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Abstract： Nanocellulose， a kind of cellulose with nanometer sizes， has drawn great interest in the pulp and paper industry due to its unique structure and excellent performance. It can be divided into five categories： nanocrystalline cellulose （NCC）， nanofibrillated cellulose （NFC）， bacterial cellulose （BC）， electrospun cellulose nanofibers （ESC）， and precipitation regenerated cellulose nanofibers （PRC）. In this paper， we reviewed the industrialization progress of nanocellulose in China. Furthermore， we proposed that efficient and environmentally friendly preparation methods and high value utilization would be the focus of nanocellulose development.
Keywords： nanocellulose; nanocrystalline cellulose; nanofibrillated cellulose
1 Introduction
Nanocellulose， which can be obtained through chemical[1-2]， physical[3-4]， and microbiological[5-6] methods， is a kind of cellulose with nanometer sizes[7]. Compared with cellulose fibers， nanocellulose has good biocompatibility， high purity， and high strength in addition to its renewability， non-toxicity， and low density.
Nanocellulose is widely sourced from plants （e.g.， wood， cotton， and flax） and animals （tunicate）. In addition， it can also be obtained by fermentation of microorganisms （e.g.， Acetobacter xylinum）. According to its structure and morphology， it can be divided into five categories： nanocrystalline cellulose （NCC）， nanofibrillated cellulose （NFC）， bacterial cellulose （BC）， electrospun cellulose nanofibers （ESC）， and precipitation regenerated cellulose nanofibers （PRC）.
NCC is a rigid rod-like nanoparticle， having a diameter of 2～20 nm and a length of 100～600 nm. It is usually prepared by acidolysis， which removes the amorphous regions and obtains higher crystallinity while reducing the cellulose size[8-12]. NFC， which is prepared by mechanical methods， has a diameter of 2～40 nm and a length of several micrometers; hence， its aspect ratio is greater than that of NCC. Due to its high-energy consumption， the cellulose is often pretreated chemically or enzymatically and then subjected to high-pressure homogenization or mechanical trituration to obtain NFC. Compared with NCC， NFC has a lower removal rate of amorphous regions， so the crystallinity is lower than that of NCC[13-14]. BC， having a diameter of 20～100 nm， is synthesized by microbiological methods with a network structure， high purity， high average molecular weight， and good mechanical stability. Various bacteria can produce BC， of which Acetobacter xylinum is commonly used[15]. ESC， having a diameter of tens of nanometers to several micrometers， is prepared by electrospinning， which is typically made into film products[16]. PRC is mainly composed of amorphous regions， which is usually prepared by completely dissolving cellulose with a solvent， such as phosphoric acid， and then adding deionized water for regeneration[17-18]. In recent years， nanocellulose has attracted much interest and has played an important role in the pulp and paper industry[19]. It is used to replace ordinary pulp， which saves raw materials and improves paper properties[20]. Moreover， its paper sheets may obtain additional properties[21-23]. This paper summarized the industrialization progress of nanocellulose in China.
2 Research units of nanocellulose
At present， there are several nanocellulose research units in China， as shown in Table 1.
NCNST was founded by the Chinese Academy of Sciences （CAS） and the Ministry of Education on December 31， 2003， with Peking University and Tsinghua University as its initiators and co-founders. In NCNST， basic and applied nanoscience research has been set as the main research directions. It aims to build a public technological platform and research base for nanoscience with state of the art equipment， which is open to domestic and international users.
TIPC focuses on multi-disciplinary fields in physics， chemistry， and engineering technology. As a national institute， it is dedicated to high-technology innovation and technology transfer to serve the national economic and social development. Furthermore， the Research Center for Functional Polymer Materials of TIPC is committed to long-term research of functional cellulose-based materials， including the regulation of crystal structure of cellulose， relationship between structure and morphology of cellulose， and its functional applications.
ICIFP is the only research institute in China that specializes in chemical processing and utilization of forest resources and integrates basic research， applied research， product development， and engineering design. It mainly focuses on nanocellulose preparation， nanocellulose application in environmentally friendly bio-based thermosetting polymer materials， and its functional modification. In addition， it also applies nanocellulose to special film materials， multifunctional fillers， electrochemical sensors， environmentally friendly catalysts， and water treatment materials.
