Coating containing polycation liquid dispersant and preparation method thereof

Abstract

The invention belongs to the technical field of coatings, and particularly relates to a coating containing a polycation liquid dispersant and a preparation method of the coating. The coating containing the polycation liquid dispersant is prepared from the following components in percentage by mass: 20 to 22 weight percent of carbon nanomaterial dispersion liquid and 40 to 60 weight percent of film-forming resin. The carbon nanomaterial dispersion liquid contains a polycation liquid dispersant, a carbon nanomaterial and a solvent, the polycation liquid dispersant is generated by reversible addition-fragmentation chain transfer polymerization (RAFT) of an imidazolyl ionic liquid monomer and a methacrylate compound, the number-average molecular weight Mn of the polymer is 30-80 kDa, the ionic liquid unit is greater than or equal to 80%, and the Tg is 120-150 DEG C. The carbon nanomaterial dispersion liquid provided by the invention can be compounded with various film-forming resins to prepare a coating with electric conduction, heat conduction or antistatic functions and the like, and has a wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of coating technology, specifically relating to a coating containing a polycationic liquid dispersant and its preparation method. Background Technology

[0002] Since its discovery in 1991, carbon nanotubes (CNTs) have become a core member of the nanomaterials family. Their preparation technology has undergone a leap from "gram-level laboratory" to "ton-level industrialization." Currently, more than 90% of the production capacity comes from chemical vapor deposition (CVD), which allows for continuous growth simply by introducing carbon sources such as methane / ethanol onto the catalyst surface, with a single furnace producing hundreds of kilograms per day.

[0003] Based on the number of layers, CNTs can be classified into: single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), and arrayed / oriented CNTs. SWCNTs typically have a diameter of 0.4-3 nm and exhibit metallic or semiconductor chirality, with a specific surface area greater than 1300 m². 2 / g, carrier mobility can reach 10 5 cm 2 / V•s, MWCNT conductivity exceeds 10 6 S / m is mainly used in high-end electronic devices, but its manufacturing cost is high. MWCNT, with a diameter in the range of 2-100 nm, is composed of several to dozens of coaxially nested layers of graphene. It has outstanding mechanical strength and is easy to scale up, making it the mainstream choice for conductive pastes and composite materials.

[0004] CNTs can achieve an axial thermal conductivity of 3000 W / m•K, a tensile strength exceeding 100 GPa, and an elastic modulus of ≈1 TPa. However, due to their high aspect ratio (>1000) and large specific surface area, CNTs exhibit van der Waals forces as high as 0.95 eV / nm. These massive van der Waals forces and strong π-π interactions make them highly prone to aggregation, forming irreversible agglomerates that are difficult to disperse uniformly in solvents. This results in an increased percolation threshold, incomplete conductive networks, and localized stress concentration in the composite material, ultimately leading to a performance improvement far below the theoretical value and severely limiting its application.

[0005] Currently, the mainstream dispersion methods include physical and chemical methods. Physical methods mainly involve dispersion through ball milling / sand milling, high-pressure microfluidics, and ultrasound.

[0006] Ball milling / sand milling dispersion possesses extremely strong shearing force, but it leads to a significant reduction in CNT length, decreasing by approximately 90%, and causing a 30-50% drop in conductivity. High-pressure microfluidic methods can break down and disperse CNT bundles to 20 nm through multiple cycles, but the initial investment in equipment is high (>2 million RMB), and repeated cycles can easily introduce metal contamination. Ultrasonic dispersion utilizes the cavitation effect generated by ultrasound to rapidly peel away the tube bundle, thus dispersing CNTs, but the local high temperature and pressure can easily cut off CNTs, and it is only suitable for small volumes (<20 mL), with poor uniformity of the cavitation field after scaling up.

[0007] Chemical methods primarily involve the dispersion of CNTs through strong acid oxidation, in-situ growth, and surfactants. Strong acid oxidation, in particular, involves grafting functional groups such as -COOH and -OH onto surface defects of CNTs to increase their hydrophilicity and facilitate dispersion. However, surface modification can lead to variations in the hydrophilicity of CNTs. 2 The structure was damaged, causing its electrical conductivity to decrease and generating a large amount of acidic waste liquid, which is difficult to treat.

[0008] In-situ growth controls the structure and dispersion of CNTs from the source, directly growing CNTs on the matrix surface using CVD to achieve directional alignment. However, the process temperature exceeds 600℃, which does not match the polymer processing window, and the resulting composite material has low density, making it difficult to apply widely.

[0009] Surfactants achieve dispersion by adsorbing CNTs at their hydrophobic ends and providing electrostatic steric hindrance at their hydrophilic ends, utilizing π-π stacking and electrostatic interactions in synergy. Commonly used dispersants include SDS, CTAB, ionic liquids, and conjugated polymers, but they generally suffer from problems such as low dispersion efficiency, poor thermal stability, poor compatibility with the matrix, or decreased conductivity. The adsorbed layer formed by CNTs and surfactants is prone to desorption in high-temperature curing or polar solvents and may re-aggregate.

[0010] Therefore, since physical dispersion can cause CNT damage and performance degradation, while chemical dispersion can cause pollution and poor dispersion stability, the industry urgently needs a new dispersion technology that is "efficient, low-damage, and adaptable to a wide range of temperatures and solvents".

[0011] Polyionic liquids (PILs) combine the high conductivity of ionic liquids with the processability of polymers, and have attracted attention in the field of carbon nanomaterial dispersion in recent years. Ionic liquids themselves exhibit strong π-π conjugation on CNT surfaces, allowing them to insert into the interstices of the tube bundles to reduce van der Waals forces. After polymerization, PILs possess tunable polarity, high charge density, thermal stability, and post-functionalization capabilities. The compatibility of PILs with solvents / resins can be determined by the side chain length and anion type, and each repeating unit contains a cationic center, resulting in better anti-agglomeration ability than traditional surfactants. The anions in PILs are also easily replaceable, allowing for easy hydrophilic-hydrophobic switching and the acquisition of dispersants covering multiple systems such as water, NMP, alcohols, esters, and hydrocarbons. However, existing PIL synthesis routes are complex, have low yields, and struggle to simultaneously achieve good dispersibility, thermal stability, and mechanical properties. Summary of the Invention

[0012] To address the shortcomings of existing technologies, this invention provides a polycationic liquid dispersant (IL-R, PIL, PIL-co-PMMA) that is easy to synthesize and has excellent dispersibility, as well as the application of this polymer in dispersing graphene (Gr), single-walled carbon nanotubes (SWCNTs), and multi-walled carbon nanotubes (MWCNTs).

