Dispersion method of nano material in non-polar solvent and stripping and dispersion method of two-dimensional material

Abstract

The invention relates to the technical field of nanometer material dispersion, in particular to a method for dispersing a nanometer material in a non-polar solvent and a method for stripping and dispersing a two-dimensional material. The method for dispersing the nano material in the non-polar solvent comprises the following steps: mixing the nano material, a modifier and the non-polar solvent, and then carrying out ultrasonic treatment, the modifier is a copolymer of an unsaturated amide monomer and methacrylate; the molar ratio of the unsaturated amide monomer to the methacrylate is 1: (3-15); the unsaturated amide monomer is prepared from one or more of maleamic acid, 3-acrylamido benzoic acid, N-acryloyl (trihydroxymethyl) aminomethane and 3-methacryloyl dopamine. According to the method, stable dispersion of the nano material in the non-polar solvent and efficient stripping and stable dispersion of the two-dimensional material can be realized, and the method has universality for different types of nano materials and non-polar solvents.

Description

A method for dispersing nanomaterials in nonpolar solvents, and a method for exfoliating and dispersing two-dimensional materials. Technical Field

[0001] This invention relates to the field of nanomaterial dispersion technology, and in particular to a method for dispersing nanomaterials in nonpolar solvents and a method for exfoliating and dispersing two-dimensional materials. Background Technology

[0002] Nanomaterials, due to their size effect, surface effect, and unique quantum behavior, exhibit excellent mechanical, thermal conductivity, lubrication, and optoelectronic properties, and are widely used in many key fields such as lubricant additives, thermally conductive fluids, organic optoelectronic devices, inks, and coatings. Among them, two-dimensional materials, represented by graphene, boron nitride, molybdenum disulfide, and tungsten disulfide, as well as zero-dimensional and one-dimensional structural materials such as metal oxides, carbon nanotubes, and metal nanoparticles, all demonstrate significant technological potential. Achieving efficient, stable, and structurally intact dispersion of these nanomaterials in liquid media is a prerequisite for their functional utilization and industrial application.

[0003] Currently, the liquid-phase dispersion of nanomaterials and the liquid-phase exfoliation of two-dimensional materials mainly rely on highly polar, high-boiling-point organic solvent systems, typically including N-methylpyrrolidone and N,N-dimethylformamide. These polar solvents, due to their high surface tension and polar intermolecular forces, help weaken interlayer van der Waals forces, thereby promoting material exfoliation and initial dispersion. However, these solvents have significant drawbacks, such as high toxicity, low volatility, poor environmental friendliness, and their high boiling point can easily lead to solvent residues in subsequent processing or devices, affecting system performance. Furthermore, these polar systems exhibit severe compatibility barriers with non-polar environments such as lubricating oils and heat transfer fluids, limiting the widespread application of dispersions in non-polar scenarios.

[0004] In contrast, nonpolar solvents such as paraffin oil, n-hexane, n-octane, and isoalkanes are ideal base media in industries such as lubrication, heat dissipation, and organic electronics due to their low toxicity, rapid evaporation, environmental friendliness, and ease of processing. However, the stable dispersion of nanomaterials in nonpolar systems still faces many challenges. Nonpolar solvents have extremely low dielectric constants, making it impossible to form stable charged layer structures between particles. The lack of electrostatic repulsion forces leads to van der Waals forces dominating the interaction between nanoparticles, making them prone to aggregation and sedimentation. Furthermore, two-dimensional materials often cannot be effectively exfoliated in such media, and it is difficult to obtain structures that can be dispersed for a long time.

[0005] Therefore, how to achieve efficient exfoliation and stable dispersion of nanomaterials, especially two-dimensional materials, in non-polar solvents remains a core technical challenge. Summary of the Invention

[0006] In view of this, the purpose of this invention is to provide a method for dispersing nanomaterials in nonpolar solvents and a method for exfoliating and dispersing two-dimensional materials. This invention enables stable dispersion of nanomaterials in nonpolar solvents, as well as efficient exfoliation and stable dispersion of two-dimensional materials, and is universally applicable to different types of nanomaterials and nonpolar solvents.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: The present invention provides a method for dispersing nanomaterials in a non-polar solvent, comprising the following steps: mixing nanomaterials, a modifier, and a non-polar solvent, followed by ultrasonic treatment; wherein the modifier is a copolymer of an unsaturated amide monomer and methacrylate; wherein the molar ratio of the unsaturated amide monomer to methacrylate is 1:(3~15); wherein the unsaturated amide monomer includes one or more of maleic acid, 3-acrylamidobenzoic acid, N-acryloyl(tris(hydroxymethyl))aminomethane, and 3-methacryloyldopamine.

[0008] Preferably, the structural formula of the methacrylate is CH2=C(CH3)COO-R1, wherein R1 has 4 to 40 carbon atoms.

[0009] Preferably, the methacrylate includes one or more of n-butyl methacrylate, octadecyl methacrylate, hexyl methacrylate, and lauryl methacrylate.

[0010] Preferably, the mass ratio of the nanomaterial to the modifier is (1~5):(1~10).

[0011] Preferably, the total mass of the nanomaterial and the modifier is 0.5 to 10% of the mass of the nonpolar solvent.

[0012] Preferably, the nonpolar solvent includes alkanes, petroleum ethers, toluene, dimethylsiloxane, mineral oils, or polyalphaolefin oils; the alkanes have 5 to 14 carbon atoms.

