A dispersion liquid containing nanomaterials, and a preparation method and application thereof

Abstract

The application discloses a dispersion liquid containing nanomaterials and a preparation method and application thereof. The dispersion liquid comprises nanoparticles and a polysaccharide cationic derivative; the polysaccharide cationic derivative is selected from polysaccharide derivatives containing imidazole cations and / or pyridine cations. The dispersion liquid has good dispersibility and can be placed for more than 30 days. The dispersion liquid can be used for functional coating and applied to the fields of hydrophobicity, self-cleaning, photothermal, electrical conductivity, flame retardation and the like, and has important application prospects.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials and functional materials, and relates to a dispersion containing nanomaterials, its preparation method and application. Background Technology

[0002] Nanomaterials possess many unique properties and have found wide applications. However, due to their small size and large specific surface area, nanomaterials are often difficult to disperse uniformly. Preparing nanomaterial dispersions requires the use of large amounts of surfactants to obtain a homogeneous and stable dispersion. However, the use of large amounts of surfactants not only significantly affects the performance of nanomaterials but also causes serious environmental pollution problems. Summary of the Invention

[0003] To achieve the above objectives, the present invention provides the following technical solution:

[0004] A dispersion comprising nanoparticles and a polysaccharide cationic derivative.

[0005] According to an embodiment of the present invention, the nanoparticles include a first nanoparticle and a second nanoparticle.

[0006] According to an embodiment of the present invention, the first nanoparticle and the second nanoparticle are different and are independently selected from at least one of multi-walled carbon nanotubes (MWCNTs), single-walled carbon nanotubes (SWCNTs), halloysite, graphene (G), boron nitride, transition metal carbonitrides (MXene), transition metal borides (MBene), graphdiene, black phosphorus, montmorillonite, talc, two-dimensional layered bimetallic hydroxides (LDH), silicon dioxide, iron tetroxide, titanium dioxide, zinc oxide, and copper oxide.

[0007] According to an embodiment of the present invention, the mass content of the nanoparticles in the dispersion is 0.01-80 wt%, for example, 10 wt%, 20 wt%, 30 wt%, 40 wt%, 50 wt%, or 60 wt%.

[0008] According to an embodiment of the present invention, the mass ratio of the first nanoparticle to the second nanoparticle is (0.1-1):(0.1-1), for example, 1:1.

[0009] According to an embodiment of the present invention, the particle size of the nanoparticles is selected from 10-300nm, for example 10-50nm, 10-100nm, 100-200nm, or for example 20nm, 40nm, 60nm, 80nm, 150nm, 250nm.

[0010] According to an embodiment of the present invention, the dispersion has good dispersibility, for example, it can be stored for more than 30 days.

[0011] According to an embodiment of the present invention, the polysaccharide cationic derivative is selected from polysaccharide derivatives containing imidazole cations and / or pyridine cations.

[0012] According to an embodiment of the present invention, the polysaccharide cationic derivative has the structure shown in Formula I:

[0013]

[0014] in:

[0015] The degree of aggregation (DP) ranges from 100 to 4000, preferably from 100 to 2000, with examples being 100, 220, 500, 600, 650, 810, 1000, 1500, 2000, and 3000.

[0016] A1, A2, and A3 may be the same or different, and are independently selected from H, R1, and cations. or anions And at least one of A1, A2, and A3 is selected from cations. Y is selected from O or NH;

[0017] The cation Selected from at least one or two or more cations having the following structures:

[0018] in Represents the connection site;

[0019] The anion Selected from at least one or two or more of the following anions: Cl - ,Br - F - NO3 - SO4 2- H2PO4 - PO4 3- HPO4 2- C(CN)3 - N(CN)2 - CH3COO - CH3CH2COO - NO3 - NO2 - HCO3 - CO3 2- SO4 2- SO3 2- B4O7 2- (MeO)2PO2 - (EtO)2PO2 -

[0020]

[0021] R1 is selected from At least one of them;

[0022] X is at least one of H, Cl, Br, and I;

[0023] R2, R3, R4, R5, and R6 may be the same or different, and are independently selected from *—H, *—CH2OH, *—Cl, *—Br, *—CHO, *—SH, *—COOH, *—COOCH3, *—COOCH2CH3, *—CH2CH2CN. * -CH3、 * -CH2CH3、 * -CH2CH2CH3, *-CH2CH2CH2CH3, *-CH2CH2OH, *-CH=CH2, *-CH2--CH=CH2, *-CH2-CN, Where * represents a connection site;

[0024] n is selected from 0-10;

[0025] m is selected from 0-10;

[0026] z is selected from 0-10.

