As the rapid development of portable and wearable devices,different electromagnetic interference(EMI)shielding materials with high efficiency have been desired to eliminate the resulting radiation pollution.However,li...As the rapid development of portable and wearable devices,different electromagnetic interference(EMI)shielding materials with high efficiency have been desired to eliminate the resulting radiation pollution.However,limited EMI shielding materials are successfully used in practical applications,due to the heavy thickness and absence of sufficient strength or flexibility.Herein,an ultrathin and flexible carbon nanotubes/MXene/cellulose nanofibrils composite paper with gradient and sandwich structure is constructed for EMI shielding application via a facile alternating vacuum-assisted filtration process.The composite paper exhibits outstanding mechanical properties with a tensile strength of 97.9±5.0 MPa and a fracture strain of 4.6±0.2%.Particularly,the paper shows a high electrical conductivity of 2506.6 S m?1 and EMI shielding effectiveness(EMI SE)of 38.4 dB due to the sandwich structure in improving EMI SE,and the gradient structure on regulating the contributions from reflection and absorption.This strategy is of great significance in fabricating ultrathin and flexible composite paper for highly efficient EMI shielding performance and in broadening the practical applications of MXene-based composite materials.展开更多
To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-co...To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.展开更多
Bleached bamboo kraft pulp was pretreated by 2,2,6,6-tetramethylpiperidine-l-oxy radical （TEMPO）- mediated oxidation using a TEMPO/NaBr/NaC10 system at pH = 10 in water to facilitate mechanical disintegration into T...Bleached bamboo kraft pulp was pretreated by 2,2,6,6-tetramethylpiperidine-l-oxy radical （TEMPO）- mediated oxidation using a TEMPO/NaBr/NaC10 system at pH = 10 in water to facilitate mechanical disintegration into TEMPO-oxidized cellulose nanofibrils （TO-CNs）. A series of TO-CNs with different carboxylate contents were obtained by varying amounts of added NaC10. An increase in carboxylate contents results in aqueous TO-CN dispersions with higher yield, zeta potential values, and optical transparency. When carboxylate groups are introduced, the DPv value of the TO-CNs remarkably decreases and then levels off. And the presence of hemicellulose in the pulp is favorable to TEMPO oxidization. After the oxidization, the native cellulose I crystalline structure and crystal size of bamboo pulp are almost maintained. TEM micrographs revealed that the degree of nanofibrillation is directly proportional to the carboxylate contents. With increasing carboxylate con- tents, the free-standing TO-CN films becomes more transparent and mechanically stronger. The oxygen permeability of PLA films drastically decreases from 355 for neat PLA to 8.4 mL-1 m a. d-1 after coating a thin layer of TO-CN with a carboxylate content of 1.8 mmol.g1. Therefore, inexpensive and abundant bamboo pulp would be a promising starting material to isolate cellulose nanfibrils for oxygen-barrier applications.展开更多
This paper introduces a concentrated di-carboxylic acid(DCA) hydrolysis process for the integrated production of thermally stable and carboxylated cellulose nanocrystals(CNCs) and cellulose nanofibrils(CNFs). The DCA ...This paper introduces a concentrated di-carboxylic acid(DCA) hydrolysis process for the integrated production of thermally stable and carboxylated cellulose nanocrystals(CNCs) and cellulose nanofibrils(CNFs). The DCA hydrolysis process addressed several issues associated with mineral acid hydrolysis for CNC production, such as cellulose loss and acid recovery. The surface and morphological properties of the cellulose nanomaterials resulting from the DCA hydrolysis process can be tailored simply by controlling the severity of DCA hydrolysis. To further reduce cost, a lowtemperature(≤80℃) hydrotropic chemical process using p-toluenesulfonic acid(p-Ts OH) was also introduced to rapidly fractionate raw lignocelluloses for the production of lignin containing cellulose nanofibrils(LCNFs) and lignin nanoparticles(LNPs). The LCNF surface hydrophobicity and morphology can be tailored by controlling the fractionation severity, i.e., the extent of delignification. The lignin also improved the thermal stability of LCNFs. LNPs can be easily separated by diluting the spent acid liquor to below the p-Ts OH minimal hydrotropic concentration of approximately 10%. p-Ts OH can also be easily recovered by re-concentrating the diluted spent liquor after lignin precipitation. We believe that these two novel processes presented here have the potential to achieve true sustainable, economic, and tailored production of cellulose nanomaterials, suitable for a variety of applications.展开更多
