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,bacteri...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.展开更多
Methyl methacrylate (MMA) was successfully grafted onto cellulose nanofibers (CNFs) at room temperature in an emulsion system using a diethyl(1,10-<span style="font-family:;" "=""><sp...Methyl methacrylate (MMA) was successfully grafted onto cellulose nanofibers (CNFs) at room temperature in an emulsion system using a diethyl(1,10-<span style="font-family:;" "=""><span style="font-family:Verdana;">phenanthroline </span><i><span style="font-family:Verdana;">N</span></i><sub><span style="font-family:Verdana;">1</span></sub><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;">N</span></i><sub><span style="font-family:Verdana;">10</span></sub><span style="font-family:Verdana;">)zinc(</span></span><span style="font-family:Verdana;">II</span><span style="font-family:Verdana;">) complex (Phen</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">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</span><span style="font-family:Verdana;"> using</span><span> Phen</span><span>-</span><span><span>DEZ and</span></span><span><span> O</span><sub><span>2</span></sub><span>.</span></span>展开更多
Lightweight,highly strong and bio-based structural materials remain a long-lasting challenge.Here,inspired by nacre,a lightweight and high mechanical performance cellulosic material was fabricated via a facile and eff...Lightweight,highly strong and bio-based structural materials remain a long-lasting challenge.Here,inspired by nacre,a lightweight and high mechanical performance cellulosic material was fabricated via a facile and effective top-down approach and the resulting material has a high tensile strength of149.21 MPa and toughness of 1.91 MJ/m^(3).More specifically,the natural balsawood(NW) was subjected to a simple chemical treatment,removing most lignin and partial hemicellulose,follow by freeze-drying,forming wood aerogel(WA).The delignification process produced many pores and exposed numerous aligned cellulose nanofibers.Afterwards,the WA absorbed a quantity of moisture and was directly densified to form above high-performance cellulosic material.Such treatment imitates highly ordered"brick-and-mortar" arrangement of nacre,in which water molecules plays the role of mortar and cellulose nanofibrils make the brick part.The lightweight and good mechanical properties make this material promising for new energy car,aerospace,etc.This paper also explains the strengthening mechanism for making biomimetic materials by water molecules-induced hydrogen bonding and will open a new path for designing high-performance bio-based structural materials.展开更多
UiO-66-NH2 is an efficient material for removing pollutants from wastewater due to its high specific surface area,high porosity and water stability.However,recycling them from wastewater is difficult.In this study,the...UiO-66-NH2 is an efficient material for removing pollutants from wastewater due to its high specific surface area,high porosity and water stability.However,recycling them from wastewater is difficult.In this study,the cellulose nanofibers mat deacetylated from cellulose acetate nanofibers were used to combine with UiO-66-NH_(2)by the method of in-situ growth to remove the toxic dye,rose bengal.Compared to previous work,the prepared composite could not only provide ease of separation of UiO-66-NH_(2)from the water after adsorption but also demonstrate better adsorption capacity(683 mg∙g‒1(T=25°C,pH=3))than that of the simple UiO-66-NH_(2)(309.6 mg∙g^(‒1)(T=25℃,pH=3)).Through the analysis of adsorption kinetics and isotherms,the adsorption for rose bengal is mainly suitable for the pseudo-second-order kinetic model and Freundlich model.Furthermore,the relevant research revealed that the main adsorption mechanism of the composite was electrostatic interaction,hydrogen bonding andπ–πinteraction.Overall,the approach depicts an efficient model for integrating metal-organic frameworks on cellulose nanofibers to improve metal-organic framework recovery performance with potentially broad applications.展开更多
