optimized for possible applications in food packaging as well as other possibilities.; L'acide furane-2,5-dicarboxylique a été introduit ces dernières années en tant que monomère aromatique vert pour la conception de (co)polyesters aromatiques aux propriétés améliorées, comme le polyéthylène furanoate (PEF) qui peut définitivement concurrencer son homologue issu du pétrole, le polyéthylène téréphtalate (PET). Dans le but de produire des copolyesters semi-aromatiques d'origine biologique par une approche efficace et respectueuse de l'environnement, nous rapportons ici la polycondensation du furan-2,5-dicarboxylate de diéthyle (DEFDC) avec différents diols et diesters aliphatiques de longueur de chaîne variable, catalysée par une lipase immobilisée de Candida antarctica, en utilisant une réaction de polymérisation en deux étapes réalisée dans de l'éther diphénylique. L'influence de la longueur de chaîne des diols et des diesters, la concentration molaire de DEFDC, ainsi que l'effet de la charge enzymatique ont été évalués par Résonance Magnétique Nucléaire (RMN), chromatographie par perméation de gel (CPG), calorimétrie différentielle à balayage (DSC) et diffusion des rayons X à angle large (WAXS). Sans DEFDC, ou à faible teneur, l'augmentation de la longueur du diol n'a pas eu d'effet négatif sur la masse moléculaire moyenne en nombre (Mn) des copolyesters aliphatiques préparés. En revanche, lorsque des quantités élevées de DEFDC (plus de 40 % molaire) ont été ajoutées dans le milieu réactionnel, des différences significatives en termes d'accumulation de Mn ont été remarquées. Seuls les diols plus longs à partir de l'octane-1,8-diol ont été mis en réaction avec succès avec jusqu'à 90% de DEFDC, par opposition à seulement 25% de DEFDC avec des diols courts tels que le butane-1,4-diol. Le Mn obtenu a montré une tendance à diminuer en fonction de l'augmentation du % d'alimentation en DEFDC, surtout avec les diols courts où la diminution du Mn était plus prononcée. En faisant varier la longueur de la chaîne du diester, il était évident que les diols plus courts tels que l'hexane-1,6-diol ont une meilleure réactivité vis-à-vis des diesters plus longs, tandis que le dodécane-1,12-diol était réactif vis-à-vis de tous les diesters testés. L'incorporation de diols dimères gras à longue chaîne tels que le Pripol 2033 dans le milieu réactionnel a conduit à des polyesters avec un Mn plus élevé et a été utilisé avec succès pour surmonter les limitations de la faible réactivité observée dans le cas des diols courts en présence d'une teneur élevée en furanes. Les résultats de la calorimétrie différentielle à balayage (DSC) ont montré un comportement pseudo-eutectique caractérisé par une diminution du point de fusion (Tm) en fonction de l'augmentation du % molaire de DEFDC, suivie d'une augmentation à un % molaire plus élevé deࣙࣙ DEFDC (≥ 50%) et un changement de la phase cristalline confirmé par une analyse de diffusion des rayons X à grand angle (WAXS). Enfin, ce travail a montré la synthèse réussie par catalyse enzymatique de plusieurs copolyesters semi-aromatiques biosourcés avec des propriétés intéressantes variables, à base de DEFDC.

International audience; Surface modification of cellulose nanocrystals (CNC) by organocatalysed grafting from ring-opening polymerization (ROP) of trimethylene carbonate was investigated. Organocatalysts including an amidine (DBU), a guanidine (TBD), an amino-pyridine (DMAP) and a phosphazene (BEMP) were successfully assessed for this purpose, with performances in the order TBD > BEMP > DMAP, DBU. The grafting ratio can be tuned by varying the experimental parameters, with the highest grafting of 74 % by weight obtained under mild conditions, i.e at roomtemperature in tetrahydrofuran with a low amount of catalyst. This value is much higher than that of typical ring opening polymerizations of cyclic esters initiated from the surface of cellulose nanoparticles. Additionally, DSC analysis of the modified material revealed the presence of a glass transition temperature, indicative of a sufficient graft length to display polymeric behaviour. This is, to our knowledge, the first example of cellulose nanocrystalsgrafted with polycarbonate chains.; La modification de surface des nanocristaux de cellulose (CNC) par greffage organocatalysé à partir de la polymérisation par ouverture de cycle (ROP) du carbonate de triméthylène a été étudiée. Des organocatalyseurs comprenant une amidine (DBU), une guanidine (TBD), une amino-pyridine (DMAP) et un phosphazène (BEMP) ont été évalués avec succès dans ce but, avec des performances dans l'ordre TBD > BEMP > DMAP, DBU. Le taux de greffage peut être ajusté en faisant varier les paramètres expérimentaux, le greffage le plus élevé de 74 % en poids ayant été obtenu dans des conditions douces, c'est-à-dire à température ambiante dans du tétrahydrofurane avec une faible quantité de catalyseur. Cette valeur est beaucoup plus élevée que celle des polymérisations par ouverture de cycle typiques des esters cycliques initiées à partir de la surface des nanoparticules de cellulose. De plus, l'analyse DSC du matériau modifié a révélé la présence d'une température de transition vitreuse, indiquant une longueur de greffe suffisante pour présenter un comportement polymère. Il s'agit, à notre connaissance, du premier exemple de nanocristaux de cellulose greffés avec des chaînes de polycarbonate.

