Pickering Emulsions and Hydrophobized Films of Amphiphilic Cellulose Nanofibers Synthesized in Deep Eutectic Solvent.

Herein, a dual-functioning deep eutectic solvent system based on triethylmethylammonium chloride and imidazole was harnessed as a swelling agent and a reaction medium for the esterification of cellulose with n-octyl succinic anhydride (OSA). The modified or amphiphilic cellulose nanofibers (ACNFs), synthesized using three different OSA-to-anhydroglucose unit molar ratios (0.5:1, ACNF-1; 1:1, ACNF-2; and 1.5:1, ACNF-3), were further converted into nanofibers with degree of substitution (DS) values of 0.24-0.66. The ACNFs possessed a lateral dimension of 4.24-9.22 nm and displayed surface activity due to the balance of hydrophobic and hydrophilic characteristics. The ACNFs made stable aqueous dispersions; however, the instability index of ACNF-3 (0.51) was higher than those of ACNF-1 (0.29) and ACNF-2 (0.33), which was attributed to the high DS-induced hydrophobicity, causing the instability in water. The amphiphilic nature of ACNFs promoted their performance as stabilizers in oil-in-water Pickering emulsions with average droplet sizes of 4.85 µm (ACNF-1) and 5.48 µm (ACNF-2). Self-standing films of ACNFs showed high contact angles for all the tested DS variants (97.48-114.12°), while their tensile strength was inversely related to DS values (ACNF-1: 115 MPa and ACNF-3: 49.5 MPa). Aqueous dispersions of ACNFs were also tested for coating fruits to increase their shelf life. Coatings improved their shelf life by decreasing oxygen contact and moisture loss.

Role of silica-based porous cellulose nanocrystals in improving water absorption and mechanical properties.

Epoxy resins are important thermosetting polymers. They are widely used in many applications i.e., adhesives, plastics, coatings and sealers. Epoxy molding compounds have attained dominance among common materials due to their excellent mechanical properties. The sol-gel simple method was applied to distinguish the impact on the colloidal time. The properties were obtained with silica-based fillers to enable their mechanical and thermal improvement. The work which we have done here on epoxy-based nanocomposites was successfully modified. The purpose of this research was to look into the effects of cellulose nanocrystals (CNCs) on various properties and applications. CNCs have recently attracted a lot of interest in a variety of industries due to their high aspect ratio, and low density which makes them perfect candidates. Adding different amounts of silica-based nanocomposites to the epoxy system. Analyzed with different techniques such as Fourier-transformed infrared spectroscope (FTIR), thermogravimetric analysis (TGA) and scanning electronic microscopic (SEM) to investigate the morphological properties of modified composites. The various %-age of silica composite was prepared in the epoxy system. The 20% of silica was shown greater enhancement and improvement. They show a better result than D-400 epoxy. Increasing the silica, the transparency of the films decreased, because clustering appears. This shows that the broad use of CNCs in environmental engineering applications is possible, particularly for surface modification, which was evaluated for qualities such as absorption and chemical resistant behavior.

SCOBY Cellulose Modified with Apple Powder-Biomaterial with Functional Characteristics.

The need for new non-animal and non-petroleum-based materials is strongly emphasized in the sustainable and green economy. Waste materials have proven a valuable resource in this regard. In fact, there have been quite a large number of goods obtained from wastes called "Vegan leather" that have gained the clothing market's attention in recent years. In practice, they are mostly composites of waste materials like cactus, pineapples, or, eventually, apples with polymers like polyurethane or polyvinyl chloride. The article presents the results of work aimed at obtaining a material based entirely on natural, biodegradable raw materials. Bacterial cellulose produced as a byproduct of the fermentation carried out by SCOBY was modified with glycerol and then altered by the entrapment of apple powder. The effect of introducing apple powder into the SCOBY culture media on the mechanical properties of the obtained bacterial cellulose was also evaluated The resulting material acquired new mechanical characteristics that are advantageous in terms of strength. Microscopic observation of the apple powder layer showed that the coverage was uniform. Different amounts of apple powder were used to cover the cellulose surface from 10 to 60%, and it was found that the variant with 40% of this powder was the most favorable in terms of mechanical strength. Also, the application of the created material as a card folder showed that it is durable in use and retains its functional characteristics for at least 1 month. The mechanical properties of modified bacterial cellulose were favorably affected by the entrapment of apple powder on its surface, and as a result, a novel material with functional characteristics was obtained.

