Bacterial Cellulose Nanofibers as Reinforcement for Preparation of Bamboo Pulp Based Composite Paper

Bamboo fibers(BFs),with features of renewability and biodegradability,have been widely used in paper-making products.In order to improve the mechanical properties and water absorption behaviors of the BF paper,bacterial cellulose nanofibers(BCNFs)as environmentally friendly nano-fibrillated cellulose(NFC)were combined with BFs.The structures and properties of the BF/BCNF composite paper were characterized by field emission scanning electron microscopy(FE-SEM),X-ray diffraction(XRD),Fourier transforms infrared(FTIR)spectroscopy,mechanical tests,pore size tests,and water absorption tests.The results indicated that the addition of BCNFs could significantly improve the water absorption capacity and mechanical properties.The water absorption ratio of the BF/BCNF composite paper with a BCNF mass fraction of 9%comes to 443%,about 1.33 times that of the pure BF paper.At the same BCNF content,the tensile strength of the BF/BCNF composite paper in dry and wet states was 12.37 MPa and 200.9 kPa,respectively,increasing by 98.24%and 136.91%as compared with that of the BF paper.

Atmosphere-free activation methodology for holey graphene/cellulose nanofiber-based film electrode with highly efficient capacitance performance

An efficient chamber-induced activation method was applied for the preparation of holey graphene/cellulose nanofiber-based film with high specific surface area(SSA)and multiple channels through the graphene nanosheets.With the cellulose nanofiber(CNF)simultaneously serving as“dispersing agent,”“spacer,”and“activating agent,”the graphene oxide(GO)nanosheets are perforated by the pyrolysis gas from CNF in the confined space inside the hybrid films,uniformly dispersed,and sandwiched between CNF networks with less agglomeration and restacking.Additionally,we have proved that H2O and H2 are primarily responsible for the activation and etching of GO/CNF film.As the CNF content increases,the mesoporosity of the activated reduced GO/CNF(A-RGO/CNF)film increases,and the graphene nanosheets show more nanopore perforations.Benefitting from the high SSA,high density,moderate mesoporosity,and abundant channels for ion diffusion through the graphene nanosheets,the A-RGO/CNF film exhibits the highest specific capacitance of 323(236)F g^(−1)(F cm^(−3))at 1Ag^(−1).For the A-RGO5/CNF5 film containing half CNF and half GO,an excellent comprehensive electrochemical performance including superior rate performance(208(160)F g^(−1)(F cm^(−3))at 60Ag^(−1))is exhibited.Moreover,the A-RGO5/CNF5 electrode in an all-solid-state flexible symmetric supercapacitor delivers a high specific capacitance of 250(193)F g^(−1)(F cm^(−3))at 1Ag^(−1).This study provides a novel idea for the preparation of holey graphene-based film for supercapacitor electrodes.The strategy of simultaneously employing CNF as“dispersing agent,”“spacer,”and“activating agent”also offers a new vision for the assembly of homogeneous nanohybrid material and the utilization of pyrolysis gas.

Cellulose nanofiber-derived carbon aerogel for advanced room-temperature sodium–sulfur batteries

Room-temperature sodium–sulfur(RT/Na–S)batteries are regarded as promising large-scale stationary energy storage systems owing to their high energy density and low cost as well as the earth-abundant reserves of sodium and sulfur.However,the diffusion of polysulfides and sluggish kinetics of conversion reactions are still major challenges for their application.Herein,we developed a powerful and functional separator to inhibit the shuttle effect by coating a lightweight three-dimensional cellulose nanofiber-derived carbon aerogel on a glass fiber separator(denoted NSCA@GF).The hierarchical porous structures,favorable electronic conductivity,and three-dimensional interconnected network of N,S-codoped carbon aerogel endow a multifunctional separator with strong polysulfide anchoring capability and fast reaction kinetics of polysulfide conversion,which can act as the barrier layer and an expanded current collector to increase sulfur utilization.Moreover,the hetero-doped N/S sites are believed to strengthen polysulfide anchoring capability via chemisorption and accelerate the redox kinetics of polysulfide conversion,which is confirmed from experimental and theoretical results.As a result,the assembled Na–S coin cells with the NSCA@GF separator showed a high reversible capacity(788.8 mAh g^(−1) at 0.1 C after 100 cycles)and superior cycling stability(only 0.059%capacity decay per cycle over 1000 cycles at 1 C),thereby demonstrating the significant potential for application in high-performance RT/Na–S batteries.

