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Background: An accurate estimation of the risk of life-threatening (LT) ventricular tachyarrhythmia (VTA) in patients with LMNA mutations is crucial to select candidates for implantable cardioverter-defibrillator implantation. Methods: We included 839 adult patients with LMNA mutations, including 660 from a French nationwide registry in the development sample, and 179 from other countries, referred to 5 tertiary centers for cardiomyopathies, in the validation sample. LTVTA was defined as (1) sudden cardiac death or (2) implantable cardioverter defibrillator–treated or hemodynamically unstable VTA. The prognostic model was derived using the Fine-Gray regression model. The net reclassification was compared with current clinical practice guidelines. The results are presented as means (SD) or medians [interquartile range]. Results: We included 444 patients, 40.6 (14.1) years of age, in the derivation sample and 145 patients, 38.2 (15.0) years, in the validation sample, of whom 86 (19.3%) and 34 (23.4%) experienced LTVTA over 3.6 [1.0–7.2] and 5.1 [2.0–9.3] years of follow-up, respectively. Predictors of LTVTA in the derivation sample were: male sex, nonmissense LMNA mutation, first degree and higher atrioventricular block, nonsustained ventricular tachycardia, and left ventricular ejection fraction (https://lmna-risk-vta.fr). In the derivation sample, C-index (95% CI) of the model was 0.776 (0.711–0.842), and the calibration slope 0.827. In the external validation sample, the C-index was 0.800 (0.642–0.959), and the calibration slope was 1.082 (95% CI, 0.643–1.522). A 5-year estimated risk threshold ≥7% predicted 96.2% of LTVTA and net reclassified 28.8% of patients with LTVTA in comparison with the guidelines-based approach. Conclusions: In comparison with the current standard of care, this risk prediction model for LTVTA in laminopathies significantly facilitated the choice of candidates for implantable cardioverter defibrillators. Clinical Trial Registration: URL: https://www.clinicaltrials.gov . Unique identifier: NCT03058185.

International audience; The water-processable microfibrillated cellulose (MFC) and sodium lignosulfonate (NaLS) system was used for the first time as carbon precursor. After drying and one-step pyrolysis up to 800 °C, the resulting bio carbonaceous char can acquire considerable electrical conductivity and porosity, making it a promising electrode material in energy storage devices. The present work characterizes MFC and NaLS separately as well as in blends in terms of morphology (SEM), structure (FTIR) and thermal stability (TG–MS). DTG patterns illustrate that MFC degrades in a narrow temperature range but at high reaction rates, whereas NaLS reacts more steadily in a larger temperature range. The thermal degradation rate of a MFC/NaLS blend differs from an additive weighted thermal degradation rate of each component: MFC and NaLS. The presence of sodium in the blends induced catalytic effects and made MFC decomposition to shift toward lower temperatures. This observation could be kinetically interpreted as a decrease of the MFC thermal degradation activation energies in the composites. The kinetics of MFC/NaLS blends is investigated by both model-free and mode-based methods, with the latter providing more appropriate Arrhenius parameters that allow reproducing the experimental curves

International audience; The present study has revealed that torrefied coffee grounds (CG) derived from agriculture commodities can be used as bioreinforcing agent for biodegradable poly(butylene adipate-co-terephthalate) (PBAT) without requiring a compatibilizer. The optimum torrefaction operation was achieved in order to increase the hydrophobicity of CG. The raw CG was also used as a reference to assess the effect of the torrefaction operation. The structure and morphology of the composites were examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The effect of the addition of raw or torrefied CG on the melting temperature and crystallinity of PBAT biocomposites was analyzed by differential scanning calorimetry (DSC). A significant enhancement in the thermo-mechanical properties for PBAT/torrefied CG composites was observed compared to PBAT/CG composites. Moreover, the hydrophobicity of PBAT composites which was determined by water contact angle was improved when torrefied biomass was added. The thermal stability of the investigated samples was analyzed by thermogravimetric analysis (TGA) and a kinetic model was proposed to describe the thermal degradation of raw CG, torrefied CG, PBAT, and their filled composites. The obtained results for these solvent-free prepared biocomposites show that they can be potential candidates for food packaging applications.

International audience; In the present work, electrically conductive and mechanically resistant carbon structures were elaborated by 3D printing and subsequent pyrolysis using microfibrillated cellulose/lignosulfonate/cellulose powder (labeled as MFC/LS/CP) blends. The processability of MFC/LS/CP slurries by 3D printing was examined by rheological tests in both steady flow and thixotropic modes. The printed MFC/LS/CP pastes were self-standing, provided a high printing definition and were proved to be morphologically stable to air drying and the subsequent pyrolysis. Pyrolysis at a slow rate (0.2 °C/min) to a final temperature ranging between 400 and 1200 °C was used to manufacture MFC/LS/CP carbons. The TGA/DTG was applied to monitor the thermal degradation of MFC/LS/CP materials in blends as well as in a separated form. The resulting carbons were further characterized in terms of morphology, microstructure and physical properties (such as density, electrical conductivity and mechanical strength). At 900 °C, MFC/LS/CP carbons displayed a high electrical conductivity of 47.8 S/cm together with a low density of 0.74 g/cm3 and a porosity of 0.58. They also achieved an elastic modulus of 6.62 GPa. Such interesting electrical and mechanical properties would lead to a promising application of MFC/LS/CP-derived biocarbons in energy storage devices as electrode materials in close future.

Nanocomposites are an opportunity to increase the performance of polymer membranes by fine-tuning their morphology. In particular, the understanding of the contribution of the polymer matrix/nanofiller interface to the overall transport properties is key to design membranes with tailored selective and adsorptive properties. In that aim, cellulose nanocrystals (CNC)/polylactide (PLA) nanocomposites were fabricated with chemically designed interfaces, which were ensuring the compatibility between the constituents and impacting the mass transport mechanism. A detailed analysis of the mass transport behaviour of different permeants in CNC/PLA nanocomposites was carried out as a function of their chemical affinity to grafted CNC surfaces. Penetrants (O2 and cyclohexane), which were found to slightly interact with the constituents of the nanocomposites, provided information on the small tortuosity effect of CNC on diffusive mass transport. The mass transport of water (highly interacting with CNC) and anisole (interacting only with designed CNC surfaces) exhibited non-Fickian, Case II behaviour. The water vapour caused significant swelling of the CNC, which created a preferential pathway for mass transport. CNC surface grafting could attenuate this phenomenon and decrease the water transport rate. Anisole, an aromatic organic vapour, became reversibly trapped at the specifically designed CNC/PLA interface, but without any swelling or creation of an accelerated pathway. This caused the decrease of the overall mass transport rate. The latter finding could open a way to the creation of materials with specifically designed barrier properties by designing nanocomposites interfaces with specific interactions towards permeants.

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This study takes place in a context of development of paper-based barrier packaging materials, using of microfibrillated cellulose (MFC) that brings renewability, recyclability, and biodegradability. Two strategies have been investigated: the wet lamination of a MFC barrier layer on board, and the use of MFC as additive in a water-based barrier coating colour. The promising use of MFC for the formation of barrier layers has been demonstrated in both cases. The wet lamination of MFC on board led to good oxygen and grease barrier properties, using highly fibrillated MFC. The board-MFC complex presented a strong adhesion after drying, without requiring glue. In the case of barrier coating, in order to obtain a low viscosity suspensions leading to high barrier layers, the use of highly fibrillated MFC mixed with a fully-hydrolysed poly(vinyl alcohol (PVOH) of low degree of polymerisation has been preferred. The addition of MFC in PVOH demonstrated its potential for improving the drying behaviour of water-barrier barrier coating colours. The combined use of MFC and layered silicates evidenced a synergistic effect on their dispersion in a PVOH solution, leading to an improved water vapour barrier while avoiding the formation of aggregates that otherwise damage the oxygen barrier. The work contributed to demonstrate the potential of MFC to be used for the formation of barrier layers, paving the way for the development of more sustainable barrier packaging materials., Ce travail se situe dans un contexte de développement de matériaux barrières pour l'emballage alimentaire papier-carton utilisant des microfibrilles de cellulose (MFC), ce qui donne une dimension renouvelable, recyclable, et biodégradable. Pour cela, deux stratégies ont été étudiées : l'utilisation des MFC pour la formation d'une couche barrière laminée à l'état humide sur carton, et en tant qu'additif dans une sauce de couchage barrière base aqueuse. Il a été montré que l'utilisation des MFC pour la production de couches barrières est prometteuse dans les deux cas. La lamination de MFC sur carton a permis d'obtenir de bonnes propriétés barrières à l'oxygène et à la graisse en utilisant des MFC hautement fibrillées. L'association carton-MFC a présenté une forte adhésion après séchage, permettant d'éviter l'utilisation de colle. Dans le cas du couchage composite, en vue de diminuer la viscosité et améliorer la barrière, il a été trouvé préférable d'utiliser un faible taux de MFC dans un alcool polyvinylique (PVOH) complètement hydrolysé ayant un faible degré de polymérisation. L'ajout de MFC dans une sauce de couchage composite a montré leur capacité à améliorer la cinétique de séchage du PVOH. L’utilisation combinée de MFC et de charges lamellaires a présenté un effet de synergie sur leurs états de dispersions dans une solution de PVOH, permettant leur utilisation pour l'amélioration de la barrière à la vapeur d'eau en conditions humides, tout en évitant la formation d'agrégats qui détérioreraient la barrière à l'oxygène. Ce travail a contribué à démontrer le potentiel des MFC pour la formation de couches barrières, ouvrant la voie au développement de nouveaux matériaux d'emballages plus responsables.

