Method for large-scale preparation of cellulose nanocrystals with high yield, and product thereof

Abstract

Provided in the present invention are a novel method for preparing cellulose nanocrystals (CNCs) and a product thereof, belonging to the technical field of novel manufacturing. The method of the present invention comprises co-milling a cellulose raw material and a selective water-soluble molecule to form specific composite micelles, and then performing subsequent degradation and stripping and / or phase separation on the composite micelles to obtain cellulose nanocrystals. The cellulose nanocrystals (CNCs) are produced in a large scale with an extremely low amount of dilute acids, an ultra-high yield, extremely low environmental impact and low costs.

Description

A method and product for high-yield, large-scale preparation of cellulose nanocrystals Technical Field

[0001] This invention provides a method for producing cellulose nanocrystals, achieving high yield and large-scale production of cellulose nanocrystal products. It belongs to the field of novel manufacturing technology. Background Technology

[0002] Nanocellulose is an emerging nanomaterial prepared from cellulose raw materials, with diameters ranging in the nanometer range and lengths in the micrometer or nanometer range. It mainly includes cellulose nanofibers (CNF), cellulose nanocrystals (CNC), and bacterial nanocelluloses (BNC). Nanocellulose possesses excellent properties, such as a specific aspect ratio, large specific surface area, ultra-high mechanical strength, excellent biocompatibility, rheological properties, chemical amphiphilicity, optical and dielectric properties, etc. Nanocellulose can be obtained from various sources, such as wood, bagasse, cotton, waste paper, hemp, rice husks, straw, algae, bamboo, reeds, fruits and vegetables, and agricultural waste. It has wide applications in various industrial fields, food and nutrition, medicine, biomedical materials, daily chemical and cosmetic products, chemical industry, high-end coatings, aerospace, automotive and shipbuilding, new energy materials, building materials, packaging materials, image display and printing, 3D printing, aerogels, agricultural materials, optical materials, electronic materials, and many other industries.

[0003] Cellulose cellulose (CNC) molecules range in diameter from 5-50 nm, typically 5-30 nm, and in length from 20-900 nm, exhibiting rod-like or needle-like morphology. Current CNC preparation methods primarily utilize strong acid hydrolysis, such as with 60%-74% sulfuric acid. The waste acid and wastewater generated during this process pose significant environmental challenges. Furthermore, the concentrated acid hydrolysis and purification processes impose extremely stringent safety and cost requirements on equipment and processes. A major problem is the extremely low yield of cellulose CNCs produced, approximately only 15%-30%. All these factors have prevented large-scale, economical, and commercial production of cellulose CNCs globally for a long time. Another challenge brought by strong acid hydrolysis, such as with concentrated sulfuric acid or concentrated nitric acid, is the partial substitution of hydroxyl groups on the cellulose CNC molecules by strong acid groups, leading to potential biotoxicity and health risks.

[0004] Therefore, existing technologies have not yet enabled the large-scale, economical, and commercial production of cellulose nanocrystals (CNC). Summary of the Invention

[0005] This invention provides a novel method for preparing cellulose nanocrystals (CNCs) with extremely low dilute acid usage, ultra-high yield, and extremely low environmental impact, thereby truly achieving low-cost, large-scale industrial production of cellulose nanocrystals (CNCs).

[0006] This invention is achieved through the following technical solution:

[0007] The invention provides a method for producing cellulose nanocrystals, characterized by the step of preparing a specific cellulose micelle dispersion from cellulose raw materials and selectively water-soluble molecules, wherein the specific cellulose micelles are 50% or more by weight of cellulose micelles in water with a particle size of less than 1000 nanometers; preferably, 70% or more by weight of cellulose micelles in water with a particle size of less than 1000 nanometers; preferably, 90% or more by weight of cellulose micelles in water with a particle size of less than 1000 nanometers; preferably, 97% or more by weight of cellulose micelles in water with a particle size of less than 1000 nanometers.

[0008] Preferably, in the method described above, the cellulose raw material is hydrolyzed cellulose or commercially available cellulose.

[0009] Preferably, in the method described above, the degree of polymerization of the hydrolyzed cellulose is controlled at 50-300 glucose units, more preferably 100-250 glucose units.

[0010] Preferably, in the method described above, the hydrolyzed cellulose is obtained from plant cellulose of any source through low-acid hydrolysis; preferably, hydrolyzed cellulose is prepared using a diluted inorganic acid hydrolysis method; preferably, the acid concentration is 0.1%-10%; more preferably, it is a 0.1%-1% concentration of dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, etc.

[0011] Preferably, in the method described above, the commercially available cellulose is selected from microcrystalline cellulose plus sodium carboxymethyl cellulose composite colloid, microcrystalline cellulose plus xanthan gum composite colloid, microcrystalline cellulose plus sodium alginate composite colloid, microcrystalline cellulose plus carrageenan composite colloid, microcrystalline cellulose plus pectin composite colloid, microcrystalline cellulose plus guar gum composite colloid, microcrystalline cellulose plus modified starch composite colloid, etc.

[0012] Preferably, in the method described above, the selective water-soluble molecules are selected from: carboxymethyl cellulose and its salts; water-soluble cellulose ethers such as hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, etc.; natural water-soluble molecules such as starch, sodium alginate, pectin, carrageenan, xanthan gum, chitosan, water-soluble plant protein, water-soluble animal protein, etc.; synthetic polymers such as polyvinyl alcohol, polyethylene glycol, povidone (polyvinylpyrrolidone), copovidone, poloxamer (polyoxyethylene polyoxypropylene ether block copolymer), carbomer (polyacrylic acid), polyacrylamide, polyethyleneimine, polyethyleneamine, etc.; water-soluble salts such as sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, aluminum chloride, ammonium chloride, zinc chloride, ferric chloride, copper chloride, zirconium chloride, sodium carbonate, zirconium carbonate, magnesium sulfate, aluminum sulfate, copper sulfate, ferric sulfate, zirconium sulfate, organic quaternary ammonium salts, etc.; and water molecules themselves such as liquid water and solid ice.

[0013] Preferably, the method for producing cellulose nanocrystals described above further includes the steps of optionally enzymatically hydrolyzing the cellulose micelles, optionally degrading and peeling them, purifying them, and separating them into phases to obtain the cellulose nanocrystal product.

[0014] As one of the preferred embodiments of the present invention, the method described above includes the following steps:

[0015] (1) The specific cellulose micelle dispersion is prepared by co-milling and / or forcefully shearing cellulose raw materials and selective water-soluble molecules;

[0016] (2) Remove particles with a particle size greater than and / or equal to 1000 nm from the cellulose micelle dispersion prepared in step (1) by centrifugation or filtration to obtain a centrifuged supernatant or filtrate with a particle size less than 1000 nm.

