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openaire: EC/H2020/788489/EU//BioELCell Funding Information: We are thankful for funding support from Commission H2020 program ERC Advanced Grant (No. 788489, BioELCell), the Canada Excellence Research Chair initiative and the Canada Foundation for Innovation (CFI). We are grateful for the support by the FinnCERES Materials Bioeconomy Ecosystem. B. Zhao is grateful for the financial support from the China Scholarship Council (Project #201702640280) and NordForsk Project 82214 “High-Value Products from Lignin”. The authors thank L. Greca for providing the lignin microparticles and for discussions on their oxidative thermostabilization. The authors thank I. Schlapp-Hackl for assisting in the installation of the CO adsorption device. We also acknowledge J. Campbell for XPS measurements. 2 Publisher Copyright: © 2021 The Authors. Published by American Chemical Society. Copyright: Copyright 2021 Elsevier B.V., All rights reserved. Multiscale carbon supraparticles (SPs) are synthesized by soft-templating lignin nano- and microbeads bound with cellulose nanofibrils (CNFs). The interparticle connectivity and nanoscale network in the SPs are studied after oxidative thermostabilization of the lignin/CNF constructs. The carbon SPs are formed by controlled sintering during carbonization and develop high mechanical strength (58 N·mm-3) and surface area (1152 m2·g-1). Given their features, the carbon SPs offer hierarchical access to adsorption sites that are well suited for CO2 capture (77 mg CO2·g-1), while presenting a relatively low pressure drop (∼33 kPa·m-1 calculated for a packed fixed-bed column). The introduced lignin-derived SPs address the limitations associated with mass transport (diffusion of adsorbates within channels) and kinetics of systems that are otherwise based on nanoparticles. Moreover, the carbon SPs do not require doping with heteroatoms (as tested for N) for effective CO2 uptake (at 1 bar CO2 and 40 °C) and are suitablefor regeneration, following multiple adsorption/desorption cycles. Overall, we demonstrate porous SP carbon systems of low cost (precursor, fabrication, and processing) and superior activity (gas sorption and capture).

The interfacial bonding and structure at the nanoscale in the polymer–clay nanocomposites are essential for obtaining desirable material and structure properties. Layered nanocomposite films of cellulose nanofibrils (CNFs)/montmorillonite (MTM) were prepared from the water suspensions of either CNFs bearing quaternary ammonium cations (Q-CNF) or CNFs bearing carboxylate groups (TO-CNF) with MTM nanoplatelets carrying net surface negative charges by using vacuum filtration followed by compressive drying. The effect of the ionic interaction between cationic or anionic charged CNFs and MTM nanoplatelets on the structure, mechanical properties, and flame retardant performance of the TO-CNF/MTM and Q-CNF/MTM nanocomposite films were studied and compared. The MTM nanoplatelets were well dispersed in the network of TO-CNFs in the form of nanoscale tactoids with the MTM content in the range of 5–70 wt %, while an intercalated structure was observed in the Q-CNF/MTM nanocomposites. The resulting TO-CNF/MTM nanocomposite films had a better flame retardant performance as compared to the Q-CNF/MTM films with the same MTM content. In addition, the effective modulus of MTM for the TO-CNF/MTM nanocomposites was as high as 129.9 GPa, 3.5 times higher than that for Q-CNF/MTM (37.1 GPa). On the other hand, the Q-CNF/MTM nanocomposites showed a synergistic enhancement in the modulus and tensile strength together with strain-to-failure and demonstrated a much better toughness as compared to the TO-CNF/MTM nanocomposites.

Plant-based cellulosic materials are intriguing building blocks for functional materials, and sustainable nanocellulose production strategies have been intensively explored. Most of the existing strategies, however, suffer from the fact that highly energy-intensive fiber fibrillation yields a nanocellulose gel containing more than 95% water. We showcase a high throughput production method for nanocellulose, which primarily exploits the efficiency of enzymatic actions to disintegrate pulp fibers at a notable high solid content (25 wt %) without the need for high shear disintegration. The main enzyme activity exploited was cellobiohydrolase with the aid of endoglucanase. A pastelike fibril network is postulated to be formed through a peeling-type of reaction induced by the combined action of the enzymes used and fiber-fiber friction, with a yield of approximately 85%. Based on scanning electron microscopy and atomic force microscopy analyses, the formed nanocellulose can be classified as microfibrillated cellulose (i.e., cellulose microfibrils). Solid-state NMR and X-ray diffraction investigations revealed that the fibril morphology remained mostly intact. Our intriguing finding of a fraction with nanosized rodlike cellulose particles shows the power of enzymes in nanocellulose production. Our approach to producing nanocellulose at a high solid content in a much less energy-intensive manner puts forward the sustainable production of nanocellulose.

Starch and derivatives thereof have proven their usefulness in paper coating processes. Among these derivatives, cationic starch has been widely used in the paper industry as a flocculation, dispersion and ink fixing agent. In another context, nanoscale cellulosic materials have been shown to improve the strength, retention of fillers, the barrier properties of packaging paper products, and printing qualities. This review summarizes the recent studies on the general components used in paper coating, describes the conventional and alternative synthetic processes of cationic starches and nanocellulose, and deals with their current and potential applications in papermaking, focusing primarily on surface treatments. Moreover, environmental applications have been considered to expand the understanding and usefulness of these materials. Further research on modified polysaccharides is encouraged to replace, in a feasible way, petro-based components of coating formulations, and to provide paper surfaces with new properties.

Films formed from cellulose nanofibrils (CNFs) are known to be good barrier materials against oxygen, but they lose this feature once placed in humid conditions. To tackle this issue, we applied an optimized pressing condition under elevated temperature to increase the films&rsquo, density and improve their barrier performance. Furthermore, a water barrier coating was employed on the surfaces to control the moisture uptake at high relative humidity (RH). Neat self-standing films of CNF with the basis weight of 70 g/m2 were made through a filtration technique and pressed for 1 hour at 130 &deg, C. The resulting nanostructures were covered on both sides using a water-borne barrier layer. Hot-pressing resulted in a significant reduction in oxygen transmission rate (OTR) values, from 516.7 to 3.6 (cm3/(m2&middot, day)) and to some degree, helped preserve the reduced oxygen transmission at high relative humidity. Introducing 35 g/m2 of latex coating layer on both sides limited the films&rsquo, swelling at 90% RH for about 4 h and maintained the OTR at the same level. A finite element model was used to predict the dynamic uptake of water into the systems. The model was found to over-predict the rate of water uptake for uncoated samples but gave the correct order of magnitude results for samples that were coated. The obtained data confirmed the positive effect of hot-pressing combined with coating to produce a film with low oxygen transmission rate and potential to maintain its oxygen barrier feature at high relative humidity.