In this study,cellulose nanofibers(CNFs)were crossed-linked with glutaraldehyde(GA)under acid condition for tailoring the mechanical properties and water-resistance of nanopaper or films.The impact of carboxyl content...In this study,cellulose nanofibers(CNFs)were crossed-linked with glutaraldehyde(GA)under acid condition for tailoring the mechanical properties and water-resistance of nanopaper or films.The impact of carboxyl content of CNFs,GA concentration,temperature,pH,and reaction time on the crosslinking was investigated,and the process conditions for the crosslinking were optimized.FT-IR analyses showed that CNFs/GA cross-linked nanopaper was successfully fabricated by acetalization between the-OH groups of CNFs and the-CHO groups of GA,resulting in the formation of a dense,three-dimensional network.The elastic modulus of CNFs/GA cross-linked film was 7.66GPa,62.98%higher than that of CNFs film.The water-resistance of the cross-linked CNFs/GA films was improved.The crossed-linked CNFs/GA films was still intact after 24 h after being immersed in water,while the CNFs films almost dissolved completely after 20 min of soaking in water.This method provides a facile route to enhance the elastic modulus and water-resistance of CNFs for potential applications including bullet-proof glass interlayer,flexible electronic device,and new packing materials.展开更多
Based on the functional properties of electrospun cellulose nanofibers(CNF),scientists are showing substantial interest to enhance the aesthetic properties.However,the lower color yield has remained a big challenge du...Based on the functional properties of electrospun cellulose nanofibers(CNF),scientists are showing substantial interest to enhance the aesthetic properties.However,the lower color yield has remained a big challenge due to the higher surface area of nanofibers.In this study,we attempted to improve the color yield properties of CNF by the pad-steam dyeing method.Neat CNF was obtained by deacetylation of electrospun cellulose acetate(CA)nanofibers.Three different kinds of reactive dyes were used and pad-steam dyeing parameters were optimized.SEM images revealed smooth morphology with an increase in the average diameter of nanofibers.FTIR results showed no change in the chemical structure after dyeing of CNF.Color fastness results demonstrated excellent ratings for reactive dyes,which indicate good dye fixation properties and no color loss during the washing process.The results confirm that the pad-steam dyeing method can be potentially considered to improve the aesthetic properties of CNF,which can be utilized for functional garments,such as breathable raincoats and disposable face masks.展开更多
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 sodi...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.展开更多
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...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.展开更多
Cellulose nanofibers(CNF)are considered to be a potential substrate of energy material for energy storage devices due to the foldable,lightweight,recyclable and environmentally friendly feature.However,the energy mate...Cellulose nanofibers(CNF)are considered to be a potential substrate of energy material for energy storage devices due to the foldable,lightweight,recyclable and environmentally friendly feature.However,the energy materials tend to distribute unevenly or fall off from CNF easily,resulting in the decrease of the devices’overall performance.Here,for the first time,we used quaternized chitosan(QCS)as stabilizer and adhesive to in situ synthesize and deposite copper sulfide nanocrystals(CuS-NCs)on CNF and further obtained the conductive paper for flexible supercapacitors.In the presence of QCS,CuS-NCs deposited in situ on CNF can be capped and stabilized by the QCS molecular chains for uniform distribution,which is conducive to the capacitive behavior and electrochemical stability of composite paper.The result shows that the specific capacitance of the composite paper was as high as 314.3 F/g at a current density of 1 A/g,a high rate capacitance of 252.6 F/g was achieved even at a high current density of 10 A/g.It reveals that the composite paper exhibited better electrochemical performance than many other CuS-based electrode materials for supercapacitor.More importantly,the composite paper performed well in various folding state without changing much electrochemical performance.Therefore,this work provides a novel strategy to in situ fabricate paper-based electrode for nextgeneration flexible energy-storage system.展开更多
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.Howev...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.展开更多
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 combina...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.展开更多
