Cellulose Nanofibers from Softwood, Hardwood, and Tunicate: Preparation-Structure-Film Performance Interrelation

Hydrophobic corn zein-modified cellulose nanofibril (CNF) films with antioxidant properties

Cellulose nanofibrils (CNFs) can form strong biodegradable films; however, due to their hydrophilicity, moisture can degrade their mechanical and barrier properties. Corn zein (CZ) is a hydrophobic protein that when covalently linked with CNF films through peptide bonds, may improve their hydrophobicity. CZ was covalently linked to aminophenylacetic acid and aminobenzoic acid esterified CNF films which were then assessed for evidence of modification, hydrophobicity, mechanical properties, and antioxidant activity. Upon modification, an increase in hydrophobicity and an increase in antioxidant activity as evidenced by 57% higher 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and 26% higher (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) ABTS scavenging activities when compared to control CNF films, and reduced thio barbituric acid reactive substances (TBARS) values in canola oil during 14 days of 50 °C storage were noted. Results demonstrate that modification of CNF films with a hydrophobic protein such as CZ can increase the hydrophobicity of these biodegradable films while providing active antioxidant functionality.

Processing factors affecting roughness, optical and mechanical properties of nanocellulose films for optoelectronics

This work aims to understand how nanocellulose (NC) processing can modify the key characteristics of NC films to align with the main requirements for high-performance optoelectronics. The performance of these devices relies heavily on the light transmittance of the substrate, which serves as a mechanical support and optimizes light interactions with the photoactive component. Critical variables that determine the optical and mechanical properties of the films include the morphology of cellulose nanofibrils (CNF), as well as the concentration and turbidity of the respective aqueous suspensions. This study demonstrates that achieving high transparency was possible by reducing the grammage and adjusting the drying temperature through hot pressing. Furthermore, the use of modified CNF, specifically carboxylated CNF, resulted in more transparent films due to a higher nanosized fraction and lower turbidity. The mechanical properties of the films depended on their structure, homogeneity (spatial uniformity of local grammage), and electrokinetic factors, such as the presence of electrostatic charges on CNF. Additionally, we investigated the angle-dependent transmittance of the CNF films, since solar devices usually operate under indirect light. This work demonstrates the importance of a systematic approach to the optimization of cellulose films, providing valuable insight into the optoelectronic field.

Cationic cellulose nanofibers/chitosan auxiliary-dominated win-win strategy for paper yarn with superior color and physical performances

The colored and high-saline effluents during the traditional dyeing process poses serious environmental challenge. In our study, an eco-friendly cationic cellulose nano-fiber/chitosan (CCNF/CS) binary versatile auxiliary was designed for the neutral salt-free dyeing and physical enhancement of paper by mixing with pulp simply. Profiting from the rich cationic binding sites of CCNF/CS (Charge density: 3749.67 μmol/g), under near neutral conditions (pH = 6.2), the maximum adsorption capacity of anionic GL (Direct fast turquoise blue GL) on paper with 0.5 % CCNF/CS reached 1865.06 mg/g with a desirable evenness (45.5 % and 92.1 % higher than that of CCNF and NaCl group, respectively), and the dye uptake was up to 97 %. The spontaneous adsorption behavior was aligned with the pseudo-second-order and Langmuir models, with a primary physical mechanism enhanced by chemical forces. The combination of strong electronic attraction, hydrogen bonding, and n-π stacking effects granted CCNF/CS an enhanced proficiency in anionic dye adsorption. In addition, the tensile strength of the resulting paper yarn with 0.5 % CCNF/CS increased to 52.47 MPa under the optimal parameters, deriving from the CCNF/CS-induced inter-fiber cohesion. Overall, our research provided a green promising approach for the innovative neutral salt-free dyeing and mechanical enhancement of paper.

Preparation and characterization of a novel high barrier mulching film with tunicate cellulose nanocrystals/sodium alginate/alkali lignin

In this study, the base film (CSL) was prepared by blending tunicate cellulose nanocrystals (TCNCs) extracted from tunicate shells, with sodium alginate (SA) and alkali lignin (AL). Then, the mulching film (CSL-WK) was prepared using water-borne polyurethane (WPU) as binder to install low-energy Kaolin on the surface of CSL film. The influences of composition with different concentrations on mechanical properties were studied. The tensile strength and elongation at break of CSL-WK film could reach 86.58 MPa and 50.49 %, respectively. The mulching films were characterized by degradability test, SEM, FTIR, and TGA. TCNCs had good compatibility with SA and AL, and a rough structure was formed on the surface of the film to improve the hydrophobicity. The barrier properties, including ultraviolet resistance, water contact angle, water vapor permeability, water retention, and flame retardancy, were tested. The results showed that CSL-WK films could block 97 % of ultraviolet light, reduce about 25 % of soil water loss, and self-extinguish within 7 s of open flame ignition. Note that the secondary spraying method significantly improved the barrier property of films. This study lays a foundation for the preparation of ecologically friendly, biodegradable, and high barrier mulching film, and expands the application of marine resources.

Adjustable strength and toughness of dual cross-linked nanocellulose films via spherical cellulose as soft-phase

Nanocellulose films possess numerous merits ascribing to their inherent biocompatibility, non-toxic and biodegradability properties. The potential for practical applications would be improved if their mechanical strength and toughness requirements could be met simultaneously. Herein, dual cross-linked nanocellulose (DC) film was fabricated by the treatments of chemical and physical cross-linking, which was mechanically superior to pure nanocellulose (CNF) films. To further increase the toughness of DC films, spherical cellulose (Sph) was incorporated into DC film (DC-Sph film), and analyzed under different humidity conditions (RH) (from 10 % to 90 %). The changes of functional groups of CNF, DC and DC-Sph films were detected by FTIR and XPS spectrum. The epichlorohydrin and Sph content were optimized, followed by the investigation of RH on the toughness of films. The highest tensile strength (146.6 ± 4.6 MPa) was obtained in DC film at 50 % RH, while the DC-Sph film showed the largest toughness (40.3 ± 3.7 kJ/m2) at 70 % RH. Furthermore, the possible toughening mechanism of DC-Sph film was also discussed.