Transmembrane protein integrins play a key role in cell adhesion. Cell-biomaterial interactions are affected by integrin expression and conformation, which are actively controlled by cells. Although integrin structure and function have been studied in detail, quantitative analyses of integrin-mediated cell-biomaterial interactions are still scarce. Here, we have used atomic force spectroscopy to study how integrin distribution and activation (via intracellular mechanisms in living cells or by divalent cations) affect the interaction of human pluripotent stem cells (WA07) and human hepatocarcinoma cells (HepG2) with promising biomaterials-human recombinant laminin-521 (LN-521) and cellulose nanofibrils (CNF). Cell adhesion to LN-521-coated probes was remarkably influenced by cell viability, divalent cations, and integrin density in WA07 colonies, indicating that specific bonds between LN-521 and activated integrins play a significant role in the interactions between LN-521 and HepG2 and WA07 cells. In contrast, the interactions between CNF and cells were nonspecific and not influenced by cell viability or the presence of divalent cations. These results shed light on the underlying mechanisms of cell adhesion, with direct impact on cell culture and tissue engineering applications.

Single-layer films from cellulose nanofibrils on a plastic support were coated with sol–gel coated with inorganic–organic copolymers (ORMOCER®s), consisting of inorganic Si–O–Si-based networks combined with ceramic (Al–O– and Zr–O–) groups and special organic fluoroalkyl chain containing functional groups. Sol–gel coatings decreased the surface hydrophilicity and water vapor transmission rate. The water contact angle of uncoated films was 24°, indicating high affinity between water and the cellulose nanofibrils. All sol–gel coatings tested increased the surface hydrophobicity with the contact angles ranging between 54° and 102°. The water vapor transmission rates varied between 230 and 410 g/m2/day. With UV curable highly organically crosslinked coating, the water vapor transmission rate was decreased by 77% as compared to uncoated film. The uncoated film had oxygen transmission rates of 0.7 and 107 cc/m2/day at 50% and 80% RH, respectively. At high humidity conditions, the films tended to swell, thus allowing permeation to increase. Sol–gel coatings significantly improved the oxygen barrier properties especially at 80% RH. The transmission rates varied between 0.4 and 0.5 cc/m2/day (50% RH) and between 51 and 86 cc/m2/day (80% RH).

Bilayer actuators, traditionally consisting of two laminated materials, are the most common types of soft or hybrid actuators. Herein, a nanomaterial‐based organic–inorganic humidity‐sensitive bilayer actuator composed of TEMPO‐oxidized cellulose nanofibrils (TCNF‐Na+) and reduced graphene oxide (rGO) sheets is presented. The hybrid actuator displays a large humidity‐driven locomotion with an atypical fast unbending. Cationic exchange of the anionically charged TCNF‐Na+ and control of the layer thickness is used to tune and dictate the locomotion and actuator's response to humidity variations. Assembly of a self‐oscillating electrical circuit, that includes a conductive rGO layer, displays autonomous on‐and‐off lighting in response to actuation‐driven alternating electrical heating.

This review outlines the present state and recent progress in the area of lignin-containing cellulose nanofibrils (LCNFs), an emerging family of green cellulose nanomaterials. Different types of LCNF raw materials are described, with main focus on wood-based raw materials, and the properties of the resulting LCNFs are compared. Common problems faced in industrial utilization of CNFs are discussed in the light of potential improvements from LCNFs, covering areas such as chemical and energy consumption, dewatering and redispersibility. Out of the potential applications, barrier films, emulsions and nanocomposites are considered.

Cellulose aerogel is an advanced thermal insulating biomaterial. However, the application of cellulose aerogel in thermal insulation still faces critical problems, for instance, the relatively low strength and large pore size without Knudsen effect. In this study, a silica areogel made from olivine silica rather than traditional tetraethoxysilane or water glass is employed to synthesize silica-cellulose composite aerogel applying a facile one-pot synthesis method. The silica aerogel nanoparticles are formed inside the cellulose nanofibrils by using sol-gel method and freeze-drying. The developed silica-cellulose composite aerogel has an obviosuly lowered thermal conductivity and is significantly stronger compared to plain cellulose aerogel. The microstructure of silica-cellulose aerogel was characterized by SEM, TGA, FTIR and N 2 physisorption tests. The developed silica-cellulose aerogel had a bulk density of 0.055 ~ 0.06 g/cm 3, compressive strength of 95.4 kPa, surface area of 900 m 2/g and thermal conductivity of 0.023 W/(m·K). The thermal stability of the composite aerogel was also improved and showed the higher cellulose decomposition temperature. Furthermore, the composite aerogel is modified by trimethylchlorosilane making it hydrophobic, reaching a water contact angle of ~ 140°, enhancing its volumetric and thermo-phycial stability when applied in a humid environment. In conclusion, the resulting green silica-cellulose aerogel is a promising candidate for utilization as a high performance insulation material.

A “waste-valorization” approach was developed to transform recalcitrant hydrolysis lignin (HL) from second-generationbioethanol productioninto multifunctional bio-based products. The hydrolysis lignin (HL) was extracted with aqueousacetone, yielding two fractions enriched in lignin and cellulose, respectively. The soluble hydrolysis lignin (SHL) was converted into anionic and cationic colloidal lignin particles (CLPs and c-CLPs). The insoluble cellulose-rich fraction was transformed intolignocellulosicnanofibrils that were further combined with CLPs or c-CLPs to obtainnanocomposite filmswithtailored mechanical properties,oxygen permeabilityand antioxidant properties. To enable prospective applications of lignin in nanocomposite films and beyond, CLPs and c-CLPs were also produced from a soda lignin (SL) and the influence of the lignin type on the particle size and ecotoxicity was evaluated. Finally, the carbon footprint of the entire process from hydrolysis lignin to films was assessed and an integration to industrial scale was considered to reduce the energy consumption. While most previous work utilizes purified lignin and pristine and often purified cellulose fibers to produce nanomaterials, this work provides aproof of conceptfor utilizing the recalcitrant lignin-rich side stream of thebioethanolprocess as raw material for functional nanomaterials and renewable composites.

This study covers a green method to prepare hybrid lignocellulosic nanopapers by combining wood nanofibres (WNFs) and cellulose nanofibres (CNFs). The WNFs and CNFs behave synergistically to compensate for the drawbacks of each other resulting in enhanced hybrid nanopapers. The draining time of hybrid nanopapers was improved by up to 75% over CNF nanopaper, and the mechanical properties, modulus, strength and elongation, were respectively improved up to 35%, 90% and 180% over WNF nanopaper. Additionally, the water resistance of hybrid nanopapers was considerably improved with a water contact angle of 95°; the neat CNF nanopaper had a contact angle of 52°. The morphology of nanopapers, studied by electron microscopy, indicated that lignin acts as a matrix, which binds the nanofibres together and makes them impervious to external environmental factors, such as high humidity. The reported hybrid nanopapers are 100% bio-based, prepared by a simple and environmentally friendly processing route. Reported hybrid nanopapers can be used in novel applications such as gas barrier membranes and printable electronics.