[0013] Preferably, the ultrasonic treatment further includes: performing a first centrifugation on the ultrasonically treated system to obtain a supernatant; the rotation speed of the first centrifugation is 500~3000 r / min; performing a second centrifugation on the supernatant to discard the upper liquid and obtain the modified nanomaterial; the rotation speed of the second centrifugation is 10000~15000 r / min; and redispersing the modified nanomaterial in a nonpolar solvent.

[0014] Preferably, the ultrasound is a water bath ultrasound, and the temperature of the water bath ultrasound is 0~45℃.

[0015] This invention provides a method for exfoliating and dispersing two-dimensional materials, comprising the following steps: mixing the two-dimensional material, a modifier, and a non-polar solvent, followed by ultrasonic treatment; the thickness of the two-dimensional material is on the micrometer scale; the modifier is a copolymer of an unsaturated amide monomer and methacrylate; the molar ratio of the unsaturated amide monomer to methacrylate is 1:(3~10); the unsaturated amide monomer includes one or more of maleic acid, 3-acrylamidobenzoic acid, N-acryloyl(tris(hydroxymethyl))aminomethane, and 3-methacryloyldopamine.

[0016] Preferably, the ultrasonic treatment further includes: performing a first centrifugation on the ultrasonically treated system to obtain a supernatant; the rotation speed of the first centrifugation is 500~3000 r / min; performing a second centrifugation on the supernatant to discard the upper liquid and obtain the exfoliated two-dimensional material; the rotation speed of the second centrifugation is 10000~15000 r / min; and redispersing the exfoliated two-dimensional material in a non-polar solvent.

[0017] This invention provides a method for dispersing nanomaterials in nonpolar solvents, comprising the following steps: mixing nanomaterials, a modifier, and a nonpolar solvent, followed by ultrasonic treatment; the modifier is a copolymer of an unsaturated amide monomer and methacrylate; the molar ratio of the unsaturated amide monomer to methacrylate is 1:(3~15); the unsaturated amide monomer includes one or more of maleic acid, 3-acrylamidobenzoic acid, N-acryloyl(tris(hydroxymethyl))aminomethane, and 3-methacryloyldopamine. The modifier used in this invention can interact with nanomaterials through non-covalent or covalent bonds, thereby anchoring the nanoparticles (due to the structure of the unsaturated amide monomer). The remaining portion of the modifier surrounds the nanoparticles, preventing nanoparticle aggregation through steric hindrance. Furthermore, the modifier has good nonpolar solvent solubility, allowing for uniform dispersion in the nonpolar solvent, thus ensuring stable dispersion of the nanomaterials in the nonpolar solvent.

[0018] This invention also provides a method for the exfoliation and dispersion of two-dimensional materials. Under ultrasonic action, cavitation bubbles and shear forces cause instantaneous separation between the layers of the two-dimensional material. At this time, the anchoring groups in the modifier are rapidly adsorbed on the newly exposed surface of the sheets, reducing the interfacial energy and preventing recombination, while their long chain segments form a swollen brush layer in the solvent, providing an effective steric hindrance effect, thereby achieving stable dispersion of the exfoliated sheets.

[0019] The method of this invention has good versatility and is applicable to various types of nanoparticles and almost all common two-dimensional materials, all of which can achieve stable dispersion in non-polar solvent systems. The obtained nanomaterials not only possess good dispersibility but also exhibit excellent thermal conductivity and friction-reducing and wear-resistant properties. Attached Figure Description