[0017] (3) The supernatant or filtrate obtained in step (2) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation is carried out by oxidation reaction using hydrogen peroxide;

[0018] (4) The hydrolyzed cellulose nanoparticle suspension obtained in step (3) is centrifuged or filtered, and a concentrated solution or wet cake of cellulose nanocrystals is obtained from the centrifuged sediment or the filtered cake to obtain the cellulose nanocrystal product.

[0019] Alternatively, as one of the preferred embodiments of the present invention, the method described above includes the following steps:

[0020] (1) The specific cellulose micelle dispersion is prepared by co-milling and / or forcefully shearing cellulose raw materials and selective water-soluble molecules;

[0021] (2) Remove particles with a particle size greater than and / or equal to 1000 nm from the cellulose micelle dispersion prepared in step (1) by centrifugation or filtration to obtain a centrifuged supernatant or filtrate with a particle size less than 1000 nm.

[0022] (3) The centrifuged supernatant or filtrate obtained in step (2) is concentrated or dried to obtain a composite cellulose nanocrystal product containing selective water-soluble molecules.

[0023] Alternatively, as one of the preferred embodiments of the present invention, the method described above includes the following steps:

[0024] (1) The specific cellulose micelle dispersion is prepared by co-milling and / or forcefully shearing cellulose raw materials and selective water-soluble molecules;

[0025] (2) The cellulose micelle dispersion obtained in step (1) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation are carried out by oxidation reaction using hydrogen peroxide;

[0026] (3) The hydrolyzed cellulose nanoparticle suspension obtained in step (2) is centrifuged or filtered, and a concentrated liquid or wet cake of cellulose nanocrystals is obtained from the centrifuged sediment or the filtered cake to obtain the cellulose nanocrystal product.

[0027] Alternatively, as one of the preferred embodiments of the present invention, the method described above includes the following steps:

[0028] (1) The cellulose raw material is co-milled and / or subjected to strong shearing with water molecules or water-soluble salts to prepare the specific cellulose micelle dispersion described above;

[0029] (2) The cellulose micelle dispersion obtained in step (1) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation is carried out using an ultra-strong shear mechanical degradation and exfoliation method; more preferably, the degradation and exfoliation is carried out using high-pressure homogenization.

[0030] (3) Centrifuge or filter the hydrolyzed cellulose nanoparticle suspension obtained in step (2), and obtain a concentrated solution or wet cake of cellulose nanocrystals from the centrifuged sediment or the filtered cake to obtain the cellulose nanocrystal product.

[0031] The degradation and stripping described above are selected from any one or a combination of oxidation, enzymatic hydrolysis, acid degradation, alkaline degradation, microbial degradation, and high-intensity shear mechanical degradation.

[0032] The centrifugation described above can be a centrifugal sedimentation method or a centrifugal filtration method. The centrifugation can be single-stage, multi-stage, or cyclic centrifugation.

[0033] In the method described above in this invention, the diameter of the dispersed cellulose nanocrystal product is 5-50 nanometers, preferably 5-30 nanometers; the length is 20-900 nanometers, preferably 50-400 nanometers.

[0034] This invention provides a method for preparing cellulose nanocrystals by co-milling and / or forcefully shearing cellulose raw materials with selective water-soluble molecules to form specific cellulose micelles (or composite micelles), and then by combining subsequent degradation and exfoliation of the composite micelles with phase separation methods. The yield of cellulose nanocrystal products relative to cellulose raw materials reaches more than 60%, preferably 63%-97%.

[0035] In this invention, the hydrolyzed cellulose raw material can be any plant cellulose source, and the degree of polymerization of the hydrolyzed cellulose is generally controlled at 50-300 glucose units, preferably 100-250 glucose units. In this invention, the preparation method of hydrolyzed cellulose can be a well-known weak acid hydrolysis method, or it can include any of the following methods and combinations: hydrolysis with various inorganic acids, hydrolysis with various organic acids or organic anhydrides, solid acid hydrolysis, hydrolysis with various organic sulfonic acids, various oxidative hydrolysis, hydrolysis with various polymetallic oxometalates (POMs) or metal heteropolyacids, enzymatic hydrolysis, various oxygen-catalyzed hydrolysis, ultraviolet photocatalyzed oxidative hydrolysis, electron beam radiation hydrolysis, and various ionic liquid hydrolysis, etc. If a diluted inorganic acid hydrolysis method is used to prepare hydrolyzed cellulose, such as hydrochloric acid, sulfuric acid, or nitric acid, the concentration of the inorganic acid used is usually only about 0.1%-1%, but it can also be selected as 1%-10% as needed.

[0036] In this invention, selectively water-soluble molecules include water-soluble natural polymers, synthetic polymers, or their oligomers, as well as water-soluble inorganic salts, organic salts, and water-soluble sugars and sugar alcohols. As an extreme example, selectively water-soluble molecules also include water molecules themselves, such as ice and liquid water. The natural polymers used in this invention include polysaccharide polymers and their derivatives, water-soluble plant proteins, and animal protein polymers. Examples include: carboxymethyl cellulose and its salts, natural and modified starches, maltodextrin, water-soluble cellulose ethers (HPC, HEC, HPMC, MC), water-soluble alginate, high-ester and low-ester pectin, carrageenan, xanthan gum, guar gum, gum arabic, tamarind gum, soybean polysaccharides, chitosan, various plant glucans, xylan, galactomannan, glucomannan, agar, water-soluble soybean protein, water-soluble milk protein, hydrolyzed collagen, gelatin, etc. The synthetic polymers used in this invention include polyvinyl alcohol, polyethylene glycol, povidone (polyvinylpyrrolidone), copovidone, poloxamer (polyoxyethylene polyoxypropylene ether block copolymer), carbomer (polyacrylic acid), polyacrylamide, polyethyleneimine, and polyethyleneamine. The water-soluble salts used in this invention include: sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, aluminum chloride, ammonium chloride, zinc chloride, ferric chloride, copper chloride, zirconium chloride, sodium carbonate, zirconium carbonate, magnesium sulfate, aluminum sulfate, copper sulfate, ferric sulfate, zirconium sulfate, lignin sulfonate, polystyrene sulfate, and organic quaternary ammonium salts.