Biomaterials of different nature have been and are widely studied for various biomedical applications. In many cases, biomaterial assemblies are designed to mimic biological systems. Although biomaterials have been thoroughly characterized in many aspects, not much quantitative information on the molecular level interactions between different biomaterials is available. That information is very important, on the one hand, to understand the properties of biological systems and, on the other hand, to develop new composite biomaterials for special applications. This work presents a systematic, quantitative analysis of self- and cross-interactions between films of collagen I (Col I), collagen IV (Col IV), laminin (LN-521), and cellulose nanofibrils (CNF), that is, biomaterials of different nature and structure that either exist in biological systems (e.g., extracellular matrices) or have shown potential for 3D cell culture and tissue engineering. Direct surface forces and adhesion between biomaterials-coated spherical micro-particles and flat substrates were measured in phosphate-buffered saline using an atomic force microscope and the colloidal probe technique. Different methods (Langmuir-Schaefer deposition, spin-coating, or adsorption) were applied to completely coat the flat substrates and the spherical micro particles with homogeneous biomaterial films. The adhesion between biomaterials films increased with the time that the films were kept in contact. The strongest adhesion was observed between Col IV films, and between Col IV and LN-521 films after 30 s contact time. In contrast, low adhesion was measured between CNF films, as well as between CNF and LN-521 films. Nevertheless, a good adhesion between CNF and collagen films (especially Col I) was observed. These results increase our understanding of the structure of biological systems and can support the design of new matrices or scaffolds where different biomaterials are combined for diverse biological or medical applications.

When studying the properties of cellulose nanofibrils (CNF) enriched fiber products, it is essential to be able to determine the retention and the spatial distribution of the CNF inside the end-product. That is, to determine how much and where the CNF has been attached. As the CNF and cellulose fibers share the same density and chemical composition, labeling of the CNF is required to distinguish them from each other. In this work, we have applied iron and iron-cobalt -labeling. Labeling with iron is more desirable because of the carcinogenic and toxic properties of cobalt chloride. The benefits of our labeling method are the possibility to determine the retention of the labeled nanocellulose using inductively coupled plasma optical emission spectroscopy (ICP-OES), and to define the spatial distribution using X-ray micro-computed tomographic (XμCT). With XμCT we were able to measure fairly large samples (2 cm × 5 cm × 5 cm). Our study found that the retention of iron-labeled CNF was about 95 % and that of iron-cobalt labeled CNF was 84–94 %. Labeling of CNF improves the contrast of X-ray images. Labeled CNF is attached to fiber network also in the inner structures of the sample. Furthermore, when making thick porous structures using cationic starch, there might be agglomerates in the sample that cannot be visually detected by looking the sample.

Made available in DSpace on 2021-06-25T11:11:12Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-04-15 Natural Sciences and Engineering Research Council of Canada Ontario Research Foundation Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) In this study, for the first time, a flexible substrate made from nanofibrillated cellulose in slurry form was fabricated using a hydrophobic polymer base. Previous studies practiced energy-intensive dry cellulose nanofiber dispersion to produce olefin-based composites: ecological and economic viability and industrial practicability are often neglected due to lack of innovation in cleaner production processes. In this context, a low-energy process, which is economically attractive and free of harmful organic solvents, was developed to achieve homogeneous distribution of nanofibrillated cellulose (NFC) in high-density polyethylene (HDPE). The dual interfacial role of the ethylene vinyl alcohol copolymer (EVAL – 48 mol% ethylene content) enhanced interfacial adhesion through the formation of nanobridges between HDPE and NFC. This method led to well-dispersed NFC in the HDPE, at 5 wt% NFC concentration, without the need of any chemical modification, solvent exchange or freeze-drying of NFC. The low interfacial tension between HDPE and EVAL and the presence of NFC in the ternary system led to enhanced dispersion during melt-mixing. Improvement in mechanical properties was achieved, with a 22% and 98% increase in the tensile strength and Young's modulus, respectively, without significantly compromising thermal stability and barrier properties. The results shown in this study indicate a significant potential to replace synthetic and costly reinforcement additives while making nanofiber-reinforced flexible composites more sustainable and mechanically robust. In this context, a paradigm shift from fossil-based production technology to a cleaner production strategy such as those exemplified in this study will help achieve a circular production economy concept without hindering functionalities. Centre for Biocomposites and Biomaterials Processing John H. Daniels Faculty of Architecture Landscape and Design University of Toronto, Toronto Department of Mechanical and Industrial Engineering University of Toronto, Toronto College of Agricultural Sciences São Paulo State University (Unesp), Botucatu College of Mechanical and Electrical Engineering Beijing University of Chemical Technology TOTAL American Services Inc. College of Agricultural Sciences São Paulo State University (Unesp), Botucatu CNPq: 202275/2015–9

openaire: EC/H2020/788489/EU//BioELCell The authors acknowledge support from the Canada Excellence Research Chair initiative, the Canada Foundation for Innovation (CFI), and the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (ERC Advanced Grant Agreement 788489, BioElCell). This material was also partly based on work supported by the National Institute of Food and Agriculture, US Department of Agriculture (USDA), Massachusetts Agricultural Experiment Station (project number 831), and USDA Agriculture and Food Research Initiative grants (2016-08782). Publisher Copyright: © 2021 Annual Reviews Inc.. All rights reserved. Copyright: Copyright 2021 Elsevier B.V., All rights reserved. In this article, the application of nanocelluloses, especially cellulose nanofibrils and cellulose nanocrystals, as functional ingredients in foods is reviewed. These ingredients offer a sustainable and economic source of natural plant-based nanoparticles. Nanocelluloses are particularly suitable for altering the physicochemical, sensory, and nutritional properties of foods because of their ability to create novel structures. For instance, they can adsorb to air-water or oil-water interfaces and stabilize foams or emulsions, self-assemble in aqueous solutions to form gel networks, and act as fillers or fat replacers. The functionality of nanocelluloses can be extended by chemical functionalization of their surfaces or by using them in combination with other natural food ingredients, such as biosurfactants or biopolymers. As a result, it is possible to create stimuli-responsive, tailorable, and/or active functional biomaterials suitable for a range of foodapplications. In this article, we describe the chemistry, structure, and physicochemical properties of cellulose as well as their relevance for the application of nanocelluloses as functional ingredients in foods. Special emphasis is given to their use as particle stabilizers in Pickering emulsions, but we also discuss their potential application for creating innovative biomaterials with novel functional attributes, such as edible films and packaging. Finally, some of the challenges associated with using nanocelluloses in foods are critically evaluated, including their potential safety and consumer acceptance.