Electrostatic Self-Assembly of Ti_(3)C_(2)T_(x) MXene/Cellulose Nanofiber Composite Films for Wearable Supercapacitor and Joule Heater

The titanium carbide nanosheets(MXene)hold great potential for fabricating high-performance electronics due to their two-dimensional layered structure,high electrical conductivity,and versatile surface chemistry.However,assembling the small MXene nanosheets into flexible macroscopic films for wearable electronics still remains a challenge.Herein,we report the hierarchical assembling of MXene nanosheets and cellulose nanofibers into high-performance composite films via an electrostatic self-assembly strategy induced by polyethyleneimine.Benefited from the nacre-like microstructure of MXene"bricks"and cellulose nanofibers"mortars"interlocked by polyethyleneimine via hydrogen bonding and electrostatic interaction,composite films possess integrated superior flexibility,high tensile strength,and stable electrical conductivity,which are advantageous for wearable electronic applications.To provide a proof-of-concept design,a symmetric quasi-solid-state supercapacitor with the as-prepared composite film as electrode is fabricated,which exhibits a specific capacitance of 93.9 mF cm^(-2)at a current density of 0.1 mA cm^(-2)and almost constant capacitive behavior under different bending states.In addition,the composite film possesses capacities of electrothermal conversion and complete degradation in a hydrogen peroxide solution.These results demonstrate that the electrostatically self-assembled composite films hold great promise in the development of highly flexible,mechanically robust,and environmentally friendly energy storage and conversion devices.

CoN_(x)C active sites-rich three-dimensional porous carbon nanofibers network derived from bacterial cellulose and bimetal-ZIFs as efficient multifunctional electrocatalyst for rechargeable Zn–air batteries

In this work, a CoNxC active sites-rich three-dimensional porous carbon nanofibers network derived from bacterial cellulose and bimetal-ZIFs is prepared via a nucleation growth strategy and a pyrolysis process.The material displays excellent electrocatalytic activity for the oxygen reduction reaction, reaching a high limiting diffusion current density of -7.8 mA cm^(-2), outperforming metal–organic frameworks derived multifunctional electrocatalysts, and oxygen evolution reaction and hydrogen evolution reaction with low overpotentials of 380 and 107 mV, respectively. When the electrochemical properties are further evaluated, the electrocatalyst as an air cathode for Zn-air batteries exhibits a high cycling stability for63 h as well as a maximum power density of 308 mW cm^(-2), which is better than those for most Zn-air batteries reported to date. In addition, a power density of 152 mW cm^(-2) is provided by the solid-state Zn-air batteries, and the cycling stability is outstanding for 24 h. The remarkable electrocatalytic properties are attributed to the synergistic effect of the 3 D porous carbon nanofibers network and abundant inserted CoNxC active sites, which enable the fast transmission of ions and mass and simultaneously provide a large contact area for the electrode/electrolyte.

In Situ Synthesis of Cuprous Oxide/Cellulose Nanofibers Gel and Antibacterial Properties