Fast Response and Visual Transparency Switching Hydrochromic Film Based on the Rational Structure of Cellulose/Poloxamer Copolymers Design for Smart Window.

The authors are motivated to develop a series of hydrochromic copolymers with fast response, reversibility, repeatability, and visual transparency transition. The hydrochromic block copolymers are based on the rational ratio of hydrophilic segments of poloxamer block and hydrophobic segments of ethyl cellulose according to the preparation method of polyurethane. By tuning the ratio of hydrophilic segments or adding hygroscopic salts, the hydrochromic polymer is endowed with the ability to visualize the transparency in response to the relative humidity. Especially, the response time of the polymer is extremely shortened, up to 1 s for the optimized sample. Within the moisture stimulation, the hygroscopic swelling increases the film thickness, leading to a reversible transparency switching from a highly transparent state (82%) to an opaque white state (20.5%).

Highly efficient microencapsulation of phytonutrients by fractioned cellulose using biopolymer complexation technology.

A poorly water soluble polar and non-polar bioactive complexes encapsulated in a nanocellulose-based polymeric network are the focus of this research. Ascorbic acid, resveratrol, holy basil extract, pomegranate extract, and niacin are all microencapsulated bioactive complexes that make up Zetalife®, a nutritional ingredient. It uses an interpenetrating polymeric network (IPN) with more dispersed nanocellulose and phospholipids to increase Zetalife® s bioavailability. Field Emission Scanning Electron Microscopic (FESEM) images were used in studying the morphology of encapsulated bioactive molecules. The average microbead size was determined to be 244.2 nm. After each month of storage, the sample's microbial content was measured to assess stability. In vitro release followed a first-order kinetic model with high R2.

Synthesis and Characterization of Cellulose Triacetate Obtained from Date Palm (Phoenix dactylifera L.) Trunk Mesh-Derived Cellulose.

Cellulosic polysaccharides have increasingly been recognized as a viable substitute for the depleting petro-based feedstock due to numerous modification options for obtaining a plethora of bio-based materials. In this study, cellulose triacetate was synthesized from pure cellulose obtained from the waste lignocellulosic part of date palm (Phoenix dactylifera L.). To achieve a degree of substitution (DS) of the hydroxyl group of 2.9, a heterogeneous acetylation reaction was carried out with acetic anhydride as an acetyl donor. The obtained cellulose ester was compared with a commercially available derivative and characterized using various analytical methods. This cellulose triacetate contains approximately 43.9% acetyl and has a molecular weight of 205,102 g·mol-1. The maximum thermal decomposition temperature of acetate was found to be 380 °C, similar to that of a reference sample. Thus, the synthesized ester derivate can be suitable for fabricating biodegradable and "all cellulose" biocomposite systems.

Surface Modification of Bacterial Cellulose for Biomedical Applications.

Bacterial cellulose is a naturally occurring polysaccharide with numerous biomedical applications that range from drug delivery platforms to tissue engineering strategies. BC possesses remarkable biocompatibility, microstructure, and mechanical properties that resemble native human tissues, making it suitable for the replacement of damaged or injured tissues. In this review, we will discuss the structure and mechanical properties of the BC and summarize the techniques used to characterize these properties. We will also discuss the functionalization of BC to yield nanocomposites and the surface modification of BC by plasma and irradiation-based methods to fabricate materials with improved functionalities such as bactericidal capabilities.

Characterization of potential cellulose fiber from cattail fiber: A study on micro/nano structure and other properties.