CRIWI has done several research works in environmentally friendly preparation， accurate characterization， and high-value application of lignocellulose nanoparticles under the leadership of Prof. SiQun Wang， which includes the preparation and application of nano lignin， environmentally friendly directional preparation and accurate characterization of nanocellulose. In addition， several frontiers of nanocellulose have been performed in flame retardant and heat insulating aerogel materials， superhydrophobic coating materials， energy storage materials， adsorption materials， and luminescent materials. The State Key Laboratory of Pulp and Paper Engineering of SCUT has greatly contributed to the basic and key technology research in plant resource chemistry and high-value utilization， clean production technology of pulp and paper， specialty paper and functional paper products， pulp and paper equipment and process control， and industrial ecology and environment. Moreover， the State Key Laboratory of Pulp and Paper Engineering of SCUT undertakes more than 10 research projects related to nanocellulose.
CNPPRI has been committed to nanocellulose preparation and application since 2008， which has successfully developed high-concentration carboxyethylation pretreatment technology and medium-concentration mechanical dissociation technology， forming a completely continuous， highly efficient， low-energy consumption， and environmentally friendly nanocellulose preparation process. At the same time， CNPPRI also actively expands nanocellulose applications in papermaking， packaging， composite materials， filtration， and adsorption. It developed nanocellulose products used to enhance composite materials， and improve barrier properties of packaging materials， and proposed MFC/filler pre-flocculation techniques.
YHT has prepared large-scale amorphous nanocellulose for the first time in the world with a low-energy consumption， highly efficient， and pollution-free process. The products can be used as a rheology additive in aqueous coating， humectant in cosmetics， and dietary fiber substitute in foods.
SQG is an innovative enterprise focusing on the research， development， and comprehensive utilization of various plant straws and is involved in biomass， high-performance composite materials， healthcare， and biomedicine. The company is a key high-tech enterprise of the National Torch Program and a national key leading enterprise of agricultural industrialization. In addition， it is recognized by the Ministry of Industry and Information Technology as a national exemplary enterprise in technology innovation. The company is the designated manufacturer of the insulation materials of the return-cabins of the Shenzhou Spacecraft.
3 Academic exchange
The China Technical Association of Paper Industry （CTAPI） actively promotes the research and academic exchange of nanocellulose in China. In 2015， the Nanocellulose and Materials Committee （NMC） of CTAPI was established in NCNST， with Prof. XingYu Jiang appointed as the chairperson. The 2016 and 2017 Annual Meeting of NMC of CTAPI were held in Guangzhou and Hangzhou， China， respectively. The academic conferences about nanocellulose held in China since 2010—2017 are shown in Fig.1. 4 Research progress in nanocellulose
The previous sections have described the major domestic research units of nanocellulose， while this section will summarize the research and development progress of nanocellulose in the recent years， including projects， articles， patents， and industrialization progress.
4.1 Projects
The national key research projects and the main projects supported by National Nature Science Foundation of China （NSFC） are shown in Table 2.
4.2 Articles and patents
In this section， the published nanocellulose research articles and patents are summarized[24]. The statistics of the articles and patents are shown in Table 3. It will be the main trend for the future development of nanocellulose industrialization in its preparation and application technology.
4.3 The main industrialization progress
The earliest nanocellulose plant in mainland China was established in 2011 by the China International Travel Trade Co.， Ltd. （CITTC） and NCNST in Jiamusi， China. Later， other research units also worked on the industrialization of nanocellulose， as shown in Fig.2[25-26].