Multifunctional Poly(3,4-ethylenedioxythiophene)/Crystalline Nanofibrous Cellulose Composites for Eco-Friendly and Sustainable Electronics

Nanocellulose constitutes promising resources for next-generation electronics, particularly when incorporated with conductive polymers due to their abundance, renewability, processability, biodegradability, flexibility, and mechanical performance. In this study, electrically conducting cellulose nanofibers were fabricated through in situ chemical polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT) on the surface of sulfuric acid-treated cellulose nanofibers (SACN). The utilization of highly crystalline SACN extracted from tunicate yielded synergistic effects in PEDOT polymerization for achieving a highly conductive and molecularly uniform coating. Polymerization parameters, such as monomer concentration, molar ratio with oxidants, and temperature, were systematically investigated. High electrical conductivity of up to 57.8 S cm-1 was obtained without utilizing the classical polystyrenesulfonate dopant. The resulting nanocomposite demonstrates the unique advantages of both electrically conductive PEDOT and mechanically robust high-crystalline cellulose nanofibers. As a proof-of-applicational concept, an electrical circuit was drawn with SACN-PEDOT as the conductive ink on flexible paper using a simple commercial extrusion-based printer. Furthermore, the flame-retardant property of SACN-PEDOT was demonstrated owing to the high crystallinity of SACN, effective char formation, and high conductivity of PEDOT. The multifunctional SACN-PEDOT developed in this study shows great promise to be employed in versatile applications as a low-cost, ecofriendly, flexible, and sustainable electrically conductive material.

Cellulose nanocrystals in the development of biodegradable materials: A review on CNC resources, modification, and their hybridization

The escalating demand for sustainable materials has propelled cellulose into the spotlight as a promising alternative to petroleum-based products. As the most abundant organic polymer on Earth, cellulose is ubiquitous, found in plants, bacteria, and even a unique marine animal-the tunicate. Cellulose polymers naturally give rise to microscale semi-crystalline fibers and nanoscale crystalline regions known as cellulose nanocrystals (CNCs). Exhibiting rod-like structures with widths spanning 3 to 50 nm and lengths ranging from 50 nm to several microns, CNC characteristics vary based on the cellulose source. The degree of crystallinity, crucial for CNC properties, fluctuates between 49 and 95 % depending on the source and synthesis method. CNCs, with their exceptional properties such as high aspect ratio, relatively low density (≈1.6 g cm-3), high axial elastic modulus (≈150 GPa), significant tensile strength, and birefringence, emerge as ideal candidates for biodegradable fillers in nanocomposites and functional materials. The percolation threshold, a mathematical concept defining long-range connectivity between filler and polymer, governs the effectiveness of reinforcement in nanocomposites. This threshold is intricately influenced by the aspect ratio and molecular interaction strength, impacting CNC performance in polymeric and pure nanocomposite materials. This comprehensive review explores diverse aspects of CNCs, encompassing their derivation from various sources, methods of modification (both physical and chemical), and hybridization with heterogeneous fillers. Special attention is devoted to the hybridization of CNCs derived from tunicates (TCNC) with those from wood (WCNC), leveraging the distinct advantages of each. The overarching objective is to demonstrate how this hybridization strategy mitigates the limitations of WCNC in composite materials, offering improved interaction and enhanced percolation. This, in turn, is anticipated to elevate the reinforcing effects and pave the way for the development of nanocomposites with tunable viscoelastic, physicochemical, and mechanical properties.

Biotechnological innovations in nanocellulose production from waste biomass with a focus on pineapple waste

New materials' synthesis and utilization have shown many critical challenges in healthcare and other industrial sectors as most of these materials are directly or indirectly developed from fossil fuel resources. Environmental regulations and sustainability concepts have promoted the use of natural compounds with unique structures and properties that can be biodegradable, biocompatible, and eco-friendly. In this context, nanocellulose (NC) utility in different sectors and industries is reported due to their unique properties including biocompatibility and antimicrobial characteristics. The bacterial nanocellulose (BNC)-based materials have been synthesized by bacterial cells and extracted from plant waste materials including pineapple plant waste biomass. These materials have been utilized in the form of nanofibers and nanocrystals. These materials are found to have excellent surface properties, low density, and good transparency, and are rich in hydroxyl groups for their modifications to other useful products. These materials are well utilized in different sectors including biomedical or health care centres, nanocomposite materials, supercapacitors, and polymer matrix production. This review explores different approaches for NC production from pineapple waste residues using biotechnological interventions, approaches for their modification, and wider applications in different sectors. Recent technological developments in NC production by enzymatic treatment are critically discussed. The utilization of pineapple waste-derived NC from a bioeconomic perspective is summarized in the paper. The chemical composition and properties of nanocellulose extracted from pineapple waste may have unique characteristics compared to other sources. Pineapple waste for nanocellulose production aligns with the principles of sustainability, waste reduction, and innovation, making it a promising and novel approach in the field of nanocellulose materials.