[0020] Figure 1 shows the thermogravimetric curves of TiO2, PMA-MD, and PMA-MD-TiO2; Figure 2 shows the TEM images of PMA-MD-TiO2 at different magnifications; Figure 3 shows the XRD patterns of pure TiO2 and PMA-MD-TiO2; Figure 4 shows the comparison of the dispersion effects of PMA-MD-TiO2 and TiO2; Figure 5 shows the friction coefficient of PMA-MD-TiO2 and PAO2 as a function of time; Figure 6 shows the dispersion image of PMA-PhCOOH modified nanoparticles after standing for 2 weeks. From left to right, the nanoparticles are fullerene, single-walled carbon nanotubes, graphite, copper nanoparticles, diamond nanoparticles, molybdenum disulfide, iron(III) oxide nanoparticles, and titanium dioxide nanoparticles. Figure 7 shows the dispersion photograph of PMA-OH modified nanoparticles after standing for 2 weeks. From left to right, the nanoparticles are fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C. Figure 8 shows the dispersion photograph of PMA-PDO modified nanoparticles after standing for 2 weeks. From left to right, the nanoparticles are fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, and MOF-CuBTC. Figure 9 shows the dispersion photograph of ODMA-modified nanoparticles after standing for 2 hours. From left to right, the nanoparticles are fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C. Figure 10 shows the dispersion photograph of unmodified nanoparticles after standing for 2 hours. From left to right, the nanoparticles are fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C. Figure 11 shows the dispersion photograph of PMA-PhCOO. The dispersion photographs of H-modified nanoparticles after standing for 2 weeks are shown in the first row followed by the second row, from left to right. The nanoparticles are fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-iron oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C, respectively. Figure 12 shows the dispersion photographs of acrylamide-modified nanoparticles after standing for 2 hours. The nanoparticles are fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-iron oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C, respectively, in the first row followed by the second row, from left to right.Figure 13 shows the dispersion photographs of PMA-PDO modified nanoparticles after only 5 minutes of sonication and 2 hours of standing. From left to right, the nanoparticles are fullerene, single-walled carbon nanotubes, graphite, copper nanoparticles, diamond nanoparticles, molybdenum disulfide, nano-iron oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C. Figure 14 shows the dispersion photographs of PMA-MD-B modified nanoparticles after 2 hours of standing. From left to right, the nanoparticles are fullerene, single-walled carbon nanotubes, graphite, copper nanoparticles, diamond nanoparticles, molybdenum disulfide, nano-iron oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C. Figure 15 shows the solubility photographs of the polymer in n-octane in Comparative Example 7. Figure 16 shows the dispersion photographs of LBA modified nanoparticles after 1 month of standing. In the order of the first row followed by the second row from left to right, the nanoparticles are fullerene, graphite, and... Single-walled carbon nanotubes, nanodiamonds, nanocopper, boron nitride, Ti₂C, nanoferric oxide, nanotitanium dioxide, MOF-CuBTC, nanosilica, molybdenum disulfide; Figure 17 shows the dispersion photographs of PMA-BF modified nanoparticles after standing for 1 month. Arranged from left to right (first row then second row), the nanoparticles are MOF-CuBTC, nanoferric oxide, nanotitanium dioxide, boron nitride, graphite, single-walled carbon nanotubes, fullerene, molybdenum disulfide, nanocopper, nanodiamonds, nanosilica, and Ti₂C; Figure 18 shows the dispersion photographs of PMA-NOH modified nanoparticles after standing for 1 month. Arranged from left to right (first row then second row), the nanoparticles are boron nitride, nanotitanium dioxide, single-walled carbon nanotubes, molybdenum disulfide, nanocopper, MOF-CuBTC, graphite, nanodiamonds, fullerene, Ti₂C, nanosilica, and nanoferric oxide. Detailed Implementation

[0021] This invention provides a method for dispersing nanomaterials in a nonpolar solvent, comprising the following steps: mixing nanomaterials, a modifier and a nonpolar solvent and then subjecting the mixture to ultrasonic treatment.

[0022] Unless otherwise specified, all raw materials used in this invention are commercially available products well known in the art.

[0023] The modifier will be explained below.

[0024] In this invention, the modifier is a copolymer of an unsaturated amide monomer and methacrylate; the molar ratio of the unsaturated amide monomer to methacrylate is 1:(3~15), and in the examples, it can be 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, or 1:15. In this invention, the molar ratio of the unsaturated amide monomer to methacrylate affects the properties of the modifier, and thus the dispersion of the nanomaterials. By controlling the molar ratio of the unsaturated amide monomer to methacrylate within the above range, this invention provides a modifier that is universally applicable to different types of nanomaterials and non-polar solvents.

[0025] In this invention, the unsaturated amide monomer includes one or more of maleamic acid, 3-acrylamidobenzoic acid, N-acryloyl(trismethylol)aminomethane, and 3-methacryloyldopamine; the methacrylate has the structural formula CH2=C(CH3)COO-R1, wherein R1 preferably has 4 to 40 carbon atoms, more preferably 4 to 30, and even more preferably 4 to 20. As a more preferred embodiment, the methacrylate preferably includes one or more of n-butyl methacrylate, octadecyl methacrylate, hexyl methacrylate, and lauryl methacrylate. In embodiments of this invention, the modifier is specifically obtained by copolymerizing maleamic acid and n-butyl methacrylate, 3-acrylamidobenzoic acid and octadecyl methacrylate, N-acryloyl(trismethylol)aminomethane and hexyl methacrylate, or by copolymerizing 3-methacryloyldopamine and lauryl methacrylate.

[0026] In this invention, the preparation method of the modifier preferably includes the following steps: mixing unsaturated amide monomers, methacrylates, initiators and polar organic solvents to carry out a copolymerization reaction to obtain the modifier.

[0027] In this invention, the initiator is preferably azobisisobutyronitrile, tert-butyl hydroperoxide, or benzoyl peroxide; the molar amount of the initiator is preferably 0.15-3% of the total molar amount of the monomer, and in specific embodiments it can be 0.15%, 0.3%, 0.5%, 1%, 1.5%, 2%, 2.5%, or 3%.

[0028] In this invention, the polar organic solvent preferably includes N,N-dimethylformamide, acetonitrile, or tetrahydrofuran. This invention does not impose special requirements on the amount of the polar organic solvent used, as long as it ensures the smooth progress of the copolymerization reaction; this is a conventional approach in the art. In the embodiments of this invention, the mass ratio of the monomer and initiator to the polar organic solvent is 1:2.

[0029] In this invention, the temperature of the copolymerization reaction is preferably 65~100℃, and in specific embodiments it can be 65, 70, 80, 90 or 100℃; the time of the copolymerization reaction is preferably 2~48h, and in specific embodiments it can be 2, 10, 20, 24, 30, 36, 40 or 48h.

[0030] In this invention, the copolymerization reaction is preferably carried out under oil bath conditions. Preferably, the copolymerization reaction is carried out under a protective atmosphere. In an embodiment of this invention, specifically, the reaction system is deoxygenated under nitrogen for half an hour.

[0031] After the copolymerization reaction is completed, the present invention preferably adds methanol to the reaction system to precipitate and separate the polymer, dissolves the obtained polymer with N,N-dimethylformamide and then precipitates and separates it again to purify the polymer and obtain the modifier.

