Cellulose Nanofibers Research Articles

Ultralight Cellulose-Derived Carbon Nanofibers from Freeze-Drying Emulsion Towards Superior Microwave Absorption

Carbon nanofibers (CNFs) are usually prepared by the carbonization of cellulose aerogels obtained from freeze-drying. However, cellulose with low concentration (below 1 wt%) is required to maintain the good porosity of the aerogels due to the strong hydrogen bonding between the cellulose molecules. In order to address this problem, here, ultralight cellulose-derived CNFs have been fabricated by freeze-drying cyclohexane (CHE)/cellulose nanofiber emulsions and carbonization. Field emission scanning electron microscopy, Raman spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy are used to characterize the resulting CNFs. It is found that the CNFs consist of three-dimensional carbon networks, whose microstructure is easily adjusted by changing the CHE ratio (from 0 to 25 vol%) in the emulsions. The CNFs with high porosity are attributed to the fact that CHE as the oil phase can effectively weaken the hydrogen bonding and reduce the aggregation of the cellulose nanofibers. Carbon lattice defects and residual oxygen-containing functional groups are regarded as polarization centers, leading to the enhancement of dielectric loss. The conductive carbon networks also improve the conductive loss. All these factors improve the microwave absorption performance of the CNFs. So, the produced CNFs exhibit a superior electromagnetic wave performance with a minimum reflection loss of −42.18 dB and effective absorption bandwidth up to 4.9 GHz at 2 mm with a filling ratio of 2 wt%. This work provides a simple, low-cost, and sustainable synthesis route for CNFs used for ultralight high-performance microwave absorption materials.

Low-Cost Hyperelastic Fuller-Dome-Structured Nanocellulose Aerogels by Dual Templates for Personal Thermal Management.

It is critically important to maintain the body's thermal comfort for human beings in extremely cold environments. Cellulose nanofibers (CNF)-based aerogels represent a promising sustainable material for body's heat retention because of their renewability and low thermal conductivity. However, CNF-based aerogels often suffer high production costs due to expensive CNF, poor elasticity and/or unsatisfactory thermal insulation owing to improper microstructure design. Here, a facile dual-template strategy is reported to prepare a low-cost, hyperelastic, superhydrophobic Fuller-dome-structured CNF aerogel (CNF@PU) with low thermal conductivity. The combination of air template by foaming process and ice template enables the formation of a dome-like microstructure of CNF@PU aerogel, in which CNF serves as rope bars while inexpensive polyurethane (PU) acts as joints. The aerogel combines ultra-elasticity, low thermal conductivity (24mW m-1 K-1), and low costs. The as-prepared CNF@PU aerogel demonstrates much better heat retention than commercial thermal retention fillers (e.g., Flannelette and goose down), promising its great commercial potential for massively producing warming garments. This work provides a facile approach for creating high-performance aerogels with tailored microstructure for effective personal thermal management.

Characterization of MSC Growth, Differentiation, and EV Production in CNF Hydrogels Under Static and Dynamic Cultures in Hypoxic and Normoxic Conditions.

Mesenchymal stem cells (MSCs) hold immense therapeutic potential due to their regenerative and immunomodulatory properties. However, to utilize this potential, it is crucial to optimize their in vitro cultivation conditions. Three-dimensional (3D) culture methods using cell-laden hydrogels aim to mimic the physiological microenvironment in vitro, thus preserving MSC biological functionalities. Cellulosic hydrogels are particularly promising due to their biocompatibility, sustainability, and tunability in terms of chemical, morphological, and mechanical properties. This study investigated the impact of (1) two physical crosslinking scenarios for hydrogels derived from anionic cellulose nanofibers (to-CNF) used to encapsulate adipose-derived MSCs (adMSCs) and (2) physiological culture conditions on the in vitro proliferation, differentiation, and extracellular vesicle (EV) production of these adMSCs. The results revealed that additional Ca2+-mediated crosslinking, intended to complement the self-assembly and gelation of aqueous to-CNF in the adMSC cultivation medium, adversely affected both the mechanical properties of the hydrogel spheres and the growth of the encapsulated cells. However, cultivation under dynamic and hypoxic conditions significantly improved the proliferation and differentiation of the encapsulated adMSCs. Furthermore, it was demonstrated that the adMSCs in the CNF hydrogel spheres exhibited potential for scalable EV production with potent immunosuppressive capacities in a bioreactor system. These findings underscore the importance of physiological culture conditions and the suitability of cellulosic materials for enhancing the therapeutic potential of MSCs. Overall, this study provides valuable insights for optimizing the in vitro cultivation of MSCs for various applications, including tissue engineering, drug testing, and EV-based therapies.

