This study focuses on the extraction of cellulose nanocrystals (CNC), from microcrystalline cellulose (MCC), derived from Ayous sawdust. The process involves multiple steps and a large amount of chemical products. The...This study focuses on the extraction of cellulose nanocrystals (CNC), from microcrystalline cellulose (MCC), derived from Ayous sawdust. The process involves multiple steps and a large amount of chemical products. The objective of this research was to determine the effects of factors that impact the isolation process and to identify the optimal conditions for CNC isolation by using the response surface methodology. The factors that varied during the process were the quantity of MCC, the concentration of sulfuric acid, the hydrolysis time and temperature, and the ultrasonic treatment time. The response measured was the yield. The study found that with 5.80 g of microcrystalline cellulose, a sulfuric acid concentration of 63.50% (w/w), a hydrolysis time of 53 minutes, a hydrolysis temperature of 69˚C, and a sonication time of 19 minutes are the ideal conditions for isolation. The experimental yield achieved was (37.84 ± 0.99) %. The main factors influencing the process were the sulfuric acid concentration, hydrolysis time and temperature, with a significant influence (p < 0.05). Infrared characterization results showed that nanocrystals were indeed isolated. With a crystallinity of 35.23 and 79.74, respectively, for Ayous wood fiber and nanocrystalline cellulose were observed by X-ray diffraction, with the formation of type II cellulose, thermodynamically more stable than native cellulose type I.展开更多
Polypyrrole(PPy)is wildly used as electrode material in supercapacitors due to its high conductivity,low cost,ease of handling,and ease of fabrication.However,limited capacitance and poor cycling stability hinder its ...Polypyrrole(PPy)is wildly used as electrode material in supercapacitors due to its high conductivity,low cost,ease of handling,and ease of fabrication.However,limited capacitance and poor cycling stability hinder its practical application.After developing carboxylated cellulose nanocrystals(CNC-COO^(-))as immobile dopants for PPy to improve its cycling stability,we investigated the effect of different commonly used salts(KCl,NaCl,KBr,and NaClO_(4))as dopants during electrode fabrication by electropolymerization.The film’s capacitance increased from 160.6 to 183.4 F g^(-1)after adding a combination of KCl and NaClO_(4) into the electrodeposition electrolyte.More importantly,the porous and interconnected PPy/CNC-COO^(-)-Cl-(Cl O_(4)^(-))_0.5 electrode film exhibited an excellent capacitance of 125.0 F g^(-1)(0.78 F cm^(-2))at a high current density of 2.0 Ag^(-1)(20 m A cm^(-2),allowing charging in less than 1 min),increasing almost 204%over PPy/CNC-COO-films.A symmetric PPy/CNC-COO^(-)-Cl-(ClO_(4)^(-))_0.5 supercapacitor retained its full capacitance after 5000 cycles,and displayed a high energy density of 5.2 Wh kg^(-1)at a power density of 25.4 W kg^(-1)(34.5μWh cm^(-2) at 1752.3μW cm^(-2)).These results reveal that the porous structure formed by doping with CNC-COO-and inorganic salts opens up more active reaction areas to store charges in PPy-based films as the stiff and ribbon-like CNC-COO-as permanent dopants improve the strength and stability of PPy-based films.Our demonstration provides a simple and practical way to deposit PPy based supercapacitors with high capacitance,fast charging,and excellent cycling stability.展开更多
Nanocellulose,a natural polymeric nanomaterial,has attracted significant attention in enhanced oil recovery(EOR)applications due to its abundance,nanoscale,high oil-water interfacial adsorption ef-ficiency.In this stu...Nanocellulose,a natural polymeric nanomaterial,has attracted significant attention in enhanced oil recovery(EOR)applications due to its abundance,nanoscale,high oil-water interfacial adsorption ef-ficiency.In this study,surface-functionalized cellulose nanocrystals(SF-CNCs)were prepared via hy-drochloric acid hydrolysis and chemical modification,with adaptable nanosize and considerable dispersion stability in low-permeability reservoirs.The SF-CNCs were structurally characterized by FT-IR,Cryo-TEM,which have a diameter of 5-10 nm and a length of 100-200 nm.The SF-CNC dispersions possessed higher stability and stronger salt-tolerance than those of corresponding CNC dispersions,due to the strong hydrophilicity of the sulfonic acid group.It was synergistically used with a non-ionic surfactant(APG1214)to formulate a combined flooding system(0.1 wt%SF-CNC+0.2 wt%APG1214).The combined flooding system exhibits strong emulsification stability,low oil-water interfacial tension of o.03 mN/m,and the ability to alter the wettability for oil-wetting rocks.Furthermore,the combined system was_able to provide an optimum EOR efficiency of 20.2%in low-permeability cores with 30.13×10^(-3)μm^(2).Notably.it can enlarge the sweep volume and increase the displacement efficiency simultaneously.Overall,the newly formulated nanocellulose/surfactant combined system exhibits a remarkable EoR performance in low-permeability reservoirs.展开更多
Cellulose nanocrystals(CNCs) have been widely applied in biomaterials and show great biocompatibility and mechanical strength. In this review, the chemical reactions applied in CNC surface modification and their appli...Cellulose nanocrystals(CNCs) have been widely applied in biomaterials and show great biocompatibility and mechanical strength. In this review, the chemical reactions applied in CNC surface modification and their application in CNC based biomaterials are introduced. Furthermore, the conjugation of different functional molecules and nanostructures to the surface of CNCs are discussed, with focus on the binding modes, reaction conditions, and reaction mechanisms. With this introduction, we hope to provide a clear view of the strategies for surface modification of CNCs and their application in biomaterials, thus providing an overall picture of promising CNC-based biomaterials and their production.展开更多
As the world's population exponentially grows,so does the need for the production of food,with cereal production growing annually from an estimated 1.0 billion to 2.5 billion tons within the last few decades.This ...As the world's population exponentially grows,so does the need for the production of food,with cereal production growing annually from an estimated 1.0 billion to 2.5 billion tons within the last few decades.This rapid growth in food production results in an ever increasing amount of agricultural wastes,of which already occupies nearly 50%of the total landfill area.For example,is the billions of dry tons of cellulose-containing spent coffee grounds disposed in landfills annually.This paper seeks to provide a method for isolating cellulose nanocrystals(CNCs)from spent coffee grounds,in order to recycle and utilize the cellulosic waste material which would otherwise have no applications.CNCs have already been shown to have vast applications in the polymer engineering field,mainly utilized for their high strength to weight ratio for reinforcement of polymer-based nanocomposites.A successful method of purifying and hydrolyzing the spent coffee grounds in order to isolate usable CNCs was established.The CNCs were then characterized using current techniques to determine important chemical and physical properties.A few crucial properties determined were aspect ratio of 12±3,crystallinity of 74.2%,surface charge density of(48.4±6.2)mM/kg cellulose,and the ability to successfully reinforce a polymer based nanocomposite.These characteristics compare well to other literature data and common commercial sources of CNCs.展开更多