[0027] According to an embodiment of the present invention, in the polysaccharide cationic derivative, the polysaccharide backbone is provided by at least one of the following polysaccharides and their derivatives: cellulose, starch, chitosan, and chitin. According to an embodiment of the present invention, the degree of polymerization (DP) of the main chain of the polysaccharide and its derivatives is 100-4000, preferably 100-2000, with exemplary values ​​of 100, 220, 500, 600, 650, 810, 1000, 1500, 2000, and 3000.

[0028] According to an embodiment of the present invention, in the polysaccharide cationic derivative, the cation... The degree of substitution in the polysaccharide and its derivatives is 0.2-3.0, for example 0.5, 1, 1.5, 2, 2.5, 3.

[0029] According to an embodiment of the present invention, in the polysaccharide cationic derivative, the degree of substitution of R1 in the polysaccharide and its derivatives is 0-2.5, for example, 0.01, 0.05, 0.1, 0.5, 1, 1.5, 2.

[0030] According to an embodiment of the present invention, the method for preparing the polysaccharide cationic derivative includes:

[0031] The polysaccharide and its derivatives are dissolved in a first solvent to obtain a polysaccharide solution. An acylation reagent is added to carry out an esterification reaction to obtain a polysaccharide ester. The polysaccharide ester is dissolved in a second solvent, and a cationic reagent is added to carry out a substitution reaction to obtain the cationic derivative of the polysaccharide.

[0032] According to an embodiment of the present invention, the polysaccharide and its derivatives are selected from at least one of cellulose, starch, chitosan, and chitin.

[0033] According to an embodiment of the present invention, the acylation reagent is selected from acyl chlorides, acyl bromides, or carboxylic acids containing an R1 group.

[0034] Preferably, the acylation reagent is selected from acyl chlorides and / or acyl bromides containing R1, where R1 has the meaning as described above.

[0035] According to an embodiment of the present invention, the cationic reagent is selected from imidazoles and / or pyridines containing the following structural units:

[0036]

[0037] Among them, R2, R3, R4, R5, and R6 have the meanings described above.

[0038] According to an embodiment of the present invention, the first solvent is selected from ionic liquids. Preferably, the ionic liquid includes, but is not limited to, at least one of the following ionic liquids: 1-ethyl-3-methylimidazolium chloride ionic liquid, 1-ethyl-3-methylimidazolium bromide ionic liquid, 1-allyl-3-methylimidazolium chloride ionic liquid, 1-allyl-3-methylimidazolium bromide ionic liquid, 1-butyl-3-methylimidazolium chloride ionic liquid, 1-butyl-3-methylimidazolium bromide ionic liquid, 1-ethyl-3-methylimidazolium acetate ionic liquid, and 1-allyl-3-methylimidazolium acetate ionic liquid. The ionic liquids are 1-butyl-3-methylimidazolium acetate, N-ethylpyridine chloride, N-ethylpyridine bromide, 1,3-dimethylimidazolium dimethyl phosphate, 1-ethyl-3-methylimidazolium diethyl phosphate, 3-methylimidazolium carboxylate, N-methylpyridine carboxylate, 1-ethyl-3-methylimidazolium carboxylate, and 1-butyl-3-methylimidazolium carboxylate, preferably 1-allyl-3-methylimidazolium chloride.

[0039] According to an embodiment of the present invention, the second solvent is selected from one, two or more of sulfone solvents and amide solvents, such as one, two or more of dimethyl sulfoxide, N,N-dimethylformamide, and N,N-dimethylacetamide, preferably N,N-dimethylformamide.

