Method for producing a nanodispersion of nanocellulose in a liquid medium

Abstract

There is provided a method for producing a nanodispersion of nanocellulose in a first liquid medium, the method comprising providing a nanodispersion of the nanocellulose in water, and while stirring, gradually adding said first liquid medium or one or more components thereof to the nanodispersion, thereby nanodispersing the nanocellulose in said first liquid medium. There is also provided method for producing a nanodispersion of cellulose nanocrystals in a second liquid medium starting from a nanodispersion of the cellulose nanocrystals in a first liquid medium, the method comprising providing said nanodispersion of the cellulose nanocrystals in the first liquid medium, and while stirring, gradually adding said second liquid medium or one or more components thereof to the nanodispersion of the cellulose nanocrystals in the first liquid medium, thereby nanodispersing the cellulose nanocrystals in said second liquid medium, wherein the first liquid medium is miscible with the second liquid medium.

Description

METHOD FOR PRODUCING A NANODISPERSION OF NANOCELLULOSE IN A LIQUID MEDIUMCROSS REFERENCE TO RELATED APPLICATIONSThis application claims benefit, under 35 U.S.C. § 119(e), of U.S. provisional applications Serial No. 63 / 557,881 , filed on February 26, 2024, and Serial No. 63 / 645,246, filed on May 10, 2024. All documents above are incorporated herein in their entirety by reference.FIELD OF THE INVENTION

[0001] The present invention relates to a method for producing a nanodispersion of nanocellulose in a liquid medium. More specifically, the present invention is concerned with a method for producing a nanodispersion of nanocellulose in a liquid medium that provide a better dispersion in many liquid media.BACKGROUND OF THE INVENTION

[0002] Cellulose nanocrystals (CNCs), also called nanocrystalline cellulose or crystalline nanocellulose, as well as cellulose nanofibrils (CNF) are known in the art.

[0003] Cellulose is a hydrophilic semi-crystalline polysaccharide. Cellulose is naturally organized into long linear chains of ether-linked poly([3-1 ,4-glucopyranose) units. These chains assemble by intra- and inter-molecular hydrogen bonds into highly crystalline domains - see Fig. 1 . Regions of disordered (amorphous) cellulose exist between these crystalline domains (nanocrystals) in the cellulose nanofibrils. Extensive hydrogen bonding among the cellulose polymer chains makes cellulose extremely resistant to dissolution in water and most organic solvents, and even many types of acids.

[0004] As shown in Figure 1 , cellulose fibers are made of fibrils. Those fibrils are basically bundles of nanofibrils, each nanofibril, also called cellulose nanofibers (CNF), containing crystalline cellulose domains separated by amorphous cellulose domains. These crystalline cellulose domains can be liberated by removing the amorphous cellulose domains, which yields cellulose nanocrystals (CNC). CNCs are thus rodlike highly crystalline particles. Collectively, CNFs and CNCs are referred to as “nanocellulose”.

[0005] Various methods of producing CNCs are known. In a conventional method, CNCs are formed by acid hydrolysis of native cellulose fibers commonly using sulfuric acid (which introduces SO3~ surface groups). Amorphous sections of native cellulose are thus hydrolysed and the crystalline sections (i.e., the CNCs) are retrieved. Another method of producing CNCs is described in WO2016015148A1 , incorporated herein by reference. This method uses a peroxide together with heat and / or UV to both hydrolyze and oxidize the cellulose. This method produces CNCs with surface carboxylic acid (COO ) groups or salts thereof.

[0006] CNFs can also be manufactured in different ways. High-pressure homogenization involves passing acellulose suspension through a narrow gap at high pressure, which breaks down the fibers into nanofibers. Microfluidization is similar to homogenization since it uses high-pressure fluid streams to shear the cellulose fibers into nanofibers. Mechanical grinding can also be used to break down cellulose fibers into nanofibers. Before mechanical processing, cellulose fibers can be chemically treated to weaken the bonds between them. This makes the mechanical disintegration process more efficient. Alternatively, enzymes can also be used to partially break down the cellulose fibers, making it easier to produce nanofibers through mechanical methods.

[0007] One of the main limitations of using CNCs and CNFs in industrial applications is that in order to gain the optimum benefits of these nanocelluloses, they must be very well dispersed in the system they are to be used in. The ability of CNCs / CNFs to fully disperse at the nanoscale, without the need for surface modifications, requires adding them in a pre-dispersed aqueous form. Indeed, CNCs / CNFs can be relatively easily dispersed in water. However, many industrial applications cannot handle high amounts of water in whatever liquid medium they use, and the chemicals used (such as solvents, monomers, surfactants, salts, etc.) can cause rapid agglomeration of CNCs / CNFs due to incompatibility.

[0008] Agglomeration can be caused by:• Chemical incompatibility - an example would be trying to disperse nanocellulose in solvents with low polarity, which causes CNCs to aggregate through hydrogen bond formation.• High ionic strength - The nanocellulose ability to form stable dispersions of individual CNCs or CNFs in water is controlled by the surface charge, which is often negative as a result of the manufacturing processes (which introduces -COO', -SOa' surface groups). When the ionic strength increases, agglomeration can occur through screening of this negative charge, which decreases the electrostatic repulsion between individual crystals.• pH - nanocellulose can be highly sensitive to pH, particularly when the anionic stabilization of the particles is due to weak acid groups on the surface, such as carboxylates (COO ). Decreasing pH leads to protonation of the acid and can significantly reduce the charge on the surface, leading to rapid agglomeration.

[0009] To get around this agglomeration, there are a few methods that are commonly used.• Surface modification of the nanocellulose to enhance compatibility. This is often done to prepare less hydrophilic CNCs or CNFs or add functional groups similar in nature to the system they will be dispersed in, to make them less likely to agglomerate in anhydrous systems. This adds cost to the production of the nanocellulose , and dispersion in the anhydrous system typically still requires high energy techniques for optimal dispersion.• Dilute the nanocellulose or add additional water to the system. This is often not desired as it requires either lowering the solids content of the final system. Additionally, for systems that normally would not have water, minimizing the amount added is often crucial for industrial viability, such as for use in condensation polymerization reactions. In some cases, water can be removed after the dispersion is prepared, but this ishighly energy intensive, so minimize the water in the initial mix is necessary for commercial viability.• Use sonication or other high energy dispersion technique. This is one of the most common methods in academia especially, but it is often not possible at industrial scales due to cost of implementation and other process limitations. If aggregates of nanocellulose have already formed in the system, these techniques are often not able to fully redisperse them.• Freeze drying and spray drying. Some use freeze drying to produce a powder of CNC or CNF and then add this powder to the system they are studying. With or without the use of sonication or other dispersion techniques, these dry forms of nanocellulose are typically only fully dispersible in water. The effectiveness of this technique, combined with sonication, is limited / poor in terms of full nanodispersion of individual crystals in the matrix, and often only yields minor improvements unless pre-dispersed first in water alone.

[0010] Turning now to another topic, semicrystalline biodegradable polymers, such as polylactide (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), and polyhydroxy alkanoates (PHA’s) are currently being adopted for various applications as sustainable replacements for non-biodegradable petroleum-based plastics that are currently widely used, but slowly phased out of an increasing number of applications due to regulation and / or consumer pressure. However, the applications of biodegradable polymers are limited by both the properties of the final products (mechanical / barrier performance), and the ability to rapidly process them using existing equipment. One significant barrier to the widespread adoption of these polymers is their crystallization properties, such as crystallization temperature and rate, which can make their processability and control of properties challenging. Typically, nucleating agents are used for semicrystalline polymers to increase the crystallization temperature and / or speed, which can also increase the mechanical and barrier properties of the plastics. Because the market for most biodegradable polymers is relatively new and their structure is quite different from traditional polymers, the number of nucleating agents available for these types of markets is limited.

[0011] Currently, there are a few known nucleating agents for use in PLA and some PHA’s, which are notorious for being particularly slow to crystallize, but to the best of our knowledge, there are no common commercial nucleating agents for polymers such as PBAT and PBS, which crystallize at relatively low temperatures. Especially when making molded parts or fibers, slow or low temperature crystallization can significantly increase the time for which the polymer remains sticky during processing, increasing cycle times of production, driving costs up, and limiting the potential applications. This is of particular importance for single-use plastics that are difficult to recycle, such as those used in food-based applications (packaging, utensils, etc.)

[0012] It has been found that nanocellulose can act as nucleating agents for a variety of polymers, including, but not limited to, biodegradable polymers such as PLA, PBAT, PBS, polybutylene succinate adipate (PBSA), polybutylene succinate adipate terephthalate (PBSAT), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), and other polyhydroxyalkanoates (PHA’s). While CNCs / CNFs has been known to have a nucleating effect in these polymers, incorporating them in the polymer matrix through commercially viable methods has been a challenge. Typical methods for incorporating nanocellulose in polymers include 1) solvent casting, where large amounts ofsolvent are used to fully dissolve the polymer, and leads to partial agglomeration of CNCs / CNFs, 2) surface modification of CNCs / CNFs to improve compatibility with the polymer matrix, also still in a partially agglomerated form, and 3) compounding of dry forms of nanocellulose , or nanocellulose in water alone, which leads to a polymer containing primarily large agglomerates of nanocellulose with minimal benefits.SUMMARY OF THE INVENTION