In this work,nine different types of edible coating based on pectin,cellulose nanocrystals,glycerol,and essential oil of lemongrass were prepared and used to coat strawberries with a film formed directly on the surfac...In this work,nine different types of edible coating based on pectin,cellulose nanocrystals,glycerol,and essential oil of lemongrass were prepared and used to coat strawberries with a film formed directly on the surface of the coated fruit.The effects of the different edible coatings on refrigerated fruits in terms of weight loss,titratable acidity,total soluble solids,pH,and anthocyanin content was evaluated after 2 days,4 days,6 days,and 8 days of storage.Application of the edible coatings reduced the weight loss of the coated strawberries and the anthocyanin content.The total soluble solids content of or uncoated fruit increase more markedly than that of coated fruit.In contrast,pH was maintained for both coated and uncoated strawberries.The edible coatings were effective in minimizing of the weight loss,without worsening the physical chemistry attributes.The treatments T5 and T9 presented the best results.展开更多
Agricultural waste straw is the renewable resource with the highest annual yield in the world.In value-added applications of agricultural waste,dicarboxyl cellulose nanocrystals(DCCs)are prepared from rice,wheat,and c...Agricultural waste straw is the renewable resource with the highest annual yield in the world.In value-added applications of agricultural waste,dicarboxyl cellulose nanocrystals(DCCs)are prepared from rice,wheat,and corn straw by sequential periodate-chlorite oxidation.In this study,DCCs from rice,wheat,and corn straw were characterized by transmission electron microscopy(TEM),Fourier transform infrared spectrometer,X-ray diffractometer(XRD),and thermal gravimetric analysis(TGA).The carboxyl content of the DCCs was also investigated.XRD results show that the crystallinity index decreased after sequential periodate-chlorite oxidation;however,the cellulose I structure was maintained.TEM results show that rod-shaped DCCs with an average length and width of 287.0 nm and 9.9 nm,respectively,were successfully prepared by sequential periodate-chlorite oxidation.The carboxyl content of the DCCs was around 3.9 mmol/g,and not affected by the type of straw.Experiments to study the removal of copper ions in aqueous medium were performed with the prepared DCCs.The adsorption capacities of copper ions were 131,162,and 144 mg/g for DCCs prepared from rice,wheat,and corn straws,respectively.The results show that DCCs prepared from rice,wheat,and corn straws by sequential periodatechlorite oxidation have potential for the removal of copper ions from aqueous medium.展开更多
Chiroptical materials are widely used in photonic devices,enantioselective catalysis and bio-sensors.Cellulose-base chiroptical materials with multilength scale structural hierarchy and unique light manipulation abili...Chiroptical materials are widely used in photonic devices,enantioselective catalysis and bio-sensors.Cellulose-base chiroptical materials with multilength scale structural hierarchy and unique light manipulation ability found in nature provide inspiration for materials design.Cellulose nanocrystals(CNC)display twisted rod morphology and hierarchical chirality.Leveraging the evaporation-induced self-assembly of negatively charged CNC,a broad realm of CNC-based chiroptical materials featuring one-dimensional photonic bandgap and novel chiroptical properties have been developed,which are of scientific and technological significance.Here we presented a brief overview on CNC-based chiroptical materials by evaporation-induced self-assembly,showed energy and chirality transfer in a host-guest environment leading to photonic bandgap modulation of optoelectronic properties,outlined novel chiroptical phenomena and their underlying principles,and demonstrated the application potentials of the CNC-based chiroptical materials.展开更多
With excellent biocompatibility and unique physiochemical properties,nanocelluloses including cellulose nanocrystals(CNCs)and cellulose nanofibrils(CNFs)are promising candidates for preparing biomedical hydrogels.CNCs...With excellent biocompatibility and unique physiochemical properties,nanocelluloses including cellulose nanocrystals(CNCs)and cellulose nanofibrils(CNFs)are promising candidates for preparing biomedical hydrogels.CNCs and CNFs are different in morphology and surface charges.Herein,CNCs and two CNFs(CNFs-C,Carboxylated CNFs;CNFs-P,Phosphorylated CNFs)were synthesized and applied to fabricate hydrogels through metal crosslinking.Aluminum crosslinking was found to be the best choice for enhancing the strength.This study systematically compared the morphologies,storage modulus,loss factor,continuous shear ramp,self-healing,swelling,in vitro degradation and injectable properties of the fabricated hydrogels,Further,a radar chart is summarized as guidelines to direct the rational selection to meet the specific requirements of further biomedical applications.At the same nanocellulose concentration and after Al^(3+)crosslinking,CNCs hydrogels had strong water holding capacity twice as much as that of CNFs hydrogels.While CNFs hydrogels showed higher hardness and stronger resistance to degradation than that of CNCs.These results provide detailed insights into nanocellulose hydrogels,making it possible to use these guidelines to select hydrogels for desired performance.展开更多
Porous three-dimensional (3D) structures generally improve the performance of electrodes by increasing their active surface area and the diffusion speed of electrolyte ions during charging/discharging.Threedimensional...Porous three-dimensional (3D) structures generally improve the performance of electrodes by increasing their active surface area and the diffusion speed of electrolyte ions during charging/discharging.Threedimensional polypyrrole (PPy) based films were created by electrodepositing PPy in the presence of varying amounts of chloride anions (Cl^(-)) and polyanionic ribbonlike nanoparticles (carboxylated cellulose nanocrystals (CNC-COO-)) as scaffold material.The assembly mechanism of the 3D PPy electrodes combines the effect of different nucleation and growth mechanisms during electropolymerization and deposition of the formed PPy with CNC-COO-and with Cl^(-).The highest area capacitance of these electrode materials was 1.39 F cm^(-2)(150.2 F g^(-1)) at a current density of 1 m A cm^(-2)(0.1 A g^(-1)).More importantly,at a high current density of 20 m A cm^(-2)(2.2 A g^(-1)),the thick (ca.130μm),3D,and high mass loading(9.2 mg cm^(-2)) Cl^(-):CNC-COO-/PPy films exhibited an excellent areal capacitance of 0.85 F cm^(-2)(70.8 F g^(-1)),increasing about 16%over CNC-COO-/PPy films prepared without Cl^(-)present during electrodeposition.In addition,an aqueous Cl^(-):CNC-COO-/PPy (with Cl^(-):CNC-COO-=2.0) symmetric supercapacitor had an outstanding energy density of 41.15μWh cm^(-2)(4.46 Wh kg^(-1)) and excellent cycling stability,while even improving on its original areal capacitance (to 111.2%of its original capacitance) after cycling3000 cycles at 8 m A cm^(-2),indicating their potential in energy storage devices.展开更多