In this study, cellulose nanocrystals(CNC) with surface carboxylic groups were prepared from bleached softwood pulp by hydrolysis with concentrated citric acid at concentrations of 60 wt%~80 wt%. The solid residues fr...In this study, cellulose nanocrystals(CNC) with surface carboxylic groups were prepared from bleached softwood pulp by hydrolysis with concentrated citric acid at concentrations of 60 wt%~80 wt%. The solid residues from acid hydrolysis were collected for producing cellulose nanofibrils(CNF) via post high-pressure homogenization. Citric acid could be easily recovered after hydrolysis reactions through crystallization due to its low water solubility or through precipitation as a calcium salt followed by acidification. Several important properties of CNC and CNF, such as dimension, crystallinity, surface chemistry, thermal stability, were evaluated. Results showed that the obtained CNC and CNF surfaces contained carboxylic acid groups that facilitated functionalization and dispersion in aqueous processing. The recyclability of citric acid and the carboxylated CNC/CNF give the renewable cellulose nanomaterial huge potential for a wide range of industrial applications. Furthermore, the resultant CNC and CNF were used as reinforcing agents to make sodium carboxymethyl cellulose(CMC) films. Both CNC and CNF showed reinforcing effects in CMC composite films. The tensile strength of CMC films increased by 54.3% and 85.7% with 10 wt% inclusion of CNC and CNF, respectively. This study provides detailed information on carboxylated nanocellulose prepared by critic acid hydrolysis; a sustainable approach for the preparation of CNC/CNF is of significant importance for their various uses.展开更多
Solid-state lithium(Li) metal batteries overwhelm the lithium-ion batteries by harvesting high energy from Li metal anode with ultrahigh capacities and gaining excellent safety from solid electrolytes.However,the unco...Solid-state lithium(Li) metal batteries overwhelm the lithium-ion batteries by harvesting high energy from Li metal anode with ultrahigh capacities and gaining excellent safety from solid electrolytes.However,the uncontrollable solvents in solid electrolytes usually aggravate poor interfacial contact with lithium metal anode and deteriorate Li^(+) pathways.Here a copolymeric network-structured ion conductor by rationally integrating cellulose nanofibril as a two-in-one functional material is employed to anchor the solvent.Taking advantages of tightly anchoring of cellulose nanofibril to solvent,the asconstructed quasi-solid polymer-based electrolyte offers rapid Li^(+) transport channels and realizes effective Li-dendrite suppression,which enables high ionic conductivity of 1.93 × 10^(-3)S cm^(-1) at room temperature,long-term Li plating/stripping over 1900 h,and high capacity retention of 99%.This work provides a fresh strategy for creating solid electrolytes that meet both high ionic conductivity and interfacial stability requirements for practical solid-state lithium metal battery.展开更多
TiO2 nanofibrils were prepared within the pores of alumina template membrane by use of sol-gel chemistry. The TiO2 nanofibrils have good crystallinity and size. There is agglomeration free among the particulates of ...TiO2 nanofibrils were prepared within the pores of alumina template membrane by use of sol-gel chemistry. The TiO2 nanofibrils have good crystallinity and size. There is agglomeration free among the particulates of TiO2 and the fibrils show high catalytic activity.展开更多
We review the recent progress that have led to the development of porous materials based on cellulose nanostructures found in plants and other resources. In light of the properties that emerge from the chemistry, shap...We review the recent progress that have led to the development of porous materials based on cellulose nanostructures found in plants and other resources. In light of the properties that emerge from the chemistry, shape and structural control, we discuss some of the most promising uses of a plant-based material, nanocellulose, in regenerative medicine. Following a brief discussion about the fundamental aspects of self-assembly of nanocellulose precursors, we review