The demand for highly porous yet transparent aerogels with mechanical flexibility and solar-thermal dual-regulation for energy-saving windows is significant but challenging.Herein,a delaminated aerogel film(DAF)is fab...The demand for highly porous yet transparent aerogels with mechanical flexibility and solar-thermal dual-regulation for energy-saving windows is significant but challenging.Herein,a delaminated aerogel film(DAF)is fabricated through filtration-induced delaminated gelation and ambient drying.The delaminated gelation process involves the assembly of fluorinated cellulose nanofiber(FCNF)at the solid-liquid interface between the filter and the filtrate during filtration,resulting in the formation of lamellar FCNF hydrogels with strong intra-plane and weak interlayer hydrogen bonding.By exchanging the solvents from water to hexane,the hydrogen bonding in the FCNF hydrogel is further enhanced,enabling the formation of the DAF with intra-layer mesopores upon ambient drying.The resulting aerogel film is lightweight and ultra-flexible,which pos-sesses desirable properties of high visible-light transmittance(91.0%),low thermal conductivity(33 mW m^(-1) K^(-1)),and high atmospheric-window emissivity(90.1%).Furthermore,the DAF exhibits reduced surface energy and exceptional hydrophobicity due to the presence of fluorine-containing groups,enhancing its durability and UV resistance.Consequently,the DAF has demonstrated its potential as solar-thermal regulatory cooling window materials capable of simultaneously providing indoor lighting,thermal insulation,and daytime radiative cooling under direct sunlight.Significantly,the enclosed space protected by the DAF exhibits a temperature reduction of 2.6℃ compared to that shielded by conventional architectural glass.展开更多
Cellulose nanofiber(CNF)was isolated from Okara using deep eutectic solvent(DES)with high-speed stirring.The composite hydrogels obtained by using different proportions of CNF and sodium alginate(SA)had different prop...Cellulose nanofiber(CNF)was isolated from Okara using deep eutectic solvent(DES)with high-speed stirring.The composite hydrogels obtained by using different proportions of CNF and sodium alginate(SA)had different properties.The CNF/SA composite hydrogels were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy and tested for compression properties,rheological properties,water content,and swelling degree.Physical crosslinking between SA and Ca^(2+),and different degrees of hydrogen bond formation between SA and CNF were observed.The CNF/SA composite hydrogel have great potential as reinforcements in eco-friendly composite hydrogels for diverse applications.展开更多
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 o...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.展开更多
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 ...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.展开更多
Nanocellulose has served as an eye-catching nanomaterial for constructing advanced functional devices with renewability,light weight,flexibility,and environmental friendliness.In this study,Co_(3)O_(4)/graphene/cellul...Nanocellulose has served as an eye-catching nanomaterial for constructing advanced functional devices with renewability,light weight,flexibility,and environmental friendliness.In this study,Co_(3)O_(4)/graphene/cellulose nanofiber(CNF)flexible composite films,in which the CNF acted as a spacer for the graphene,were prepared via a facile and scalable vacuum filtration method.The effects of the CNF on the microstructure,hydrophilicity,thermal stability,tensile strength,surface resistance,and electrochemical performance of the Co_(3)O_(4)/graphene/CNF composite films were systematically investigated.The results showed that the synergistic interaction of the CNF and graphene substantially improved the overall properties of the Co_(3)O_(4)/graphene/CNF composite films,particularly their hydrophilicity and tensile strength.Meanwhile,Co_(3)O_(4)/graphene/CNF composite films with a CNF content of 4%appeared to have the optimal electrochemical performance,with an area specific capacitance of 56 mF/cm^(2) and prominent capacitance retention of 95.6%at a current density of 1 A/g after 1000 cycles.This work demonstrated that the prepared Co_(3)O_(4)/graphene/CNF flexible composite films have great application potential in the field of flexible energy storage devices.展开更多
The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal con...The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal conductivity and hydration.The results showed that with the addition of 0.7%by weight of NFC per emulsion in the presence of a cationic surfactant(CTAB).The new material produced presented a dry porosity between 4.7%and 4.4%,compressive strength between 9.8 and 22.9 MPa,and thermal conductivity between 0.95 and 2.25 W·m^(−1)·K^(−1).Thus we show better mechanical and thermal performance than that traditional Portland cement mortar with a density similar.In addition,the mortar made by emulsion of ordinary portland cement,cellulose nanofiber and organophilic clay(OC)treated with cetyltrimethylammonium bromide(CTAB)obtained has good resistance under high temperature and water,as well as excellent thermal insulation performance under high temperature and humidity conditions.This study verified that the presence of NFC promotes hydration,leading to the production of more calcium silicate and portlandite gel.展开更多