[0040] The present invention also provides a method for preparing the above-mentioned dispersion, the method comprising: dissolving a polysaccharide cationic derivative in a solvent to obtain a mixed solution with a mass concentration of 0.01-10%; adding nanoparticles to the mixed solution; dispersing and centrifuging; and taking the supernatant to obtain the dispersion, wherein the polysaccharide cationic derivative and the nanoparticles have the meanings described above.

[0041] According to an embodiment of the present invention, the solvent is selected from at least one of water, dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), chloroform, dichloromethane, 1,2-dichloroethane, acetone, tetrahydrofuran (THF), N-methylpyrrolidone, pyridine, ethanol, methanol, isopropanol, ethyl acetate, butyl acetate, toluene, and methyl ethyl ketone.

[0042] According to an embodiment of the present invention, the dispersion specifically involves ultrasonic dispersion for 1-3 hours.

[0043] The present invention also provides a nanocoating comprising the above-mentioned polysaccharide cationic cellulose derivative and nanoparticles.

[0044] According to an embodiment of the present invention, the functional nanocoating is prepared by means of the above dispersion.

[0045] According to an embodiment of the present invention, the nano-coating is prepared as follows: the above dispersion is sprayed onto a substrate, and after the solvent evaporates, the nano-coating is obtained.

[0046] According to an embodiment of the present invention, the substrate is selected from at least one of glass, plastic, metal, ceramic, wood and other materials.

[0047] According to an embodiment of the present invention, the thickness of the coating is 0.1-1000μm, for example, 10μm, 50μm, 100μm, 200μm, 300μm, 400μm, 500μm, 600μm, 700μm, 800μm, 900μm, or 1000μm.

[0048] The present invention also provides applications of the above-mentioned dispersion and / or nano-coating, preferably in the fields of hydrophobicity, self-cleaning, photothermal and flame retardancy.

[0049] Beneficial effects

[0050] This invention utilizes multiple hydroxyl or amino groups on the polysaccharide backbone to introduce imidazole or pyridine cation structures onto the polysaccharide backbone, thereby enhancing the interaction between the polysaccharide polymer chain and nanoparticles (including π-π interactions and hydrogen bonding interactions), thus promoting the dispersion of nanoparticles. In addition, the dispersed nanoparticles also form interactions with each other, promoting dispersion, ultimately resulting in a dispersion containing different nanoparticles with good dispersibility that can be stored for more than 30 days.

[0051] The dispersion of the present invention can be used in functional coatings, such as hydrophobic, self-cleaning, photothermal and flame retardant coatings, and has important application prospects. Attached Figure Description

[0052] Figure 1 The image shows the 1H NMR spectrum of cellulose butylimidazolium bis(trifluoromethanesulfonyl)imide from Example 4. Instrument: Bruker AV400 NMR spectrometer; solvent: deuterated dimethyl sulfoxide (DMSO-d6).

[0053] Figure 2 This is a photograph of a combustion experiment of the flame-retardant nano-coating in Example 1. Camera: Sony α7.

[0054] Figure 3 The image shows the UV-Vis absorption spectrum of the coating with UV shielding properties in Example 4. Test instrument: Lambda 35, Perkin-Elmer, USA.

[0055] Figure 4 These are photothermal images of the nano-coating with electrothermal properties in Example 3 under different light intensities. Testing instrument: FLIRA300 (FLIR Systems).

[0056] Figure 5 Photographs showing the contact angle test results of the superhydrophobic nanocoating in Example 2. Test instrument: DSA-100, Krüss, Germany.

[0057] Figure 6 The conductivity of the superhydrophobic coating with conductive properties in Example 2 is shown. Test instrument: ST2263, Suzhou Lattice Electronics Co., Ltd.

[0058] Figure 7 This is a photograph showing the dispersion stability of carbon nanotubes and graphene in Example 2. Camera used: Sony α7. Detailed Implementation

[0059] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0060] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0061] Example 1

[0062] The method for preparing the dispersion is as follows:

[0063] (1) Preparation of polysaccharide ester: Weigh 0.6g of cellulose (degree of polymerization 650) and dissolve it in 9.4g of 1-allyl-3-methylimidazolium chloride ionic liquid (AmimCl). Add 1.2g of 2-chloropropionyl chloride and react at 40℃ for 3h. After the reaction is completed, pour it into ethanol, precipitate, wash and dry to obtain cellulose 2-chloropropionate.