[0032] After obtaining the modifier, the present invention mixes the nanomaterial, the modifier and a non-polar solvent and then performs ultrasonic treatment.

[0033] In this invention, the nanomaterial can be a zero-dimensional nanomaterial, a one-dimensional nanomaterial, or a two-dimensional nanomaterial. The particle size of the nanomaterial is preferably 1-200 nm. Chemically, the nanomaterial can be metal nanoparticles, metal oxides, non-metal oxides, carbon materials, or metal-organic frameworks. Specifically, the metal nanoparticles can be copper, silver, or gold; the metal oxides can be iron(III) oxide, titanium dioxide, copper oxide, zinc oxide, aluminum oxide, or cerium dioxide; the non-metal oxides can be silicon dioxide; the carbon materials can be fullerenes, diamond, or single-walled carbon nanotubes; and the metal-organic frameworks can be CuBTC, UIO-66, or UIO-67. The nanomaterials can be unmodified or surface-modified, and this invention does not impose any particular limitation.

[0034] In this invention, the mass ratio of the nanomaterial to the modifier is preferably (1~5):(1~10), more preferably (1~5):1, and in the embodiments of this invention, it can specifically be 1:1, 2:1, 3:1, 4:1 or 5:1.

[0035] In this invention, the nonpolar solvent preferably includes alkanes, petroleum ethers, toluene, dimethylsiloxane, mineral oil, or polyalphaolefin oil; the alkane preferably has 5 to 14 carbon atoms. Specifically, the alkane can be linear, branched, or cyclic; linear alkanes can specifically be n-pentane, n-hexane, n-octane, or n-dodecane; branched alkanes can specifically be octane or neopentane; cyclic alkanes can specifically be cyclopentane, cyclohexane, or cyclooctane. Specifically, the polyalphaolefin oil can be PAO2, PAO4, or PAO10.

[0036] In this invention, the total mass of the nanomaterial and the modifier is preferably 0.5-10% of the mass of the nonpolar solvent. In the embodiments of this invention, it can be 0.5%, 2%, 3%, 5%, 6.6%, 7.5%, 8%, 9% or 10%.

[0037] In this invention, the ultrasonic treatment is preferably water bath ultrasonic treatment, and the temperature of the water bath ultrasonic treatment is preferably 0~45℃, which can be 5, 10, 15, 20, 25, 30, 35, 40 or 45℃ in specific embodiments. In this invention, the ultrasonic treatment time is preferably 5~120 min, which can be 5, 20, 40, 60, 80, 100 or 120 min in specific embodiments. In this invention, the ultrasonic treatment power is preferably 100~300W, which can be 100, 150, 200, 250 or 300W in specific embodiments; the ultrasonic treatment frequency is preferably 40Hz.

[0038] In this invention, the dispersion of nanomaterials is obtained after ultrasonic treatment. This invention can further process the ultrasonically treated system to improve the purity of the nanomaterial dispersion.

[0039] Specifically, after the ultrasonic treatment, the present invention preferably further includes: performing a first centrifugation on the ultrasonically treated system to obtain a supernatant; the rotation speed of the first centrifugation is 500~3000 r / min; performing a second centrifugation on the supernatant to discard the upper liquid and obtain the modified nanomaterial; the rotation speed of the second centrifugation is 10000~15000 r / min; and redispersing the modified nanomaterial in a nonpolar solvent.

[0040] In this invention, the preferred centrifugation time is 5-20 minutes. This invention removes large, non-dispersible nanomaterials through the first centrifugation process.

[0041] In this invention, the second centrifugation time is preferably 20-40 minutes. This invention removes free modifiers that are not bound to the nanomaterials through the second centrifugation.

[0042] This invention does not have special requirements for the redispersing of the modified nanomaterials in a non-polar solvent; the modified nanomaterials can be directly added to the non-polar solvent and ultrasonicated or stirred until homogeneous. Specifically, ultrasonication for 10-30 minutes is acceptable.

[0043] This invention utilizes the strong polar groups in the modifier to anchor nanoparticles through non-covalent or covalent interactions with nanomaterials. The remaining part of the modifier surrounds the nanoparticles, which can prevent nanoparticle aggregation through steric hindrance. Furthermore, the modifier has good non-polar solvent solubility and can be uniformly dispersed in non-polar solvents, thereby enabling the nanomaterials to be stably dispersed in non-polar solvents.

[0044] This invention provides a method for peeling and dispersing two-dimensional materials, comprising the following steps: mixing two-dimensional materials, a modifier and a non-polar solvent and then subjecting the mixture to ultrasonic treatment; wherein the thickness of the two-dimensional material is on the micrometer scale.

[0045] In this invention, the thickness of the two-dimensional material is in the micrometer range, preferably 0.05~5μm.

[0046] In this invention, the two-dimensional material preferably includes graphite, boron nitride, Bi2Te3, MX2, transition metal carbonitride MXene, or two-dimensional covalent organic framework (COF); in MX2, M is Mo, W, Nb, Ta, Re, or Ti, and X is S, Se, or Te; the transition metal carbonitride MXene can specifically be TiC or VC; the COF can specifically be a two-dimensional layered COF (GCF) prepared from chlorohydrin and melamine.