[0037] In this invention, the co-milling equipment can be one or a combination of two or more of the following: an extruder, a kneader, a kneading extruder, a press, a roller press, a high-pressure homogenizer, a high-pressure homogenizing pump, a high-pressure micro-jet homogenizer, a fine grinding mill, a colloid mill or ball mill, a planetary mill, and a high-shear wall-breaking machine. The high-shear equipment can be a wall-breaking machine, etc.

[0038] In this invention, in the specific composite micelles (or specific cellulose micelles), more than 50% by weight of the hydrolyzed cellulose micelles have a particle size of less than 1000 nanometers in water. Preferably, more than 70% by weight of the hydrolyzed cellulose micelles have a particle size of less than 1000 nanometers in water; more preferably, more than 90% by weight of the hydrolyzed cellulose micelles have a particle size of less than 1000 nanometers in water; most preferably, more than 97% by weight of the hydrolyzed cellulose micelles have a particle size of less than 1000 nanometers in water. While the particle size of hydrolyzed cellulose micelles in water is less than 1000 nanometers, falling within the nanometer length range, the final cellulose nanocrystal product of this invention has a particle length of less than 1000 nanometers in more than 99% or 100% of its particles, preferably less than 800 nanometers, and more preferably less than 400 nanometers.

[0039] The composite micelle material formed by co-milling hydrolyzed cellulose of the present invention can be a wet material or a dried product, and also includes commercially available specific colloidal microcrystalline cellulose products that meet the above-mentioned characteristics of hydrolyzed cellulose composite micelles (e.g., colloidal microcrystalline cellulose with sodium carboxymethyl cellulose, colloidal microcrystalline cellulose with xanthan gum, colloidal microcrystalline cellulose with sodium alginate, colloidal microcrystalline cellulose with carrageenan, colloidal microcrystalline cellulose with guar gum, colloidal microcrystalline cellulose with pectin, colloidal microcrystalline cellulose with modified starch, etc.).

[0040] In this invention, the subsequent method for degrading and stripping hydrolyzed cellulose micelles, i.e., the specific cellulose micelles mentioned above, includes methods or combinations thereof from the surface of hydrolyzed cellulose micro / nanoparticles, such as oxidation, enzymatic hydrolysis, acidic degradation, alkaline degradation, microbial degradation, and ultra-strong shear mechanical degradation, thereby degrading and stripping water-soluble molecules or destroying the hydrated paste-like micelle system, and transferring and dissolving the degraded and stripped molecules into the aqueous phase. The oxidative degradation methods include the oxidation of any peroxide and its catalytic oxidation, such as hydrogen peroxide, organic peroxides, various persulfates and their salts, various persulfates and their salts, percarbonates and their salts, peracetic acid, etc.; also including chemically generated or photochemical / radiochemically generated hydroxyl radicals, ozone, hypochlorous acid and its salts, chlorine, chlorine dioxide, etc.; among which hydrogen peroxide oxidation or its catalytic oxidation, various persulfates and their salts, various persulfates and their salts, ozone, hypochlorous acid and its salts, etc., are preferred methods. The type of enzyme used for the degradation of water-soluble molecules depends on the characteristics of the selected molecule. For example, if the water-soluble molecule is sodium carboxymethyl cellulose, various cellulases can be used; if the water-soluble molecule is starch or modified starch, amylase can be selected for degradation; if the water-soluble molecule is protein, protease can be selected for degradation. Preferably, the water-soluble molecule can be selected as various polysaccharides, and thus can be degraded using polysaccharide hydrolases. If there is no effective degrading enzyme for the water-soluble molecule, a controlled combination of endo- and exo-cellulases can be used to selectively degrade and hydrolyze the surface of cellulose, which can also achieve the stripping of water-soluble molecules to a certain extent. Enzymatic degradation is employed, including enzymes matched to the water-soluble molecule, such as cellulase, hemi-cellulase, amylase, and protease. The amount of enzyme used is generally 0.001%-10%, preferably 0.001%-2%. Acidic degradation includes inorganic acids, organic acids, metal oxide salts (POMs), and metal heteropolyacids. Alkaline degradation includes sodium hydroxide, potassium hydroxide, ammonium hydroxide or ammonia, sodium carbonate, calcium hydroxide, etc., with the amount of alkali typically ranging from 2% to 20%, preferably 5% to 10%. High-shear mechanical degradation methods include high-pressure homogenization at pressures above 40 MPa, such as high-pressure homogenization at pressures of 40-150 MPa; preferably high-pressure homogenization at pressures above 60 MPa, more preferably high-pressure homogenization at pressures above 80 MPa; and also include supersonic microjets high-pressure homogenization. In this invention, if diluted inorganic acids (such as hydrochloric acid, sulfuric acid, nitric acid) are used to degrade water-soluble molecules, the concentration of the inorganic acid is selected to be 0.1% to 10%, typically around 0.1% to 1%. In this invention, if oxidants (such as hydrogen peroxide, organic peroxides, various persulfates and their salts, various monosulfates and their salts) are used to oxidize and degrade water-soluble molecules, the amount of oxidant relative to the weight of the composite micelles of hydrolyzed cellulose and selectively water-soluble molecules is generally 1% to 30%, typically 5% to 20%.In the present invention, when using a bio-enzyme to precipitate water-soluble molecules, the dosage of the bio-enzyme is generally 0.001%-10%, usually 0.001%-2%, relative to the weight of the composite micelles of hydrolyzed cellulose and selectively water-soluble molecules.

[0041] In the present invention, after the above-mentioned hydrolyzed cellulose micelles are degraded and peeled off, the subsequent corresponding phase separation methods include various centrifugal separations, various filtration separations, and various sedimentation separations, etc. Various centrifugal separations include: various tubular centrifugal separations, various bag-type filtration centrifugal separations, various plate centrifugal separations, various disc centrifugal separations, vane centrifugal separations, various sedimentation centrifugal separations, vertical or horizontal centrifugal separations, continuous or intermittent centrifugal separations, centrifugal filtration separations, and also include filtration systems supporting various centrifuges, as well as various drums and various mechanical separation discharging and slag discharging devices. Various filtration separations include vacuum filtration, various pressure filtrations, liquid infiltration pressure filtration, roll filtration, various belt filtrations, various bag filtrations, various membrane filtrations, microfiltration, dialysis filtration, osmotic filtration, ultrafiltration, etc.

[0042] The preparation method of cellulose nanocrystals in the present invention generally includes or partially includes the following steps:

[0043] 1. Prepare composite micelles formed by co-milling hydrolyzed cellulose and selectively water-soluble molecules; or form a dispersion by subjecting commercially available colloidal microcrystalline cellulose products that meet the characteristics of the aforementioned hydrolyzed cellulose composite micelles to high-shear force.