[0013] In accordance with the present invention, there is provided:1. A method for producing a nanodispersion of nanocellulose in a first liquid medium, the method comprising:A) providing a nanodispersion of the nanocellulose in water, andB) while stirring, gradually adding said first liquid medium or one or more components thereof to the nanodispersion of the nanocellulose in water, thereby nanodispersing the nanocellulose in said first liquid medium, wherein the first liquid medium a liquid other than pure water and is miscible with water.2. The method of embodiment 1, wherein the nanodispersion of the nanocellulose in water provided at step A) is a commercially available CNCs nanodispersion in water, such as that available under the tradename “DextraCel® HS” sold by Anomera® Inc.3. The method of embodiment 1 , wherein step A) comprises nanodispersing dried nanocellulose, preferably dried cellulose nanocrystals, more preferably dried CNCs available under the tradename “DextraCel® HP” sold by Anomera® Inc., in water.4. The method of any one of embodiments 1 to 3, wherein the nanocellulose is nanodispersed in deionized or demineralized water.5. The method of any one of embodiments 1 to 4, wherein the nanodispersion of the nanocellulose in water provided at step A) has a nanocellulose concentration of up to about 5 wt / wt%, preferably up to about 8 wt / wt%, more preferably up to about 10 wt / wt%, and most preferably up to about 15 wt / wt%, based on the total weight of the nanodispersion.6. The method of any one of embodiments 1 to 5, further comprising step C) of removing water from the nanodispersion produced at step B).7. The method of embodiment 6, wherein step C) is carried by heating above 100°C while mixing or by using a vacuum (e.g. a rotary evaporator) to lower a required temperature for removal, and heating at said temperature for removal.8. The method of any one of embodiments 1 to 7, further comprising step D) of producing a nanodispersion of nanocellulose in a second liquid medium using the nanodispersion of nanocellulose in the first liquid medium.9. The method of embodiment 8, wherein step D) comprises, while stirring, gradually adding said second liquid medium or one or more components thereof to the nanodispersion of the nanocellulose in the first liquid medium, thereby nanodispersing the nanocellulose in said second liquid medium, wherein the second liquid medium is miscible with the first liquid medium.10. The method of embodiment 9, wherein the first liquid medium is a carrying liquid miscible with both water and the second liquid medium, wherein the second liquid medium is immiscible with water.11 . The method of embodiment 9 or 10, wherein the first liquid medium is butanediol, ethyl lactate, or melted polyethylene glycol (PEG) and is a carrying liquid used to achieve nanodispersion in a melted polymer that is immiscible with water, such as polylactide (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), or polyhydroxyalkanoates (PHA’s).12. The method of any one of embodiments 1 to 11 , further comprising step E) of removing the first liquid medium from the nanodispersion produced at step D).13. The method of any one of embodiments 1 to 12, further comprising step F) of repeating step D) or step D) followed by step E) one or more times, each time producing a nanodispersion of nanocellulose in a further liquid medium using a nanodispersion of nanocellulose produced during the immediately preceding step D), wherein each further liquid medium is miscible with the liquid medium of the nanodispersion of nanocellulose produced during the immediately preceding step D).14. A method for producing a nanodispersion of cellulose nanocrystals in a second liquid medium starting from a nanodispersion of the cellulose nanocrystals in a first liquid medium, the method comprising: i) providing said nanodispersion of the cellulose nanocrystals in the first liquid medium, wherein the first liquid medium is a liquid other than water, and ii) while stirring, gradually adding said second liquid medium or one or more components thereof to the nanodispersion of the cellulose nanocrystals in the first liquid medium, thereby nanodispersing the cellulose nanocrystals in said second liquid medium, wherein the first liquid medium is miscible with the second liquid medium.15. The method of embodiment 14, further comprising step Hi) of removing said first liquid medium from the nanodispersion produced at step ii).16. The method of embodiment 14 or 15, further comprising step iv) of repeating step ii or step ii followed by step Hi one or more times, each time producing a nanodispersion of nanocellulose in a further liquid medium using a nanodispersion of nanocellulose produced during the immediately preceding step ii), wherein each further liquid medium is miscible with the liquid medium of the nanodispersion of nanocellulose produced during the immediately preceding step ii).17. The method of any one of embodiments 1 to 16, wherein the nanodispersion of nanocellulose in the firstliquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium is: an aqueous solution, dispersion, or suspension of a charge in water or in a non-aqueous liquid; a non-aqueous liquid including: a solvent, such as methanol, ethanol, dimethylformamide, dimethyl sulfoxide, acrylonitrile, acetone, tetrahydrofuran, 1,4-dioxane, ethyl lactate, or glycerol, a melted polymer, composite, or biocomposite polymer, of a carrying liquid, such as a melted solid; a liquid industrial formulation aqueous and non-aqueous); or a liquid reactant (aqueous and non-aqueous), such as a liquid monomer e.g. for condensation polymerization.18. The method of embodiment 17, wherein the carrying liquid is ethyl lactate, butanediol, glycerol, dimethylformamide, dimethylsulfoxide, ethylene glycol, or melted polyethylene glycol.19. The method of embodiment 17 or 18, wherein the melted polymer is polylactide (PLA), polybutylene adipate terephthalate (PBAT), polyethylene terephlalate (PET), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polylactate-co-hydracrylate (PLH), or polyhydroxyalkanoates (PHA’s).20. The method of any one of embodiments 17 to 19, wherein the liquid industrial formulation is a solution, dispersion, or suspension of a charge in a solvent e.g. water or a non-aqueous liquid.21 . The method of any one of embodiments 17 to 20, wherein the liquid industrial formulation is: a coating such as: a paint, primer, or topcoat; a protective coating, such as a coating offering protection against corrosion, UV, scratches, fingerprints, glare, smudge, or weather; an insulating coating; an easy-to-clean coating; a low-reflection or anti-reflection coating; or a lubricant or friction reduction coating, a sealant, or an adhesive, such as a pressure sensitive adhesive, or an epoxy.22. The method of any one of embodiments 17 or 21, wherein the liquid reactant is a monomer, such as amonomer for a polymerization reaction, for example condensation polymerization.23. The method of embodiment 22, wherein the monomer is ethylene glycol, 1 ,4-butandiol (BDO), a mixture of adipic acid, 1 ,4-butanediol and terephthalic acid, a mixture of 1 ,4-butanediol and succinic acid, or lactic acid24. The method of any one of embodiments 1 to 23, wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium has a cellulose nanocellulose of up to about 15 wt / wt%, preferably up to about 10 wt / wt%, and more preferably up to about 5 wt / wt%, based on the total weight of the nanodispersion.25. The method of any one of embodiments 1 to 24, wherein the nanocellulose bear surface groups such as carboxylate ions and / or sulfate ions.26. The method of any one of embodiments 1 to 25, wherein the nanocellulose bear surface carboxylate ions.27. The method of any one of embodiments 1 to 26, wherein the nanocellulose is cellulose nanocrystals or cellulose nanofibrils, preferably cellulose nanocrystals.28. The method of embodiment 17, wherein the cellulose nanocrystals are from about 2 to about 20 nm in diameter and from about 80 to about 400 nm in length, preferably from about 5 to about 10 nm in diameter and from about 100 to about 250 nm in length.29. The method of embodiment 17 or 18, wherein the cellulose nanofibrils are from about 5 to about 100 nm with an aspect ratio > about 30, preferably from about 5 to about 50 nm in diameter and an aspect ratio > about 50.30. The method of any one of embodiments 1 to 29, wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium is substantially free of agglomerated nanocellulose.31 . The method of embodiment 30, wherein the agglomerated nanocellulose is greater than 1000 nm in width and 1000 in length, preferably greater than 500 nm in width and 1000 nm in length, and more preferably greater than 400 nm in in width and 400 nm in length.32. The method of embodiment 30 or 31 , wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium comprises less than 10 wt / wt% of the agglomerated nanocellulose, preferably less than 5 wt / wt%, preferably less than 1 wt / wt%, based on the total weight to the nanocellulose.33. The method of any one of embodiments 30 to 32, wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium is free of agglomerated nanocellulose.34. The method of any one of embodiments 1 to 33, wherein the adding at step B), D), F), ii) and / or iv) lasts at least 5 minutes, preferably at least 10 minutes, and more preferably at least 15 minutes.35. The method of any one of embodiments 1 to 34, wherein an addition rate at step B), D), F), ii) and / or iv) is at most 20% per minute, preferably at most 10% per minute, and most preferably at most 5% per minute.36. The method of any one of embodiments 1 to 35, wherein the adding at step B), D), F), ii) and / or iv) is carried out by spraying droplets, or by adding dropwise.37. The method of any one of embodiments 1 to 36, wherein the adding at step B), D), F), ii) and / or iv) is carried out gradually, thereby producing a mixture, until the viscosity of the mixture has risen and then started to decrease, then the rest of the adding is carried out at once.38. The method of embodiment 36, wherein the adding at step B), D), F), ii) and / or iv) is carried out at such a rate that a decrease in viscosity is observed at least 5 minutes, preferably at least 10 minutes, and more preferably at least 15 minutes after said adding has started.39. The method of any one of embodiments 1 to 38, wherein the stirring is carried out at 150-300 rpm, preferably using a paddle- or anchor-type impeller.40. The method of any one of embodiments 1 to 39, wherein the first liquid medium is:Liquid Medium A: an aqueous solution, dispersion, or suspension of a charge in water, orLiquid Medium B: a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a non-aqueous liquid, wherein Liquid Medium A and Liquid Medium B are both miscible with water.41 . The method of any one of embodiments 8 to 39, wherein the second liquid medium is:Liquid Medium A: an aqueous solution, dispersion, or suspension of a charge in water, orLiquid Medium B: a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a non-aqueous liquid, wherein Liquid Medium A and Liquid Medium B are both miscible with the first liquid medium.42. The method of any one of embodiments 13 to 39, wherein the further liquid medium is:Liquid Medium A: an aqueous solution, dispersion, or suspension of a charge in water, orLiquid Medium B: a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a non-aqueous liquid, wherein Liquid Medium A and Liquid Medium B are both miscible with a liquid medium of a nanodispersion of nanocellulose produced during the immediately preceding step D) or ii).43. The method of any one of embodiments 40 to 42, wherein the first liquid medium in step B), or the secondliquid medium in step D) or ii) , or the further liquid medium in step F) or iv) is Liquid Medium A. The method of embodiment 43, where the adding at step B), D), F), ii) and / or iv) comprises : a) adding part of or all of (preferably all of) the water of the Liquid Medium A and stirring, thereby producing a mixture, and b) while stirring, after step b), gradually adding the charge of the Liquid Medium A to the mixture produced at a), wherein the adding at step b) lasts at least 5 minutes. The method of embodiment 44, wherein during step a), the water is added all at once. The method of embodiment 44 or 45, wherein during step b), a viscosity of a mixture to which the charge of the Liquid Medium A is added, increases and then start decreasing, and wherein the adding of the charge of the Liquid Medium A is carried out gradually, until said viscosity start decreasing, then any remaining charge of the Liquid Medium A is added at once or at any other addition rate. The method of any one of embodiments 43 to 46, wherein the adding at step B), D), F), ii) and / or iv) is carried out in a formulation vessel, and comprises:1 ) adding part of or all of (preferably all of) the water of the Liquid Medium A to the formulation vessel and stirring, thereby producing a mixture of nanocellulose in water,2) while stirring, gradually adding the charge of Liquid Medium A to the formulation vessel until the viscosity of the mixture has risen and then started to decrease, thereby producing a viscous mixture, and3’) storing the viscous mixture for future use, and / or3”) adding any remaining charge of the Liquid Medium A to the formulation vessel, wherein the adding at step 2) lasts at least 5 minutes. The method of any one of embodiments 43 to 47, wherein the Liquid Medium A is a waterborne industrial product, such as: a waterborne coating, for example : a paint, primer, or topcoat; a protective coating (e.g., offering protection against corrosion, UV, scratches, fingerprints, glare, smudge, or weather); an insulating coating; an easy-to-clean coating; a low-reflection or anti-reflection coating, ora waterborne lubricant or a friction reduction coating, a waterborne sealant, or a waterborne adhesive (e.g. a waterborne epoxy).49. The method of any one of embodiments 43 to 48, wherein the Liquid Medium A is a polyurethane dispersion (PUDs), a polyacrylate (PAC) dispersion, a polyurethane / polyacrylate (PU / PAC) hybrid dispersion, a polyester / polyacrylate (PES / PAC) dispersion, a polyisocyanate dispersion, an alkyd dispersion, a polyvinyl alcohol (PVA) dispersion, an epoxy dispersion, a polyol dispersion, a dispersion of copolymers thereof, or a mixture thereof; all of which being a one-component (1 K) and two-component (2K) system; all of which optionally comprising crosslinker(s), catalyst(s), cosolvent(s), etc.50. The method of any one of embodiments 43 to 49, wherein the Liquid Medium A has a conductivity (ionic strength) 1000 uS / cm, preferably 1200 uS / cm.51 . The method of any one of embodiments 43 to 50, wherein the Liquid Medium A is acidic.52. The method of any one of embodiments 43 to 51, wherein the Liquid Medium A has a pH of < 7.53. The method of any one of embodiments 43 to 52, wherein the Liquid Medium A has a pH of > 2.54. The method of any one of embodiments 43 to 53, wherein the Liquid Medium A is free of cationic surfactant.55. The method of any one of embodiments 43 to 54, wherein the Liquid Medium A comprises one or more nonionic and / or anionic surfactants.56. The method of any one of embodiments 40 to 42, wherein the first liquid medium in step B), or the second liquid medium in step D) or ii) , or the further liquid medium in step F) or iv) is Liquid Medium B.57. The method of embodiment 56, wherein, during the adding at step B), D), F), ii) and / or iv), the viscosity of a mixture to which the Liquid Medium B is gradually added first increases and then start decreasing, and wherein, when the viscosity starts decreasing, any remaining Liquid Medium B is added at once.58. The method of embodiment 56 or 57, wherein the adding at step B), D), F), ii) and / or iv) is carried out in a formulation vessel and comprises:1) while stirring, gradually adding the Liquid Medium B to the formulation vessel, until a mixture is produced and the viscosity of the mixture has risen and then started to decrease, thereby producing a viscous mixture, and2a) storing the viscous mixture for future use, or2b) adding any remaining Liquid Medium B to the formulation vessel, wherein the adding at step 1) lasts at least 5 minutes.59. The method of any one of embodiments 56 to 58, wherein the Liquid Medium B is:a carrying liquid such as polyethylene glycol or ethyl lactate; a non-aqueous water-miscible solvent such as methanol, ethanol, dimethylformamide, dimethyl sulfoxide, acrylonitrile, acetone, tetrahydrofuran, 1 ,4-dioxane, or glycerol; a monomer, e.g., for condensation polymerization, such ethylene glycol, 1,4-butandiol (BDO), a mixture of adipic acid, 1 ,4-butanediol and terephthalic acid, a mixture of 1 ,4-butanediol and succinic acid, or lactic acid; or a polymer, a composite, or a biocomposite polymer.BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In the appended drawings:FIG. 1 is a schematic representation of cellulose and its derivatives: cellulose CNFs and CNCs.FIG. 2 is a Transmission Electron Microscopy (TEM) micrograph showing the CNCs used in the Examples.FIG. 3 is a photograph (left) and a SEM micrograph (right) of CNCs agglomerated into a micro-powder.FIG. 4 shows the viscosity of WLS-213 containing 3 wt% DextraCel for samples with good dispersion (method of the invention) and poor dispersion (comparative method) at 50 rpm using a Brookfield viscometer. All solids content were adjusted to 32 wt% (from 35% for the resin) for consistency.FIG. 5 shows polarized optical microscope images with crossed linear polarizers following the addition of 3 wt% DextraCel to a formulation containing WLS-213 resin from DIC using (A) the method of the invention and (B) the conventional method.FIG 6 shows coated films (60 urn dry) of WLS-213 resin containing 3 wt% DextraCel: (A) good CNC dispersion obtained using the method of the invention and (B) poor CNC dispersion obtained using the conventional method.FIG. 7 shows images of BDO / DextraCel samples showing: (left) good dispersion prepared using the method of the invention and (right) poor dispersion obtained by the conventional method.FIG. 8 shows images of BDO / SA / DextraCel suspension showing (left) good dispersion prepared using the method of the invention and (right) poor dispersion obtained by the conventional method.Figure 9 shows polarized optical microscope images of 1 % DextraCel HS in BDO: (A and B) good dispersion using the method of the invention and (C and D) poor dispersion by adding DextraCel directly to BDO, with linear polarizers (A and C) not crossed and (B and D) crossed.Figure 10 shows polarized optical microscope images of 1 % DextraCel in BDO / SA: A and B) good dispersion using the method of the invention and (C and D) poor dispersion by adding DextraCel directly to BDO, with linear polarizers (A and C) not crossed and (B and D) crossed.Figure 11 is a plot of Brookfield’s viscosity for the method of the invention and the conventional method withincreasing shear (spindle speed).Figure 12 shows photographs of samples of DextraCel in (A) BDO and (B) BDO / SA prepared by the method of the invention after removal of water, viewed through a circular polarizer while illuminated by linearly polarized light.Figure 13 shows the FTIR spectra before and after water removal for samples containing (A) BDO and (B) BDO / SA.Figure 14 are optical microscope images of DextraCel in PBAT prepared (A) by adding PBAT to DextraCel in BDO (method of the invention) and (B) by adding DextraCel in BDO to PBAT (comparative) at a loading of 2 wt% based on solids.Figure 15 shows polarized optical microscope images of a 5% CNC in PEG composite mixture after melting, viewed with crossed linear polarizers to show birefringence.Figure 16 shows polarized optical microscope images of net PBS (left) and a 2% CNC in PBS composite mixture (right) after melting viewed with crossed linear polarizers to show birefringence.Figure 17 shows the normalized total enthalpy vs temperature measured by differential scanning calorimetry (DSC) for PBS composites at a cooling rate of 30 °C / min.Figure 18 shows polarized optical microscope images of a 2% CNC in PLA composite mixture after melting viewed with crossed linear polarizers to show birefringence.Figure 19 shows the isothermal DSC curve for PLA at a fixed temperature of 105 °C.Figure 20 shows polarized optical microscope images of a 2% CNC in PBAT composite mixture after melting viewed with crossed linear polarizers to show birefringence.Figure 21 shows the anisothermal DSC curve for PBAT composites at a cooling rate of 10 °C / min.Figure 22 shows polarized optical microscope images of melted PHBH polymer containing CNC was placed on a microscope slide viewed with crossed linear polarizers.Figure 23 showsDETAILED DESCRIPTION OF THE INVENTION