the key strategies needed for material synthesis and to adjust the architecture of the materials (using three-dimensional printing, freeze-casted porous materials, and electrospinning) according to their uses in tissue engineering, artificial organs, controlled drug delivery and wound healing systems, among others. For this purpose, we map the structure-property-function relationships of nanocellulose-based porous materials and examine the course of actions that are required to translate innovation from the laboratory to industry. Such efforts require attention to regulatory aspects and market pull. Finally, the key challenges and opportunities in this nascent field are critically reviewed.展开更多
Amyloid nanofibrils(ANFs)are supramolecular polymers originally classified as pathological markers in various human degenerative diseases.However,in recent years,ANFs have garnered greater interest and are regarded as...Amyloid nanofibrils(ANFs)are supramolecular polymers originally classified as pathological markers in various human degenerative diseases.However,in recent years,ANFs have garnered greater interest and are regarded as nature-based sustainable biomaterials in environmental science,material engineering,and nanotechnology.On a laboratory scale,ANFs can be produced from food proteins via protein unfolding,misfolding,and hydrolysis.Furthermore,ANFs have specific structural characteristics such as a high aspect ratio,good rigidity,chemical stability,and a controllable sequence.These properties make them a promising functional material in water decontamination research.As a result,the fabrication and application of ANFs and their composites in water purification have recently gained considerable attention.Despite the large amount of literature in this field,there is a lack of systematic review to assess the gap in using ANFs and their composites to remove contaminants from water.This review discusses significant advancements in design techniques as well as the physicochemical properties of ANFs-based composites.We also emphasize the current progress in using ANFs-based composites to remove inorganic,organic,and biological contaminants.The interaction mechanisms between ANFs-based composites and contaminants are also highlighted.Finally,we illustrate the challenges and opportunities associated with the future preparation and application of ANFs-based composites.We anticipate that this review will shed new light on the future design and use of ANFs-based composites.展开更多
Cellulose nanopaper has shown great potential in diverse fields including optoelectronic devices,food packaging,biomedical application,and so forth,owing to their various advantages such as good flexibility,tunable li...Cellulose nanopaper has shown great potential in diverse fields including optoelectronic devices,food packaging,biomedical application,and so forth,owing to their various advantages such as good flexibility,tunable light transmittance,high thermal stability,low thermal expansion coefficient,and superior mechanical properties.Herein,recent progress on the fabrication and applications of cellulose nanopaper is summarized and discussed based on the analyses of the latest studies.We begin with a brief introduction of the three types of nanocellulose:cellulose nanocrystals,cellulose nanofibrils and bacterial cellulose,recapitulating their differences in preparation and properties.Then,the main preparation methods of cellulose nanopaper including filtration method and casting method as well as the newly developed technology are systematically elaborated and compared.Furthermore,the advanced applications of cellulose nanopaper including energy storage,electronic devices,water treatment,and high-performance packaging materials were highlighted.Finally,the prospects and ongoing challenges of cellulose nanopaper were summarized.展开更多
Nanoparticles in air are of particular concern for public health and employee exposure in work-places. Therefore, it is very important to prepare effective filters for their removal. In this work filters were prepared...Nanoparticles in air are of particular concern for public health and employee exposure in work-places. Therefore, it is very important to prepare effective filters for their removal. In this work filters were prepared from nanocellulose, i.e. cellulose nanofibrils (CNF). CNF was produced using two methods giving two different qualities of CNF. One quality had negative charges on the fibril surfaces while the other was neutral, and had in addition thinner fibrils compared to the other qualities. Filter samples were produced from water dispersions of CNF, by removal of the water by freeze drying. The performance of the CNF based filters was assessed and compared with filters based on synthetic polymer fibres. The ability to collect NaCl particles with a broad size distribution, ranging from nanometer to micrometer scale, was determined. CNF filters showed quality values comparable with the synthetic polymer based filters. Filters based on both the two CNF qualities had very good filtration efficiency for a given pressure drop across the filter.展开更多