Use of nanocelluloses from orange peel and ZnO as hybrid nanofiller in developing functionalized starch nanocomposite for edible coatings

AbstractThis study explores the formulations of orange peel nanocelluloses (NC) with tailored dimensions for the development of functionalized nanocomposites coatings on green chilies. In the present century, the valorization of agro‐waste, specifically orange peel for developing NC facilitated sustainable packaging such as edible films and coatings with improved properties has received importance. As, this approach aligns with the sustainable development goals, including reduced food waste and agro waste. For the work, the derived orange peel celluloses were acid hydrolyzed using sulfuric acid (H2SO4) and hydrochloric acid (HCl) to deliver cellulose nanofibers (CNF) and cellulose nanoparticles (CNP), respectively. The fabricated CNP and CNF were characterized using Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and thermogravimetric analysis (TGA). The FESEM morphology showed the formation of CNP with diameter ranges from 42.4 to 108 nm and formation of CNF with diameter ranged from 27.4 to 50.5 nm. The creation of the functionalized nanocomposite was done by reinforcing with hybrid nanofillers consisting CNF, CNP consecutively with ZnO in corn starch for tailormade packaging properties in terms of mechanical, physicochemical, optical, thermal properties, and so on. The results reveal improved tensile strength, and reduced water vapor transmission rates of nanocomposite with the addition of hybrid nanofillers. Additionally, green chilies were coated with the functionalized nanocomposites prepared by different concentrations of nanofillers. The storage analysis was performed in terms of weight loss, total chlorophyll content, and microbiological analysis. The developed coatings were found to be effective in extending the shelf life of green chilies. The control samples showed significantly higher weight loss compared to coated ones. The coated samples showed significantly better firmness and total chlorophyll content after 20 days of storage. In comparison to other coatings, NC and ZnO incorporated starch‐based coating was found to be the most effective in maintaining the quality of fresh green chilies throughout the storage. Thus, incorporating NC and ZnO in starch‐based films and coatings presents a promising avenue for sustainable packaging and preservation.Highlights Agro‐waste orange peel was valorized to develop sustainable food packaging. Orange peel‐based nanocellulose was developed using H2SO4 and HCl. Nanocomposite film was developed using hybrid nanofillers. Nanocomposites provide tailored properties due to the nanofillers. Developed nanocomposite was used as edible coatings on green chilies.

Effect of catalyst and oxidant concentrations in a TEMPO oxidation system on the production of cellulose nanofibers.

In traditional TEMPO oxidation systems, the high cost of TEMPO catalysts has been a significant barrier to the industrialization of oxidized CNF. From an economic perspective, presenting the characteristics of various CNFs produced with the oxidation systems with reduced catalyst usage could facilitate the industrial application of CNF across a wide range of fields. In this study, it was demonstrated that reducing the amount of TEMPO catalyst used (from 0.1 to 0.05 mmol g-1) in a conventional oxidation system increased the carboxylate content by approximately 6.3%. Furthermore, the activation of hydroxyl amine TEMPO, which is generated after the oxidation reaction of cellulose, was enhanced by adjusting the dosage of the inexpensive oxidant NaClO, leading to a 20% improvement in carboxylate content. This suggests that controlling the amount of NaClO as an oxidant can be a key parameter in adjusting the dosage of TEMPO to achieve the targeted degree of surface substitution. Results from the dispersion stability, UV-transmittance, and morphological properties of TEMPO-oxidized CNF using microfluidizing treatment showed that high carboxylate content plays a crucial role in producing high-purity CNF suspensions, which are small, uniform, and free from microfibers. Additionally, by varying the number of mechanical treatments applied to the oxidized cellulose, various types of CNF suspensions with different mean widths were obtained. We expect that these findings offer meaningful insights to end-users seeking a breakthrough in the performance limitations of final applications using cellulose nanomaterials.