[0015] Turning now to the invention in more details, there is provided a method for producing a nanodispersion of nanocellulose in a first liquid medium, the method comprising:A) providing a nanodispersion of the nanocellulose in water, andB) while stirring, gradually adding said first liquid medium or one or more components thereof to the nanodispersion of the nanocellulose in water, thereby nanodispersing the nanocellulose in said first liquid medium, wherein the first liquid medium is a liquid other than pure water and is miscible with water.

[0016] Afterwards, the nanodispersion of nanocellulose in the first liquid medium can be used to produce ananodispersion of nanocellulose in a second liquid medium. Note that this second liquid medium does not need to be miscible with water, it only needs to be miscible with the first liquid medium. This will be further described in a section below describing optional step D).

[0017] It is important to note that, at step B), the first liquid medium is gradually added to the nanodispersion of the nanocellulose in water, not the reverse. In other words, in the method of the invention, the nanodispersion of the nanocellulose is NOT added to the first liquid medium.

[0018] It has indeed been unexpectedly found that the gradual addition of the first liquid medium to the nanodispersion of the nanocellulose in water prevents agglomeration of the nanocellulose in a wide range of liquid media, which is not possible when adding the nanodispersion of the nanocellulose in water to these liquid media. Thus, the method of the invention is, to the inventors’ knowledge, the easiest and most likely to succeed method for incorporating nanocellulose into a formulation without issues (agglomeration, destabilization of the formulation, etc.) and for achieving optimal nanodispersion.

[0019] The method of the invention also typically requires less mixing. For example, the need for sonication or other high-energy mixing techniques is typically reduced or eliminated.

[0020] The method of the invention also allows dispersing greater quantity of nanocellulose in a given liquid medium with a higher degree of dispersion.

[0021] It should be noted that the benefits conferred to a formulation by the presence of nanocellulose are highly dependent on the degree of dispersion and furthermore typically increase with nanocellulose concentration (up to a certain point before leveling off and / or decreasing). If dispersion quality is optimal, the maximum benefit might be achieved with a lower loading of nanocellulose. In addition, aggregated nanocellulose will often undesirably decrease performance or require increasing amounts of nanocellulose to obtain the same benefits. Examples of benefits imparted by nanocellulose include improving hardness and / or scratch resistance of coating materials, nucleation of crystallization in semi-crystalline polymers, which increases crystallization rate and temperature, polymer melt strength, which increases ease of processing polymer films, barrier properties, such as oxygen and grease barrier in coatings and composites, and improving cohesive strength of pressure sensitive adhesives. In these cases, these benefits cannot be obtained efficiently if aggregation occurs. The method of the invention allows to get these benefits more easily.

[0022] The fact that the method of the invention requires the presence of some water (introduced at step A)), is not a problem since this amount of water is minimized and can be removed without causing agglomeration of the nanocellulose. Thus, the method of the invention can be used to produce nanodispersions of nanocellulose in a first or second liquid medium in which no water is desired.

[0023] The first liquid medium in which the nanocellulose is nanodispersed is not particularly limited except that it is a liquid other than pure water and is miscible with water. The second liquid medium in which the nanocellulose is nanodispersed is not particularly limited except that it is a liquid other than pure water and that is miscible with the first liquid medium.

[0024] Herein, pure water means water in which no other substance has been purposefully added, solubilized, suspended, or dispersed. Tap water, distilled water, demineralized water, and deionized water all fall within the ambit of “pure water”.

[0025] Non-limiting examples of types of liquid media for the first and second liquid media include:• aqueous solutions, dispersions, and suspensions of a charge in water or in a non-aqueous liquid;• non-aqueous liquids including: o solvents, such as methanol, ethanol, dimethylformamide, dimethyl sulfoxide, acrylonitrile, acetone, tetrahydrofuran, 1 ,4-dioxane, ethyl lactate, and glycerol, o melted polymers, composites, and biocomposite polymers, and o carrying liquids, including melted solids;• liquid industrial formulations (aqueous and non-aqueous); as well as• liquid reactants (aqueous and non-aqueous), including liquid monomers e.g. for condensation polymerization.

[0026] A carrying liquid is a liquid that is miscible with two liquids, which themselves are immiscible with one another or that a user carrying out the method of the invention does not want to mix with one another. For example, the method of the invention starts with a nanodispersion of the nanocellulose in water and it is used to nanodisperse nanocellulose in PLA, which is not miscible with water. In such case, a carrying liquid that is soluble or miscible with both water and melted PLA should be used. The nanocellulose could first be dispersed in the carrying liquid, optionally water could be removed, and then the nanocellulose in the carrying liquid could then be dispersed in PLA. Non-limiting examples of carrying liquids include ethyl lactate, butanediol, glycerol, dimethylformamide, dimethylsulfoxide, ethylene glycol, and melted polyethylene glycol.

[0027] Non-limiting examples of melted polymers include polylactide (PLA), polybutylene adipate terephthalate (PBAT), polyethylene terephlalate (PET), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polylactate-co-hydracrylate (PLH), and polyhydroxyalkanoates (PHA’s).

[0028] Liquid industrial formulation are typically solutions, dispersions, or suspensions of a charge in a solvent e.g. water or a non-aqueous liquid. These include:• coatings of all kinds, including: o paints / primers / topcoats and the like; o protective coatings (protection against corrosion, UV, scratches, fingerprints, glare, smudge, or weather); o insulating coatings; o easy-to-clean coatings;o low-reflection or anti-reflection coatings; and o lubricants and friction reduction coatings,• sealants, and• adhesives (e.g., pressure sensitive adhesives, and epoxies).

[0029] The liquid reactants can comprise only one liquid reactant or a mixture of reactants, for example two or more liquid reactants mixed together or one or more solid reactant dissolved, dispersed, or suspended in a liquid reactant. Liquid reactants include reactants, such as monomers, for polymerization reactions, including condensation polymerization. Non-limiting examples of monomers include ethylene glycol, 1 ,4-butandiol (BDO), a mixture of adipic acid, 1 ,4-butanediol and terephthalic acid (which produces polybutylene adipate terephthalate (PBAT), a mixture of 1 ,4-butanediol and succinic acid (which produces polybutylene succinate (PBS)), and lactic acid

[0030] In embodiments, the nanodispersion of nanocellulose in the first or second liquid medium produced by the method of the invention has a cellulose nanocellulose of up to about 15 wt / wt%, preferably up to about 10 wt / wt%, and more preferably up to about 5 wt / wt%, based on the total weight of the nanodispersion. As the viscosity typically increases with the nanocellulose concentration, the viscosity may ultimately be the factor that determine the maximum nanocellulose concentration used, depending on the intended use for the nanodispersion produced by the method of the invention. Viscosity, and therefore maximum concentration, also depends on the surface charge of the nanocellulose, with higher concentrations being achievable for higher surface charge particles. Notably, the skilled person will know to use or refrain from using rheology modifiers and / or adjust the amount of solvent used in the end product to compensate for the effect of nanocellulose addition.

[0031] As well known to the skilled person, a “dispersion” as per the IUPAC definition is a mixture comprising more than one phase where at least one of the phases consists of finely divided phase domains, often in the colloidal size range, dispersed throughout a continuous phase. Herein, the term “nanodispersion” refers to a dispersion of nanosized solid particles in a continuous liquid phase, which is substantially free of agglomerates of these nanosized particles. Thus, the nanodispersion of nanocellulose in the first or second liquid medium produced by the method of the invention is a dispersion of nanocellulose in a continuous phase of the first or second liquid medium, which is substantially free of agglomerated nanocellulose.

[0032] Herein, the term “nanocellulose” refers to the types of cellulose knows as cellulose nanocrystals (CNCs), cellulose nanofibers (CNFs), and microfibrilated cellulose (MFC). These can be produced through chemical processes, mechanical processes, or a combination of the two. These may or may not have been surface modified, such as those containing ionic groups (sulfate, carboxylate, phosphate) or other types of modifications.

[0033] In embodiments, the nanocellulose is cellulose nanocrystals or cellulose nanofibers, preferably cellulose nanocrystals.

[0034] In embodiments, the cellulose nanocrystals are from about 2 to about 20 nm in diameter and from about 80 to about 400 nm in length, preferably from about 5 to about 10 nm in diameter and from about 100 to about 250 nmin length.

[0035] As noted above, cellulose nanofibers are mixtures of amorphous and crystalline cellulose. Microfibrilated cellulose (MFC) are essentially bundles of cellulose nanofibers. Generally speaking, CNFs will be characterized by a diameter of 100 nm or less, while the microfibrilated cellulose will tend to have larger diameters. However, both types of cellulose are typically sold as a mixture of CNFs and MFC.

[0036] In embodiments, the cellulose nanofibers are from about 5 to about 100 nm with an aspect ratio > about 30, preferably from about 5 to about 50 nm in diameter and an aspect ratio > about 50. In embodiments, the cellulose nanofibers have a length up to several micrometers.

[0037] In embodiments, the microfibrilated cellulose are from about 50 nm to about 10 000 nm in diameter, with an aspect ratio > 50. In embodiments, the microfibrilated cellulose have a length up to several micrometers.

[0038] In embodiments, the agglomerated nanocellulose is greater than 1000 nm in width and 1000 in length, preferably greater than 500 nm in width and 1000 nm in length, and more preferably greater than 400 nm in in width and 400 nm in length. In embodiments, the nanodispersion comprises less than 10 wt / wt% of the agglomerated nanocellulose, preferably less than 5 wt / wt%, preferably less than 1 wt / wt%, based on the total weight to the nanocellulose. Most preferably, the nanodispersion is free of agglomerated nanocellulose.

[0039] Indeed, agglomerates are undesirable because they can affect film quality (in the case of coatings), reduce the benefits that should be granted by the presence of nanocellulose, or have an impact on the properties of the polymer made from a liquid reactant. More specific examples include reducing film quality, smoothness, and gloss in coating applications, which often lead to a decrease in mechanical performance due to non-uniformity or defects in the coating. For plastic composite applications where nanocellulose acts as a nucleating agent and mechanical performance enhancer, aggregates significantly decrease the crystallization efficiency, have minimal impact on the polymer rheology for processing, and may not benefit mechanical performance unless high concentrations are used, when compared to nanodispersed nanocellulose. In pressure sensitive adhesive applications, aggregates can create defects in the adhesive film with high local concentrations of nanocellulose, which results in a decrease in adhesive properties.