Fiber morphology with off-standing branches,as found in nature,e.g.,in goose downy feather,provides exquisite functions that can be barely achieved by man-made fiber systems.In this work,we develop a simple and scalab...Fiber morphology with off-standing branches,as found in nature,e.g.,in goose downy feather,provides exquisite functions that can be barely achieved by man-made fiber systems.In this work,we develop a simple and scalable method for generating downy feather-like para-aramid fibers and assemblies.Through treating commercial para-aramid microfibers with mild alkaline solution(low concentration of NaOH),a synergistic effect of chemical hydrolysis and physical shearing is successfully triggered to generate abundant nanofiber branches on the surface of para-aramid fibers.When compared with conventional monotonous structures,nonwovens composed of downy feather-like fibers exhibit a typical multiscale fiber morphology,larger specific surface area and smaller pore size,thus showing enhanced particles adsorption capacity(over twice of the pristine nonwoven),excellent oil absorption capacity(increased by~50%),improved air filtration performances(doubled the filtration efficiency)and effective thermal insulation(thermal conductivity=26.1 mW·m^(−1)·K^(−1)).More attractively,the intrinsic flame-retardant nature of para-aramid is well inherited by the downy feather-like fibers,and the fabrication process requires neither sophisticated equipment,nor tedious procedures,making us believe the strong competitiveness of these fibers and assemblies.展开更多
A tremendous amount of wheat straw(WS)has been generated by wheat crops every year,while only a small percentage is being used in applications,and most get burned on the field,causing a large amount of the exhaust gas...A tremendous amount of wheat straw(WS)has been generated by wheat crops every year,while only a small percentage is being used in applications,and most get burned on the field,causing a large amount of the exhaust gas that pollutes the environment.Herein,we report on the extraction of cellulose nanofibrils(CNF)from the alkali treated WS by a combination of 2,2,6,6-tetramethylpyperidine-1-oxyl(TEMPO)-oxidation and mechanical disintegration method.The crystalline structures,thermal properties,natural charge of the CNF were examined.The re-sultant nano-building blocks of the CNF was assembled into macroscopic cellulose materials,i.e.,film,aerogel,and filament in this work.Furthermore,the morphologies and microstructues as well as other properties of these three kinds of the CNF assemblies were investigated.The ob-tained CNF and its assemblies showed a potential application in new materials areas.This work explored a new way to utilize the discarded WS instead of being burned.展开更多
Waste material from the fishing industry disposed off-shore exceeds 250 billion tons/year, and it is considered hazardous due to its high perishability and polluting effect, both on land and sea. Considering the actua...Waste material from the fishing industry disposed off-shore exceeds 250 billion tons/year, and it is considered hazardous due to its high perishability and polluting effect, both on land and sea. Considering the actual production of chitin, chitosan and oligosaccharides from crustaceons, it is understandable how difficult it is to eliminate all the waste material obtained from food industry, therefore the need for more innovation and creativity. With this in mind we propose an industrial use of the natural chitin nanocrystals (known as chitin-nanofibrils-CN) to produce innovative cosmetics, food supplements and protective films that can improve our way of living while saving the environment.展开更多
基金financial support from the National Natural Science Foundation of China(31771081,51472259)the Science and Technology Commission of Shanghai Municipality(18ZR1445100)Beijing Forestry University Outstanding Young Talent Cultivation Project(2019JQ03014).