Exploration of the application prospects of cattail fibers (CFs) in natural composites, and other fields is important for the sustainable development of new, green, light-weight, functional biomass materials. In this study, the physical and chemical properties, micro/nano structure, and mechanical characteristics of CFs were investigated. The CFs have a low density (618.0 kg m-3). The results of transmission electron microscopy and tensile testing data indicated that the cattail trunk fiber (CTF) bundle is composed of parenchyma cells and solid stone cells, demonstrating high specific modulus (10.1 MPa∙m3·kg-1) and high elongation at break (3.9%). In turn, the cattail branch fiber (CBF) bundle is composed of parenchyma cells with specific "half-honeycomb" shape. The inner diaphragms divide these cells into the open cavities. This structural feature endows the CTF bundles with stable structure, good oil absorption and storage capacities. The chemical component and the Fourier transform infrared spectroscopy analyses show that the CFs have higher lignin content (20.6%) and wax content (11.5%), which are conducive to the improvement of corrosion resistance, thermal stability and lipophilic-hydrophobic property of CF. Finally, the thermogravimetric analysis indicates that its final degradation temperature is 404.5 °C, which is beneficial to the increase in processability of CFs-reinforced composites.

ZnO nanoparticles stabilized oregano essential oil Pickering emulsion for functional cellulose nanofibrils packaging films with antimicrobial and antioxidant activity.

The growth and reproduction of microorganisms can cause food spoilage in the process of food transportation and storage. Active packaging is a good way to inhibit food spoilage and prolong the shelf lives of foods. In this study, O/W Pickering emulsion with ZnO nanoparticles as solid particles and oregano essential oil as the oil phase was prepared and used to functionalize cellulose nanofibrils (CNFs) film, and excellent antimicrobial and antioxidant activity was obtained. When the concentration of ZnO nanoparticles was 1.5 wt% and the mass fraction of the oil phase was 20%, the Pickering emulsion with a particle size of 26.85 µm exhibited strong standing stability. The Pickering emulsion was blended with the film-forming matrix CNFs to prepare active packaging films by casting. The Pickering emulsion evenly dispersed in the film to form microcapsules which encapsulated oregano essential oil entirely. The antimicrobial activity against Listeria monocytogenes was 89.61%, the DPPH radical scavenging rate was 58.52%, while the barrier properties of the developed films against oxygen, water vapor and visible light were improved. The active CNFs film prepared by Pickering emulsion could inhibit the growth of microorganism and prolong the shelf lives of foods.

Effects of pretreatment, NaOH concentration, and extraction temperature on the cellulose from Lophatherum gracile Brongn.

Lophatherum gracile Brongn. (LGB), a homology material of medicine and food, has plentiful cellulose. Aiming to investigate the physiochemical characteristic differences of LGB cellulose extracted by various pretreatment methods and extraction conditions, the effect of dry crushing and wet beating, and the alkaline solution concentration and temperature were compared. Results showed that the extracted cellulose after dry crushing pretreatment had higher purity and lower non-cellulosic components such as hemicellulose, lignin and ash than those obtained by wet beating pretreatment. Furthermore, the impurities were more thoroughly removed by the alkaline solution at high concentration and temperature. Structural characterization revealed that the cellulose obtained by wet beating pretreatment had more fibrillation and smaller particle size, while destroyed crystallinity resulting in bad thermal stability. The alkaline solution temperature had no effect on the morphology and particle size, but high alkaline solution temperature (90 °C) improved crystallinity and thermal stability. Furtherly, the cellulose II produced by at high alkaline solution concentration (18 wt%) exhibited denser surface, smaller particle size and higher thermal stability than the cellulose I extracted at low alkaline solution concentration (4 wt%). Especially, the crystallinity of cellulose II was higher than that of cellulose I with dry crushing pretreatment, while the cellulose obtained by wet beating displayed an opposite trend. Hydration properties indicated that the water holding capacity, oil binding capacity and swelling capacity of the cellulose pretreated by dry crushing were higher than those of the cellulose pretreated by wet beating, and the cellulose I exhibited higher hydration properties compared to the cellulose II, which may depend on its loose network structure. This study suggested that dry crushing pretreatment and high alkaline solution temperature could effectively improve functional properties of LGB cellulose I and II, which promoted its use in food applications.