Ionic liquid reinforced cellulose nanofiber with iron oxide electrocatalyst

Increased attention has been focused on the preparation of nanoarchitectures for applicability in energy, environmental and biological streams. However, concerns have been raised regarding environmental effects due to the harsh chemicals used in such preparations. To overcome this issue, the present study reports the use of a green solvent, 1-methyl-3-propyl-1H-imidazol-3-ium iodide or [Pmim]I, for the preparation of cellulose nanofiber-iron oxide (CNF-Fe2O3) composite. The as-prepared nanofiber composite is characterized with the aid of analytical tools such as X-ray diffraction (XRD), Fourier-transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy/energy dispersive X-ray spectroscopy (FE-SEM/EDX), and X-ray photoelectron spectroscopy (XPS). As a proof-of-concept demonstration, the resulting nanostructure is employed as an electrocatalyst and is compared with the bare CNFs, non-cellulose NFs and a standard RuO2 catalyst. The results indicate that the CNF-Fe2O3 composite achieves a standard current density (j) of 10 mA cm−2 at only 260 mV compared to 280, 290, and 370 mV for the standard RuO2, the bare CNFs, and non-cellulose nanofibers (NFs), respectively. These differences become more prominent at a high current density of 100 mA cm−2, where the CNF-Fe2O3 requires only 310 mV, while the CNFs, RuO2, and NFs consume 360, 370, and 550 mV, respectively.

Effects of nanosilica and nanocellulose on poly(butylene adipate‐co‐terephthalate) nanocomposites for food packaging applications

AbstractPolymeric materials are highlighted in the global market due to their low cost, excellent properties, and diversity of applications, such as food packaging, which in addition to protecting packaged foods also promotes control and conservation against contaminants. Thus, the objective of this research is to investigate the effects of adding silica nanoparticles and cellulose nanofibers, alone and together, on the properties of poly(butylene adipate‐co‐terephthalate), aiming for application in food packaging. For this purpose, PBAT and the nanofillers were initially mixed in a rheometer to produce masterbatches, and, then, to be processed by a single screw extruder to generate the nanocomposites. The nanocomposites are analyzed by scanning electron microscopy, x‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry, nuclear magnetic resonance, tensile testing, water contact angle, and microbial permeability. In low concentrations, it is observed that the system tends to be less heterogeneous. Nanoparticles do not interfere with thermal stability and present a barrier to microorganisms. Interestingly, in the two conditions studied, polymers with cellulose nanofibers or silica nanoparticles have filtering capacity, being effective as physical barriers to the growth of microorganisms within 60 days. However, the effect on mechanical properties is small, being more pronounced with the use of cellulose nanofibers.

Production of Cellulose Nanofibers From Pineapple Peel (Ananas comosus) and Application in Biodegradable Films

AbstractThe waste of pineapple (Ananas comosus) juice accounts for 35% of the fruit's weight, and this organic material is rich in fibers and cellulose, making it a promising source for producing new ingredients for biodegradable packaging. This study objected to cellulose‐produced nanofibers from pineapple peel by chemical and enzymatic treatment combined with mechanical treatment and subsequently evaluated the application of these nanofibers as a reinforcing agent in biodegradable films. The cellulose nanofibers produced through enzymatic treatment with a sonicator presented the best results and were applied in biodegradable films at concentrations of 3% and 6%. The addition of 6% of cellulose nanofibers increased the tension (26.01 ± 0.78). It reduced the elongation percentage (3.27 ± 0.38) of films in addition to expanding the biodegradability, with up to 96% degradation observed after just 1 day. The use of nanofibers obtained from pineapple peel is a promising ingredient for the development of biodegradable packaging.