[0040] Various methods can be used to ascertain the presence or absence of agglomerates in a dispersion. These techniques include optical microscope analysis, gloss level analysis, viscosity measurements, as well as visual assessment.

[0041] When well dispersed, nanocellulose should increase viscosity and have a shear thinning effect. Such effect is reduced or absent when agglomerates are present. Samples should ideally be allowed to rest for a minimum of 24 hours at room temperature before measuring viscosity.

[0042] A preferred way of confirming nanocellulose nanodispersion is using an optical microscope in transmission with crossed linear polarizers because nanocellulose agglomerates are birefringent and influence the polarization of the light. To perform this test, a drop of a sample is placed on a glass slide and covered with a coverslip and then thesample is observed under microscope. In the absence of agglomerates, the sample will appear dark and uniform. If agglomerates are present, they will show as larger bright particles that can be distinguished from the continuous phase of the sample.

[0043] Finally, if the nanocellulose is dispersed in a first or second liquid medium that is meant for medium-high gloss coating, a noticeable reduction of the gloss of the coating will be observed when nanocellulose agglomerates are present due to their light scattering effect. In other words, the coating will be more matte. No such gloss reduction is observed when the nanocellulose is well dispersed.

[0044] In some cases, visual assessment with the naked eye allows detecting agglomeration. Indeed, a liquid medium containing agglomerated nanocellulose may appear hazy and / or whitish and even exhibit some sedimentation, while a liquid medium will well nanodispersed nanocellulose may appear more uniform with no visible agglomerates or texture.Step A)

[0045] In embodiments, the nanodispersion of the nanocellulose in water provided at step A) is a commercially available CNCs nanodispersion in water, such as that available under the tradename “DextraCel® HS” sold by Anomera® Inc.

[0046] Alternatively, step A) can comprise nanodispersing dried nanocellulose, preferably dried CNCs, in water. In such embodiments, the nanocellulose is preferably nanodispersed in deionized or demineralized water. Depending on available mixing equipment for viscous systems, nanodispersion comprising up to 8 wt % or more of nanocellulose, based on the total weight of the nanodispersion, can be readily prepared.

[0047] Preferably, the dried CNCs are those available under the tradename “DextraCel® HP” sold by Anomera® Inc.

[0048] In embodiments, the nanodispersion of the nanocellulose in water provided at step A) has a nanocellulose concentration of up to about 5 wt / wt%, preferably up to about 8 wt / wt%, more preferably up to about 10 wt / wt%, and most preferably up to about 15 wt / wt%, based on the total weight of the nanodispersion.Step B)

[0049] As noted above, the first liquid medium or components thereof are gradually added to the nanodispersion of the nanocellulose in water. Herein, a gradual addition means that the first liquid medium or the components thereof is not added all at once, but rather little-by-little over an extended period of time, preferably using a method that minimizes the local concentration of the first liquid medium throughout the nanodispersion over the course of the addition.

[0050] In embodiments, the adding at step B) may last at least 5 minutes, preferably at least 10 minutes, and more preferably at least 15 minutes.

[0051] In embodiments, the first liquid medium or components thereof are added at step B) at an addition rate of at most 20% per minute, preferably at most 10% per minute, and most preferably at most 5% per minute. These percentages are either wt% or vol% based on the total weight or volume of the first liquid medium or components thereof. The addition rate does not need to be constant, it can vary in the above range with time, for example an addition rate gradient may be used.

[0052] In embodiments, the adding at step B) is carried out by spraying of droplets of, or by adding dropwise the first liquid medium or components thereof. Dropwise addition is particularly useful when preparing a lab-scale volume of nanodispersion, for example when adding a volume of first liquid medium or components thereof of about 50 mL or smaller.

[0053] Typically, during step B), viscosity of the mixture resulting from the addition of the first liquid medium or components thereof to the nanodispersion of the nanocellulose in water will first increase and then start decreasing. When the viscosity of the mixture starts decreasing any remainder of the first liquid medium or the components thereof can be added all at once. In preferred embodiments, in step B), the first liquid medium or components thereof is gradually added, thereby producing a mixture, until the viscosity of the mixture has risen and then started to decrease, then any remaining first liquid medium or components thereof is added to the viscous mixture. The remaining first liquid medium can be added all at once or at any desired rate. In preferred such embodiments, the first liquid medium or components thereof is added at such a rate that said decrease in viscosity is observed at least 5 minutes, preferably at least 10 minutes, and more preferably at least 15 minutes after said addition has started.

[0054] As noted above, the gradual addition in step B) is carried out while stirring. Any type of stirring can be used at step B) as long as the whole volume of the nanodispersion of the nanocellulose together with the first liquid medium moves. In embodiments, the stirring is carried out at 150-300 rpm, although this will be highly depend on the volume to be stirred. In embodiments, the stirring is carried out using a paddle- or anchor-type impeller.

[0055] It should be noted that at step B), “adding said first liquid medium or components thereof” means that when the liquid medium comprises more than one component, these components can be added consecutively rather than concurrently. If the liquid medium comprises more than one component, any subset of components can be added simultaneously or consecutively. All components of the liquid medium can be added in any order, but preferred embodiments in that regard are detailed below for each type of liquid medium.

[0056] In embodiments, the first liquid medium in which the nanocellulose are nanodispersed is:• Liquid Medium A: an aqueous solution, dispersion, or suspension of a charge in water, or• Liquid Medium B: a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a nonaqueous liquid,Liquid Medium A and Liquid Medium B being both miscible with water.

[0057] Herein, a “charge” is either a solid dissolved (thus a solute), dispersed, or suspended in either water or a non-aqueous liquid. The exact nature of the charge will depend on the intended use for the nanodispersion ofnanocellulose produced by the method of the invention.Liquid Medium A: Aqueous First Liquid Medium

[0058] In embodiments, the first liquid medium in which the nanocellulose are nanodispersed is Liquid Medium A i.e., an aqueous solution, dispersion, or suspension of a charge in water.

[0059] In such embodiments, the adding step, e.g., step B), preferably comprises: a) adding part of or all of (preferably all of) the water of the Liquid Medium A and stirring, thereby producing a mixture, and b) while stirring after step B’), gradually adding the charge of the Liquid Medium A to the mixture produced at B’), wherein the adding at step b) lasts at least 5 minutes.

[0060] During step a), the water can be added all at once. Alternatively, a slower addition is possible.

[0061] Typically, during step b), viscosity of the mixture to which the charge of the Liquid Medium A is added, will first increase and then start decreasing. When the viscosity starts decreasing any charge remaining can be added at once or at any other addition rate.

[0062] In embodiments, the adding step, e.g., step B), is carried out in a formulation vessel and comprises:1 ) adding part of or all of (preferably all of) the water of the Liquid Medium A to the formulation vessel and stirring, thereby producing a mixture of nanocellulose in water,2) while stirring, gradually adding the charge of Liquid Medium A to the formulation vessel until the viscosity of the mixture has risen and then started to decrease, thereby producing a viscous mixture, and3’) storing the viscous mixture for future use, and / or3”) adding any remaining charge of the Liquid Medium A to the formulation vessel, wherein the adding at step 2) lasts at least 5 minutes.

[0063] Non-limiting examples of types of Liquid Medium A (aqueous solutions, dispersion, or suspension of a charge in water) include any so-called waterborne industrial products (as long as they are miscible with water), such as:• waterborne coatings including: o paints / primers / topcoats and the like; o protective coatings (protection against corrosion, UV, scratches, fingerprints, glare, smudge, or weather); o insulating coatings;o easy-to-clean coatings; o low-reflection or anti-reflection coatings, and o waterborne lubricants and friction reduction coatings,• waterborne sealants, and• waterborne adhesives (e.g. waterborne epoxies).

[0064] Non-limiting examples of the Liquid Medium A include polyurethane dispersions (PUDs), polyacrylate (PAC) dispersions, polyurethane / polyacrylate (PU / PAC) hybrid dispersions, polyester / polyacrylate (PES / PAC) dispersions, polyisocyanate dispersions, alkyd dispersions, polyvinyl alcohol (PVA) dispersions, epoxy dispersions, and polyol dispersions, dispersions of copolymers thereof, and mixtures thereof; all of which including one-component (1 K) and two-component (2K) systems. As well known to the skilled person, the polymers in these dispersions can be modified in various ways. These can comprise crosslinker(s), catalyst(s), cosolvent(s), etc.

[0065] In preferred embodiments, the Liquid Medium A has a conductivity (ionic strength) 1000 uS / cm, preferably > 1200 uS / cm. The method of the invention works well for aqueous solutions or slurries with a conductivity < 1000 uS / cm but it is particularly useful for aqueous solutions or slurries with a conductivity about 1000 uS / cm as it can be very challenging or even impossible to nanodisperse nanocellulose using conventional methods in such liquid media. Indeed, minor to significant agglomeration of nanocellulose is typically observed when adding nanocellulose to such high ionic strength resins. Without being bound by theory, it is believed that the method of the invention helps preventing ionic strength shock of the nanocellulose. We note that surface charge and shape of the nanocellulose have an effect on the ionic strength resistance. At a given ionic strength, a nanocelllose with a lower surface charge, is less stable, and thus more difficult to nanodisperse. Therefore, the above ranges vary depending on the nanocellulose used.

[0066] In preferred embodiments, the Liquid Medium A is acidic. Typically, an acidic pH increases aggregation. However, especially when the conductivity (ionic strength) is 1000 uS / cm, preferably 1200 uS / cm, the method of the invention yields the desired nanodispersion even at acidic pH.

[0067] In preferred embodiments, the Liquid Medium A has a pH of < 7.

[0068] In preferred embodiments, the Liquid Medium A has a pH of > 2.

[0069] In preferred embodiments, the Liquid Medium A is free of cationic surfactant.

[0070] In embodiments, the Liquid Medium A may comprise one or more non-ionic and / or anionic surfactants.Liquid Medium B: Non-Aqueous First Liquid Medium

[0071] In alternative embodiments, the first liquid medium in which the nanocellulose are nanodispersed is the Liquid Medium B i.e., a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a non-aqueous liquid.

[0072] Typically, during the adding step, e.g., step B), the viscosity of the mixture to which the Liquid Medium B is added will first increase and then start decreasing. When the viscosity starts decreasing any remaining Liquid Medium B can be added at once.

[0073] In embodiments, the adding step, e.g., step B), is carried out in a formulation vessel and comprises:1) while stirring, gradually adding the Liquid Medium B to the formulation vessel, until a mixture is produced and the viscosity of the mixture has risen and then started to decrease, thereby producing a viscous mixture, and2a) storing the viscous mixture for future use, or2b) adding any remaining Liquid Medium B to the formulation vessel, wherein the adding at step 1) lasts at least 5 minutes.

[0074] Non-limiting examples of Liquid Medium B include:• carrying liquids such as polyethylene glycol and ethyl lactate;• non-aqueous water-miscible solvents such as methanol, ethanol, dimethylformamide, dimethyl sulfoxide, acrylonitrile, acetone, tetrahydrofuran, 1 ,4-dioxane, and glycerol;• monomers e.g., for condensation polymerization, such ethylene glycol, 1 ,4-butandiol (BDO), a mixture of adipic acid, 1 ,4-butanediol and terephthalic acid (which produces polybutylene adipate terephthalate (PBAT), a mixture of 1 ,4-butanediol and succinic acid (which produces polybutylene succinate (PBS)), and lactic acid; as well as• polymers, composites, and biocomposite polymers.Optional Step C) - Removing Water

[0075] It should be noted that, at the end of step B), the nanodispersion produced by the method of the invention will comprise water. Indeed, even if Liquid Medium B is used, some water will be present. This water originates at least from the starting nanodispersion of the nanocellulose in water provided in step A) of the method of the invention.

[0076] However, this water may be undesirable for further use of the nanodispersion. For example, some monomers are typically used in anhydrous form for polymerization.

[0077] Therefore, in embodiments, the method of the invention therefore further comprises the step C) of removing water from the nanodispersion produced at step B).

[0078] This can be achieved for example by heating above 100°C while mixing or by using a vacuum (e.g. a rotary evaporator) to lower the required temperature for removal, and heating at said temperature for removal. The optimal temperature, vacuum, and time will vary depending on the exact first liquid medium used. Preferably, in such cases,the amount of water used in the method of the invention is preferably limited so that less water needs to be removed afterwards.Optional Step D) - Nanodispersion in a Second Liquid Medium

[0079] In embodiments, the method of the invention further comprises the step D) of producing a nanodispersion of nanocellulose in a second liquid medium using the nanodispersion of nanocellulose in the first liquid medium, whether it is produced at step B) or C).