[0064] (2) Preparation of polysaccharide cationic derivatives: Weigh 1g of the prepared cellulose 2-chloropropionate, dissolve it in 30mL of DMF, add 2g of 1-allyl imidazole, react at 80℃ for 48h, pour into acetone, and after precipitation, washing and drying, obtain cellulose allyl imidazole chloride (Cam).

[0065] In this embodiment, the degree of substitution of R1 in cellulose propylimidazolium chloride is 1.5, and the degree of substitution of the cation is 1.4.

[0066] (3) Preparation of dispersion: Weigh 0.1g of cellulose allyl imidazole chloride and dissolve it in water to obtain a mixed solution with a mass fraction of 0.1%. Add 0.4g of boron nitride (BN, particle size range of 80-200nm) and 0.4g of nano zinc oxide (ZnO, particle size range of 30-80nm) to the above mixed solution, sonicate for 1h, centrifuge and take the supernatant to obtain BN / ZnO / Cam aqueous dispersion. The total mass fraction of boron nitride and nano zinc oxide in the dispersion is 50wt%.

[0067] (4) Coating preparation: The BN / ZnO / Cam aqueous dispersion is coated on the plastic and dried to obtain a transparent thermally conductive and flame-retardant coating with a thickness of 10-300μm. The coating thickness obtained in this embodiment is 10μm.

[0068] A combustion experiment was conducted on the thermally conductive and flame-retardant coating of this embodiment, as follows: the plastic coated with the coating was ignited with an alcohol lamp. After ignition, the flame was removed. After self-extinguishing, the coating was reignited with an alcohol lamp. After ignition, the coating was removed from the flame.

[0069] Figure 2 The image shows a combustion experiment photograph of the nano-coating prepared in Example 1.

[0070] Example 2

[0071] The method for preparing the dispersion is as follows:

[0072] (1) Preparation of polysaccharide ester: 0.6 g of starch (degree of polymerization 2000) was added to 9.4 g of ionic liquid 1-allyl-3-methylimidazolium chloride (AmimCl), and stirred vigorously at 80 °C for 1 h to dissolve, obtaining a starch / AmimCl solution with a mass fraction of 6%. After cooling to 0 °C, 1.4 g of 2-bromopropionyl bromide was added, and the reaction was carried out at 40 °C for 3 h. After the reaction was completed, ethanol was added to precipitate the precipitate, and the solution was filtered, washed, and dried to obtain starch 2-bromopropionate.

[0073] (2) Preparation of polysaccharide cationic derivative: Weigh 0.50g of starch 2-bromopropionate obtained above, dissolve it in 15mL of DMF, add 2.80g of 1-methylimidazole, react at 80℃ for 24h, pour it into acetone after the reaction, and obtain starch methylimidazole bromide (Smm) after precipitation, washing and drying.

[0074] Dissolve 1g of starch methylimidazolium bromide in water, add 1.7g of sodium bis(trifluoromethanesulfonyl)imide, stir for 0.5h, filter, wash and dry to obtain starch methylimidazolium bis(trifluoromethanesulfonyl)imide (SmmT).

[0075] In this embodiment, the degree of substitution of R1 in the starch methylimidazolium bis(trifluoromethanesulfonyl)imide salt is 3.0, and the degree of substitution of the cation is 2.8.

[0076] (3) Preparation of dispersion: Weigh starch methylimidazolium bis(trifluoromethanesulfonyl)imide salt and dissolve it in DMF to obtain a mixed solution with a mass fraction of 0.01%. Add multi-arm carbon nanotubes (MWCNTs, particle size range of 10-30 nm) and graphene (G, particle size range of 100-200 nm) to the above mixed solution at a mass ratio of 1:1 to prepare solutions with a total concentration of graphene and multi-arm carbon nanotubes of 20 wt%, 40 wt%, 70 wt%, and 80 wt%, respectively. Disperse the solution by ultrasonication for 1 h, centrifuge and take the supernatant to obtain MWCNT / G / SmmT / DMF dispersion. The total mass fraction of multi-arm carbon nanotubes and graphene in the dispersion is 10 wt%, 30 wt%, 50 wt%, and 60 wt%.