International audience; Lignocellulosic materials from municipal solid waste emerge as attractive resources for anaerobic digestion biorefinery.To increase the knowledge required for establishing efficient bioprocesses, dynamics of batch fermentation by the cellulolytic bacterium Ruminiclostridium cellulolyticum were compared using three cellulosic materials, paper handkerchief, cotton discs and Whatman filter paper. Fermentation of paper handkerchief occurred the fastest and resulted in a specific metabolic profile: it resulted in the lowest acetate-to-lactate and acetate-to-ethanol ratios. By shotgun proteomic analyses of paper handkerchief and Whatman paper incubations, 151 proteins with significantly different levels were detected, including 20 of the 65 cellulosomal components, 8 non-cellulosomal CAZymes and 44 distinct extracytoplasmic proteins. Consistent with the specific metabolic profile observed, many enzymes from the central carbon catabolic pathways had higher levels in paper handkerchief incubations. Among the quantified CAZymes and cellulosomal components, 10 endoglucanases mainly from the GH9 families and 7 other cellulosomal subunits had lower levels in paper handkerchief incubations. An in-depth characterization of the materials used showed that the lower levels of endoglucanases in paper handkerchief incubations could hypothetically result from its lower crystallinity index (50%) and degree of polymerization (970). By contrast, the higher hemicellulose rate in paper handkerchief (13.87%) did not result in the enhanced expression of enzyme with xylanase as primary activity, including enzymes from the ªxyl-docº cluster. It suggests the absence, in this material, of molecular structures that specifically lead to xylanase induction. The integrated approach developed in this work shows that subtle differences among cellulosic materials regarding chemical and structural characteristics have significant effects on expressed bacterial functions, in particular the cellulolysis machinery, resulting in different metabolic patterns and degradation dynamics.

International audience; Lignocellulosic materials from municipal solid waste emerge as attractive resources for anaerobic digestion biorefinery.To increase the knowledge required for establishing efficient bioprocesses, dynamics of batch fermentation by the cellulolytic bacterium Ruminiclostridium cellulolyticum were compared using three cellulosic materials, paper handkerchief, cotton discs and Whatman filter paper. Fermentation of paper handkerchief occurred the fastest and resulted in a specific metabolic profile: it resulted in the lowest acetate-to-lactate and acetate-to-ethanol ratios. By shotgun proteomic analyses of paper handkerchief and Whatman paper incubations, 151 proteins with significantly different levels were detected, including 20 of the 65 cellulosomal components, 8 non-cellulosomal CAZymes and 44 distinct extracytoplasmic proteins. Consistent with the specific metabolic profile observed, many enzymes from the central carbon catabolic pathways had higher levels in paper handkerchief incubations. Among the quantified CAZymes and cellulosomal components, 10 endoglucanases mainly from the GH9 families and 7 other cellulosomal subunits had lower levels in paper handkerchief incubations. An in-depth characterization of the materials used showed that the lower levels of endoglucanases in paper handkerchief incubations could hypothetically result from its lower crystallinity index (50%) and degree of polymerization (970). By contrast, the higher hemicellulose rate in paper handkerchief (13.87%) did not result in the enhanced expression of enzyme with xylanase as primary activity, including enzymes from the ªxyl-docº cluster. It suggests the absence, in this material, of molecular structures that specifically lead to xylanase induction. The integrated approach developed in this work shows that subtle differences among cellulosic materials regarding chemical and structural characteristics have significant effects on expressed bacterial functions, in particular the cellulolysis machinery, resulting in different metabolic patterns and degradation dynamics.

International audience; Capillary flows are increasingly used in biotechnology, biology, chemistry, energy and space applications. Motivated by these new developments, designs of capillary channels have become more sophisticated. In particular, capillary microsystems often use winding channels for reasons such as compactness, or mixing. The behavior of capillary microflows in curved channels is still underdeveloped. In this work, we investigate this type of behavior. In the case of suspended capillary flows, is shown that the flow profile in the curved section is approximately analogous to that in a rectilinear section. In the case of open U-grooves where inner corners are present, the importance of the turn sharpness and of the presence of capillary filaments is pointed out. For sharp turns, and/or in the presence of precursor capillary filaments, we found the phenomenon that the inner filament precedes the outer filament in the channel. Analysis of the capillary flow in curved channels is performed experimentally using rectangular U-grooves and suspended channels. The experimental observations are compared to Surface Evolver numerical software results.

International audience; The fox tapeworm Echinococcus multilocularis is the causative agent of alveolar echinococcosis, a severe zoonotic disease that may be fatal if untreated. A broad spectrum of mammalian species may be accidentally infected even in captivity. In April 2011, liver lesions due to E. multilocularis were observed during the necropsy of a captive-born nutria (Myocastor coypus) in a French wildlife park, leading to initiation of a study to survey the parasite's presence in the park. A comparable environmental contamination with fox's feces infected by E. multilocularis was reported inside (17.8%) and outside (20.6%) the park. E. multilocularis worms were found in the intestines of three of the five roaming foxes shot in the park. Coprological analyses of potential definitive hosts in captivity (fox, lynx, wildcat, genet, wolf, bear and raccoon) revealed infection in one Eurasian wolf. Voles trapped inside the park also had a high prevalence of 5.3%. After diagnosis of alveolar echinococcosis in a Lemur catta during necropsy, four other cases in L. catta were detected by a combination of ultrasound and serology. These animals were treated twice daily with albendazole. The systematic massive metacestode development and numerous protoscoleces in L. catta confirmed their particular sensitivity to E. multilocularis infection. The autochthonous origin of the infection in all the captive animals infected was genetically confirmed by EmsB microsatellite analysis. Preventive measures were implemented to avoid the presence of roaming foxes, contact with potential definitive hosts and contaminated food sources for potential intermediate hosts.

Cellulose nanofibrils (NFCs) are slender nanoparticles with outstanding mechanical properties that are used to enhance the mechanical properties of polymer nanocomposites and to fabricate dense and transparent nanopapers. However, the reinforcing effect of these nanoparticles is not as efficient for the elastic properties as expected from the classical models for polymer composites or fibrous materials. In this study, nanocomposite films made of TEMPO-oxidized NFCs and polyethylene oxide (PEO) were prepared by varying the NFC content over a wide range. The structural properties of these materials were characterized using AFM, TEM, SEM-FEG and XRD. These techniques showed that NFC nanocomposite films and nanopapers consisted of dense networks of tortuous NFCs with planar and random orientations. DMA experiments also revealed that the cohesive bonds between NFCs greatly contributed to the overall elastic response of these nanocomposites, even for low NFC contents. Based on these observations, we report an original multiscale network model that describes the elastic properties of NFC nanocomposites and nanopapers where the governing deformation mechanisms occurred at the numerous bonds between NFCs and in the NFC kinked regions, whereas the crystalline NFC regions were considered to be rigid bodies. This approach led to the formulation of an analytical expression for the stiffness tensors of NFC nanocomposites and nanopapers and revealed the effects of the network structure on their mechanical responses. The model predictions were satisfactory over the range of investigated NFC contents. In particular, this model showed the predominant role of the amorphous regions on the elastic response, whereas the contribution of the NFC–NFC bonds became significant at high NFC contents.

In the aim of producing fully organic bionanocomposite based on poly(lactide) (PLA), cellulose nanowhiskers (CNW) were grafted by n-octadecyl-isocyanate (CNW-ICN) applying an in situ surface grafting method. The compatibilizing effect of the long aliphatic grafted chain was investigated by thermal, mechanical and permeability analysis of solvent cast nanocomposite films. The grafted CNW-ICN could be successfully dispersed in the polymer matrix. The gained compatibility brought about a nucleating effect, decreasing the half time of isothermal crystallization from 25 min for the neat PLA to 8.4 min for the nanocomposite including 2.5 wt% CNW-ICN, e.g., tensile strength was improved by 10 MPa for the same 2.5 wt% CNW-ICN/PLA composite. Mechanical reinforcement was also effective in the rubbery state of PLA and increased the tensile modulus of the rubbery plateau providing thereby thermal resistance to the polymer. Oxygen barrier properties did not change significantly upon the inclusion of CNW-ICN, even when the quantity of CNW-ICN was increased to 15 wt%. More interestingly, the water vapour permeability of the CNW-ICN nanocomposite was always lower than the one of ungrafted CNW composites, which led to the conclusion that the hydrophobic surface graft and improved compatibility could counteract the effect of inclusion of hydrophilic structures in the matrix on water vapour transport. In conclusion, the surface grafting of CNW with isocyanates might be an easy and versatile tool for designing fully organic bionanocomposites with tailored properties.

International audience; In the aim of producing fully organic bionanocomposite based on poly(lactide) (PLA), cellulose nanowhiskers (CNW) were grafted by n-octadecyl-isocyanate (CNW-ICN) applying an in situ surface grafting method. The compatibilizing effect of the long aliphatic grafted chain was investigated by thermal, mechanical and permeability analysis of solvent cast nanocomposite films. The grafted CNW-ICN could be successfully dispersed in the polymer matrix. The gained compatibility brought about a nucleating effect, decreasing the half time of isothermal crystallization from 25 min for the neat PLA to 8.4 min for the nanocomposite including 2.5 wt% CNW-ICN, e.g., tensile strength was improved by 10 MPa for the same 2.5 wt% CNW-ICN/PLA composite. Mechanical reinforcement was also effective in the rubbery state of PLA and increased the tensile modulus of the rubbery plateau providing thereby thermal resistance to the polymer. Oxygen barrier properties did not change significantly upon the inclusion of CNW-ICN, even when the quantity of CNW-ICN was increased to 15 wt%. More interestingly, the water vapour permeability of the CNW-ICN nanocomposite was always lower than the one of ungrafted CNW composites, which led to the conclusion that the hydrophobic surface graft and improved compatibility could counteract the effect of inclusion of hydrophilic structures in the matrix on water vapour transport. In conclusion, the surface grafting of CNW with isocyanates might be an easy and versatile tool for designing fully organic bionanocomposites with tailored properties.

International audience; The ohmic curing of two silver micro-particle inks was studied. Silver lines of 35 to 75 µm thick were printed on a mixture of polycarbonate and acrylonitrile butadiene styrene (PC+ABS) substrate and on a mineral reinforced Nylon 6 thermoplastic, using a laboratory-made system based on a volumetric dosing dispenser. After 48 h of stabilization in ambient conditions, a current is applied through the printed lines with an imposed intensity value and application time in order to cure the silver inks. Evolutions of the temperature and the resistivity of silver tracks were followed during the process. Printed thermoplastics were characterized at the end of the process in order to check the absence of deformation due to the curing treatment. The study showed that the ohmic curing led to better electrical performances than an oven process with a considerable time saving. Most of the printed line resistivity drop occurred in the first 30 s of the treatment. The ohmic curing induced a local increase of temperature located in the printed line and avoided damaging the substrates, which makes the process compatible with thermal sensitive substrates. Therefore, the ohmic curing is an efficient low-cost process to cure silver micro-particle inks that could be easily implemented at an industrial scale.