[0080] It is interesting to note that second liquid medium does not need to be miscible with water, rather it only needs to be miscible with the first liquid medium. Step D) thus allows producing nanodispersing nanocellulose in a broader selection of liquid media.

[0081] This is particularly useful when a nanodispersion in a liquid medium immiscible with water is desired. In such case, the first liquid medium can be a carrying liquid, which is miscible with both water and said liquid medium immiscible with water. Also, in such cases, optional step C) is preferably carried out before step D).

[0082] Non-limiting examples of such cases include the use of butanediol, ethyl lactate, and melted polyethylene glycol (PEG) as carrying liquids to achieve nanodispersion in melted polymers that are immiscible with water such as polylactide (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), and polyhydroxyalkanoates (PHA’s).

[0083] In preferred embodiments of step D), the first liquid medium is any one of claims 1 to a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a non-aqueous liquid, such as those described above.

[0084] In embodiments, step D) comprises mixing the nanodispersion of nanocellulose in the first liquid medium produced at step B) or C). This mixing can be achieved by any known method including for example, mixing by hand, mixing using a using standard overhead mixing, high shear mixing, extrusion, melt compounding, etc.

[0085] In embodiments, step D) comprises the same type of addition as that used in step B). Thus, step D) comprises, while stirring, gradually adding said second liquid medium or components thereof to the nanodispersion of the nanocellulose in the first liquid medium, thereby nanodispersing the nanocellulose in said second liquid medium, wherein the second liquid medium is miscible with the first liquid medium. Indeed, this is, in effect, the same as step B, expect for the following changes: the nanodispersion of the nanocellulose in water is replaced by the nanodispersion of nanocellulose in the first liquid medium as produced above, the first liquid medium is replaced by the second liquid medium, and a nanodispersion of the nanocellulose in the second liquid medium is produced.Therefore, all the above teachings regarding step B), including those in the sections on the aqueous and nonaqueous first liquid media apply to step D). Those are not repeated here for the sake of conciseness.Optional Step E) - Removing the First Liquid Medium

[0086] In embodiments, the method of the invention further comprises step E) of removing the first liquid medium from the nanodispersion produced at step D). This step is optional as, in some cases, the first liquid medium can be left in the nanodispersion without trouble.

[0087] Typically, when the first liquid medium is a melted solid (such as PEG), it can be more practical to leave it in the nanodispersion. When the first liquid medium is a liquid, it can more easily be removed, for example by evaporation.Optional Step F) - Repeating Step D)

[0088] In embodiments, the method of the invention further comprises the step F) of repeating step D) or steps D) and E) one or more times, each time producing a nanodispersion of nanocellulose in a further liquid medium using a nanodispersion of nanocellulose produced during the immediately preceding step ii). In such embodiments, each further liquid medium is miscible with the liquid medium of the nanodispersion of nanocellulose produced during the immediately preceding step D).

[0089] This is useful when one cannot find a carrying liquid that is miscible with both water and the liquid medium of the desired nanodispersion. Then, two or more carrying liquids can be used consecutively: the first carrying liquid being miscible with water and the second carrying liquid and the second carrying liquid being miscible with the first carrying liquid and a third carrying liquid, and so on until one carrying liquid is miscible with the liquid medium of the desired nanodispersion.Step D) as a Standalone Method

[0090] The above step D), when it comprises the same type of addition as that used in step B), can also be used on its own. This is useful for example, when one party produces a nanodispersion of nanocellulose in a first liquid medium (for example using the above method) and then provide this nanodispersion, commercially or otherwise, to another party, which then uses this nanodispersion to produce a nanodispersion of nanocellulose in the second liquid medium.

[0091] In such embodiments, the nanodispersion of the nanocellulose in water is replaced by a nanodispersion of nanocellulose in a liquid medium other than water and the rest of the method is the same as above with the exception that the first liquid medium does not need by the miscible with water, but rather needs to be miscible with the second liquid medium. These teachings are not repeated here for the sake of conciseness.

[0092] The nanodispersion of nanocellulose in a liquid medium other than water may be any such nanodispersion. Non-limiting examples include: commercially available nanodispersions of nanocellulose, nanodispersions of nanocellulose prepared using methods other than the method of the invention (steps A)and B)), and nanodispersions prepared of nanocellulose using the method of the invention as defined above, either by a same or by a different party.Definitions

[0093] The use of the terms "a" and "an" and "the" and similar referents in the context of describing the invention (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context.

[0094] The terms "comprising", "having", "including", and "containing" are to be construed as open-ended terms (i.e., meaning "including, but not limited to") unless otherwise noted. In contrast, the phrase “consisting of’ excludes any unspecified element, step, ingredient, or the like. The phrase “consisting essentially of” limits the scope to the specified materials or steps and those that do not materially affect the basic and novel characteristic(s) of the invention.

[0095] Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. All subsets of values within the ranges are also incorporated into the specification as if they were individually recited herein.

[0096] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context.

[0097] The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention unless otherwise claimed.

[0098] No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the invention.

[0099] Herein, the term "about" has its ordinary meaning. In embodiments, it may mean plus or minus 10% or plus or minus 5% of the numerical value qualified.

[0100] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0101] Other objects, advantages and features of the present invention will become more apparent upon reading of the following non-restrictive description of specific embodiments thereof, given by way of example only with reference to the accompanying drawings.DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0102] The present invention is illustrated in further details by the following non-limiting examples.

[0103] The Examples below make use of the CNCs commercially available from Anomera®, Montreal, Canada, under the tradename DextraCel®, FIG. 2 is a TEM micrograph is these CNCs. They are available aggregated in a micro-powder form that can be redispersed in water shown in FIG. 3 (DextraCel HP) as well as an aqueous suspension containing 8-10 wt% CNCs (DextraCel HS).

[0104] Example 1 shows how to produce a suspension like DextraCel HS from the powder DextraCel HP. DextraCel HS was used in the remaining examples.Example 1 - Nanodispersion of DextraCel HP in Water

[0105] When starting with DextraCel HP, an aqueous dispersion of the CNCs must be prepared so it can be used in the method of the invention. To this end, CNCs powder was mixed with deionized (DI) water to disperse the CNC crystals back to the nanoscale. More specifically, DextraCel HP powder has been added to deionized / demineralized water at a level of 5-8wt% solids and mixed well at 1000+ rpm for 1 hour. In some cases, general mixing equipment, such as an overhead mixer, was successfully used for dispersion. In other instances, higher shear equipment was used and observed to promote faster dispersion.

[0106] Good dispersion was obtained at both 1 and 5 wt% after mixing for 1 and 2 hours respectively and dispersion was not dependent on concentration below 5 wt%.

[0107] CNCs continue to disperse after initial mixing is stopped. Therefore, it was observed that it is optimal to wait minimum 24 hours following dispersion before using of CNC suspension.

[0108] Once properly dispersed in water, it was observed that the CNCs remained stable in water for extended periods of time (tested up to 3 years with no issues so far).Example 2 - Nanodispersion of CNCs in Waterborne Coatings using a Conventional Method - COMPARATIVE EXAMPLE

[0109] DextraCel HS has been tested and found to have good compatibility with low ionic strength (conductivity < 850 uS / cm) waterborne resins systems, such as waterborne polyurethane dispersions (PUDs), waterborne polyurethane acrylate dispersions PUAs, and water-based acrylics. Specific examples of tested resins include Bayhydrol XP 2637 (polyurethane dispersion - conductivity = 850 uS / cm) and Bayhydrol UH 2952 / 1 (polyurethane dispersion - conductivity = 610 uS / cm).

[0110] In such cases, DextraCel HS was simply added to the formulation with the water that was to be added to the resin system after adding the resin component. More specifically, the resin was first added to the formulation vessel. Separately, DextraCel HS was diluted with any additional water that was destined to be added to the formulation (if any). Then, the water / DextraCel mixture was added to the resin with standard mixing.

[0111] Specifically, for Bayhydrol UH 2952 / 1 , the procedure was as follows. Bayhydrol UH 2952 / 1 (40 g) was added to a 140 mL beaker equipped with an overhead mixer and mixed at 300 rpm. DextraCel (4.0 g, 8.1% in water,never dried) was then added dropwise to the resin while mixing. Total addition time was ~10 minutes. The viscosity of the mixture gradually increased during the process. Following the complete addition of CNC’s, mixing was continued for 5 minutes before collecting the final sample.

[0112] In contrast to low ionic strength mixture, minor to significant CNC agglomeration was observed when adding DextraCel HS to high ionic strength resins, such as WLS-213, using the above conventional method. This affected the final film quality (result shown in Example 3) and limited the obtained benefits. Indeed, a high level of CNC dispersion is required to achieve optimal benefits, such as increase in hardness and scratch resistance.Example 3 - Nanodispersion of CNC in Waterborne Coatings Using the Method of the Invention

[0113] The method of the invention was found to increase likelihood of incorporating CNC into a formulation with no issues (agglomeration, destabilization of the resin, etc.) and achieve optimal dispersion. Indeed, the method of the invention was used to disperse CNCs in resin with low ionic strength and achieved complete dispersion. More interestingly, the method of the invention was used with the following high ionic strength resins to successfully disperse CNC: WLS-213 sold by DIC®. Other resins with higher ionic strength that were tested using this method include listed in the table below.

[0114] When using the method of the invention, instead of adding the resin to formulation vessel, followed by CNC / water, the reverse was done. CNC was added to the formulation vessel first, followed by any additional water in the formulation, and then the resin was slowly added with good mixing. Initially, the viscosity of the suspension rose as more resin was added. This was followed by a decrease in viscosity after a certain amount of resin was added. Once all the resin was added, the resin could be used and formulated as normal. The basic procedure was as follows:1 . DextraCel was added to the formulation vessel with standard mixing, along with any water that would normally be added with the resin. Mixing speed was adjusted if necessary to ensure good mixing of the entire volume.2. The resin was then gradually added (dropwise was preferred at the beginning, especially for smaller volumes, such as < 50 mL). The viscosity of the stock solution increased abruptly, and a gel-like mixture would form in most cases.3. Slow addition of the resin was continued until the viscosity began to drop (as evaluated visually). When desired, after step 3, the gel-like material could be stored for later use without compromising dispersion.4. The remaining resin was then added to the gel-like material and mixed as indicated for the specific resin used. The total addition time was about 10 - 15 minutes.

[0115] Specifically, for WLS-213, the procedure was as follows. DextraCel HS (6.48 g, 8.1 wt% in water) was added to a 140 mL beaker equipped with an anchor blade type impeller and mixed at 300 rpm to ensure good mixingof the entire volume. WLS-213 resin (50 g, 40 wt% in water) was then slowly added dropwise to the DextraCel suspension. Total addition time was ~10 minutes. After addition of the WLS-213 was complete, the mixture was allowed to stir for an additional 2 minutes before collecting the final sample.* Film quality too poor for gloss measurement** Adhesive resin - gloss not measuredExample 4 - Assessing CNC Dispersion

[0116] This section provides techniques that can be used to assess the dispersion quality when CNCs are mixed with a resin. The characterization techniques used are optical microscope analysis, gloss, and viscosity. One or more of these techniques were applied to the liquid systems tested in Example 3. In each case, good dispersion was obtained using the method of the invention (as per Example 3) and poor dispersion was obtained using the conventional method (as per Example 2). The results below show examples of what can be observed in the case of agglomeration. More specifically, we report here results for WLS-213.

[0117] Viscosity. Viscosity was used as an indicator of CNC compatibility with a liquid system. If well dispersed, CNCs should add a viscosity boost and a shear thinning effect when mixed with a resin. If aggregation occurs, minimal change, or in some cases, a decrease in viscosity is observed.

[0118] See Figure 4 for an example of the effect of dispersion on viscosity of WLS-213. The method of the invention (Example 3) yielded a moderate viscosity boost, indicating good dispersion. The conventional method (Example 2) showed no change in viscosity compared to the control sample (same resin system without CNC). Samples were allowed to sit for a minimum of 24 hours at room temperature before measuring viscosity using a Brookfields viscometer.

[0119] Agglomeration / Flocculation (Optical Microscope Analysis). In some cases, visual assessment allowed seeing agglomeration during formulation, but in many cases the agglomerates were too small to observe with the naked eye. Therefore, an optical microscope was used to confirm CNC dispersion by looking for small agglomerates. The quality of the dispersion was thus assessed by looking at the samples under a polarized optical microscope with crossed linear polarizers. Under polarized light, CNC aggregation was detected in the samples by observing the birefringence of the suspensions with crossed linear polarizers. Large agglomerates showed as bright areas within the sample, while areas with little or no CNC agglomerates appeared black.