openaire: EC/H2020/788489/EU//BioELCell Funding Information: This work was supported by the Canada Excellence Research Chair initiative, the European Research Council under the European Union’s Horizon 2020 research and innovation program (ERC Advanced grant no. 788489, “BioElCell”), and the Canada Foundation for Innovation (CFI). This work was also part of the Academy of Finland’s Flagship Programme (Competence Center for Materials Bioeconomy, FinnCERES) under project no. 318890 and 318891. Publisher Copyright: © Copyright: Copyright 2021 Elsevier B.V., All rights reserved. We consider the variables relevant to adsorption of renewable nanoparticles and stabilization of multiphase systems, including the particle's hydrophilicity, electrostatic charge, axial aspect, and entanglement. Exploiting the complexation of two oppositely charged nanopolysaccharides, cellulose nanofibrils (CNFs) and nanochitin (NCh), we prepared CNF/NCh aqueous suspensions and identified the conditions for charge balance (turbidity and electrophoretic mobility titration). By adjusting the composition of CNF/NCh complexes, below and above net neutrality conditions, we produced sunflower oil-in-water Pickering emulsions with adjustable droplet diameters and stability against creaming and oiling-off. The adsorption of CNF/NCh complexes at the oil/water interface occurred with simultaneous partitioning (accumulation) of the CNF on the surface of the droplets in net negative or positive systems (below and above stochiometric charge balance relative to NCh). We further show that the morphology of the droplets andsize distribution were preserved during storage for at least 6 months under ambient conditions. This long-term stability was held with a remarkable tolerance to changes in pH (e.g., 3-11) and ionic strength (e.g., 100-500 mM). The mechanism explaining these observations relates to the adsorption of the CNF in the complexes, counteracting the charge losses resulting from the deprotonation of NCh or charge screening. Overall, CNF/NCh complexes and the respective interfacial nanoparticle exchange greatly extend the conditions, favoring highly stable, green Pickering emulsions that offer potential in applications relevant to foodstuff, pharmaceutical, and cosmetic formulations.

Bio-based aerogels containing cellulose nanofibrils (CNFs) are promising materials due to the inherent physical properties of CNF. The high affinity of cellulose to plant hemicelluloses (xyloglucan, xylan, pectin) is also an opportunity to develop biomaterials with new properties. Here, we prepared aerogels from gelled dispersions of CNFs and xyloglucan (XG) at different ratios by using a freeze-casting procedure in unidirectional (UD) and non-directional (ND) manners. As showed by rheology analysis, CNF and CNF/XG dispersions behave as true gels. We investigated the impact of the freezing procedure and the gel&rsquo, s composition on the microstructure and the water absorption properties. The introduction of XG greatly affects the microstructure of the aerogel from lamellar to cellular morphology. Bio-based aerogels showed high water absorption capacity with shape recovery after compression. The relation between morphology and aerogel compositions is discussed.

This work informs on the green synthesis of a novel adsorbent and its adsorption capacity. The adsorbent was synthesized by the combination of iron nanoparticles and cellulose nanofibers (FeNPs/NFCs). Cellulose nanofibers (NFCs) were obtained from Moringa (Moringa oleifera Lam.) by a pulping Kraft process, acid hydrolysis, and ultrasonic methods. The adsorption method has advantages such as high heavy metal removal in water treatment. Therefore, cadmium (Cd) and lead (Pb) adsorption with FeNP/NFC from aqueous solutions in batch systems was investigated. The kinetic, isotherm, and thermodynamic parameters, as well as the adsorption capacities of FeNP/NFC in each system at different temperatures, were evaluated. The adsorption kinetic data were fitted to mathematical models, so the pseudo-second-order kinetic model described both Cd and Pb. The kinetic rate constant (K2), was higher for Cd than for Pb, indicating that the metal adsorption was very fast. The adsorption isotherm data were best described by the Langmuir&ndash, Freundlich model for Pb multilayer adsorption. The Langmuir model described Cd monolayer sorption. However, experimental maximum adsorption capacities (qe exp) for Cd (&gt, 12 mg/g) were lower than those for Pb (&gt, 80 mg/g). In conclusion, iron nanoparticles on the FeNP/NFC composite improved Cd and Pb selectivity during adsorption processes, indicating the process&rsquo, spontaneous and exothermic nature.

In this work fully biomass-based hydrogels were developed using a naturally occurring vegetable hydrocolloid co-mingled with wood-derived nanocellulose fibrils. Two distinct types of hydrocolloids have been considered: a seaweed-derived biopolymer (alginate) and a plant-derived biopolymer (pectin). To attain nano-structured binary hydrogels, surface-functionalized cellulose nanofibrils (CNFs) bearing carboxyl groups were employed. This study addresses a non-conventional approach of physical gelation that takes place in acidic conditions (pH

Biohybrid colloids were fabricated based on electrostatic complexation between anionic TEMPO-oxidized cellulose nanofibrils (TO-CNF) and cationic hen egg white lysozyme (HEWL). By altering the loading of HEWL, physical colloidal complexes can be obtained at a relatively low concentration of TO-CNF (0.1 wt%). At neutral pH, increasing the HEWL loading induces an increase in charge screening, as probed by zeta-potential, resulting in enhanced TO-CNF aggregation and colloidal gel formation. Systematic rheological testing shows that mechanical reinforcement of the prepared biohybrid gels is easily achieved by increasing the loading of HEWL. However, due to the relatively weak nature of electrostatic complexation, the formed colloidal gels exhibit partial destruction when subjected to cyclic shear stresses. Still, they resist thermo-cycling up to 90 °C. Finally, the pH responsiveness of the colloidal complex gels was demonstrated by adjusting pH to above and below the isoelectric point of HEWL, representing a facile mechanism to tune the gelation of TO-CNF/HEWL complexes. This work highlights the potential of using electrostatic complexation between HEWL and TO-CNF to form hybrid colloids, and demonstrates the tunability of the colloidal morphology and rheology by adjusting the ratio between the two components and the pH., Carbohydrate Polymers, 251, ISSN:0144-8617, ISSN:1879-1344

This paper reports on the effect of cellulose nanofibrils (CNFs) on the fresh-state properties of alkali activated ground granulated blast-furnace slag (GGBS). Surface functionalized (oxidized) CNFs were added to alkali activated GGBS water suspensions (hydraulic pastes). The rheological behaviour of the pastes was compared with OPC and interpreted based on the CNF-mineral surface interaction, and on the CNF-water interaction and swelling. The water dispersion of CNFs with different surface functionalization degrees resulted in gels of different viscosity and yield stress, due to their different hydrophilicity and water adsorption properties. On increasing the CNFs surface oxidation degree, the viscosity of the CNF water dispersion decreases and the CNF water adsorption increases, while the viscosity of fresh pastes increases because of the reduced amount of available mixing water. In the hardened state, the hydraulic pastes show differences in mechanical strength related to the type and the amount of CNF influencing the porosity of the matrix as evidenced by the microstructural investigation performed by X-ray microtomography. The presence of higher amounts of CNFs induces the formation of porous agglomerates that may act as stress concentrators due to the swelling ability of nanofibrils.