5 Outlook
In the last decade， nanocellulose has received extensive attention in China due to its excellent performance. Although several nanocellulose plants have been built and trial-tested， there are still various difficulties and challenges during the process from pilot to large-scale production. As an example， nanocrystalline cellulose （NCC） produced by acid hydrolysis has problems in waste treatment， yield， drying， and redispersion while nanofibrillated cellulose （NFC） produced by mechanical methods or enzyme combined with mechanical methods has problems related to energy consumption. Furthermore， the process of TEMPO-oxidized cellulose nanofibers is prone to environmental pollution. Among these， the pollution issues can be addressed through seeking new environmentally friendly reagents or developing a new pollution treatment device while the energy consumption problem can be solved by exploring a new efficient pretreatment method. In addition， bacterial cellulose （BC） can react with various functional groups， so its performance can be improved by modifying the structure. The equipment for preparing electrospun cellulose nanofibers （ESC） needs to be improved to increase its yield. A new preparation process needs to be developed for precipitation regenerated cellulose nanofibers （PRC）. Most importantly， research on nanocellulose in China is still rapidly developing. Therefore， the development of efficient and environmentally friendly preparation methods and the exploration of high value utilization will be the focus of nanocellulose development. Acknowledgments
The authors are grateful for the financial support from the National Natural Science Foundation of China （21875050） .
References
[1] Liu Y， Wang H， Yu G， et al. A novel approach for the preparation of nanocrystalline cellulose by using phosphotungstic acid[J]. Carbohydrate Polymers， 2014， 110（1）： 415-422.
[2] Liu Y Z， Guo B T， Xia Q Q， et al. Efficient Cleavage of Strong Hydrogen Bonds in Cotton by Deep Eutectic Solvents and Facile Fabrication of Cellulose Nanocrystals in High Yields[J]. ACS Sustainable Chemistry & Engineering， 2017， 5（9）： 7623-7631.
[3] Luo X X， Wang X W. Preparation and Characterization of Nanocellulose Fibers from NaOH/Urea Pretreatment of Oil Palm Fibers[J]. Bioresources， 2017， 12（3）： 5826-5837.
[4] Ho T T T， Zimmermann T， Hauert R， et al. Preparation and characterization of cationic nanofibrillated cellulose from etherification and high-shear disintegration processes[J]. Cellulose， 2011， 18（6）： 1391-1406.
[5] Yano S， Maeda H， Nakajima M， et al. Preparation and mechanical properties of bacterial cellulose nanocomposites loaded with silica nanoparticles[J]. Cellulose， 2008， 15（1）： 111-120.
[6] Gao S， Wang J， Jin Z. Preparation of cellulose films from solution of bacterial cellulose in NMMO[J]. Carbohydrate Polymers， 2012， 87（2）： 1020-1025.
[7] Luo H Z， Li J J， Zhou F S. Advances in Hard Tissue Engineering Materials-Nanocellulose-based Composites[J]. Paper and Biomaterials， 2018， 3（4）： 62-76.
[8] Long K Y， Cha R T， Zhang Y P， et al. Cellulose nanocrystals as reinforcements for collagen-based casings with low gas transmission[J]. Cellulose， 2018， 25（1）： 463-471.
[9] Zhang Y P， Zhao Q， Wang H S， et al. Preparation of green and gelatin-free nanocrystalline cellulose capsules[J]. Carbohydrate Polymers， 2017， 164： 358-363.
[10] Cheng S L， Zhang Y P， Cha R T， et al. Water-soluble nanocrystalline cellulose films with highly transparent and oxygen barrier properties[J]. Nanoscale， 2016， 8（2）： 973-978.
[11] Wang C Y， Huang H J， Jia M， et al. Formulation and evaluation of nanocrystalline cellulose as a potential disintegrant[J]. Carbohydrate Polymers， 2015， 130： 275-279.
[12] Cha R T， He Z B， Ni Y H. Preparation and characterization of thermal/pH-sensitive hydrogel from carboxylated nanocrystalline cellulose[J]. Carbohydrate Polymers， 2012， 88（2）：713-718.
[13] Mou K W， Li J J， Wang Y Y， et al. 2，3-Dialdehyde nanofibrillated cellulose as a potential material for the treatment of MRSA infection[J]. Journal of Materials Chemistry B， 2017， 5（38）： 7876-7884. [14] Zhang H， Liu J， Guan M， et al. Nano-fibrillated cellulose （NFC） as a pore size mediator in the preparation of thermal resistant separators for lithium ion batteries[J]. ACS Sustainable Chemistry & Engineering， 2018， 6（4）： 4838-4844.
[15] Wan Z L， Wang L Y， Yang X Q， et al. Enhanced water resistance properties of bacterial cellulose multilayer films by incorporating interlayers of electrospun zein fibers[J]. Food Hydrocolloids， 2016， 61： 269-276.