[0044] 2. Optionally, remove particles with a particle size greater than or equal to 1000 nm in the composite micelles or dispersion in step 1 by centrifugation or filtration, so as to obtain a centrifugal supernatant or filtrate with a particle size less than 1000 nm.

[0045] 3. Subject the dispersion in step 1 or the centrifugal supernatant or filtrate in step 2 to degradation or oxidative peeling to break the micelle solution of hydrolyzed cellulose and the attached water-soluble molecules, and at the same time further reduce the cellulose particle size, so as to obtain a suspension of nanoparticles of hydrolyzed cellulose.

[0046] 4. Subject the suspension of nanoparticles of hydrolyzed cellulose in step 3 to centrifugation or centrifugal filtration to obtain a concentrated solution or wet cake of cellulose nanocrystals as the cellulose nanocrystal product.

[0047] 5. Optionally, the centrifugal supernatant or filtrate in step 2 can also be further concentrated or dried to prepare a composite cellulose nanocrystal product containing water-soluble molecules.

[0048] If the selectively water-soluble molecule is water molecule itself or water-soluble salts, the preparation method includes the following steps:

[0049] (1) Hydrolyzed cellulose is co-milled with water molecules or water-soluble salts and then subjected to strong shearing to form a hydrated cellulose paste-like micelle dispersion.

[0050] (2) The paste-like micelle dispersion in step (1) is further oxidized, enzymatically hydrolyzed or mechanically degraded under high pressure to break down the hydrated paste and obtain a suspension of hydrolyzed cellulose nanoparticles.

[0051] (3) Centrifuge or centrifuge filter the nanoparticle suspension in step (2) to obtain a concentrated liquid or wet cake of cellulose nanocrystals, thereby obtaining cellulose nanocrystal products.

[0052] In the above-mentioned cellulose nanocrystal products, the diameter of the nanocellulose crystal particles is 5-50 nanometers, preferably 5-30 nanometers; the length of the particles is 20-900 nanometers, preferably 50-400 nanometers.

[0053] In the above-mentioned composite cellulose nanocrystal products containing water-soluble molecules, the diameter of the nanocellulose crystal particles is 5-50 nanometers; the length of the particles is 20-900 nanometers, preferably 50-400 nanometers.

[0054] The hydrolyzed cellulose centrifugal residue or hydrolyzed cellulose filtration waste obtained during the phase separation processes such as centrifugation and centrifugal filtration in the above steps can be further dried to produce separate cellulose products (including but not limited to microcrystalline cellulose), or it can be returned or recycled as raw material in the production process of co-milling composite micelles of hydrolyzed cellulose and water-soluble molecules. This further improves the yield of cellulose nanocrystals and the full utilization of materials.

[0055] The cellulose nanocrystal production process of this invention has an extremely high yield. Most steps involve physical losses, and the yield depends solely on the operator's skill and recovery rate. In the oxidation, degradation, and exfoliation steps, the main losses are the consumption of selectively water-soluble molecules and a small amount of cellulose degradation. The yield depends primarily on the amount of selective water molecules used, preferably 2%-15%. In extreme cases, water may be used exclusively as the selective water-soluble molecule, thus eliminating the consumption of water-soluble molecules. Overall, based on cellulose raw materials, the yield can reach over 60%, preferably 63%-97%, far exceeding the 15%-30% yield of traditional cellulose nanocrystal preparation methods. In fact, as described above, in the various production process schemes of the cellulose nanocrystals of this invention, the resulting centrifugal filtration residue and residual materials in the equipment can be further collected and returned or recycled as raw materials, or used as separate cellulose products. Therefore, in this invention, apart from the loss of water-soluble molecules, the cellulose material itself is almost completely and fully utilized.

[0056] The solid content of the cellulose nanocrystal product obtained in this invention depends on the selected parameters of the centrifugation or filtration process, and is generally set at 1%-30%, typically 4%-25%. Of course, this product can also be further concentrated or dried as needed. The composite cellulose nanocrystal product containing selectively water-soluble molecules obtained in this invention also typically has a solid content of 1%-30%, and can be further concentrated or dried as needed, for example, by spray drying, to obtain a powder product.

[0057] In summary, the method for manufacturing cellulose nanocrystals of the present invention achieves low-cost, large-scale industrial production of cellulose nanocrystals using CNC machining, with extremely low acid consumption, ultra-high yield, and minimal environmental emissions. It completely overcomes the industrialization bottlenecks of traditional cellulose nanocrystal manufacturing methods, such as extremely high acid consumption, extremely low yield, severe environmental emissions, high equipment investment, and extremely high production costs.

[0058] Furthermore, surprisingly, in the method of the present invention, the specific cellulose micelles obtained, without the aforementioned degradation and exfoliation process (e.g., the aforementioned oxidation reaction), will remain in the supernatant during centrifugation without settling. With the aforementioned degradation and exfoliation process, the nanoparticles can settle out after centrifugation to obtain the product, thereby greatly simplifying the process.

[0059] As another objective of this invention, various materials and applications of cellulose nanocrystals produced by the method of this invention are also provided. The cellulose nanocrystals of this invention can be used directly as liquid products, or after spray drying or freeze-drying. These cellulose nanocrystal products can also be mixed with any other natural and synthetic polymers, inorganic and organic molecules, nanoparticles, conductive molecules, optical molecules, thermally conductive molecules, and materials including graphite, graphene, carbon nanotubes, nano-silicon, two-dimensional materials, semiconductor materials, MXene, MOFs (metal-organic frameworks), etc., to create composite material products.

[0060] The cellulose nanocrystal products of this invention, including composite materials composed of other molecules, can be widely used in various industrial fields, food and nutrition, medicine, biomedical materials, daily chemical and cosmetic products, chemical industry, high-end coatings, aerospace, automobiles and ships, new energy materials, building materials, packaging materials, image display and printing, 3D printing, aerogels, agricultural materials, optical materials, electronic materials and a range of other industries. Attached Figure Description

[0061] Figure 1: Transmission electron microscope image of sample A from Example 1

[0062] Figure 2: Rheological results of sample A in Example 1

[0063] Figure 3: Transmission electron micrograph of sample G from Example 7

[0064] Figure 4: Transmission electron micrograph of sample H from Example 8 Detailed Implementation

[0065] The preparation, properties, and functions of the cellulose nanocrystal CNC of the present invention can be demonstrated through the following embodiments. However, the content of the present invention is not limited to these embodiments.

