Structure Of Nanocellulose Research Articles

Ultrasound effect on a biorefinery lignin-cellulose mixture

Forest biorefineries provide multiple new avenues for applied research. The main concept lies in the malleability of the processes and their stepwise organization. The core element of the biorefinery concept addressed in the present study is the pretreatment step; here, wood biomass is converted into free hemicellulosic sugars, lignin and cellulose. In traditional approaches, the pretreatment step is a starting point for isolating and separating lignin or cellulose through different processes. In this study, instead of performing any separation, a lignin-cellulose mixture was used as its own material, and the effects of ultrasound treatment with a probe system at 20 kHz, with various amplitude, sonication time and dry matter content were investigated with the aim of assessing the formation of a nanocellulose structure with a high lignin content (>30 %) and investigating the stability of the lignin-cellulose mixture under aqueous conditions. We demonstrated the importance of dry matter content for the specific particle size and water retention values for this mixture. US treatment of lignin-cellulose mixtures <4 % dry matter formed a gel-like material, with low particle size (90 % below 30 μm and smallest at nanoscale). Low dry matter loading led to better US transfer and higher conversion of cellulose to <100 nm nanoparticles. Our study can serve as a baseline for future developments in the field of stable emulsions, filtering materials or inputs for material synthesis.

Nanocellulose-Based Resistive Sensors for Air Humidity Measurements

Introduction. The measurement of relative air humidity plays a crucial role in various aspects of human life, such as climate control systems, medical breath and skin hydration monitoring. Typically, humidity sensors use inorganic materials and petroleum-derived polymers. However, there is a growing trend towards the transition to biodegradable materials, which eliminates the need for waste disposal.Problem Statement. Currently, nanocellulose (NC) has been being explored as a promising material for humidity sensors. However, the influence of the chemical composition and nanoparticle size of NC on the sensor characteristics remains understudied.Purpose. This study aims to investigate the influence of the chemical composition and structure of NC on the parameters of humidity sensors.Materials and Methods. NC has been synthesized from reed stalks and wheat straw bz the oxidation and acid hydrolysis methods. NC-film sensors having a mass within 0.3—3 mg have been fabricated. The static parameters (response, sensitivity, reversibility, and repeatability) and the dynamic parameters (short and long-term stability, response and recovery time) of the sensors have been analyzed.Results. The manufacturing method influences the NC chemical composition, while the origin material affects its structure. The sensors produced by the oxidation method have demonstrated improved sensitivity (2.69 · 106), response (0.2 (%RH)–1), recovery time (60 s) and long-term stability (1.44%) as compared with those made by the hydrolysis method. Additionally, the application of wheat straw NC as origin material has resulted in improved reversibility (5%), repeatability (5% deviation), short-term stability (30% deviation), and response time (1 s) as compared with the reed stalks NC.Conclusions. It has been established that the origin material of nanocellulose influences the reversibility, repeatability, response time, and short-term stability of the sensors. The manufacturing method has effect on the sensitivity, response, recovery time, and long-term stability of the sensors.

The Effect of H2SO4 Variations on the Synthesis and Characterization of Nanocellulose Using Pineapple Peel Fiber

Manufacturing nanocellulose made from pineapple peel fiber has been carried out using acid hydrolysis. This study aims to determine the effect of variations in H2SO4 on the synthesis of nanocellulose in pineapple peel fibers and on the crystal structure, surface morphology, and constituent elements of pineapple skin fiber nanocellulose. The variations of H2SO4 used were 5, 10, 15 and 20%. X-ray diffraction (XRD) and Scanning Electron microscopy (SEM) are characterizations used. The results of XRD characterization showed that the size of the resulting crystallite had met the appropriate size in the range of values from 2.03 – 2.21 nm. The results of SEM characterization show that the image is not porous and lumpy.

Nanocellulose as promising reinforcement materials for biopolymer nanocomposites: a review

Abstract. A green and sustainable development in world is important and it needs to further strengthen at the moment. In this aspect, biopolymers, biopolymers nanocomposites with biodegradable properties are the best way for this purpose. Nanocellulose (NC) is a biopolymer and can be produced from natural resources like various plant species and agricultural waste products including rice husk, tea leaves, sugarcane bagasse and so forth. Due to their special properties such as biodegradability, renewability, biocompability, low cost and outstanding mechanical capabilities, NC have gained increased research and application interests. This review provided detail information about the production, structure and properties of NC. The usage of NC as reinforcement materials for different types of biopolymers are presented in the review. The surface modification of NC for better dispersion and better interaction of NCs in polymer matrices, the mechanical and thermal properties of the NC biopolymers nanocomposites are discussed.