Made available in DSpace on 2021-06-25T11:13:10Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-15 Natural Sciences and Engineering Research Council of Canada Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) Photoresponsive functionalized nanofilms were prepared via radical polymerization of carbazole units on a nanofibrillated cellulose (NFC) backbone via one-pot procedure. Herein, NFC was functionalized with active carbazole units as pendant organic moieties. The nanofilms were characterized by UV–vis and fluorescence spectroscopy, Fourier transformed infrared (FTIR) and Raman spectroscopy, 13C NMR and proton NMR spectra, contact angle analysis, mechanical testing, and scanning electron microscopy (SEM). The fabricated nanofilms exhibited large tensile strength (∼110 MPa), higher hydrophobicity and luminescence activity. The results indicated that the prepared optically active nanofilms present potential applications in the fields of flexible organic light emitting devices. Centre for Biocomposites and Biomaterials Processing John H. Daniels Faculty of Architecture Landscape and Design University of Toronto Department of Mechanical and Industrial Engineering University of Toronto Department of Mechanical and Aerospace Engineering Carleton University College of Agricultural Sciences São Paulo State University (Unesp) TOTAL American Services Inc. College of Agricultural Sciences São Paulo State University (Unesp) CNPq: 202275/2015-9

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.

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.

International audience

Cellulose nanofibrils (CNF) is considered as an inexhaustible precursor to produce antibacterial materials, such as antibacterial hydrogel, antibacterial paper, and antibacterial film. However, the poor antimicrobial property of neat CNF required it should be coupled with an antibacterial ingredient. Herein, biocompatible Au nanoclusters (AuNCs) were synthesized and added into the CNF dispersion to prepare a novel antibacterial film (AuNCs@CNF film). The effects of addition of AuNCs with different amount on the morphology and physicochemical properties of AuNCs@CNF films were characterized using atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray diffraction (XRD), FTIR (Fourier-transform infrared), light transmittance spectra, and thermogravimetric analysis (TGA). The results showed that AuNCs did not affect the nano-structural features of the CNF film and its basic structures, but could greatly increase the hydrophilicity, the flexibility and the thermal stability of CNF film, which might improve its application in antimicrobial wound-healing dressing. The prepared AuNCs@CNF films demonstrated high antibacterial properties toward Escherichia coli (E. coli) and Streptococcus mutans (S. mutans) both in vitro and in vivo, which can prohibit their growths and promote the healing of bacteria-infected wound, respectively. Thus, the prepared AuNCs@CNF film with great antibacterial properties could be applicable in biomedical field.

Designing lightweight nanostructured aerogels for high-performance electromagnetic interference (EMI) shielding is crucial yet challenging. Ultrathin cellulose nanofibrils (CNFs) are employed for assisting in building ultralow-density, robust, and highly flexible transition metal carbides and nitrides (MXenes) aerogels with oriented biomimetic cell walls. A significant influence of the angles between oriented cell walls and the incident EM wave electric field direction on the EMI shielding performance is revealed, providing an intriguing microstructure design strategy. MXene "bricks" bonded by CNF "mortars" of the nacre-like cell walls induce high mechanical strength, electrical conductivity, and interfacial polarization, yielding the resultant MXene/CNF aerogels an ultrahigh EMI shielding performance. The EMI shielding effectiveness (SE) of the aerogels reaches 74.6 or 35.5 dB at a density of merely 8.0 or 1.5 mg cm(-3), respectively. The normalized surface specific SE is up to 189 400 dB cm(2) g(-1), significantly exceeding that of other EMI shielding materials reported so far., Advanced Science, 7 (15), ISSN:2198-3844

The use of advanced and eco-friendly materials has become a trend in the field of food packaging. Cellulose nanofibrils (CNFs) were prepared from bleached bagasse pulp board by a mechanical grinding method and were used to enhance the properties of a chitosan/oregano essential oil (OEO) biocomposite packaging film. The growth inhibition rate of the developed films with 2% (w/w) OEO against E. coli and L. monocytogenes reached 99%. With the increased levels of added CNFs, the fibrous network structure of the films became more obvious, as was determined by SEM and the formation of strong hydrogen bonds between CNFs and chitosan was observed in FTIR spectra, while the XRD pattern suggested that the strength of diffraction peaks and crystallinity of the films slightly increased. The addition of 20% CNFs contributed to an oxygen-transmission rate reduction of 5.96 cc/m2&middot, day and water vapor transmission rate reduction of 741.49 g/m2&middot, day. However, the increase in CNFs contents did not significantly improve the barrier properties of the film. The addition of 60% CNFs significantly improved the barrier properties of the film to light and exhibited the lowest light transmittance (28.53%) at 600 nm. Addition of CNFs to the chitosan/OEO film significantly improved tensile strength and the addition of 60% CNFs contributed to an increase of 16.80 MPa in tensile strength. The developed chitosan/oregano essential oil/CNFs biocomposite film with favorable properties and antibacterial activity can be used as a green, functional material in the food-packaging field. It has the potential to improve food quality and extend food shelf life.

The present work intends to study the variations in the rheological properties and aggregation behaviour of TEMPO-oxidised cellulose nanofibrils (CNF) aqueous suspensions, as a function of changes in concentration and systematic changes in the pH, by addition of acids with different anions. It was found that CNF suspensions form strong gels at mass fractions higher than 0.35 % and the gel point is ca. 0.18 %. On the other hand, aggregation is enhanced at acidic pH conditions due to lower charge repulsion among fibrils, leading to an increase of the suspension viscosity. However, distinct rheological behaviours were presented by CNF suspensions as different acids were applied. It was found that phosphate ions resulted in significant aggregation leading to formation of particles of large size and very strong gels, at pH 2.3; distinctly, the presence of acetate ions resulted in lower aggregation, lower particle size and weaker gels, at the same pH value. The present research was supported by the R&D Project “FILCNF- New generation of composite films of cellulose nanofibrils with mineral particles as high strength materials with gas barrier properties” (PTDC/QUI-OUT/31884/2017, CENTRO 01-0145-FEDER-031884) and Strategic Research Centre Project,UIDB00102/2020, both funded by the Fundação para a Ciência e Tecnologia (FCT). A. F. Lourenço also acknowledges Fundação para a Ciência e Tecnologia for the PhD grant (SFRH/BDE /108095/2015). CENTRO-01-0145-FEDER-031884 info:eu-repo/semantics/publishedVersion