[16] Li J J， Cha R T， Mou K W， et al. Nanocellulose-Based Antibacterial Materials[J]. Advanced Healthcare Materials， 2018， DOI： 10.1002/adhm.201800334.
[17] Chen J H， Liu J G， Yuan T Q， et al. Comparison of cellulose and chitin nanocrystals for reinforcing regenerated cellulose fibers[J]. Journal of Applied Polymer Science， 2017， DOI： 10.1002/app.44880.
[18] Li Z， Wu H R， Yang M， et al. Stability mechanism of O/W Pickering emulsions stabilized with regenerated cellulose[J]. Carbohydrate Polymers， 2017， 181： 224-233.
[19] Cha R T， Zhang C L. Application of Nanotechnology in Paper Industry[J]. China Pulp & Paper Industry， 2016， 37（21）： 45-52.
[20] Zhang C L， Cha R T， Yang L M， et al. Fabrication of cellulose/graphene paper as a stable-cycling anode materials without collector[J]. Carbohydrate Polymers， 2017， 184： 30-36.
[21] Yang L M， Lu S ， Li J J， et al. Nanocrystalline cellulose-dispersed AKD emulsion for enhancing the mechanical and multiple barrier properties of surface-sized paper[J]. Carbohydrate Polymers， 2016， 136： 1035-1040.
[22] Cha R T， Wang C Y， Cheng S L， et al. Using carboxylated nanocrystalline cellulose as an additive in cellulosic paper and poly（vinyl alcohol） fiber paper[J]. Carbohydrate Polymers， 2014， 110： 298-301.
[23] Cha R T， Wang D， He Z B， et al. Development of cellulose paper testing strips for quick measurement of glucose using chromogen agent[J]. Carbohydrate Polymers， 2012， 88（4）： 1414-1419.
[24] Mou K W， Liu Z Y， Zhou J P， et al. Research Progress in Nanocellulose[J]. Transactions of China Pulp and Paper， 2016， 31（4）： 55-63.
[25] Du H S， Liu C， Zhang M M， et al. Preparation and Industrialization Status of Nanocellulose[J]. Progress in Chemistry， 2018， 30（4）： 448-462.
[26] Wu M. Nanocellulose Research Exchange Activities between China and Japan[J]. Paper and Biomaterials， 2018， 3（4）： 77-78.
Keywords： nanocellulose; nanocrystalline cellulose; nanofibrillated cellulose
1 Introduction
Nanocellulose， which can be obtained through chemical[1-2]， physical[3-4]， and microbiological[5-6] methods， is a kind of cellulose with nanometer sizes[7]. Compared with cellulose fibers， nanocellulose has good biocompatibility， high purity， and high strength in addition to its renewability， non-toxicity， and low density.
Nanocellulose is widely sourced from plants （e.g.， wood， cotton， and flax） and animals （tunicate）. In addition， it can also be obtained by fermentation of microorganisms （e.g.， Acetobacter xylinum）. According to its structure and morphology， it can be divided into five categories： nanocrystalline cellulose （NCC）， nanofibrillated cellulose （NFC）， bacterial cellulose （BC）， electrospun cellulose nanofibers （ESC）， and precipitation regenerated cellulose nanofibers （PRC）.
NCC is a rigid rod-like nanoparticle， having a diameter of 2～20 nm and a length of 100～600 nm. It is usually prepared by acidolysis， which removes the amorphous regions and obtains higher crystallinity while reducing the cellulose size[8-12]. NFC， which is prepared by mechanical methods， has a diameter of 2～40 nm and a length of several micrometers; hence， its aspect ratio is greater than that of NCC. Due to its high-energy consumption， the cellulose is often pretreated chemically or enzymatically and then subjected to high-pressure homogenization or mechanical trituration to obtain NFC. Compared with NCC， NFC has a lower removal rate of amorphous regions， so the crystallinity is lower than that of NCC[13-14]. BC， having a diameter of 20～100 nm， is synthesized by microbiological methods with a network structure， high purity， high average molecular weight， and good mechanical stability. Various bacteria can produce BC， of which Acetobacter xylinum is commonly used[15]. ESC， having a diameter of tens of nanometers to several micrometers， is prepared by electrospinning， which is typically made into film products[16]. PRC is mainly composed of amorphous regions， which is usually prepared by completely dissolving cellulose with a solvent， such as phosphoric acid， and then adding deionized water for regeneration[17-18]. In recent years， nanocellulose has attracted much interest and has played an important role in the pulp and paper industry[19]. It is used to replace ordinary pulp， which saves raw materials and improves paper properties[20]. Moreover， its paper sheets may obtain additional properties[21-23]. This paper summarized the industrialization progress of nanocellulose in China.