CO2 foam structure and displacement dynamics in a Hele–Shaw cell

The substitution of CO2 gas with CO2 foam for improved mobility control has recently attracted research attentions in enhanced oil recovery (EOR) as well as aquifer and soil remediation. However, the interplay between CO2 foam properties and oil displacement remains less investigated. In this work, using clear visualizations, we systematically investigate the dynamic advection-dominated foam morphology, its corresponding viscosity, and the efficiency and dynamics of oil displacement process by CO2 foam in a Hele–Shaw cell under the effects of gas ratio (Rg), fluid injection rates (Qt), and surfactant type. Clear visualization enables particle image velocimetry to calculate actual, rather than nominal, foam velocity that significantly affects the estimated foam viscosity. Our results demonstrate that at elevated gas ratios under constant total injection rate, larger and more uniform bubbles with less number density and greater interfacial area are obtained. Increasing the injection rates leads to finer foam texture at a constant gas ratio. Different foam structures have an impact on the foam viscosity, with a general increasing trend of viscosity for larger bubbles as Rg increases from 0.5 to 0.85. The higher the foam viscosity, the more stable displacement interfaces with less viscous fingers are observed, leading to improved sweeping rates. The green surfactants (saponin + Cellulose NanoFibers) provide foams with higher viscosity and, thus, more stable displacement interfaces. These findings highlight the important effect of Rg–dependent foam structure on its viscosity, which in turn is crucial for controlling the mobility of CO2 foam to maximize oil recovery rate during EOR processes.

Bio-Templated Aerogel Fibers: Heterogeneous Spinodal Architecting and In Situ Fibrillation of Thermoplastic Polyurethane-Silica on Nanostructured Cellulose Nanofiber Scaffold for Enhanced Thermomechanical Performance.

This study addresses the inherent fragility and fractal limitations of traditional silica aerogels by developing a bio-templated aerogel fiber. Integrating cellulose nanofibers (CNFs), thermoplastic polyurethane (TPU), and silica aerogel (SA) in a dimethyl sulfoxide (DMSO) dispersion, a gel-spinning technique was employed to create aerogel fibers with superior thermomechanical performance. CNF also provided excellent rheological modification for successful spinnability, fast gelation, and fiber formation. The unique hierarchical structure of these fibers, formed through hot-stretching and surface modification, combined the superior mechanical strength and flexibility of TPU with the exceptional insulation properties of CNF and SA. The CNF network, encapsulated within the SA particles, formed a core-shell structure, axially aligned, that significantly enhances the thermal stability and mechanical performance of the fibers while maintaining a lightweight and porous architecture. Comprehensive morphological, thermal, and mechanical analyses were conducted to evaluate the properties of the developed aerogel fibers. Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy verified the successful surface modification and grafting reactions on CNF, contributing to improved hydrophobicity and thermal insulation. Adjusting the CNF content allowed for tailoring of the thermomechanical characteristics, with a notable 294% increase in tensile strength from 5.3 to 15.6 MPa and an enhanced crystallization temperature from 106 to 119.97 °C. Furthermore, cyclic tensile and compression tests validated the durability and shape recovery capabilities of the aerogel fibers, making them promising candidates for high-performance applications in extreme environments. The thermal conductivity validated by experimental data further highlights the potential of CNF-based aerogel fibers as sustainable and multifunctional materials for advanced thermal insulation, mechanical reinforcement, and flexible structural applications.

Impact of cellulose enrichment on castor oil polyurethane sheets: A path to greener materials

AbstractDue to the growing concern over the depletion of the global crude oil stock and environmental issues, the replacement of petroleum‐based polymers with environmentally benign alternatives derived from renewable resource has attracted great attention. In the current study, four different polyurethane (PU) sheets were synthesized from unmodified castor oil (CO) and hexamethylene diisocyanate (HDI), incorporating cellulose nanofibers (CNF) as a filler. The mixture consisting molar ratio of CO, HDI, and CNF in a ratio of 1:5:0.8 yielded the best results. This formulation achieved a tensile strength of 22.55 MPa and an elongation at break of 55.9%. Additionally, the resulting PU sheets exhibited excellent thermal properties, with a glass transition temperature (Tg) and melting temperature (Tm) that were notably enhanced, further highlighting the effectiveness of this specific mixture in producing high‐performance, bio‐based PUs. Fourier‐transform infrared spectroscopy (FTIR), thermal, and mechanical characterizations indicated that both reinforced and unreinforced PU exhibited properties within acceptable ranges. Given the bio‐based origins of CO and cellulose, the synthesized polymers are biodegradable and suitable for biomaterial applications. The study confirms that the bio‐based origins of CO and cellulose render synthesized polymers biodegradable, suitable for various biomaterial applications.