Cellulose nanofibers were synthesized by acetobacter xylinum(xylinum 1.1812).The cellulose nanofibers with 30-90 nm width constructed three-dimension network gel,which could be used as a wound dressing since it can provide moist environment to a wound.However,cellulose nanofibers have no antimicrobial activity to prevent wound infection.To achieve antimicrobial activity,the cellulose nanofibers can load cuprous oxide(Cu2O)particles on the surface.The cuprous oxide is a kind of safe antibacterial material.The copper ions can be reduced into cuprous oxides by reducing agents such as glucose,N2H4 and sodium hypophosphite.The cellulose nanofibers network gel was soaked in CuSO4 solution and filled with copper ions.The cuprous oxide nanoparticles were in situ synthesized by glucose and embedded in cellulose nanofibers network.The morphologies and structure of the composite gel were analyzed by FESEM,FTIR,WAXRD and inductively coupled plasma(ICP).The sizes of Cu2O embedded in cellulose nanofibers network are 200-500 nm wide.The peak at 605 cm−1 attributed to Cu(I)-O vibration of Cu2O shits to 611 cm−1 in the Cu2O/cellulose composite.The Cu2O/cellulose nanofibers composite reveals the obvious characteristic XRD pattern of Cu2O and the results of ICP show that the content of Cu2O in the composite is 13.1%.The antibacterial tests prove that the Cu2O/cellulose nanofibers composite has the high antibacterial activities which is higher against S.aureus than against E.coli.

Effect of High Pressure Homogenization Treatment on Structure and Properties of Soybean Residue Cellulose Nanofibers

To reduce the adverse effects of non-cellulose materials on subsequent homogenization,the effects of a high-pressure homogenization treatment on the structure and properties of cellulose nanofibers(CNF)prepared by acid treatment of soybean residue were studied.The effects of the number of homogenization step on the microfibrillation degree,crystalline structure and mechanical properties of the soybean residue were analyzed by SEM,FT-IR,XRD,TG and DTG.The results showed that an increase in the number of homogenization steps led to an increase in the degree of microfibrillation,a more uniform distribution of the CNF diameter,and an increase in the crystallinity of CNF.However,but when the number of homogenization steps exceeded 15,the rate of change decreased,and the crystallinity of CNF decreased.As the number of homogenization steps increased,the average degree of polymerization and average molecular weight of CNF decreased continuously,and after 15 homogenization steps,their rate of change also decreased.Therefore,15 steps of high-pressure homogenization represented a suitable number of steps to prepare the soybean residue CNF with an average diameter of 15 nm.

Application of Cellulose and Cellulose Nanofibers in Oil Exploration

In this article, the application of cellulose and cellulose nanofibers in oil exploration was discussed, and the research status of using cellulose and cellulose nanofibers as oil displacement agents, oil-well cementing additives, and foam stabilizers were summarized.

Ketoprofen/ethyl Cellulose Nanofibers Fabricated Using an Epoxy-coated Spinneret

The present study investigates the preparation of sustained release drug-loaded nanofibers using a novel epoxy-coated spinneret. With ethyl cellulose (EC) and ketoprofen (KET) as the filament-forming matrix and the active pharmaceutical ingredient, Drug-loaded composite nanofibers are generated smoothly and continuously with few user interventions. Field-emission scanning electron microscopic observations demonstrated that the composite nanofibers prepared using the epoxy-coated spinneret have better quality than those from a traditional stainless steel spinneret in terms of diameter and its distribution. Both of the composite nanofibers are in essential a molecular solid dispersion of EC and KET based on the hydrogen bonding between them, as verified by XRD and ATR-FTIR results. In vitro dissolution tests show that the nanofibers resulted from the new spinneret provide a finer sustained KET release profile than their counter-parts. Epoxy-coated spinneret is a useful tool to facilitate the electrospinning process through the prevention of clogging for generating high quality nanofibers.

Isolation and Characterization of Cellulose Nanofibers from Argentine Tacuara Cane(Guadua Angustifolia Kunth)

New trends in the area of material improvement are the use of natural nano-charges from renewable biomass,improving the value and sustainability of our country’s natural products.Bamboo is widely used in many countries of the world,although in Argentina,despite being commercialized and exported for the manufacture of wood floors,it goes unnoticed despite having native species.Therefore,researchers identified the native and exotic species present in our country and are working on novel uses.In this context,it is proposed the Argentine Tacuara Cane(Guadua Angustifolia Kunth),endemic plant as a new source of nanocellulosic materials,where stem fibers have been isolated using a green method achieving with yield of 45.9%of cellulose.The cellulose nanofibrils(CNF)were obtained using a green homogenization method.The CNF exhibited web-like long fibrous structure with the diameter of 10-20 nm.The crystallinity was 65.5%,as for the onset temperature of thermal decomposition was 212°C.The nanocellulose isolated from the Tacuara Cane seed fibers has a high potential to be used as a new source of cellulose-based nanofiller for the reinforcement of bionanocomposite films.