This work aimed in preparing nanocelluloses from a unique source of cellulose, viz. phormium (Phormiun tenax) fibers, by different techniques; and evaluate their physicochemical and structural properties. It was possible to obtain cellulose nanofibrils with different sizes (diameter, length and aspect ratio), morphology, crystallinity and surface charge by mechanical disintegration of bleached and refined phormium fibers previously modified or not with enzymatic and oxidative treatments with endoglucanases and 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), respectively. But it was not possible to prepare nanocrystals by acid hydrolysis, even when trying to modify the reaction conditions, possibly due at least partially to the presence of residual hemicelluloses and lignin. Process efficiency seemed to depend variably on the initial state of phormium (Phormiun tenax) fibers and the presence of other components such as lignin and hemicelluloses. These nanofibers could be used for different purposes in different areas according to their physicochemical characteristics., Centro de Investigación y Desarrollo en Criotecnología de Alimentos

Review The need for reaching environmental sustainability encourages research on new cellulosebased materials for a broad range of applications across many sectors of industry. Cellulosic nanomaterials obtained from different sources and with different functionalization are being developed with the purpose of its use in many applications, in pure and composite forms, from consumer products to pharmaceutics and healthcare products. Based on previous knowledge about the possible adverse health effects of other nanomaterials with high aspect ratio and biopersistency in body fluids, e.g., carbon nanotubes, it is expected that the nanometric size of nanocellulose will increase its toxicity as compared to that of bulk cellulose. Several toxicological studies have been performed, in vitro or in vivo, with the aim of predicting the health effects caused by exposure to nanocellulose. Ultimately, their goal is to reduce the risk to humans associated with unintentional environmental or occupational exposure, and the design of safe nanocellulose materials to be used, e.g., as carriers for drug delivery or other biomedical applications, as in wound dressing materials. This review intends to identify the toxicological effects that are elicited by nanocelluloses produced through a topdown approach from vegetal biomass, namely, cellulose nanocrystals and nanofibrils, and relate them with the physicochemical characteristics of nanocellulose. For this purpose, the article provides: (i) a brief review of the types and applications of cellulose nanomaterials; (ii) a comprehensive review of the literature reporting their biological impact, alongside to their specific physicochemical characteristics, in order to draw conclusions about their effects on human health. The authors acknowledge CYTED network NANOCELIA (Transferencia Tecnolo´gica sobre aplicaciones de nanocelulosa en iberoame´rica). The work was funded by FCT/MCTES, Project ToxApp4NanoCELFI (PTDC/ SAU-PUB/32587/2017) through national funds (PIDDAC), and co-funded by ToxOmics – Center for Toxicogenomics and Human Health (UID/BIM/00009/2013). Sara Teixeira is acknowledged for the binucleated cells photo. info:eu-repo/semantics/publishedVersion

Novel and unique applications of nanocellulose are largely driven by the functional attributes governed by its structural and physicochemical features including excellent mechanical properties and biocompatibility. In recent years, thousands of groundbreaking works have helped in the development of targeted functional nanocellulose for conductive, optical, luminescent materials, and other applications. The growing demand for sustainable and renewable materials has led to the rapid development of greener methods for the design and fabrication of high-performance green nanomaterials with multiple features, and consequently new challenges and opportunities. The present review article discusses historical developments, various fabrication and functionalization methods, the current stage, and the prospects of flexible energy and hybrid electronics based on nanocellulose.

International audience; Rheological properties of hydrogels composed of TEMPO-oxidised cellulose nanofibrils (OCNF)-starch in the presence of cationic surfactants were investigated. The cationic surfactants dodecyltrimethylammonium bromide (DTAB) and cetyltrimethylammonium bromide (CTAB) were used to trigger gelation of OCNF at around 5mM surfactant. As OCNF and DTAB/CTAB are oppositely charged, an electrostatic attraction is suggested to explain the gelation mechanism. OCNF (1 wt%) and soluble starch (0.5 and 1 wt%) were blended to prepare hydrogels, where the addition of starch to the OCNF resulted in a higher storage modulus. Starch polymers were suggested to form networks with cellulose nanofibrils. The stiffness and viscosity of OCNF-Starch hydrogels were enhanced further by the addition of cationic surfactants (5mM of DTAB/CTAB). ζ -potential and amylose-iodine complex analyses were also conducted to confirm surface charge and interaction of OCNF-starch-surfactant in order to provide an in-depth understanding of the surfactant-induced gel networks.

Here we demonstrate a straightforward vapour-assisted roll-to-roll nanoimprinting lithography (R2RVANIL) patterning method to biobased nanocellulosic films with the aim to fabricate microstructured films with diffraction effect. In the R2RVANIL technique a roll with pillar structures is softly pressed against nanocellulose film in the presence of hot water vapour replicating the pattern onto the film. The printed pillar structures are compared with the structures produced using traditional thermal R2RNIL. The manufacturing method is demonstrated using optically transparent TEMPO-oxidised cellulose nanofibrils (TEMPO CNF). TEMPO CNF films possess high tensile strength and modulus whereas the tensile strain is low, they are very hygroscopic - a property which improves material processing at elevated humidities, thus overcoming a lack of a clear softening point. In this context, the water molecules are acting as plasticising molecules thereby softening the relative brittle nanocellulose film structures. Patterned pillars were achieved due to the swelling and softening of the film which was contacted with moist air. R2RVANIL method appears to be more gentle and surface properties such as roughness are different from the ones achieved via conventional thermal NIL method. The diffraction grating is demonstrated using laser beam compared to calculated diffraction patterns. Water vapour assisted patterning methods are beneficial, for example, in the future optics and electronics where films cannot be processed under high pressure and, on the other hand, high production volumes are needed.

Nanocelluloses are being explored and produced at an impressively increasing pace. Due to their good characteristics as reinforcement agent, their application in the most diverse fields has proven to be very beneficial. Their use in papermaking has been investigated in several studies, but the industrial implementation is still in a preliminary stage. In the present study, the influence of nanocelluloses, produced by four different treatments (mechanical, enzymatic hydrolysis, TEMPO-mediated oxidation and carboxymethylation) in the properties of filler-containing laboratory handsheets was assessed. Furthermore, five series produced with different additives, among internal strength and sizing agents as well as a retention agent, allowed to investigate the interactions between the common additives used in paper production and nanocelluloses. It was found that the different properties of the studied nanocelluloses led to very different interactions with the paper components. In this sense, by properly selecting the furnish to use (in terms of nanocellulose typology and presence or absence of each additive), high improvements of filler retention and dry and wet--web strength, as well as reduced surface roughness and water penetration, could be achieved.