[0120] To do this, a drop of the resin / CNC mixture of either Example 2 or 3 was placed on a glass slide and covered with a coverslip. The sample was then analyzed under crossed linear polarizers. When no agglomeration was present, the sample appeared dark and uniform. When agglomerates were present, they appeared as large bright particles because CNCs influences the polarization of the light.

[0121] FIG. 5A and B show the images of 3 wt% DextraCel in WLS-213 resin from DIC® dispersed using either method. A good dispersion was achieved using the method of the invention (Example 3) with no agglomeration observed. However, using the conventional method (Example 2), we could clearly see visible agglomeration. For this resin, compatibility with the formulation could only be achieved using the method of the invention (Example 3).

[0122] Gloss. Another indicator of CNC agglomeration, useful mainly in medium-high gloss applications, is a noticeable reduction of gloss in the final coated film due to light scattering by agglomerates.

[0123] FIG. 6 shows a visual example of this effect with 3 wt% loading of DextraCel in WLS-213 relative to the solids. As with the microscopy analysis, the different methods given above have a significant effect on the final gloss, with the method of the invention preserving the gloss (FIG.6A) and the conventional method giving a matte effect (FIG 6B). Gloss was measured as follows:• Gloss (at 60°) resin without CNC = 84 %• Gloss (at 60°) good dispersion, method of Example 3 = 84 %Gloss (at 60°) poor dispersion, method of Example 2 = 50 %.Example 5 - Using CNCs for Condensation Polymerization

[0124] Agglomeration of the CNCs was observed when adding DextraCel HS to a 1 ,4-Butanediol (BDO) monomer. This was especially true when the CNC suspension was added to a stirring solution of BDO. It is believed that the water from the DextraCel HS droplets rapidly diffused into the BDO, which caused CNC to quickly agglomerate.Example 5.1 - Nanodispersion of DextraCel in 1 ,4-butandiol (BDO) using the method of the invention and the conventional method

[0125] To ensure a high level of dispersion of CNC in BDO with minimal water added and without the need for sonication or other high energy techniques, we added the BDO slowly to a suspension of DextraCel as per the method of the invention. More specifically, DextraCel HS (12.3 g, 8.1 % in water) was added to a 140 mL beaker equipped with an anchor blade type impeller and mixed at 300 rpm to ensure good mixing of the entire volume. BDO (87.7 g) was then slowly added dropwise to the DextraCel suspension. Total addition time was ~10 minutes. Mixing speed was gradually increased to 400 rpm as the volume and viscosity increased to ensure good mixing. After addition of the BDO was complete, the mixture was allowed to stir for an additional 2 minutes before collecting the final sample. Final concentrations: DextraCel: 1.0 wt%; Water: 11.3 wt%; BDO: 87.7 wt%.

[0126] For comparison, we also tried dispersing DextraCel in BDO using the conventional method. More specifically, BDO (125 g) was added to a 140 mL beaker equipped with an overhead mixer and mixed at 300 rpm. DextraCel (7.5 g, 8.1% in water, never dried) was then added dropwise to the BDO. Total addition time was ~10 minutes. The viscosity of the mixture did not change during the process. Following the complete addition of CNC’s, mixing was continued for 5 minutes before collecting the final sample. Final concentrations: DextraCel: 0.5 wt%; Water: 5.2 wt%; BDO: 94.3 wt%.

[0127] Visual characterization of DextraCel in BDO. FIG. 7 shows the difference between good dispersion of DextraCel in BDO that was achieved using the method of the invention, and poor dispersion which was achieved when DextraCel was added directly to BDO. When DextraCel was added directly to BDO, sedimentation occurred rapidly, while the method of the invention generated a uniform translucent suspension.Example 5.2 - Nanodispersion of DextraCel in 1 ,4-butandiol (BDO) and succinic acid (SA) using the method of the invention and the conventional method

[0128] When DextraCel HS was added into a solution of BDO and SA through direct addition, large agglomerates formed. It is believed that rapid protonation of the carboxylated groups on the cellulose nanocrystals led to coagulation of the DextraCel HS droplets. However, it was possible to avoid these large agglomerates and prepare well dispersed DextraCel suspensions in this system using the method of the invention.

[0129] Preparation of DextraCel BDO / SA mixture. DextraCel HS at concentration of 8.5 wt% in water was usedto to minimize the addition of water. A fully dissolved (transparent) solution of 4 g of SA in 55 g BDO was prepared by heating the mixture to 60 °C. A 100 mL beaker was then loaded with 7.06 g of DextraCel HS (8.5% in water) and mixed at 500 rpm using an overhead mixer and a crossed blade impeller. Once mixed, the prepared SA / BDO solution was slowly added dropwise to the DextraCel over the course of 15 minutes. Viscosity quickly rose during the initial addition, and mixing was adjusted as necessary during the addition (up to 1000 rpm at the most viscous) to ensure mixing of the entire volume. At the end of addition, the mixing speed was adjusted to 650 rpm and left to mix for an additional 5 minutes before collecting the sample. Final concentrations: DextraCel: 0.9 wt%, Water: 9.8 wt%, BDO: 83.2wt%, SA: 6.1.

[0130] For comparison, we also tried dispersing DextraCel in BDO / SA using the conventional method. More specifically, a solution of 4 g of SA in 50 g BDO was prepared by heating the mixture to 60 °C in a 100 mL beaker. The SA / BDO solution was then mixed at 650 rpm using an overhead mixer and a crossed blade impeller. DextraCel HS (7.06 g, 8.5 wt% - 0.6 g) was then slowly added dropwise the SA / BDO solution over ~10 minutes. The final suspension was mixed for an additional 5 minutes before collecting the sample. Final concentrations: CNC: 0.9 wt%; Water: 9.8 wt%; BDO: 83.2 wt%; SA: 6.1 wt%.

[0131] Visual characterization of DextraCel in BDO / SA. FIG 8 shows the difference between good dispersion of CNCs in BDO / SA that was achieved using the method of the invention, and poor dispersion achieved when CNCs were added directly to BDO / SA. When DextraCel HS was directly added to BDO / SA, the suspension appeared more hazy and opaque with some sedimentation (right-hand tube), due to the formation of small agglomerates, while Anomera’s new addition method appears more uniform with no visible agglomerates or texture (left-hand tube).

[0132] Agglomeration / Flocculation (Optical Microscope Analysis). A drop of the suspension was placed on a glass slide and covered with a cover slip. Then, the sample was observed. FIG. 9A to D and Figure 10A to D show the results for well dispersed CNC obtained by the method of the invention and poorly dispersed CNC prepared by the conventional method. Note the large agglomerates present in the sample prepared by adding CNCs directly to BDO / SA, which we believe were due to rapid coagulation of the DextraCel suspension droplets as they were added to the butanediol. In contrast, dispersions prepared using the method of the invention had a uniform texture and showed birefringence throughout the entire sample.

[0133] In both cases (BDO alone and with SA), using the method of the invention led to a much more uniform distribution of CNCs in the final suspension.

[0134] Viscosity. Viscosity was measured using a Brookfield® viscometer at various speeds using spindle #10. As can be seen in Table 1 , when a good dispersion was obtained i.e., when the method of the invention was used, the viscosity of the suspension increased significantly and gave a shear thinning behavior. In contrast, when CNCs were added directly to BDO / SA, there was significant agglomeration and no increase in viscosity was observed.

[0135] Table 1 . Brookfields viscosity comparing the method of the invention for DextraCel addition to the conventional method of adding the DextraCel directly to the BDO.

[0136] Table 2. Brookfields viscosity comparing the method of the invention for DextraCel addition to the conventional method of adding the DextraCel directly to the BDO / SA mixture.

[0137] As can be seen from the viscosity data in FIG. 11 , the method of the invention led a much larger increase in viscosity and shear thinning behavior when compared to the conventional method. Like the optical microscope images, this indicates that dispersion quality is significantly improved when the method of the invention is used.Example 5.3 - Removal of water from the above nanodispersions of CNCs in BDO and BDO / SA

[0138] Water was removed from the mixtures obtained in Example 5 to yield stable suspensions of CNC in only the monomer(s). This was done by simple heating of the mixtures while mixing. Some monomer evaporation was expected, depending on the temperature / monomer used.

[0139] CNC remained well dispersed in both BDO only and BDO / SA after removal of water from the system. Indeed, after removal of water, the samples obtained using the method of the invention were examined through a circular polarizer upon illumination with linearly polarized light. As can be seen in FIG. 12, both samples showed strong birefringence, indicating that the quality of the dispersion was not affected by water evaporation or heat.

[0140] FTIR was used (FIG. 13) to prove the water had indeed been removed. The peak at 1650 cm1attributed to water was absent in the spectra of the heated the samples. Additionally, some esterification was observed in the sample containing SA (-1732 cm1) as a result of the temperature used for water removal.Example 6 - Nanodispersion of CNC in poly(butyl-adipate-terephthalate) (PBAT) using the method of the invention and the conventional method

[0141] Using the method of the invention, it was also possible to achieve high levels of dispersion of CNC in various polymer matrices. Specifically, for PBAT, the procedure was as follows: CNC dispersed in BDO (2 wt%, 30 g) with water removed prepared by the method in Example 5 followed by Example 6 was added to a beaker and heated to 175 °C while stirring at 60 RPM with an overhead mixer. Once heated, pellets of PBAT (30 g) were slowly added and melted into the CNC / BDO mixture over 20 minutes. Mixing continued for an additional 20 minutes to fully incorporate the CNC into the mixture and allow BDO to evaporate to obtain the nanocomposite polymer where the CNC content was 2% relative to the PBAT.

[0142] A comparative example where CNC in BDO was added to the polymer melt in water was done as follows: 30 g PBAT was melted at 175 °C in a 140 mL beaker equipped with an overhead mixer. Once the polymer was melted, the mixer was turned on at 40 rpm. To the melted PBAT, CNC dispersed in BDO (2wt%, 30 g) with water removed prepared by the method in Example 5 followed by Example 6 was added over 1 minutes. Once all the CNC / BDO was added, mixing was continued for an additional 20 minutes to allow BDO to evaporate and obtain the nanocomposite polymer where the CNC content was 2% relative to the PBAT.

[0143] Agglomeration (Optical Microscope Analysis). The polymer containing CNC was melted and a drop placed on a microscope slide, followed by a coverslip. This was then further heated on a hotplate to ensure the polymer was fully melted before analysis using an optical microscope to image the sample. FIGS. 14A and 4B show the results for well dispersed CNC obtained by the method of the invention (FIG. 14A) and poorly dispersed CNC prepared by the conventional method (FIG. 14B). Note the presence of many small and large agglomerates present in the sample prepared by the comparative method. In contrast, composites prepared using the method of the invention had a uniform texture and showed little to no sign of large agglomerates of CNC.Example 7 - Nanodispersion of CNC in Polyethylene Glycol

[0144] DextraCel HS (8.1 wt%, 617.3 g) was added to a 2 L beaker, equipped with an overhead mixer and heated to 75 °C. In a separate 2L beaker, 1000 g of polyethylene glycol (PEG, Mw = 3340 g / mol) was fully melted by heating to 75 °C. The melted PEG was slowly to the DextraCel HS slurry with mixing. The first 300 g of PEG were added in 10 mL increments to allow slow incorporation into the DextraCel HS, increasing mixing as required to ensure the entire volume was moving. After 300 g, the rate of PEG addition was gradually increased until all PEG had been added, with the total addition time taking approximately 15 minutes. Viscosity increased significantly in the latter parts of the addition process.

[0145] After complete addition PEG, water was removed by transferring the material to aluminum sheets and placing in a convection oven at 90 °C for 16 hours, followed by thoroughly mixing the material by hand before placing in a vacuum oven at 90 °C for an additional 4 hours. Following drying, the material was cooled to room temperature to solidify, and ground to a powder form for future use. The final product consisted of 5% CNC, 95% PEG, and contained <0.2% moisture measured by a moisture analyzer.