International audience; Starch based materials are attractive bio-based alternative to fully synthetic polymers. Native starch has however limited thermoprocessability and properties and must be modified. In order to improve the properties of starch-graft-poly(butyl-acrylate-co-styrene) copolymers via a process as green as possible, we report herein a new method for the dual functionalization of the polysaccharide via a one pot one step reaction in aqueous medium combining free radical polymerizations and ring-opening chemistry. Poly(butyl acrylate) / poly(butyl acrylate-co-styrene) (ca. 60 000 g/mol) and oligo(-caprolactone) were grafted on starch with a grafting percentage up to 75 %. The copolymers show two glass transition temperatures: one around 55-60°C related to starch and a second attributed to the grafted vinyl polymers, from -46°C to 20°C depending on butyl acrylate/styrene ratio). The resulting dual functionalized materials exhibit excellent mechanical properties, with elongation at break in the range 20-210 %, while single functionalized starch shows less than 5 %.

International audience; Research toward bio-based polymers is an expanding field due to environmental concerns. A library of new aliphatic diol-diamide monomers with different chain lengths between the two amido groups was synthesized from sustainable levulinic acid and various linear aliphatic diamines (C 2-C 10). The monomers were prepared by diacylation of the diamines followed by reduction of the ketones to alcohols. These secondary diols were successfully recognized by an enzyme and polymerised in solution through a lipase-catalysed polycondensation. Poly(ester-co-amide)s with number-average molecular weights (M n) in the range of 1300-7200 g mol −1 were obtained, with dispersities between 1.5 and 1.8. An improvement of the M n value was observed upon increasing the monomer chain length. The variation of the aliphatic diol allows modulating the thermal properties of the final polymers. The glass transition temperatures were found to be between −23°C and 0°C. The polymers containing a long aliphatic segment (C 8-C 10) were able to crystallize (melting temperature of 90-97°C). TGA analyses showed that the ester linkages degrade at lower temperatures than the amide bonds. The stability of the latter was found to be higher when the number of methylene units increased from 2 (355°C) to 10 (378°C). This kind of biopolymer could be used as a drug delivery system or for tissue engineering applications. † Electronic supplementary information (ESI) available. See

The epimerization of polylactide is reported in the presence of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at 105°C in toluene. The extent of the reaction depends on the amount of TBD introduced and the reaction time. Up to ca. 46% D units can be formed starting from poly(L-lactide) in the presence of 5 mol% TBD. The epimerization rate is slightly higher for D-stereoisomers vs. L-stereoisomers. From the decrease of the number-average molecular weight observed, a concomitant chain scission reaction is observed. A possible mechanism based on a nucleophilic attack of TBD is proposed based on NMR analyses, notably DOSY, MALDI ToF mass spectrometry and IR spectroscopy. The implications of the work in the field of polymer synthesis and chemical recycling of polylactide are discussed. 181;109188

Among the various catalysts that can be used for polycondensation reactions, enzymes have been gaining interest for three decades, offering a green and eco-friendly platform towards the sustainable design of renewable polyesters. However, limitations imposed by their delicate nature, render them less addressed. As a case study, we compare herein bulk and solution polycondensation of 1,6-hexanediol and diethyl adipate catalyzed by an immobilized lipase from Candida antarctica. The influence of various parameters including time, temperature, enzyme loading, and vacuum was assessed in the frame of a two-step polymerization with the help of response surface methodology, a statistical technique that investigates relations between input and output variables. Results in solution (diphenyl ether) and bulk conditions showed that a two-hour reaction time was enough to allow adequate oligomer growth for the first step conducted under atmospheric pressure at 100 &deg, C. The number-average molecular weight (Mn) achieved varied between 5000 and 12,000 g&middot, mol&minus, 1 after a 24 h reaction and up to 18,500 g∙mol&minus, 1 after 48 h. The statistical analysis showed that vacuum was the most influential factor affecting the Mn in diphenyl ether. In sharp contrast, enzyme loading was found to be the most influential parameter in bulk conditions. Recyclability in bulk conditions showed a constant Mn of the polyester over three cycles, while a 17% decrease was noticed in solution. The following work finally introduced a statistical approach that can adequately predict the Mn of poly(hexylene adipate) based on the choice of parameter levels, providing a handy tool in the synthesis of polyesters where the control of molecular weight is of importance.

International audience; Organocatalysis has provided new tools for making block copolymers, in particular active species able to polymerize monomers of different chemical nature such as cyclic esters, cyclic carbonates and epoxides. We report herein the first example of an organocatalytic active species able to polymerize sequentially a cyclic ester, ε-decalactone, and a vinyl monomer, methyl methacrylate. The resulting block copolymer shows the properties of thermoplastic elastomers.