[0047] In this invention, the method for peeling and dispersing the two-dimensional material differs from the method for dispersing nanomaterials in non-polar solvents in that the nanomaterials are replaced with two-dimensional materials; otherwise, they are the same.

[0048] Specifically, the preferred mass ratio of the two-dimensional material to the modifier is (1-5):1, and in the embodiments of the present invention, it can be 1:1, 2:1, 3:1, 4:1, or 5:1. The total mass of the two-dimensional material and the modifier is preferably 0.5-10% of the mass of the non-polar solvent, and in the embodiments of the present invention, it can be 0.5%, 2%, 3%, 5%, 6.6%, 7.5%, 8%, 9%, or 10%. The ultrasonic treatment is preferably water bath ultrasonic treatment, and the preferred temperature of the water bath ultrasonic treatment is 0-45℃, and in specific embodiments, it can be 5, 10, 15, 20, 25, 30, 35, 40, or 45℃. In the present invention, the preferred ultrasonic treatment time is 5-120 min, and in the embodiments of the present invention, it can be 5, 20, 40, 60, 80, 100, or 120 min. In the present invention, the preferred power of the ultrasonic treatment is 100-300W, and in specific embodiments, it can be 100, 150, 200, 250, or 300W; the preferred frequency of the ultrasonic treatment is 40Hz.

[0049] Preferably, the ultrasonic treatment process further includes: performing a first centrifugation on the ultrasonically treated system to obtain a supernatant; the first centrifugation speed is 500~3000 r / min; performing a second centrifugation on the supernatant to discard the upper liquid and obtain the exfoliated two-dimensional material; the second centrifugation speed is 10000~15000 r / min; and redispersing the exfoliated two-dimensional material in a non-polar solvent.

[0050] The following detailed description, in conjunction with embodiments, illustrates the dispersion method of nanomaterials in nonpolar solvents and the exfoliation and dispersion method of two-dimensional materials provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention.

[0051] Example 1: Preparation of the Modifier: Maleic acid and n-butyl methacrylate in a molar ratio of 1:4, azobisisobutyronitrile (0.15% of total monomer molar amount), and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction was completed, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated and separated again to purify the polymer. The obtained polymer was the target modifier, denoted as PMA-MD.

[0052] Preparation of nanoparticle dispersion: Titanium dioxide (0.5g) and PMA-MD (0.25g) in a mass ratio of 2:1 and 10g of n-hexane were added to a glass bottle. The mixture was ultrasonicated in a water bath at 25℃, 200W, and 40Hz for 15 minutes. After ultrasonication, the mixture was centrifuged at 1000r / min for 10 minutes to remove larger, undispersible nanoparticles. After centrifugation, 15mL of the supernatant was accurately measured using a pipette. The supernatant was then centrifuged at 12000r / min for 30 minutes (to remove unbonded free polymers). After removing the supernatant, the mixture was dried and the solid mass was accurately weighed to be 486mg, denoted as PMA-MD-TiO2.

[0053] Weigh out 200 mg of the above PMA-MD-TiO2 and redisperse it in 10 mL of n-hexane to obtain a stable dispersion of nano-titanium dioxide.

[0054] Structural characterization and performance testing of Example 1: Thermogravimetric analysis was performed on TiO2, PMA-MD and PMA-MD-TiO2. The results are shown in Figure 1. From Figure 1, it can be determined that in PMA-MD-TiO2, titanium dioxide accounts for 25% of the total mass and polymer PMA-MD accounts for 75% of the total mass.

[0055] The morphology of PMA-MD-TiO2 was characterized using a JEM-1200EX transmission electron microscope (TEM). TEM images at different magnifications are shown in Figure 2. Figure 2 shows that the titanium dioxide nanoparticles are relatively uniformly distributed and do not aggregate. This indicates that the dispersant can effectively prevent titanium dioxide aggregation.

[0056] The crystal structures of pure TiO2 and PMA-MD-TiO2 before and after ultrasound were characterized using an XPert PRO PMD X-ray diffractometer (XRD), and the results are shown in Figure 3. As can be seen from Figure 3, the diffraction peak positions of the polymer-modified titanium dioxide did not change significantly, indicating that its crystal structure was not destroyed.

[0057] TiO2 and PMA-MD-TiO2 were added to n-octane and PAO2 at a concentration of 0.1 wt% and allowed to stand. The results are shown in Figure 4. In Figure 4, (a) is a photograph of TiO2 (left) and PMA-MD-TiO2 (right) dispersed for 1 min, and (b) is a photograph of TiO2 (left) and PMA-MD-TiO2 (right) dispersed for 2 weeks. As can be seen from Figure 4, the dispersion stability of TiO2 in nonpolar solvents is significantly improved after modification with PMA-MD.

[0058] Tribological performance testing: TiO2 was tested using the Optimol SRV-IV fretting and wear testing machine (Germany). 2-PMA-MD was added to PAO2 at a concentration of 2 wt% of PAO2. Friction performance was tested under the following conditions: temperature 150℃, frequency 25 Hz, amplitude 1 mm, load 200 N, and time 30 min. The steel balls used in the experiment were 10 mm diameter GCr15 bearing steel, and the lower sample block was a 24 mm diameter GCr15 steel block with a height of 7.9 ± 0.1 mm. The friction coefficient curve is shown in Figure 5. As can be seen from Figure 5, TiO2... 2- The addition of PMA-MD can effectively reduce the friction coefficient of PAO2 base oil. Example 2: Preparation of the modifier: 3-acrylamidobenzoic acid and octadecyl methacrylate (molar ratio 1:9), 0.15% azobisisobutyronitrile (total monomer molar amount), and an appropriate amount of anhydrous N,N-dimethylformamide (mass ratio of materials to solvent 1:2) were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated and separated again to purify the polymer. The obtained polymer is the modifier, denoted as PMA-PhCOOH.

