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Enhancing the antimicrobial activity of high-efficiency particulate air (HEPA) filters while maintaining filtration efficiency and pressure drop is currently an urgent issue for preventing the spread of pathogenic microorganisms. Herein, inspired by vines which can enwind fences to fix as well as decorate them, a flexible antimicrobial chitin nanofiber (ChNF@CuO x ) was fabricated and loaded onto the rigid glass fiber (GF) skeleton of a HEPA filter. Through the physical interaction, ChNF@CuO x was spontaneously enwound on GF, and ChNF@CuO x itself interweaved to form a new nanonetwork between the GF skeleton. The obtained antimicrobial air filter (ChNF@CuO x /GF) with a unique nanonetwork increased the filtration efficiency of the HEPA filter. Meanwhile, it possessed excellent inactivation ability against Staphylococcus aureus , Escherichia coli , and Candida albicans due to the urchin-like in situ grown CuO x on the ChNF. In particular, the oxygen vacancies generated unexpectedly in CuO x enabled it to produce reactive oxygen species. After eight cycles of antimicrobial assays, the antimicrobial rates of bacteria were higher than 99.5%, and those of fungi were greater than 98.3%. The successful synthesis of antimicrobial fibers and the construction of multidimensional nanoscale structures through a simple postprocessing method provide a new design mentality for antimicrobial functionalization for HEPA filters.

The fabrication of commercial cellulose nanofibrils (CNFs) into arrays with long-range ordering is of great significance for their extended applications, which, however, is severely hindered by their high disorder, aggregation, and hornified features. Herein, sub-nanoscale anionic metal oxide clusters (phosphotungstic acid, H 3 PW 12 O 40 , PTA) are applied to complex with commercial CNFs (dried powder DCNF and aqueous suspension WCNF) in aqueous media, and a long-range ordered layer structure can be facilely fabricated via typical unidirectional freezing. The surface complexation of the commercial CNFs and PTA can be confirmed through the small-angle scattering studies of the complex hydrogels. The hydrogels present similar correlation lengths in small-angle X-ray and neutron scattering measurements, suggesting the homogeneous distribution of PTA along the commercial CNFs. This gives rise to the negatively charged surface feature and further leads to strong repulsion among the commercial CNFs. Due to the disparity in sizes, the influence of PTA on the density of hydrogel networks is suppressed, and the network density is mainly dependent on the mass content of CNFs. The studies provide guidance to fabricate hydrogels with catalytic and photosensitive properties and also to design and stabilize long-range ordered structured aerogels during the removal of the nonfreezing bound water absorbed by the commercial CNFs after unidirectional freezing. This facile strategy shows great potential to broaden the application of commercial CNFs in thermal insulators, super-adsorbent materials, and supercapacitors in electrical devices.

Excessive bleeding in traumatic hemorrhage is the primary concern for natural wound healing and the main reason for trauma deaths. The three-dimensional (3D) bioprinting of bioinks offers the desired structural complexity vital for hemostasis activity and targeted cell proliferation in rapid and controlled wound healing. However, it is challenging to develop suitable bioinks to fabricate specific 3D scaffolds desirable in wound healing. In this work, a 3D composite scaffold is designed using bioprinting technology and synergistic hemostasis mechanisms of cellulose nanofibrils (TCNFs), chitosan, and casein to control blood loss in traumatic hemorrhage. Bioinks that consist of casein bioconjugated TCNF (with a casein content of 104.5 ± 34.1 mg/g) using the carbodiimide cross-linker chemistry were subjected to bioprinting for customizable 3D scaffold fabrication. Further, the 3D composite scaffolds were in situ cross-linked using a green ionic complexation approach. The covalent conjugation among TCNF, casein, and chitosan was confirmed by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), and X-ray diffraction (XRD) studies. The in vitro hemostasis activity of the 3D composite scaffold was analyzed by a human thrombin-antithrombin (TAT) assay and adsorption of red blood cells (RBCs) and platelets. The 3D composite scaffold had a better swelling behavior and a faster whole blood clotting rate at each time point than the 3D TCNF scaffold and commercial cellulose-based dressings. The TAT assay demonstrated that the 3D composite scaffold could form a higher content of thrombin (663.29 pg/mL) and stable blood clot compared to a cellulosic pad (580.35 pg/mL), 3D TCNF (457.78 pg/mL), and cellulosic gauze (328.92 pg/mL), which are essential for faster blood coagulation. In addition, the 3D composite scaffold had a lower blood clotting index (23.34%) than the 3D TCNF scaffold (41.93%), suggesting higher efficiencies for RBC entrapping to induce blood clotting. The in vivo cytocompatibility was evaluated by a 3D cell culture study, and results showed that the 3D composite scaffold could promote growth and proliferation of NIH 3T3 fibroblast cells, which is vital for wound healing. Cellulase-based in vitro deconstruction of the 3D composite scaffold showed significant weight loss (80 ± 5%) compared to the lysozyme hydrolysis (22 ± 5%) after 28 days of incubation, suggesting the biodegradation potential of the composite scaffold. In conclusion, this study proposes efficient prospects to develop a 3D composite scaffold from bioprinting of TCNF-based bioinks that can accelerate blood clotting and wound healing, suggesting its potential application in reducing blood loss during traumatic hemorrhage.

