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Implantable devices powered by batteries have been used for sixty years.

This study aimed to evaluate the properties of cellulose nanofibers (CNFs) with different hemicellulose contents and cellulose II polymorphs. A link was found between these polysaccharides and the properties of CNFs. A decrease in crystallinity (from 69 to 63%) and changes in the crystalline structure of cellulose subjected to an alkaline environment were observed, promoting the partial conversion of cellulose I to cellulose II (from 2 to 42%) and preventing CNFs production at NaOH concentrations higher than 5%. Most treatments showed pseudoplastic fluid behavior, except for the 10% NaOH treatment over 2 h, which showed Newtonian fluid behavior. The quality index of the reference CNFs (TEMPO-oxidized) was the highest (80 ± 3), followed by that of the 5% NaOH-treated (68 ± 3 and 22% energy savings compared to the untreated sample), and the untreated (63 ± 3) samples; and the 10% NaOH treatments had quality indices of 51 ± 3 and 32 ± 1, respectively.

openaire: EC/H2020/788489/EU//BioELCell Natural biopolymers have become key players in the preparation of biodegradable food packaging. However, biopolymers are typically highly hydrophilic, which imposes limitations in terms of barrier properties that are associated with water interactions. Here, we enhance the barrier properties of biobased packaging using multilayer designs, in which each layer displays a complementary barrier function. Oxygen, water vapor, and UV barriers were achieved using a stepwise assembly of cellulose nanofibers, biobased wax, and lignin particles supported by chitin nanofibers. We first engineered several designs containing CNFs and carnauba wax. Among them, we obtained low water vapor permeabilities in an assembly containing three layers, i.e., CNF/wax/CNF, in which wax was present as a continuous layer. We then incorporated a layer of lignin nanoparticles nucleated on chitin nanofibrils (LPChNF) to introduce a complete barrier against UV light, while maintaining film translucency. Our multilayer design which comprised CNF/wax/LPChNF enabled high oxygen (OTR of 3 ± 1 cm3/m2·day) and water vapor (WVTR of 6 ± 1 g/m2·day) barriers at 50% relative humidity. It was also effective against oil penetration. Oxygen permeability was controlled by the presence of tight networks of cellulose and chitin nanofibers, while water vapor diffusion through the assembly was regulated by the continuous wax layer. Lastly, we showcased our fully renewable packaging material for preservation of the texture of a commercial cracker (dry food). Our material showed functionality similar to that of the original packaging, which was composed of synthetic polymers.

Nanofibrilated cellulose (NFC) films have potential to replace synthetic polymers as flexible films for packaging. However, NFC is hydrophilic and water acts as plasticizer decreasing the stiffness of the films and reducing its barrier effectiveness against water vapor and oxygen. Here we describe the surface modification of cellulose films with blocked diisocyanates through a dipping and heating process not requiring the previous drying of the materials. The reactions were conducted at 170 °C for a few minutes during which deblocking led to a new urethane bond formation with NFC surface hydroxyl groups, thus hydrophobizing the films. A remarkable enhancement in water repellent properties was confirmed by water contact angles higher than 110° and water vapor transmission rate (WVTR) of 40 g/m2 day, which is very low when compared to similar materials, representing a reduction of 74% with respect to the non- modified films.

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In the current context, the development of bio-based and high-performance materials is one of the main research priorities. This study aims to combine the outstanding properties of cellulose nanofibrils (CNFs) or nanocrystals (CNCs) with those of bio-based poly(lactic acid) (PLA). Three-phase multilayered materials (TMLs) were built up by complexing a dry CNF- or CNC-based film with two PLA sheets, using a heat-pressing process. Before the preparation of the nanocellulosic films, CNFs and CNCs were modified by the adsorption of a rosin-based nanoemulsion. The rosin mixture as a natural compound is of interest because of its low cost, renewability, hydrophobicity, and its antimicrobial and antioxidant properties. After demonstrating the efficiency of the complexing procedure, we investigated the barrier properties of the multilayered materials against both oxygen and water vapor, with highly encouraging results. In fact, the presence of nanocellulose as an inner layer between the two PLA films significantly enhanced the oxygen barrier, with a decrease in oxygen permeability comprised between 84 and 96% and between 44 and 50% for neat nanocelluloses and nanocelluloses with rosins as the inner layer, respectively. On the other hand, the antioxidant properties of the final multilayered materials including rosins were highlighted, with a highly encouraging radical scavenging activity close to 20%. Because of the simplicity and the efficiency of the proposed method, this study paves the way toward the development of hybrid multimaterials that could be highly attractive for food packaging applications.