One-step wet-spinning of conducting polymer and cellulose nanofiber composites for fiber-type organic electrochemical transistors

Considering that textile-based sensors are suitable for monitoring/communicating human vital health information, organic electrochemical transistors (OECTs) are considered as an efficient device platform for augmenting the capabilities and effectiveness of smart textile applications in diverse areas. Herein, we investigated the fabrication process and properties of poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)-TEMPO-oxidized cellulose nanofiber (CNF) composites as active channel materials for fiber-type OECTs. Utilizing highly crystalline, mechanically rigid, and chemically robust CNFs directly extracted from biomass-derived tunicate, we fabricated PEDOT:PSS-CNF composite fibers with varying CNF portions (0, 5, 10, 20, and 30 %) through a simple one-step wet-spinning process using sulfuric acid-based coagulation media. The addition of CNFs significantly improved the mechanical strength of the composite fibers with Young's modulus up to 13.4 ± 2.1 GPa. Moreover, the fiber-type OECT devices based on the PEDOT:PSS(80 %)-CNF(20 %) composite showed highest carrier mobility (4.0 ± 0.2 cm2 V-1 s-1) with the marginal trade-off in volumetric capacitance (57.1 ± 3.7 F/cm3), resulting in the decent benchmark performance parameter (μ·C*) of 229 F cm-1 V-1 s-1. Our findings suggest that the synergistic interaction between PEDOT:PSS and CNFs leads to a significant improvement in fiber properties, and the resulting composite fibers hold great potentials for use in eco-friendly wearable/textile electronics.

Preparation and Characterization of Softwood and Hardwood Nanofibril Hydrogels: Toward Wound Dressing Applications

Hydrogels of cellulose nanofibrils (CNFs) are promising wound dressing candidates due to their biocompatibility, high water absorption, and transparency. Herein, two different commercially available wood species, softwood and hardwood, were subjected to TEMPO-mediated oxidation to proceed with delignification and oxidation in a one-pot process, and thereafter, nanofibrils were isolated using a high-pressure microfluidizer. Furthermore, transparent nanofibril hydrogel networks were prepared by vacuum filtration. Nanofibril properties and network performance correlated with oxidation were investigated and compared with commercially available TEMPO-oxidized pulp nanofibrils and their networks. Softwood nanofibril hydrogel networks exhibited the best mechanical properties, and in vitro toxicological risk assessment showed no detrimental effect for any of the studied hydrogels on human fibroblast or keratinocyte cells. This study demonstrates a straightforward processing route for direct oxidation of different wood species to obtain nanofibril hydrogels for potential use as wound dressings, with softwood having the most potential.

Cellulosic Textiles-An Appealing Trend for Different Pharmaceutical Applications

Cellulose, the most abundant biopolymer in nature, is derived from various sources. The production of pharmaceutical textiles based on cellulose represents a growing sector. In medicated textiles, textile and pharmaceutical sciences are integrated to develop new healthcare approaches aiming to improve patient compliance. Through the possibility of cellulose functionalization, pharmaceutical textiles can broaden the applications of cellulose in the biomedical field. This narrative review aims to illustrate both the methods of extraction and preparation of cellulose fibers, with a particular focus on nanocellulose, and diverse pharmaceutical applications like tissue restoration and antimicrobial, antiviral, and wound healing applications. Additionally, the merging between fabricated cellulosic textiles with drugs, metal nanoparticles, and plant-derived and synthetic materials are also illustrated. Moreover, new emerging technologies and the use of smart medicated textiles (3D and 4D cellulosic textiles) are not far from those within the review scope. In each section, the review outlines some of the limitations in the use of cellulose textiles, indicating scientific research that provides significant contributions to overcome them. This review also points out the faced challenges and possible solutions in a trial to present an overview on all issues related to the use of cellulose for the production of pharmaceutical textiles.

Hemp cellulose nanocrystals for functional chitosan/polyvinyl alcohol-based films for food packaging applications

Hemp is known for its swift growth and remarkable sustainability, requiring significantly less water, an adaptable cultivation to a wide range of climates when compared to other fibers sources, making it a practical and environmentally friendly choice for packaging materials. The current research seeks to extract cellulose nanocrystals (CNCs) from hemp fibers using alkali treatment followed by acid hydrolysis and assess their reinforcing capacity in polyvinyl alcohol (PVA) and chitosan (CS) films. AFM analysis confirmed the existence of elongated, uniquely nanosized CNC fibers. The length of the isolated CNCs was approximately 277.76 ± 61 nm, diameter was 6.38 ± 1.27 nm and its aspect ratio was 44.69 ± 11.08. The FTIR and SEM analysis indicated the successful removal of non-cellulosic compounds. Furthermore, the study explored the impact of adding CNCs at varying weight percentages (0, 0.5, 1, 2.5, and 5 wt%) as a strengthening agent on the chemical composition, structure, tensile characteristics, transparency, and water solubility of the bionanocomposite films. Adding CNCs to the CS/PVA film, up to 5 wt%, resulted in an improvement in both the Young's modulus and tensile strength of the bionanocomposite film, which are measured at (412.46 ± 10.49 MPa) and (18.60 ± 3.42 MPa), respectively, in contrast to the control films with values of (202.32 ± 22.50 MPa) and (13.72 ± 2.61 MPa), respectively. The scanning electron microscopy (SEM) images reveal the creation of a CS/PVA/CNC film that appears smooth, with no signs of clumping or clustering. The blending and introduction of CNCs have yielded transparent and biodegradable CS/PVA films. This incorporation has led to a reduction in the gas transmission rate (from 7.013 to 4.159 cm3 (m2 day·0.1 MPa))-1, a decrease in transparency (from 90.23% to 82.47%), and a lowered water solubility (from 48% to 33%). This study is the inaugural effort to propose the utilization of hemp-derived CNC as a strengthening component in the development of mechanically robust and transparent CS/PVA-CNC bio-nanocomposite films, holding substantial potential for application in the field of food packaging.