[0077] (4) Coating preparation: The above-mentioned MWCNT / G / SmmT / DMF dispersions of different concentrations are coated on plastic and dried to obtain a superhydrophobic conductive coating with a thickness of 10-200 μm. The coating thickness in this embodiment is 100 μm.

[0078] The superhydrophobic conductive coating of this embodiment was tested for its contact angle and conductivity. The test process is as follows:

[0079] (a) Contact angle: 5 μl of water droplets were dropped onto the coating. After the water droplets stabilized, the contact angle was calculated by taking pictures (testing 5 different locations).

[0080] (b) Conductivity: Place the coating on the four-probe instrument, pull down and press the probe firmly, and record the data after the reading stabilizes.

[0081] Figure 5 The image shows a contact angle test photograph of the superhydrophobic conductive coating in Example 2 (total concentration of graphene and multi-arm carbon nanotubes is 30 wt%). Figure 6 The conductivity is the electrical conductivity of the superhydrophobic conductive coating in Example 2.

[0082] Example 3

[0083] The method for preparing the dispersion is as follows:

[0084] (1) Preparation of polysaccharide ester: Weigh 2g of chitosan (degree of polymerization of 100) and dissolve it in 48g of 1-ethyl-3-methylimidazolium acetate ionic liquid (EmimAc). Add 3.20g of 2-chloropropionyl chloride and react at 40℃ for 1.5h. After the reaction is completed, pour it into ethanol, precipitate, wash and dry to obtain chitosan 2-chloropropionyl ester.

[0085] (2) Preparation of polysaccharide cationic derivative: Weigh 1.0g of the chitosan 2-chloropropionyl ester prepared above, dissolve it in 15mL of N,N-dimethylformamide, add 4g of 1-butylimidazolium, react at 80℃ for 24h, pour it into acetone after the reaction, and obtain chitosan butylimidazolium chloride (Chbm) after precipitation, washing and drying.

[0086] Weigh 1.0 g of chitosan butylimidazolium chloride and dissolve it in 20 mL of water. Add 5 wt% lithium hexafluorophosphate (LiPF6) aqueous solution, stir for 4 h, filter, wash with water, and dry to obtain chitosan butylimidazolium hexafluorophosphate (ChbmP).

[0087] In this embodiment, the degree of substitution of R1 in chitosan butylimidazolium hexafluorophosphate is 2.5, and the degree of substitution of the cation is 2.3.

[0088] (3) Preparation of dispersion: Weigh 0.1g of chitosan butylimidazolium hexafluorophosphate and dissolve it in N,N-dimethylformamide to obtain a mixed solution with a mass fraction of 0.01%. Add 0.3g of MXene (particle size range of 100-200nm) and 0.3g of multi-arm carbon nanotubes (MWCNT, particle size range of 10-30nm) to the above mixed solution, sonicate for 1h, centrifuge and take the supernatant to obtain MXene / MWCNT / ChbmP / DMF dispersion. The total mass fraction of MXene and multi-arm carbon nanotubes in the dispersion is 40wt%.

[0089] (4) Coating preparation: The MXene / MWCNT / ChbmP / DMF dispersion is coated on glass and dried to obtain a nano-coating with photothermal and electrothermal properties and all-weather anti-icing properties. The thickness can be 10-1000μm. In this embodiment, the coating thickness is 500μm.

[0090] The nano-coating of this embodiment was tested for its photothermal, electrothermal, and all-weather anti-icing properties, specifically as follows: The coating was placed under 0.5 solar intensity and one solar intensity, and the temperature change was recorded using an infrared thermal imager to obtain the temperature changes under different light intensities. The coating was placed in the middle of circuits with different voltages to form a circuit, and the temperature change was recorded using an infrared thermal imager to obtain the temperature changes under different voltages. First, ice was spread all over the coating, and the ice melting process was recorded with a camera under one solar intensity and under different voltages.

[0091] Figure 4 These are photothermal images of the nano-coating with electrothermal properties in Example 3 under different light intensities.