Nanocelluloses have emerged as a catalogue of renewable nanomaterials for bioink formulation in service of 3D bioprinting, thanks to their structural similarity to extracellular matrices and excellent biocompatibility of supporting crucial cellular activities. From a material scientist’s viewpoint, this mini-review presents the key research aspects of the development of the nanocellulose-based bioinks in 3D (bio)printing. The nanomaterial properties of various types of nanocelluloses, including bacterial nanocellulose, cellulose nanofibers, and cellulose nanocrystals, are reviewed with respect to their origins and preparation methods. Different cross-linking strategies to integrate into multicomponent nanocellulose-based bioinks are discussed in terms of regulating ink fidelity in direct ink writing as well as tuning the mechanical stiffness as a bioactive cue in the printed hydrogel construct. Furthermore, the impact of surface charge and functional groups on nanocellulose surface on the crucial cellular activities (e.g., cell survival, attachment, and proliferation) is discussed with the cell–matrix interactions in focus. Aiming at a sustainable and cost-effective alternative for end-users in biomedical and pharmaceutical fields, challenging aspects such as biodegradability and potential nanotoxicity of nanocelluloses call for more fundamental comprehension of the cell–matrix interactions and further validation in in vivo models.

This study explored the development and characterization of laminated wallboard panels using renewable materials for building applications. The panels are based on cellulose nanofibrils (CNFs) as a binder and wood particles. Other additives included FiberLeanTM (microfibrillated cellulose/calcium carbonate composite), starch and fire retardant (boric acid/borax). These panels are also intended to address the environmental concerns of commercial gypsum boards. The manufacturing of the panels is via a wet-based process, hence no initial drying was required to remove the water from the CNF. It was found that the dosage of CNF (and/or FiberLeanTM) binder and the addition of starch had the largest impact upon the quality of the final product. The addition of starch was found more favorable in the presence of FiberLeanTM. The fire retardancy was induced by adding boric acid/borax (1:1). The burning test revealed that the panels treated with the fire retardant exhibited excellent burning properties comparable to that of gypsum board (inherently fire resistant). Interestingly, the addition of the boric acid/borax also appeared to increase the retention of starch in the system, leading to favorable mechanical properties.

An active ink composed of cellulose nanofibrils and silver nanowires was deposited on flexible and transparent polymer films using the bar coating process, achieving controlled thicknesses ranging from 200 nm up to 2 μm. For 350 nm thick coating on polyethylene terephthalate films, high transparency (75.6% transmittance) and strong reduction of bacterial growth equal to 89.3% and 100% was noted respectively against Gram-negative Escherichia Coli and Gram-positive Staphylococcus Aureus bacteria using AATCC contact active standard test. Retained antibacterial activity was found with films produced by reverse gravure roll-to-roll process, showing the promising capability of this antibacterial solution to be deployed industrially. Finally, the same ink was also deposited on polylactic acid substrate to investigate barrier properties: for 350 nm thick coating, a reduction of 49% of oxygen transmission rate (dry conditions) and 47% reduction of water vapor transmission rate was noted, proving the enhanced barrier properties of the coatings.

The surface initiated ring opening polymerization (SI-ROP) of cellulose nanofibers (CNF) with rac-Lactide under mild conditions using N,N-dimethyl aminopyridine (DMAP) was investigated. The influence of catalyst amount, monomer-to-initiator (cellulose surface -OH groups) ratio, temperature, and cellulose preconditioning (lyophilization vs solvent exchange) were studied to determine the best SI-ROP conditions, and to understand the effect of the parameters on grafting efficiency. The fibers modified after lyophilization had a PLA content comparable to those obtained with traditional metal catalysts (e.g. tin-(II)ethylhexanoate). Starting from a stable dispersion of CNF in dichloromethane obtained through solvent-exchange showed better results at low catalyst amounts. Furthermore, DMAP was readily removed from the products whereas metal catalysts can be hard to remove from the final material, potentially shortening the material lifespan and making it unfit for some applications. Therefore, the use of an easily removable and more efficient organocatalyst can be considered a good alternative to metal catalysts. ispartof: Carbohydrate Polymers vol:250 pages:1-8 ispartof: location:England status: published

International audience; Nanocomposites based on thermoplasticized starch filled with cellulose nanofibrils (CNFs) were produced in a single step by twin-screw extrusion of corn starch granules, glycerol as a plasticizer, and oxidized cellulose fibers. The objective was to demonstrate the possibility to produce CNFs in situ during the processing of the nanocomposite when a hydrophilic polymer matrix was used. For comparison purpose, nanocomposites were also prepared by extrusion of a previously prepared CNF suspension, corn starch granules and glycerol. The nanocomposites were characterized in terms of mechanical properties, morphology, crystallinity, and transparency. The nanocomposites prepared via in situ fibrillation displayed a higher strength than those produced by incorporating readily prepared CNFs. In addition, the transparency degree up to a 15 wt% CNF content was similar for the two processing routes, confirming the effective breakdown of pretreated cellulose fibers into CNFs during the extrusion process.

International audience; Natural structural materials frequently consist of multimaterial nanocomposites with complex superstructure giving rise to exceptional mechanical properties, but also commonly preventing access to their synthetic reproduction. Here we present the spin-assisted layer-by-layer assembly of anisotropic wood-inspired films composed of anionic cellulose nanofibrils and cationic poly(vinyl amine) possessing a tensile strength that exceeds that of the wood from which the fibers originate. The degree of orientation of the nanofibrils was studied by atomic force microscopy and depends strongly on the distance from the center of the spun surface. The nanofibrils are preferentially aligned in the direction of the shear flow, and consequently, the mechanical properties of such films differ substantially when measured parallel and perpendicular to the fibril orientation direction. For enabling a diversity of bioinspired applications including sensing, packaging, electronics, or optics, the preparation of nanocomposite materials and devices with anisotropic physical properties requires an extreme level of control over the positioning and alignment of nanoscale objects within the matrix material.

In this paper, anionic TEMPO-oxidized cellulose nanofibers (TO-CNFs) and cationic, partially deacetylated, chitin nanocrystals (ChNCs) were used to fabricate continuous composite filaments (TO-CNF/ChNC filament) with a straightforward and sustainable aqueous process based on the interfacial nanoparticle complexation (INC) of oppositely charged nano-constituents. In particular, the role of TO-CNF and ChNC concentrations in filament drawing and the effect of drawing speed on the mechanical properties of composite filaments were investigated. Moreover, conductive filaments were fabricated by mixing single walled carbon nanotubes (SWCNTs) with TO-CNF dispersion and further complexing with the ChNC aqueous suspension. A conductive filament with an electrical conductivity of 2056 S/m was obtained. However, the increase in the SWCNTs content reduced the mechanical properties of the formed filament compared to neat TO-CNF/ChNC filament. This study not only introduces a new nanoparticle candidate to prepare filaments based on INC method but also provides potential advanced and alternative green filament to be used as wearable electronics in biomedical area.