Valorization of Byproducts of Hemp Multipurpose Crop: Short Non-Aligned Bast Fibers as a Source of Nanocellulose.

Nanocellulose was extracted from short bast fibers, from hemp (Cannabis sativa L.) plants harvested at seed maturity, non-retted, and mechanically decorticated in a defibering apparatus, giving non-aligned fibers. A chemical pretreatment with NaOH and HCl allowed the removal of most of the non-cellulosic components of the fibers. No bleaching was performed. The chemically pretreated fibers were then refined in a beater and treated with a cellulase enzyme, followed by mechanical defibrillation in an ultrafine friction grinder. The fibers were characterized by microscopy, infrared spectroscopy, thermogravimetric analysis and X-ray diffraction after each step of the process to understand the evolution of their morphology and composition. The obtained nanocellulose suspension was composed of short nanofibrils with widths of 5-12 nm, stacks of nanofibrils with widths of 20-200 nm, and some larger fibers. The crystallinity index was found to increase from 74% for the raw fibers to 80% for the nanocellulose. The nanocellulose retained a yellowish color, indicating the presence of some residual lignin. The properties of the nanopaper prepared with the hemp nanocellulose were similar to those of nanopapers prepared with wood pulp-derived rod-like nanofibrils.

Preparation and characterization of antibacterial bacterial cellulose/chitosan hydrogels impregnated with silver sulfadiazine.

Hydrogels with pH sensitivity and stable mechanical and antibacterial properties have many desirable qualities and broad applications. A hydrogel based on bacterial cellulose and chitosan, impregnated with silver sulfadiazine (<1% w/w), was prepared using glutaraldehyde as the crosslinking agent. The presence of SSd was confirmed by Fourier transform infrared spectroscopy. Micropore size, swelling ratio, pH- sensitivity, and gram positive and negative antibacterial properties were studied by disk diffusion and colony forming unit. X-ray diffraction confirmed the presence of amorphous and crystalline regions in the hydrogel matrix following addition of SSd. The elemental composition, morphology, and mechanical properties of the hydrogels were characterized. Incorporation of SSd into bacterial cellulose-chitosan hydrogels significantly improved their mechanical and antibacterial properties. The antibacterial activity against E. coli and S. aureus was evaluated and SSd-BC/Ch hydrogels are more toxic to S. aureus than to E. coli. We use FESEM to observe bacterial morphology before and after exposure to SSd-BC/Ch hydrogels. The BacLight LIVE/DEAD membrane permeability kit is used to evaluate the membrane permeability of bacteria. These antibacterial hydrogels have many promising applications in food packaging, tissue engineering, drug delivery, clinical, biotechnological, and biomedical fields.

Production of bacterial cellulose tubes for biomedical applications: Analysis of the effect of fermentation time on selected properties.

Biosynthesis of bacterial cellulose (BC) in cylindrical oxygen permeable molds allows the production of hollow tubular structures of increasing interest for biomedical applications (artificial blood vessels, ureters, urethra, trachea, esophagus, etc.). In the current contribution a simple set-up is used to obtain BC tubes of predefined dimensions; and the effects of fermentation time on the water holding capacity, nanofibrils network architecture, specific surface area, chemical purity, thermal stability, mechanical properties, and cell adhesion, proliferation and migration of BC tubes are systematically analysed for the first time. The results reported highlight the role of culture time on key properties of the BC tubes produced, with significant differences arising from the denser and more compact fibril arrangements generated at longer fermentation intervals.

Fabrication of Paper Sheets Coatings Based on Chitosan/Bacterial Nanocellulose/ZnO with Enhanced Antibacterial and Mechanical Properties.