[0059] Preparation of nanomaterial dispersions: 0.5g of fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C were placed in glass vials containing 0.5g of PMA-PhCOOH, and 15mL of n-octane (10.5g) was added to each vial. The vials were then sonicated in a water bath sonicator for 2 hours at a power of 200W and a frequency of 40Hz, with the water bath temperature controlled to prevent it from exceeding 50℃. After sonication, the liquid in the vials was centrifuged at 1000r / min for 10 minutes. After centrifugation, the upper two-thirds of the liquid was collected and centrifuged again at 10000r / min for 30 minutes. The supernatant was removed, and the modified nanomaterials at the bottom were dried.

[0060] The modified nanomaterials were added to n-octane to prepare a nanomaterial dispersion with a concentration of 5 mg / mL. Figure 6 shows photographs of the nanoparticles after two weeks of dispersion. The photographs show that no obvious stratification occurred in the solutions, indicating that the method has good dispersion effect and universality.

[0061] Example 3: Preparation of the Modifier: N-acryloyl(tris(hydroxymethyl))aminomethane and hexyl methacrylate (molar ratio 1:9), azobisisobutyronitrile (total monomer molar amount 0.15%), and an appropriate amount of anhydrous N,N-dimethylformamide (mass ratio of materials to solvent 1:2) were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction was completed, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated and separated again to purify the polymer. The resulting polymer was the modifier, denoted as PMA-OH.

[0062] Preparation of nanomaterial dispersions: 0.5g of fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C were placed in glass vials containing 0.5g of PMA-OH, and 15mL of n-octane (10.5g) was added to each vial. The vials were then sonicated in a water bath sonicator for 2 hours at a power of 200W and a frequency of 40Hz, with the water bath temperature controlled to prevent it from exceeding 50℃. After sonication, the liquid in the vials was centrifuged at 1000r / min for 10 minutes. The upper two-thirds of the liquid was then centrifuged again at 10000r / min for 30 minutes. The supernatant was removed, and the modified nanomaterials at the bottom were dried.

[0063] The modified nanomaterials were added to n-octane to prepare a nanomaterial dispersion with a concentration of 5 mg / mL. Figure 7 shows a photograph of the nanoparticles after two weeks of dispersion. The photograph shows that no obvious stratification occurred in the solution, indicating that the method has good dispersion effect and universality.

[0064] Example 4: Preparation of the modifier: 3-methacrylamide and lauryl methacrylate (molar ratio 1:4), 0.15% azobisisobutyronitrile (total monomer molar amount), and an appropriate amount of anhydrous N,N-dimethylformamide (mass ratio of materials to solvent 1:2) were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction was completed, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated and separated again to purify the polymer. The obtained polymer was designated as PMA-PDO.

[0065] Preparation of nanomaterial dispersions: 0.1 g of fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C were placed in glass vials containing 0.1 g of PMA-PDO. 10 mL of n-octane (7 g) was added to each vial. The vials were then sonicated in a water bath for 2 hours at a power of 200 W and a frequency of 40 Hz. The water bath temperature was controlled to prevent it from exceeding 50°C. After sonication, the liquid in the vials was centrifuged at 1000 r / min for 10 min. After centrifugation, the upper two-thirds of the liquid was centrifuged again at 10000 r / min for 30 min. The supernatant was removed, and the modified nanomaterials at the bottom were dried.

[0066] The modified nanomaterials were added to n-octane to prepare a nanomaterial dispersion with a concentration of 5 mg / mL. Figure 8 shows photographs of the nanoparticles after two weeks of dispersion. The photographs show that no obvious stratification occurred in the solutions, indicating that the method has good dispersion effect and universality.

[0067] Preparation of the nano-dispersion in Comparative Example 1: 0.1 g of octadecyl methacrylate (ODMA) monomer was added to glass vials containing 0.01 g of fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-iron oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C, respectively. 2 mL of n-octane was then added to each vial. The mixture was ultrasonicated in a water bath for 1 hour at a power of 200 W and a frequency of 40 Hz, while controlling the water bath temperature to prevent it from exceeding 50 °C. The dispersion photograph after ultrasonication is shown in Figure 9. Figure 9 shows that the nanoparticles modified with octadecyl methacrylate could not achieve stable dispersion in n-hexane.

[0068] Comparative Example 2: 0.1 g each of the following nanoparticles (without dispersant): fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti₂C, were added to 3 g of n-octane and sonicated for 30 minutes at a power of 200 W and a frequency of 40 Hz. The mixtures were then allowed to stand for 2 hours. The results are shown in Figure 10. Figure 10 shows that all nanoparticles sank to the bottom of the vial.

[0069] In Comparative Example 3, fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-iron oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C (0.1 g) were added to 3 g of n-octane containing 0.04 g of 3-acrylamidobenzoic acid monomer, respectively. After sonication for 30 minutes at a power of 200 W and a frequency of 40 Hz, the mixtures were allowed to stand for 2 hours. The results are shown in Figure 11. Figure 11 shows that all nanoparticles sank to the bottom of the vial.