2 Research units of nanocellulose
At present， there are several nanocellulose research units in China， as shown in Table 1.
NCNST was founded by the Chinese Academy of Sciences （CAS） and the Ministry of Education on December 31， 2003， with Peking University and Tsinghua University as its initiators and co-founders. In NCNST， basic and applied nanoscience research has been set as the main research directions. It aims to build a public technological platform and research base for nanoscience with state of the art equipment， which is open to domestic and international users.
TIPC focuses on multi-disciplinary fields in physics， chemistry， and engineering technology. As a national institute， it is dedicated to high-technology innovation and technology transfer to serve the national economic and social development. Furthermore， the Research Center for Functional Polymer Materials of TIPC is committed to long-term research of functional cellulose-based materials， including the regulation of crystal structure of cellulose， relationship between structure and morphology of cellulose， and its functional applications.
ICIFP is the only research institute in China that specializes in chemical processing and utilization of forest resources and integrates basic research， applied research， product development， and engineering design. It mainly focuses on nanocellulose preparation， nanocellulose application in environmentally friendly bio-based thermosetting polymer materials， and its functional modification. In addition， it also applies nanocellulose to special film materials， multifunctional fillers， electrochemical sensors， environmentally friendly catalysts， and water treatment materials.
CRIWI has done several research works in environmentally friendly preparation， accurate characterization， and high-value application of lignocellulose nanoparticles under the leadership of Prof. SiQun Wang， which includes the preparation and application of nano lignin， environmentally friendly directional preparation and accurate characterization of nanocellulose. In addition， several frontiers of nanocellulose have been performed in flame retardant and heat insulating aerogel materials， superhydrophobic coating materials， energy storage materials， adsorption materials， and luminescent materials. The State Key Laboratory of Pulp and Paper Engineering of SCUT has greatly contributed to the basic and key technology research in plant resource chemistry and high-value utilization， clean production technology of pulp and paper， specialty paper and functional paper products， pulp and paper equipment and process control， and industrial ecology and environment. Moreover， the State Key Laboratory of Pulp and Paper Engineering of SCUT undertakes more than 10 research projects related to nanocellulose.
CNPPRI has been committed to nanocellulose preparation and application since 2008， which has successfully developed high-concentration carboxyethylation pretreatment technology and medium-concentration mechanical dissociation technology， forming a completely continuous， highly efficient， low-energy consumption， and environmentally friendly nanocellulose preparation process. At the same time， CNPPRI also actively expands nanocellulose applications in papermaking， packaging， composite materials， filtration， and adsorption. It developed nanocellulose products used to enhance composite materials， and improve barrier properties of packaging materials， and proposed MFC/filler pre-flocculation techniques.
YHT has prepared large-scale amorphous nanocellulose for the first time in the world with a low-energy consumption， highly efficient， and pollution-free process. The products can be used as a rheology additive in aqueous coating， humectant in cosmetics， and dietary fiber substitute in foods.
SQG is an innovative enterprise focusing on the research， development， and comprehensive utilization of various plant straws and is involved in biomass， high-performance composite materials， healthcare， and biomedicine. The company is a key high-tech enterprise of the National Torch Program and a national key leading enterprise of agricultural industrialization. In addition， it is recognized by the Ministry of Industry and Information Technology as a national exemplary enterprise in technology innovation. The company is the designated manufacturer of the insulation materials of the return-cabins of the Shenzhou Spacecraft.