The aim of this work was to use cellulose nanocrystals that were obtained by hydrolysis in phosphoric acid solution and further modified with succinic anhydride in the microwave field for PLA reinforcement.A series of...The aim of this work was to use cellulose nanocrystals that were obtained by hydrolysis in phosphoric acid solution and further modified with succinic anhydride in the microwave field for PLA reinforcement.A series of allbionanocomposites containing unmodified and surface modified cellulose nanocrystals with CNC content in the range of 1–3%_(w.t.) were obtained by melt blending and tested by XRD,SEM,DSC and DMA to investigate the effect of surface esterification of CNCs on the structure,morphology,dynamic mechanical properties of bionanocomposites,as well as phase transitions of PLA in the presence of cellulosic nanofiller.DMA investigations showed the highest increase of storage modulus by ca.7%(335 MPa at 25℃)in the glassy state of PLA for 2%_(w.t.)of unmodified CNC.Though,addition of 2%_(w.t.)of succinylated CNCs caused the highest increase of the onset of glass transition temperature(by 6.2℃)thus widening the temperature range of biocomposite application.The increase of glass transition temperature indicates the strongest interfacial interactions due to improved miscibility of surface modified nanocrystals and thus good dispersion of additive in PLA matrix providing high interface.展开更多
Acid mine drainage presents an important threat to cementitious structures.This study is aimed at investigating the effect of cellulose nanocrystals(CNCs)on the acid resistance of cementitious composites.CNCs were add...Acid mine drainage presents an important threat to cementitious structures.This study is aimed at investigating the effect of cellulose nanocrystals(CNCs)on the acid resistance of cementitious composites.CNCs were added to mortar mixtures as additives at cement volume ratios of 0.2vol%,0.4vol%,1.0vol%,and 1.5vol%.After 28 d of standard curing,the samples were immersed in a sulfuric acid with a pH value of 2 for 75 d.The unconfined compressive strength(UCS)test,the density,water absorption,void volume test,and thermogravimetric analysis were carried out to investigate the properties of CNC mixtures before sulfuric acid immersion.It was found that the addition of CNC reduced the volume of permeable voids and increased the hydration degree and mechanical strength of the samples.Changes in mass and length were monitored during immersion to evaluate the acid resistance of mixtures.The mixture with 0.4vol%CNC showed a reduced mass change and length change indicating its improved acid resistance.展开更多
Rheometer and differential scanning calorimetry (DSC) have been used to probe the mechanism of gelation in gels formed by mixture of k-carrageenan and cellulose nanocrystals (CNC). The results indicated that an as...Rheometer and differential scanning calorimetry (DSC) have been used to probe the mechanism of gelation in gels formed by mixture of k-carrageenan and cellulose nanocrystals (CNC). The results indicated that an association occurred between CNC chains and aggregated k-carrageenan helices.展开更多
Although nanocomposites have recently attracted special interest in the tissue engineering area,due to their potential to reinforce scaffolds for hard tissues applications,a number of variables must be set prior to an...Although nanocomposites have recently attracted special interest in the tissue engineering area,due to their potential to reinforce scaffolds for hard tissues applications,a number of variables must be set prior to any clinical application.This manuscript addresses the evaluation of thermo-mechanical properties and of cell proliferation of cellulose nanocrystals(CNC),poly(butylene adipate-co-terephthalate)(PBAT),poly(ε-caprolactone)(PCL)films and their bionanocomposites with 2 wt% of CNC obtained by casting technique.Cellulose nanocrystals extracted from Balsa wood by acid hydrolysis were used as a reinforcing phase in PBAT and PCL matrix films.The films and pure CNC at different concentrations were cultured with osteoblasts MG-63 and the cell proliferation was assessed by AlamarBlue?assay.The thermal-mechanical properties of the films were evaluated by dynamic-mechanical thermal analysis(DMTA).It was found by DMTA that the CNC acted as reinforcing agent.The addition of CNCs in the PBAT and PCL matrices induced higher storage moduli due to the reinforcement effects of CNCs.The cell viability results showed that neat CNC favored osteoblast proliferation and both PBAT and PCL films incorporated with CNC were biocompatible and supported cell proliferation along time.The nature of the polymeric matrix or the presence of CNC practically did not affect the cell proliferation,confirming they have no in vitro toxicity.Such features make cellulose nanocrystals a suitable candidate for the reinforcement of biodegradable scaffolds for tissue engineering and biomedical applications.展开更多
The biocomposite films were prepared from poly(L-lactic acid)and cellulose nanocrystals.To improve interfacial compatibility of hydrophilic cellulose nanocrystals with hydrophobic matrix polymer as well as to provide ...The biocomposite films were prepared from poly(L-lactic acid)and cellulose nanocrystals.To improve interfacial compatibility of hydrophilic cellulose nanocrystals with hydrophobic matrix polymer as well as to provide the osteoconductive properties,cellulose was functionalized with poly(glutamic acid).The modified cellulose nanocrystals were better distributed and less aggregated within the matrix,which was testified by scanning electron,optical and polarized light microscopy.According to mechanical tests,composites filled with nanocrystals modified with PGlu demonstrated higher values of Young’s modulus,elongation at break and tensile strength.Incubation of composite materials in model buffer solutions for 30 weeks followed with staining of Ca^(2+)deposits with Alizarin Red S assay testified better mineralization of materials containing PGlu-modified cellulose nanocrystals as filler.As the result of in vivo experiment,the developed composite materials showed less level of inflammation in comparison with pure polymer matrix and composites filled with non-functionalized cellulose nanocrystals.展开更多