Carbon aerogels prepared from renewable nano building blocks are rising-star materials and hold great promise in many fields.However,various defects formed during carbonization at high temperature disfavor the stress ...Carbon aerogels prepared from renewable nano building blocks are rising-star materials and hold great promise in many fields.However,various defects formed during carbonization at high temperature disfavor the stress transfer and thus the fabrication of flexible carbon aerogel from renewable nano building blocks.Herein,a structural defect-reducing strategy is proposed by altering the pyrolysis route of cellulose nanofiber.Inorganic salt that inhibits the generation of tar volatilization during pyrolysis can prevent the formation of various structural defects.Microstructure with fewer defects can reduce stress concentration and remarkably enhance the compressibility of carbon aerogel,thus increasing the maximum stress retention of carbon aerogel.The carbon aerogel also has high stress sensor sensitivity and excellent temperature coefficient of resistance.The structural defect-reducing strategy will pave a new way to fabricate high-strength carbon materials for various fields.展开更多
Nanocellulose harvested from biomass has attractive properties that have promoted research on its practical applications.Herein,we investigated nanocellulose-based porous monoliths with oriented microchannels that can...Nanocellulose harvested from biomass has attractive properties that have promoted research on its practical applications.Herein,we investigated nanocellulose-based porous monoliths with oriented microchannels that can be fabricated via a unidirectional freezing method.In this method,water-dispersed cellulose nanofibers(CNFs)were immersed into a cold source at a controlled speed,followed by subsequent freeze-drying.The structure of porous cellulose monoliths mainly depends on two factors:the freezing conditions and properties of the dispersed CNFs.The former has been investigated previously.However,the effects of the latter remain unclear.In this study,CNF suspensions prepared by 2,2,6,6-tetramethylpiperidine-1-oxylmediated oxidation cellulose nanofibers(TOCNs)with different aspect ratios and concentrations were used.The effects of these variables on the resulting structure,including the pore shape,size,wall thickness,were examined.Based on the results,the impact of TOCNs on the structure of porous cellulose monoliths was investigated.Our findings suggested that depending on their structure,the porous cellulose monoliths exhibit different mechanical strengths and mass transport properties.In particular,porous cellulose monoliths synthesized from 5.1 wt.%short TOCNs exhibited a low density(55.9 mg∙cm^(−3)),high mechanical strength(8687 kPa),fast mass transport.展开更多
With the development of modern electronics,especially the next generation of wearable electromagnetic interference(EMI)shielding materials requires flexibility,ultrathin,lightweight and robustness to protect electroni...With the development of modern electronics,especially the next generation of wearable electromagnetic interference(EMI)shielding materials requires flexibility,ultrathin,lightweight and robustness to protect electronic devices from radiation pollution.In this work,the flexible and ultrathin dopamine modified MXene@cellulose nanofiber(DM@CNF)composite films with alternate multilayer structure have been developed by a facile vacuum filtration induced self-assembly approach.The multilayered DM@CNF composite films exhibit improved mechanical properties compared with the homogeneous DM/CNF film.By adjusting the layer number,the multilayered DM3@CNF2 composite film exhibits a tensile strength of 48.14 MPa and a toughness of 5.28 MJ·m^(–3) with a thickness about 19μm.Interestingly that,the DM@CNF film with annealing treatment achieves significant improvement in conductivity(up to 17264 S·m^(–1))and EMI properties(SE of 41.90 dB and SSE/t of 10169 dB·cm^(2)·g–1),which still maintains relatively high mechanical properties.It is highlighted that the ultrathin multilayered DM@CNF film exhibits superior EMI shielding performance compared with most of the metal-based,carbon-based and MXene-based shielding materials reported in the literature.These results will offer an appealing strategy to develop the ultrathin and flexible MXene-based materials with excellent EMI shielding performance for the next generation intelligent protection devices.展开更多
基金Open Project Program of Key Laboratory of Yarn Materials Forming and Composite Processing Technology of Zhejiang Province,China(No.MTC2020-10)。
文摘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.