Efficient conversion of an underutilized low-lignin lignocellulosic biomass to cellulose nanocrystals and nanofibers via mild chemical-mechanical protocols

The production of high-quality nanocellulose (NC) from an underutilized low-lignin lignocellulosic biomass source, Phalaris aquatica L., was investigated via three conversion protocols. Initially, a conventional chemical protocol (Scenario I) was optimized using statistically designed experiments, and cellulose nanocrystals (CNCs) that exhibited an adequate crystallinity index (CI) were produced under mild conditions: short processing times, reduced temperatures and decreased use of chemicals and solvents. Hydrolysis temperature was found to contribute significantly to the variation of CI. Furthermore, two additional scenarios based on a planetary ball mill were comparatively applied, namely a combined chemical-mechanical (Scenario II) and an alternative (Scenario III) protocol, in which the ball milling step followed or replaced the acid hydrolysis step, respectively. In Scenarios II and III the NC structure was modified to cellulose nanofibrils (CNFs) and microfibrillated cellulose (MFC), respectively. Accordingly, the three different NC grades (CNCs, CNFs and MFC) were correlated with the three conversion protocols.

Preparation and characterization of sulfated nanocellulose: From hydrogels to highly transparent films

This study focuses on the production of sulfated cellulose microfibers and nanocellulose hydrogels from native cellulose microfibers (CMF). The process involves using a combination of H2SO4 and urea, resulting in highly sulfated cellulose microfiber hydrogel (SC) with notable properties such as a sulfur content of 7.5 %, a degree of sulfation of 0.49, a surface charge content of 2.2 mmol. g−1, and a high yield of 81 %. The SC hydrogel can be easily fibrillated into sulfated nanocellulose hydrogel (S-NC) with elongated nanocellulose structures having an average diameter of 6.85 ± 3.11 nm, as determined using atomic force microscopy (AFM). X-ray photoelectron spectroscopy (XPS) analysis confirms the presence of sulfate groups on the surface of the nanocellulose material. Transparent films with good mechanical properties can be produced from both cellulose microfiber and nanocellulose hydrogels. The sulfate functionality gives the hydrogel attractive rheological properties and makes S-NC re-dispersible in water, which can be beneficial for various applications. This study demonstrates the potential of this process to address previous challenges related to nanocellulose materials production.

Electron beam pre-irradiation enhances substitution degree, and physicochemical and functional properties of carboxymethyl peanut shell nanocellulose

Nanocellulose (NC) has attracted close attention in research and industry fields because of its excellent properties and plentiful hydroxyl group accessible for surface modification. In this study, the cellulose isolated from peanut shells was used to prepare carboxymethylated nanocellulose (CMNC) under different reaction conditions, and Electron beam irradiation (EBI) pretreatment with different doses (40, 80 and 120 KGy) was previously used before modification to improve the reaction accessibility of nanocellulose. The substitution degree (DS), structural, physicochemical and functional properties of carboxymethyl CMNC with EBI pretreatment were investigated. The results showed that the peanut shell nano cellulose was a typical rod-like structure with a diameter of 5–40 nm and a length of 50–300 nm, the aspect ratio distribution was about 6.37, and EBI pretreatment significantly improved the modification effect of CMNC. The DS of the unirradiated sample was 0.38 and 0.48, and the DS increased to 0.66 and 0.69 at the irradiation dose of 120 kGy, which increased by 74% and 44%, respectively. The carboxymethyl modification changed the morphology of nanocellulose from the original short rod-like to spherical particles, and the effect was more evident with the increase of irradiation dose. FTIR showed that the nanocellulose successfully introduced carboxyl groups, the crystalline structure of nanocellulose was changed by carboxymethyl reaction. The Zeta potential result showed that the dispersion stability of CMNC suspension was improved. These results provide a helpful basis for further investigations on the modification in nanocellulose induced by EBI, verifying the effectiveness and feasibility of using EBI to modify nanofibers. They are expected to guide the transformation of nanocellulose and its most possible applications in the future to improve its performance in different applications.