In this work,we studied the adsorption of modified cellulose nanocrystals onto solid surfaces by quartz crystal microbalance with dissipation monitoring(QCM-D).Cellulose nanocrystals obtained from tunicate(CNC)were mo...In this work,we studied the adsorption of modified cellulose nanocrystals onto solid surfaces by quartz crystal microbalance with dissipation monitoring(QCM-D).Cellulose nanocrystals obtained from tunicate(CNC)were modified at reducing end by amidation reactions.Two different functionalities were investigated:a polyamine dendrimer(CNC-NH_(2)),which interacts with gold surface by the amine groups;and a biotin moiety(CNC-Biot),which has a strong affinity for the protein streptavidin(SAV).QCM-D results revealed different adsorption behaviors between modified and unmodified CNCs.Hence,unmodified CNCs covered almost all the surface forming a rigid and flat layer whereas reducing end modified CNCs remained rather upright forming a hydrated and viscoelastic layer with lower surface coverage.The analysis of adsorption kinetics allowed the calculation of an apparent collision rate factor,which resulted 10-fold higher for unmodified CNCs compared to reducing end modified CNCs,therefore,demonstrating the different adsorption behavior.展开更多
Cellulose nanocrystal(CNC)is a biomaterial derived from plant lignocellulosic components,widely applied in various industrial fields.Concurrently,with the growth of awareness in developing green nanomaterial,the explo...Cellulose nanocrystal(CNC)is a biomaterial derived from plant lignocellulosic components,widely applied in various industrial fields.Concurrently,with the growth of awareness in developing green nanomaterial,the explored Washingtonia fibre could be alternative biomass for obtaining CNC products.In the present work,different acid concentrations of 5%,15%,and 25%hydrochloric solutions were employed to produce CNCs from Washingtonia fibre.With the chemical treatments,the yield of the CNC product was successfully retained at 21.6%-25.1%.Individually separated and needle-shaped CNC particles could be observed under the microscopic viewing with the increased acid concentrations.From elemental analysis,a relatively pure cellulose compartment was produced for all CNC samples.The zeta potential values between-10 to-16 mV proved that each nanoparticle sample possessed dispersion ability within an aqueous solution.Meanwhile,the degree of crystallinity and the thermal behavior of CNCs were enhanced with the increased acidic concentrations.Hence,the isolated CNCs(with 15%)from Washingtonia fibre lead a CNC with the highest aspect ratio(30).This parameter is so important that these structures show empowering points of view as nanomaterials for reinforced polymer composites,and it could be a reliable nano-filler for the composite fabrication process in the future.展开更多
The cellulose nanocrystals/graphene composite aerogel(CGA)and polyvinyl alcohol/cellulose nanocrystals/graphene composite aerogel(PCGA)were prepared by suspension titration,tert-butanol solution replacement and freeze...The cellulose nanocrystals/graphene composite aerogel(CGA)and polyvinyl alcohol/cellulose nanocrystals/graphene composite aerogel(PCGA)were prepared by suspension titration,tert-butanol solution replacement and freeze-drying successively.The removal rates of methyl blue(MB)from water by CGA and PCGA were evaluated and the effects of additions,adsorption time,reaction temperature and pH value of CGA and PCGA on MB removal rate were discussed.It was found that the optimal concentrations of both CGA and PCGA were 2 g∙L-1 in the adsorption reaction process and the adsorption equilibrium was reached within 120 min.The higher the initial pH value of MB solution is,the better the removal effect will be.The adsorption kinetics conformed to the pseudo-second-order kinetic model.The langmuir isothermal adsorption equation showed the maximum adsorption capacities of CGA and PCGA were 125 mg∙g-1 and 110.9 mg∙g-1,respectively.Under the conditions of adsorption time of 120 min,reaction temperature of 323 K,and initial MB solution pH value of 11,both CGA and PCGA had higher removal rates of MB,reaching more than 98%.展开更多
Plant components are an inexhaustible source for the construction of bio-based materials.Here we report,for the first time,the elaboration of biobased cellulose nanocrystals(CNC)/xyloglucan(XG)hydrogels.XG is a hemice...Plant components are an inexhaustible source for the construction of bio-based materials.Here we report,for the first time,the elaboration of biobased cellulose nanocrystals(CNC)/xyloglucan(XG)hydrogels.XG is a hemicellulose displaying a great affinity for cellulose surface and can be thus irreversibly adsorbed on CNC.Properties of the hydrogels were investigated by varying the molar mass of XG either by enzymatic treatment with Endo-glucanase(EG2)or physical fractionation by ultrasound(US).Fractions were characterised by high-performance size exclusion chromatography(HPSEC)and their monosacchari decompositions were determined.Three fractions with high,average and small molar mass,(800,300 and 100103 g/mol respectively),were selected in order to tune the properties of the hydrogel.Sol-gel transition conditions were determined for each fraction by achieving phase diagram using the inverted tube method.Mechanical properties,assessed by rheology,are improved by increasing XG molar mass since elastic modulus is higher for hydrogels formed with higher molar mass fractions as well as the strain at break.Gel formation is likely due to the adsorption of XG fractions on CNC which increases the effective hydrodynamic volume of CNC leading to steric stabilization and interactions between loops and tails of XG adsorbed.展开更多
In order to prepare cellulose nanocrystals( CNCs)-coated polylactide( PLA) microspheres for the use of drug delivery and tissue engineering,a Pickering emulsion route was applied. The stable Pickering emulsions were p...In order to prepare cellulose nanocrystals( CNCs)-coated polylactide( PLA) microspheres for the use of drug delivery and tissue engineering,a Pickering emulsion route was applied. The stable Pickering emulsions were prepared using CNCs as efficient stabilizers without any additional surfactant. The microspheres were successfully fabricated after volatilization of the solvent. What's more,the size of microspheres could be controlled by fabrication parameters.展开更多
文摘This study focuses on the extraction of cellulose nanocrystals (CNC), from microcrystalline cellulose (MCC), derived from Ayous sawdust. The process involves multiple steps and a large amount of chemical products. The objective of this research was to determine the effects of factors that impact the isolation process and to identify the optimal conditions for CNC isolation by using the response surface methodology. The factors that varied during the process were the quantity of MCC, the concentration of sulfuric acid, the hydrolysis time and temperature, and the ultrasonic treatment time. The response measured was the yield. The study found that with 5.80 g of microcrystalline cellulose, a sulfuric acid concentration of 63.50% (w/w), a hydrolysis time of 53 minutes, a hydrolysis temperature of 69˚C, and a sonication time of 19 minutes are the ideal conditions for isolation. The experimental yield achieved was (37.84 ± 0.99) %. The main factors influencing the process were the sulfuric acid concentration, hydrolysis time and temperature, with a significant influence (p < 0.05). Infrared characterization results showed that nanocrystals were indeed isolated. With a crystallinity of 35.23 and 79.74, respectively, for Ayous wood fiber and nanocrystalline cellulose were observed by X-ray diffraction, with the formation of type II cellulose, thermodynamically more stable than native cellulose type I.