[0092] Example 4

[0093] The method for preparing the dispersion is as follows:

[0094] (1) Preparation of polysaccharide ester: Weigh 2.0g of cellulose (degree of polymerization of 220) and dissolve it in 48.0g of 1-butyl-3-methylimidazolium chloride ionic liquid (BmimCl). Add 2.3g of chloroacetyl chloride and react at 40℃ for 1.5h. After the reaction is completed, pour it into ethanol, and after precipitation, washing and drying, cellulose chloroacetate is obtained.

[0095] (2) Preparation of polysaccharide cationic derivatives: Weigh 0.5g of the cellulose chloroacetate obtained above, dissolve it in 15mL of DMF, add 2.7g of 1-hydroxyethyl imidazole, react at 80℃ for 24h, pour into acetone, and after precipitation, washing and drying, obtain cellulose hydroxyimidazolium chloride (COHm).

[0096] Dissolve 1g of cellulose hydroxyimidazolium chloride in water, add 1.6g of sodium bis(trifluoromethanesulfonyl)imide, stir for 0.5h, filter, wash and dry to obtain cellulose hydroxyimidazolium bis(trifluoromethanesulfonyl)imide (COHmT).

[0097] Figure 1 The image shows the 1H NMR spectrum of the cellulose butylimidazolium bis(trifluoromethanesulfonyl)imide prepared in Example 4. Testing instrument: Bruker AV400 NMR spectrometer; solvent: deuterated dimethyl sulfoxide (DMSO-d6). In this example, the degree of substitution of R1 in the cellulose hydroxyimidazolium bis(trifluoromethanesulfonyl)imide salt was 2.0, and the degree of substitution of the cation was 1.7.

[0098] (3) Preparation of dispersion: Weigh 0.1 g of cellulose hydroxyimidazolium bis(trifluoromethanesulfonyl)imide salt and dissolve it in DMF / ethyl acetate (EA) (DMF:EA = 5:95, v / v) to obtain a mixed solution with a mass fraction of 0.01%. Add 0.5 g of titanium dioxide (particle size range 15-50 nm) and 0.5 g of boron nitride (particle size range 80-200 nm) to the above mixed solution, sonicate for 1 h, centrifuge and take the supernatant to obtain titanium dioxide / boron nitride / COHmT / DMF / EA dispersion. The total mass fraction of titanium dioxide and boron nitride in the dispersion is 30 wt%.

[0099] (4) Coating preparation: Titanium dioxide / boron nitride / COHmT / DMF / EA dispersion is coated on glass and dried to obtain a transparent nano-coating with UV resistance. The thickness can be 10-1000μm. In this embodiment, the coating thickness is 100μm.

[0100] The nano-coating of this embodiment was tested for its UV resistance (i.e., UV shielding performance), specifically as follows: The coated glass was placed in a UV-Vis absorption spectrometer, and light with a wavelength of 200-800 nm was transmitted through the coating to obtain the transmittance of light with a wavelength of 200-800 nm. Simultaneously, the coated glass was placed in the UV anti-counterfeiting area of ​​a 100 RMB banknote, and irradiated with a 365 nm UV lamp; the anti-counterfeiting area was then blocked.

[0101] Figure 3 The image shows the UV-Vis absorption spectrum of the coating with UV shielding properties in Example 4.

[0102] Example 5

[0103] The method for preparing the dispersion is as follows:

[0104] (1) Preparation of polysaccharide ester: 0.5 g of chitosan (degree of polymerization 200) was weighed and added to 9.5 g of 1-allyl-3-methylimidazolium bromide ionic liquid (AmimBr). The mixture was stirred at 100 °C for 2 h to obtain a 5% (w / w) chitosan AmimBr solution. The solution was cooled to 0 °C, and then 1.5 g of 2-chloropropionyl chloride was added. The mixture was reacted at 40 °C for 3 h. After the reaction was completed, ethanol was added to precipitate the precipitate. The precipitate was filtered, washed, and dried to obtain chitosan 2-chloropropionate.

[0105] (2) Preparation of polysaccharide cationic derivatives: Weigh 0.50g of the prepared chitosan 2-chloropropionyl ester, dissolve it in 15mL of N,N-dimethylformamide, add 4.10g of 1-allyl imidazole, react at 80℃ for 24h, pour it into acetone after the reaction, and obtain chitosan allyl imidazole chloride (ChAm) after precipitation, washing and drying.