文摘As the rapid development of portable and wearable devices,different electromagnetic interference(EMI)shielding materials with high efficiency have been desired to eliminate the resulting radiation pollution.However,limited EMI shielding materials are successfully used in practical applications,due to the heavy thickness and absence of sufficient strength or flexibility.Herein,an ultrathin and flexible carbon nanotubes/MXene/cellulose nanofibrils composite paper with gradient and sandwich structure is constructed for EMI shielding application via a facile alternating vacuum-assisted filtration process.The composite paper exhibits outstanding mechanical properties with a tensile strength of 97.9±5.0 MPa and a fracture strain of 4.6±0.2%.Particularly,the paper shows a high electrical conductivity of 2506.6 S m?1 and EMI shielding effectiveness(EMI SE)of 38.4 dB due to the sandwich structure in improving EMI SE,and the gradient structure on regulating the contributions from reflection and absorption.This strategy is of great significance in fabricating ultrathin and flexible composite paper for highly efficient EMI shielding performance and in broadening the practical applications of MXene-based composite materials.
文摘To improve the performance of polyurethane films,small amounts of cellulose nanofibrils(CNF)were physically blended with a waterborne polyurethane(WPU)emulsion,and then CNF/WPU composite films were prepared by cast-coating and drying.The particle size of the emulsions and the chemical structure,micromorphology,thermal stability,mechanical properties,and water resistance of the composite films were characterized using a Malvern laser particle size analyzer,Fourier transform infrared spectroscopy(FT-IR),scanning electron microscopy(SEM),thermogravimetric analysis(TGA),an electronic strength machine,water contact angle analysis(WCA),and water absorption tests,respectively.The results showed that at a low CNF content of 0.3 wt%,the particle size of the WPU emulsion and chemical structure of the film did not change significantly.In addition,the tensile strength of the composite film increased by up to 108%compared to the neat WPU film,and the thermal stability and water resistance were slightly improved.The addition of CNF greatly enhanced the tensile strength while maintaining the other original properties of the WPU film,which may greatly improve the service life and tear resistance of commercial coatings in the future.
文摘Bleached bamboo kraft pulp was pretreated by 2,2,6,6-tetramethylpiperidine-l-oxy radical （TEMPO）- mediated oxidation using a TEMPO/NaBr/NaC10 system at pH = 10 in water to facilitate mechanical disintegration into TEMPO-oxidized cellulose nanofibrils （TO-CNs）. A series of TO-CNs with different carboxylate contents were obtained by varying amounts of added NaC10. An increase in carboxylate contents results in aqueous TO-CN dispersions with higher yield, zeta potential values, and optical transparency. When carboxylate groups are introduced, the DPv value of the TO-CNs remarkably decreases and then levels off. And the presence of hemicellulose in the pulp is favorable to TEMPO oxidization. After the oxidization, the native cellulose I crystalline structure and crystal size of bamboo pulp are almost maintained. TEM micrographs revealed that the degree of nanofibrillation is directly proportional to the carboxylate contents. With increasing carboxylate con- tents, the free-standing TO-CN films becomes more transparent and mechanically stronger. The oxygen permeability of PLA films drastically decreases from 355 for neat PLA to 8.4 mL-1 m a. d-1 after coating a thin layer of TO-CN with a carboxylate content of 1.8 mmol.g1. Therefore, inexpensive and abundant bamboo pulp would be a promising starting material to isolate cellulose nanfibrils for oxygen-barrier applications.
基金financial support from the US Forest Servicethe National Natural Science Foundation of China(Project No.31470599)the Doctorate Fellowship Foundation of Nanjing Forestry University
文摘This paper introduces a concentrated di-carboxylic acid(DCA) hydrolysis process for the integrated production of thermally stable and carboxylated cellulose nanocrystals(CNCs) and cellulose nanofibrils(CNFs). The DCA hydrolysis process addressed several issues associated with mineral acid hydrolysis for CNC production, such as cellulose loss and acid recovery. The surface and morphological properties of the cellulose nanomaterials resulting from the DCA hydrolysis process can be tailored simply by controlling the severity of DCA hydrolysis. To further reduce cost, a lowtemperature(≤80℃) hydrotropic chemical process using p-toluenesulfonic acid(p-Ts OH) was also introduced to rapidly fractionate raw lignocelluloses for the production of lignin containing cellulose nanofibrils(LCNFs) and lignin nanoparticles(LNPs). The LCNF surface hydrophobicity and morphology can be tailored by controlling the fractionation severity, i.e., the extent of delignification. The lignin also improved the thermal stability of LCNFs. LNPs can be easily separated by diluting the spent acid liquor to below the p-Ts OH minimal hydrotropic concentration of approximately 10%. p-Ts OH can also be easily recovered by re-concentrating the diluted spent liquor after lignin precipitation. We believe that these two novel processes presented here have the potential to achieve true sustainable, economic, and tailored production of cellulose nanomaterials, suitable for a variety of applications.