基金supported by the Research Foundation Flanders(grant 3E181170)supported by the China Scholarship Council(CSC,201806220066)。
文摘Polypyrrole(PPy)is wildly used as electrode material in supercapacitors due to its high conductivity,low cost,ease of handling,and ease of fabrication.However,limited capacitance and poor cycling stability hinder its practical application.After developing carboxylated cellulose nanocrystals(CNC-COO^(-))as immobile dopants for PPy to improve its cycling stability,we investigated the effect of different commonly used salts(KCl,NaCl,KBr,and NaClO_(4))as dopants during electrode fabrication by electropolymerization.The film’s capacitance increased from 160.6 to 183.4 F g^(-1)after adding a combination of KCl and NaClO_(4) into the electrodeposition electrolyte.More importantly,the porous and interconnected PPy/CNC-COO^(-)-Cl-(Cl O_(4)^(-))_0.5 electrode film exhibited an excellent capacitance of 125.0 F g^(-1)(0.78 F cm^(-2))at a high current density of 2.0 Ag^(-1)(20 m A cm^(-2),allowing charging in less than 1 min),increasing almost 204%over PPy/CNC-COO-films.A symmetric PPy/CNC-COO^(-)-Cl-(ClO_(4)^(-))_0.5 supercapacitor retained its full capacitance after 5000 cycles,and displayed a high energy density of 5.2 Wh kg^(-1)at a power density of 25.4 W kg^(-1)(34.5μWh cm^(-2) at 1752.3μW cm^(-2)).These results reveal that the porous structure formed by doping with CNC-COO-and inorganic salts opens up more active reaction areas to store charges in PPy-based films as the stiff and ribbon-like CNC-COO-as permanent dopants improve the strength and stability of PPy-based films.Our demonstration provides a simple and practical way to deposit PPy based supercapacitors with high capacitance,fast charging,and excellent cycling stability.
基金the China National Postdoctoral Program for Innovative Talents(Bx20200386)China Postdoctoral Science Foundation(2021M703586)+1 种基金Key Program of National Natural Science Foundation of China(52130401)National Natural Science Foundation of China(52204064,52104055)for financial support.
文摘Nanocellulose,a natural polymeric nanomaterial,has attracted significant attention in enhanced oil recovery(EOR)applications due to its abundance,nanoscale,high oil-water interfacial adsorption ef-ficiency.In this study,surface-functionalized cellulose nanocrystals(SF-CNCs)were prepared via hy-drochloric acid hydrolysis and chemical modification,with adaptable nanosize and considerable dispersion stability in low-permeability reservoirs.The SF-CNCs were structurally characterized by FT-IR,Cryo-TEM,which have a diameter of 5-10 nm and a length of 100-200 nm.The SF-CNC dispersions possessed higher stability and stronger salt-tolerance than those of corresponding CNC dispersions,due to the strong hydrophilicity of the sulfonic acid group.It was synergistically used with a non-ionic surfactant(APG1214)to formulate a combined flooding system(0.1 wt%SF-CNC+0.2 wt%APG1214).The combined flooding system exhibits strong emulsification stability,low oil-water interfacial tension of o.03 mN/m,and the ability to alter the wettability for oil-wetting rocks.Furthermore,the combined system was_able to provide an optimum EOR efficiency of 20.2%in low-permeability cores with 30.13×10^(-3)μm^(2).Notably.it can enlarge the sweep volume and increase the displacement efficiency simultaneously.Overall,the newly formulated nanocellulose/surfactant combined system exhibits a remarkable EoR performance in low-permeability reservoirs.
基金National Natural Science Foundation of China(51373131)Fundamental Research Funds for the Central Universities(XDJK2016A017,XDJK2016C033,and WUT-2014-II-009)+1 种基金Project of Basic Science and Advanced Technology Research,Chongqing Science and Technology Commission(cstc2016,jcyjA0796)the Talent Project of Southwest University(SWU115034)
文摘Cellulose nanocrystals(CNCs) have been widely applied in biomaterials and show great biocompatibility and mechanical strength. In this review, the chemical reactions applied in CNC surface modification and their application in CNC based biomaterials are introduced. Furthermore, the conjugation of different functional molecules and nanostructures to the surface of CNCs are discussed, with focus on the binding modes, reaction conditions, and reaction mechanisms. With this introduction, we hope to provide a clear view of the strategies for surface modification of CNCs and their application in biomaterials, thus providing an overall picture of promising CNC-based biomaterials and their production.