The biocompatibility and very high specific area of cellulose nanofibrils (CNF) are properties of high interest for the development of active substrates for new medical device development. Enzyme pretreated CNF (CNF-e) can be self-organized into nanostructured membranes that are suitable for active principle ingredients (API) encapsulation through adsorption phenomena. In addition, tunable surface chemistry of CNF-e, allow for covalent immobilization of API. In this work, ciprofloxacin is integrated to CNF-e membranes according to two different strategies. The first one relies only on adsorption mechanisms; ciprofloxacin is encapsulated in the bulk before the membrane formation by solvent casting. The influence of the membrane properties and preparation parameters such as grammage, thickness and drying technique, are assessed with water uptake measurements and API release experiments. The second strategy deals with the covalent immobilization of ciprofloxacin directly onto CNF-e membrane. The two kinds of membranes are then compared in terms of antibacterial activity, in both static and dynamic conditions. Thick CNF-e membranes loaded with adsorbed ciprofloxacin that were overdried (2 h, 150 °C) prove to be more resistant in liquid medium and present a more prolonged drug release. However, these membranes rapidly lost their antibacterial activity, while CNF-e membranes with covalently immobilized ciprofloxacin remain contact active for several days. These 100% CNF active nanostructured membranes can be used as new wound dressing for topical application.

In this study, the grafting of 1-methyl-3-phenylpropylamine (1-M-3-PP) on cellulose nanocrystals (CNCs) via a two-step reaction route was investigated and compared with physico-chemical surface adsorption. The first step involved subjecting CNCs to a 2,2,6,6-Tetramethyl-1-piperidinyloxy (TEMPO)-mediated oxidation. The carboxylic groups present on recovered oxidized TEMPO-CNC were quantified by several characterization methods (conductometric titration, elemental analysis, and X-ray photoelectron spectroscopy), and a degree of oxidation close to 0.2 was found. The second step was an amidation reaction carried out in an aqueous medium under mild conditions and in the presence of N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide (EDC)/N-hydroxysuccinimide (NHS) as catalyst. The recovered modified CNCs after amidation reaction with 1-M-3-PP (CNC-1-M-3-PP) were extensively washed and then characterized. The amount of grafted molecules was determined by several techniques like X-ray photoelectron spectroscopy (XPS), and the calculated degree of substitution was found to be close to 0.05 with respect to the bulk CNC. This low amount is sufficient to enhance the modified CNC dispersion and their colloidal stabilization in organic solvents, allowing the preparation of nanocomposites. Furthermore, such CNC-1-M-3-PP units with aromatic molecules attached to it can find applications in barrier materials in which the sorption of aromatic molecules can be very useful.

Lignin-cellulose nanofibrils (LCNF) are of attracting an increasing interest due to the benefits of maintaining the lignin in the nanomaterial composition. The production of LCNF requires considerable energy consumption, which has been suppressed employing pretreatment of biomass, in which it highlights those that employ enzymes that have the advantage of being more environmentally friendly. Some negative aspects of the presence of lignin in the fiber to obtain cellulose nanofibrils is that it can hinder the delamination of the cell wall and act as a physical barrier to the action of cellulase enzymes. This study aimed to evaluate the impact of a combined enzymatic pretreatment of laccase and endoglucanase for high content lignin LCNF production. The morphological and chemical properties, visual aspect and stability, crystallinity, mechanical properties, rheology, barrier properties and quality index were used to characterize the LCNF. The laccase loading used was efficient in modifying the lignin to facilitate the action of the endoglucanase on cellulose without causing the removal of this macromolecule. This pretreatment improved the quality of LCNF (61 ± 3 to 71 ± 2 points) with an energy saving of 42% and, therefore, this pretreatment could be suitable for industrial production for a variety of applications.