基金financial support for this work is from the National Science&Technology Pillar Program during the Twelfth Five-year Plan Period(No.2015BAD14B06)the National Natural Science Foundation of China(No.31470609,No.25106240 and No.21433001)+1 种基金the Primary Research and Development Plan of Shandong Province(No.2016GGX104003 and No.2016CYJS07A02)the Young Taishan Scholars Program of Shandong Province(No.tsqn20161052)
文摘In this study, cellulose nanocrystals(CNC) with surface carboxylic groups were prepared from bleached softwood pulp by hydrolysis with concentrated citric acid at concentrations of 60 wt%~80 wt%. The solid residues from acid hydrolysis were collected for producing cellulose nanofibrils(CNF) via post high-pressure homogenization. Citric acid could be easily recovered after hydrolysis reactions through crystallization due to its low water solubility or through precipitation as a calcium salt followed by acidification. Several important properties of CNC and CNF, such as dimension, crystallinity, surface chemistry, thermal stability, were evaluated. Results showed that the obtained CNC and CNF surfaces contained carboxylic acid groups that facilitated functionalization and dispersion in aqueous processing. The recyclability of citric acid and the carboxylated CNC/CNF give the renewable cellulose nanomaterial huge potential for a wide range of industrial applications. Furthermore, the resultant CNC and CNF were used as reinforcing agents to make sodium carboxymethyl cellulose(CMC) films. Both CNC and CNF showed reinforcing effects in CMC composite films. The tensile strength of CMC films increased by 54.3% and 85.7% with 10 wt% inclusion of CNC and CNF, respectively. This study provides detailed information on carboxylated nanocellulose prepared by critic acid hydrolysis; a sustainable approach for the preparation of CNC/CNF is of significant importance for their various uses.
基金financial support from the projects of the National Natural Science Foundation of China (52373074 and 51972121)the Independent Research Project of Maoming Laboratory (2022ZD002)。
文摘Solid-state lithium(Li) metal batteries overwhelm the lithium-ion batteries by harvesting high energy from Li metal anode with ultrahigh capacities and gaining excellent safety from solid electrolytes.However,the uncontrollable solvents in solid electrolytes usually aggravate poor interfacial contact with lithium metal anode and deteriorate Li^(+) pathways.Here a copolymeric network-structured ion conductor by rationally integrating cellulose nanofibril as a two-in-one functional material is employed to anchor the solvent.Taking advantages of tightly anchoring of cellulose nanofibril to solvent,the asconstructed quasi-solid polymer-based electrolyte offers rapid Li^(+) transport channels and realizes effective Li-dendrite suppression,which enables high ionic conductivity of 1.93 × 10^(-3)S cm^(-1) at room temperature,long-term Li plating/stripping over 1900 h,and high capacity retention of 99%.This work provides a fresh strategy for creating solid electrolytes that meet both high ionic conductivity and interfacial stability requirements for practical solid-state lithium metal battery.
基金supported by the National Natural Science Foundation of China(No 69890220)
文摘TiO2 nanofibrils were prepared within the pores of alumina template membrane by use of sol-gel chemistry. The TiO2 nanofibrils have good crystallinity and size. There is agglomeration free among the particulates of TiO2 and the fibrils show high catalytic activity.