文摘Methyl methacrylate (MMA) was successfully grafted onto cellulose nanofibers (CNFs) at room temperature in an emulsion system using a diethyl(1,10-<span style="font-family:;" "=""><span style="font-family:Verdana;">phenanthroline </span><i><span style="font-family:Verdana;">N</span></i><sub><span style="font-family:Verdana;">1</span></sub><span style="font-family:Verdana;">,</span><i><span style="font-family:Verdana;">N</span></i><sub><span style="font-family:Verdana;">10</span></sub><span style="font-family:Verdana;">)zinc(</span></span><span style="font-family:Verdana;">II</span><span style="font-family:Verdana;">) complex (Phen</span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;">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</span><span style="font-family:Verdana;"> using</span><span> Phen</span><span>-</span><span><span>DEZ and</span></span><span><span> O</span><sub><span>2</span></sub><span>.</span></span>
基金supported by the National Natural Science Foundation of China (No.51803093)National Science Foundation of Jiangsu Province (No.BK20180770)。
文摘Lightweight,highly strong and bio-based structural materials remain a long-lasting challenge.Here,inspired by nacre,a lightweight and high mechanical performance cellulosic material was fabricated via a facile and effective top-down approach and the resulting material has a high tensile strength of149.21 MPa and toughness of 1.91 MJ/m^(3).More specifically,the natural balsawood(NW) was subjected to a simple chemical treatment,removing most lignin and partial hemicellulose,follow by freeze-drying,forming wood aerogel(WA).The delignification process produced many pores and exposed numerous aligned cellulose nanofibers.Afterwards,the WA absorbed a quantity of moisture and was directly densified to form above high-performance cellulosic material.Such treatment imitates highly ordered"brick-and-mortar" arrangement of nacre,in which water molecules plays the role of mortar and cellulose nanofibrils make the brick part.The lightweight and good mechanical properties make this material promising for new energy car,aerospace,etc.This paper also explains the strengthening mechanism for making biomimetic materials by water molecules-induced hydrogen bonding and will open a new path for designing high-performance bio-based structural materials.
基金support of the Tianjin Natural Science Foundation(Grant No.18JCQNJC71900).
文摘UiO-66-NH2 is an efficient material for removing pollutants from wastewater due to its high specific surface area,high porosity and water stability.However,recycling them from wastewater is difficult.In this study,the cellulose nanofibers mat deacetylated from cellulose acetate nanofibers were used to combine with UiO-66-NH_(2)by the method of in-situ growth to remove the toxic dye,rose bengal.Compared to previous work,the prepared composite could not only provide ease of separation of UiO-66-NH_(2)from the water after adsorption but also demonstrate better adsorption capacity(683 mg∙g‒1(T=25°C,pH=3))than that of the simple UiO-66-NH_(2)(309.6 mg∙g^(‒1)(T=25℃,pH=3)).Through the analysis of adsorption kinetics and isotherms,the adsorption for rose bengal is mainly suitable for the pseudo-second-order kinetic model and Freundlich model.Furthermore,the relevant research revealed that the main adsorption mechanism of the composite was electrostatic interaction,hydrogen bonding andπ–πinteraction.Overall,the approach depicts an efficient model for integrating metal-organic frameworks on cellulose nanofibers to improve metal-organic framework recovery performance with potentially broad applications.
基金the State Key Laboratory of Pulp and Paper Engineering,South China University of Technology(Grant No.2015C09,2016PY01)Natural Science Foundation of Guangdong Province(Grant No.2016A030311052).
文摘In this study,cellulose nanofibers(CNFs)were crossed-linked with glutaraldehyde(GA)under acid condition for tailoring the mechanical properties and water-resistance of nanopaper or films.The impact of carboxyl content of CNFs,GA concentration,temperature,pH,and reaction time on the crosslinking was investigated,and the process conditions for the crosslinking were optimized.FT-IR analyses showed that CNFs/GA cross-linked nanopaper was successfully fabricated by acetalization between the-OH groups of CNFs and the-CHO groups of GA,resulting in the formation of a dense,three-dimensional network.The elastic modulus of CNFs/GA cross-linked film was 7.66GPa,62.98%higher than that of CNFs film.The water-resistance of the cross-linked CNFs/GA films was improved.The crossed-linked CNFs/GA films was still intact after 24 h after being immersed in water,while the CNFs films almost dissolved completely after 20 min of soaking in water.This method provides a facile route to enhance the elastic modulus and water-resistance of CNFs for potential applications including bullet-proof glass interlayer,flexible electronic device,and new packing materials.
基金This work was supported by the Key-Area Research and Development Program of Guangdong Province,China(No.2019B010941001)the Natural Science Foundation of Guangdong Province,China(No.2018A0303100022).