International audience; Today’s environmental concerns are pressuring industries to substitute paper-based materials in place of plastics in many sectors including packaging. However, assembling papers and paperboards using environmentally friendly solutions remains a technological challenge. In this context, ultrasonic (US) welding is an alternative to adhesives. In this work, the potential of US welding to assemble folding boxboards was investigated. Folding boxboards are commonly coated to enhance printability. This coating is generally composed of mineral pigments (85 to 90%) and polymer binders (10 to 12%). This study evaluated whether the presence of the coating layer allows the assembly of paperboards by US welding. Results indicated that welding coated folding boxboards is possible provided that coating weight and binder content are high enough. The mechanical performances of the welded boards met the requirements of most packaging applications. Adhesion in the welded joint resulted from a combination of thermoplastic (melting and flowing of the binder) and thermoset (degradation reactions) effects. However, it was not possible to assemble coated folding boxboards without degrading the welding zone. While the materials and process need to be optimized, this work represents a big step forward toward the adhesive-free assembling of paper-based materials.

International audience; Fully-substituted cellulose esters with acyl substituents ranging in size from C2 to C18 were synthesized using the acyl chloride method. Films were prepared from the purified esters by either solvent-casting or compression-molding at elevated temperatures. Oxygen and water vapor permeability was determined under different conditions of pressure and moisture. The relationship between cellulose ester structure and barrier properties was examined. The results revealed linear relationships between water vapor and oxygen permeabilities and molar ester substituent volume as well as several structural factors relating to polymer polarity and hydrophobicity, such as aliphatic (methylene) content, solubility parameter, and contact angle. Films from long chain cellulose esters (LCCE) with acyl substituents in the size range between C8 and C18 were found to represent effective barriers to water vapor transport while their obstruction to the transfer of oxygen remained low. It was concluded that the hydrophobic nature of LCCEs is responsible for the control of water vapor transport, and that spatial factors dominate the transfer of oxygen.

Characterizing the mechanical properties of polymer coatings typically requires access to specialty equipment, the analysis through which can be tedious despite instrumental precision. An alternative method reported in the literature, strain-induced elastic buckling instability for mechanical measurements (SIEBIMM), is a high throughput, facile yet accurate method, used to characterize the Young’s modulus of supported films and coatings. SIEBIMM can easily be implemented in both academic and industrial settings. Hypothesis: We hypothesize that the SIEBIMM method has an upper coating thickness limit beyond which the assumptions and practicality of the method are no longer valid. Experiments: The Young’s moduli of model polyvinyl alcohol coatings (on polydimethylsiloxane substrates) with thicknesses ranging from 67 nm to 40 µm were determined using the SIEBIMM method and the data were subjected to a rigorous statistical analysis. Findings: SIEBIMM could accurately characterize coatings up to 35 µm thick. The Young’s modulus of all coatings ≤ 35 µm was 1.6 ± 0.1 GPa at 50% RH, which agreed with free-standing polyvinyl alcohol films measured by traditional tensile testing. For the method to be used on thicker coatings, it is essential to consistently measure coating thickness and buckling wavelength at the same location to minimize potential error.

International audience; The rheological properties of a dispersion of cellulose nanocrystals (CNCs) in an aqueous solution of polyoxyethylene (PEO) have been investigated. A peculiar behavior is reported. Upon adding CNC, the viscosity of the suspension first decreases and then increases. Adsorption of PEO chains on the surface of the nanoparticles has been suspected. Freeze-drying of this PEO-adsorbed CNC dispersion was performed, and the ensuing lyophilizate was extruded with low density polyethylene. Compared to neat CNC-based nanocomposites, both improved dispersibility and thermal stability were observed. This simple and physical method constitutes an approach of choice for the melt processing of CNC-based nanocomposites with a hydrophobic polymeric matrix applicable at the industrial scale.

International audience; High barrier and mechanically resistant three-dimensional (3D) cellulosic objects were produced using cellulose nanofibrils (CNF) and the molded cellulose process. The main objective is to improve properties of objects made by molding conventional papermaking fibers such as egg box. This well-known process, currently used for the production of low-end cellulose packaging, was simulated using 3Dprinted polycarbonate porous molds, dewatering, and heat compression stages. CNF produced by twin screw extrusion, which possess good barrier properties and transparency, were used as the base material, and different methods were used to form the cellulosic mats. Different drying techniques were tested in order to produce a transparent object and minimize the shrinkage of CNF upon drying, that is, oven-drying, thermopressing, microwave-drying, freeze-drying, or a combination. CNF cellulosic mats were easily formed, but due to the important shrinkage of CNF, none of the mat formation or drying techniques yielded transparent and dimensionally stable 3D objects.; Des objets cellulosiques tridimensionnels (3D) avec hautes propriétés barrière et mécaniquement résistants ont été produits à l'aide de nanofibrilles de cellulose (CNF) et du procédé de moulage de la cellulose. L'objectif principal est d'améliorer les propriétés des objets fabriqués par moulage de fibres papetières classiques telles que la boîte à œufs. Ce procédé bien connu, actuellement utilisé pour la production d'emballages cellulosiques bas de gamme, a été simulé à l'aide de moules poreux en polycarbonate imprimés en 3D, d'étapes de déshydratation et de compression thermique. Le CNF produit par extrusion à double vis, qui possède de bonnes propriétés de barrière et de transparence, a été utilisé comme matériau de base, et différentes méthodes ont été utilisées pour former les matelas cellulosiques. Différentes techniques de séchage ont été testées afin de produire un objet transparent et de minimiser le rétrécissement du CNF lors du séchage, c'est-à-dire le séchage au four, le thermopressage, le séchage par micro-ondes, la lyophilisation ou une combinaison. Les matelas cellulosiques CNF se formaient facilement, mais en raison du rétrécissement important du CNF, aucune des techniques de formation ou de séchage du tapis n'a donné des objets 3D transparents et dimensionnellement stables.

β-Mannans are a heterogeneous group of polysaccharides with a common main chain of β-1,4-linked mannopyranoside residues. The cleavage of β-mannan chains is catalyzed by glycoside hydrolases called β-mannanases. In the CAZy database, β-mannanases are grouped by sequence similarity in families GH5, GH26, GH113 and GH134. Family GH113 has been under-explored so far with six enzymes characterized, all from the Firmicutes phylum. We undertook the functional characterization of 14 enzymes from a selection of 31 covering the diversity of the family GH113. Our observations suggest that GH113 is a family with specificity towards mannans, with variations in the product profiles and modes of action. We were able to assign mannanase and mannosidase activities to four out of the five clades of the family, increasing by 200% the number of characterized GH113 members, and expanding the toolbox for fine-tuning of mannooligosaccharides.

International audience

Islet-specific glucose-6-phosphatase (G6Pase) catalytic subunit-related protein (IGRP) is a homolog of the catalytic subunit of G6Pase, the enzyme that catalyzes the terminal step of the gluconeogenic pathway. Its catalytic activity, however, has not been defined. Since IGRP gene expression is restricted to islets, this suggests a possible role in the regulation of islet metabolism and, hence, insulin secretion induced by metabolites. We report here a comparative analysis of the human, mouse, and rat IGRP genes. These studies aimed to identify conserved sequences that may be critical for IGRP function and that specify its restricted tissue distribution. The single copy human IGRP gene has five exons of similar length and coding sequence to the mouse IGRP gene and is located on human chromosome 2q28-32 adjacent to the myosin heavy chain 1B gene. In contrast, the rat IGRP gene does not appear to encode a protein as a result of a series of deletions and insertions in the coding sequence. Moreover, rat IGRP mRNA, unlike mouse and human IGRP mRNA, is not expressed in islets or islet-derived cell lines, an observation that was traced by fusion gene analysis to a mutation of the TATA box motif in the mouse/human IGRP promoters to TGTA in the rat sequence. The results provide a framework for the further analysis of the molecular basis for the tissue-restricted expression of the IGRP gene and the identification of key amino acid sequences that determine its biological activity.

This paper presents an off-line programming approach for the automatic generation of trajectories and the printing program for a 6-axis robot in order to print accurate conductive paths on 3D objects using a silver microparticle solvent-based ink. The aim of this study was to develop a semi-predictive model in order to - Adapt the printing parameters of a 6-axis robot arm and a piezo jetting print head to the printing speed and substrate type. - Print 3D electronic circuits matching the targeted geometry and conductivity. For the jetting printing process, 2D patterns printed on substrates with different roughness and wettability were analysed as a function of the print head translation speed and jetting frequency which were used as base variables to develop correlations in order to predict line width, thickness and conductivity. The model was based on the assumption that the behaviour of a single drop impacting the printing substrate is close to that of a train of drops (i.e. lines). Thus, the diameter of individual drops on a specific substrate was used to account for support properties and jetting conditions. The study also proposes a methodology to tune the circuit morphology by adapting the jetting parameters as a function of the trajectory and the speed of the 6-axis robot. As a representative case study, a 3D circuit was printed on a disposable paper cup obtaining an excellent agreement between measured and predicted conductivity values.

International audience

Fine prediction of the elastic properties of paper materials can now be obtained using sophisticated fibre scale numerical approaches. However, there is still a need, in particular for low-density papers, for simple and compact analytical models that enable the elastic properties of these papers to be estimated from the knowledge of various structural information about their fibres and their fibrous networks. For that purpose, we pursued the analysis carried out in Marulier et al. (Cellulose 22:1517–1539, 2015. https://doi.org/10.1007/s10570-015-0610-6 ) with low-density papers that were fabricated with planar random and orientated fibrous microstructures and different fibre contents. The fibrous microstructures of these papers were imaged using X-ray synchrotron microtomography. The corresponding 3D images revealed highly connected fibrous networks with small fibre bond areas. Furthermore, the evolutions of their Young’s moduli were non-linear and evolved as power-laws with the fibre content. Current analytical models of the literature do not capture these trends. In light of these experimental data, we developed a fibre network model for the in-plane elasticity of papers in which the main deformation mechanisms of the micromechanical model is the shear of the numerous fibre bonds and their vicinity, whereas the fibre parts far from these zones were considered as rigid bodies. The stiffness tensor of papers was then estimated both numerically using a discrete element code and analytically using additional assumptions. Both approaches nicely fit the experimental trends by adjusting a unique unknown micromechanical parameter, which is the shear stiffness of bonding zones. The estimate of this parameter is relevant in light of several recently reported experimental results.