[0066] The test methods described in this embodiment are as follows:

[0067] (1) Method for determining the particle size of composite micelle solution: For composite micelles formed by hydrolyzed cellulose and water-soluble molecules, or composite micelles formed by commercially available cellulose raw materials, the determination criterion is that the particle size of micelle solution with a weight percentage of more than 50% is less than 1000 nanometers in water. In actual testing, the following two methods can be used to achieve this.

[0068] (a) This method is suitable for composite micelles where the selectively water-soluble molecules are high-molecular-weight or viscous substances. The steps are as follows: Dilute the micelle solution to a concentration of 0.2%, disperse it thoroughly, transfer it to a centrifuge tube, and centrifuge at 5000 rpm for 15 min. Measure the dry weight of the sediment and the supernatant separately to obtain the weight percentage of micelle particles in the supernatant. Then, take the supernatant, disperse it evenly, and use a laser scattering instrument to determine the particle size distribution, thus determining that all particles in the supernatant of the micelle solution in water are less than 1000 nanometers in size.

[0069] (b) This method is suitable for composite micelles where the selective water-soluble molecules are water molecules themselves, water-soluble salts, or small molecules. The steps are as follows: Dilute the micelle solution to a concentration of 0.2%, disperse it thoroughly, transfer it to a centrifuge tube, and centrifuge at 500 rpm for 10 min. Measure the dry weight of the sediment and the supernatant to obtain the weight percentage of micelle particles in the supernatant. Then, take the supernatant, disperse it evenly, and use a laser scattering instrument to determine the particle size distribution, thus determining that all particles in the supernatant of the micelle solution are less than 1000 nm in size in water.

[0070] (2) Method for determining particle size distribution using laser scattering instrument: Dilute the sample with deionized water to 0.02% (w / v) or less, disperse it thoroughly, and then measure it using a Zetasizer Nano ZS (Malvem, England) instrument.

[0071] (3) Rheological measurement methods: The prepared liquid sample was measured at 25℃ using an Anton Paar MCR 302 rheometer with the vibration frequency set to 1Hz. The rheological curves of storage modulus (G') and loss modulus (G”) versus shear strain (γ) were measured. The time-dependent thixotropy was measured at 20℃ with an equilibrium time of 1 min and a shear rate of... From 0s -1 Rise to 60s -1 The shear rate continued to increase for 5 minutes, using a linear mode; then the shear rate... From the 60s -1 Drop to 0s -1 The shear rate continued to decrease for 5 minutes, using linear mode.

[0072] (4) Transmission electron microscopy method: The sample to be tested was diluted to 0.01 g / mL and dispersed. Then the sample was placed on a copper grid, dried at room temperature, and observed using a New Bio-TEM H-7500 transmission electron microscope at 120 kV to determine the morphology of the particles, such as particle length, particle diameter or width.

[0073] (5) Zeta potential measurement method: Dilute the sample with deionized water to 0.01% (w / v) and measure the Zeta potential using a Zetasizer ZS (Malvern, England) instrument.

[0074] (6) Determination of sodium carboxymethyl cellulose: Transfer 2 g (accurate to 0.0001 g) of sample to a 250 mL round-bottom flask. Add 75 mL of glacial acetic acid, then add a few glass beads, heat under reflux for 2 h, cool, and then transfer the mixture to a 150 mL beaker with a small amount of glacial acetic acid. Use potentiometric titration to titrate the sample solution with 0.1 mol / L perchloric acid titrant until the reaction endpoint, record the volume of titrant consumed, and calculate the mass fraction of sodium carboxymethyl cellulose in the sample.

[0075] Where R represents the mass fraction (%) of sodium carboxymethyl cellulose in the sample;

[0076] V represents the volume (mL) of perchloric acid titrant consumed by the sample;

[0077] M represents the concentration (mol / L) of the perchloric acid titrant;

[0078] F indicates that 1 mL of perchloric acid titrant (0.1 mol / L) is equivalent to 29.6 mg of sodium carboxymethyl cellulose, and W indicates the sample mass (g).

[0079] Example 1: The supernatant of the composite micelles was centrifuged, then oxidized and separated from the phase.

[0080] Softwood pulp was reacted thoroughly with 0.25% hydrochloric acid at 140°C to obtain hydrolyzed cellulose with a degree of polymerization of 151. 90% (dry weight) of the wet hydrolyzed cellulose was co-milled with 10% (dry weight) sodium carboxymethyl cellulose and diluted to a 1% concentration to form a composite micelle solution. Using the aforementioned particle size determination method (a), 97% by weight of the solution contained particles with a particle size less than 1000 nanometers.

[0081] The composite micelle solution was centrifuged at 5000 rpm for 15 minutes in a rotary centrifuge, resulting in a clear solid / liquid separation system. The supernatant was collected and transferred to a reaction vessel, heated to 95°C, and 15% by weight (relative to the total solids of the supernatant) of hydrogen peroxide was added to the system. The reaction was allowed to proceed for 4 hours, or until the pH of the system dropped below 4.5.

[0082] The supernatant system after the above reaction was centrifuged again, and surprisingly, almost all the substances were completely precipitated. After washing the precipitate with deionized water, centrifugation was performed to obtain the precipitate, which had a solid content of 4.6%. This precipitate was collected and labeled as sample A. The yield of sample A relative to the softwood pulp raw material was 85.1%.

[0083] Sample A was observed under a transmission electron microscope. The particles were all cellulose nanocrystals, mostly 100-300 nm in length and 5-20 nm in diameter. The zeta potential was measured to be -23.4 mV.

[0084] The transmission electron microscope image of sample A is shown in Figure 1.

[0085] The rheological results of sample A at a concentration of 2.6% are shown in Figure 2. As indicated by the storage modulus G' and viscous modulus G” in the figure, the cellulose nanocrystals exhibit certain gel properties. When the strain value is greatly increased, the gel structure disappears and transforms into viscous fluid properties.

[0086] Example 2: The supernatant of the composite micelles was centrifuged, followed by enzymatic hydrolysis, oxidation, and phase separation.

[0087] Hardwood pulp was reacted thoroughly with 0.5% hydrochloric acid at 125°C to obtain hydrolyzed cellulose with a degree of polymerization of 137. 90% (dry weight) of the wet hydrolyzed cellulose was co-milled with 10% (dry weight) sodium carboxymethyl cellulose and diluted to a 1% concentration to form a composite micelle solution. Using the aforementioned particle size determination method (a), 92% by weight of the solution contained particles with a particle size less than 1000 nanometers.