openaire: EC/H2020/788489/EU//BioELCell Funding Information: The authors would like to thank S-Fly and Die Wurm Farm for providing the raw materials needed for this study and Tuyen Nguyen for the fluidization of the different ChNFs. LGP2 is part of the LabEx Tec 21 (Investissements d’Avenir - grant agreement no. ANR-11-LABX-0030) and of the PolyNat Carnot Institute (Investissements d’Avenir - grant agreement no. ANR-16-CARN-0025-01). This work was supported by Grenoble INP, “Bourse Présidence”, and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 788489). O.J.R. also acknowledges the Canada Excellence Research Chair initiative and the Canada Foundation for Innovation (CFI). Support from the Austrian Biorefinery Center Tulln (ABCT) is gratefully acknowledged. Publisher Copyright: © 2021 American Chemical Society. Nowadays, environmental concerns make us rethink the way that we live and eat. In this regard, alternative protein sources are emerging; among them, insects are some of the most promising alternatives. Insect farming is still an infant industry, and to improve its profitability and environmental footprint, valorization of the byproducts will be a key step. Chitin as the main polysaccharide in the exoskeleton of insects has a great potential in this regard and can be processed into high value-added materials. In this study, we extracted and fibrillated chitin fibers from fly larvae (Hermetia illucens) and compared them with commercial chitin from shrimp shells. A mix of chitin and cellulose fibers was also extracted from mealworm farming waste. The purified chitinous fibers from different sources had similar chemical structures as shown by Fourier transform infrared and nuclear magnetic resonance spectroscopies. After mechanical fibrillation, the nanostructures of the different nanofibers were similar with heights between 9 and 11 nm. Chitin nanofibers (ChNFs) from fly larvae presented less nonfibrillated fiber bundles than the shrimp-derived analogue, pointing toward a lower recalcitrance of the fly larvae. ChNF suspensions underwent different film-forming protocols leading to films with tensile strengths of 83 ± 7 and 71 ± 4 MPa for ChNFs from shrimp and fly, respectively. While the effect of the chitin source on the mechanical properties of the films was demonstrated to be negligible, the presence of cellulose nanofibers closely mixed with ChNFs in the case of mealworm led to films twice as tough. Our results show for the first time the feasibility of producing ChNFs from insect industry byproducts with high potential for valorization and integral use of biomass.

The study deals with the synthesis of thermally reversible hydrogels from modified cellulose nanofibers via the Diels-Alder “click” reaction in an aqueous medium. “Never-dried” cellulose fibres derived from hardwood were submitted to shearing and surface TEMPO-oxidation before being modified with furfurylamine. The ensuing pendant furan moieties were reacted with a water-soluble bismaleimide via Diels-Alder coupling at 65 °C to produce a hydrogel, whose deconstruction was induced by the corresponding retro-Diels-Alder reaction carried out at 95 °C. Differential scanning calorimetry and rheological measurement were used to characterize the hydrogels. These aqueous cellulosic materials should provide original applications in such areas as strong paper-based artefacts and biocompatible gels.

Phosphorylated cellulose nanofibrils (CNFs) were produced using a twin-screw extruder (TSE). The energy efficiency was compared with that of an ultra-fine grinder (UFG). CNFs at different solid contents were produced (10 wt% for the TSE and 2 wt% for the UFG), and their quality was compared using several characterization tests, such as optical microscopy, atomic force microscopy or MorFi fiber analyser. CNF nanopapers with high a Young’s modulus (14 GPa) and high transparency were successfully manufactured using CNFs produced by the TSE. The efficiency of the TSE was improved by using phosphorylated pulp instead of mechano-enzymatically treated pulp. The results show that phosphorylated CNFs can be easily produced at the industrial scale via twin-screw extrusion and present new functionalities such as fire-retardant properties, which are useful in many applications.