基金the S˜ao Paulo Research Foundation[FAPESPGrants No.2016/10636-8,2020/07956-6,2018/22214-6,2022/03247-6]+4 种基金the Brazilian National Council for Scientific and Technological Development[CNPqGrants No 001]the European Research Council(ERC)under the European Union’s Horizon 2020 research and innovation program[ERC Advanced Grant Agreement No.788489,“BioElCell”]the Canada Excellence Research Chair Program[CERC-2018-00006]Canada Foundation for Innovation[Project number 38623].
文摘We review the recent progress that have led to the development of porous materials based on cellulose nanostructures found in plants and other resources. In light of the properties that emerge from the chemistry, shape and structural control, we discuss some of the most promising uses of a plant-based material, nanocellulose, in regenerative medicine. Following a brief discussion about the fundamental aspects of self-assembly of nanocellulose precursors, we review the key strategies needed for material synthesis and to adjust the architecture of the materials (using three-dimensional printing, freeze-casted porous materials, and electrospinning) according to their uses in tissue engineering, artificial organs, controlled drug delivery and wound healing systems, among others. For this purpose, we map the structure-property-function relationships of nanocellulose-based porous materials and examine the course of actions that are required to translate innovation from the laboratory to industry. Such efforts require attention to regulatory aspects and market pull. Finally, the key challenges and opportunities in this nascent field are critically reviewed.
基金This work was financially supported by National Natural Science Foundation of China(Grant Nos.U22A20403,22006047)Natural Science Foundation of Hebei Province(E2021203140,B2021203016)Hebei Industrial Innovation and Entrepreneurship team(215A7608D).
文摘Amyloid nanofibrils(ANFs)are supramolecular polymers originally classified as pathological markers in various human degenerative diseases.However,in recent years,ANFs have garnered greater interest and are regarded as nature-based sustainable biomaterials in environmental science,material engineering,and nanotechnology.On a laboratory scale,ANFs can be produced from food proteins via protein unfolding,misfolding,and hydrolysis.Furthermore,ANFs have specific structural characteristics such as a high aspect ratio,good rigidity,chemical stability,and a controllable sequence.These properties make them a promising functional material in water decontamination research.As a result,the fabrication and application of ANFs and their composites in water purification have recently gained considerable attention.Despite the large amount of literature in this field,there is a lack of systematic review to assess the gap in using ANFs and their composites to remove contaminants from water.This review discusses significant advancements in design techniques as well as the physicochemical properties of ANFs-based composites.We also emphasize the current progress in using ANFs-based composites to remove inorganic,organic,and biological contaminants.The interaction mechanisms between ANFs-based composites and contaminants are also highlighted.Finally,we illustrate the challenges and opportunities associated with the future preparation and application of ANFs-based composites.We anticipate that this review will shed new light on the future design and use of ANFs-based composites.
基金This work has been supported by the National Natural Science Foundation of China(32071720)and Key Technology Research and Development Program of Tianjin(19YFZCSN00950)+2 种基金from Tianjin Municipal Science and Technology Bureau,T.Xu thanks the China Postdoctoral Science Foundation(2021M702456)K.Liu acknowledges the financial support from the Tianjin Research Innovation Project for Postgraduate Students(2021YJSB198).W.Liu thanks the China Scholarship Council for the financial support(No.202108120056)and Innovation Project of Excellent Doctoral Dissertation of Tianjin University of Science and Technology(2020005)Open access funding provided by Shanghai Jiao Tong University
文摘Cellulose nanopaper has shown great potential in diverse fields including optoelectronic devices,food packaging,biomedical application,and so forth,owing to their various advantages such as good flexibility,tunable light transmittance,high thermal stability,low thermal expansion coefficient,and superior mechanical properties.Herein,recent progress on the fabrication and applications of cellulose nanopaper is summarized and discussed based on the analyses of the latest studies.We begin with a brief introduction of the three types of nanocellulose:cellulose nanocrystals,cellulose nanofibrils and bacterial cellulose,recapitulating their differences in preparation and properties.Then,the main preparation methods of cellulose nanopaper including filtration method and casting method as well as the newly developed technology are systematically elaborated and compared.Furthermore,the advanced applications of cellulose nanopaper including energy storage,electronic devices,water treatment,and high-performance packaging materials were highlighted.Finally,the prospects and ongoing challenges of cellulose nanopaper were summarized.