The Influence of Sheath Solvent’s Flow Rate on the Quality of Electrospun Ethyl Cellulose Nanofibers

The present research investigates the influence of sheath solvent’s flow rate on the quality of electrospun ethyl cellulose (EC) nanofibers using a modified coaxial process. With 24 w/v % EC in ethanol as electrospinnable core fluid and ethanol as sheath fluid, EC nanofibers generated under different sheath flow rates were generated from the modified processes. FESEM observations demonstrate that the modified process is effective in preventing the clogging of spinneret for a smooth electrospinning. The key for the modified coaxial process is the reasonable selection of a sheath flow rate matching the drawing process of core EC fluid during the electrpospinning. The EC nanofibers’ diameters (D, nm) could be manipulated through the sheath-to-core flow rate ratio (f) as D = 819-1651f (R= 0.9754) within a suitable range of 0 to 0.25. The present paper provides useful data for the implementation of the modified coaxial process controllably to obtain polymer nanofibers with high quality.

Molecular Dynamics Study on Transmission Mechanism of Torsional Deformation in Cellulose Nanofibers with Hierarchical Structure

Cellulose nanofiber (CNF) is a fibrous and nano-sized substance produced by decomposition of bulk-type cellulose which is a main component of plants. It has high strength comparable to steel, and it shows low environmental load during a cycle of production and disposal. Besides it has many excellent properties and functions such as high rigidity, light-weight, flexibility and shape memory effect, so it is expected as a next-generation new material. Usually it is composed of many cellulose micro fibrils (CMFs) in which molecular chains of cellulose are aggregated in a crystal structure, the knowledge of mechanical properties for each CMF unit is important. Since actual fibrils are complicatedly intertwined, it is also crucial to elucidate the transmission mechanism of force and deformation not only in one fibril but also in between fibrils. How the dynamic and hierarchical structure composed of CMFs responds to bending or torsion is an interesting issue. However, little is known on torsional characteristics (shear modulus, torsional rigidity, etc.) concerning CMF. In general, in a wire-like structure, it is difficult to enhance torsional rigidity and strength, compared with tensile ones. Therefore, in this study, we try to build a hierarchical model of CNF by multiplying CMF fibers and to conduct molecular dynamics simulation for torsional deformation, by using hybrid model between all-atom and united-atoms model. First, shear modulus was estimated for one CMF fibril and it showed a value close to the experimental values. Also, we assume a state in which two CMFs are ideally arranged in parallel, and create a hierarchical structure. We evaluate the dependence on the temperature for the bond strength and toughness in the hierarchical structures. Furthermore, we mentioned the transmission mechanism between components of a hierarchical structure.

Emulsion Graft Polymerization of Methyl Methacrylate onto Cellulose Nanofibers

Methyl methacrylate (MMA) was successfully grafted onto cellulose nanofibers (CNFs) at room temperature in an emulsion system using a diethyl(1,10-phenanthroline N1,N10)zinc(II) complex (Phen-DEZ) with oxygen as the radical initiator. The effects of reaction temperature, initiator concentration, and monomer content on the grafting reaction were investigated. The molecular weight of the non-grafted PMMA, which was produced during graft polymerization, was more than 1 million, as determined by size exclusion chromatography. The PMMA-grafted CNFs were analyzed by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy, which confirmed the grafting of PMMA on the nanofiber surface. The study presents a strategy for the grafting of high-molecular weight PMMA onto CNFs in an emulsion system using Phen-DEZ and O2.