[0088] The composite micelle solution was centrifuged at 5000 rpm for 15 minutes in a rotary centrifuge, resulting in a clear solid / liquid separation system in the centrifuge tube. The supernatant was collected and transferred to a reaction vessel, heated to 70°C, and the pH was adjusted to 5.5. 1% by weight (relative to the total solids in the supernatant) of cellulase (liquid reagent, Sunson Bioenzyme) was added to the system, and the reaction was allowed to proceed for 3 hours. Subsequently, the system was heated to 95°C, and 10% by weight (relative to the total solids in the supernatant) of hydrogen peroxide was added, and the reaction was allowed to proceed for 2 hours, or until the pH of the system dropped below 4.5.

[0089] The supernatant system after the above reaction was centrifuged again, and surprisingly, almost all the substances were completely precipitated. After washing the precipitate with deionized water, centrifugation was performed to obtain the precipitate, which had a solid content of 6.9%. This precipitate was collected and labeled as Sample B. The yield of Sample B relative to the hardwood pulp raw material was 83.5%.

[0090] Sample B was observed under a transmission electron microscope. The particles were all cellulose nanocrystals, mostly 100-300 nm in length and 5-20 nm in diameter. The zeta potential was measured to be -23.2 mV.

[0091] Example 3: The supernatant of the composite micelles was centrifuged, then oxidized and separated from the phase.

[0092] Commercially available colloidal microcrystalline cellulose ZGcel 7569 dry powder was added to deionized water and dispersed into a 1% micelle suspension using a high-speed blender. According to the aforementioned method (a) for determining the particle size of the micelle solution, 79% by weight of the solution contained particles with a particle size of less than 1000 nanometers.

[0093] The micelle solution was centrifuged at 8000 rpm for 15 minutes in a rotary centrifuge, resulting in a clear solid / liquid separation system in the centrifuge tube. The supernatant was collected and transferred to a reaction vessel, heated to 95°C, and 15% by weight (relative to the total solids of the supernatant) of hydrogen peroxide was added to the system. The reaction was allowed to proceed for 4 hours, or until the pH of the system dropped below 4.5.

[0094] The supernatant system after the above reaction was centrifuged again, and surprisingly, almost all the substances were completely precipitated. After washing the precipitate with deionized water, centrifugation was performed to obtain the precipitate, which had a solid content of 4.9%. This precipitate was collected and labeled as sample C. The yield of sample C was 63.2% relative to commercially available colloidal microcrystalline cellulose raw material.

[0095] Sample C was observed under a transmission electron microscope. The particle size was cellulose nanocrystals, with a length of about 100-400 nanometers and a diameter of about 10-30 nanometers.

[0096] Example 4: Direct oxidation and phase separation of composite micelles

[0097] Hardwood pulp was reacted thoroughly in 0.5% hydrochloric acid at 127°C to obtain hydrolyzed cellulose with a degree of polymerization of 142. 95.5% (dry weight) of the hydrolyzed cellulose wet material was co-milled with 4.5% (dry weight) of sodium carboxymethyl cellulose and diluted to a 4% concentration to form a composite micelle solution. Using the aforementioned method (a) for determining the particle size of the micelle solution, the particle size of 95% by weight of this solution was less than 1000 nanometers.

[0098] Without centrifugation, the composite micelle solution was directly heated to 90-97℃, and hydrogen peroxide (15% by weight relative to the composite micelles, dry weight) was added for oxidation under strong shear stirring for 3 hours or until the pH value dropped below 4.5. Subsequently, the oxidized micelle solution was pre-centrifuged and filtered once in a tubular centrifuge at 18000 rpm. Some particles settled on the centrifuge drum or filter screen. During sampling, the trace amount of sediment closest to the drum was removed, and the remaining solid sediment was collected, yielding a product with a solid content of 8.1%, labeled as sample D1. The pre-filtered solution was then circulated and centrifuged in a second tubular centrifuge at 18000 rpm until all nanoparticles settled on the centrifuge drum or filter screen, yielding a product with a solid content of 25%, labeled as sample D2. The total yield of products D1 and D2 was 87% (much of which was due to physical losses during sample collection, such as material remaining on the tube wall).

[0099] Samples D1 and D2 were observed under a transmission electron microscope. Both were cellulose nanocrystals. The length of D1 was mostly about 100-500 nm and the diameter was about 10-30 nm. The length of D2 was mostly about 100-300 nm and the diameter was about 10-30 nm. The zeta potential was measured to be -25.5 mV.

[0100] Example 5: Direct oxidation and phase separation of composite micelles

[0101] Commercially available colloidal microcrystalline cellulose ZGcel 500B (containing microcrystalline cellulose and xanthan gum) dry powder was added to deionized water and dispersed into a 2% micelle suspension using a high-speed blender. According to the aforementioned method (a) for determining the particle size of the micelle solution, 62% by weight of the solution contained particles with a particle size of less than 1000 nanometers.

[0102] Without centrifugation, the above-mentioned composite micelle solution was directly heated to 90-97℃, and hydrogen peroxide (20% by weight relative to the composite micelles, dry weight) was added for oxidation under strong shear stirring conditions for 4 hours or until the reaction pH dropped below 4.5. Subsequently, the oxidized micelle solution was subjected to strong shear treatment using a high-speed blender, followed by centrifugation and filtration using a rotary centrifuge at 5000 rpm to obtain a product with a solid content of 5.4%, labeled as sample E, with a yield of 70.4%.

[0103] Sample E was observed under a transmission electron microscope. The particle size was found to be cellulose nanocrystals, with a length of about 100-400 nanometers and a diameter of about 10-30 nanometers.

[0104] Example 6: Direct oxidative degradation of water molecule micelles, followed by multi-stage centrifugal purification.

[0105] Hardwood pulp was reacted thoroughly at 140°C under 0.55% hydrochloric acid to obtain hydrolyzed cellulose with a degree of polymerization of 139. After repeated intense shearing and grinding at a solid content of 42% (where deionized water can be considered the selectively water-soluble molecule of this invention), it was diluted with water and stirred to form a cellulose aqueous micelle solution with a solid content of 4%. Using the aforementioned method (b) for determining the particle size of the micelle solution, 79% by weight of the solution had a particle size of less than 1000 nanometers.

[0106] Without centrifugation, the above micelle solution was directly heated to 90-97°C, and hydrogen peroxide (15% by weight relative to the micelle solution, dry weight) was added for oxidation under strong shear stirring for 4 hours or until the reaction pH dropped below 4.5. Subsequently, the oxidized solution was subjected to multi-stage and circulating centrifugation filtration using a tubular centrifuge, with sedimentation on the centrifuge drum or filter screen to obtain a product with a solids content of approximately 20%, labeled as sample F. The yield of product F was 89.9%.