In this study, an innovative and green process to produce cellulose nanofibers (CNFs) is proposed. CNFs are usually produced via mechanical, enzymatic, and/or chemical treatment such as (2,2,6,6-te...

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.

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.

openaire: EC/H2020/788489/EU//BioELCell Cellulose (CNF) and chitin (ChNF) nanofibers are known to form materials that are both tough and strong. In this study, we hypothesize that the inertness of networks produced from CNF and ChNF makes them ideal templates for heterogeneous reactions and in situ formation of nanoarchitectures. We expand nanoparticle templating on polysaccharide colloids by introducing a new and facile process that leads to the growth of organic nanoparticles on CNF and ChNF in aqueous media. The process, based on solvent shifting supported on solid interfaces, is demonstrated by direct observation of lignin nanoparticles that are further used for their photocatalytic activity. Importantly, the dynamics of nanoparticle nucleation and growth is correlated with the surface chemistry of the templating nanopolysaccharides. Electrostatic repulsion between the deprotonated lignin molecules and the slightly negative CNF support led to limited adsorption and was effective in producing free (nonbound) lignin nanoparticles (28 ± 7 nm) via precipitation. In contrast, the stronger interfacial interactions between the positively charged ChNF and lignin molecules facilitated instantaneous and extensive lignin adsorption, followed by nucleation and growth into relatively larger nanoparticles (46 ± 17 nm). The latter were homogeneously distributed and strongly coupled to the ChNF support. Overall, we introduce lignin nanoparticle nucleation and growth on renewable nanopolysaccharides, offering an effective route toward in situ synthesis of highly functional fibrils and related cohesive films that offer a great potential in packaging and other applications.

Nowadays, drug encapsulation and drug release from cellulose nanofibrils systems are intense research topics, and commercial grades of cellulose nanomaterials are currently available. In this work we present an ester-containing prodrug of metronidazole that is covalently bound to cellulose nanofibrils in aqueous suspension through a two-step immobilization procedure involving green chemistr y principles. The presence of the drug is confirmed by several characterization tools and methods such as Raman spectroscopy, elemental analysis, Dy-namic Nuclear Polarization enhanced NM R . This technique allow s enhancing the sensitivity of NM R by several orders of magnitude. It has been used to study cellulose nanofibrils substrates and it appears as the ultimate tool to confirm the covalent nature of the binding through thiol-yne click chemistry. Moreover, the ester function of the immobilized prodrug can be cleaved by specific enzyme activity thus allowing controlled drug release.

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.

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.

International audience; Cellulose nanocrystals (CNCs) are used to design nanocomposites because of their high aspect ratio and their outstanding mechanical and barrier properties. However, the low compatibility of hydrophilic CNCs with hydrophobic polymers remains a barrier to their use in the nanocomposite field. To improve this compatibility, poly(glycidyl methacrylate) (PGMA) was grafted from CNCs containing α-bromoisobutyryl moieties via surface-initiated atom transfer radical polymerization. The novelty of this research is the use of a reactive epoxy-containing monomer that can serve as a new platform for further modifications or crosslinking. Polymer-grafted CNC-PGMA-Br prepared at different polymerization times were characterized by XRD, DLS, FTIR, XPS and elemental analysis. Approximately 40 % of the polymer at the surface of the CNCs was quantified after only 1 h of polymerization. Finally, nanocomposites prepared with 10 wt% CNC-PGMA-Br as nanofillers in a poly(lactic acid) (PLA) matrix exhibited an improvement in their compatibilization based on SEM observation.

Over the last decades, the development of renewable resources of fibres was intensified, which amplified the market request of such a raw material. This is due to three potential advantages associated with these natural substances, namely: very cheap, bio-renewable and their availability in large quantities with various varieties forms. This chapter is devoted to the discussion of the potential valorization of the date palm waste to prepare fibres and nanofibres. This agricultural waste has lately noticed considerable attention, as an important source to produce cellulosic fibres, especially in forest-poor regions. The morphologies features, the chemical composition of date palm and their comparison with different lignocellulosic fibres sources are described. Then, the delignification methods and characterization of fibres from date palm are also presented. Finally, the preparation of nanocellulose (Cellulose nanocrystals (CNCs) and cellulose nanofibres (CNF)) and their use as nanofibre-reinforced nanocomposite materials will be detailed and discussed.