ZIF-67@Cellulose nanofiber hybrid membrane with controlled porosity for use as Li-ion battery separator

Zeolitic imidazolate framework-67(ZIF-67) was synthesized on the surface of cellulose nanofibers(CNFs)in methonal to address the problems of unhomogeneous pore size and pore distribution of pure CNF membrane.A combination of Energy Dispersive X-Ray Spectroscopy(EDS),X-ray photoelectron spectroscopy(XPS) and X-ray powder diffraction(XRD) patterns were used to determine the successful synthesis of ZIF-67@CNFs.The size of the ZIF-67 particles and pore size of the ZIF-67@CNF membrane were50-200 nm and 150-350 nm, respectively.The prepared ZIF-67@CNF membrane exhibited excellent thermal stability,lower thermal shrinkage and high surface wettability.The discharge capacity retention of the Li-ion batteries(LIBs) made with ZIF-67@CNF,glass fiber(GF),CNF and commercial polymer membranes after 100 th cycle at 0.5 C rate were 88.41%,86.22%,83.27%,and 81.03%,respectively.LIBs with ZIF-67@CNF membrane exhibited a better rate capability than these with other membranes.No damage of porous structure or peel-off of ZIF-67 was observed in the SEM images of ZIF-67@CNF membrane after100 th cycle.The improved cycling performance,rate capability,and good electrochemical stability implied that ZIF-67@CNFs membrane can be considered as a good alternative LIB separator.

Nanofibrillation of Bacterial Cellulose Using High-Pressure Homogenization and Its Films Characteristics

The microstructure of bacterial cellulose nanofibers(BCNs)film affects its characteristic.One of several means to engineer the microstructure is by changing the BCNs size and fiber distribution through a high-pressure homogenizer(HPH)process.This research aimed to find out the effects of repetition cycles on HPH process towards BCNs film characteristics.To prepare BCNs films,a pellicle from the fermentation of pineapple peels waste with Acetobacter xylinum(A.xylinum)was extracted,followed by crushing the pellicle with a high-speed blender,thereafter,homogenized using HPH at 150 bar pressure with variations of 5,10,15,and 20 cycles.The BCNs films were then formed through the casting process and drying in the oven at 60°C for 8 h followed by structural,morphological,and optical properties investigation using X-ray diffraction(XRD),scanning electron microscopy(SEM)and Fourier transform infrared(FTIR)spectrometer along with BCNs films porosity,tensile and roughness test.The research showed that the effect of HPH cycle on BCNs resulted in the highest film tensile strength by 109.15 MPa with the lowest surface roughness(Ra)of 0.93±0.10μm at 10 cycles.The HPH process is effective in controlling BCNs film porosity level.The HPH cycles influence the crystalline index and crystallite size,slightly.

Tensile Properties of Mechanically-Defibrated Cellulose Nanofiber-Reinforced Polylactic Acid Matrix Composites Fabricated by Fused Deposition Modeling

Biodegradable polymers are highly attractive as potential alternatives to petroleum-based polymers in an attempt to achieve carbon neutrality whilst maintaining the mechanical properties of the structures.Among these polymers,polylactic acid(PLA)is particularly promising due to its good mechanical properties,biocompatibility and thermoplasticity.In this work,we aim to enhance the mechanical properties of PLA using mechanically-defibrated cellulose nanofibers(CNFs)that exhibit remarkable mechanical properties and biodegradability.We also employ fused deposition modeling(FDM),one of the three-dimensional printing methods for thermoplastic polymers,for the low-cost fabrication of the products.Mechanically-defibrated CNF-reinforced PLA matrix composites are fabricated by FDM.Their tensile properties are investigated in two printing directions(0°/90°and+45°/-45°).The discussion about the relationship between printing direction and tensile behavoir of mechanically-defibrated CNF-reinforced PLA matrix composite is the unique point of this study.We further discuss the microstructure and fracture surface of mechanically-defibrated CNF-reinforced PLA matrix composite by scanning electron microscope.