[0107] Sample F was observed under a transmission electron microscope. The particles were all cellulose nanocrystals, mostly 100-400 nm in length and 10-30 nm in diameter. The measured zeta potential was -23.6 mV.

[0108] Example 7: Water molecule micelle solution was degraded by strong mechanical force and selectively purified by centrifugation.

[0109] Hardwood pulp was reacted thoroughly in 0.55% hydrochloric acid at 140°C to obtain hydrolyzed cellulose with a degree of polymerization of 139. After repeated intense shearing and grinding at 42% solids content (where deionized water can be considered the selectively water-soluble molecule of this invention), the mixture was diluted to a dispersion with a 12% solids content. This dispersion was then subjected to intense shearing and beating in a high-speed blender for 15 minutes to form a paste-like micelle solution, which was further diluted to a water-soluble micelle solution with a 2% solids content. Using the aforementioned method (b) for determining the particle size of the micelle solution, 85% by weight of the solution contained particles with a particle size less than 1000 nanometers.

[0110] The 2% solids content aqueous micelle solution was then homogenized under high pressure at 80 MPa. Subsequently, the homogenized solution was subjected to multi-stage and circulating centrifugation filtration at 18000 rpm using a tubular centrifuge. Sedimentation was performed on the centrifuge drum or filter screen as a purification step. A trace amount of sediment closest to the drum (containing a small amount of coarse particles) was removed during sampling, and the remaining purified sediment solids were collected, yielding a product with a solids content of 12%, labeled as sample G. The yield of product G was 94.7%.

[0111] Sample G was observed under a transmission electron microscope. The particles were all cellulose nanocrystals, mostly 100-300 nm in length and 10-30 nm in diameter. The measured zeta potential was -23.1 mV.

[0112] The transmission electron microscope image of sample G is shown in Figure 3.

[0113] Example 8: The supernatant separated from the composite micelle solution was directly concentrated or dried to obtain a cellulose nanocrystal composite product containing sodium carboxymethyl cellulose molecules.

[0114] Hardwood pulp was reacted thoroughly in 0.5% hydrochloric acid at 140°C to obtain hydrolyzed cellulose with a degree of polymerization of 129. 88% (dry weight) of the wet hydrolyzed cellulose was co-milled with 12% (dry weight) of sodium carboxymethyl cellulose and diluted to a 0.5% concentration to form a composite micelle solution. Using the aforementioned method (a) for determining the particle size of the micelle solution, 97% by weight of the solution had a particle size less than 1000 nanometers.

[0115] The composite micelle solution was centrifuged at 5000 rpm for 15 minutes in a rotary centrifuge, resulting in a clear solid / liquid separation. The supernatant was collected and concentrated by rotary evaporation to a 5% solids content (this product contains sodium carboxymethyl cellulose), with a yield of 91%. This product can be used as the final product or spray-dried to obtain a dry powder composite product containing cellulose and water-soluble molecules, labeled as sample H.

[0116] Sample H was observed under a transmission electron microscope. The particle size was found to be cellulose nanocrystals, mostly with a length of about 100-300 nm and a diameter of about 10-40 nm. The zeta potential was measured to be -58.7 mV, and the sodium carboxymethyl cellulose content in this composite product was determined to be 12.5%.

[0117] The transmission electron microscope image of sample H is shown in Figure 4.

[0118] Example 9: Water molecule micelle solution degraded by a combination of acid hydrolysis and strong mechanical force

[0119] Hardwood pulp was reacted thoroughly in 0.55% hydrochloric acid at 140°C to obtain hydrolyzed cellulose with a degree of polymerization of 139. After repeated intense shearing and grinding at a solid content of 42% (where deionized water can be considered the selectively water-soluble molecule of this invention), it was diluted with deionized water to a solid content of 20%, and then subjected to degradation again in 0.25% hydrochloric acid at 125°C. The resulting product was then centrifuged and filtered to obtain cellulose micelles. This micelle dispersion was tested using the aforementioned method (b) for determining the particle size of the micelle feed solution; 81% by weight of the feed solution had a particle size less than 1000 nanometers.

[0120] The cellulose micelles obtained from the centrifugation and filtration process were subjected to repeated intense shearing and grinding at a solid content of 39% to obtain Product I, with a yield of 89.1%. Product I was observed under a transmission electron microscope to be composed entirely of cellulose nanocrystals, with lengths mostly around 100-400 nanometers and diameters around 10-30 nanometers.

[0121] Example 10: Comparative Example of Substandard Composite Micellar Liquid

[0122] Softwood pulp was reacted with 0.15% hydrochloric acid at 125°C for 10 minutes to obtain hydrolyzed cellulose with a degree of polymerization of 344. 90% (dry weight) of the wet hydrolyzed cellulose was co-milled with 10% (dry weight) sodium carboxymethyl cellulose and diluted to a 1% concentration to form a composite micelle solution. Using the aforementioned method (a) for determining the particle size of the micelle solution, 34% by weight of the solution had a particle size less than 1000 nanometers. This solution does not meet the standard for hydrolyzed cellulose required by this invention.

[0123] (1) The supernatant from centrifugation does not oxidize (cellulose nanocrystal composite product containing sodium carboxymethyl cellulose):

[0124] The composite micelle solution was centrifuged at 5000 rpm for 15 minutes in a rotary centrifuge, resulting in a clear solid / liquid separation. The supernatant was collected and concentrated by rotary evaporation to a product with a solid content of 5% (this product contains sodium carboxymethyl cellulose), yielding a product yield of 31%. Clearly, this yield does not meet the requirements of the high-yield, low-cost method of this invention.

[0125] (2) Oxidation of centrifuged supernatant:

[0126] The composite micelle solution was centrifuged at 5000 rpm for 15 minutes in a rotary centrifuge, resulting in a clear solid / liquid separation system. The supernatant was collected and transferred to a reaction vessel, heated to 95°C, and 15% by weight (relative to the total solids of the supernatant) of hydrogen peroxide was added to the system. The reaction was allowed to proceed for 4 hours, or until the pH of the system dropped below 4.5.

[0127] The supernatant system after the above reaction was centrifuged again, and almost all the substances completely precipitated. The precipitate was washed with deionized water and then centrifuged again to obtain the precipitate. This precipitate was collected to obtain a sample, the yield of which was 25% relative to the softwood pulp raw material. Clearly, this yield is far from meeting the requirements of the high-yield, low-cost method of this invention.