文摘As the world's population exponentially grows,so does the need for the production of food,with cereal production growing annually from an estimated 1.0 billion to 2.5 billion tons within the last few decades.This rapid growth in food production results in an ever increasing amount of agricultural wastes,of which already occupies nearly 50%of the total landfill area.For example,is the billions of dry tons of cellulose-containing spent coffee grounds disposed in landfills annually.This paper seeks to provide a method for isolating cellulose nanocrystals(CNCs)from spent coffee grounds,in order to recycle and utilize the cellulosic waste material which would otherwise have no applications.CNCs have already been shown to have vast applications in the polymer engineering field,mainly utilized for their high strength to weight ratio for reinforcement of polymer-based nanocomposites.A successful method of purifying and hydrolyzing the spent coffee grounds in order to isolate usable CNCs was established.The CNCs were then characterized using current techniques to determine important chemical and physical properties.A few crucial properties determined were aspect ratio of 12±3,crystallinity of 74.2%,surface charge density of(48.4±6.2)mM/kg cellulose,and the ability to successfully reinforce a polymer based nanocomposite.These characteristics compare well to other literature data and common commercial sources of CNCs.
文摘In this work,nine different types of edible coating based on pectin,cellulose nanocrystals,glycerol,and essential oil of lemongrass were prepared and used to coat strawberries with a film formed directly on the surface of the coated fruit.The effects of the different edible coatings on refrigerated fruits in terms of weight loss,titratable acidity,total soluble solids,pH,and anthocyanin content was evaluated after 2 days,4 days,6 days,and 8 days of storage.Application of the edible coatings reduced the weight loss of the coated strawberries and the anthocyanin content.The total soluble solids content of or uncoated fruit increase more markedly than that of coated fruit.In contrast,pH was maintained for both coated and uncoated strawberries.The edible coatings were effective in minimizing of the weight loss,without worsening the physical chemistry attributes.The treatments T5 and T9 presented the best results.
文摘Agricultural waste straw is the renewable resource with the highest annual yield in the world.In value-added applications of agricultural waste,dicarboxyl cellulose nanocrystals(DCCs)are prepared from rice,wheat,and corn straw by sequential periodate-chlorite oxidation.In this study,DCCs from rice,wheat,and corn straw were characterized by transmission electron microscopy(TEM),Fourier transform infrared spectrometer,X-ray diffractometer(XRD),and thermal gravimetric analysis(TGA).The carboxyl content of the DCCs was also investigated.XRD results show that the crystallinity index decreased after sequential periodate-chlorite oxidation;however,the cellulose I structure was maintained.TEM results show that rod-shaped DCCs with an average length and width of 287.0 nm and 9.9 nm,respectively,were successfully prepared by sequential periodate-chlorite oxidation.The carboxyl content of the DCCs was around 3.9 mmol/g,and not affected by the type of straw.Experiments to study the removal of copper ions in aqueous medium were performed with the prepared DCCs.The adsorption capacities of copper ions were 131,162,and 144 mg/g for DCCs prepared from rice,wheat,and corn straws,respectively.The results show that DCCs prepared from rice,wheat,and corn straws by sequential periodatechlorite oxidation have potential for the removal of copper ions from aqueous medium.
基金The authors are grateful for the financial support from NNSF China(grant nos.21975095,21671079,and 21373100)111 project(grant no.B17020),JLU international co-advisorship program(grant no.419020201362)+1 种基金JLU international collaboration program(grant no.45119031C015)the State key laboratory of inorganic synthesis and preparative chemistry of JLU(grant no.1G3194101461).
文摘Chiroptical materials are widely used in photonic devices,enantioselective catalysis and bio-sensors.Cellulose-base chiroptical materials with multilength scale structural hierarchy and unique light manipulation ability found in nature provide inspiration for materials design.Cellulose nanocrystals(CNC)display twisted rod morphology and hierarchical chirality.Leveraging the evaporation-induced self-assembly of negatively charged CNC,a broad realm of CNC-based chiroptical materials featuring one-dimensional photonic bandgap and novel chiroptical properties have been developed,which are of scientific and technological significance.Here we presented a brief overview on CNC-based chiroptical materials by evaporation-induced self-assembly,showed energy and chirality transfer in a host-guest environment leading to photonic bandgap modulation of optoelectronic properties,outlined novel chiroptical phenomena and their underlying principles,and demonstrated the application potentials of the CNC-based chiroptical materials.
基金supported by the National Key Research and Development Program of China(2019YFE0106900)。
文摘With excellent biocompatibility and unique physiochemical properties,nanocelluloses including cellulose nanocrystals(CNCs)and cellulose nanofibrils(CNFs)are promising candidates for preparing biomedical hydrogels.CNCs and CNFs are different in morphology and surface charges.Herein,CNCs and two CNFs(CNFs-C,Carboxylated CNFs;CNFs-P,Phosphorylated CNFs)were synthesized and applied to fabricate hydrogels through metal crosslinking.Aluminum crosslinking was found to be the best choice for enhancing the strength.This study systematically compared the morphologies,storage modulus,loss factor,continuous shear ramp,self-healing,swelling,in vitro degradation and injectable properties of the fabricated hydrogels,Further,a radar chart is summarized as guidelines to direct the rational selection to meet the specific requirements of further biomedical applications.At the same nanocellulose concentration and after Al^(3+)crosslinking,CNCs hydrogels had strong water holding capacity twice as much as that of CNFs hydrogels.While CNFs hydrogels showed higher hardness and stronger resistance to degradation than that of CNCs.These results provide detailed insights into nanocellulose hydrogels,making it possible to use these guidelines to select hydrogels for desired performance.