Conceptual Design of a Sustainable Bionanocomposite Bracket for a Transmission Tower’s Cross Arm Using a Hybrid Concurrent Engineering Approach

This research article elaborates on the conceptual design development of a sustainable bionanocomposite bracket for bracing installation in composite cross arm structures. The product design development employed the hybrid techniques of the theory of inventive problem solving (TRIZ), morphological chart, and analytic network process (ANP) methods. The current bracket design in the braced composite cross arm is composed of heavy and easy-to-rust steel material. Therefore, this research aims to develop a new bionanocomposite bracket design to replace the heavy and easy-to-rust steel bracket. This research also aims to implement a concurrent engineering approach for the conceptual design of bionanocomposite bracket installation to enhance the overall insulation performance. A preliminary process was implemented, which covered the relationship between the current problem of the design and design planning to build a proper direction to create a new design product using TRIZ. Later, the TRIZ inventive solution was selected based on the engineering contradiction matrix with specific design strategies. From the design strategies, the results were refined in a morphological chart to form several conceptual designs to select the ANP technique to systematically develop the final conceptual design of the bionanocomposite bracket for the cross arm component. The outcomes showed that Concept Design 1 scored the highest and ranked first among the four proposed designs. The challenges of the bionanocomposite bracket design for cross arm structures and the improvement criteria in concurrent engineering are also presented.

Fractionation of Aspen Wood to Produce Microcrystalline, Microfibrillated and Nanofibrillated Celluloses, Xylan and Ethanollignin

A new method for extractive-catalytic fractionation of aspen wood to produce microcrystalline (MCC), microfibrillated (MFC), nanofibrilllated (NFC) celluloses, xylan, and ethanollignin is suggested in order to utilize all of the main components of wood biomass. Xylan is obtained with a yield of 10.2 wt.% via aqueous alkali extraction at room temperature. Ethanollignin was obtained with a yield of 11.2 wt.% via extraction with 60% ethanol from the xylan-free wood at 190 °C. The lignocellulose residue formed after the extraction of xylan and ethanollignin was subjected to catalytic peroxide delignification in the acetic acid-water medium at 100 °C in order to obtain microcrystalline cellulose. MCC is hydrolyzed with 56% sulfuric acid and treated with ultrasound to produce microfibrillated cellulose and nanofibrillated cellulose. The yields of MFC and NFC were 14.4 and 19.0 wt.%, respectively. The average hydrodynamic diameter of NFC particles was 36.6 nm, the crystallinity index was 0.86, and the average zeta-potential was 41.5 mV. The composition and structure of xylan, ethanollignin, cellulose product, MCC, MFC, and NFC obtained from aspen wood were characterized using elemental and chemical analysis, Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analyses, Gas chromatography (GC), Gel permeation-chromatography (GPC), Scanning electron microscopy (SEM), Atomic force microscopy (AFM), Dynamic light scattering (DLS), Thermal gravimetric analysis (TGA).

All-Tunicate Cellulose Film with Good Light Management Properties for High-Efficiency Organic Solar Cells

Tunicate nanocellulose with its unique properties, such as excellent mechanical strength, high crystallinity, and good biodegradability, has potential to be used for the preparation of light management film with tunable transmittance and haze. Herein, we prepared a whole tunicate cellulose film with tunable haze levels, by mixing tunicate microfibrillated cellulose (MFC) and tunicate cellulose nanofibrils (CNF). Then, the obtained whole tunicate cellulose film with updated light management was used to modify the organic solar cell (OSC) substrate, aiming to improve the light utilization efficiency of OSC. Results showed that the dosage of MFC based on the weight of CNF was an important factor to adjust the haze and light transmittance of the prepared cellulose film. When the dosage of MFC was 3 wt.%, the haze of the obtained film increased 74.2% compared to the pure CNF film (39.2%). Moreover, the optimized tunicate cellulose film exhibited excellent mechanical properties (e.g., tensile strength of 168 MPa, toughness of 5.7 MJ/m³) and high thermal stability, which will be beneficial to the workability and durability of OSC. More interestingly, we applied the obtained whole tunicate cellulose film with a high haze (68.3%) and high light transmittance (85.0%) as an additional layer to be adhered to the glass substrate of OSC, and a notable improvement (6.5%) of the power conversion efficiency was achieved. With the use of biodegradable tunicate cellulose, this work provides a simple strategy to enhance light management of the transparent substrate of OSC for improving power conversion efficiency.

Elucidating the fine-scale structural morphology of nanocellulose by nano infrared spectroscopy

Nanoscale infrared (IR) spectroscopy and microscopy, enabling the acquisition of IR spectra and images with a lateral resolution of 20 nm, is employed to chemically characterize individual cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) to elucidate if the CNCs and CNFs consist of alternating crystalline and amorphous domains along the CNF/CNC. The high lateral resolution enables studies of the nanoscale morphology at different domains of the CNFs/CNCs: flat segments, kinks, twisted areas, and end points. The types of nanocellulose investigated are CNFs from tunicate, CNCs from cotton, and anionic and cationic wood-derived CNFs. All nano-FTIR spectra acquired from the different samples and different domains of the individual nanocellulose particles resemble a spectrum of crystalline cellulose, suggesting that the non-crystalline cellulose signal observed in macroscopic measurements of nanocellulose most likely originate from cellulose chains present at the surface of the nanocellulose particles.

All-cellulose air filter composed with regenerated nanocellulose prepared through a facile method with shear-induced

High-speed shear system is usually used for the dispersion improvement of slurry, nanomaterials preparation, and even two-dimensional materials production. However, there is barely study that focused on the regenerated cellulose (RC) which was coagulated with shear induced. In this work, a new type of all-cellulose air filter was fabricated through high-speed shear in aqueous regeneration system using parenchyma cellulose from corn stalk. The obtained RC were aggregated by ribbon-like fine cellulose and nanocellulose sheets. The study exhibited the micro-structure of RC displayed excellent unidirectional alignment and a relatively high crystallinity. All-cellulose air filter which was produced via RC presented excellent filtration efficiency (PM_2.5 97.3 %, PM_10.0 97.7 %) with slightly pressure drop (19 Pa). Therefore, this work provides a facile method to obtain a novel RC with nanocellulose particles used for air filtration, which gives an effective strategy application in the conversion of all-cellulose materials from agricultural waste.