[0013] This invention provides a cationic monomer for a polycationic liquid dispersant, as shown in compound (I): Among them, anion R - Including but not limited to halide anions, which include but are not limited to fluoride ions (F... - ), chloride ions (Cl) - ), bromide ions (Br) - ), iodide ions (I - R1 is selected from methyl or butyl, preferably methyl; R2 is selected from hydrogen or methyl, preferably hydrogen.

[0014] The present invention provides a method for preparing the cationic monomer shown in formula (I), the steps of which include: mixing 11-haloundecyl acrylate, imidazole compound and polymerization inhibitor under an inert atmosphere or a nitrogen atmosphere, reacting at 40±2℃ to obtain the compound of formula (I).

[0015] Under the inert atmosphere or nitrogen atmosphere, the gas flow rate is ≥50 mL / min, and the inert gas includes, but is not limited to, any one or any combination of helium, neon, argon, krypton, xenon, and radon.

[0016] The molar ratio of the 11-haloundecyl acrylate to the imidazole compound is 1:1-2, preferably 1:1-1.5, and more preferably 1:1.2; the amount of polymerization inhibitor is 0.01-0.02 wt% of the total mass of the 11-haloundecyl acrylate and the imidazole compound, preferably 0.01 wt%; in the 11-haloundecyl acrylate, the substituted halogen atom is selected from fluorine, chlorine, bromine, and iodine atoms, and more preferably bromine; the imidazole compound is selected from any one of 1-methylimidazolium, 1,2-dimethylimidazolium, and N-butylimidazolium, preferably 1-methylimidazolium; the polymerization inhibitor is selected from any one of butylated hydroxytoluene (BHT) and 4-Hydroxy-TEMPO, preferably butylated hydroxytoluene (BHT).

[0017] Further, the reaction was carried out at 40±2℃ for 24-48 h, with stirring during the reaction at a speed of 200-400 rpm. After the reaction was completed, the mixture was washed three times with diethyl ether, with a volume ratio of diethyl ether to reaction solution of 2:1 each time. Then, it was diluted with dichloromethane to a solid content of 20-30 wt%, evaporated at room temperature for 24 h, and dried under vacuum at 45 ℃ to obtain compound (I). The halogen content in compound (I) is ≤0.5 wt%.

[0018] The preparation of the 11-haloundecyl acrylate includes: adding acryloyl chloride to an organic solvent containing 11-haloundecyl alcohol in a low-temperature environment under the action of an acid-binding agent, and reacting to obtain 11-haloundecyl acrylate.

[0019] In the reaction system, the molar ratio of 11-haloundecaneol to acryloyl chloride is 1:0.9-2, preferably 1:1-1.5, and more preferably 1:1.2; the molar ratio of 11-haloundecaneol to the acid-binding agent is 1:0.9-2, preferably 1:1-1.5, and more preferably 1:1.2; the molar ratio of 11-haloundecaneol to the organic solvent is 0.1-1 mmol:1 mL, preferably 0.3-0.6 mmol:1 mL, and more preferably 0.5 mmol:1 mL. mmol:1mL; the substituted halogen atom in the 11-haloundecanool is selected from fluorine, chlorine, bromine, and iodine atoms, and is more preferably bromine; the acid-binding agent is selected from any one or any combination of triethylamine, pyridine, 4-dimethylaminopyridine, diisopropylethylamine, potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide, and is preferably triethylamine; the organic solvent is selected from any one or any combination of tetrahydrofuran (THF), dichloromethane (DCM), acetonitrile, N,N-dimethylformamide (DMF), ethyl acetate, and acetone, and is preferably THF.

[0020] Further, acryloyl chloride was added to an organic solvent containing 11-haloundecaneol at 0℃-5℃, and the reaction was carried out at room temperature to obtain 11-haloundecyl acrylate. Even further, acryloyl chloride was added to an organic solvent containing 11-haloundecaneol at 0℃-5℃ for 0.5-1 h, and the reaction was allowed to mature at 25℃ for 24-48 h to obtain 11-haloundecyl acrylate. The reaction was carried out with stirring at a speed of 200-400 rpm.

[0021] Further, after the reaction was completed, the precipitate was removed by filtration, and the filtrate was washed and extracted three times with sodium bicarbonate aqueous solution (2%). The upper oil phase was collected, dried with anhydrous sodium sulfate, and the dried oil phase was rotary evaporated to remove THF. Then, column chromatography (petroleum ether: ethyl acetate = 50:1) was performed to purify and obtain 11-haloundecyl acrylate.

[0022] The cationic monomer for the polycationic liquid dispersant provided above can be used to prepare cationic liquid dispersants or to prepare carbon nanomaterial dispersions.

[0023] This invention provides a polycationic liquid dispersant, prepared by self-polymerization of a compound of formula (I); or prepared by reversible addition-fragmentation chain transfer polymerization of a compound of formula (I) and a methacrylate compound; the compound of formula (I) is shown below: Among them, anion R - Including but not limited to halide anions, which include but are not limited to fluoride ions (F... - ), chloride ions (Cl) - ), bromide ions (Br) - ), iodide ions (I - R1 is selected from methyl or butyl, preferably methyl; R2 is selected from hydrogen or methyl, preferably hydrogen.

[0024] The mass ratio of the compound of formula (I) to the methacrylate compound is 5-6.5:1, preferably 5.5-6:1, and more preferably 5.6-5.7:1. The methacrylate compound includes, but is not limited to, methyl methacrylate (MMA), isobornyl methacrylate (IBOMA), and dimethylamine ethyl methacrylate (DMAEMA), with methyl methacrylate being the most preferred.