Here, we designed paper sheets coated with chitosan, bacterial cellulose (nanofibers), and ZnO with boosted antibacterial and mechanical activity. We investigated the compositions, with ZnO exhibiting two different sizes/shapes: (1) rods and (2) irregular sphere-like particles. The proposed processing of bacterial cellulose resulted in the formation of nanofibers. Antimicrobial behavior was tested using E. coli ATCC® 25922™ following the ASTM E2149-13a standard. The mechanical properties of the paper sheets were measured by comparing tearing resistance, tensile strength, and bursting strength according to the ISO 5270 standard. The results showed an increased antibacterial response (assigned to the combination of chitosan and ZnO, independent of its shape and size) and boosted mechanical properties. Therefore, the proposed composition is an interesting multifunctional mixture for coatings in food packaging applications.

Cytocompatible cellulose nanofibers from invasive plant species Agave americana L. and Ricinus communis L.: a renewable green source of highly crystalline nanocellulose.

In this study, the fibers of invasive species Agave americana L. and Ricinus communis L. were successfully used for the first time as new sources to produce cytocompatible and highly crystalline cellulose nanofibers. Cellulose nanofibers were obtained by two methods, based on either alkaline or acid hydrolysis. The morphology, chemical composition, and crystallinity of the obtained materials were characterized by scanning electron microscopy (SEM) together with energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. The crystallinity indexes (CIs) of the cellulose nanofibers extracted from A. americana and R. communis were very high (94.1% and 92.7%, respectively). Biological studies evaluating the cytotoxic effects of the prepared cellulose nanofibers on human embryonic kidney 293T (HEK293T) cells were also performed. The nanofibers obtained using the two different extraction methods were all shown to be cytocompatible in the concentration range assayed (i.e., 0|‒|500 µg/mL). Our results showed that the nanocellulose extracted from A. americana and R. communis fibers has high potential as a new renewable green source of highly crystalline cellulose-based cytocompatible nanomaterials for biomedical applications.

Preparation and characterization of air nanofilters based on cellulose nanofibers.

One of the most important environmental issues in the world today is the problem of air pollution, which includes particulate matter (PM) and greenhouse gases (mainly CO2). The production of efficient sustainable filters to overcome this concern as well as to provide an alternative to synthetic petroleum-based filters remains a demanding challenge. The purpose of this research was to first produce novel cellulose nanofibers (CNF) based nanofilter from a combination of CNF and chitosan (CS) and then evaluate its applicability for air purification. A number of structural and chemical properties as well as CO2 and PM adsorption efficiency of the modified CNF, were determined using advanced characterization techniques. After pretests, we determined the optimum loading for the CS was 1 wt%, and upon producing the samples, the CNF loadings (1, 1.5, and 2 wt%) were chosen as one variable. For particle absorption, the PM sizes (0.1, 0.3, 0.5, and 2.5 µm) were kept as other variables. Based on SEM results, we concluded the higher the concentration of CNF the higher the specific surface area and the lower the porosity and the diameter of the pores, which was confirmed by the BET test. Furthermore, the results showed that increasing the concentration of modified CNFs increases the adsorption rate of CO2 and PM and that the highest adsorption of CO2 and PM belonged to the 2% modified CNF.

Preparation of cellulose nanospheres via combining ZnCl2·3H2O pretreatment and p-toluenesulfonic hydrolysis as a two-step method.

Spherical nanocelluloses, also known as cellulose nanospheres (CNS), have controllable morphology and have shown advantages as green template material, emulsion stabilizer. Herein, CNS were prepared via a new two-step method, first pretreatment of microcrystalline cellulose (MCC) using ZnCl2·3H2O and then acid hydrolysis of regenerated cellulose (RC) via p-toluenesulfonic acid (p-TsOH). The shape, size, crystallinity of MCC were changed, and nubbly RC with smallest size (942 nm) was obtained after 2 h pretreatment by ZnCl2·3H2O. CNS with high 61.3% yield were produced after acid hydrolysis (67 wt% p-TsOH) of RC at 80 °C, 6 h. The analysis of Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM) showed that CNS had an average diameter of 347 nm. CNS were present in precipitate after high-speed centrifugation, due to the high Zeta potential of -12 mV and large size. The structure of CNS was tested by Fourier Transfer Infrared Spectroscopy (FTIR), X-ray Diffraction (XRD), Nuclear Magnetic Resonance (NMR), CNS had high crystallinity (cellulose II) of 61%. Thermal Gravimetric Analysis (TGA) indicated that CNS had high thermal stability (Tonset 303.3 °C, Tmax 332 °C). CNS showed poor re-dispersibility in water/ethanol/THF, 1 wt% CNS could be dissolved in ZnCl2·3H2O. 7.37% rod-like CNC were obtained after 6 h hydrolysis. FTIR proved that p-TsOH was recovered by re-crystallization. This study provided a novel, sustainable two-step method for the preparation of spherical CNS.