[0128] (3) Direct oxidation without centrifugation:

[0129] Without centrifugation, the above-mentioned composite micelle solution was directly heated to 90-97°C, and hydrogen peroxide (15% by weight relative to the composite micelles, dry weight) was added for oxidation under strong shear stirring conditions for 4 hours or until the reaction pH dropped below 4.5. Subsequently, the oxidized micelle solution was centrifuged and filtered at 5000 rpm using a rotary centrifuge, yielding a large amount of precipitate. This sample contained a large number of particles larger than 1000 nanometers or micrometers, and therefore could not yield the nanocrystalline product of this invention.

Claims

1. A method for producing cellulose nanocrystals, characterized in that... The method includes the step of preparing a cellulose micelle dispersion by combining cellulose raw materials and selective water-soluble molecules, wherein the cellulose micelles constitute more than 50% by weight and have a particle size of less than 1000 nanometers in water; preferably, the cellulose micelles constitute more than 70% by weight and have a particle size of less than 1000 nanometers in water; preferably, the cellulose micelles constitute more than 90% by weight and have a particle size of less than 1000 nanometers in water; preferably, the cellulose micelles constitute more than 97% by weight and have a particle size of less than 1000 nanometers in water.

2. The method according to claim 1, wherein the cellulose raw material is hydrolyzed cellulose or commercially available cellulose.

3. The method according to claim 2, wherein the degree of polymerization of the hydrolyzed cellulose is controlled at 50-300 glucose units, preferably 100-250 glucose units.

4. The method according to claims 2-3, wherein the hydrolyzed cellulose is obtained from plant cellulose of any source by low-acid hydrolysis; preferably, hydrolyzed cellulose is prepared by using a diluted inorganic acid hydrolysis method; preferably, the acid concentration is 0.1%-10%; preferably, it is dilute hydrochloric acid, dilute sulfuric acid, dilute nitric acid, etc. with a concentration of 0.1%-1%.

5. The method according to claim 2, wherein the commercially available cellulose is selected from microcrystalline cellulose plus sodium carboxymethyl cellulose composite colloid, microcrystalline cellulose plus xanthan gum composite colloid, microcrystalline cellulose plus sodium alginate composite colloid, microcrystalline cellulose plus carrageenan composite colloid, microcrystalline cellulose plus pectin composite colloid, microcrystalline cellulose plus guar gum composite colloid, microcrystalline cellulose plus modified starch composite colloid, etc.

6. The method according to claims 1-5, wherein the selectively water-soluble molecules are selected from: carboxymethyl cellulose and its salts; water-soluble cellulose ethers such as hydroxypropyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, etc.; natural water-soluble colloid molecules such as starch, sodium alginate, pectin, carrageenan, xanthan gum, chitosan, water-soluble plant protein, water-soluble animal protein, etc.; synthetic polymers such as polyvinyl alcohol, polyethylene glycol, povidone (polyvinylpyrrolidone), copovidone, poloxamer (polyoxyethylene polyoxypropylene ether block copolymer), carbomer (polyacrylic acid), polyacrylamide, polyethyleneimine, polyethyleneamine, etc.; water-soluble salts such as sodium chloride, potassium chloride, lithium chloride, calcium chloride, magnesium chloride, aluminum chloride, ammonium chloride, zinc chloride, ferric chloride, copper chloride, zirconium chloride, sodium carbonate, zirconium carbonate, magnesium sulfate, aluminum sulfate, copper sulfate, ferric sulfate, zirconium sulfate, organic quaternary ammonium salts, etc.; and water molecules themselves such as liquid water and solid ice.

7. The method according to claims 1-6, comprising the following steps: (1) The cellulose micelle dispersion is prepared by co-milling and / or forcefully shearing cellulose raw materials and selective water-soluble molecules; (2) Remove particles with a particle size greater than and / or equal to 1000 nm from the cellulose micelle dispersion prepared in step (1) by centrifugation or filtration to obtain a centrifuged supernatant or filtrate with a particle size less than 1000 nm. (3) The supernatant or filtrate obtained in step (2) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation is carried out by oxidation reaction using hydrogen peroxide; (4) The hydrolyzed cellulose nanoparticle suspension obtained in step (3) is centrifuged or filtered to obtain a concentrated solution or wet cake of cellulose nanocrystals, thus obtaining the cellulose nanocrystal product.

8. The method according to claims 1-6, comprising the following steps: (1) The cellulose micelle dispersion is prepared by co-milling and / or forcefully shearing cellulose raw materials and selective water-soluble molecules; (2) Remove particles with a particle size greater than and / or equal to 1000 nm from the cellulose micelle dispersion prepared in step (1) by centrifugation or filtration to obtain a centrifuged supernatant or filtrate with a particle size less than 1000 nm. (3) The centrifuged supernatant or filtrate obtained in step (2) is concentrated or dried to obtain a composite cellulose nanocrystal product containing selective water-soluble molecules.

9. The method according to claims 1-6, comprising the following steps: (1) The cellulose micelle dispersion is prepared by co-milling and / or forcefully shearing cellulose raw materials and selective water-soluble molecules; (2) The cellulose micelle dispersion obtained in step (1) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation are selected from any one or a combination of oxidation, enzymatic hydrolysis, acid degradation, alkaline degradation, microbial degradation, and ultra-strong shear mechanical degradation; more preferably, the degradation and exfoliation are carried out by oxidation reaction using hydrogen peroxide; (3) The hydrolyzed cellulose nanoparticle suspension obtained in step (2) is centrifuged or filtered to obtain a concentrated solution or wet cake of cellulose nanocrystals, thus obtaining the cellulose nanocrystal product.

10. The method according to claims 1-6, comprising the following steps: (1) The cellulose raw material is co-milled and / or subjected to strong shearing with water molecules or water-soluble salts to prepare the cellulose micelle dispersion; (2) The cellulose micelle dispersion obtained in step (1) is degraded and exfoliated to obtain a suspension of hydrolyzed cellulose nanoparticles; preferably, the degradation and exfoliation are selected from any one or a combination of oxidation, enzymatic hydrolysis, acid degradation, alkaline degradation, microbial degradation, and ultra-strong shear mechanical degradation; more preferably, the degradation and exfoliation are performed using an ultra-strong shear mechanical degradation and exfoliation method; most preferably, the degradation and exfoliation are performed using high-pressure homogenization; (3) Centrifuge or filter the hydrolyzed cellulose nanoparticle suspension obtained in step (2) to obtain a concentrated solution or wet cake of cellulose nanocrystals, and obtain cellulose nanocrystal products.

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