Cellulose hydrolysis is an extensively studied process due to its relevance in the fields of biofuels, chemicals production, and renewable nanomaterials. However, the direct visualization of the process accompanied with detailed scaling has not been reported because of the vast morphological alterations occurring in cellulosic fibers in typical heterogeneous (solid/liquid) hydrolytic systems. Here, we overcome this distraction by exposing hardwood cellulose nanofibers (CNFs) deposited on silica substrates to pressurized HCl gas in a solid/gas system and examine the changes in individual CNFs by atomic force microscopy (AFM). The results revealed that hydrolysis proceeds via an intermediate semi-fibrous stage before objects reminiscent of cellulose nanocrystals were formed. The length of the nanocrystal-like objects correlated well with molar mass, as analyzed by gel permeation chromatography, performed on CNF aerogels hydrolyzed under identical conditions. Meanwhile, X-ray diffraction showed a slight increase in crystallinity index as the hydrolysis proceeded. The results provide a modern visual complement to >100 years of research in cellulose degradation.

The application of chitosan nanofibers in biological tissue-engineering materials has attracted wide attention. A novel and organic solvent-free method was developed for the fabrication of rootlike chitosan nanofibers (CSNFs) with diameters of 40-250 nm. This method includes three-step mechanical processing of swelling-beating-centrifugation or swelling-beating-homogenization. The obtained nanofibers showed high yields (>95%) and positive specific surface charges (up to +375 μeq/g) and could be uniformly dispersed in the aqueous phase. The unique fiber shape and the good length-to-diameter ratio of CSNFs endowed chitosan nanofiber paper (CSNFP) products with excellent mechanical properties, and the wet tensile strength of the CSNFPs was nearly five times higher than common chitosan films. In addition, the calvaria-derived preosteoblastic cells exhibited a higher adherence efficiency and proliferation on CSNFP than on chitosan films. The chitosan nanofiber scaffold products also benefited the attachment of preosteoblastic cells and allowed them to grow in three dimensions. This method has significant industrial potential for the industrialization of chitosan nanofibers, which may have broad applications in various biomaterials.

Cellulose nanofibrils, which attract extensive attention as a bio-based, sustainable, high-performance nanofibril, are believed to be predominantly hydrophilic. This study aimed to prove the presence of an amphiphilic "Janus-type fiber surface" in water with hydrophobic and hydrophilic faces in a cellulose nanofibril (ACC-CNF) that was prepared by the aqueous counter collision method. We clarified the surface characteristics of the ACC-CNF by confocal laser scanning microscopy with a carbohydrate-binding module and congo red probes for the hydrophobic planes on the cellulose fiber surfaces and calcofluor white as hydrophilic plane probes. The results indicated the presence of both characteristic planes on a single ACC-CNF surface, which verifies an amphiphilic Janus-type structure. Both hydrophobic probes adsorbed onto ACC-CNFs for the quantitative evaluation of the degree of ACC-CNF surface hydrophobicity by Langmuir's adsorption theory based on the optimal maximum adsorption amounts for various starting raw material types.