Colloidal dispersions of cellulose nanofibrils (CNFs) are viable alternatives to cellulose II dissolutions used for filament spinning. The porosity and water vapor affinity of CNF filaments make them suitable for controlled breathability. However, many textile applications also require water repellence. Here, we investigated the effects of postmodification of wet-spun CNF filaments via chemical vapor deposition (CVD). Two organosilanes with different numbers of methyl substituents were considered. Various surface structures were achieved, either as continuous, homogeneous coating layers or as three-dimensional, hairy-like assemblies. Such surface features reduced the surface energy, which significantly affected the interactions with water. Filaments with water contact angles of up to 116° were obtained, and surface energy measurements indicated the possibility of developing amphiphobicity. Dynamic vapor sorption and full immersion experiments were carried out to inquire about the interactions with water, whether in the liquid or gas forms. Mechanical tests revealed that the wet strength of the modified filaments were almost 3 times higher than that of the unmodified precursors. The hydrolytic and mechanical stabilities of the adsorbed layers were also revealed. Overall, our results shed light on the transformation of aqueous dispersions of CNFs into filaments that are suited for controlled interactions with water via concurrent hydrolysis and condensation reactions in CVD, while maintaining the moisture buffering capacity and breathability of related structures.

Population growth coupled with significant pressure for clean agricultural practices puts a heavy burden on conventional crop treatments that target high yields with minimal cropland expansion. Optimization of fertilization systems is required as part of the solutions to current megatrends. Herein, we present a sustainable strategy to achieve controlled release formulations for nitrogen fertilization. Specifically, we used interfacial engineering to design alginate-based matrices that incorporated biogenic silica particles to achieve increased interfacial area for dynamic entrapment and release of ammonium nitrate. The incorporation of biogenic silica in the alginate matrix provided a porous architecture spanning length scales from the micro- (within particles) to the macrosize (within the polymeric matrix) levels, leading to tunable patterns of nitrogen release. Alginate–biogenic silica granules approached the European requirements of “slow-release” compositions. At optimized silica content, 15% of the n...

openaire: EC/H2020/788489/EU//BioELCell The shear and extensional rheology of aqueous suspensions of cellulose nanofibrils (CNF) were investigated under dynamic and steady flow fields. The results were compared to those for two biopolymer solutions, cellulose acetate, CA, and guar gum, GG. Wet-spinning experiments were conducted for each system and the outcome related to the respective rheological profile. The spinnability of the system correlated with strong Newtonian and viscous responses under shear as well as long breakup time in capillary breakup experiments. CA solution was the most spinnable, also displaying the strongest Newtonian liquid behavior and the longest capillary breakup time. In contrast, the most shear-thinning and elastic CNF suspension showed instant capillary breakup and was considerably less spinnable. This is due to the limited entanglement between the rigid cellulose fibrils. In order to enable continuous wet-spinning of CNF without filament breakup, GG and CA were used as carrier components in coaxial spinning. The shear and extensional rheology of the system is discussed considering both as supporting polymers.

Curdlan based cryogels were prepared and tested for their structural and thermal properties by using field emission scanning electron microscopy and thermogravimetric analysis, respectively. Volume shrinkage, mechanical performance, swelling, solubility and density were accessed as a function of composition, which included cellulose nanofibrils (CNF) and polyethylene oxide (PEO). PEO/CURD and PEO/CURD/CNF cryogels exhibited porous and layered structures. The addition of CNF significantly improved the in-vitro release of a nonsteroidal anti-inflammatory drug (diclofenac sodium), which is a promising alternative to current non-biodegradable systems.

The authors would like to acknowledge funding support by the Academy of Finland funding No.13307485 (3D Biomat.), 327248 (ValueBiomat), and 327865 (Bioeconomy). This work made use of the facilities of Aalto University's Nanomicroscopy Center. The authors also would like to acknowledge the discussions with Dr. Janika Lehtonen and Dr. Arun Teotia. Direct-ink-writing (DIW) of hydrogels has become an attractive research area due to its capability to fabricate intricate, complex, and highly customizable structures at ambient conditions for various applications, including biomedical purposes. In the current study, cellulose nanofibrils reinforced aloe vera bio-hydrogels were utilized to develop 3D geometries through the DIW technique. The hydrogels revealed excellent viscoelastic properties enabled extruding thin filaments through a nozzle with a diameter of 630 μm. Accordingly, the lattice structures were printed precisely with a suitable resolution. The 3D-printed structures demonstrated significant wet stability due to the high aspect ratio of the nano- and microfibrils cellulose, reinforced the hydrogels, and protected the shape from extensive shrinkage upon drying. Furthermore, all printed samples had a porosity higher than 80% and a high-water uptake capacity of up to 46 g/g. Altogether, these fully bio-based, porous, and wet stable 3D structures might have an opportunity in biomedical fields.

A concept for direct surface modification on self-standing films of cellulose nanofibrils (CNF) is demonstrated using an aminosilane group in cellulose compatible solvent (dimethyl acetamide, DMA). The chemically modified structure efficiently prevents the oxygen molecules from interacting with the nanocellulose film in the presence of water molecules. Oxygen permeability values lower than 1 mL mm m-2 day-1 atm-1 were achieved at extremely high levels of relative humidity (RH95%). The aminosilane reaction is compared to conventional hydrophobization reaction using hexamethyldisilazane. The differences with respect to interactions between cellulosic nanofibrils, water and oxygen molecules taking place with aminated and silylated CNF films correlated with the degree of surface substitution, surface hydrophilicity and permeability of the formed layer. The self-condensation reactions taking place on the film surface during aminosilane-mediated bonding were decisive for low oxygen permeability. Experimental evidence on the importance of interfacial processes that hinder the water-cellulose interactions while keeping film's low affinity towards oxygen is demonstrated.

International audience; This paper investigates the use of an aqueous dispersion of polyethylene copolymer with a relatively high content of acrylic acid as a compatibilizer and as an alternative medium to obtain polyethylene CNF nanocomposites. The CNF content was varied from 1 to 90 wt% and the appearance, optical, thermal, mechanical and rheological properties, as well the morphology of the films were evaluated. The PE/CNF films are transparent up to 20 wt% of NFC indicating a good dispersion of CNF, but a poor distribution, with PE-rich and CNF-rich regions observed by SEM. Improved mechanical properties were achieved, with a 100% and 15,900% increase in the Young’s modulus with 1 wt% and 90 wt% NFC, respectively. The rheological behavior indicated good melt processability. According to these results, aqueous polyolefin dispersions seem to be a promising, easy and relatively fast route for obtaining cellulose/polyolefins nanocomposites with low to high contents of cellulose nanofibrils.