Translational applications of magnetic nanocellulose composites.

Nanocellulose has emerged as a potential 'green' material owing to its inimitable properties. Furthermore, the significant development in technology has facilitated the design of multidimensional nanocellulose structures, including one-dimensional (1D: microparticles and nanofibers), two-dimensional (2D: coatings), and three-dimensional (3D: hydrogels/ferrogels) composites. In this case, nanocellulose composites blended with magnetic nanoparticles represent a new class of hybrid materials with improved biocompatibility and biodegradability. The application field of magnetic nanocellulose composites (MNCs) ranges from biomedicine and the environment to catalysis and sensing. In this review, we present the major applications of MNCs, emphasizing their innovative benefits and how they interconnect with translational applications in clinics and the environment. Additionally, we focus on the synthesis techniques and role of different additives in the fabrication of MNCs for achieving extremely precise and intricate tasks related to real-world applications. Subsequently, we reveal the recent interdisciplinary research on MNCs and discuss their mechanical, tribological, electrochemical, magnetic, and biological phenomena. Finally, this review concludes with a portrayal of computational modelling together with a glimpse of the various translational applications of MNCs. Therefore, it is anticipated that the current review will provide the readers with an extensive opportunity and a more comprehensive depiction related to the types, properties, and applications of MNCs.

The Critical Roles of Water in the Processing, Structure, and Properties of Nanocellulose.

The cellulose industry depends heavily on water owing to the hydrophilic nature of cellulose fibrils and its potential for sustainable and innovative production methods. The emergence of nanocellulose, with its excellent properties, and the incorporation of nanomaterials have garnered significant attention. At the nanoscale level, nanocellulose offers a higher exposure of hydroxyl groups, making it more intimate with water than micro- and macroscale cellulose fibers. Gaining a deeper understanding of the interaction between nanocellulose and water holds the potential to reduce production costs and provide valuable insights into designing functional nanocellulose-based materials. In this review, water molecules interacting with nanocellulose are classified into free water (FW) and bound water (BW), based on their interaction forces with surface hydroxyls and their mobility in different states. In addition, the water-holding capacity of cellulosic materials and various water detection methods are also discussed. The review also examines water-utilization and water-removal methods in the fabrication, dispersion, and transport of nanocellulose, aiming to elucidate the challenges and tradeoffs in these processes while minimizing energy and time costs. Furthermore, the influence of water on nanocellulose properties, including mechanical properties, ion conductivity, and biodegradability, are discussed. Finally, we provide our perspective on the challenges and opportunities in developing nanocellulose and its interplay with water.

Cellulose Iβ behaviors in non-solvent liquid media: Molecular dynamic simulations

The structural changes of cellulose in non-solvent liquid media can provide insights into the high-value utilization of cellulose. This study includes molecular dynamics simulations of 36-chain cellulose Iβ microfibril model (Iβ-MF) behavior in 16 non-solvent liquids with different polarities at room temperature using two carbohydrate force fields (CHARMM36, GLYCAM06). Iβ-MF in CHARMM36 retains more than 70% of the tg conformation in 16 liquids, and the retention of the tg conformation increased with decreasing liquid polarity. Liquid polarity can affect the hydroxymethyl conformation of cellulose, which is only an appearance, and the real driving force behind is the electrostatic interaction between liquid molecules and cellulose. Furthermore, changing the 1,4 electrostatic scaling factor of GLYCAM06 can effectively affect the structural convergence of Iβ-MF. The Iβ-MF forms an alternating layer structure in the gg/gt conformation in a medium to high polarity non-solvent liquid, while the model undergoes untwisting. Model untwisting is inextricably linked to the degree of alternate layer structure formation. This paper provides a theoretical basis for the molecular study of nanocellulose structures from an energy-structure-property perspective.