Polyurethanes are synthesized from polyols, which can be fossil- or plant-sourced. The goal of this study was to investigate how the use of plant-sourced polyols, i.e., the ricinoleic acid triglyceride (the main component of castor oil, CO) and lignosulfonate, impacts the properties of the materials, as well as of their composites reinforced with sisal fibers. To reach this objective, the properties of polyurethanes from plant-sourced polyols were compared with those of their counterparts synthesized using fossil-sourced diethylene glycol (DEG) and polyethylene glycol (PEG). As far as is known, this approach is unheard-of. Polyurethanes and lignopolyurethanes (neat PUs and LigPUs) were synthesized under temperature and compression molding from CO, DEG, and PEG (PUs), and in LigPUs, 30 % of the polyols were replaced by lignosulfonate. Under the same conditions, composites were formed simultaneously with the syntheses after adding sisal fibers (30 % by weight, 3 cm in length) to the reagents. A notable characteristic is the impact strength of the neat PU and PU sisal composites in which PEG (approximately 750 Jm−1and 850 Jm−1, respectively) and CO (unfractured and approximately 850 Jm−1, respectively) were used. Flexural tests showed that the use of CO as a polyol in the synthesis of the neat PUs and LigPUs and composites imparted elastomeric characteristics to the materials. Similar properties were noted when PEG was used as a polyol, except when it was used together with lignosulfonate in the sisal reinforced composite. A high content of renewable raw material was used in the LigPU sisal fiber composites, meeting expectations regarding the sustainability of the processes, as well as the potential to contribute to the development of the bioeconomy. The materials were prepared using renewable reagents largely available, with no solvent or catalyst use, through a simple process, and no byproducts generated. These features favor the scaling-up of the process. Also, the bio-based materials exhibited good and diverse properties, which qualify them for various applications in which polyurethanes obtained only from fossil-sourced raw materials are used.

International audience; Enzymatic biofuel cells are emerging technologies which gain a lot of interest as a power source for implantable devices. Effective enzyme wiring and simplification of the cell architecture are the main limitations of the fuel cell development nowadays. In the present study, spray coating was used as a reliable process to produce flexible biocathodes. That was achieved through spray coating of a conductive ink formulated by surfactant assisted carbon nanotubes dispersion. A thin continuous layer of carbon nanotubes (CNTs) was successfully coated on top of a gas diffusion layer paper. The film thickness was modulated by varying the CNT load in the ink and the number of deposited layers. It varied between 1 and 7.8 μm for a number of deposited layers between 5 and 100. Laccase enzyme was then wired to printed CNT electrodes thanks to the host-guest interaction between the hydrophobic pocket of laccase and pyrene-adamantane. Electrochemical investigations showed that laccase was effectively wired to the CNTs and presented a favorable orientation toward oxygen reduction. The biocathode current density was dependent of the number of deposited CNT layers and reached an optimum at 170 μA cm−2 for 50 deposited layers.

Process simulation is a useful tool that has been widely used to analyze, design and optimize energy balances in chemical technologies including those related to biomass processing, biorefinery processes and chemical engineering. The presented data set serves as basis for the simulation of chitin purification, nanofibers and nanocrystals production processes, considering laboratory experimental procedures described in previous experimental articles.

Superhydrophobic surfaces have high potential in self-cleaning and anti-fouling applications. We developed a one-step superhydrophobic coating formulation containing sodium oleate (NaOl), hydrophobized precipitated calcium carbonate and biobased cellulose nanofibrils (CNFs) hydrophobized with either alkyl ketene dimer (AKD) or amino propyl trimethoxy silane (APMS) as a binder to fix and distribute the particles. Coatings were made on paperboard and the wetting behavior of the surface was assessed. Static, advancing and receding contact angles with water as well as roll-off and water shedding angle were compared to coatings made with styrene butadiene latex as binder instead of CNFs. Modifications with alkyl ketene dimer showed most promising results for a viable process in achieving superhydrophobic paperboard but required reformulation of the coating with optimized and reduced amount of NaOl to avoid surfactant-induced wetting via excess NaOl. A static water contact angle of 150° was reached for the CNF-AKD. The use of CNFs enables the improvement of coating quality avoiding cracking with the use of nanocellulose as a renewable binder.