[0025] In the process of generating a polycationic liquid dispersant by reversible addition-fragmentation chain transfer polymerization of the compound of formula (I) and methacrylate compounds, a solvent, a chain transfer agent, and an initiator are also added. The mass ratio of the solvent to the compound of formula (I) is 9.5-11.5:1, preferably 10-11:1, and more preferably 10.5-10.6:1. The solvent includes, but is not limited to, any one or any combination of dimethylformamide (DMF), n-butanol, methanol, ethanol, isopropanol, ethyl acetate, toluene, butyl acetate, and anisole, preferably dimethylformamide. The mass ratio of the chain transfer agent to the initiator is 2-4:1, preferably 3:1. The mass ratio of the chain transfer agent to the compound of formula (I) is 1:1. The chain transfer agent is 40-143, preferably 1:141-142, more preferably 1:1141.5-142, and even more preferably 1:141.6-141.7; the chain transfer agent includes, but is not limited to, any one or any combination of 2-cyano-2-propyldodecylthionaphthalene ester (CPDN), S-thiobenzoyl mercaptoacetic acid (BTTAA), and trithiocarbonate (TTC), preferably 2-cyano-2-propyldodecylthionaphthalene ester (CPDN); the initiator includes, but is not limited to, any one or any combination of azobisisobutyronitrile (AIBN), azobisisobutyronitrile valerate (ACPA), persulfate, organic peroxide, and hydroperoxide, preferably azobisisobutyronitrile (AIBN).

[0026] During the process of generating a polycationic liquid dispersant by reversible addition-fragmentation chain transfer polymerization of the compound of formula (Ⅰ) and methacrylate compounds, the temperature is 60℃-70℃, the time is 12-24h, and the stirring speed is 400-500rpm.

[0027] The dispersibility of the polycationic liquid dispersant generated by the reversible addition-fragmentation chain transfer polymerization of the compound of formula (I) and methacrylate compounds. ≤1.3.

[0028] This invention provides a method for preparing a polycationic liquid dispersant, comprising the following steps: mixing a compound of formula (I), an initiator, and a solvent; freezing with liquid nitrogen; evacuating the system; circulating an inert gas or nitrogen gas; and self-polymerizing at 60°C-70°C to generate the polycationic liquid dispersant; or... The compound of formula (Ⅰ), methacrylate compound, chain transfer agent, initiator and solvent are mixed and frozen with liquid nitrogen, vacuumed, and filled with inert gas or nitrogen circulation. A reversible addition-fragmentation chain transfer polymerization reaction is carried out at 60℃-70℃ to generate a polycationic liquid dispersant.

[0029] The mass ratio of the compound of formula (I) to the initiator is 450-550:1, preferably 480-520:1, and more preferably 500:1; the mass ratio of the compound of formula (I) to the solvent is 1:7.5-9.5, preferably 1:8-9.5, and more preferably 1:9; the solvent includes, but is not limited to, any one or any combination of dimethylformamide (DMF), n-butanol, methanol, ethanol, isopropanol, ethyl acetate, toluene, butyl acetate, and anisole, preferably dimethylformamide; the initiator includes, but is not limited to, any one or any combination of azobisisobutyronitrile (AIBN), azobisisobutyronitrile valerate (ACPA), persulfate, organic peroxide, and hydroperoxide, preferably azobisisobutyronitrile (AIBN).

[0030] The self-polymerization reaction is carried out at 60℃-70℃ for 12-24 hours, with stirring during the reaction at a speed of 400-500 rpm.

[0031] After the self-polymerization reaction is completed, the reaction solution is dripped into a washing solvent to precipitate the precipitate, which is then dried to obtain the polycationic liquid dispersant. The volume ratio of the washing solvent to the reaction solution is 2:1. The washing solvent is selected from any one of cold diethyl ether, ethyl acetate (EA), methyl tert-butyl ether (MTBE), diisopropyl ether (DIPE), a mixture of pentane / hexane, and toluene, preferably cold diethyl ether.

[0032] The mass ratio of the compound of formula (I) to the methacrylate compound is 5-6.5:1, preferably 5.5-6:1, more preferably 5.6-5.7:1; the mass ratio of the solvent to the compound of formula (I) is 9.5-11.5:1, preferably 10-11:1, more preferably 10.5-10.6:1; the mass ratio of the chain transfer agent to the compound of formula (I) is 1:140-143, preferably 1:141-142, more preferably 1:141.5-142, and even more preferably 1:141.6-141.7; the mass ratio of the chain transfer agent to the initiator is 2-4:1, preferably 3:1; the methacrylate compound includes, but is not limited to, methyl methacrylate (MMA), isobornyl methacrylate (IBOMA), and methacrylic acid. Dimethylamine ethyl ester (DMAEMA), preferably methyl methacrylate; the solvent includes, but is not limited to, dimethylformamide (DMF), n-butanol, methanol, ethanol, isopropanol, ethyl acetate, toluene, butyl acetate, anisole, or any combination thereof, preferably dimethylformamide; the chain transfer agent includes, but is not limited to, 2-cyano-2-propyldodecylthionaphthalene ester (CPDN), S-thiobenzoyl mercaptoacetic acid (BTTAA), trithiocarbonate (TTC), or any combination thereof, preferably 2-cyano-2-propyldodecylthionaphthalene ester (CPDN); the initiator includes, but is not limited to, azobisisobutyronitrile (AIBN), azobisisobutyronitrile valerate (ACPA), persulfate, organic peroxide, hydroperoxide, or any combination thereof, preferably azobisisobutyronitrile (AIBN).

[0033] The inert gas includes, but is not limited to, any one or any combination of helium, neon, argon, krypton, xenon, and radon.

[0034] The reversible addition-fragmentation chain transfer polymerization reaction was carried out at 60℃-70℃ for 12-24h, with stirring during the reaction at a speed of 400-500rpm.

[0035] After the reversible addition-fragmentation chain transfer polymerization reaction is completed, the reaction solution is dripped into a washing solvent to precipitate the product. The precipitate is then dried to obtain the polycationic liquid dispersant. The volume ratio of the washing solvent to the reaction solution is 2:1. The washing solvent is selected from any one of cold diethyl ether, ethyl acetate (EA), methyl tert-butyl ether (MTBE), diisopropyl ether (DIPE), a mixture of pentane / hexane, and toluene, preferably cold diethyl ether.