3 Academic exchange
The China Technical Association of Paper Industry （CTAPI） actively promotes the research and academic exchange of nanocellulose in China. In 2015， the Nanocellulose and Materials Committee （NMC） of CTAPI was established in NCNST， with Prof. XingYu Jiang appointed as the chairperson. The 2016 and 2017 Annual Meeting of NMC of CTAPI were held in Guangzhou and Hangzhou， China， respectively. The academic conferences about nanocellulose held in China since 2010—2017 are shown in Fig.1. 4 Research progress in nanocellulose
The previous sections have described the major domestic research units of nanocellulose， while this section will summarize the research and development progress of nanocellulose in the recent years， including projects， articles， patents， and industrialization progress.
4.1 Projects
The national key research projects and the main projects supported by National Nature Science Foundation of China （NSFC） are shown in Table 2.
4.2 Articles and patents
In this section， the published nanocellulose research articles and patents are summarized[24]. The statistics of the articles and patents are shown in Table 3. It will be the main trend for the future development of nanocellulose industrialization in its preparation and application technology.
4.3 The main industrialization progress
The earliest nanocellulose plant in mainland China was established in 2011 by the China International Travel Trade Co.， Ltd. （CITTC） and NCNST in Jiamusi， China. Later， other research units also worked on the industrialization of nanocellulose， as shown in Fig.2[25-26].
5 Outlook
In the last decade， nanocellulose has received extensive attention in China due to its excellent performance. Although several nanocellulose plants have been built and trial-tested， there are still various difficulties and challenges during the process from pilot to large-scale production. As an example， nanocrystalline cellulose （NCC） produced by acid hydrolysis has problems in waste treatment， yield， drying， and redispersion while nanofibrillated cellulose （NFC） produced by mechanical methods or enzyme combined with mechanical methods has problems related to energy consumption. Furthermore， the process of TEMPO-oxidized cellulose nanofibers is prone to environmental pollution. Among these， the pollution issues can be addressed through seeking new environmentally friendly reagents or developing a new pollution treatment device while the energy consumption problem can be solved by exploring a new efficient pretreatment method. In addition， bacterial cellulose （BC） can react with various functional groups， so its performance can be improved by modifying the structure. The equipment for preparing electrospun cellulose nanofibers （ESC） needs to be improved to increase its yield. A new preparation process needs to be developed for precipitation regenerated cellulose nanofibers （PRC）. Most importantly， research on nanocellulose in China is still rapidly developing. Therefore， the development of efficient and environmentally friendly preparation methods and the exploration of high value utilization will be the focus of nanocellulose development. Acknowledgments
The authors are grateful for the financial support from the National Natural Science Foundation of China （21875050） .
References
[1] Liu Y， Wang H， Yu G， et al. A novel approach for the preparation of nanocrystalline cellulose by using phosphotungstic acid[J]. Carbohydrate Polymers， 2014， 110（1）： 415-422.
[2] Liu Y Z， Guo B T， Xia Q Q， et al. Efficient Cleavage of Strong Hydrogen Bonds in Cotton by Deep Eutectic Solvents and Facile Fabrication of Cellulose Nanocrystals in High Yields[J]. ACS Sustainable Chemistry & Engineering， 2017， 5（9）： 7623-7631.
[3] Luo X X， Wang X W. Preparation and Characterization of Nanocellulose Fibers from NaOH/Urea Pretreatment of Oil Palm Fibers[J]. Bioresources， 2017， 12（3）： 5826-5837.
[4] Ho T T T， Zimmermann T， Hauert R， et al. Preparation and characterization of cationic nanofibrillated cellulose from etherification and high-shear disintegration processes[J]. Cellulose， 2011， 18（6）： 1391-1406.
[5] Yano S， Maeda H， Nakajima M， et al. Preparation and mechanical properties of bacterial cellulose nanocomposites loaded with silica nanoparticles[J]. Cellulose， 2008， 15（1）： 111-120.
[6] Gao S， Wang J， Jin Z. Preparation of cellulose films from solution of bacterial cellulose in NMMO[J]. Carbohydrate Polymers， 2012， 87（2）： 1020-1025.
[7] Luo H Z， Li J J， Zhou F S. Advances in Hard Tissue Engineering Materials-Nanocellulose-based Composites[J]. Paper and Biomaterials， 2018， 3（4）： 62-76.