Eco-benign synthesis of nano‑gold chitosan-bacterial cellulose in spent ground coffee kombucha consortium: Characterization, microbiome community, and biological performance

Biomaterials that are mediocre for cell adhesion have been a concern for medical purposes. In this study, we fabricated nano‑gold chitosan-bacterial cellulose (CBC-Au) via a facile in-situ method using spent ground coffee (SGC) in a kombucha consortium. The eco-benign synthesis of monodispersed gold nanoparticles (Au NPs) in modified bacterial cellulose (BC) was successfully achieved in the presence of chitosan (CHI) and a symbiotic culture of bacteria and yeast (SCOBY). The dominant microbiome community in SGC kombucha were Lactobacillaceae and Saccharomycetes. Chitosan–bacterial cellulose (CBC) and CBC-Au affected the microfibril networks in the nano cellulose structures and decreased the porosity. The modified BC maintained its crystallinity up to 80 % after incorporating CHI and Au NPs. Depth profiling using X-ray photoelectron spectroscopy (XPS) indicated that the Au NPs were distributed in the deeper layers of the scaffolds and a limited amount on the surface of the scaffold. Aspergillus niger fungal strains validated the biodegradability of each scaffold as a decomposer. Bacteriostatically CBC-Au showed better antimicrobial activity than BC, in line with the adhesion of NIH-3T3 fibroblast cells and red blood cells (RBCs), which displayed good biocompatibility performance, indicating its potential use as a medical scaffold.

Production of Nanocellulose from Kepok Banana Peel Waste Using Acid Hydrolysis Method

Research on the production of nanocellulose from kepok banana peel waste has been carried out using the Acid Hydrolysis method with H2SO4 Sulfuric Acid. This study aims to determine the effect of giving H2SO4 on kepok banana peels and the crystal structure and surface morphology of nanocellulose on kepok banana peels. The production of nanocellulose was carried out in three stages: delignification using 10% NaOH, bleaching using 10% H2O2, and isolation of nanocellulose using H2SO4 with various concentrations of 5, 10, 15, and 20%. This research uses X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) as its characterization. The resulting crystallite size ranges from 3.58 to 4.15 nm, producing a lump-like morphological structure.

Thermal, Mechanical and Morphological Properties of Cellulose/Lignin Nanocomposites

Lignin, a lignocellulosic polymer material, is an important active ingredient for the high-value use of renewable resources. Thus, policies for the recovery and high value-added use of renewable lignocellulosic biomass are a realistic engineering approach to address concerns such as the climate and energy crisis. In this work, the mechanical properties, thermal stability and morphology of cellulose/lignin nanocomposites were studied. Nanocomposite films containing different proportions of lignin (2.5%, 5%, 10% and 20%) were prepared. Thermal properties were assessed via thermogravimetric analysis and differential scanning calorimetry, mechanical properties via tensile test and morphological properties via scanning electron microscopy techniques. It was observed that nanolignin and nanocellulose structures are compatible with each other and depending on the main degradation temperature, the thermal stability of 2.5% lignin-containing nanocomposites is higher than that of other composites. From the results obtained, it was determined that the nanocomposite film containing 2.5% nanolignin had high thermal stability, mechanical strength and suitable morphological structure compared to other samples.

Nanocellulose Sponges Containing Antibacterial Basil Extract.

Nanocellulose (NC) is a valuable material in tissue engineering, wound dressing, and drug delivery, but its lack of antimicrobial activity is a major drawback for these applications. In this work, basil ethanolic extract (BE) and basil seed mucilage (BSM) were used to endow nanocellulose with antibacterial activity. NC/BE and NC/BE/BSM sponges were obtained from nanocellulose suspensions and different amounts of BE and BSM after freeze-drying. Regardless of the BE or BSM content, the sponges started to decompose at a lower temperature due to the presence of highly volatile active compounds in BE. A SEM investigation revealed an opened-cell structure and nanofibrillar morphology for all the sponges, while highly impregnated nanofibers were observed by SEM in NC/BE sponges with higher amounts of BE. A quantitative evaluation of the porous morphology by microcomputer tomography showed that the open porosity of the sponges varied between 70% and 82%, being lower in the sponges with higher BE/BSM content due to the impregnation of cellulose nanofibers with BE/BSM, which led to smaller pores. The addition of BE increased the specific compression strength of the NC/BE sponges, with a higher amount of BE having a stronger effect. A slight inhibition of S. aureus growth was observed in the NC/BE sponges with a higher amount of BE, and no effect was observed in the unmodified NC. In addition, the NC/BE sponge with the highest amount of BE and the best antibacterial effect in the series showed no cytotoxic effect and did not interfere with the normal development of the L929 cell line, similar to the unmodified NC. This work uses a simple, straightforward method to obtain highly porous nanocellulose structures containing antibacterial basil extract for use in biomedical applications.