[0036] The preparation of the compound of formula (I) includes: mixing 11-haloundecyl acrylate, imidazole compound and polymerization inhibitor under an inert atmosphere or nitrogen atmosphere, and reacting at 40±2℃ to obtain the compound of formula (I).

[0037] Under the inert atmosphere or nitrogen atmosphere, the gas flow rate is ≥50 mL / min, and the inert gas includes, but is not limited to, any one or any combination of helium, neon, argon, krypton, xenon, and radon.

[0038] The molar ratio of the 11-haloundecyl acrylate to the imidazole compound is 1:1-2, preferably 1:1-1.5, and more preferably 1:1.2; the amount of polymerization inhibitor is 0.01-0.02 wt% of the total mass of the 11-haloundecyl acrylate and the imidazole compound, preferably 0.01 wt%; in the 11-haloundecyl acrylate, the substituted halogen atom is selected from fluorine, chlorine, bromine, and iodine atoms, and more preferably bromine; the imidazole compound is selected from any one of 1-methylimidazolium, 1,2-dimethylimidazolium, and N-butylimidazolium, preferably 1-methylimidazolium; the polymerization inhibitor is selected from any one of butylated hydroxytoluene (BHT) and 4-Hydroxy-TEMPO, preferably butylated hydroxytoluene (BHT).

[0039] Further, the reaction was carried out at 40±2℃ for 24-48 h, with stirring during the reaction at a speed of 200-400 rpm. After the reaction was completed, the mixture was washed three times with diethyl ether, with a volume ratio of diethyl ether to reaction solution of 2:1 each time. Then, it was diluted with dichloromethane to a solid content of 20-30 wt%, evaporated at room temperature for 24 h, and dried under vacuum at 45 ℃ to obtain compound (I). The halogen content in compound (I) is ≤0.5 wt%.

[0040] The preparation of the 11-haloundecyl acrylate includes: adding acryloyl chloride to an organic solvent containing 11-haloundecyl alcohol in a low-temperature environment under the action of an acid-binding agent, and reacting to obtain 11-haloundecyl acrylate.

[0041] In the reaction system, the molar ratio of 11-haloundecaneol to acryloyl chloride is 1:0.9-2, preferably 1:1-1.5, and more preferably 1:1.2; the molar ratio of 11-haloundecaneol to the acid-binding agent is 1:0.9-2, preferably 1:1-1.5, and more preferably 1:1.2; the molar ratio of 11-haloundecaneol to the organic solvent is 0.1-1 mmol:1 mL, preferably 0.3-0.6 mmol:1 mL, and more preferably 0.5 mmol:1 mL. mmol:1mL; the substituted halogen atom in the 11-haloundecanool is selected from fluorine, chlorine, bromine, and iodine atoms, and is more preferably bromine; the acid-binding agent is selected from any one or any combination of triethylamine, pyridine, 4-dimethylaminopyridine, diisopropylethylamine, potassium carbonate, sodium carbonate, potassium hydroxide, and sodium hydroxide, and is preferably triethylamine; the organic solvent is selected from any one or any combination of tetrahydrofuran (THF), dichloromethane (DCM), acetonitrile, N,N-dimethylformamide (DMF), ethyl acetate, and acetone, and is preferably THF.

[0042] Further, acryloyl chloride was added to an organic solvent containing 11-haloundecaneol at 0℃-5℃, and the reaction was carried out at room temperature to obtain 11-haloundecyl acrylate. Even further, acryloyl chloride was added to an organic solvent containing 11-haloundecaneol at 0℃-5℃ for 0.5-1 h, and the reaction was allowed to mature at 25℃ for 24-48 h to obtain 11-haloundecyl acrylate. The reaction was carried out with stirring at a speed of 200-400 rpm.

[0043] Further, after the reaction was completed, the organic phase was filtered and washed and extracted three times with sodium bicarbonate aqueous solution (2%). The upper oil phase was collected, dried with anhydrous sodium sulfate, and the dried oil phase was rotary evaporated to remove THF. Then, column chromatography (petroleum ether: ethyl acetate = 50:1) was performed to purify and obtain 11-haloundecyl acrylate.

[0044] The polycationic liquid dispersant described above in this invention can be used to prepare carbon nanomaterial dispersions.

[0045] The present invention also provides a carbon nanomaterial dispersion containing a cationic monomer for a polycationic liquid dispersant as described above, or a polycationic liquid dispersant as described above, carbon nanomaterials, and a solvent. The mass percentage of the solvent in the polycationic liquid dispersant, carbon nanomaterials, and solvent is 90 wt%-99.5 wt%, preferably 95 wt%-99 wt%, more preferably 97 wt%-98.5 wt%. In one embodiment, the mass percentage of the solvent is 98 wt%. The mass ratio of the cationic monomer for a polycationic liquid dispersant, carbon nanomaterials, and the above-mentioned polycationic liquid dispersant to the carbon nanomaterials is 0.2-5:1, preferably 0.5-3:1, more preferably 0.8-1.5:1. In one embodiment, the mass ratio of the cationic monomer for a polycationic liquid dispersant, carbon nanomaterials, and the above-mentioned polycationic liquid dispersant to the above-mentioned polycationic liquid dispersant is 1:1. The carbon nanomaterials include, but are not limited to, any one or any combination of carbon nanotubes, graphene, and carbon nanofibers, and the carbon nanotubes include, but are not limited to, single-walled carbon nanotubes and / or multi-walled carbon nanotubes. The solvent is water and / or an organic solvent, and the organic solvent is selected from, or any combination of, N-methylpyrrolidone, dimethylformamide, dimethyl sulfoxide, γ-butyrolactone, 1,3-dimethyl-2-imidazolinone, chloroform, dichloromethane, acetone, and isopropanol.

[0046] This invention provides a method for preparing a carbon nanomaterial dispersion, comprising the following steps: adding carbon nanomaterials to water and / or an organic solvent containing a cationic monomer or a polycationic liquid dispersant as described above, and uniformly dispersing under mechanical force to obtain a carbon nanomaterial dispersion. Further, after adding the remaining water and / or organic solvent, uniformly dispersing under mechanical force to obtain a carbon nanomaterial dispersion. The mechanical force includes, but is not limited to, ultrasound, stirring, shearing, and microfluidics. Specifically, ultrasound at 200-1000 W power for 30 min, shearing at 5000 rpm for 10 min, or microfluidic at 50 MPa for 1 pass, results in zero sedimentation of the obtained carbon nanomaterial dispersion after 30 days.