The development of intelligent and multifunctional hydrogels having photothermal properties, good mechanical properties, sustained drug release abilities with low burst release, antibacterial properties, and biocompatibility is highly desirable in the biomaterial field. Herein, mesoporous polydopamine (MPDA) nanoparticles wrapped with graphene oxide (GO) were physically cross-linked in cellulose nanofibril (CNF) hydrogel to obtain a novel MPDA@GO/CNF composite hydrogel for controllable drug release. MPDA nanoparticles exhibited a high drug loading ratio (up to 35 wt %) for tetracycline hydrochloride (TH). GO was used to encapsulate MPDA nanoparticles for extending the drug release time and reinforcing the physical strength of the obtained hydrogel. The mechanical strength of the as-fabricated MPDA@GO/CNF composite hydrogel was five times greater compared to that of the pure CNF hydrogel. Drug release experiments demonstrated that burst release behavior was significantly reduced by adding MPDA@GO. The drug release time of the MPDA@GO/CNF composite hydrogel was 3 times and 7.2 times longer than that of the polydopamine/CNF hydrogel and pure CNF hydrogel, respectively. The sustained and controlled drug release behaviors of the composite hydrogel were highly dependent on the proportion of MPDA and GO. Moreover, the rate of drug release could be accelerated by near-infrared (NIR) light irradiation and pH value change. The drug release kinetics of the as-prepared composite hydrogel was well described by the Korsmeyer-Peppas model, and the drug release mechanism of TH from the composite hydrogel was anomalous transport. Importantly, this carefully designed MPDA@GO/CNF composite hydrogel showed good biocompatibility through an in vitro cytotoxicity test. In particular, the toxicity of GO was well shielded by the CNF hydrogel. Therefore, this novel MPDA@GO/CNF composite hydrogel with an encapsulation structure for controllable drug release and toxicity shielding of GO could be used as a very promising controlled drug delivery carrier, which may have potential applications for chemical and physical therapies.

The rheological behavior of aqueous suspensions of lignocellulose nanofibrils (LCNFs) is investigated systematically by considering the coupled effect of residual lignin and LCNF morphology. The LCNF was obtained by high-energy fluidization of TEMPO-oxidized mechanical fibers, followed by size fractionation (fibril widths of ∼5, ∼9, and ∼18 nm). The nanofibril width and the corresponding fibril-fibril interactions are strongly influenced by the presence and distribution of lignin in the respective fractions, either retained on the fibril surface or as free structures present in the finest size fraction. All samples containing lignin display dilatancy, typifying gel suspensions with aggregated hydrophobic particles. Fine fractionated samples display strong gel behavior. The coarse fractionated sample, by contrast, shows a greater tendency to flocculate via entanglement and displays less gel-like characteristics; hence, it dewaters more freely.

Various wearable aerogel sensors are emerging for their light weight, fairly wide sensing range, and sensitive sensing ability. Aramid nanofibers (ANFs) as a kind of burgeoning building blocks realize multifunctional applications in diversified fields for their innate extinguished mechanical property and thermal stability. Limited by their high insulating property, in this work ANFs were designed to integrate with a 2D emerging MXene sheet with a distinct conductive property. Herein, we report an MXene/ANFs composite aerogel through a feasible controllable vacuum filtration followed by a freeze-drying process. Benefiting from the inerratic 3D hierarchical and "mortar-brick" porous structure with an ultralow density of 25 mg/cm 3 , MXene/ANFs aerogels are proved to possess high compressible resilience and appealing sensing performance up to 1000 times. Importantly, verified by a series of simulation experiments, the MXene/ANFs aerogel sensor shows a wide detection range (2.0-80.0% compression strain), sensitive sensing property (128 kPa -1 ), and ultralow detection limit (100 Pa), which still play a flexible role in detecting human light movement and even vigorous sports after undergoing ultrahigh devastating pressures (∼623 kPa). In addition, the MXene/ANFs aerogel sensor can withstand a harsh high temperature of 200 °C and shows excellent flame resistance. The MXene/ANFs aerogel with excellent integrated property, especially the highly sensitive sensing property and excellent thermal stability, presents great potential for a human behavior monitoring sensor and sensing under certain extreme conditions.

Ionic conductors are normally prepared from water-based materials in the solid form and feature a combination of intrinsic transparency and stretchability. The sensitivity toward humidity inevitably leads to dehydration or deliquescence issues, which will limit the long-term use of ionic conductors. Here, a novel ionic conductor based on natural bacterial cellulose (BC) and polymerizable deep eutectic solvents (PDESs) is developed for addressing the abovementioned drawbacks. The superstrong three-dimensional nanofiber network and strong interfacial interaction endow the BC-PDES ionic conductor with significantly enhanced mechanical properties (tensile strength of 8 × 10 5 Pa and compressive strength of 6.68 × 10 6 Pa). Furthermore, compared to deliquescent PDESs, BC-PDES composites showed obvious mechanical stability, which maintain good mechanical properties even when exposed to high humidity for 120 days. These materials were demonstrated to possess multiple sensitivity to external stimulus, such as strain, pressure, bend, and temperature. Thus, they can easily serve as supersensitive sensors to recognize physical activity of humans such as limb movements, throat vibrations, and handwriting. Moreover, the BC-PDES ionic conductors can be used in flexible, patterned electroluminescent devices. This work provides an efficient strategy for making cellulose-based sustainable and functional ionic conductors which have broad application in artificial flexible electronics and other products.