Inside Cover

The cover image is based on the Article Bio‐composite using polyhydroxyalkanoates and sustainable nanofillers derived from cellulose nanofibers and its application for an environmentally friendly packaging material by Jaemin Jo and Bonwook Koo, https://doi.org/10.1002/pol.20240419. image

High-Performance Dual-Redox-Mediator Supercapacitors Based on Buckypaper Electrodes and Hydrogel Polymer Electrolytes.

In recent years, the demand for solid, thin, and flexible energy storage devices has surged in modern consumer electronics, which require autonomy and long duration. In this context, hybrid supercapacitors have become strategic, and significant efforts are being made to develop cells with higher energy densities while preserving the power density of conventional supercapacitors. Motivated by these requirements, we report the development of a new high-performance dual-redox-mediator supercapacitor. In this study, cells were constructed using fully moldable buckypapers (BPs), composed of carbon nanotubes and cellulose nanofibers, as electrodes. We evaluated the compatibility of BPs with hydrogel polymer electrolytes, based on 1 mol L-1 H2SO4 and polyvinyl alcohol (PVA), supplemented with different redox species: methylene blue, indigo carmine, and hydroquinone. Solid cells were constructed containing two active redox species to maximize the specific capacity of each electrode. Considering the main results, the dual-redox-mediator supercapacitor exhibits high energy density of 32.0 Wh kg-1 (at 0.8 kW kg-1) and is capable of delivering 25.9 Wh kg-1 at high power demand (4.0 kW kg-1). Stability studies conducted over 10,000 galvanostatic cycles revealed that the PVA polymer matrix benefits the system by inhibiting the crossover of redox species within the cell.

Research on Efficient Electromagnetic Shielding Performance and Modulation Mechanism of Aero/Organo/Hydrogels with Gravity-Induced Asymmetric Gradient Structure.

To eliminate electromagnetic pollution, it is a challenging task to develop highly efficient electromagnetic shielding materials that integrate microwave absorption (MA) performance with high shielding capability and achieve tunability in shielding performance. Asymmetrically structured aero/organo/hydrogels with a progressively changing concentration gradient of liquid metal nanoparticles (LMNPs), induced by gravity, are prepared by integrating the conductive fillers Ti3C2Tx MXene and LMNPs into a dual-network structure composed of polyvinyl alcohol and cellulose nanofibers. Benefiting from the unique structure, which facilitates the absorption-reflection-reabsorption process of electromagnetic waves along with conductive fillers and the porous structure, three types of gels demonstrate efficient shielding performance. HPCML achieves a total shielding effectiveness (SET) of up to 86.9dB and a reflection shielding effectiveness (SER) of as low as 2.85dB. Especially, APCML, with an ultra-low reflection coefficient (R) of 6.4%, achieves compatibility between shielding performance and MA properties. The relationship between dispersing media (air, water, and glycerol/water) and the shielding performance of aero/organo/hydrogels is explored, thereby achieving modulation of the shielding performance of the gel system. The work has paved a clear path for integrating absorption and shielding capabilities into a composite material, thereby providing a prototype of a highly efficient shielding material with MA performance.

Improving Hydrophobicity and Water Vapor Barrier Properties in Paper Using Cellulose Nanofiber-Stabilized Cocoa Butter and PLA Emulsions