文摘Based on the functional properties of electrospun cellulose nanofibers(CNF),scientists are showing substantial interest to enhance the aesthetic properties.However,the lower color yield has remained a big challenge due to the higher surface area of nanofibers.In this study,we attempted to improve the color yield properties of CNF by the pad-steam dyeing method.Neat CNF was obtained by deacetylation of electrospun cellulose acetate(CA)nanofibers.Three different kinds of reactive dyes were used and pad-steam dyeing parameters were optimized.SEM images revealed smooth morphology with an increase in the average diameter of nanofibers.FTIR results showed no change in the chemical structure after dyeing of CNF.Color fastness results demonstrated excellent ratings for reactive dyes,which indicate good dye fixation properties and no color loss during the washing process.The results confirm that the pad-steam dyeing method can be potentially considered to improve the aesthetic properties of CNF,which can be utilized for functional garments,such as breathable raincoats and disposable face masks.
基金support of the Guangdong Basic and Applied Basic Research Foundation(grant nos.2020A1515110705 and 2021A1515110245)the China Postdoctoral Science Foundation(grant nos.2020M682711 and 2020M682710)+2 种基金the National Program for Support of Topnotch Young Professionals(grant no.x2qsA4210090)the National Natural Science Foundation of China(grant no.31971614)the State Key Laboratory of Pulp and Paper Engineering(grant no.2020C03).
文摘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.
基金funded by the Ministry of Business,Innovation and Employment Endeavour Fund of New Zealand(MAUX1801)supported by the China Postdoctoral Science Foundation(2021M692622).
文摘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.
基金This work was financially supported by this work was supported by State Key Laboratory of Pulp and Paper Engineering(No.2020ZR05)the National Natural Science Foundation of China(No.31622044)the project from and the Fundamental Research Funds for the Central Universities(No.2020ZYGXZR066).
文摘Cellulose nanofibers(CNF)are considered to be a potential substrate of energy material for energy storage devices due to the foldable,lightweight,recyclable and environmentally friendly feature.However,the energy materials tend to distribute unevenly or fall off from CNF easily,resulting in the decrease of the devices’overall performance.Here,for the first time,we used quaternized chitosan(QCS)as stabilizer and adhesive to in situ synthesize and deposite copper sulfide nanocrystals(CuS-NCs)on CNF and further obtained the conductive paper for flexible supercapacitors.In the presence of QCS,CuS-NCs deposited in situ on CNF can be capped and stabilized by the QCS molecular chains for uniform distribution,which is conducive to the capacitive behavior and electrochemical stability of composite paper.The result shows that the specific capacitance of the composite paper was as high as 314.3 F/g at a current density of 1 A/g,a high rate capacitance of 252.6 F/g was achieved even at a high current density of 10 A/g.It reveals that the composite paper exhibited better electrochemical performance than many other CuS-based electrode materials for supercapacitor.More importantly,the composite paper performed well in various folding state without changing much electrochemical performance.Therefore,this work provides a novel strategy to in situ fabricate paper-based electrode for nextgeneration flexible energy-storage system.
基金support from the Jiangsu Agriculture Science and Technology Innovation Fund(CX(20)3054)the Natural Science Foundation of Jiangsu Province(BK20200776)+1 种基金the Jiangsu Specially Appointed Professor Program,the Jiangsu Graduate Scientific Research Innovation Project(163020256)the National Natural Science Foundations of China(52073305).
文摘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.
基金support from Louisiana Board of Regents[LEQSF(2020-23)-RD-B-02,LEQSF(2018-19)-ENH-DE-06]Key Biomass Energy Laboratory of Henan Province(190506006 and 200606004)National Institute of Forest Science(Seoul,Korea)。
文摘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.
基金The authors are grateful for the financial support from the National Natural Science Foundation of China(Grant Nos.52273067,52122303,52233006)the Fundamental Research Funds for the Central Universities(Grant No.2232023A-03)the Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(23SG29).
文摘The demand for highly porous yet transparent aerogels with mechanical flexibility and solar-thermal dual-regulation for energy-saving windows is significant but challenging.Herein,a delaminated aerogel film(DAF)is fabricated through filtration-induced delaminated gelation and ambient drying.The delaminated gelation process involves the assembly of fluorinated cellulose nanofiber(FCNF)at the solid-liquid interface between the filter and the filtrate during filtration,resulting in the formation of lamellar FCNF hydrogels with strong intra-plane and weak interlayer hydrogen bonding.By exchanging the solvents from water to hexane,the hydrogen bonding in the FCNF hydrogel is further enhanced,enabling the formation of the DAF with intra-layer mesopores upon ambient drying.The resulting aerogel film is lightweight and ultra-flexible,which pos-sesses desirable properties of high visible-light transmittance(91.0%),low thermal conductivity(33 mW m^(-1) K^(-1)),and high atmospheric-window emissivity(90.1%).Furthermore,the DAF exhibits reduced surface energy and exceptional hydrophobicity due to the presence of fluorine-containing groups,enhancing its durability and UV resistance.Consequently,the DAF has demonstrated its potential as solar-thermal regulatory cooling window materials capable of simultaneously providing indoor lighting,thermal insulation,and daytime radiative cooling under direct sunlight.Significantly,the enclosed space protected by the DAF exhibits a temperature reduction of 2.6℃ compared to that shielded by conventional architectural glass.