[0106] 1.0 g of chitosan allyl imidazole chloride was dissolved in water, and 2.5 g of sodium bis(trifluoromethanesulfonyl)imide was added. The mixture was stirred for 0.5 h, filtered, washed, and dried to obtain chitosan allyl imidazole bis(trifluoromethanesulfonyl)imide (ChAmT).

[0107] In this embodiment, the degree of substitution of R1 in chitosan allyl imidazole bis(trifluoromethanesulfonyl)imide salt is 1.8, and the degree of substitution of the cation is 1.6.

[0108] (3) Preparation of dispersion: Weigh 0.1g of chitosan allyl imidazole bis(trifluoromethanesulfonyl)imide salt and dissolve it in tetrahydrofuran (THF) to obtain a mixed solution with a mass fraction of 0.01%. Add 0.2g of iron oxide nanoparticles (particle size range of 20-300nm) and 0.2g of zinc oxide nanorods (particle size range of 30-80nm) to the above mixed solution, sonicate for 1h, centrifuge and take the supernatant to obtain iron oxide / zinc oxide / ChAmT / THF dispersion. The total mass fraction of iron oxide nanoparticles and zinc oxide nanorods in the dispersion is 35wt%.

[0109] (4) Coating preparation: The iron oxide / zinc oxide / ChAmT / THF dispersion is coated on the iron plate and dried to obtain an anti-corrosion nano coating with a thickness of 10-1000μm. The coating thickness in this embodiment is 100μm.

[0110] The nano-coating of this embodiment was tested for its corrosion resistance as follows: Coated and uncoated iron sheets were prepared and placed in a saturated sodium chloride / potassium carbonate aqueous solution. After 7 days, the surface corrosion was observed. The coated iron sheet showed a significant reduction in corrosion.

[0111] Comparative Example 1

[0112] The method for preparing the dispersion in this comparative example is basically the same as in Example 1, except that cellulose allyl imidazole chloride is not added, and the total mass fraction of boron nitride and nano zinc oxide in the dispersion is 0.1 wt%.

[0113] The coating preparation method is the same as in Example 1.

[0114] Comparative Example 2

[0115] The method for preparing the dispersion in this comparative example is basically the same as in Example 1, except that sodium carboxymethyl cellulose, a polysaccharide anionic derivative, is added. In the dispersion of this comparative example, the total mass fraction of boron nitride and nano-zinc oxide is 1 wt%.

[0116] The coating preparation method is the same as in Example 1.

[0117] Comparative Example 3

[0118] The method for preparing the dispersion in this comparative example is basically the same as in Example 2, except that starch methylimidazolium bis(trifluoromethanesulfonyl)imide salt is not added to the mixed solution, and only graphene (10 wt% concentration) is added to the mixed solution. The dispersion obtained in this comparative example contains 5 wt% graphene.

[0119] The coating preparation method is the same as in Example 2.

[0120] Comparative Example 4

[0121] The method for preparing the dispersion in this comparative example is basically the same as in Example 1, except that in step (2), 1-allylimidazolium is replaced with tributylphosphine when preparing the polysaccharide cationic derivative. In the dispersion of this comparative example, the total mass fraction of boron nitride and nano zinc oxide is 3 wt%.

[0122] Test Example 1

[0123] Take the dispersions prepared in Examples 1-5 above and test their stability. The specific methods are as follows: centrifuge at 1000 rpm for 5 min or let stand for 30 days and observe the sedimentation of nanomaterials in the dispersion.

[0124] The stability of the dispersion in Example 2 and the stability of the dispersion in Comparative Example 3 are as follows: Figure 7 As shown, it can be seen that adding the polysaccharide cationic derivative of the present invention is more conducive to preparing a stable dispersion with a high mass fraction.

[0125] Because the concentration of nanoparticles in the dispersions obtained in Comparative Examples 1-4 is low, the uniformity of the coatings prepared from them is poor.