This study explores the use of cellulose nanofiber (CNF)-stabilized Pickering emulsions for paper coatings, focusing on their rheological properties and effects on hydrophilicity and water vapor transmission rate (WVTR). Two types of Pickering emulsions, oil-in-water (O/W), were stabilized with 1 wt% CNF extracted from fique by-products. The oily phases of the emulsions were composed of poly(lactic acid) (PLA) and cocoa butter (CB). The physical stability, viscosity, and viscoelasticity of the emulsions were characterized. The emulsions were applied to the surfaces of Bond and Kraft papers using the rod-coating method. The coating process involved first applying a layer of the PLA emulsion followed by a layer of the CB emulsion. The coated papers were then evaluated by FE-SEM, contact angle, adhesion work, and water vapor transmission rate (WVTR). The results indicated that the coatings effectively produced a slightly hydrophobic surface on the papers, with contact angles approaching 90°. Initially, Kraft paper exhibited a WVTR value of 29.20 ± 1.13 g/m2·h, which significantly decreased to 7.06 ± 2.80 g/m2·h after coating, representing a reduction of 75.82%. Similarly, natural Bond paper showed a WVTR value of 30.56 ± 0.34 g/m2·h, which decreased to 14.37 ± 5.91 g/m2·h after coating, indicating a reduction of 47.02%. These findings demonstrate the potential of CNF-stabilized Pickering emulsions for enhancing the performance of paper coatings in terms of hydrophobicity and moisture barrier properties. The approach of this study aligns with global sustainability goals in packaging materials combining the use of PLA and CB to develop a waterborne coating to enhance the moisture barrier properties, demonstrated by a substantial reduction in water vapor transmission rates, and an improved hydrophobicity of coated papers.

Innovative upcycling cigarette filters into high-performance cellulose nanofiber-epoxy composites

This research introduces a novel upcycling method for transforming cigarette filters—an abundant and persistent environmental waste—into high-performance epoxy composites reinforced with cellulose nanofibers. The innovation lies in extracting cellulose acetate nanofibers from used cigarette butts via a multi-step purification and electrospinning process, followed by their conversion into regenerated cellulose nanofibers through alkaline hydrolysis. This dual-fiber approach allows us to fabricate four distinct epoxy composites, each reinforced by different nanofiber types: recycled cellulose acetate nanofibers, regenerated cellulose nanofibers from recycled cigarette filters, and their commercial counterparts. Notably, this is the first time regenerated nanofibers derived from waste cigarette filters have been utilized for epoxy composite reinforcement, demonstrating a sustainable, high-value use for a major pollutant. Comprehensive characterizations, including FTIR, XRD, SEM, and contact angle measurements, confirmed the successful regeneration of cellulose nanofibers, showing improved hydrophilicity, reduced crystallinity, and uniform nanofiber morphology with diameters between 200 and 300 nm. The innovation further extends to the mechanical performance of these composites: tensile tests revealed that those reinforced with regenerated cellulose nanofibers exhibited superior tensile strength (49.5–53.8 MPa), significantly outperforming both cellulose acetate nanofiber composites (40.1–42.6 MPa) and neat epoxy resin (31.4 MPa). This marked improvement is attributed to enhanced nanofiber dispersion and interfacial adhesion within the epoxy matrix, an essential advancement over traditional composites. In addition, thermal analysis showed that all composites maintained thermal stability in the 300–400 °C range, comparable to commercial alternatives. The regenerated nanofiber-reinforced composites also displayed enhanced optical transparency due to reduced light scattering, making them ideal candidates for applications requiring both mechanical strength and optical clarity. By pioneering the use of cigarette filter waste for fabricating advanced cellulose nanofiber composites, this study presents an eco-friendly approach to addressing environmental pollution while creating sustainable materials with superior mechanical, thermal, and optical properties.

Robust Metal Oxide Adhesion Layers for Cellulose Nanofiber-Based QCM Sensors.

Here, we demonstrate the significant role of robust metal oxide adhesion layers on the cellulose nanofiber (CNF)-based quartz crystal microbalance (QCM) humidity sensor characteristics including sensitivity and stability. In this study, we deposited various metal oxide films (NiO, TiO2, ZnO, and WO3) onto QCM Au electrodes as adhesion layers before drop-casting CNF dispersion water. These metal oxide adhesion layers significantly enhanced the stability of CNF films on QCM sensors even in a high-humidity environment where a conventional adhesion layer (polyethylenimine) for CNF could not maintain stable adhesion. There was a significant difference between different metal oxide layers in the QCM data for humidity sensing. We found a negative correlation between the QCM sensitivity and the water wettability of metal oxide surfaces. Morphology analysis of the deposited CNF films revealed that the center-concentrated CNF microstructures on the metal oxide adhesion layers rigorously explained the observed negative correlation between the sensitivity and the wettability of metal oxide surfaces. This trend was further confirmed by gradually changing the hydrophobicity of the NiO adhesion surfaces. Thus, the proposed strategy using robust metal oxide adhesion layers will be a foundation for further development of various CNF-based QCM gas sensors.