基金This work was supported by the Foundation of State Key Laboratory of Pulp and Paper Engineering(201819)the project of Shaanxi Provincial Department of Education Key Laboratory Research Open Fund(Grant No.17JS017)the Project of Shaanxi University of Science and Technology Research Initial Fund(Grant No.BJ15-29).
文摘Cellulose nanofiber(CNF)was isolated from Okara using deep eutectic solvent(DES)with high-speed stirring.The composite hydrogels obtained by using different proportions of CNF and sodium alginate(SA)had different properties.The CNF/SA composite hydrogels were analyzed using Fourier transform infrared spectroscopy and scanning electron microscopy and tested for compression properties,rheological properties,water content,and swelling degree.Physical crosslinking between SA and Ca^(2+),and different degrees of hydrogen bond formation between SA and CNF were observed.The CNF/SA composite hydrogel have great potential as reinforcements in eco-friendly composite hydrogels for diverse applications.
基金financial support from the National Key Research and Development Program of China (Grant Nos. 2017YFB0307901 and 2017YFE010 2500)
文摘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.
文摘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.
基金This work was financially supported by the National Natural Science Foundation of China(grant no.22078306)Key Research and Development Program of Zhejiang Province(grant no.2020C02021)+1 种基金521 Talent Cultivation Program of Zhejiang Sci-Tech University(grant no.11110132521310)Qujiang Science and Technology Project(grant no.QJ2020023).
文摘Nanocellulose has served as an eye-catching nanomaterial for constructing advanced functional devices with renewability,light weight,flexibility,and environmental friendliness.In this study,Co_(3)O_(4)/graphene/cellulose nanofiber(CNF)flexible composite films,in which the CNF acted as a spacer for the graphene,were prepared via a facile and scalable vacuum filtration method.The effects of the CNF on the microstructure,hydrophilicity,thermal stability,tensile strength,surface resistance,and electrochemical performance of the Co_(3)O_(4)/graphene/CNF composite films were systematically investigated.The results showed that the synergistic interaction of the CNF and graphene substantially improved the overall properties of the Co_(3)O_(4)/graphene/CNF composite films,particularly their hydrophilicity and tensile strength.Meanwhile,Co_(3)O_(4)/graphene/CNF composite films with a CNF content of 4%appeared to have the optimal electrochemical performance,with an area specific capacitance of 56 mF/cm^(2) and prominent capacitance retention of 95.6%at a current density of 1 A/g after 1000 cycles.This work demonstrated that the prepared Co_(3)O_(4)/graphene/CNF flexible composite films have great application potential in the field of flexible energy storage devices.
文摘The objective of this study is to analyze the effects of using surfactant(CTAB)and cellulose nanofibers(NFC)as an admixture in cement mortars.We examined composite properties as porosity,compression energy,thermal conductivity and hydration.The results showed that with the addition of 0.7%by weight of NFC per emulsion in the presence of a cationic surfactant(CTAB).The new material produced presented a dry porosity between 4.7%and 4.4%,compressive strength between 9.8 and 22.9 MPa,and thermal conductivity between 0.95 and 2.25 W·m^(−1)·K^(−1).Thus we show better mechanical and thermal performance than that traditional Portland cement mortar with a density similar.In addition,the mortar made by emulsion of ordinary portland cement,cellulose nanofiber and organophilic clay(OC)treated with cetyltrimethylammonium bromide(CTAB)obtained has good resistance under high temperature and water,as well as excellent thermal insulation performance under high temperature and humidity conditions.This study verified that the presence of NFC promotes hydration,leading to the production of more calcium silicate and portlandite gel.