基金supported by the Research Foundation Flanders,Belgium(3E181170 and 12Y0319N)supported by the China Scholarship Council,China(CSC,201806220066)。
文摘Porous three-dimensional (3D) structures generally improve the performance of electrodes by increasing their active surface area and the diffusion speed of electrolyte ions during charging/discharging.Threedimensional polypyrrole (PPy) based films were created by electrodepositing PPy in the presence of varying amounts of chloride anions (Cl^(-)) and polyanionic ribbonlike nanoparticles (carboxylated cellulose nanocrystals (CNC-COO-)) as scaffold material.The assembly mechanism of the 3D PPy electrodes combines the effect of different nucleation and growth mechanisms during electropolymerization and deposition of the formed PPy with CNC-COO-and with Cl^(-).The highest area capacitance of these electrode materials was 1.39 F cm^(-2)(150.2 F g^(-1)) at a current density of 1 m A cm^(-2)(0.1 A g^(-1)).More importantly,at a high current density of 20 m A cm^(-2)(2.2 A g^(-1)),the thick (ca.130μm),3D,and high mass loading(9.2 mg cm^(-2)) Cl^(-):CNC-COO-/PPy films exhibited an excellent areal capacitance of 0.85 F cm^(-2)(70.8 F g^(-1)),increasing about 16%over CNC-COO-/PPy films prepared without Cl^(-)present during electrodeposition.In addition,an aqueous Cl^(-):CNC-COO-/PPy (with Cl^(-):CNC-COO-=2.0) symmetric supercapacitor had an outstanding energy density of 41.15μWh cm^(-2)(4.46 Wh kg^(-1)) and excellent cycling stability,while even improving on its original areal capacitance (to 111.2%of its original capacitance) after cycling3000 cycles at 8 m A cm^(-2),indicating their potential in energy storage devices.
文摘The aim of this work was to use cellulose nanocrystals that were obtained by hydrolysis in phosphoric acid solution and further modified with succinic anhydride in the microwave field for PLA reinforcement.A series of allbionanocomposites containing unmodified and surface modified cellulose nanocrystals with CNC content in the range of 1–3%_(w.t.) were obtained by melt blending and tested by XRD,SEM,DSC and DMA to investigate the effect of surface esterification of CNCs on the structure,morphology,dynamic mechanical properties of bionanocomposites,as well as phase transitions of PLA in the presence of cellulosic nanofiller.DMA investigations showed the highest increase of storage modulus by ca.7%(335 MPa at 25℃)in the glassy state of PLA for 2%_(w.t.)of unmodified CNC.Though,addition of 2%_(w.t.)of succinylated CNCs caused the highest increase of the onset of glass transition temperature(by 6.2℃)thus widening the temperature range of biocomposite application.The increase of glass transition temperature indicates the strongest interfacial interactions due to improved miscibility of surface modified nanocrystals and thus good dispersion of additive in PLA matrix providing high interface.
基金financially supported by the Natural Sciences and Engineering Research Council of Canada(No.RGPIN-2017-05537)the Alberta Innovates CNC Challenge 3.0 Grant(No.BFC 18009)。
文摘Acid mine drainage presents an important threat to cementitious structures.This study is aimed at investigating the effect of cellulose nanocrystals(CNCs)on the acid resistance of cementitious composites.CNCs were added to mortar mixtures as additives at cement volume ratios of 0.2vol%,0.4vol%,1.0vol%,and 1.5vol%.After 28 d of standard curing,the samples were immersed in a sulfuric acid with a pH value of 2 for 75 d.The unconfined compressive strength(UCS)test,the density,water absorption,void volume test,and thermogravimetric analysis were carried out to investigate the properties of CNC mixtures before sulfuric acid immersion.It was found that the addition of CNC reduced the volume of permeable voids and increased the hydration degree and mechanical strength of the samples.Changes in mass and length were monitored during immersion to evaluate the acid resistance of mixtures.The mixture with 0.4vol%CNC showed a reduced mass change and length change indicating its improved acid resistance.
文摘Rheometer and differential scanning calorimetry (DSC) have been used to probe the mechanism of gelation in gels formed by mixture of k-carrageenan and cellulose nanocrystals (CNC). The results indicated that an association occurred between CNC chains and aggregated k-carrageenan helices.
文摘Although nanocomposites have recently attracted special interest in the tissue engineering area,due to their potential to reinforce scaffolds for hard tissues applications,a number of variables must be set prior to any clinical application.This manuscript addresses the evaluation of thermo-mechanical properties and of cell proliferation of cellulose nanocrystals(CNC),poly(butylene adipate-co-terephthalate)(PBAT),poly(ε-caprolactone)(PCL)films and their bionanocomposites with 2 wt% of CNC obtained by casting technique.Cellulose nanocrystals extracted from Balsa wood by acid hydrolysis were used as a reinforcing phase in PBAT and PCL matrix films.The films and pure CNC at different concentrations were cultured with osteoblasts MG-63 and the cell proliferation was assessed by AlamarBlue?assay.The thermal-mechanical properties of the films were evaluated by dynamic-mechanical thermal analysis(DMTA).It was found by DMTA that the CNC acted as reinforcing agent.The addition of CNCs in the PBAT and PCL matrices induced higher storage moduli due to the reinforcement effects of CNCs.The cell viability results showed that neat CNC favored osteoblast proliferation and both PBAT and PCL films incorporated with CNC were biocompatible and supported cell proliferation along time.The nature of the polymeric matrix or the presence of CNC practically did not affect the cell proliferation,confirming they have no in vitro toxicity.Such features make cellulose nanocrystals a suitable candidate for the reinforcement of biodegradable scaffolds for tissue engineering and biomedical applications.
基金funded by the Russian Ministry of Education and Science(state contract no.14.W03.31.0014,MegaGrant).
文摘The biocomposite films were prepared from poly(L-lactic acid)and cellulose nanocrystals.To improve interfacial compatibility of hydrophilic cellulose nanocrystals with hydrophobic matrix polymer as well as to provide the osteoconductive properties,cellulose was functionalized with poly(glutamic acid).The modified cellulose nanocrystals were better distributed and less aggregated within the matrix,which was testified by scanning electron,optical and polarized light microscopy.According to mechanical tests,composites filled with nanocrystals modified with PGlu demonstrated higher values of Young’s modulus,elongation at break and tensile strength.Incubation of composite materials in model buffer solutions for 30 weeks followed with staining of Ca^(2+)deposits with Alizarin Red S assay testified better mineralization of materials containing PGlu-modified cellulose nanocrystals as filler.As the result of in vivo experiment,the developed composite materials showed less level of inflammation in comparison with pure polymer matrix and composites filled with non-functionalized cellulose nanocrystals.