[0047] The carbon nanomaterial dispersion of the present invention can be used to prepare coatings, which have electrical conductivity, and / or thermal conductivity, and / or antistatic properties.

[0048] The polycationic liquid dispersant of the present invention has a polymer number-average molecular weight (Mn) of 30-80 kDa, ionic liquid units ≥80%, and Tg of 120-150℃; it is used to efficiently disperse graphene, single-walled carbon nanotubes and multi-walled carbon nanotubes to form a stable dispersion, which shows no precipitation after standing for more than 7 days, has a viscosity <100 mPa•s, and a volume resistivity ≤10 Ω•cm.

[0049] This invention provides a coating having electrical conductivity, and / or thermal conductivity, and / or antistatic properties, containing the following components by weight percentage: The carbon nanomaterial dispersion of the present invention: 20-22 wt% Film-forming resin: 40-60 wt%, preferably 50-55 wt%, more preferably 50-53 wt%; the film-forming resin is selected from any one of polyurethane resin, acrylic resin or polyester resin, preferably polyurethane resin; The remainder is a solvent, which is selected from any one or any combination of N-methylpyrrolidone, dimethylformamide, ethylene glycol, butyl ether, or water, preferably deionized water.

[0050] The coating also contains a dispersant, which has a mass percentage of 0.3-0.5 wt%. The dispersant is selected from any one or any combination of Disperbyk-190, Disperbyk-192, Disperbyk-194, fatty alcohol polyoxyethylene ether methylsilane, cationic polyacrylamide (CPAM), and polyquaternary ammonium salt (PQ-22), with Disperbyk-190 being preferred.

[0051] The coating also contains a leveling agent, which has a mass percentage of 0.4-0.6 wt%. The leveling agent is selected from any one or any combination of polyether siloxane (BYK-345), non-silicone acrylate (MODAREZ PW / AX), polyester modified silicone (BYK-310), styrene-acrylic octyl acrylate copolymer, and fluorinated leveling agent (MODAREZ X080), preferably BYK-345.

[0052] The coating also contains a defoamer, which has a mass percentage of 0.3-0.6 wt%. The defoamer is selected from any one or any combination of TEGO Airex901W, mineral oil-siloxane composite (HY-420), BYK-066N, polyether modified siloxane, and siloxanes, with TEGO Airex901W being preferred.

[0053] The coating also contains a wetting agent, which is 1.5-1.7 wt% by mass. The wetting agent is selected from any one or any combination of DISPERBYK-2012, octylphenol polyoxyethylene ether (OP-10), DISPERBYK-161, sodium diisooctyl sulfosuccinate (OT-75), and polyvinylpyrrolidone (PVP K30), preferably OT-75.

[0054] The present invention also provides a method for preparing a coating, comprising the steps of: adding the carbon nanomaterial dispersion and solvent described above to a film-forming resin under stirring, and mixing evenly to obtain the coating.

[0055] The carbon nanomaterial dispersion of the present invention has a mass percentage of 20-22 wt%; the film-forming resin has a mass percentage of 40-60 wt%, preferably 50-55 wt%, more preferably 50-53 wt%; the film-forming resin is selected from any one of polyurethane resin, acrylic resin or polyester resin, preferably polyurethane resin; the remainder is solvent, which is selected from any one or any combination of N-methylpyrrolidone, dimethylformamide, ethylene glycol, butyl ether or water, preferably water.

[0056] Furthermore, a dispersant, and / or a leveling agent, and / or an antifoaming agent, and / or a wetting agent are added to the film-forming resin. The dispersant has a mass percentage of 0.3-0.5 wt%, and is selected from any one or any combination of Disperbyk-190, Disperbyk-192, Disperbyk-194, fatty alcohol polyoxyethylene ether methylsilane, cationic polyacrylamide (CPAM), and polyquaternary ammonium salt (PQ-22), preferably Disperbyk-190. The leveling agent has a mass percentage of 0.4-0.6 wt%, and is selected from any one or any combination of polyether siloxane (BYK-345), non-silicone acrylate (MODAREZ PW / AX), polyester modified silicone (BYK-310), styrene-acrylic octyl acrylate copolymer, and fluorinated leveling agent (MODAREZ X080), preferably BYK-345. The defoamer has a mass percentage of 0.3-0.6 wt%, and is selected from any one or any combination of TEGO Airex901W, mineral oil-siloxane composite (HY-420), BYK-066N, polyether-modified siloxane, and siloxanes, preferably TEGO Airex901W. The wetting agent has a mass percentage of 1.5-1.7 wt%. The wetting agent is selected from any one or any combination of DISPERBYK-2012, octylphenol polyoxyethylene ether (OP-10), DISPERBYK-161, sodium diisooctyl sulfosuccinate (OT-75), and polyvinylpyrrolidone (PVPK30), preferably OT-75.

[0057] The coating provided by the present invention forms a continuous three-dimensional ion-conducting network after curing, giving the coating electrical conductivity and / or thermal conductivity and / or antistatic properties. The curing temperature is 25-180℃ and the curing time is 0.5-4h.

[0058] This invention primarily involves the esterification reaction of 11-bromoundecyl alcohol and acryloyl chloride to obtain a flexible spacer acrylate bromide composed of long-chain alkyl groups. The bromine end is then quaternized with 1-methylimidazole to obtain IL-Br, forming a "long-chain imidazole cation." Finally, IL-Br is polymerized with a small amount of conventional methacrylate via reversible addition-fragmentation chain transfer polymerization (RAFT) to obtain the target PIL-co-PMMA, achieving copolymerization with a small amount of comonomers. This realizes a three-in-one molecular design of "long-chain imidazole cation + flexible spacer group + small amount of comonomer copolymerization," solving the pain points of traditional dispersants such as "easy desorption, poor thermal stability, and incompatibility with the matrix." This provides a feasible path for the large-scale application of CNTs in conductive coatings, electromagnetic shielding, flexible electronics, and other fields.