Microfibrillated Cellulose with a Lower Degree of Polymerization; Synthesis via Sulfuric Acid Hydrolysis under Ultrasonic Treatment

A new approach is being considered for obtaining microfibrillated cellulose with a low degree of polymerization by sulfuric acid hydrolysis with simultaneous ultrasonic treatment under mild conditions (temperature 25 °C, 80% power control). Samples of initial cellulose, MCC, and MFC were characterized by FTIR, XRF, SEM, DLS, and TGA. It was found that a high yield of MFC (86.4 wt.%) and a low SP (94) are observed during hydrolysis with ultrasonic treatment for 90 min. It was shown that the resulting microfibrillated cellulose retains the structure of cellulose I and has an IC of 0.74. It was found that MFC particles are a network of fibrils with an average size of 91.2 nm. ζ-potential of an aqueous suspension of MFC equal to -23.3 mV indicates its high stability. It is noted that MFC has high thermal stability, the maximum decomposition temperature is 333.9 °C. Simultaneous hydrolysis process with ultrasonic treatment to isolate MFC from cellulose obtained by oxidative delignification of spruce wood allows to reduce the number of stages, reduce energy costs, and expand the scope.

Effect of cellulose nanofibers on the fracture toughness mode II of glass fiber/epoxy composite laminates

Cellulose nanofibers (CNFs) were used to improve the fracture toughness of glass fiber reinforced epoxy composites (GFRPs). Different CNF suspensions were prepared and sprayed onto the surface of woven glass fiber laminates. The vacuum resin transfer molding (VaRTM) process was used to manufacture the GFRP composites. End notch flexure tests were conducted to evaluate the effect of CNFs on the critical energy release rate in mode II fracture toughness G_IIC. The results revealed that 0.05 wt% was the optimum concentration. The interlaminar fracture toughness G_IIC was improved by 28% with the addition of 0.05 wt% of CNFs to GF/epoxy composites. Whereas 0.1 wt% of CNFs resulted in decreasing G_IIC due to the uncomplete impregnation of GF with epoxy resin caused by the thicker CNF layer at the interfacial laminates. The toughening mechanisms were investigated using a field-emission electron microscope. Large epoxy deformations and shear hackles were predominant for improving the interlaminar fracture toughness of GFRP composites.

Material and Environmental Properties of Natural Polymers and Their Composites for Packaging Applications—A Review

The current trend of using plastic material in the manufacturing of packaging products raises serious environmental concerns due to waste disposal on land and in oceans and other environmental pollution. Natural polymers such as cellulose, starch, chitosan, and protein extracted from renewable resources are extensively explored as alternatives to plastics due to their biodegradability, biocompatibility, nontoxic properties, and abundant availability. The tensile and water vapor barrier properties and the environmental impacts of natural polymers played key roles in determining the eligibility of these materials for packaging applications. The brittle behavior and hydrophilic nature of natural polymers reduced the tensile and water vapor barrier properties. However, the addition of plasticizer, crosslinker, and reinforcement agents substantially improved the mechanical and water vapor resistance properties. The dispersion abilities and strong interfacial adhesion of nanocellulose with natural polymers improved the tensile strength and water vapor barrier properties of natural polymer-based packaging films. The maximum tensile stress of these composite films was about 38 to 200% more than that of films without reinforcement. The water vapor barrier properties of composite films also reduced up to 60% with nanocellulose reinforcement. The strong hydrogen bonding between natural polymer and nanocellulose reduced the polymer chain movement and decreased the percent elongation at break up to 100%. This review aims to present an overview of the mechanical and water vapor barrier properties of natural polymers and their composites along with the life cycle environmental impacts to elucidate their potential for packaging applications.

Cellulose: Characteristics and applications for rechargeable batteries

Cellulose, an abundant natural polymer, has promising potential to be used for energy storage systems because of its excellent mechanical, structural, and physical characteristics. This review discusses the structural features of cellulose and describes its potential application as an electrode, separator, and binder, in various types of high-performing batteries. Various surface and structural characteristics of cellulose (e.g., fiber size, surface functional groups, the hierarchy of pores, and porosity levels) that contribute to its electrochemical performance are discussed. Cellulose structure/property/processing/function relationships are further focused and elucidated in terms of the latest developments in the emerging field of sustainable materials in Li-Ion, Na-Ion, and LiS batteries.

Biomedical engineering aspects of nanocellulose: a review

Cellulose is one of the most abundant renewable biopolymer in nature and is present as major constituent in both plant cell walls as well as synthesized by some microorganisms as extracellular products. In both the systems, cellulose self-assembles into a hierarchical ordered architecture to form micro to nano-fibrillated structures, on basis of which it is classified into various forms. Nanocellulose (NCs) exist as rod-shaped highly crystalline cellulose nanocrystals to high aspect ratio cellulose nanofibers, micro-fibrillated cellulose and bacterial cellulose (BC), depending upon the origin, structural and morphological properties. Moreover, NCs have been processed into diversified products ranging from composite films, coatings, hydrogels, aerogels, xerogels, organogels, rheological modifiers, optically active birefringent colored films using traditional-to-advanced manufacturing techniques. With such versatility in structure-property, NCs have profound application in areas of healthcare, packaging, cosmetics, energy, food, electronics, bioremediation, and biomedicine with promising commercial potential. Herein this review, we highlight the recent advancements in synthesis, fabrication, processing of NCs, with strategic chemical modification routes to tailor its properties for targeted biomedical applications. We also study the basic mechanism and models for biosynthesis of cellulose in both plant and microbial systems and understand the structural insights of NC polymorphism. The kinetics study for both enzymatic/chemical modifications of NCs and microbial growth behavior of BC under various reactor configurations are studied. The challenges associated with the commercial aspects as well as industrial scale production of pristine and functionalized NCs to meet the growing demands of market are discussed and prospective strategies to mitigate them are described. Finally, post chemical modification evaluation of biological and inherent properties of NC are important to determine their efficacy for development of various products and technologies directed for biomedical applications.