3D printing of concentrated nanocellulose material: The critical role of substrates on the shape fidelity and mechanical properties

This paper presents a breakthrough in the shape fidelity and mechanical strength of 3D-printed high-concentration nanocellulose structures, demonstrating a record flexural strength of 149 ± 2 MPa and a flexural modulus of 15 ± 0.8 GPa. These findings replace the previous method of 3D printing on conventional substrates with wood substrates for highly concentrated nanocellulose (HCNC) structures. The HCNC structures are 3D-printed using extrusion and processed under controlled drying conditions (Relative humidity: 60 % and 45 %, Temperature: 25 °C) to achieve outstanding mechanical properties without sacrificing structure shape fidelity/retention. It was noticed that the drying phenomenon of HCNC structures on the conventional substrates is responsible for the adhesion issues between the printed layers resulting in low shape fidelity/retention. In contrast with conventional substrates, the wood substrates offer an increased drying rate from the bottom side of printed HCNC structures due to its hydrophilicity and wicked nature, which helps maintain the shape fidelity without using additional crosslinkers, resulting in improved shape fidelity/retention and mechanical properties. The 3D-printed nanocellulose structure bears twice the load compared to a commercial poly lactic acid 3D-printed one. These features open a new horizon for fabricating 3D-printed nanocellulose structures for advanced environmentally friendly structural applications.

Role of Nanocellulose in Light Harvesting and Artificial Photosynthesis

Artificial photosynthesis has rapidly developed as an actual field of research, mimicking natural photosynthesis processes in plants or bacteria to produce energy or high-value chemicals. The nanocelluloses are a family of biorenewable materials that can be engineered into nanostructures with favorable properties to serve as a host matrix for encapsulation of photoreactive moieties or cells. In this review, the production of different nanocellulose structures such as films, hydrogels, membranes, and foams together with their specific properties to function as photosynthetic devices are described. In particular, the nanocellulose’s water affinity, high surface area and porosity, mechanical stability in aqueous environment, and barrier properties can be tuned by appropriate processing. From a more fundamental viewpoint, the optical properties (transparency and haze) and interaction of light with nanofibrous structures can be further optimized to enhance light harvesting, e.g., by functionalization or appropriate surface texturing. After reviewing the basic principles of natural photosynthesis and photon interactions, it is described how they can be transferred into nanocellulose structures serving as a platform for immobilization of photoreactive moieties. Using photoreactive centers, the isolated reactive protein complexes can be applied in artificial bio-hybrid nanocellulose systems through self-assembly, or metal nanoparticles, metal-organic frameworks, and quantum dots can be integrated in nanocellulose composites. Alternatively, the immobilization of algae or cyanobacteria in nanopaper coatings or a porous nanocellulose matrix allows to design photosynthetic cell factories and advanced artificial leaves. The remaining challenges in upscaling and improving photosynthesis efficiency are finally addressed in order to establish a breakthrough in utilization of nanocellulose for artificial photosynthesis.

Molecular Dynamics of Drying-Induced Structural Transformations in a Single Nanocellulose.

Nanocellulose is attracting attention in the field of materials science as a sustainable building block. Nanocellulose-based materials, such as films, membranes, and foams, are fabricated by drying colloidal dispersions. However, little is known about how the structure of a single nanocellulose changes during the complex drying process. Here, all-atom molecular dynamics simulations and atomic force microscopy is used to investigate the structural dynamics of single nanocellulose during drying. It is found that the twist morphology of the nanocellulose became localized along the fibril axis during the final stage of the drying process. Moreover, it is shown that conformational changes at C6 hydroxymethyl groups and glycoside bond is accompanied by the twist localization, indicating that the increase in the crystallinity occurred in the process. It is expected that the results will provide molecular insights into nanocellulose structures in material processing, which is helpful for the design of materials with advanced functionalities.

Tailoring an Effective Interface between Nanocellulose and the Epoxidized Linseed Oil Network through Functionalization.