[0146] Agglomeration (Optical Microscope Analysis). The product was further analysed for agglomeration / flocculation using optical microscopy. Solid CNC / PEG was placed on a glass slide, heated to 90 °C to melt the material, and covered with a coverslip. This was then imaged at 500 x between cross polarizers to looked for birefringence. Throughout the sample, the birefringence was uniform (FIG. 15) indicating good dispersion of CNC was achieved. No signs of agglomeration were observed.Example 8 - Nanodispersion of CNC in Ethyl Lactate

[0147] DextraCel HS (8.1 wt%, 309 g) was added to a 1 L beaker, equipped with an overhead mixer and mixed at 200 rpm. Ethyl lactate (500 g, liquid) was slowly added the DextraCel HS slurry. The first 150 g of ethyl lactate were added in 5 mL increments to allow slow incorporation into the DextraCel HS, increasing mixing as required to ensure the entire volume was moving. After 150 g, the rate of ethyl lactate addition was gradually increased until all ethyl lactate had been added, with the total addition time taking approximately 15 minutes.

[0148] After complete addition of ethyl lactate, water was removed by evaporation at elevated temperatures while mixing to yield a stable CNC / ethyl lactate suspension. The final suspension consisted of 5% CNC, 95% ethyl lactate, and < 0.5 % water content.Example 9 - Nanodispersion of CNC / Ethyl Lactate in PBS using the Method of the Invention

[0149] CNC dispersed in ethyl lactate (5 wt%, 30 g) prepared by the method in Example 9 was added to a beaker and heated to 140 °C. Once heated, pellets of PBS (30 g) were slowly added and melted into the CNC / ethyl lactate mixture over 20 minutes and gradually incorporated in the CNC / ethyl lactate suspension with mixing by hand. Once all the PBS was added, the temperature was increased to 175 °C and mixing continued for an additional 20 minutes to fully incorporate the CNC into the mixture and allow ethyl lactate to evaporate to obtain the nanocomposite polymer where the CNC content was 5% relative to the PBS. The 5% masterbatch was then further diluted by adding additional polymer to achieve final concentrations of 1 and 0.2%. Samples were further dried under vacuum at 80 °C to remove residual ethyl lactate.

[0150] Agglomeration (Optical Microscope Analysis). A small piece of the polymer containing CNC was placed on a microscope slide and melted at 200 °C, followed by a coverslip. The melted polymer was analyzed using an optical microscope to image the sample. FIG. 16 shows a representative image of the sample containing 2% CNC at 500x under crossed polarizers. For comparison, neat PBS is also shown. Throughout the sample, the birefringencewas uniform indicating good dispersion of CNC was achieved. No significant agglomeration was observed.Thermal analysis (DSC). The crystallization temperature and rate of the CNC / PBS composites was analysed by DSC by first heating to 160 °C to fully melt the polymer, and cooling at various rates from 10 to 50 °C / min. Crystallization temperatures can be found in the table below, where addition of CNC increases the crystallization temperature at all rates. FIG. 17 shows the normalized total enthalpy vs temperature during cooling at 30 °C / min, where the rate of crystallization is significantly increased when CNC is present.Table. Crystallization temperatures for PBS nanocomposites containing CNC at various cooling ratesExample 10 - Nanodispersion of CNC / PEG in PLA by Compounding

[0151] CNC / PEG (5 wt% CNC, 6 g) was dispersed in PLA (Natureworks®, grade 3100 HP, 9 g) by melt compounding the two materials together using a micro compounder at 100 rpm and 180 °C for 5 minutes. Prior to compounding, the PLA was dried 80 °C under vacuum for 4 hours to remove moisture. The extruded filament was cooled and pelletized to yield a polymer with 60% PLA, 38% PEG, and 2 % CNC.

[0152] The above PLA containing 2% CNC (1 .5 g) was further used as a masterbatch and compounded with additional PLA (13.5 g) under the same conditions. The extruded filament was cooled and pelletized to yield a polymer with 95.8% PLA, 3.8% PEG, and 0.2 % CNC.

[0153] Agglomeration (Optical Microscope Analysis). A small piece of the polymer containing CNC was placed on a microscope slide and melted at 200 °C, followed by a coverslip. The melted polymer was analyzed using an optical microscope to image the sample. FIG. 18 shows a representative image of the sample containing 2% CNC at 500x under crossed polarizers. Throughout the sample, the birefringence was uniform indicating good dispersion of CNC was achieved. No signs of agglomeration were observed.

[0154] Thermal analysis (DSC). Isothermal crystallization rate of PLA containing CNC was determined using DSC. The PLA composites were first heated to 200 °C and held for 3 minutes to fully melt the PLA, followed by rapid cooling to 105 °C. The heat flow curve can be seen in FIG. 19, where the curves correspond to a ti / 2 crystallization time of approximately 12 minutes for neat PLA, and 0.67 minutes for samples containing 0.2% CNC / 4% PEG.Example 11 - Nanodispersion of CNC / Ethyl Lactate in PBAT by Compounding

[0155] CNC / Ethyl lactate (5 wt% CNC, 6 g) was dispersed in PBAT (14.7 g) by melt compounding the two materials together using a micro compounder at 100 rpm and 165 °C for 5 minutes. The extruded filament was cooled, pelletized, and dried in a vacuum over at 90 °C for 6 hours to yield a polymer with 98% PBAT and 2 % CNC.

[0156] The above PBAT containing 2% CNC (1 .5 g) was further used as a masterbatch and compounded with additional PLA (13.5 g) under the same conditions. The extruded filament was cooled and pelletized to yield a polymer with 99.8% PBAT and 0.2 % CNC.

[0157] Agglomeration (Optical Microscope Analysis). A small piece of the polymer containing CNC was placed on a microscope slide and melted at 180 °C, followed by a coverslip. The melted polymer was analyzed using an optical microscope to image the sample. FIG. 20 shows a representative image of the sample containing 2% CNC at 500x under crossed polarizers. Throughout the sample, the birefringence was uniform, indicating good dispersion of CNC was achieved. No signs of agglomeration were observed.Thermal analysis (DSC). The crystallization temperature of the CNC / PBAT composites was analysed by DSC by first heating to 160 °C to fully melt the polymer, and cooling at various rates from 10 to 50 °C / min. Crystallization temperatures for neat PBAT and PBAT + 0.2% CNC can be found in the table below, where addition of CNC increases the crystallization temperature at all rates. FIG. 21 shows the normalized heat flow during 10 °C / min, where a 44 °C shift in the crystallization peak can seen for neat PBAT and PBAT containing 0.2 % CNC. Table. Peak crystallization temperatures for PBAT nanocomposites containing CNC at various cooling rates.Example 12 - Scale-up of Nanodispersion of CNC / Ethyl Lactate in PHBH by Extrusion

[0158] 60 kg of DextraCel aqueous suspension (8.1 wt%) was added to a mixing tank equipped with an overhead mixer. Ethyl lactate (90 kg) was then added to the tank at a constant rate through a spray ball, to minimize the size of the solvent droplets, over the course of 60 minutes. Mixing speed was adjusted to ensure good mixing of the entire volume during addition. After the addition was complete, mixing was continued for an additional 30 minutes.

[0159] 11 kg of the above slurry were then transferred to an evaporation flask and water was then removed from the slurry using a rotary evaporator with the batch temperature set to 70 °C and vacuum at -700 mmHg until the water content was below 1 wt%. The ethyl lactate dispersion was then diluted to with additional ethyl lactate toimprove flowability, filtered through a 400 um mesh sieve, and collected to yield a final slurry of 5.6 wt% CNC in ethyl lactate.

[0160] The CNC / Ethyl lactate was then incorporated into PHBH polymer by using a twin-screw extruder equipped with a vacuum port. Neat PHBH was stabilized in the extruder with temperatures set to 140 - 160 °C, screw speed at 130 rpm, and polymer feed rate to 1 kg / hour. Once a stable filament was achieved, CNC / Ethyl lactate was injected into stage 2 of the extruder at a rate of 15 g / minute, yielding a final polymer composite with 5 wt% CNC relative to the PHBH. Ethyl lactate content in the collected polymer was 5 wt%. The filament was pelletized and dried in an over at 60 °C for 24 hours to achieve a final moisture content < 0.1 wt%.Agglomeration (Optical Microscope Analysis).

[0161] A small amount of the PHBH polymer containing CNC was placed on a microscope slide, followed by a coverslip. The sample was then heated on a hotplate set at 140 °C to fully melt the polymer before analysis using an optical microscope to image the sample between crossed linear polarizers. Figure 22 show the results for well dispersed CNC obtained by the method of the invention, where the sample is brightly lit and uniform throughout as a result of the birefringence of the dispersed CNCs, with no dense agglomerates present, which would appear as localized bright spots in the sample. In contrast, a sample of the neat PHBH analyzed under the same conditions (not shown) showed a completely black image with no birefringence.Example 13 - Dispersion of CNFs in Ethyl lactate using the method of the invention and the conventional method

[0162] Method of the invention. 25 g of a 1 wt% suspension of cellulose nanofibers in water, prepared by (2,2,6,6-tetramethylpiperidin-1 -yl)oxyl (TEMPO) oxidation and containing surface carboxylate groups, were added to 150 mL beaker equip with a high shear mixing blade and mixed at 300 rpm. To the mixture, 25 g of ethyl lactate was added dropwise over the course of 15 minutes. Following complete addition of the solvent, the mixture was allowed to mix for an additional 5 minutes before being collected.

[0163] Conventional method. 25 g of ethyl lactate was added to a 150 mL beaker equipped with a high shear mixing blade and mixed at 300 rpm. To the solvent, 25 g of CNF’s were slowly added dropwise over the course of 15 minutes. Following complete addition of the suspension, mixture was allowed to mix for an additional 5 minutes before being collected.

[0164] As the starting CNF sample contains some agglomerates or large fibrous particles, comparison of the dispersions by microscope was difficult. Instead, viscosity was used, where high viscosity while maintaining the strong shear thinning effect indicates improved dispersion of the cellulose nanofibers in the solvent mixture (see the table below).

[0165] Table. Brookfields viscosity comparing the method of the invention to the conventional method of mixing CNF with ethyl lactate

[0166] The scope of the claims should not be limited by the preferred embodiments set forth in the examples but should be given the broadest interpretation consistent with the description as a whole.REFERENCES• The present description refers to a number of documents, the content of which is herein incorporated by reference in their entirety. These documents include, but are not limited to, the following: WO 2016 / 015148 • WO 2020 / 227816• WO 2020 / 163948• WO 2020 / 227814• WO 2020 / 227815• WO2018100061

Claims

CLAIMS:

1. A method for producing a nanodispersion of nanocellulose in a first liquid medium, the method comprising:A) providing a nanodispersion of the nanocellulose in water, andB) while stirring, gradually adding said first liquid medium or one or more components thereof to the nanodispersion of the nanocellulose in water, thereby nanodispersing the nanocellulose in said first liquid medium, wherein the first liquid medium a liquid other than pure water and is miscible with water.

2. The method of claim 1, wherein the nanodispersion of the nanocellulose in water provided at step A) is a commercially available CNCs nanodispersion in water, such as that available under the tradename “DextraCel® HS” sold by Anomera® Inc.

3. The method of claim 1, wherein step A) comprises nanodispersing dried nanocellulose, preferably dried cellulose nanocrystals, more preferably dried CNCs available under the tradename “DextraCel® HP” sold by Anomera® Inc., in water.

4. The method of any one of claims 1 to 3, wherein the nanocellulose is nanodispersed in deionized or demineralized water.

5. The method of any one of claims 1 to 4, wherein the nanodispersion of the nanocellulose in water provided at step A) has a nanocellulose concentration of up to about 5 wt / wt%, preferably up to about 8 wt / wt%, more preferably up to about 10 wt / wt%, and most preferably up to about 15 wt / wt%, based on the total weight of the nanodispersion.

6. The method of any one of claims 1 to 5, further comprising step C) of removing water from the nanodispersion produced at step B).

7. The method of claim 6, wherein step C) is carried by heating above 100°C while mixing or by using a vacuum (e.g. a rotary evaporator) to lower a required temperature for removal, and heating at said temperature for removal.

8. The method of any one of claims 1 to 7, further comprising step D) of producing a nanodispersion of nanocellulose in a second liquid medium using the nanodispersion of nanocellulose in the first liquid medium.

9. The method of claim 8, wherein step D) comprises, while stirring, gradually adding said second liquid medium or one or more components thereof to the nanodispersion of the nanocellulose in the first liquid medium, thereby nanodispersing the nanocellulose in said second liquid medium, wherein the second liquid medium is miscible with the first liquid medium.

10. The method of claim 9, wherein the first liquid medium is a carrying liquid miscible with both water and thesecond liquid medium, wherein the second liquid medium is immiscible with water.11 . The method of claim 9 or 10, wherein the first liquid medium is butanediol, ethyl lactate, or melted polyethylene glycol (PEG) and is a carrying liquid used to achieve nanodispersion in a melted polymer that is immiscible with water, such as polylactide (PLA), polybutylene adipate terephthalate (PBAT), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), or polyhydroxyalkanoates (PHA’s).