International audience; Ultrasonic welding is a serious candidate in the development of methods to assemble papers and paperboards without using additional substances. However, the ultrasonic welding of papers remains a technological challenge considering the low weldability of lignocellulosic materials. This study aims to investigate on the ultrasonic welding process applied to papers in order to identify the processing conditions which favor the formation of strong welded joints. To reach such purpose, an experimental strategy was developed by combining the characterization of welded materials and the monitoring of process parameters. Experimentations were performed using a reference paper displaying a good weldability to specifically highlight the contribution of process parameters. Results indicate that the process is highly sensitive to vibration amplitude, power supplied by the high frequency generator, and sample thickness. Power seems to be a reliable indicator of the severity of the process. A strong decrease in the strength of the welded joints is observed when working with low thicknesses. It seems that the layers coated on top of papers are the main part of the material contributing in the development of adhesion at the welding joint. Overall, instrumenting the device has led to a better understanding of the ultrasonic welding of papers.

Facing climate change and the near end of the oil age led us to rethink our consumption patterns and energy models, to insure a sustainable future four human beings. In this way, the biorefinery plays an important role and is a key concept to bring a part of the solution, exploiting the potential of biomass, which is renewable and widely available, for energy production and chemicals, materials, human health, and agri-food products manufacturing. Hence, this project aims at valorizing wood hemicelluloses in the frame of a lignocellulosic biorefinery integrated in a kraft pulp mill. These are complex heteropolysaccharides accounting of one third of wood and the second most abundant biopolymer on earth. Both softwood and hardwood chips industrial mixtures are used for hemicelluloses oligomers extraction prior to the kraft process through a low-tech and green process (without using any chemicals) named autohydrolysis. This pretreatment step allows for the solubilization of oligosaccharides, monosaccharides, lignin fragments and other small molecular weight organic compounds and is the only one used at an industrial scale to produce hemicelluloses from wood. The chemical composition of these wood hydrolysates depends much on wood species and autohydrolysis severity. The main objective of the thesis is to design a sort of universal scheme of analytical methods that can be applied to any kind of hydrolysate in order to identify, quantify and isolate its hemicelluloses families.The study of the molecular diversity of soluble oligosaccharides containing liquors produced at high and low temperature (150 and 170°C) is based on several purifications’ steps before analysis. First of all, membrane filtration is used with different molecular weight cut-offs to classify and separate oligomers from impurities according to their size. In a second part, soluble lignin and sugar degradation products generated during autohydrolysis are removed by adsorption on activated charcoal. Less polydisperse and 99% pure oligosaccharides mixtures are thus obtained thanks to the optimization and combination of these two techniques of purification. Nevertheless, big losses of hemicelluloses are triggered by these treatments between 70 and 80% compared to the raw hydrolysate. In the end, the last chapter of experiments deals with the final purification and characterization steps of these purified samples which are performed by size exclusion liquid chromatography and mass spectrometry analyses. This chromatographic technique operating at low pressure is an interesting tool for the separation of neutral oligomers from hexuronic acid substituted oligomers in both hardwood and softwood extracts produced at high temperature. Also, elimination of recalcitrant lignin carbohydrates complexes was achieved for some fractions as well as the isolation of specific bioactive molecules of low degree of polymerization (potential nutraceutical applications).Key words : Biorefinery, Hemicelluloses, Soluble Oligosaccharides, Wood Chemistry, Analytical Chemistry, Activated Charcoal, Ultrafiltration, GFC, MALDI-TOF MS, GC-FID, HPAEC-PAD, La définition de nouveaux modes de consommation et la fin progressive de l’ère pétrolière s’imposent à nous comme piliers pour assurer un avenir soutenable aux générations futures. C’est dans ce sens que la bioraffinerie au sens large a un rôle majeur à jouer aujourd’hui et qu’elle a été désignée comme concept clé d’exploitation durable d’une ressource renouvelable qu’est la biomasse végétale pour la production d’énergie, de matériaux et de produits chimiques, mais aussi de produits pour l’alimentation animale et la santé humaine. Dans ce contexte, cette thèse vise à valoriser les hémicelluloses du bois dans le cadre d’une bioraffinerie lignocellulosique intégrée à la production de fibres de cellulose. Ces hétéropolysaccharides complexes représentent 30% du bois et sont les deuxièmes biopolymères les plus abondants sur terre. Dans ce projet, ils sont donc extraits par solubilisation en amont du procédé papetier par un prétraitement nommé autohydrolyse. Ce traitement relativement propre car consommant peu d’énergie et n’utilisant aucun produit chimique, est choisi pour la production d’hémicelluloses à partir de mélanges de copeaux de bois industriels de feuillus et de résineux. Il s’agit du seul moyen de production d’hémicelluloses issue du bois déjà utilisé à échelle industrielle. La caractérisation des hydrolysats résultants est complexe car ils contiennent des composés de nature chimique très différente dont la composition varie grandement avec l’essence de bois et la sévérité du traitement. Le principal objectif de cette thèse est de définir un schéma de méthodes analytiques applicable et adaptable à tout type d’hydrolysat, afin d’en isoler et cartographier les familles d’hémicelluloses.L’étude de la diversité moléculaire des oligosaccharides solubles contenus dans ces autohydrolysats de bois, produits à basse et haute température (150 et 170°C), passe par plusieurs étapes de purification et d’analyse. D’abord les oligomères sont classés et séparés des impuretés en fonction de leur taille grâce à l’emploi de l’ultrafiltration membranaire. Puis la lignine et les produits de dégradation des sucres formés lors de l’autoprotolyse sont éliminés des hydrolysats par adsorption sur des grains de charbon actif. L’optimisation et la combinaison de ces deux techniques de purification adaptées à l’essence de bois et la température d’extraction utilisées permettent ainsi d’obtenir des mélanges d’oligosaccharides moins polydispersés que l’hydrolysat de départ et purs en oligosaccharides d’hémicelluloses à 99%. Cependant ces traitement engendrent des pertes en oligosaccharides, de l’ordre de 70 à 80% en masse sèche par rapport à l’hydrolysat de départ. Elles sont dues à l’adsorption sur le charbon actif ou au passage à travers les pores des membranes de filtration. Ces mélanges sont donc plus aptes à être fractionnés par chromatographie liquide d’exclusion stérique et analysés par spectrométrie de masse. Il s’agit de la dernière partie expérimentale de cette étude. La chromatographie d’exclusion stérique a notamment permis la quantification et la séparation entre oligomères chargés d’acides hexuroniques et oligomères neutres à la fois des hydrolysats de feuillus et de résineux produits à haute température. Pour certaines fractions l’élimination des complexes lignine hydrates de carbone récalcitrant à l’adsorption au charbon actif a pu être réalisée ainsi que l’isolation de certaines molécules bioactives de faible degré de polymérisation (valorisables en produits nutraceutiques).Mots clés : Bioraffinerie, Autohydrolyse, Hémicelluloses, Oligosaccharides Solubles, Chimie du Bois, Chimie Analytique, Charbon Actif, Ultrafiltration, GFC, MALDI-TOF MS, GC-FID, HPAEC-PAD

Cellulose nanofibrils (CNF) are renewable bio-based materials with high specific area, which makes them ideal candidates for multiple emerging applications including for instance on-demand drug release. However, in-depth chemical and structural characterization of the CNF surface chemistry is still an open challenge, especially for low weight percentage of functionalization. This currently prevents the development of efficient, cost-effective and reproducible green synthetic routes and thus the widespread development of targeted and responsive drug-delivery CNF carriers. We show in this work how we use dynamic nuclear polarization (DNP) to overcome the sensitivity limitation of conventional solid-state NMR and gain insight into the surface chemistry of drug-functionalized TEMPO-oxidized cellulose nanofibrils. The DNP enhanced-NMR data can report unambiguously on the presence of trace amounts of TEMPO moieties and depolymerized cellulosic units in the starting material, as well as coupling agents on the CNFs surface (used in the heterogeneous reaction). This enables a precise estimation of the drug loading while differentiating adsorption from covalent bonding (∼1 wt% in our case) as opposed to other analytical techniques such as elemental analysis and conductometric titration that can neither detect the presence of coupling agents, nor differentiate unambiguously between adsorption and grafting. The approach, which does not rely on the use of 13C/15N enriched compounds, will be key to further develop efficient surface chemistry routes and has direct implication for the development of drug delivery applications both in terms of safety and dosage., DNP-enhanced solid-state NMR unravels the surface chemistry of functionalized nanocellulose.

The breakdown and buildup mechanisms in concentrated cellulose nanocrystal (CNC) suspensions under shear and during relaxation upon cessation of shear were accessed by small-angle X-ray and light scattering combined with rheometry. The dynamic structural changes over nanometer to micrometer lengthscales were related to the well-known three-regime rheological behavior. In the shear-thinning regime I, the large liquid crystalline domains were progressively fragmented into micrometer-sized tactoids, with their cholesteric axis aligned perpendicular to the flow direction. The viscosity plateau of regime II was associated to a further disruption into submicrometer-sized elongated tactoids oriented along the velocity direction. At high shear rate, regime III corresponded to the parallel flow of individual CNCs along the velocity direction. Upon cessation of flow, the relaxation process occurred through a three-step buildup mechanisms: i) a fast reassembling of the individual CNCs into a nematic-like organization established up to micrometer lengthscales, ii) a slower formation of oriented large cholesteric domains, and iii) their isotropic redistribution.

International audience; Several naturally occurring biological systems, such as bones, nacre or wood, display hierarchical architectures with a central role of the nanostructuration that allows reaching amazing properties such as high strength and toughness. Developing such architectures in man-made materials is highly challenging, and recent research relies on this concept of hierarchical structures to design high-performance composite materials. This review deals more specifically with the development of hierarchical fibres by the deposition of nano-objects at their surface to tailor the fibre/matrix interphase in (bio)composites. Fully synthetic hierarchical fibre reinforced composites are described, and the potential of hierarchical fibres is discussed for the development of sustainable biocomposite materials with enhanced structural performance. Based on various surface, microstructural and mechanical characterizations, this review highlights that nano-objects coated on natural fibres (carbon nanotubes, ZnO nanowires, nanocelluloses) can improve the load transfer and interfacial adhesion between the matrix and the fibres, and the resulting mechanical performances of biocomposites. Indeed, the surface topography of the fibres is modified with higher roughness and specific surface area, implying increased mechanical interlocking with the matrix. As a result, the interfacial shear strength (IFSS) between fibres and polymer matrices is enhanced, and failure mechanisms can be modified with a crack propagation occurring through a zig-zag path along interphases.