Sustainable nanocomposite materials based on different functionalized nanocellulose (NC) structures embedded in epoxidized linseed oil (ELO) were developed as foundation toward a greener approach for anticorrosive coating evolution. The work leans on functionalization with (3-aminopropyl) triethoxysilane (APTS), (3-glycidyloxypropyl)trimethoxysilane (GPTS), and vanillin (V) of NC structures isolated from plum seed shells, evaluated as potential reinforcing agents for the increase of thermomechanical properties and water resistance of epoxy nanocomposites from renewable resources. The successful surface modification was confirmed from the deconvolution of X-ray photoelectron spectra for C 1s and correlated with Fourier transform infrared (FTIR) data. The secondary peaks assigned to C-O-Si at 285.9 eV and C-N at 286 eV were observed with the decrease of the C/O atomic ratio. Compatibility and efficient interface formation between the functionalized NC and the biobased epoxy network from linseed oil were translated as decreased values for the surface energy of bio-nanocomposites and better dispersion imaged through scanning electron microscopy (SEM). Thus, the storage modulus of the ELO network reinforced with only 1% APTS-functionalized NC structures reached 5 GPa, an almost 20% increase compared with that of the neat matrix. Mechanical tests were applied to assess an increase of 116% in compressive strength for the addition of 5 wt % NCA to the bioepoxy matrix.

Composite magnetic properties of cobalt ferrite nanoparticles embedded in bacterial nanocellulose of different porosity levels

A simple and novel strategy for tuning the macroporous structure of bacterial nanocellulose allows for embedding nanoparticles on the template. Here, cobalt ferrite nanoparticles were co-precipitated in-situ at two templates with different porosities. Different analytical techniques like SEM, XRD, TGA, and PPMS allow for characterizing the properties of the prepared magnetic nanocomposites. After eight months of aging at room conditions, lyophilized bacterial nanocellulose preserved the macroporous structure (porosity ∼ 46%). However, rehydration and re-lyophilization of the cellulose decrease the template porosity (∼8%). The cobalt ferrite nanoparticles, growth on high and low macroporous templates, were single-crystalline and microstrain-free. The nanoparticle's shape and mean size do not change with the porosity of the template, but the cluster size does. However, the differences in porosity on templates allow tuning the nanoparticle concentration and then its magnetic interactions (in high macroporous near 63%, and low about 43%) in the nanocomposites. Magnetic data confirm the influence of the template porosity on the magnetic particle concentration. The magnetic behavior as a temperature function (effective magnetic anisotropy constant, coercive force, and reduced remanence) is dependent on the template porosity. These dissimilarities were correlated with cluster size variations, where the differences in the aggregation modify the magnetic dipolar interactions among particles.

Additively-Manufactured High-Concentration Nanocellulose Composites: Structure and Mechanical Properties.

Additive manufacturing technology (AMT) has transformed polymer composites' manufacturing process with its exceptional ability to construct complex products with unique materials, functions, and structures. Besides limiting studies of manufacturing arbitrarily shaped composites using AMT, printed structures with a high concentration of nanocellulose face adhesion issues upon drying, resulting in shape fidelity issues and low mechanical strength. This research demonstrates an economical approach to printing a high-concentration (25.46 wt%) nanocellulose (NC) layer-wise pattern to fabricate structures. Two different composites are fabricated: (1) 3D-printed pure and high-concentration (10, 15, and 20 wt%) polyvinyl-alcohol (PVA)-blended NC structures followed by freeze-drying and impregnation of Epofix resin by varying hardener contents; (2) 3D-printed PVA-blended NC green composites dried at cleanroom conditions (Relative humidity 45%; Temperature 25 °C). Different contents (10, 15, and 20 wt%) of PVA as a crosslinker were blended with NC to assist the printed layers' adhesions. An optimum PVA content of 15 wt% and an Epofix resin with 4 wt% hardener cases showed the highest bending strength of 55.41 ± 3.63 MPa and elastic modulus of 4.25 ± 0.37 GPa. In contrast, the 15 wt% PVA-blended NC cleanroom-dried green composites without resin infusion showed bending strength and elastic modulus of 94.78 ± 3.18 MPa and 9.00 ± 0.27 GPa, reflecting high interface adhesions as confirmed by scanning electron microscope. This study demonstrated that AMT-based nanocellulose composites could be scaled up for commercial use.