[8] Long K Y， Cha R T， Zhang Y P， et al. Cellulose nanocrystals as reinforcements for collagen-based casings with low gas transmission[J]. Cellulose， 2018， 25（1）： 463-471.
[9] Zhang Y P， Zhao Q， Wang H S， et al. Preparation of green and gelatin-free nanocrystalline cellulose capsules[J]. Carbohydrate Polymers， 2017， 164： 358-363.
[10] Cheng S L， Zhang Y P， Cha R T， et al. Water-soluble nanocrystalline cellulose films with highly transparent and oxygen barrier properties[J]. Nanoscale， 2016， 8（2）： 973-978.
[11] Wang C Y， Huang H J， Jia M， et al. Formulation and evaluation of nanocrystalline cellulose as a potential disintegrant[J]. Carbohydrate Polymers， 2015， 130： 275-279.
[12] Cha R T， He Z B， Ni Y H. Preparation and characterization of thermal/pH-sensitive hydrogel from carboxylated nanocrystalline cellulose[J]. Carbohydrate Polymers， 2012， 88（2）：713-718.
[13] Mou K W， Li J J， Wang Y Y， et al. 2，3-Dialdehyde nanofibrillated cellulose as a potential material for the treatment of MRSA infection[J]. Journal of Materials Chemistry B， 2017， 5（38）： 7876-7884. [14] Zhang H， Liu J， Guan M， et al. Nano-fibrillated cellulose （NFC） as a pore size mediator in the preparation of thermal resistant separators for lithium ion batteries[J]. ACS Sustainable Chemistry & Engineering， 2018， 6（4）： 4838-4844.
[15] Wan Z L， Wang L Y， Yang X Q， et al. Enhanced water resistance properties of bacterial cellulose multilayer films by incorporating interlayers of electrospun zein fibers[J]. Food Hydrocolloids， 2016， 61： 269-276.
[16] Li J J， Cha R T， Mou K W， et al. Nanocellulose-Based Antibacterial Materials[J]. Advanced Healthcare Materials， 2018， DOI： 10.1002/adhm.201800334.
[17] Chen J H， Liu J G， Yuan T Q， et al. Comparison of cellulose and chitin nanocrystals for reinforcing regenerated cellulose fibers[J]. Journal of Applied Polymer Science， 2017， DOI： 10.1002/app.44880.
[18] Li Z， Wu H R， Yang M， et al. Stability mechanism of O/W Pickering emulsions stabilized with regenerated cellulose[J]. Carbohydrate Polymers， 2017， 181： 224-233.
[19] Cha R T， Zhang C L. Application of Nanotechnology in Paper Industry[J]. China Pulp & Paper Industry， 2016， 37（21）： 45-52.
[20] Zhang C L， Cha R T， Yang L M， et al. Fabrication of cellulose/graphene paper as a stable-cycling anode materials without collector[J]. Carbohydrate Polymers， 2017， 184： 30-36.
[21] Yang L M， Lu S ， Li J J， et al. Nanocrystalline cellulose-dispersed AKD emulsion for enhancing the mechanical and multiple barrier properties of surface-sized paper[J]. Carbohydrate Polymers， 2016， 136： 1035-1040.
[22] Cha R T， Wang C Y， Cheng S L， et al. Using carboxylated nanocrystalline cellulose as an additive in cellulosic paper and poly（vinyl alcohol） fiber paper[J]. Carbohydrate Polymers， 2014， 110： 298-301.
[23] Cha R T， Wang D， He Z B， et al. Development of cellulose paper testing strips for quick measurement of glucose using chromogen agent[J]. Carbohydrate Polymers， 2012， 88（4）： 1414-1419.
[24] Mou K W， Liu Z Y， Zhou J P， et al. Research Progress in Nanocellulose[J]. Transactions of China Pulp and Paper， 2016， 31（4）： 55-63.
[25] Du H S， Liu C， Zhang M M， et al. Preparation and Industrialization Status of Nanocellulose[J]. Progress in Chemistry， 2018， 30（4）： 448-462.
[26] Wu M. Nanocellulose Research Exchange Activities between China and Japan[J]. Paper and Biomaterials， 2018， 3（4）： 77-78.