[0070] The results of Comparative Example 2 show that the unmodified nanomaterials have poor dispersibility in nonpolar solvents. The results of Comparative Examples 1 and 3 show that neither a single unsaturated amide monomer nor a single methacrylate monomer can improve the dispersibility of nanomaterials in nonpolar solvents.

[0071] Comparative Example 4: N-hydroxyethyl acrylamide and octadecyl methacrylate (molar ratio 1:4), 0.15% azobisisobutyronitrile (total monomer molar amount), and an appropriate amount of anhydrous N,N-dimethylformamide (mass ratio of materials to solvent 1:2) were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction was complete, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated again to purify the polymer. The resulting polymer was designated PMA-PNOH.

[0072] Preparation of nanomaterial dispersions: 0.1 g of fullerene, single-walled carbon nanotubes, graphite, nano-copper, nano-diamond, molybdenum disulfide, nano-ferric oxide, nano-titanium dioxide, nano-silica, boron nitride, MOF-CuBTC, and Ti2C were placed in glass vials containing 0.04 g of PMA-PNOH, and 3 g of n-octane was added to each vial. The vials were then ultrasonicated in a water bath for 2 hours at a power of 200 W and a frequency of 40 Hz, with the water bath temperature controlled to prevent it from exceeding 50°C. After ultrasonication, the vials were allowed to stand. Figure 12 shows a dispersion photograph of the acrylamide-modified nanoparticles after standing for 2 hours. The photograph shows that the nanoparticles cannot be stably dispersed in this dispersant. The results of Comparative Example 4 indicate that not all copolymers of unsaturated amide monomers and methacrylates can stably disperse nanomaterials in non-polar solvents.

[0073] The only difference between Comparative Example 5 and Example 4 is the sonication time, which is 2 minutes. Figure 13 shows a dispersion photograph of PMA-PDO modified nanoparticles after only 5 minutes of sonication and 2 hours of standing. The photograph shows that the nanoparticles cannot be stably dispersed in the dispersant. This indicates that too short an ultrasonic dispersion time will lead to poor modification effect, thus affecting the dispersion effect of the nanoparticles.

[0074] The only difference between Comparative Example 6 and Example 1 is that the molar ratio of maleic acid and n-butyl methacrylate was 1:20 when preparing PMA-MD. The resulting polymer was the target modifier, denoted as PMA-MD-B. The dispersion method was the same as in Example 1.

[0075] Figure 14 shows a dispersion photograph of PMA-MD-B modified nanoparticles after standing for 2 hours. The photograph shows that the nanoparticles cannot be stably dispersed in this dispersant.

[0076] Preparation of the modifier in Comparative Example 7 (the only difference from Example 1 is the molar ratio of maleamic acid and n-butyl methacrylate): Maleamic acid and n-butyl methacrylate in a molar ratio of 1:1, azobisisobutyronitrile (0.15% of the total monomer molar amount), and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction was completed, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated and separated again to purify the polymer. The obtained polymer is the target modifier, denoted as PMA-M.

[0077] The polymer was weighed and dispersed in n-octane, as shown in Figure 15. The polymer is insoluble in n-octane and therefore cannot disperse nanoparticles.

[0078] Comparative Examples 6 and 7 show that when the molar ratio of unsaturated amide monomers to methacrylates is not appropriate, the modification effect of nanomaterials will be poor, which in turn affects their dispersion in nonpolar solvents.

[0079] Comparative Example 8: 4-vinylbenzoic acid and lauryl methacrylate (isooctyl methacrylate) in a molar ratio of 1:4, azobisisobutyronitrile (0.15% of total monomer molar amount), and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction was complete, methanol was added to the system to precipitate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated again to purify the polymer. The resulting polymer was designated LBA.

[0080] Preparation of nanomaterial dispersions: 0.1 g of fullerene, graphite, single-walled carbon nanotubes, nanodiamond, nanocopper, boron nitride, Ti₂C, nano-iron oxide, nano-titanium dioxide, MOF-CuBTC, nano-silica, and molybdenum disulfide were placed in glass vials containing 0.04 g of LBA, and 3 g of n-octane was added to each vial. The vials were then ultrasonicated in a water bath for 2 hours at a power of 200 W and a frequency of 40 Hz, with the water bath temperature controlled to prevent it from exceeding 50°C. After ultrasonication, the vials were allowed to stand. Figure 16 shows a dispersion photograph of the LBA-modified nanoparticles after one month of standing. The photograph shows that the polymer can stably disperse some nanoparticles, but its dispersion is not universal.

[0081] Comparative Example 9: Pentafluorophenyl acrylate and lauryl methacrylate (isooctyl methacrylate) in a molar ratio of 1:4, azobisisobutyronitrile (0.15% of total monomer molar amount), and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction was completed, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated again to purify the polymer. The resulting polymer was designated PMA-BF.

[0082] Preparation of nanomaterial dispersions: 0.1 g of MOF-CuBTC, nano-iron oxide, nano-titanium dioxide, boron nitride, graphite, single-walled carbon nanotubes, fullerene, molybdenum disulfide, nano-copper, nano-diamond, nano-silica, and Ti2C were placed in glass vials containing 0.04 g of PMA-BF, and 3 g of n-octane was added to each vial. The vials were then ultrasonicated in a water bath for 2 hours at a power of 200 W and a frequency of 40 Hz, with the water bath temperature controlled to prevent it from exceeding 50°C. After ultrasonication, the vials were allowed to stand. Figure 17 shows a dispersion photograph of the PMA-BF-modified nanoparticles after one month of standing. The photograph shows that the polymer can stably disperse some nanoparticles, but its dispersion is not universal.