Cellulose derivatives agglomerated in a fluidized bed: Physical, rheological, and structural properties.

Understanding the agglomeration of cellulose derivatives is crucial for the production of instant gum-based food thickeners. In the present study, physical, rheological, and structural properties of agglomerated water-soluble cellulose gums (CGs), such as carboxymethylcellulose (CMC), hydroxypropylmethylcellulose (HPMC), and methylcellulose (MC), were investigated at different concentrations of maltodextrin (MD) as a binder for fluidized-bed agglomeration. Among the CG agglomerates in the presence of MD, CMC exhibited better flowability and lower cohesiveness, showing lower Carr index and Hausner ratio values. The MC agglomerates with 20% MD exhibited higher porosity than the other CGs due to the size enlargement of MC particles, which was confirmed via scanning electron microscopy images and size distribution profiles. The dynamic moduli of the CG agglomerates were significantly decreased by the addition of MD and also decreased with increasing MD concentration. The tan δ values of the agglomerates increased with increasing MD concentration, indicating the enhancement of their viscous properties. These results suggest that the physical, rheological, and structural properties of cellulose derivatives with different types of CG can be greatly influenced by their agglomerate growths during fluidized-bed agglomeration of particles with the different concentrations of MD binder.

Porous carboxymethyl cellulose carbon of lignocellulosic based materials incorporated manganese oxide for supercapacitor application.

The present work developed porous carboxymethyl cellulose (CMC) carbon film from lignocellulosic based materials as supercapacitor electrode. Porous CMC carbon films of bamboo (B) and oil palm empty fruit bunch (O) were prepared through simple incipient wetness impregnation method followed by calcination process before incorporation with manganese oxide (Mn2O3). The carbonization produced porous CMC carbon whereby CMCB exhibited higher surface area than CMCO. After Mn2O3 incorporation, the crystallite size of CMCB and CMCO were calculated as 50.09 nm and 42.76 nm, respectively whereas Mn2O3/CMCB and Mn2O3/CMCO composite films were revealed to be 26.71 nm and 35.60 nm in size, respectively. Comparatively, the Mn2O3/CMCB composite film exhibited higher electrochemical performance which was 31.98 mF cm-2 as compared to 24.15 mF cm-2 by Mn2O3/CMCO composite film and both CMC carbon films with fairly stable cycling stability after 1000 charge-discharge cycles. Therefore, it can be highlighted that Mn2O3/CMC composite film as prepared from bamboo and oil palm fruit can potentially become the new electrode materials for supercapacitor application.

Nanocellulose as template to prepare rough-hydroxy rich hollow silicon mesoporous nanospheres (R-nCHMSNs) for drug delivery.

Drug-delivery technology is an effective way to promote drug absorption and efficacy. Mesoporous hollow silica material and small-molecule drug ibuprofen were used as a carrier model and as model drug, respectively. By quantum chemical calculation (density functional theory and frontier orbital theory), it was found that the content of geminal silanols on the material surface played a decisive role in the release of the different drugs. The rough hollow materials are easily adsorbed and have a large loading capacity, and so we fabricated a mesoporous hollow silica material (R-nCHMSNs) with a rough surface and rich geminal silanols by using hydroxyl-rich nanocellulose as a template. The content and types of hydroxyl groups on the material surface were studied by 29Si NMR. The loading and delivery of ibuprofen and lysozyme were studied in detail. Materials with rich geminal silanols exhibited excellent delivery properties for different drugs, which shows great potential and research value for drug delivery.