12. The method of any one of claims 1 to 11 , further comprising step E) of removing the first liquid medium from the nanodispersion produced at step D).

13. The method of any one of claims 1 to 12, further comprising step F) of repeating step D) or step D) followed by step E) one or more times, each time producing a nanodispersion of nanocellulose in a further liquid medium using a nanodispersion of nanocellulose produced during the immediately preceding step D), wherein each further liquid medium is miscible with the liquid medium of the nanodispersion of nanocellulose produced during the immediately preceding step D).

14. A method for producing a nanodispersion of cellulose nanocrystals in a second liquid medium starting from a nanodispersion of the cellulose nanocrystals in a first liquid medium, the method comprising: i) providing said nanodispersion of the cellulose nanocrystals in the first liquid medium, wherein the first liquid medium is a liquid other than water, and ii) while stirring, gradually adding said second liquid medium or one or more components thereof to the nanodispersion of the cellulose nanocrystals in the first liquid medium, thereby nanodispersing the cellulose nanocrystals in said second liquid medium, wherein the first liquid medium is miscible with the second liquid medium.

15. The method of claim 14, further comprising step Hi) of removing said first liquid medium from the nanodispersion produced at step ii).

16. The method of claim 14 or 15, further comprising step iv) of repeating step ii or step ii followed by step Hi one or more times, each time producing a nanodispersion of nanocellulose in a further liquid medium using a nanodispersion of nanocellulose produced during the immediately preceding step ii), wherein each further liquid medium is miscible with the liquid medium of the nanodispersion of nanocellulose produced during the immediately preceding step ii).

17. The method of any one of claims 1 to 16, wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium is: an aqueous solution, dispersion, or suspension of a charge in water or in a non-aqueous liquid; a non-aqueous liquid including:a solvent, such as methanol, ethanol, dimethylformamide, dimethyl sulfoxide, acrylonitrile, acetone, tetrahydrofuran, 1 ,4-dioxane, ethyl lactate, or glycerol, a melted polymer, composite, or biocomposite polymer, of a carrying liquid, such as a melted solid; a liquid industrial formulation aqueous and non-aqueous); or a liquid reactant (aqueous and non-aqueous), such as a liquid monomer e.g. for condensation polymerization.

18. The method of claim 17, wherein the carrying liquid is ethyl lactate, butanediol, glycerol, dimethylformamide, dimethylsulfoxide, ethylene glycol, or melted polyethylene glycol.

19. The method of claim 17 or 18, wherein the melted polymer is polylactide (PLA), polybutylene adipate terephthalate (PBAT), polyethylene terephlalate (PET), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polylactate-co-hydracrylate (PLH), or polyhydroxyalkanoates (PHA’s).

20. The method of any one of claims 17 to 19, wherein the liquid industrial formulation is a solution, dispersion, or suspension of a charge in a solvent e.g. water or a non-aqueous liquid.

21. The method of any one of claims 17 to 20, wherein the liquid industrial formulation is: a coating such as: a paint, primer, or topcoat; a protective coating, such as a coating offering protection against corrosion, UV, scratches, fingerprints, glare, smudge, or weather; an insulating coating; an easy-to-clean coating; a low-reflection or anti-reflection coating; or a lubricant or friction reduction coating, a sealant, or an adhesive, such as a pressure sensitive adhesive, or an epoxy.

22. The method of any one of claims 17 or 21 , wherein the liquid reactant is a monomer, such as a monomer for a polymerization reaction, for example condensation polymerization.

23. The method of claim 22, wherein the monomer is ethylene glycol, 1 ,4-butandiol (BDO), a mixture of adipic acid, 1 ,4-butanediol and terephthalic acid, a mixture of 1 ,4-butanediol and succinic acid, or lactic acid24. The method of any one of claims 1 to 23, wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion ofnanocellulose in the further liquid medium has a cellulose nanocellulose of up to about 15 wt / wt%, preferably up to about 10 wt / wt%, and more preferably up to about 5 wt / wt%, based on the total weight of the nanodispersion.

25. The method of any one of claims 1 to 24, wherein the nanocellulose bear surface groups such as carboxylate ions and / or sulfate ions.

26. The method of any one of claims 1 to 25, wherein the nanocellulose bear surface carboxylate ions.

27. The method of any one of claims 1 to 26, wherein the nanocellulose is cellulose nanocrystals or cellulose nanofibrils, preferably cellulose nanocrystals.

28. The method of claim 17, wherein the cellulose nanocrystals are from about 2 to about 20 nm in diameter and from about 80 to about 400 nm in length, preferably from about 5 to about 10 nm in diameter and from about 100 to about 250 nm in length.

29. The method of claim 17 or 18, wherein the cellulose nanofibrils are from about 5 to about 100 nm with an aspect ratio > about 30, preferably from about 5 to about 50 nm in diameter and an aspect ratio > about 50.

30. The method of any one of claims 1 to 29, wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium is substantially free of agglomerated nanocellulose.31 . The method of claim 30, wherein the agglomerated nanocellulose is greater than 1000 nm in width and 1000 in length, preferably greater than 500 nm in width and 1000 nm in length, and more preferably greater than 400 nm in in width and 400 nm in length.

32. The method of claim 30 or 31, wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium comprises less than 10 wt / wt% of the agglomerated nanocellulose, preferably less than 5 wt / wt%, preferably less than 1 wt / wt%, based on the total weight to the nanocellulose.

33. The method of any one of claims 30 to 32, wherein the nanodispersion of nanocellulose in the first liquid medium, the nanodispersion of nanocellulose in the second liquid medium, and / or the nanodispersion of nanocellulose in the further liquid medium is free of agglomerated nanocellulose.

34. The method of any one of claims 1 to 33, wherein the adding at step B), D), F), ii) and / or iv) lasts at least 5 minutes, preferably at least 10 minutes, and more preferably at least 15 minutes.

35. The method of any one of claims 1 to 34, wherein an addition rate at step B), D), F), ii) and / or iv) is at most 20% per minute, preferably at most 10% per minute, and most preferably at most 5% per minute.

36. The method of any one of claims 1 to 35, wherein the adding at step B), D), F), ii) and / or iv) is carried out by spraying droplets, or by adding dropwise.

37. The method of any one of claims 1 to 36, wherein the adding at step B), D), F), ii) and / or iv) is carried outgradually, thereby producing a mixture, until the viscosity of the mixture has risen and then started to decrease, then the rest of the adding is carried out at once.

38. The method of claim 36, wherein the adding at step B), D), F), ii) and / or iv) is carried out at such a rate that a decrease in viscosity is observed at least 5 minutes, preferably at least 10 minutes, and more preferably at least 15 minutes after said adding has started.

39. The method of any one of claims 1 to 38, wherein the stirring is carried out at 150-300 rpm, preferably using a paddle- or anchor-type impeller.

40. The method of any one of claims 1 to 39, wherein the first liquid medium is:Liquid Medium A: an aqueous solution, dispersion, or suspension of a charge in water, orLiquid Medium B: a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a non-aqueous liquid, wherein Liquid Medium A and Liquid Medium B are both miscible with water.41 . The method of any one of claims 8 to 39, wherein the second liquid medium is:Liquid Medium A: an aqueous solution, dispersion, or suspension of a charge in water, orLiquid Medium B: a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a non-aqueous liquid, wherein Liquid Medium A and Liquid Medium B are both miscible with the first liquid medium.

42. The method of any one of claims 13 to 39, wherein the further liquid medium is:Liquid Medium A: an aqueous solution, dispersion, or suspension of a charge in water, orLiquid Medium B: a non-aqueous liquid or a solution, dispersion, or suspension of a charge in a non-aqueous liquid, wherein Liquid Medium A and Liquid Medium B are both miscible with a liquid medium of a nanodispersion of nanocellulose produced during the immediately preceding step D) or ii).

43. The method of any one of claims 40 to 42, wherein the first liquid medium in step B), or the second liquid medium in step D) or ii) , or the further liquid medium in step F) or iv) is Liquid Medium A.

44. The method of claim 43, where the adding at step B), D), F), ii) and / or iv) comprises : a) adding part of or all of (preferably all of) the water of the Liquid Medium A and stirring, thereby producing a mixture, and b) while stirring, after step b), gradually adding the charge of the Liquid Medium A to the mixture produced at a), wherein the adding at step b) lasts at least 5 minutes.

45. The method of claim 44, wherein during step a), the water is added all at once.

46. The method of claim 44 or 45, wherein during step b), a viscosity of a mixture to which the charge of the Liquid Medium A is added, increases and then start decreasing, and wherein the adding of the charge of the Liquid Medium A is carried out gradually, until said viscosity start decreasing, then any remaining charge of the Liquid Medium A is added at once or at any other addition rate.

47. The method of any one of claims 43 to 46, wherein the adding at step B), D), F), ii) and / or iv) is carried out in a formulation vessel, and comprises:1 ) adding part of or all of (preferably all of) the water of the Liquid Medium A to the formulation vessel and stirring, thereby producing a mixture of nanocellulose in water,2) while stirring, gradually adding the charge of Liquid Medium A to the formulation vessel until the viscosity of the mixture has risen and then started to decrease, thereby producing a viscous mixture, and3’) storing the viscous mixture for future use, and / or3”) adding any remaining charge of the Liquid Medium A to the formulation vessel, wherein the adding at step 2) lasts at least 5 minutes.

48. The method of any one of claims 43 to 47, wherein the Liquid Medium A is a waterborne industrial product, such as: a waterborne coating, for example : a paint, primer, or topcoat; a protective coating (e.g., offering protection against corrosion, UV, scratches, fingerprints, glare, smudge, or weather); an insulating coating; an easy-to-clean coating; a low-reflection or anti-reflection coating, or a waterborne lubricant or a friction reduction coating, a waterborne sealant, or a waterborne adhesive (e.g. a waterborne epoxy).

49. The method of any one of claims 43 to 48, wherein the Liquid Medium A is a polyurethane dispersion (PUDs), a polyacrylate (PAC) dispersion, a polyurethane / polyacrylate (PU / PAC) hybrid dispersion, a polyester / polyacrylate (PES / PAC) dispersion, a polyisocyanate dispersion, an alkyd dispersion, a polyvinyl alcohol (PVA) dispersion, an epoxy dispersion, a polyol dispersion, a dispersion of copolymers thereof, or amixture thereof; all of which being a one-component (1 K) and two-component (2K) system; all of which optionally comprising crosslinker(s), catalyst(s), cosolvent(s), etc.

50. The method of any one of claims 43 to 49, wherein the Liquid Medium A has a conductivity (ionic strength) > 1000 uS / cm, preferably 1200 uS / cm.51 . The method of any one of claims 43 to 50, wherein the Liquid Medium A is acidic.

52. The method of any one of claims 43 to 51 , wherein the Liquid Medium A has a pH of < 7.

53. The method of any one of claims 43 to 52, wherein the Liquid Medium A has a pH of > 2.

54. The method of any one of claims 43 to 53, wherein the Liquid Medium A is free of cationic surfactant.

55. The method of any one of claims 43 to 54, wherein the Liquid Medium A comprises one or more non-ionic and / or anionic surfactants.

56. The method of any one of claims 40 to 42, wherein the first liquid medium in step B), or the second liquid medium in step D) or ii) , or the further liquid medium in step F) or iv) is Liquid Medium B.

57. The method of claim 56, wherein, during the adding at step B), D), F), ii) and / or iv), the viscosity of a mixture to which the Liquid Medium B is gradually added first increases and then start decreasing, and wherein, when the viscosity starts decreasing, any remaining Liquid Medium B is added at once.

58. The method of claim 56 or 57, wherein the adding at step B), D), F), ii) and / or iv) is carried out in a formulation vessel and comprises:1) while stirring, gradually adding the Liquid Medium B to the formulation vessel, until a mixture is produced and the viscosity of the mixture has risen and then started to decrease, thereby producing a viscous mixture, and2a) storing the viscous mixture for future use, or2b) adding any remaining Liquid Medium B to the formulation vessel, wherein the adding at step 1) lasts at least 5 minutes.

59. The method of any one of claims 56 to 58, wherein the Liquid Medium B is: a carrying liquid such as polyethylene glycol or ethyl lactate; a non-aqueous water-miscible solvent such as methanol, ethanol, dimethylformamide, dimethyl sulfoxide, acrylonitrile, acetone, tetrahydrofuran, 1 ,4-dioxane, or glycerol; a monomer, e.g., for condensation polymerization, such ethylene glycol, 1 ,4-butandiol (BDO), a mixture of adipic acid, 1 ,4-butanediol and terephthalic acid, a mixture of 1 ,4-butanediol and succinic acid, or lactic acid; or a polymer, a composite, or a biocomposite polymer.

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