Antibacterial Properties of Novel Bacterial Cellulose Nanofiber Containing Silver Nanoparticles

In this work,we describe a novel facile method to prepare long one-dimensional hybrid nanofibers by using hydrated bacterial cellulose nanofibers(BCF)as a template.Silver(Ag)nanoparticles with an average diameter of 1.5 nm were well dispersed on BCF via a simple in situ chemical-reduction between AgNO3and NaBH4at a relatively low temperature.A growth mechanism is proposed that Ag nanoparticles are uniformly anchored onto BCF by coordination with BC-containing hydroxyl groups.The bare BCF and as-prepared Ag/BCF hybrid nanofibers were characterized by several techniques including transmission electron microscopy,X-ray diffraction,thermogravimetric analyses,and ultraviolet-visible(UV-Vis)absorption spectra.The antibacterial properties of Ag/BCF hybrid nanofibers against Escherichia coli(E.coli,Gram-negative)and Staphylococcu saureus(S.saureus,Gram-positive)bacteria were evaluated by using modified Kirby Bauer method and colony forming count method.The results show that Ag nanoparticles are well dispersed on BCF surface via in situ chemical-reduction.The Ag/BCF hybrid nanofiber presents strong antibacterial property and thus offers its candidature for use as functional antimicrobial agents.

Structural Properties and Potential Applications of Cellulose Nanofiber from Bamboo Shoot Shell

Bamboo shoot shell（BSS）,a by-product from bamboo shoot processing industries,is a natural resource of cellulose. In this study,high-pressure homogenization assisted with acidolysis treatment was employed to produce BSS cellulose nanofiber（CNF）,and the structure was characterized by powder X-ray diffraction（XRD）,Fourier-transform infrared（FT-IR） spectroscopy,atomic force microscopy（AFM）,high resolution transmission electron microscopy（HTTEM）,thermogravimetric analysis（TGA）,and ^13 C nuclear magnetic resonance（NMR）. Moreover,the structure and properties of CNF were compared with those of BSS insoluble dietary fiber（IDF）. The results showed that CNF was in the form of a grid-like micro fiber,and its particle size was obviously reduced,while the crystallinity,thermal stability and solubility were increased. The results indicated that high-pressure homogenization assisted with acidolysis treatment was an effective method to prepare the BSS CNF,which could be a promising biopolymer reinforced material.

Octadecylamine Graft-modified Cellulose Nanofiber and Its Reinforcement to Poly(butylene adipate-co-terephthalate) Composites

Biodegradable polymers such as poly(butylene adipate-coterephthalate)(PBAT)have attracted great interest as alternatives to traditional petroleum-based polymers.Nonetheless,it is necessary to improve some properties of PBAT,such as mechanical strength.Cellulose nanofiber(CNF)can improve PBAT mechanical strength,but its dispersion and compatibility in the PBAT matrix require further improvement.In this study,octadecylamine(ODA)was utilized to graft-modify CNF to change the fiberto-fiber interaction and improve its compatibility with the PBAT matrix.PBAT composites with 1 wt%CNF were prepared using a masterbatch premixing method to avoid CNF aggregation during extrusion.The effects of ODA graft modification on CNF properties were studied;varying degrees of CNF modification were investigated for their effect on PBAT properties.ODA-modified CNF(OCNF)/PBAT melt-extruded composites possessing 17.2%higher tensile strength than pure PBAT polymer were obtained without affecting the thermal stability of PBAT.As a result,surface modification of CNF with ODA is an effective strategy for improving CNF-PBAT compatibility.

Structure and Mechanical Behavior of Cellulose Nanofiber and Micro-Fibrils by Molecular Dynamics Simulation

Cellulose nanofiber (CNF) and CNF micro-fibrils (CNF-MFs) are computationally modeled by molecular dynamics with united atom (UA) methodology of polymers. Structural stability and mechanical properties of these materials are focused on. Diffusion coefficient decreases with increase of the number of shells in CNF-MF. The structure of CNF-MFs with crystalline alignment is totally stabilized with twist which is an accumulation of torsion angles at Glycosidic bonds between monomers inside CNFs. Unique fiber drawing simulation, where a single CNF fiber is taken out of CNF-MF structure, is first conducted. The CNF fiber which is drawn out stretches up to relatively large strain, with linear increase of tensile stress. The computation results show that, the larger the number of shell structure of CNF-MF is, the larger the stretch and the stress of drawn fibers are.