基金French National Research Agency(Project Cellmach,ANR-17-CE07-0010-01)Region Pays de la Loire(Project Nanomach,Etoiles Montantes 2017-10691).
文摘In this work,we studied the adsorption of modified cellulose nanocrystals onto solid surfaces by quartz crystal microbalance with dissipation monitoring(QCM-D).Cellulose nanocrystals obtained from tunicate(CNC)were modified at reducing end by amidation reactions.Two different functionalities were investigated:a polyamine dendrimer(CNC-NH_(2)),which interacts with gold surface by the amine groups;and a biotin moiety(CNC-Biot),which has a strong affinity for the protein streptavidin(SAV).QCM-D results revealed different adsorption behaviors between modified and unmodified CNCs.Hence,unmodified CNCs covered almost all the surface forming a rigid and flat layer whereas reducing end modified CNCs remained rather upright forming a hydrated and viscoelastic layer with lower surface coverage.The analysis of adsorption kinetics allowed the calculation of an apparent collision rate factor,which resulted 10-fold higher for unmodified CNCs compared to reducing end modified CNCs,therefore,demonstrating the different adsorption behavior.
基金This work is funded by Researchers Supporting Project number(RSP-2021/117)King Saud University,Riyadh,Saudi Arabia.The authors would like to thank the“PHC Utique”program of the French Ministry of Foreign Affairs and Ministry of Higher Education and Researchthe Tunisian Ministry of Higher Education and Scientific Research in the CMCU Project No.18G1132 for the financial support.
文摘Cellulose nanocrystal(CNC)is a biomaterial derived from plant lignocellulosic components,widely applied in various industrial fields.Concurrently,with the growth of awareness in developing green nanomaterial,the explored Washingtonia fibre could be alternative biomass for obtaining CNC products.In the present work,different acid concentrations of 5%,15%,and 25%hydrochloric solutions were employed to produce CNCs from Washingtonia fibre.With the chemical treatments,the yield of the CNC product was successfully retained at 21.6%-25.1%.Individually separated and needle-shaped CNC particles could be observed under the microscopic viewing with the increased acid concentrations.From elemental analysis,a relatively pure cellulose compartment was produced for all CNC samples.The zeta potential values between-10 to-16 mV proved that each nanoparticle sample possessed dispersion ability within an aqueous solution.Meanwhile,the degree of crystallinity and the thermal behavior of CNCs were enhanced with the increased acidic concentrations.Hence,the isolated CNCs(with 15%)from Washingtonia fibre lead a CNC with the highest aspect ratio(30).This parameter is so important that these structures show empowering points of view as nanomaterials for reinforced polymer composites,and it could be a reliable nano-filler for the composite fabrication process in the future.
基金by the Basic Sientific Research Funds of International Center for Bamboo and Rattan(1632018016)the Special Scientific Research Fund of Construction of High-level teachers Project of Beijing Institute of Fashion Technology(BIFTQG201805)+1 种基金“Nan Taihu Lake elite plan”project([2018]No.2,Huzhou city,Zhejiang province)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX17-0828).
文摘The cellulose nanocrystals/graphene composite aerogel(CGA)and polyvinyl alcohol/cellulose nanocrystals/graphene composite aerogel(PCGA)were prepared by suspension titration,tert-butanol solution replacement and freeze-drying successively.The removal rates of methyl blue(MB)from water by CGA and PCGA were evaluated and the effects of additions,adsorption time,reaction temperature and pH value of CGA and PCGA on MB removal rate were discussed.It was found that the optimal concentrations of both CGA and PCGA were 2 g∙L-1 in the adsorption reaction process and the adsorption equilibrium was reached within 120 min.The higher the initial pH value of MB solution is,the better the removal effect will be.The adsorption kinetics conformed to the pseudo-second-order kinetic model.The langmuir isothermal adsorption equation showed the maximum adsorption capacities of CGA and PCGA were 125 mg∙g-1 and 110.9 mg∙g-1,respectively.Under the conditions of adsorption time of 120 min,reaction temperature of 323 K,and initial MB solution pH value of 11,both CGA and PCGA had higher removal rates of MB,reaching more than 98%.
文摘Plant components are an inexhaustible source for the construction of bio-based materials.Here we report,for the first time,the elaboration of biobased cellulose nanocrystals(CNC)/xyloglucan(XG)hydrogels.XG is a hemicellulose displaying a great affinity for cellulose surface and can be thus irreversibly adsorbed on CNC.Properties of the hydrogels were investigated by varying the molar mass of XG either by enzymatic treatment with Endo-glucanase(EG2)or physical fractionation by ultrasound(US).Fractions were characterised by high-performance size exclusion chromatography(HPSEC)and their monosacchari decompositions were determined.Three fractions with high,average and small molar mass,(800,300 and 100103 g/mol respectively),were selected in order to tune the properties of the hydrogel.Sol-gel transition conditions were determined for each fraction by achieving phase diagram using the inverted tube method.Mechanical properties,assessed by rheology,are improved by increasing XG molar mass since elastic modulus is higher for hydrogels formed with higher molar mass fractions as well as the strain at break.Gel formation is likely due to the adsorption of XG fractions on CNC which increases the effective hydrodynamic volume of CNC leading to steric stabilization and interactions between loops and tails of XG adsorbed.
基金National Key Technology R&D Program of China(No.2014BAC13B02)National Natural Science Foundation of China(No.51403035)+1 种基金Programme of Introducing Talents of Discipline to Universities,China(No.105-07-005735)the Fundamental Research Funds for the Central Universities,China(No.15D110510)
文摘In order to prepare cellulose nanocrystals( CNCs)-coated polylactide( PLA) microspheres for the use of drug delivery and tissue engineering,a Pickering emulsion route was applied. The stable Pickering emulsions were prepared using CNCs as efficient stabilizers without any additional surfactant. The microspheres were successfully fabricated after volatilization of the solvent. What's more,the size of microspheres could be controlled by fabrication parameters.