The objective of this thesis is the development of a 6-axis robotic cell allowing the printing of electronic circuits on the surface of freeform objects and adapted to the prototyping and small series production of 3D objects integrating surface electronics.The manufacturing method proposed, from design to printing with a phase of scanning, mesh construction, circuit projection and speed analysis, is very useful for prototyping and small series applications where it is necessary to frequently change the substrate and the dimensions of the 3D object.An off-line programming approach allowing the printing of conductive trajectories on 3D objects and the automatic generation of the trajectory and the printing robot program has been developed. And a methodology to predict the circuit morphology by adapting the projection parameters according to the trajectory and the speed of the 6-axis robot has been proposed.A dedicated interface to manage the complete process has also been developed to control the printing process making it possible for people who are not experts in robotics to use the cell because its use does not require programming, the programs being generated automatically.Finally, prototypes were presented.; L’objectif de cette thèse est le développement d'une cellule robotisée 6 axes permettant l'impression de circuits électroniques à la surface d'objets de forme quelconque et adaptée au prototypage et à la production en petite série d'objets 3D intégrant de l'électronique de surface.La méthode de fabrication proposée se divise en plusieurs phases : une phase de numérisation, une phase de construction du maillage, une phase de projection de circuits, une phase d'analyse de la vitesse et une phase d’impression. Ce processus est flexible et très utile pour les applications de prototypage et de petites séries pour lesquelles il est nécessaire de changer fréquemment le substrat et les dimensions de l'objet 3D.Une approche de programmation hors ligne permettant l'impression de trajectoires conductrices sur des objets 3D et la génération automatique de la trajectoire et du programme robot d'impression a été développée. Et une méthodologie pour prédire la morphologie du circuit en adaptant les paramètres de projection en fonction de la trajectoire et de la vitesse du robot 6 axes a été proposée.Une interface dédiée qui permet de gérer le processus complet a également été développée pour gérer le processus d'impression rendant ainsi possible l'utilisation de la cellule par des personnes qui ne sont pas des experts en robotique car son utilisation ne nécessite pas de programmation, les programmes étant générés automatiquement.Enfin, des prototypes ont été présentés.

The objective of this thesis is the development of a 6-axis robotic cell allowing the printing of electronic circuits on the surface of freeform objects and adapted to the prototyping and small series production of 3D objects integrating surface electronics.The manufacturing method proposed, from design to printing with a phase of scanning, mesh construction, circuit projection and speed analysis, is very useful for prototyping and small series applications where it is necessary to frequently change the substrate and the dimensions of the 3D object.An off-line programming approach allowing the printing of conductive trajectories on 3D objects and the automatic generation of the trajectory and the printing robot program has been developed. And a methodology to predict the circuit morphology by adapting the projection parameters according to the trajectory and the speed of the 6-axis robot has been proposed.A dedicated interface to manage the complete process has also been developed to control the printing process making it possible for people who are not experts in robotics to use the cell because its use does not require programming, the programs being generated automatically.Finally, prototypes were presented., L’objectif de cette thèse est le développement d'une cellule robotisée 6 axes permettant l'impression de circuits électroniques à la surface d'objets de forme quelconque et adaptée au prototypage et à la production en petite série d'objets 3D intégrant de l'électronique de surface.La méthode de fabrication proposée se divise en plusieurs phases : une phase de numérisation, une phase de construction du maillage, une phase de projection de circuits, une phase d'analyse de la vitesse et une phase d’impression. Ce processus est flexible et très utile pour les applications de prototypage et de petites séries pour lesquelles il est nécessaire de changer fréquemment le substrat et les dimensions de l'objet 3D.Une approche de programmation hors ligne permettant l'impression de trajectoires conductrices sur des objets 3D et la génération automatique de la trajectoire et du programme robot d'impression a été développée. Et une méthodologie pour prédire la morphologie du circuit en adaptant les paramètres de projection en fonction de la trajectoire et de la vitesse du robot 6 axes a été proposée.Une interface dédiée qui permet de gérer le processus complet a également été développée pour gérer le processus d'impression rendant ainsi possible l'utilisation de la cellule par des personnes qui ne sont pas des experts en robotique car son utilisation ne nécessite pas de programmation, les programmes étant générés automatiquement.Enfin, des prototypes ont été présentés.

International audience; Biomass composition on cellulose, hemicelluloses and lignin determinates its behavior in torrefaction (200–350 °C, default-oxygen atmosphere). Up to now, commercial microcrystalline cellulose was typically used to represent cellulose behavior in biomass torrefaction models based on macromolecular components. The objective of this work is to evaluate the impact of cellulose properties on its behavior in torrefaction, so as to identify the most suitable cellulose sample for modelling. To do this, five extracted celluloses from woody and agricultural biomass, commercial microcrystalline cellulose (Avicel) and four cotton linters tailored to different degrees of polymerization (DP) were considered. Cellulosic samples were deeply characterized in terms of fiber analysis, molar mass distribution (MMD), hydrodynamic behavior (SEC-RALS) and allomorphic structure. Cellulosic samples were torrefied in a thermogravimetric analysis up to two temperatures, leading to partial (300 °C) and total (350 °C) cellulose degradation. Extracted celluloses and Avicel cellulose degradation profiles showed strong differences at 300 °C. Polymer MMD, dispersity and the presence of residual hemicellulose sugars, especially xylose, strongly impacted cellulose degradation through torrefaction. Extracted celluloses presented high purity, narrow MMD and high DP, but a cellulose II structure due to mercerization. This cellulosic allomorph was shown to be more reactive, but it led to an identical final solid mass loss. The observed hydrodynamic behavior and the probable preservation of cellulose amorphous areas from native cellulose may also influence polymer structural behavior in torrefaction. Finally, at least one-order-of-magnitude DP variation was shown to be required to see an impact in cellulose degradation profile through torrefaction.

International audience; TEMPO-Oxidized cellulose nanofibrils (toCNF), in the form of highly entangled network such as membrane or cryogels, have proven to be of interest for various applications, including drug release or purification by pollutant adsorption. β-Cyclodextrins (β-CDs) have the ability to form inclusion complexes with large amount of hydrophobic molecules, and are considered as a promising way to bring new functionalities to these materials, by reducing drug burst release effect or improving the pollutant adsorption properties. The study of the adsorption β-CDs onto toCNF is then crucial to design toCNF/β-CDs materials, but is very complex due to the chemical proximity between these compounds. In this study, we develop toCNF cryogels containing various types of β-CDs derivatives by physical adsorption. Different protocols for analyzing the interactions between these compounds, such as Isothermal Titration Calorimetry (ITC), Quartz-Crystal Microbalance with dissipation monitoring (QCM-d) and a Phenolphthalein-based protocol (PhP protocol) have been performed. Adsorption between β-CD and toCNF was proven at two different temperatures with ITC. QCM-d measurements allowed measuring adsorption of different β-CDs derivatives onto toCNF, with higher adsorption measured for the modified β-CDs, and with estimated binding capacity ranging from 13.4 to 47.6 μmol/g toCNF. PhP protocol allowed us to monitor the amount of β-CDs released in aqueous environment, highlighting a lower release for modified β-CDs onto toCNF, and the results were consistent with the estimated binding capacity. This quantification of the binding adsorption capacity of various β-CDs is key results for optimizing the design of toCNF/β-CDs materials.

International audience; In this study, a new approach to optimize the cellulose nanocrystals (CNCs) extraction using acidic natural deep eutectic solvents (NADES) was introduced using, for the first time, design of experiment method. Choline chloride:oxalic acid dihydrate with a molar ratio of 1:1 was used to extract CNCs. Then, three most important parameters were varied to design the experiment: (i) cotton fibre concentrations, (ii) temperature and (iii) treatment time. Two outcomes were studied: the CNC yield and the crystallinity. The mathematical model for crystallinity perfectly described the experiments, while the model for CNC yield provided only a tendency. For a reaction time of 6 h at 95°C with a fibre concentration of 2%, the expected optimum CNC yield was approximately 35.5 ± 2.7% with a crystallinity index of 80 ± 1%. The obtained experimental results confirmed the models with 43.6 ± 1.9% and 81 ± 1% for the CNC yield and the crystallinity index, respectively. This study shows that it is possible to predict the CNC yield CNC and their crystallinity thanks to predictive mathematical models, which gives a great advantage to consider in the near future a scale up of the extraction of cellulose nanocrystals using this original family of green solvents.

International audience; This work is focused on the modification of the interphase zone in short flax fibres / polypropylene (PP) composites by a bio-inspired modification of fibres called “nanostructuration” that uses the adsorption of biomass by-products, i.e. cellulose nanocrystals (CNC) and xyloglucan (XG), to create hierarchical flax fibres. The wettability and interfacial adhesion study reveals a strong decrease in the polar character of CNC modified flax fibres, hence increasing the work of adhesion with PP. Moreover, combining XG/CNC modified interphases with MAPP coupling agent enhances the ultimate mechanical properties of biocomposites with higher tensile strength and work of rupture, and modifies failure mechanisms as revealed by in situ micro-mechanical tensile SEM experiments. Bio-based hierarchical composites inspired by naturally occurring nanostructures open a new path for the development of sustainable composites with enhanced structural properties.

International audience; Capillary-driven impregnation phenomena occurring in fibre bundles during the processing of composite materials are complex and still not fully understood. Hence, synchrotron X-ray microtomography was used to characterise the longitudinal propagation of the flow front within a parallel arrangement of rigid fibres. The analysis of 3D images enabled the fluid-air interface curvatures, triple line lengths, and local contact angles to be quantified during wetting and dewetting experiments. The results showed that even in quasi-static situations, local contact angles exhibited significant variations along the fibres. These variations also depended on the wetting/dewetting state. The transverse capillary forces measured at the fibre scale from the analysis of 3D images were shown to be of the same order of magnitude as the longitudinal capillary forces. Local curvatures of the fluid-air interface and the resulting estimate of the average capillary pressure proved the relevance of a mesoscale capillary pressure model adapted for fibre bundles.