[0126] The exemplary embodiments of the present invention have been described above. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A dispersion, characterized in that, The dispersion comprises nanoparticles and polysaccharide cationic derivatives; the mass content of the nanoparticles in the dispersion is 10-80 wt%. The method for preparing the dispersion includes: dissolving a polysaccharide cationic derivative in a solvent to obtain a mixed solution with a mass concentration of 0.01-10%; adding nanoparticles to the mixed solution; dispersing; centrifuging; and taking the supernatant to obtain the dispersion. The polysaccharide cationic derivative is selected from polysaccharide derivatives containing imidazole cations; the polysaccharide cationic derivative has the structure shown in Formula I: Equation I The degree of aggregation (DP) ranges from 100 to 4000. A1, A2, and A3 may be the same or different, and are independently selected from H, R1, and cations. And at least one of A1, A2, and A3 is selected from cations. Y is selected from O or NH; The cation The degree of substitution in the polysaccharide derivative is 1-3.0; The cation Selected from one of the following imidazole cations having the following structure: ,in Represents the connection site; R1 is selected from , X is at least one of H, Cl, Br, and I; R2, R3, R4, and R5 are selected from * —H, where * represents a connection site; n is selected from 1-10; The nanoparticles include a first nanoparticle and a second nanoparticle, wherein the mass ratio of the first nanoparticle to the second nanoparticle is 0.1~1:0.1~1; the first nanoparticle and the second nanoparticle are different from each other and are independently selected from at least one of multi-walled carbon nanotubes, single-walled carbon nanotubes, graphene, boron nitride, transition metal carbonitrides, iron tetroxide, titanium dioxide, and zinc oxide.

2. The dispersion according to claim 1, characterized in that, The particle size of the nanoparticles is selected from 10-300 nm.

3. The dispersion according to claim 1 or 2, characterized in that, The polysaccharide cationic derivative is cellulose allyl imidazolium chloride, in Formula I, where the degree of substitution of R1 is 1.5 and the degree of substitution of the cation is 1.4; or, The polysaccharide cationic derivative is starch methylimidazolium bis(trifluoromethanesulfonyl)imide salt, in Formula I, the degree of substitution of R1 is 3.0, and the degree of substitution of the cation is 2.8; or, The polysaccharide cationic derivative is chitosan butylimidazolium hexafluorophosphate, in Formula I, where the degree of substitution of R1 is 2.5 and the degree of substitution of the cation is 2.3; or, The polysaccharide cationic derivative is cellulose hydroxyimidazolium bis(trifluoromethanesulfonyl)imide salt, in Formula I, where the degree of substitution of R1 is 2.0 and the degree of substitution of the cation is 1.7; or, The polysaccharide cationic derivative is chitosan allyl imidazole bis(trifluoromethanesulfonyl)imide salt, where the degree of substitution of R1 in Formula I is 1.8 and the degree of substitution of the cation is 1.

6.

4. The dispersion according to claim 1, characterized in that, The preparation method of the polysaccharide cationic derivative includes: Polysaccharides and their derivatives are dissolved in a first solvent to obtain a solution of polysaccharides and their derivatives. An acylation reagent is added to carry out an esterification reaction to obtain an ester of the polysaccharide and its derivatives. The ester of the polysaccharide and its derivatives is dissolved in a second solvent, and a cationic reagent is added to carry out a substitution reaction to obtain the cationic derivative of the polysaccharide.

5. The dispersion according to claim 4, characterized in that, The polysaccharide and its derivatives are selected from at least one of cellulose, starch, chitosan, and chitin; The acylation reagent is selected from acyl chlorides, acyl bromides, or carboxylic acids containing an R1 group; The cationic reagent is selected from one of 1-allylimidazole, 1-methylimidazole, 1-butylimidazole, and 1-hydroxyethylimidazole; The first solvent is selected from ionic liquids; The second solvent is selected from one or both of sulfone solvents and amide solvents.

6. The dispersion according to claim 4, characterized in that, The acylation reagent is selected from acyl chlorides and / or acyl bromides containing R1.

7. The method for preparing the dispersion according to any one of claims 1-6, characterized in that, The preparation method includes: dissolving the polysaccharide cationic derivative in a solvent to obtain a mixed solution with a mass concentration of 0.01-10%; adding nanoparticles to the mixed solution; dispersing and centrifuging; and taking the supernatant to obtain the dispersion.

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