Nanocelluloses - Nanotoxicology, Safety Aspects and 3D Bioprinting

Nanocelluloses have good rheological properties that facilitate the extrusion of nanocellulose gels in micro-extrusion systems. It is considered a highly relevant characteristic that makes it possible to use nanocellulose as an ink component for 3D bioprinting purposes. The nanocelluloses assessed in this book chapter include wood nanocellulose (WNC), bacterial nanocellulose (BNC), and tunicate nanocellulose (TNC), which are often assumed to be non-toxic. Depending on various chemical and mechanical processes, both cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) can be obtained from the three mentioned nanocelluloses (WNC, BNC, and TNC). Pre/post-treatment processes (chemical and mechanical) cause modifications regarding surface chemistry and nano-morphology. Hence, it is essential to understand whether physicochemical properties may affect the toxicological profile of nanocelluloses. In this book chapter, we provide an overview of nanotoxicology and safety aspects associated with nanocelluloses. Relevant regulatory requirements are considered. We also discuss hazard assessment strategies based on tiered approaches for safety testing, which can be applied in the early stages of the innovation process. Ensuring the safe development of nanocellulose-based 3D bioprinting products will enable full market use of these sustainable resources throughout their life cycle.

Critical comparison of the properties of cellulose nanofibers produced from softwood and hardwood through enzymatic, chemical and mechanical processes

Current knowledge on the properties of different types of cellulose nanofibers (CNFs) is fragmented. Properties variation is very extensive, depending on raw materials, effectiveness of the treatments to extract the cellulose fraction from the lignocellulosic biomass, pretreatments to facilitate cellulose fibrillation and final mechanical process to separate the microfibrils. Literature offers multiple parameters to characterize the CNFs prepared by different routes. However, there is a lack of an extensive guide to compare the CNFs. In this study, we perform a critical comparison of rheological, compositional, and morphological features of CNFs, produced from the most representative types of woody plants, hardwood and softwood, using different types and intensities of pretreatments, including enzymatic, chemical and mechanical ones, and varying the severity of mechanical treatment focusing on the relationship between macroscopic and microscopic parameters. This structured information will be exceedingly useful to select the most appropriate CNF for a certain application based on the most relevant parameters in each case.

Antimicrobial cellulose hydrogels preparation with RIF loading from bamboo parenchyma cells: A green approach towards wound healing

Wound healing is a challenged and complicated process due to the bacterial infections and frequent replacement in healing process. Hydrogels with properties of visibility and biocompatibility provided convenient and effective treatment during the wound healing process. Bamboo parenchyma cells have a great potential utilized on cellulosic materials fabrication for their high specific surface area and accessibility of chemical reagents. Herein, we present a simple and facile manufacture of transparent wound dressing from bamboo parenchymal cellulose via dissolution in DMAc/LiCl system. Rifampicin (RIF) was loaded on the hydrogel through immersion method. The result exhibited that the maximum drug loading efficiency of cellulose hydrogels was 82.13%. Hydrogel loaded RIF (HLR) showed that the inhibition zones against Gram-negative and Gram-positive bacteria were 19.11 mm and 36.93 mm, respectively. It was observed that the wound was healed more than 60% at 11th day in murine wound models. Meanwhile, RIF provided an exceptionally antibacterial property to hydrogels and promoted proliferation of epidermis cells in wound. As a result of observations, HLR demonstrating potential application in visual wound dressing materials for their excellent transparency, antibacterial effect, wound healing, and biocompatibility.

The effects of cellulose nanocrystal and cellulose nanofiber on the properties of pumpkin starch-based composite films

Pumpkin starch (PS) was extracted from Cucurbita maxima and utilized to prepare films in combination with cellulose nanocrystal (CNC) and cellulose nanofiber (CNF), using a solvent casting strategy. The PS was characterized to contain 26.6% of amylose, exhibiting a "B"-type crystalline structure and high stability against thermal degradation. PS/CNF films showed better thermal stability than PS/CNC films, whereas the CNC was more effective than CNF for enhancing the tensile strength (TS) of the films. The nanocomposite films containing 1% CNC showed the highest TS of 30.32 MPa. Fourier transform infrared spectra revealed stronger hydrogen bonding in the PS/CNC films, likely contributing to the observed high mechanical strength. CNC and CNF both decreased the transparency of PS films, by 5.2% and 13.1%, respectively. Overall, the properties of PS composite films can be effectively modified by incorporating CNC and CNF, as PS/CNC films with high mechanical strength and PS/CNF films with good thermal stability. Our results indicate that PS is a suitable material for CNC/CNF composite film fabrication. These films are expected to be especially useful in food packaging applications.

The comparison of the properties of nanocellulose isolated from colonial and solitary marine tunicates

This is the first comparative of tunicate cellulose nanocrystalline (t-CNC) from colonial and solitary tunicates. The t-CNC from the colonial tunicate Eudistoma sp. (CL1) was compared with solitary tunicates Polycarpa reniformis (CL2) and Phallusia nigra (CL3). Tunicate samples were extracted by methanol. Residues from the methanol extraction were then subjected to further cellulose purification using pre-hydrolysis, kraft-cooking, bleaching, and sulfuric acid hydrolysis to yield t-CNC. The solitary tunicates yielded higher microfibril contents after the bleaching step but obtained similar t-CNC content to the colonial one after acid hydrolysis. The isolated t-CNC were characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermalgravimetric analysis, and transmission electron microscopy. Both colonial and solitary tunicates yielded cellulose type I. The pure cellulose type I was successfully isolated from solitary tunicates whereas high inorganic impurities were observed in colonial tunicates. The isolate t-CNC showed high aspect ratios. The solitary and colonial tunicates provided t-CNC with crystallinity indexes over 97% and 35%, respectively. The crystalline size of t-CNCs ranged from 55-124 Å. The thermal stability of all isolated t-CNC was slightly decreased due to the sulfate functional groups gained after acid hydrolysis. We concluded that solitary tunicates were better than colonial tunicates as a source of t-CNC preparation.