[0083] Comparative Example 10: 4-hydroxynaphthalene-1-methacrylate and lauryl methacrylate (isooctyl methacrylate) in a molar ratio of 1:4, 0.15% azobisisobutyronitrile (AIBN) of total monomer molar amount, and an appropriate amount of anhydrous N,N-dimethylformamide were placed in a round-bottom flask. After deoxygenating the reaction system under nitrogen for half an hour, it was heated to 80°C in an oil bath and reacted for 48 hours. After the reaction was completed, methanol was added to the system to precipitate and separate the polymer. The obtained polymer was dissolved in a small amount of N,N-dimethylformamide and then precipitated again to purify the polymer. The resulting polymer was designated PMA-NOH.

[0084] Preparation of nanomaterial dispersions: 0.1 g of boron nitride, nano-titanium dioxide, single-walled carbon nanotubes, molybdenum disulfide, nano-copper, MOF-CuBTC, graphite, nano-diamond, fullerene, Ti2C, nano-silica, and nano-ferric oxide were placed in glass vials containing 0.04 g of PMA-NOH, and 3 g of n-octane was added to each vial. The vials were then ultrasonicated in a water bath for 2 hours at a power of 200 W and a frequency of 40 Hz, with the water bath temperature controlled to prevent it from exceeding 50°C. After ultrasonication, the vials were allowed to stand. Figure 18 shows a dispersion photograph of the PMA-NOH-modified nanoparticles after one month of standing. The photograph shows that the polymer can stably disperse some nanoparticles, but its dispersion is not universal.

[0085] As shown in Comparative Examples 8-10, the type of monomer directly affects the properties of the modifier, and thus the dispersion of nanoparticles. This invention, by selecting specific copolymers of unsaturated amide monomers and methacrylates as modifiers, achieves stable dispersion of nanomaterials in non-polar solvents, and is universally applicable to different types of nanomaterials and non-polar solvents.

[0086] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for dispersing nanomaterials in a nonpolar solvent, characterized in that, Includes the following steps: The nanomaterials, modifier, and non-polar solvent are mixed and then subjected to ultrasonic treatment; the modifier is a copolymer of unsaturated amide monomers and methacrylate; the molar ratio of the unsaturated amide monomers to methacrylate is 1:(3~15); the unsaturated amide monomers include one or more of maleic acid, 3-acrylamidobenzoic acid, N-acryloyl(tris(hydroxymethyl))aminomethane, and 3-methacryloyldopamine.

2. The dispersion method according to claim 1, characterized in that, The structural formula of the methacrylate is CH2=C(CH3)COO-R1, wherein R1 has 4 to 40 carbon atoms.

3. The dispersion method according to claim 2, characterized in that, The methacrylates include one or more of n-butyl methacrylate, octadecyl methacrylate, hexyl methacrylate, and lauryl methacrylate.

4. The dispersion method according to claim 1, characterized in that, The mass ratio of the nanomaterial to the modifier is (1~5):(1~10).

5. The dispersion method according to claim 1 or 4, characterized in that, The total mass of the nanomaterials and modifiers is 0.5 to 10% of the mass of the nonpolar solvent.

6. The dispersion method according to claim 1, characterized in that, The nonpolar solvent includes alkanes, petroleum ethers, toluene, dimethylsiloxane, mineral oils, or polyalphaolefin oils; the alkanes have 5 to 14 carbon atoms.

7. The dispersion method according to claim 1, characterized in that, The ultrasonic treatment further includes: performing a first centrifugation on the ultrasonically treated system to obtain a supernatant; the rotation speed of the first centrifugation is 500~3000 r / min; performing a second centrifugation on the supernatant to discard the upper liquid and obtain the modified nanomaterial; the rotation speed of the second centrifugation is 10000~15000 r / min; and redispersing the modified nanomaterial in a nonpolar solvent.

8. The modification method according to claim 1, characterized in that, The ultrasound is a water bath ultrasound, and the temperature of the water bath ultrasound is 0~45℃.

9. A method for peeling and dispersing two-dimensional materials, characterized in that, The method includes the following steps: mixing a two-dimensional material, a modifier, and a non-polar solvent, followed by ultrasonic treatment; the thickness of the two-dimensional material is in the micrometer range; the modifier is a copolymer of an unsaturated amide monomer and methacrylate; the molar ratio of the unsaturated amide monomer to methacrylate is 1:(3~10); the unsaturated amide monomer includes one or more of maleic acid, 3-acrylamidobenzoic acid, N-acryloyl(tris(hydroxymethyl))aminomethane, and 3-methacryloyldopamine.

10. The peeling and dispersing method according to claim 9, characterized in that, The ultrasonic treatment further includes: performing a first centrifugation on the ultrasonically treated system to obtain a supernatant; the rotation speed of the first centrifugation is 500~3000 r / min; performing a second centrifugation on the supernatant to discard the upper liquid and obtain the exfoliated two-dimensional material; the rotation speed of the second centrifugation is 10000~15000 r / min; and redispersing the exfoliated two-dimensional material in a non-polar solvent.

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