International audience; Large mineral fillers have long been used in papermaking for many reasons. The finish of the writing and printing paper depends on using the fillers as internal or surface treatments. During this study, Tamarisk sp. and Prunus amygdalus pulp-filled papers with raw phosphogypsum (PG) and calcined PG (CPG) at different percentages were studied. First, the prepared minerals (treated and untreated ones) were characterized by different analytical methods such as SEM and EDS. Subsequently, different handsheets with a basis weight 60 g−2 were prepared on a Rapid Khöten sheet former following the standard method. The added amounts of PG and CPG fillers were included from 0% to 15% based on the pulp. The effects of incorporation as well as the quality fillers into physical and optical properties were assessed. It can be deduced that the incorporation of CPG at 800 °C improved filler retention by as high as 92%, and the optical properties of the filled paper was strikingly enhanced, while the strength properties were practically negatively influenced. It was clear that calcinationstepsreduce the fiber–filler–fiber bond. Thus, results are in accordance with the SEM observation, which confirmed the obtained physical properties.

International audience; The present study investigated the preparation of biomatrices from Stipa tenacissima L. and its valorization for fiberboard application. Resins were produced by extracting lignin from the Stipa tenacissima L. black liquor by soda process and combining it with glyoxal as crosslinking agent to produce lignin-glyoxal-resin (LGR). The matrix was characterized by several methods, such as FTIR and ATG/ATD, and then mixed with date palm rachis as reinforcing fibers in different proportions of 30 and 50% (w/w with respect to the matrix) to produce biodegradable composite materials. Then, their thermal and mechanical properties were determined, using differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA). The results obtained show that date palm rachis particles were effective in enhancing the thermo-mechanical properties of the thermoset matrix.

International audience; During the last two decades, interest in cellulosic nanomaterials has greatly increased. Among these nanocelluloses, cellulose nanocrystals (CNC) exhibit outstanding properties. Indeed, besides their high crystallinity, cellulose nanocrystals are interesting in terms of morphology with high aspect ratio (length 100–1000 nm, width 2–15 nm), high specific area, and high mechanical properties. Moreover, they can be used as rheological modifier, emulsifier, or for barrier properties, and their surface chemistry opens the door to numerous feasible chemical modifications, leading to a large panel of applications in medical, electronic, composites, or packaging, for example. Traditionally, their extraction is performed via monitored sulfuric acid hydrolysis, leading to well-dispersed aqueous CNC suspensions; these last bearing negative charges (half-sulfate ester groups) at their surface. More recently, natural chemicals called deep eutectic solvents (DESs) have been used for the production of CNC in a way of green chemistry, and characterization of recovered CNC is encouraging.

The aim of this work was to study the cellulose fibers deconstruction by twin-screw extrusion with in situ enzymatic hydrolysis via bioextrusion, for cellulose nanofibrils (CNF) production. Cellulose pulp was extruded with an optimized screw profile, with or without (reference) the addition of an enzymatic solution. An increase of crystallinity index from 67.0% to 73.7% and decrease of DP from 1003 to 419 were observed with bioextrusion. Direct activity measurements of the enzyme confirmed its activity during the process (sugar content increasing from 0.07 ± 0.004 to 2.38 ± 0.003 mg/mL) and after the process (specific activities around 0.20 CMCU/mL). Enzymes were not deactivated during bioextrusion and could be recycled. CNF properties were higher with bioextrusion compared to reference (respective quality indices of 55.5 ± 2.7 and 39.8 ± 2.8), with a lower energy consumption. This proof of concept could be optimized for the industrial production of highly concentrated CNF.