This Ph.D. thesis covers the production and characterization of gelatin-cellulose nanocrystals (CNCs) bionanocomposite films intended for multifunctional food packaging. The up-scalability of the gelatin/CNCs films was attained by continuous casting and the rheological parameters of the film-forming solutions and drying temperature required to produce 12 m film/h were established. The continuous casting processing was proven to be advantageous when compared to the bench solution casting method. Tensile tests, thermogravimetric analysis, and water vapor permeability analysis showed that the continuously cast gelatin/CNCs films had exceptionally better performance than the films obtained by bench casting. The physical and structural properties of the gelatin/CNCs bionanocomposites as tailored by pH-dependent electrostatic interactions were investigated. The suitability of CNCs was successfully extended by functionalization with rosin (r-CNCs), thus giving rise to antimicrobial reinforcing agents. Tensile tests and antimicrobial analysis showed that r-CNCs served as bacterial nanofillers in gelatin-based films, which otherwise would suffer from limited physical and biological properties. Plant-derived tannic acid was successfully used as an antioxidant and bactericidal additive, as another perspective of extending the potential of the gelatin/CNCs films as a packaging material. Non-oxidized tannic acid favored non-covalent interactions and intermolecular connections between gelatin, CNCs, and tannic acid. These physico chemical interactions showed to have a greater influence on the antioxidant and physical properties of gelatin/CNCs/Tannic acid films. This thesis provides a comprehensive understanding of how CNCs can be explored to develop biodegradable films based on gelatin with enhanced properties or extra functionalities. A continuous solution casting was applied for scaling up the production of gelatin/CNCs-based films making them highly desirable for packaging applications., Cette thèse étudie la production et la caractérisation de films bionanocomposites de gélatine-cellulose nanocristaux (CNCs) destinés aux emballages alimentaires multifonctionnels. L’évolutivité des films de gélatine/CNCs a été obtenue par casting continu, et les paramètres rhéologiques des solutions filmogènes et la température de séchage nécessaire pour produire 12 m de film/h ont été établis. Le processus de casting continu s'est avéré avantageux par rapport au processus de casting conventionnel. Les tests de traction, l'analyse thermogravimétrique et l'analyse de perméabilité à la vapeur d'eau ont montré que les films de gélatine/CNCs laminés produits continuellement ont eu une meilleure performance que ceux obtenus par casting conventionnel. Les propriétés physiques et structurelles des gélatine/CNCs modulé par des interactions électrostatiques changés par le pH ont été étudiées. La fonction des CNCs a été étendue avec succès par la fonctionnalisation avec rosin (r-CNCs), qui a produit des nanocharges antimicrobiennes. Des tests de traction et des analyses antimicrobiennes ont montré que les r-CNCs servent d’agent antibactériens dans les films à base de gélatine. Sans cela, les films souffriraient autrement de propriétés physiques et biologiques limitées. L'acide tannique a été utilisé avec succès comme antioxydant et additif antibactérien, comme une autre perspective pour développer le potentiel des films de gélatine/CNCs comme matériel d'emballage. L'acide tannique non oxydé a favorisé les interactions non covalentes et intermoléculaires entre la gélatine, les CNCs et l'acide tannique. Ces interactions physico-chimiques ont montré une plus grande influence sur les propriétés antioxydantes et physiques des films gélatine/CNCs-acide tannique. Cette thèse donne une compréhension globale de la façon dont la CNCs peut être exploitée pour développer des films biodégradables à base de gélatine avec des propriétés améliorées ou des fonctionnalités supplémentaires. Le casting continu a été appliqué afin d’augmenter la production de films de gélatine/CNCs, ce que rend les films hautement souhaitables pour les applications d'emballage.

In line with the latest innovations in the packaging field, this joint project aims at implementing new and innovative micro- and nanoparticles for the development of active and intelligent packaging solutions dedicated to food and medical packaging applications. More specifically, the project combines two major developments which both falls within the scope of active and intelligent packaging. In this work, a specific focus was given to the development of an antibacterial packaging solution and to the development of smart gas sensors. The antibacterial strategy developed was based on the combination of two active materials - silver nanowires and cellulose nanofibrils - to prepare antibacterial surfaces. The formulation as an ink and the deposition processing has been deeply studied for different surface deposition processes that include coatings or screen-printing. Results showed surfaces that display strong antibacterial activity both against Gram-positive and Gram-negative bacteria, but also interesting properties for active packaging applications such as a highly retained transparency or enhanced barrier properties. Regarding the second strategy, gas sensors have been prepared using a combination of Copper benzene-1,3,5-tricarboxylate Metal Organic Framework and carbon-graphene materials, deposited on flexible screen-printed electrodes. The easy-to-produce and optimized sensors exhibit good performances toward ammonia and toward humidity sensing, proving the versatility and the great potential of such solution to be adapted for different target applications. The results of this project lead to innovative solutions that can meet the challenges raised by the packaging industry., En lien avec les dernières innovations dans le domaine des emballages, ce projet collaboratif a pour but d’implémenter de nouveaux micro- et nanomatériaux innovants pour le développement d’emballages actifs et intelligents dans le domaine alimentaire et médical. Il se focalise en particulier sur deux stratégies : le développement d’emballages antibactériens d’un côté et de capteurs de gaz de l’autre. La première stratégie est donc dédiée à l’utilisation combinée de nanofils d’argent et de nanofibrilles de cellulose pour la production de surfaces antibactériennes. La formulation d’encres ainsi que les paramètres de dépôt ont été optimisés pour différent procédés tels que l’enduction ou l’impression sérigraphique. Une forte activité antibactérienne contre des souches bactériennes Gram-positive mais aussi Gram-négative a été prouvée pour toutes les surfaces préparées. Des propriétés intéressantes relatives au domaine des emballage actifs ont aussi été démontrées telles que la conservation d’une haute transparence et l’amélioration des propriétés barrières. Dans la seconde stratégie, des capteurs de gaz ont été préparés en utilisant un mélange actif composé de Cuivre benzène-1,3,5-tricarboxylate Metal Organic Framework et de carbone-graphène, déposé sur des électrodes flexibles produites par sérigraphie. Les capteurs sont faciles à produire et ont été optimisés pour présenter de bonnes performances à la fois pour détecter et quantifier l’ammoniac gazeux mais aussi servir de capteurs d’humidité, ce qui prouve leur versatilité et leur important potentiel industriel. Ce projet a donc conduit à différentes solutions innovantes qui peuvent relever les défis de l’industrie des emballages.

In line with the latest innovations in the packaging field, this joint project aims at implementing new and innovative micro- and nanoparticles for the development of active and intelligent packaging solutions dedicated to food and medical packaging applications. More specifically, the project combines two major developments which both falls within the scope of active and intelligent packaging. In this work, a specific focus was given to the development of an antibacterial packaging solution and to the development of smart gas sensors. The antibacterial strategy developed was based on the combination of two active materials - silver nanowires and cellulose nanofibrils - to prepare antibacterial surfaces. The formulation as an ink and the deposition processing has been deeply studied for different surface deposition processes that include coatings or screen-printing. Results showed surfaces that display strong antibacterial activity both against Gram-positive and Gram-negative bacteria, but also interesting properties for active packaging applications such as a highly retained transparency or enhanced barrier properties. Regarding the second strategy, gas sensors have been prepared using a combination of Copper benzene-1,3,5-tricarboxylate Metal Organic Framework and carbon-graphene materials, deposited on flexible screen-printed electrodes. The easy-to-produce and optimized sensors exhibit good performances toward ammonia and toward humidity sensing, proving the versatility and the great potential of such solution to be adapted for different target applications. The results of this project lead to innovative solutions that can meet the challenges raised by the packaging industry.; En lien avec les dernières innovations dans le domaine des emballages, ce projet collaboratif a pour but d’implémenter de nouveaux micro- et nanomatériaux innovants pour le développement d’emballages actifs et intelligents dans le domaine alimentaire et médical. Il se focalise en particulier sur deux stratégies : le développement d’emballages antibactériens d’un côté et de capteurs de gaz de l’autre. La première stratégie est donc dédiée à l’utilisation combinée de nanofils d’argent et de nanofibrilles de cellulose pour la production de surfaces antibactériennes. La formulation d’encres ainsi que les paramètres de dépôt ont été optimisés pour différent procédés tels que l’enduction ou l’impression sérigraphique. Une forte activité antibactérienne contre des souches bactériennes Gram-positive mais aussi Gram-négative a été prouvée pour toutes les surfaces préparées. Des propriétés intéressantes relatives au domaine des emballage actifs ont aussi été démontrées telles que la conservation d’une haute transparence et l’amélioration des propriétés barrières. Dans la seconde stratégie, des capteurs de gaz ont été préparés en utilisant un mélange actif composé de Cuivre benzène-1,3,5-tricarboxylate Metal Organic Framework et de carbone-graphène, déposé sur des électrodes flexibles produites par sérigraphie. Les capteurs sont faciles à produire et ont été optimisés pour présenter de bonnes performances à la fois pour détecter et quantifier l’ammoniac gazeux mais aussi servir de capteurs d’humidité, ce qui prouve leur versatilité et leur important potentiel industriel. Ce projet a donc conduit à différentes solutions innovantes qui peuvent relever les défis de l’industrie des emballages.

International audience; In this work, we present an innovative strategy for the grafting of an antibacterial agent onto nanocellulose materials in supercritical carbon dioxide (scCO2). Dense cellulose nanofibril (CNF) nanopapers were prepared and subsequently functionalized in supercritical carbon dioxide with an aminosilane, N-(6-aminohexyl)aminopropyltrimethoxysilane (AHA-P-TMS). Surface characterization (X-ray photoelectron spectroscopy, contact angle, ζ-potential analysis) evidenced the presence of the aminosilane. The results show that the silane conformation depends on the curing process: a nonpolycondensed conformation of grafted silane with the amino groups facing outwards was favored by curing in an oven, while the curing step performed in scCO2 yielded CNF structures with the alkyl chain facing outwards. The grafted nanopapers exhibited antibacterial activity, and no antibacterial agent was released into the media. Furthermore, these materials proved to benefit from low cytotoxicity. This study offers a proof of concept for the covalent grafting of active species on nanocellulose structures and the control of aminosilane orientation using a green and controlled approach. These newly designed materials could be used for their antibacterial activity in the biomedical field. Thus, perspectives for topical administration and design of wound dressing could be envisaged.