[0059] This invention first synthesizes an imidazolium bromide ionic liquid monomer (IL-Br) using a low-temperature esterification-quaternization process. Then, methacrylates are introduced into the main chain via reversible addition-fragmentation chain transfer polymerization (RAFT) to obtain a polycationic liquid PIL-co-PMMA. Subsequently, PIL-co-PMMA is ultrasonically dispersed with carbon nanomaterials (graphene, single-walled carbon nanotubes, and multi-walled carbon nanotubes) to form a high-solids, low-viscosity dispersion slurry with zero sedimentation after 30 days. This slurry is then crosslinked with a film-forming resin and additives to obtain a coating with excellent electrical conductivity, thermal conductivity, and antistatic properties. The prepared PIL-co-PMMA-carbon nanotube / graphene conductive, thermally conductive, and antistatic coating not only has an extremely low percolation threshold (≤4 wt%) and a surface resistivity of 10... 2 -10 9 Ω / m 2 Adjustable, thermal conductivity ≥1.5 W / m -1 K -1 Furthermore, the conductive network remains stable under both visible light and dark environments, making it widely applicable in functional coatings fields such as flexible electronics, 5G base stations, and lithium battery packaging, demonstrating significant application value. In addition, the preparation method of this invention is economical and practical, with readily available raw materials and abundant sources of imidazole monomers. It is also eco-friendly, requiring no special equipment or stringent conditions, and is easy to scale up for production, thus possessing strong industrial application value. Attached Figure Description

[0060] Figure 1 This is an image of IL-Br prepared in Example 1 of the present invention.

[0061] Figure 2The NMR spectrum of IL-Br prepared in Example 1 of this invention.

[0062] Figure 3 Image of PIL-co-PMMA prepared in Example 3 of this invention.

[0063] Figure 4 Infrared spectra of IL-Br prepared in Example 1, PIL prepared in Example 2, and PIL-co-PMMA prepared in Example 3 of this invention.

[0064] Figure 5 These are comparative images of carbon nanotube dispersions from Examples 1, 2, and 3 of the present invention, Comparative Example 1 (blank control without carbon nanotubes), Comparative Example 2, and Comparative Example 3. Detailed Implementation

[0065] The technical solution of the present invention will be further described in detail and completely below with reference to the embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Experimental methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the manufacturer.

[0066] Example 1 In this embodiment, IL-Br monomer is used to prepare carbon nanomaterial dispersion and is used to formulate coating. The specific preparation process is as follows: Synthesis of IL-Br monomer: In a 500 mL three-necked flask equipped with a constant pressure dropping funnel, thermometer, and magnetic stirrer, 11-bromoundecyl alcohol (25.12 g, 100 mmol), triethylamine (12.14 g, 120 mmol), and anhydrous THF (150 mL) were added, and the mixture was cooled to 0–5 °C. Acryloyl chloride (9.7 mL, 120 mmol) in a THF solution (50 mL) was added dropwise over 30 min, and the mixture was stirred at room temperature for 48 h. The white precipitate was removed by filtration, and the filtrate was washed three times with 2% NaHCO3 aqueous solution. The upper organic phase was collected and dried overnight in anhydrous MgSO4. THF was removed by rotary evaporation, and the mixture was purified by silica gel column chromatography (petroleum ether: ethyl acetate = 50:1) to give 22.1 g of a golden-yellow transparent liquid of 11-bromoundecyl acrylate, with a yield of 87.3%. 11-Bromoundecyl acrylate (50 mmol), 1-methylimidazole (60 mmol), and BHT (0.01 wt%) were mixed and reacted at 40 °C for 48 h under nitrogen protection. After the reaction was completed, the mixture was washed three times with diethyl ether (ether to reaction liquid volume ratio 2:1), diluted with dichloromethane (solid content 20-30 wt%), evaporated at room temperature, and dried under vacuum at 45 °C to obtain 19.8 g of white powder IL-Br (bromine content ≤0.5 wt%), yield 92%, melting point 63-65 °C.

[0067] Preparation of IL-Br carbon nanomaterial dispersion: IL-Br:CNT:H2O were prepared in a jar at a mass ratio of 1:1:98 and sonicated at 1000 W for 30 min to obtain a uniform and stable carbon nanomaterial dispersion.

[0068] Coating preparation and sample preparation: Under a stirring speed of 600 rpm, 21 g of IL-Br-carbon nanomaterial dispersion, 0.5 g of leveling agent BYK-345, 0.5 g of defoamer TEGO Airex 901W, 1.6 g of wetting agent OT-75, 0.4 g of dispersant Disperbyk-190, and 26 g of deionized water were added sequentially to 50 g of polyurethane resin. The mixture was stirred at room temperature for 50 min to ensure uniform mixing of all components, thus obtaining the IL-Br dispersed carbon nanomaterial coating.

[0069] Coating and molding: The slurry is uniformly coated onto the substrate surface using a scraping method, with the wet film thickness controlled at approximately 100 μm. It is then cured in an oven at 50 °C for 2 hours.

[0070] Example 2 Synthesis of PIL copolymer: 10 g of IL-Br, 90 g of DMF, and 0.02 g of AIBN were added to a Schlenk tube. The mixture was subjected to three cycles of liquid nitrogen freezing, vacuuming, and nitrogen purging, and then reacted in an oil bath at 60°C for 20 h. The reaction solution was precipitated by adding cold diethyl ether, centrifuged, filtered, and dried under vacuum at 45°C for 24 h to obtain a pale yellow polymer. This polymer has Mn = 48 kDa, an ionic liquid unit content ≥90%, and Tg = 142 °C.

[0071] Preparation of PIL-carbon nanomaterial dispersion: PIL:CNT:H2O in a mass ratio of 1:1:98 was prepared in a jar and ultrasonicated at 1000 W for 30 min to obtain a uniform and stable carbon nanomaterial dispersion. The dispersion showed no precipitation after standing for 30 days, with a viscosity of 10 mPa·s and a volume resistivity of 6 Ω·cm.