Functional Nanocellulose, Alginate and Chitosan Nanocomposites Designed as Active Film Packaging Materials

The aim of the study was to characterize and compare films made of cellulose nanocrystals (CNC), nano-fibrils (CNF), and bacterial nanocellulose (BNC) in combination with chitosan and alginate in terms of applicability for potential food packaging applications. In total, 25 different formulations were made and evaluated, and seven biopolymer films with the best mechanical performance (tensile strength, strain)—alginate, alginate with 5% CNC, chitosan, chitosan with 3% CNC, BNC with and without glycerol, and CNF with glycerol—were selected and investigated regarding morphology (SEM), density, contact angle, surface energy, water absorption, and oxygen and water barrier properties. Studies revealed that polysaccharide-based films with added CNC are the most suitable for packaging purposes, and better dispersing of nanocellulose in chitosan than in alginate was observed. Results showed an increase in hydrophobicity (increase of contact angle and reduced moisture absorption) of chitosan and alginate films with the addition of CNC, and chitosan with 3% CNC had the highest contact angle, 108 ± 2, and 15% lower moisture absorption compared to pure chitosan. Overall, the ability of nanocellulose additives to preserve the structure and function of chitosan and alginate materials in a humid environment was convincingly demonstrated. Barrier properties were improved by combining the biopolymers, and water vapor transmission rate (WVTR) was reduced by 15–45% and oxygen permeability (OTR) up to 45% by adding nanocellulose compared to single biopolymer formulations. It was concluded that with a good oxygen barrier, a water barrier that is comparable to PLA, and good mechanical properties, biopolymer films would be a good alternative to conventional plastic packaging used for ready-to-eat foods with short storage time.

Vascularization of tissue engineered cartilage - Sequential in vivo MRI display functional blood circulation

Establishing functional circulation in bioengineered tissue after implantation is vital for the delivery of oxygen and nutrients to the cells. Native cartilage is avascular and thrives on diffusion, which in turn depends on proximity to circulation. Here, we investigate whether a gridded three-dimensional (3D) bioprinted construct would allow ingrowth of blood vessels and thus prove a functional concept for vascularization of bioengineered tissue. Twenty 10 × 10 × 3-mm 3Dbioprinted nanocellulose constructs containing human nasal chondrocytes or cell-free controls were subcutaneously implanted in 20 nude mice. Over the next 3 months, the mice were sequentially imaged with a 7 T small-animal MRI system, and the diffusion and perfusion parameters were analyzed. The chondrocytes survived and proliferated, and the shape of the constructs was well preserved. The diffusion coefficient was high and well preserved over time. The perfusion and diffusion patterns shown by MRI suggested that blood vessels develop over time in the 3D bioprinted constructs; the vessels were confirmed by histology and immunohistochemistry. We conclude that 3D bioprinted tissue with a gridded structure allows ingrowth of blood vessels and has the potential to be vascularized from the host. This is an essential step to take bioengineered tissue from the bench to clinical practice.

Approaches in Animal Proteins and Natural Polysaccharides Application for Food Packaging: Edible Film Production and Quality Estimation

Natural biopolymers are an interesting resource for edible films production, as they are environmentally friendly packaging materials. The possibilities of the application of main animal proteins and natural polysaccharides are considered in the review, including the sources, structure, and limitations of usage. The main ways for overcoming the limitations caused by the physico-chemical properties of biopolymers are also discussed, including composites approaches, plasticizers, and the addition of crosslinking agents. Approaches for the production of biopolymer-based films and coatings are classified according to wet and dried processes and considered depending on biopolymer types. The methods for mechanical, physico-chemical, hydration, and uniformity estimation of edible films are reviewed.

Facile preparation of all-cellulose composites from softwood, hardwood, and agricultural straw cellulose by a simple route of partial dissolution

In this study, we report a novel, facile, and green method that was used for creating a new all-cellulose composite (ACC) based on inorganic molten salt solvent. Three representatively native fibers from softwood (Pinus kesiya), hardwood (Eucalyptus globulus), and agricultural straw (Zea mays) were selected to verify the effect of the method. The welded sheets were thoroughly characterized and compared. Cellulose sheets from the pine exhibited excellent mechanical properties (σb 16.94 MPa) and thermal stability (T_max 265 °C) after the welding process, while the corn stalk sheets displayed more robust and thermostable features than the eucalyptus. The welding technique using inorganic metal salt hydrate provides a promising and convenient route to obtain firm sheet-materials with micro- or nano-structures from nature fibers.

Highly efficient synthesis of biodiesel catalyzed by a cellulose@hematite-zirconia nanocomposite

The depletion of fossil fuels calls for the development of renewable alternatives such as biodiesel and has inspired much research on catalysts for the production of biodiesel through the esterification of biomass-derived materials. Herein, a green heterogeneous catalyst for highly efficient biodiesel synthesis was fabricated from rice straw-derived cellulose, hematite, and zirconia and was shown to contain porous irregularly shaped α-Fe2O3-ZrO2 composites (average particle size = 42.5 nm) evenly distributed on the nanocellulose surface. The optimal catalyst (nanocellulose:α-Fe2O3-ZrO2 = 2:1, w/w) afforded biodiesel in a yield of 92.50% and with specifications close to those prescribed by international standards. This catalyst could be reused for up to five cycles without a marked activity loss, with the biodiesel yield in the fifth cycle equaling 80.0%. The developed nanocomposite holds great promise for cutting the costs of biodiesel production, as it is derived from biodegradable raw materials and is renewable, non-corrosive, easy to handle, and green. In addition, the large-scale discharge of this catalyst after use does not pose a hazard to the environment.