To improve the salt tolerance/sensitivity of cellulose nanofibrils (CNFs), zwitterionic cellulose nanofibrils (ZCNFs) were prepared from softwood bleached kraft pulp fibers via a sequential process of anionic modification with 2,2,6,6-tetramethylepiperidin-1-oxyl (TEMPO)-mediated oxidation, cationic modification with (2,3-epoxypropyl) trimethylammonium chloride (EPTMAC), and high-pressure homogenization. To produce ZCNFs with different contents of cation group, EPTMAC loadings of 0.15 to 1.15 g/g fiber were explored during cationization. The obtained ZCNFs were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectra (XPS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and rheological measurements. The salt tolerance of the ZCNFs was investigated by adding mixed salts into the ZCNF dispersions. The results demonstrated that the ZCNFs with both anionic and cationic charges were produced. Compared with the TEMPO-mediated oxidized cellulose nanofibrils (TOCNFs), the ZCNFs exhibited an excellent "salt-thickening" behavior under the studied salt concentrations (2-24% w/w). Moreover, increasing the content of the cation group increased the salt tolerance/sensitivity of ZCNFs. This work demonstrated that introducing cationic charges to the anionic charged TOCNFs imparts the produced ZCNFs with excellent salt sensitivity and tolerance, which could expand the application of nanocellulose in oil recovery or wastewater treatment.

Biodegradable and renewable materials, such as cellulose nanomaterials, have been studied as a replacement material for traditional plastics in the biomedical field. Furthermore, in chronic wound care, modern wound dressings, hydrogels, and active synthetic extracellular matrices promoting tissue regeneration are developed to guide cell growth and differentiation. Cells are guided not only by chemical cues but also through their interaction with the surrounding substrate and its physicochemical properties. Hence, the current work investigated plant-based cellulose nanomaterials and their surface characteristic effects on human dermal fibroblast (HDF) behavior. Four thin cellulose nanomaterial-based coatings produced from microfibrillar cellulose (MFC), cellulose nanocrystals (CNC), and two TEMPO-oxidized cellulose nanofibers (CNF) with different total surface charge were characterized, and HDF viability and adhesion were evaluated. The highest viability and most stable adhesion were on the anionic CNF coating with a surface charge of 1.14 mmol/g. On MFC and CNC coated surfaces, HDFs sedimented but were unable to anchor to the substrate, leading to low viability.

Owing to their superior mechanical strength and structure similarity to the extracellular matrix, nanocelluloses as a class of emerging biomaterials have attracted great attention in three-dimensional (3D) bioprinting to fabricate various tissue mimics. Yet, when printing complex geometries, the desired ink performance in terms of shape fidelity and object resolution demands a wide catalogue of tunability on the material property. This paper describes surface engineered biomimetic inks based on cellulose nanofibrils (CNFs) and cross-linkable hemicellulose derivatives for UV-aided extrusion printing, being inspired by the biomimetic aspect of intrinsic affinity of heteropolysaccharides to cellulose in providing the ultrastrong but flexible plant cell wall structure. A facile aqueous-based approach was established for the synthesis of a series of UV cross-linkable galactoglucomannan methacrylates (GGMMAs) with tunable substitution degrees. The rapid gelation window of the formulated inks facilitates the utilization of these wood-based biopolymers as the feeding ink for extrusion-based 3D printing. Most importantly, a wide and tunable spectrum ranging from 2.5 to 22.5 kPa of different hydrogels with different mechanical properties could be achieved by varying the substitution degree in GGMMA and the compositional ratio between GGMMA and CNFs. Used as the seeding matrices in the cultures of human dermal fibroblasts and pancreatic tumor cells, the scaffolds printed with the CNF/GGMMA inks showed great cytocompatibility as well as supported the matrix adhesion and proliferative behaviors of the studied cell lines. As a new family of 3D printing feedstock materials, the CNF/GGMMA ink will broaden the map of bioinks, which potentially meets the requirements for a variety of in vitro cell-matrix and cell-cell interaction studies in the context of tissue engineering, cancer cell research, and high-throughput drug screening.