[0072] Coating preparation and sample preparation: Under the condition of stirring speed of 600 rpm, 21 g of PIL-carbon nanomaterial dispersion slurry, 0.5 g of leveling agent BYK-345, 0.5 g of defoamer TEGO Airex 901W, 1.6 g of wetting agent OT-75, 0.4 g of dispersant Disperbyk-190, and 26 g of deionized water were added to 50 g of polyurethane resin in sequence. The mixture was stirred at room temperature for 50 min to ensure that all components were mixed evenly, thus obtaining the PIL-dispersed carbon nanomaterial coating.

[0073] Coating and molding: The slurry is uniformly coated onto the substrate surface using a scraping method, with the wet film thickness controlled at approximately 100 μm. It is then cured in an oven at 50 °C for 2 hours.

[0074] Example 3 Synthesis of PIL-co-PMMA copolymer: 8.5 g of IL-Br, 1.5 g of MMA, 90 g of DMF, 0.06 g of CPDN, ​​and 0.02 g of AIBN were added to a Schlenk tube. The mixture was subjected to three cycles of liquid nitrogen freezing, vacuuming, and nitrogen purging, followed by a 20-h reaction in an oil bath at 60°C. The reaction solution was then precipitated by adding cold diethyl ether, centrifuged, filtered, and dried under vacuum at 45°C for 24 h to obtain a transparent polymer film (PIL-co-PMMA copolymer dispersion). ≤1.3). The copolymer has Mn = 62 kDa, approximately 80% ionic liquid units, and Tg = 128 °C.

[0075] Preparation of PIL-co-PMMA carbon nanomaterial dispersion: PIL-co-PMMA:CNT:H2O in a mass ratio of 1:1:98 was prepared in a container and sonicated at 1000 W for 30 min to obtain a uniform and stable carbon nanomaterial dispersion. The dispersion showed no precipitation after standing for 30 days, with a viscosity of 14 mPa·s and a volume resistivity of 5 Ω·cm, and can be directly used for the preparation of conductive coatings.

[0076] Coating preparation and sample preparation: Under a stirring speed of 600 rpm, 21 g of PIL-co-PMMA carbon nanomaterial dispersion, 0.5 g of leveling agent BYK-345, 0.5 g of defoamer TEGO Airex901W, 1.6 g of wetting agent OT-75, 0.4 g of dispersant Disperbyk-190, and 26 g of deionized water were added sequentially to 50 g of polyurethane resin. The mixture was stirred at room temperature for 50 min to ensure uniform mixing of all components, thus obtaining a coating of PIL-co-PMMA dispersed carbon nanomaterials.

[0077] Coating and molding: The slurry is uniformly coated onto the substrate surface using a scraping method, with the wet film thickness controlled at approximately 100 μm. It is then cured in an oven at 50 °C for 2 hours.

[0078] Comparative Example 1 The difference between this comparative example and the embodiment is that no carbon nanomaterials were added during the preparation of the coating. The specific preparation process is as follows: Coating preparation and sample preparation: Under the condition of stirring speed of 600 rpm, 47 g of deionized water, 0.5 g of leveling agent BYK-345, 0.5 g of defoamer TEGO Airex 901W, 1.6 g of wetting agent OT-75 and 0.4 g of dispersant Disperbyk-190 were added to 50 g of polyurethane resin in sequence. The mixture was stirred at room temperature for 50 min to ensure that the components were mixed evenly, and the blank control group coating was obtained.

[0079] Coating and molding: The slurry is uniformly coated onto the substrate surface using a scraping method, with the wet film thickness controlled at approximately 100 μm. It is then cured in an oven at 50 °C for 2 hours.

[0080] Comparative Example 2 The difference between this comparative example and the embodiment is that carbon nanomaterials not dispersed with surfactants were added during the preparation of the coating. The specific preparation process is as follows: Preparation of carbon nanomaterial dispersion: CNT:H2O was prepared in a jar at a mass ratio of 1:99 and ultrasonicated at 1000 W for 30 min to obtain carbon nanomaterial dispersion.

[0081] Coating preparation and sample preparation: Under the condition of stirring speed of 600 rpm, 21 g of carbon nanomaterial dispersion paste, 0.5 g of leveling agent BYK-345, 0.5 g of defoamer TEGO Airex 901W, 1.6 g of wetting agent OT-75, 0.4 g of dispersant Disperbyk-190, and 26 g of deionized water were added to 50 g of polyurethane resin in sequence. The mixture was stirred at room temperature for 50 min to ensure that all components were mixed evenly, thus obtaining a coating containing carbon nanomaterials.

[0082] Coating and molding: The slurry is uniformly coated onto the substrate surface using a scraping method, with the wet film thickness controlled at approximately 100 μm. It is then cured in an oven at 50 °C for 2 hours.

[0083] Comparative Example 3 The difference between this comparative example and the previous example is that carbon nanomaterials dispersed using traditional small-molecule surfactants were added during the preparation of the coating. The specific preparation process is as follows: Preparation of surfactant-carbon nanomaterial dispersion: The surfactant cetyltrimethylammonium bromide (CTAB):CNT:H2O was prepared in a tank at a mass ratio of 1:1:98 and ultrasonicated at 1000 W for 30 min to obtain a uniform and stable carbon nanomaterial dispersion.

[0084] Coating preparation and sample preparation: Under the condition of stirring speed of 600 rpm, 21 g of surfactant-carbon nanomaterial dispersion slurry, 0.5 g of leveling agent BYK-345, 0.5 g of defoamer TEGO Airex901W, 1.6 g of wetting agent OT-75, 0.4 g of dispersant Disperbyk-190, and 26 g of deionized water were added to 50 g of polyurethane resin in sequence. The mixture was stirred at room temperature for 50 min to ensure that all components were mixed evenly, thus obtaining a surfactant-dispersed carbon nanomaterial coating.

[0085] Coating and molding: The slurry is uniformly coated onto the substrate surface using a scraping method, with the wet film thickness controlled at approximately 100 μm. It is then cured in an oven at 50 °C for 2 hours.

[0086] Table 1 shows the effects of the use and type of dispersant on the dispersibility and stability of carbon nanomaterials; the appearance of the experimentally prepared IL-Br is as follows. Figure 1 As shown; the 1H NMR spectrum of IL-Br is as follows. Figure 2 As shown; the appearance of the experimentally prepared PIL-co-PMMA is as follows. Figure 3 As shown; the infrared spectra of the experimentally prepared IL-Br and PIL-co-PMMA are as follows. Figure 4 As shown; comparative images of carbon nanotube dispersions from Examples 1, 2, 3, Comparative Examples 1, 2, and 3 are shown. Figure 5 As shown.