Micro- and nano-structures of cellulose from eggplant plant (Solanum melongena L) agricultural residue

Currently, agriculture sector produces enormous quantity of residues, creating severe environmental problems. These agricultural residues are rich in lignocellulosic fibers, making them sustainable sources to produce high added-value materials. This investigation aims to transform the eggplant plant residue (EPR) into purified cellulose microfibers (CMF) and cellulose nanocrystals (CNC). CMF with a yield of 54 %, diameter of 13.6 μm and crystallinity of 71 % were successfully obtained from raw EPR using alkali and bleaching treatments. By subjecting CMF to phosphoric and sulfuric acid hydrolysis, phosphorylated (P-CNC) and sulfated (S-CNC) were produced. P-CNC and S-CNC exhibited an aspect ratio of 89.4 and 74.2, zeta potential value of - 39.4 and - 28.7 mV, surface charge density of 116.7 and 218.2 mmol/kg cellulose and a crystallinity of 73 % and 80 %, respectively. Herein, the obtained cellulosic structures with excellent properties could be used in various applications, such as bio-derived fillers for polymer composites development.

Electrostatic Interaction-Controlled Formation of Pickering Emulsion for Continuous Flow Catalysis

Although noble metal or non-noble metal-catalyzed reactions are widely used, it is still difficult to apply these reactions in the large-scale synthesis of chemicals because most of the reactions are carried out by the inefficient batch reaction strategy. Herein, Pickering emulsion-based continuous flow catalysis was utilized to address this problem. Cellulose nanofibers with aldehyde groups (ACNF) were generated through oxidizing C2 and C3 hydroxyl groups of cellulose nanofibers into aldehyde groups by NaIO₄, followed by in situ depositing Ag nanoparticles on ACNF to produce Ag-decorated ACNF (ACNF@Ag) via a facile aldehyde-induced reduction method. ACNF@Ag with ∼2 wt % Ag (ACNF@Ag2) has been used to prepare the Pickering emulsion by controlling the electrostatic interaction between ACNF@Ag2 and the oil-water interface via adjusting the pH. It was found that the Pickering emulsion could be generated at a pH around 3.29 and was determined to be the oil-in-water emulsion. The reduction of organic molecules (4-nitrophenol (4-NP), methylene blue (MB), and methyl orange (MO)) was selected as a model reaction to test the reliability of the Pickering emulsion in continuous flow catalysis, which demonstrated very high conversion rates for 4-NP (>98%, 50 h), MB (>99%, 30 h), and MO (>96%, 40 h).

Study on the Anti-Biodegradation Property of Tunicate Cellulose

Tunicate is a kind of marine animal, and its outer sheath consists of almost pure Iβ crystalline cellulose. Due to its high aspect ratio, tunicate cellulose has excellent physical properties. It draws extensive attention in the construction of robust functional materials. However, there is little research on its biological activity. In this study, cellulose enzymatic hydrolysis was conducted on tunicate cellulose. During the hydrolysis, the crystalline behaviors, i.e., crystallinity index (CrI), crystalline size and degree of polymerization (DP), were analyzed on the tunicate cellulose. As comparisons, similar hydrolyses were performed on cellulose samples with relatively low CrI, namely α-cellulose and amorphous cellulose. The results showed that the CrI of tunicate cellulose and α-cellulose was 93.9% and 70.9%, respectively; and after 96 h of hydrolysis, the crystallinity, crystalline size and DP remained constant on the tunicate cellulose, and the cellulose conversion rate was below 7.8%. While the crystalline structure of α-cellulose was significantly damaged and the cellulose conversion rate exceeded 83.8% at the end of 72 h hydrolysis, the amorphous cellulose was completely converted to glucose after 7 h hydrolysis, and the DP decreased about 27.9%. In addition, tunicate cellulose has high anti-mold abilities, owing to its highly crystalized Iβ lattice. It can be concluded that tunicate cellulose has significant resistance to enzymatic hydrolysis and could be potentially applied as anti-biodegradation materials.

Nanocomposites derived from licorice residues cellulose nanofibril and chitosan nanofibril: Effects of chitosan nanofibril dosage on resultant properties

Research on nanocomposite film from natural polymers such as cellulose and chitosan is of great importance to promote the development and highly efficient utilization of green and renewable bioresources. In this study, enzymatic pretreatment cellulose nanofibril (ETCNF) derived from licorice residues was prepared, and further processed into nanocomposite film with addition of chitosan nanofibril (CHN). This study focused on the effects of CHN dosage on the main properties of resultant nanocomposite film in terms of crystallinity, thermal stability, light transmittance, hydrophobicity, mechanical properties, and antibacterial activity. The results showed that ETCNF/CHN nanocomposite film exhibited good hydrophobicity especially at higher dosage of CHN, good light transmittance and mechanical properties (tensile strain can reach 39.6 MPa for ETCNF/CHN-10.0%). The as-prepared ETCNF/CHN nanocomposite film also showed good antibacterial activity against Escherichia coli. It was expected that the ETCNF/CHN nanocomposite film would help to realize transformation and high value-added utilization of these biomass residues.

High crystallinity of tunicate cellulose nanofibers for high-performance engineering films

Tunicate cellulose nanofibers (CNFs) have received widespread attention as renewable and eco-friendly engineering materials because of their high crystallinity and mechanical stiffness. Here, we report the effects of disintegration process conditions on structure-property relationships of tunicate CNFs. By varying the hydrolysis time, we could establish a correlation between crystallinity of the CNFs with linearity and stiffness, which produces different molecular ordering within their nanostructured films. Despite having identical raw materials, tensile strength and thermal conductivity of the resulting layered films varied widely, ranging from 95.6 to 205 MPa and from 1.08 to 2.37 W/mK respectively. Furthermore, nanolayered CNF films provided highly anisotropic thermal conductivities with an in- and through-plane ratio of 21.5. Our systematic investigations will provide general and practical strategies in tailoring material properties for emerging engineering applications, including flexible paper electronics, heat sink adhesives and biodegradable, implantable devices.