Cellulose nanofibrils (CNFs) in the form of hydrogels stand out as a platform biomaterial in bioink formulation for 3D printing because of their low cytotoxicity and structural similarity to extracellular matrices. In the present study, 3D scaffolds were successfully printed with low-concentration inks formulated by 1 w/v % 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized CNF with less than 1 w/v % gelatin methacrylate (GelMA). Quartz crystal microbalance with dissipation monitoring (QCM-D) measurements showed strong interaction between the two biopolymers. The UV cross-linking ability of GelMA (≤1 w/v %) was enhanced in the presence of TEMPO-oxidized CNFs. Multiple factors including strong physical interaction between CNF and GelMA, in situ cross-linking of CNF by Ca 2+ , and UV cross-linking of GelMA enabled successful 3D printing of low-concentration inks of CNF/GelMA into scaffolds possessing good structural stability. The mechanical strength of the scaffolds was tuned in the range of 2.5 to 5 kPa. The cell culture with 3T3 fibroblasts revealed noncytotoxic and biocompatible features for the formulated inks and printed scaffolds. More importantly, the incorporated GelMA in the CNF hydrogel promoted the proliferation of fibroblasts. The developed low-concentration CNF/GelMA formulations with a facile yet effective approach to fabricate scaffolds showed great potential in 3D printing for wound healing application.

The three-dimensional (3D) printed scaffolds were prepared by partial cross-linking of TEMPO-oxidized cellulose nanofibril/alginate hydrogel using calcium ions for printing the hydrogel while maintaining its shape, fidelity, and preventing the collapse of the filaments. The prepared scaffolds were fully cross-linked using calcium ions immediately after printing to provide the rigidity of the hydrogel and give it long-term stability. The composition of the prepared pastes was adjusted in view of the description of the hydrogel and 3D printing parameters. The rheological properties in terms of thixotropic behavior and viscosity recovery of hydrogels were investigated by performing steady shear rate experiments. The results show that the viscosity recovery for pure alginate hydrogel was only about 16% of the initial value, whereas it was 66% when adding cellulose nanofibrils to alginate. Consequently, the shape of the pure alginate scaffold was soft and easy to collapse contrarily to the composite scaffold. The biomimetic mineralization process of printed scaffolds using simulated body fluid, mimicking the inorganic composition of human blood plasma, was performed and the hydroxyapatite nucleation on the hydrogel was confirmed. The strength properties of the fabricated scaffolds in terms of compressive strength analysis were also investigated and discussed. The results show that the alginate/TEMPO-oxidized cellulose nanofibril system may be a promising 3D printing scaffold for bone tissue engineering.

Natural hydrogels have attracted extensive research interest and shown great potential for many biomedical applications. In this study, a series of biocompatible hydrogels was reported based on the self-assembly of positively charged partially deacetylated α-chitin nanofibers (α-DECHN) and negatively charged 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNF) for anticancer drug delivery. The formation mechanisms of the α-DECHN/TOCNF hydrogels with different mixing proportions were studied, and their morphological, mechanical, and swelling properties were comprehensively investigated. Additionally, the drug delivery performance of the hydrogels was compared via sustained release test of an anticancer drug (5-fluorouracil). The results showed that the hydrogel with higher physical cross-linking degree exhibited a higher drug loading efficiency and drug release percentage.

The state of dispersion and the interactions between a polymer and a filler in a nanocomposite crucially define its properties and performance. The affinity of polylactide (PLA) with vegetable and animal proteins (casein, gelatin, soy protein isolate, and hydrolysate) is investigated and their role as eco-friendly dispersants and compatibilizers of cellulose nanofibrils (CNF) is elucidated. The affinity of the proteins with PLA is determined by using sensograms acquired by electroacoustic (quartz crystal microgravimetry) and optical (surface plasmon resonance) techniques. The surface energy of PLA increases upon protein adsorption while the opposite effect is observed for CNF, under identical experimental conditions. A significant improvement in the thermodynamic work of adhesion for PLA/CNF systems is predicted by application of the denatured proteins at low concentrations (∼20% and ∼15% enhancement with soy protein and casein at pH 3 and pH 8, respectively). We offer a robust method to screen denatured proteins and to tailor the wettability and material compatibility in the synthesis of bionanocomposites based on CNF and PLA.