Highly Bioadaptive Scaffolds with Tuned Porous Structure Templated by Xylan Nanocrystal High Internal Phase Pickering Emulsions.

Fabrication of traditional 3D cell culturing scaffolds requires synthetic polymers or additives, posing a risk of poor biocompatibility and low biodegradability. Pickering emulsions stabilized by biobased nanomaterials can be used as templates to produce scaffolds with facile tunable porous structure, excellent cytocompatibility, and biodegradability. In this study, very stable high internal phase Pickering emulsions (HIPPE) with an oil content of 80% were successfully prepared by xylan hydrate nanocrystals (XNC). The HIPPE can exist stably for more than 30 days, exhibiting a high viscosity. By adding cellulose nanofibers (CNF) and removing the oil phase, scaffolds with a tuned porous structure and enhanced cell culturing ability were successfully fabricated. In the HIPPE templated scaffolds with XNC/CNF, XNC plays a major role in stabilizing the emulsions, while CNF improves the mechanical properties of the scaffolds, both of which are vital to the successful fabrication of the scaffolds. Compared with non-HIPPE templated scaffolds, the HIPPE templated scaffold had a higher porosity and a higher median pore size. The HIPPE templated scaffold was able to maintain 80% cell activity and showed an excellent cytocompatibility. The HIPPE templated scaffolds consisting of XNC and CNF demonstrate great potential in 3D cell culturing for medical purpose.

TEMPO oxidized cellulose nanofiber-reinforced sodium alginate encapsulated poly(acrylamide) microcapsules and its releasing behaviours for enhancing oil recovery

Poly(acrylamide) (PAM) has excellent thickening ability as a conventional flooding agent. However, PAM confronts the problems of high injection pressure and high shear loss in the process of oil extraction, which have limited its application in this field. In this work, 2, 2, 6, 6-Tetramethylpiperidinooxy oxidized cellulose nanofibers (TOCNFs) enhanced sodium alginate (SA) shell was used to encapsulate PAM to form microcapsule. The composition, morphology, structure and the releasing behaviours of TOCNFs enhanced microcapsules was tested. Mechanical stirring was used to simulate the state of polymer subjected to shear during stratigraphic transport. The release performance of the microcapsules was characterized by measuring the change of viscosity with time. The ratio of the shell material with the best performance was explored, and the enhancement mechanism of the SA shell by TOCNFs was discussed. The experiments showed that the release time of PAM from the microcapsules was significantly prolonged with the addition of TOCNFs. The longest release time was observed when the ratio of SA and TOCNFs was 5: 1, with the release time of the microcapsules from the original 8 h to 16 h. The enhanced shear resistance of the microcapsules was attributed to the semi-interpenetrating network structure of SA and TOCNFs via Ca2+ cross-linking as well as hydrogen bonding. The prepared microcapsules have promising applications in enhancing oil recovery.

Extraction of cellulose nanofibers from sugarcane bagasse at different hydrolysis conditions

This study investigated the effect of alkaline treatment and various acid hydrolysis conditions on the extraction of cellulose nanofibers from sugarcane bagasse. Alkaline treatments were conducted using sodium hydroxide and sodium hypochlorite solutions. After the alkaline treatment, acid hydrolysis was performed in solutions containing 60, 64, and 68% wt. of sulfuric acid at temperatures of 30 ± 1 °C and 45 ± 1 °C. The effectiveness of the alkaline treatment in removing non-cellulosic components was assessed by infrared spectrometry and scanning electron microscopy, which demonstrated satisfactory results in eliminating non-cellulosic components. Transmission electron microscopy revealed the impact of temperature on the dimensions of the extracted cellulose nanofibers, with acid hydrolysis at 45 °C yielding smaller nanofibers compared to hydrolysis at 30 °C. X-ray diffraction analysis showed a higher percentage of crystallinity for hydrolysis at 45 °C, which can be attributed to the removal of a substantial amount of amorphous cellulose content.