[0087] Table 1. Effects of dispersant use and type on the dispersibility and stability of carbon nanomaterials. As shown in Table 1, the tests revealed that surface resistivity, thermal conductivity, and sedimentation rate are all related to dispersibility and stability. Better dispersibility and stability result in lower sedimentation rates, smaller surface resistivity, and higher thermal conductivity. Comparisons showed that the dispersion performance and stability were significantly improved under the action of IL-Br, PIL, and PIL-co-PMMA, demonstrating that polyionic liquids and their monomers possess excellent dispersibility and stability properties for carbon nanomaterials.

[0088] Figure 1 The image shows the appearance of IL-Br after preparation and storage. After vacuum drying, it is a white powdery solid that may absorb moisture when exposed to air.

[0089] Figure 2The 1H NMR spectrum of IL-Br confirms its complete synthesis. Observation of the spectrum reveals the presence of the methylene group at 4.18 ppm with an integral of 2H, indicating complete esterification. The 3H terminus of the acrylic acid terminal olefin remains intact, the double bond is not destroyed, and the 2H terminus of the imidazole ring shifts to 10.3 ppm, a typical characteristic of quaternization. A new -N group appears. + CH2- and -N-CH3 indicate that 1-methylimidazole has been alkylated.

[0090] Figure 3 The image shows the appearance of PIL-co-PMMA in its storage state after preparation. After vacuum drying, it is a transparent, slightly yellow film that may absorb moisture when exposed to air.

[0091] Figure 4 Infrared spectra of IL-Br and PIL-co-PMMA. Observation of the spectra reveals that the spectrum of IL-Br is in the range of 1635-1645 cm⁻¹. -1 The C=C stretching vibration peak of acrylic acid can be clearly observed at this point, indicating that the double bond has not been destroyed. The peak value of PIL-co-PMMA decreases significantly at this point, indicating that the polymerization reaction is complete and the target product has been formed. (The peak value is located at 1560-1575 cm⁻¹.) -1 The imidazole ring C=N can still be observed at 3100-3120 cm⁻¹. -1 The presence of the imidazole ring CH indicates that the imidazole ring structure has not been damaged.

[0092] Figure 5 Comparative images of carbon nanotube dispersions from Examples 1, 2, 3, Comparative Examples 1, 2, and 3 show that the dispersion performance and stability of the ionic liquid and polyionic liquid dispersants are superior to the comparative samples.

[0093] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any person skilled in the art may make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A cationic monomer for a polycationic liquid dispersant, characterized in that, As shown in the compound of formula (Ⅰ): Among them, anion R - R1 is selected from any one of fluoride ion, chloride ion, bromide ion, and iodide ion, and R2 is selected from methyl or butyl ion.

2. The method for preparing a cationic monomer for a polycationic liquid dispersant according to claim 1, characterized in that the step... The process involves mixing 11-haloundecyl acrylate, imidazole compounds, and polymerization inhibitors under an inert or nitrogen atmosphere, and reacting at 40±2℃ to obtain compound (Ⅰ).

3. A polycationic liquid dispersant, characterized in that, It is prepared by self-polymerization of the compound of formula (I); or, It is prepared by reversible addition-fragmentation chain transfer polymerization of compound (I) and methacrylate compounds; compound (I) is shown below: Among them, anion R - R1 is selected from any one of fluoride ion, chloride ion, bromide ion, and iodide ion, and R2 is selected from methyl or butyl ion.

4. The method for preparing a polycationic liquid dispersant according to claim 3, characterized in that the step... include: Compound (I), initiator, and solvent are mixed, frozen with liquid nitrogen, evacuated, and purged with inert gas or nitrogen circulation. The mixture self-polymerizes at 60℃-70℃ to form a polycationic liquid dispersant; or... The compound of formula (I) as described in claim 3, methacrylate compounds, chain transfer agents, initiators and solvents are mixed, frozen with liquid nitrogen, vacuumed, and purged with inert gas or nitrogen circulation, and a reversible addition-fragmentation chain transfer polymerization reaction is carried out at 60℃-70℃ to generate a polycationic liquid dispersant.

5. The cationic monomer of the polycationic liquid dispersant according to claim 1 or the polycationic liquid dispersant according to claim 3 is used to prepare a carbon nanomaterial dispersion.

6. A dispersion of carbon nanomaterials, characterized in that, The mixture contains a cationic monomer for a polycationic liquid dispersant as described in claim 1 or a polycationic liquid dispersant as described in claim 3, carbon nanomaterials, and a solvent. The solvent content in the mixture of the cationic monomer for a polycationic liquid dispersant as described in claim 1 or a polycationic liquid dispersant as described in claim 3, carbon nanomaterials, and solvent is 90 wt%-99.5 wt%. The mass ratio of the cationic monomer for a polycationic liquid dispersant as described in claim 1 or a polycationic liquid dispersant as described in claim 3 to the carbon nanomaterials is 0.2-5:

1.

7. The method for preparing a carbon nanomaterial dispersion according to claim 6, characterized in that, step... include: Carbon nanomaterials are added to water and / or an organic solvent containing a cationic monomer for a polycationic liquid dispersant as described in claim 1 or a polycationic liquid dispersant as described in claim 3, and uniformly dispersed under mechanical force to obtain a carbon nanomaterial dispersion.

8. The carbon nanomaterial dispersion of claim 6 is used to prepare a coating, wherein the coating has electrical conductivity, and / or thermal conductivity, and / or antistatic properties.

9. A coating having electrical conductivity, and / or thermal conductivity, and / or antistatic properties, characterized in that, Contains the following components by weight percentage: A carbon nanomaterial dispersion as described in claim 6: 20-22 wt% Film-forming resin: 40-60 wt%.

10. The method for preparing a coating according to claim 9, characterized in that, The steps include: Under stirring, a carbon nanomaterial dispersion as described in claim 6 is added to the film-forming resin and mixed evenly to obtain the final product.

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