Cellulose nanofibrils (CNFs) are produced and commonly used in the form of aqueous suspensions or gels. A number of studies have focused lately on rheological properties of CNF suspensions, which gives insight into properties of such materials and can reflect their behavior during handling. This Review summarizes the recent progress in rheological studies on CNF aqueous suspensions using rotational rheometry. Here, we discuss linear viscoelastic properties, i.e., frequency-dependent storage and loss moduli; shear flow behavior, i.e., apparent viscosity and shear stress as a function of shear rate; local flow characteristics, etc. In this Review, we point out that the rheological behavior of at least two types of CNF suspensions should be distinguished: (i) ones produced using mechanical fibrillation with or without enzymatic pretreatment (no surface chemical modification), which possess highly flocculated structure, and (ii) ones produced involving chemical modification pretreatments, e.g., carboxylation, carboxymethylation, quaternization, or sulfonation, which possess better colloidal stability and do not evidently flocculate.

In this work, we take advantage of the rod-like structure of electrosterically stabilized nanocrystalline cellulose (ENCC, with a width of about 7 nm and a length of about 130 nm), which has dicarboxylated cellulose (DCC) chains protruding from both ends, providing electrosterical stability for ENCC particles, to chemically end-to-end assemble these particles into nanocellulose fibers. ENCC with shorter DCC chains can be obtained by a mild hydrolysis of ENCC with HCl, and subsequently the hydrolyzed ENCC (HENCC, with a width of about 6 nm and a length of about 120 nm) is suitable to be assembled into high aspect ratio nanofibers by chemically cross-linking HENCC from one end to another. Two sets of HENCC were prepared by carbodiimide-mediated formation of an alkyne and an azide derivative, respectively. Cross-linking these two sets of HENCC was performed by a click reaction. HENCCs were also end-to-end cross-linked by a bioconjugation reaction, with a diamine. From atomic force microscopy (AFM) images, about ten HENCC nanoparticles were cross-linked and formed high aspect ratio nanofibers with a width of about 6 nm and a length of more than 1 μm.

All-cellulose nanocomposite was directly fabricated using nanowelding of cellulose microfibers as a starting material, in 1-butyl-3-methylimidazolium chloride (BMIMCl) as a solvent, for the first time. The average diameter of the reinforcing component (undissolved nanofibrils) in the nanocomposite made directly from cellulose microfibers (NC-microfiber) was 53 ± 16 nm. Owing to its high mechanical properties (tensile strength of 208 MPa and Young's modulus of 20 GPa), high transparency (76% at a wavelength of 800 nm), and complete barrier to air and biodegradability, the NC-microfiber is regarded as a high multiperformance material. The NC-microfiber made directly from cellulose microfibers showed similar macro-, micro-, and nanostructures and the same properties as those made from solvent-based welding of ground cellulose nanofibers (NC-nanofiber). Omitting the step of cellulose nanofiber production makes the direct production of all-cellulose nanocomposite from cellulose microfibers easier, shorter, and cheaper than using cellulose nanofibers as starting material. The direct nanowelding of macro/micrometer-sized materials is theorized to be a fundamental approach for making nanocomposites.

Interest in xylan-rich hemicelluloses (XH) film is growing, and efforts have been made to prepare XH films with improved mechanical properties. This work described an effective approach to produce nanocomposite films with enhanced mechanical properties by incorporation of cellulose nanofibers (CNFs) into XH. Aqueous dispersions of XH (64-75 wt %), sorbitol (16-25 wt %), and CNF (0-20 wt %) were cast at a temperature of 23 °C and 50% relative humidity. The surface morphology of the films was revealed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The thermal properties and crystal structure of the films were evaluated by thermal analysis (TG) and X-ray diffraction (XRD). The surface of XH films with and without CNF was composed primarily of nanonodules, and CNFs were embedded in the XH matrix. Freeze-dried XH powder was amorphous, whereas the films with and without CNF showed a distinct peak at around 2θ = 18°, which suggested that XH molecules aggregated or reordered in the casting solution or during water evaporation. Furthermore, the nanocomposite films had improved thermal stability. XH film with 25 wt % plasticizer (sorbitol, based on dry XH weight) showed poor mechanical properties, whereas incorporation of CNF (5-20 wt %, based on the total dry mixture) into the film resulted in enhanced mechanical properties due to the high aspect ratio and mechanical strength of CNF and strong interactions between CNF and XH matrix. This effective method makes it possible to produce hemicellulose-based biomaterials of high quality.