基金the National Natural Science Foundation of China(Nos.32201499,22208069 and 32071714)Guangdong Basic and Applied Basic Research Foundation(No.2021A1515110205)+1 种基金Fundamental Research Funds for the Central Universities(No.2022ZYGXZR019)the State Key Laboratory of Pulp&Paper Engineering(No.2022C01).
文摘Carbon aerogels prepared from renewable nano building blocks are rising-star materials and hold great promise in many fields.However,various defects formed during carbonization at high temperature disfavor the stress transfer and thus the fabrication of flexible carbon aerogel from renewable nano building blocks.Herein,a structural defect-reducing strategy is proposed by altering the pyrolysis route of cellulose nanofiber.Inorganic salt that inhibits the generation of tar volatilization during pyrolysis can prevent the formation of various structural defects.Microstructure with fewer defects can reduce stress concentration and remarkably enhance the compressibility of carbon aerogel,thus increasing the maximum stress retention of carbon aerogel.The carbon aerogel also has high stress sensor sensitivity and excellent temperature coefficient of resistance.The structural defect-reducing strategy will pave a new way to fabricate high-strength carbon materials for various fields.
基金JSPS KAKENHI(No.22K18047)JST SICORP(No.JPMJSC2112)the New Energy and Industrial Technology Development Organization(NEDO)(No.JPNP20004)。
文摘Nanocellulose harvested from biomass has attractive properties that have promoted research on its practical applications.Herein,we investigated nanocellulose-based porous monoliths with oriented microchannels that can be fabricated via a unidirectional freezing method.In this method,water-dispersed cellulose nanofibers(CNFs)were immersed into a cold source at a controlled speed,followed by subsequent freeze-drying.The structure of porous cellulose monoliths mainly depends on two factors:the freezing conditions and properties of the dispersed CNFs.The former has been investigated previously.However,the effects of the latter remain unclear.In this study,CNF suspensions prepared by 2,2,6,6-tetramethylpiperidine-1-oxylmediated oxidation cellulose nanofibers(TOCNs)with different aspect ratios and concentrations were used.The effects of these variables on the resulting structure,including the pore shape,size,wall thickness,were examined.Based on the results,the impact of TOCNs on the structure of porous cellulose monoliths was investigated.Our findings suggested that depending on their structure,the porous cellulose monoliths exhibit different mechanical strengths and mass transport properties.In particular,porous cellulose monoliths synthesized from 5.1 wt.%short TOCNs exhibited a low density(55.9 mg∙cm^(−3)),high mechanical strength(8687 kPa),fast mass transport.
基金supported by the National Key Research and Development Program of China(No.2022YFB3807200)the National Natural Science Foundation of China(Nos.52201022 and 21973012)+1 种基金the Natural Science Foundation of Fujian Province(Nos.2020J01474,2021J06011,and 2020J01351)the“Qishan Scholar”Scientific Research Startup Project of Fuzhou University.
文摘With the development of modern electronics,especially the next generation of wearable electromagnetic interference(EMI)shielding materials requires flexibility,ultrathin,lightweight and robustness to protect electronic devices from radiation pollution.In this work,the flexible and ultrathin dopamine modified MXene@cellulose nanofiber(DM@CNF)composite films with alternate multilayer structure have been developed by a facile vacuum filtration induced self-assembly approach.The multilayered DM@CNF composite films exhibit improved mechanical properties compared with the homogeneous DM/CNF film.By adjusting the layer number,the multilayered DM3@CNF2 composite film exhibits a tensile strength of 48.14 MPa and a toughness of 5.28 MJ·m^(–3) with a thickness about 19μm.Interestingly that,the DM@CNF film with annealing treatment achieves significant improvement in conductivity(up to 17264 S·m^(–1))and EMI properties(SE of 41.90 dB and SSE/t of 10169 dB·cm^(2)·g–1),which still maintains relatively high mechanical properties.It is highlighted that the ultrathin multilayered DM@CNF film exhibits superior EMI shielding performance compared with most of the metal-based,carbon-based and MXene-based shielding materials reported in the literature.These results will offer an appealing strategy to develop the ultrathin and flexible MXene-based materials with excellent EMI shielding performance for the next generation intelligent protection devices.