文摘Nanoparticles in air are of particular concern for public health and employee exposure in work-places. Therefore, it is very important to prepare effective filters for their removal. In this work filters were prepared from nanocellulose, i.e. cellulose nanofibrils (CNF). CNF was produced using two methods giving two different qualities of CNF. One quality had negative charges on the fibril surfaces while the other was neutral, and had in addition thinner fibrils compared to the other qualities. Filter samples were produced from water dispersions of CNF, by removal of the water by freeze drying. The performance of the CNF based filters was assessed and compared with filters based on synthetic polymer fibres. The ability to collect NaCl particles with a broad size distribution, ranging from nanometer to micrometer scale, was determined. CNF filters showed quality values comparable with the synthetic polymer based filters. Filters based on both the two CNF qualities had very good filtration efficiency for a given pressure drop across the filter.
基金supported by the Fundamental Research Funds for the Central Universities and Graduate Student Innovation Fund of Donghua University(No.CUSF-DH-D2020021).
文摘Fiber morphology with off-standing branches,as found in nature,e.g.,in goose downy feather,provides exquisite functions that can be barely achieved by man-made fiber systems.In this work,we develop a simple and scalable method for generating downy feather-like para-aramid fibers and assemblies.Through treating commercial para-aramid microfibers with mild alkaline solution(low concentration of NaOH),a synergistic effect of chemical hydrolysis and physical shearing is successfully triggered to generate abundant nanofiber branches on the surface of para-aramid fibers.When compared with conventional monotonous structures,nonwovens composed of downy feather-like fibers exhibit a typical multiscale fiber morphology,larger specific surface area and smaller pore size,thus showing enhanced particles adsorption capacity(over twice of the pristine nonwoven),excellent oil absorption capacity(increased by~50%),improved air filtration performances(doubled the filtration efficiency)and effective thermal insulation(thermal conductivity=26.1 mW·m^(−1)·K^(−1)).More attractively,the intrinsic flame-retardant nature of para-aramid is well inherited by the downy feather-like fibers,and the fabrication process requires neither sophisticated equipment,nor tedious procedures,making us believe the strong competitiveness of these fibers and assemblies.
基金This research was supported by National Nature Science Foundation of China(No.51773221)National Key R&D Program of China(No.2018YFB0704200)Youth Innovation Promotion Association CAS(No.2017308).
文摘A tremendous amount of wheat straw(WS)has been generated by wheat crops every year,while only a small percentage is being used in applications,and most get burned on the field,causing a large amount of the exhaust gas that pollutes the environment.Herein,we report on the extraction of cellulose nanofibrils(CNF)from the alkali treated WS by a combination of 2,2,6,6-tetramethylpyperidine-1-oxyl(TEMPO)-oxidation and mechanical disintegration method.The crystalline structures,thermal properties,natural charge of the CNF were examined.The re-sultant nano-building blocks of the CNF was assembled into macroscopic cellulose materials,i.e.,film,aerogel,and filament in this work.Furthermore,the morphologies and microstructues as well as other properties of these three kinds of the CNF assemblies were investigated.The ob-tained CNF and its assemblies showed a potential application in new materials areas.This work explored a new way to utilize the discarded WS instead of being burned.
文摘Waste material from the fishing industry disposed off-shore exceeds 250 billion tons/year, and it is considered hazardous due to its high perishability and polluting effect, both on land and sea. Considering the actual production of chitin, chitosan and oligosaccharides from crustaceons, it is understandable how difficult it is to eliminate all the waste material obtained from food industry, therefore the need for more innovation and creativity. With this in mind we propose an industrial use of the natural chitin nanocrystals (known as chitin-nanofibrils-CN) to produce innovative cosmetics, food supplements and protective films that can improve our way of living while saving the environment.