We report on gelatin films incorporating rosin-grafted cellulose nanocrystals (r-CNCs), which fulfill the most relevant requirements for antimicrobial packaging applications. Transparent gelatin/r-CNCs bionanocomposite films (0.5–6 wt% r-CNCs) were obtained by solution casting and displayed high UV-barrier properties, which were superior to the most used plastic packaging films. The gelatin/r-CNCs films exhibited a moderate water vapor permeability (0.09 g mm/m2 h kPa), and high tensile strength (40 MPa) and Young's modulus (1.9 GPa). The r-CNCs were more efficient in improving the optical, water vapor barrier and tensile properties of gelatin films than conventional CNCs. Grafting of rosin on CNCs resulted in an antimicrobial nanocellulose that inhibited the growth of Staphylococcus aureus and Escherichia coli. The antibacterial properties of r-CNCs were sustained in the gelatin films, as demonstrated by agar diffusion tests and proof-of-principle experiments involving cheese storage. Overall, the incorporation of r-CNCs as active fillers in gelatin films is a suitable approach for producing novel eco-friendly, antimicrobial packaging materials., This research was made possible thanks to the facilities of the Laboratory of Pulp and Paper 479 Science and Graphic Arts (LGP2) that is part of the LabEx Tec 21 (Investissements d'Avenir - grant 480 agreement n°ANR-11-LABX-0030) and of PolyNat Carnot Institute (Investissements d'Avenir - 481 grant agreement n° ANR-16-CARN-0025- 0), and Plant Macromolecule Research Center 482 (CERMAV) for the support to this work. This study was financed in part by CNPq, SISNANO 26 483 (MCTI), FINEP, Embrapa AgroNano research network (Embrapa), Coordenação de 484 Aperfeiçoamento de Pessoal de Nível Superior - Brazil (CAPES) [Finance Code 001] and by the 485 São Paulo Research Foundation (FAPESP) [grant numbers 2016/03080-2, 2017/18725-2 and 486 2018/00278-2, 2018/10899-4, 2018/22214-6, 2018/18953-8]. We would like to thank Berthine 487 Khelifi , Cécile Sillard and Thierry Encinas from Grenoble Institute of Technology for their 488 expertise in providing SEM imaging, XPS and XRD analyses, respectively.

International audience; Green treatment of natural fibres is a major issue in paper, textile and biocomposites industries to design innovative and eco-friendly products. In this work, hierarchical structuring of flax woven fabrics by the adsorption of xyloglucan (XG) and cellulose nanocrystals (CNC) is studied. Indeed, CNC have high mechanical properties, high specific surface area and great potential for functionalization. The adsorption of XG and CNC has been investigated in terms of localization by confocal and scanning electron microscopy (SEM) and quantification through adsorption isotherms. Adhesion force measurements have also been performed by Atomic Force Microscopy (AFM). XG and CNC are homogeneously adsorbed on flax fabric and adsorption isotherms reach plateau values around 20 mg /gfibres for both. The pre-adsorption of XG on flax fabric influences the amount of adsorbed CNC in the high concentrations and also creates entanglements and strong interactions between XG and CNC with the formation of an extensible network.

The objective of this study is to broaden the knowledge about the effect of ozone, when introduced as a reactive gas in the flotation cell, on the deinking performance of printed papers as well as on the papermaking properties of recycled cellulosic fibers (physical and optical properties, papermaking ability). Trials, with high ozone dose (2.97% ozone/fibers w/w), have been investigated and conducted in a laboratory flotation cell pilot (15 L). Several mixtures of recovered papers have been studied: (i) an industrial mix made of 50%/50% magazines/newspapers, (ii) two wood-free recovered lignocellulosic fiber pulp models (lignin content lower than 15%) to limit the yellowing effect of lignified fibers, and (iii) a wood-free industrial pulp mixture composed of 90% office papers and 10% magazines. Tap water and model process water have been used to dilute the fibers before deinking. For a better understanding of the ozone reactivity, experiments have been also conducted on both types of waters in the absence of fiber. The main benefits of the ozone reactive flotation process are (1) the strong reduction of the effluent soluble COD of about 63% compared to air flotation in the case of the industrial pulp mixture deinking using the model process water, (2) the increase of the fiber yield by 1 point and (3) the preservation or the improvement of the papermaking properties of the recycled fibers. Ozone preferentially reacts with soluble contaminants, so that fibers and pulp papermaking properties are not affected. This process is utterly suitable for the deinking of wood-free papers., L’objectif de cette étude est d’accroître les connaissances de l’effet de l’ozone introduit comme gaz réactif dans le procédé de flottation sur les performances du désencrage de papiers imprimés ainsi que sur les propriétés papetières des fibres cellulosiques recyclées (propriétés physiques et optiques, aptitude papetière). Des essais à forte dose d’ozone (2,97% par rapport à la masse de fibres) ont été investigués et conduits dans une cellule de flottation pilote de laboratoire (15 L). Plusieurs mélanges de papiers récupérés ont été étudiés : (i) un mélange 50%/50% magazines/journaux, (ii) deux mélanges modèles à base de fibres vierges sans bois (taux de lignine inférieure à 15%) pour limiter l’effet du jaunissement des fibres lignifiées, et (iii) un mélange industriel sans bois composé de 90% de papiers de bureaux et 10% de magazines. L’eau du réseau et une eau de procédé modèle ont été utilisées pour diluer les fibres avant désencrage. Pour une meilleure compréhension de la réactivité de l’ozone, des essais ont également été conduits sur les deux types d’eaux, en l’absence de fibre. Les principaux avantages du procédé de flottation réactive à l'ozone sont (1) la forte réduction de la DCO soluble dans les effluents jusqu’à 63% par rapport à la flottation à l’air dans le cas d’essais avec des papiers industriels, en utilisant une eau de procédé modèle, (2) l’augmentation du rendement en fibres de 1 point et (3) une conservation ou amélioration des propriétés papetières des fibres recyclées. L’ozone réagit préférentiellement avec les contaminants solubles de sorte que les fibres ne sont pas affectées.Ce procédé est tout à fait adapté au désencrage de papiers imprimés sans bois.

Cellulose nanofibrils were efficiently produced from eucalyptus fibers using a combined NaOH and enzymatic treatment followed by a pilot scale grinding process. The structural changes of fibers were assessed after NaOH treatments at 5, 10 and 15 wt% concentrations. A progressive shift from a cellulose I to a cellulose II crystalline structure was observed with X-ray diffraction (XRD) and nuclear magnetic resonance (NMR). The further enzymatic hydrolysis was improved for the NaOH treated samples. The increase of crystallinity indices due to enzymatic hydrolysis was of + 4.7 %, + 3.5 %, and +10.3 % for samples treated with NaOH 5, 10 and 15 wt% respectively, and DP values were drastically reduced to 340, 190 and 166 respectively. A morphological analysis underlined an optimum with the combination of NaOH 10 wt% and enzymatic hydrolysis. This treatment followed by the grinding process resulted in CNF with a rigid structure, with diameters ranging from 10 to 20 nm and lengths between 150 and 350 nm. A multi-scale analysis enabled to study the impact of this combined treatment on CNF properties and energy consumption. A decrease in mechanical properties of nanopapers was observed for the combined treatment and NaOH treatment alone compared to enzymatic hydrolysis alone, with Young's modulus of 8.94, 4.84 and 11.21 GPa respectively. However, optical properties were improved, with transmittance values of 42.2, 15.4 and 7.1 % respectively. This new pretreatment can therefore lead to CNF with tunable properties depending on the application, with possible industrialization thanks to the reduction of energy needs.

Hemicelluloses are valuable sources of polysaccharides constituting 20-30% of wood. Since the nature and quantities of hemicelluloses vary in different tree species, their valorization is challenging. Kraft pulps still contain 15 to 30% of hemicelluloses. Among different chemical processes for removing hemicelluloses from kraft pulps, the most applicable is Cold Caustic Extraction, CCE, but its main disadvantage is the use of huge quantities of caustic soda. Another solution could be to use enzymatic processes which are selective and environmentally-friendly. The objectives of this thesis were to investigate the performance of enzymatic treatments to remove hemicelluloses from bleached kraft hardwood and softwood pulps and to characterize the hemicellulose oligomers extracted. The best results of hemicellulose extraction in single usage of xylanase and mannanase on starting pulps were: 14.8% and 22.3% for xylanase on hardwood and softwood pulps respectively and 1.1% and 7.9% for mannanase on hardwood and softwood pulp respectively. The relative extraction of hemicelluloses seemed easier from softwood than from hardwood pulp. The same result was obtained for CCE treatment of pulps.The use of both enzymes, either in a consecutive way or added together led to overall better xylan extraction from the softwood pulp, but no significant impact on the extraction of mannans. For hardwood pulp, the best result was obtained when xylanase and mannanase were added together, which implies a strong synergistic effect. The difference in arrangements supports probably the fact that the hemicelluloses have either different structures in the two wood species and/or do not show the same accessibility to enzymes.Applying a CCE treatment after the enzymatic treatment was much more efficient than CCE alone or enzymatic treatment alone: the content of hemicelluloses in the softwood pulp dropped from 13.7% to 6.2%, and from 24.3% to 7.0% for the hardwood pulp. One explanation could be that the enzymatic treatment has decreased the DP of hemicelluloses making them more easily solubilized by the CCE treatment. Regarding the characterization of the oligosaccharides released by the enzymatic treatments, it was shown that the xylanase treatment of hardwood pulp, led mainly (85% of the mass) to the extraction of short oligomers (average degree of polymerization of 3-4), and to a minor extent (15% of the mass) to a second family of molecules with an average DP of 15-18. When mannanase was applied on the softwood pulp, the released oligomers had an average DP of 1-3.The mass spectroscopy analysis showed the release of highly diverse components; from linear to non-linear oligomers with different combination of side-groups (acetyl groups, glucuronic acid groups, methylglucuronic acid groups) on xylans. Acetylated mannans could also be found.; Les hémicelluloses sont de précieuses sources de polysaccharides qui constitue 20 – 30 % du bois. Étant donné que la nature et les quantités d'hémicelluloses varient selon les espèces d'arbres, leur valorisation est difficile. Les pâtes kraft contiennent 15 – 30% d'hémicelluloses. Parmi les différents procédés chimiques pour éliminer les hémicelluloses des pâtes kraft, le plus applicable s’agit l'extraction alcaline à froid, CCE, mais son inconvénient principal est l'utilisation d'énormes quantités de soude. Alternativement, une autre solution pourrait être d'utiliser des procédés enzymatiques qui sont sélectifs et respectueux de l'environnement.La thèse avait pour objectifs d'étudier la performance des traitements enzymatiques afin d’éliminer les hémicelluloses des pâtes kraft blanchie de résineux et de feuillus et de caractériser les oligomères extraits d'hémicellulose. Les meilleurs résultats de l'extraction de l'hémicellulose en utilisant xylanase et mannanase, séparément, sur les pâtes initiales étaient : 14,8% et 22,3% pour la xylanase sur les pâtes de feuillus et de résineux, respectivement, et 1,1% et 7,9% pour la mannanase sur les pâtes de feuillus et de résineux, respectivement. L'extraction proportionnelle des hémicelluloses semble plus facile du bois résineux que du bois feuillu. Le même résultat a été obtenu pour le traitement CCE des pâtes.L'utilisation des deux enzymes, soit de la manière consécutive, soit ajoutée ensemble a mené à une meilleure extraction du xylane de la pâte de résineux, mais aucune influence significative sur l'extraction du mannane. Pour la pâte feuillue, le meilleur résultat a été obtenu lorsque la xylanase et la mannanase ont été ajoutées ensemble, ce qui implique un effet synergique fort. La différence de disposition confirme probablement que les hémicelluloses ont soit des structures différentes dans les deux bois feuillu et résineux et / ou ne présentent pas la même accessibilité aux enzymes.La réalisation d’un traitement CCE après le traitement enzymatique était beaucoup plus efficace que le CCE seul ou le traitement enzymatique seul : le contenu des hémicelluloses dans la pâte de résineux est baissé de 13,7% à 6,2%, et de 24,3% à 7,0% pour la pâte de feuillus. Une explication pourrait être que le traitement enzymatique a diminué le DP des hémicelluloses, les rendant solubilisées plus facilement par le traitement CCE.Concernant la caractérisation des oligosaccharides lancés par les traitements enzymatiques, il a été observé que le traitement de la pâte de feuillus par la xylanase résultait principalement (85% de la masse) à l'extraction d'oligomères courts (degré moyen de polymérisation de 3-4), et dans une moindre mesure (15% de la masse) à une deuxième famille de molécules avec un DP moyen de 15-18. En traitant par la mannanase sur la pâte de résineux, les oligomères lancés avaient un DP moyen de 1 à 3.L'analyse par spectroscopie de masse a montré la libération de composants très divers ; d'oligomères linéaires à non linéaires avec différentes combinaisons de groupes latéraux (groupes acétyle, groupes acide glucuronique, groupes acide méthylglucuronique) sur les xylanes. Des mannanes acétylés peuvent également être trouvés.

Hemicelluloses are valuable sources of polysaccharides constituting 20-30% of wood. Since the nature and quantities of hemicelluloses vary in different tree species, their valorization is challenging. Kraft pulps still contain 15 to 30% of hemicelluloses. Among different chemical processes for removing hemicelluloses from kraft pulps, the most applicable is Cold Caustic Extraction, CCE, but its main disadvantage is the use of huge quantities of caustic soda. Another solution could be to use enzymatic processes which are selective and environmentally-friendly. The objectives of this thesis were to investigate the performance of enzymatic treatments to remove hemicelluloses from bleached kraft hardwood and softwood pulps and to characterize the hemicellulose oligomers extracted. The best results of hemicellulose extraction in single usage of xylanase and mannanase on starting pulps were: 14.8% and 22.3% for xylanase on hardwood and softwood pulps respectively and 1.1% and 7.9% for mannanase on hardwood and softwood pulp respectively. The relative extraction of hemicelluloses seemed easier from softwood than from hardwood pulp. The same result was obtained for CCE treatment of pulps.The use of both enzymes, either in a consecutive way or added together led to overall better xylan extraction from the softwood pulp, but no significant impact on the extraction of mannans. For hardwood pulp, the best result was obtained when xylanase and mannanase were added together, which implies a strong synergistic effect. The difference in arrangements supports probably the fact that the hemicelluloses have either different structures in the two wood species and/or do not show the same accessibility to enzymes.Applying a CCE treatment after the enzymatic treatment was much more efficient than CCE alone or enzymatic treatment alone: the content of hemicelluloses in the softwood pulp dropped from 13.7% to 6.2%, and from 24.3% to 7.0% for the hardwood pulp. One explanation could be that the enzymatic treatment has decreased the DP of hemicelluloses making them more easily solubilized by the CCE treatment. Regarding the characterization of the oligosaccharides released by the enzymatic treatments, it was shown that the xylanase treatment of hardwood pulp, led mainly (85% of the mass) to the extraction of short oligomers (average degree of polymerization of 3-4), and to a minor extent (15% of the mass) to a second family of molecules with an average DP of 15-18. When mannanase was applied on the softwood pulp, the released oligomers had an average DP of 1-3.The mass spectroscopy analysis showed the release of highly diverse components; from linear to non-linear oligomers with different combination of side-groups (acetyl groups, glucuronic acid groups, methylglucuronic acid groups) on xylans. Acetylated mannans could also be found., Les hémicelluloses sont de précieuses sources de polysaccharides qui constitue 20 – 30 % du bois. Étant donné que la nature et les quantités d'hémicelluloses varient selon les espèces d'arbres, leur valorisation est difficile. Les pâtes kraft contiennent 15 – 30% d'hémicelluloses. Parmi les différents procédés chimiques pour éliminer les hémicelluloses des pâtes kraft, le plus applicable s’agit l'extraction alcaline à froid, CCE, mais son inconvénient principal est l'utilisation d'énormes quantités de soude. Alternativement, une autre solution pourrait être d'utiliser des procédés enzymatiques qui sont sélectifs et respectueux de l'environnement.La thèse avait pour objectifs d'étudier la performance des traitements enzymatiques afin d’éliminer les hémicelluloses des pâtes kraft blanchie de résineux et de feuillus et de caractériser les oligomères extraits d'hémicellulose. Les meilleurs résultats de l'extraction de l'hémicellulose en utilisant xylanase et mannanase, séparément, sur les pâtes initiales étaient : 14,8% et 22,3% pour la xylanase sur les pâtes de feuillus et de résineux, respectivement, et 1,1% et 7,9% pour la mannanase sur les pâtes de feuillus et de résineux, respectivement. L'extraction proportionnelle des hémicelluloses semble plus facile du bois résineux que du bois feuillu. Le même résultat a été obtenu pour le traitement CCE des pâtes.L'utilisation des deux enzymes, soit de la manière consécutive, soit ajoutée ensemble a mené à une meilleure extraction du xylane de la pâte de résineux, mais aucune influence significative sur l'extraction du mannane. Pour la pâte feuillue, le meilleur résultat a été obtenu lorsque la xylanase et la mannanase ont été ajoutées ensemble, ce qui implique un effet synergique fort. La différence de disposition confirme probablement que les hémicelluloses ont soit des structures différentes dans les deux bois feuillu et résineux et / ou ne présentent pas la même accessibilité aux enzymes.La réalisation d’un traitement CCE après le traitement enzymatique était beaucoup plus efficace que le CCE seul ou le traitement enzymatique seul : le contenu des hémicelluloses dans la pâte de résineux est baissé de 13,7% à 6,2%, et de 24,3% à 7,0% pour la pâte de feuillus. Une explication pourrait être que le traitement enzymatique a diminué le DP des hémicelluloses, les rendant solubilisées plus facilement par le traitement CCE.Concernant la caractérisation des oligosaccharides lancés par les traitements enzymatiques, il a été observé que le traitement de la pâte de feuillus par la xylanase résultait principalement (85% de la masse) à l'extraction d'oligomères courts (degré moyen de polymérisation de 3-4), et dans une moindre mesure (15% de la masse) à une deuxième famille de molécules avec un DP moyen de 15-18. En traitant par la mannanase sur la pâte de résineux, les oligomères lancés avaient un DP moyen de 1 à 3.L'analyse par spectroscopie de masse a montré la libération de composants très divers ; d'oligomères linéaires à non linéaires avec différentes combinaisons de groupes latéraux (groupes acétyle, groupes acide glucuronique, groupes acide méthylglucuronique) sur les xylanes. Des mannanes acétylés peuvent également être trouvés.

International audience; This study presents the impregnation in supercritical carbon dioxide (scCO 2) of nanocellulose-based structures with thymol as a natural antimicrobial molecule to prepare bioactive biosourced materials. First, cellulose nanofibrils (CNFs) were used to produce four types of materials (nanopapers, cryogels from water or tert-butyl alcohol suspensions and aerogels) of increasing specific surface area up to 160 m 2 .g-1 thanks to the use of different processes, namely vacuum filtration, freeze-drying and supercritical drying. Secondly, these CNF-based structures were impregnated with thymol in scCO 2 medium using relatively low temperature and pressure of 40°C and 100 bars during 1 hour. The amount of impregnated thymol in the different CNF-materials was investigated by fluorescence spectroscopy, 13 C NMR analysis and gas

International audience; The recent emergence of bio-based nanocomposites makes perfect sense from a technical and environmental point of view. Cellulose nanocrystals (CNCs) are novel bio-based nanomaterials with a wide range of beneficial properties. Their biodegradability, crystallinity, high surface area, and mechanical strength, as well as their highly reactive surface, make them ideal materials as nanofillers in polymeric matrices. However, most the bio-based polymers are hydrophobic, and the hydrophilicity of CNC is therefore a challenge to their incorporation in such matrices. In this study, a new procedure for surface modification of CNC with long aliphatic chains [lauric acid (12 carbons) and stearic acid (18 carbons)] was developed that limits the use of petro-chemicals and facilitates their potential recycling. A study of the dispersion state of CNC in acetone was performed first. Then, grafting efficiency was highlighted by several techniques and quantification of the amount of grafted fatty chains was investigated. Degrees of substitution on the bulk and on the surface of the CNC were calculated between 0.1 and 0.3, which provided enough grafted functions to confer hydrophobic behavior to modified CNCs, as highlighted by the increasing of contact angle from 65° for neat CNC to 80° after modification. Finally, conservation of CNC crystalline structure and morphology was proved by both X-ray diffraction and transmission electron microscopy analyses. Modified CNCs exhibit a crystallinity index close to 86% and length of approximately 350 nm. Thus, crystalline hydrophobic cellulosic nanomaterials were prepared using a more environmentally friendly procedure than those classically found in the literature.