Polyacrylate-based hyperdispersant, its preparation and use

Abstract

This invention discloses a method for preparing a polyacrylate-based superdispersant. First, dimethylaminoethyl methacrylate is reacted with an initiator and a RAFT reagent to generate a RAFT macromolecular active chain transfer agent; this macromolecular active chain transfer agent has a number-average molecular weight of 3000-6000 and a molecular weight distribution coefficient (PDI) ≤1.3. Then, the macromolecular active chain transfer agent is reacted with butyl acrylate monomer under the induction of an initiator to generate a PDMAEMA-B-PBA block copolymer, which is the acrylate-based superdispersant. When the acrylate-based superdispersant prepared by this invention is used as a dispersant for nano-ceramic powders, it disperses nano-sized ceramic powders through chain segment anchoring, steric hindrance, and electrostatic repulsion, preventing particle agglomeration and increasing the dispersion stability of particles in solvents.

Description

Technical Field

[0001] This invention belongs to the field of polymer superdispersant preparation technology, specifically relating to a polyacrylate superdispersant for dispersing nano-ceramic powders, its preparation and application. Background Technology

[0002] Nanoceramic powders, with their dense structure and superior mechanical properties, have become a research hotspot in the field of ceramic materials in recent years. However, due to the small particle size, large specific surface area, numerous interfacial atoms, large number of unsaturated and dangling bonds, and high chemical reactivity of nanoparticles, they are prone to forming large agglomerates. Therefore, obtaining uniformly dispersed powders is particularly important for the preparation of nanoscale ceramics.

[0003] Traditional small-molecule and low-molecular-weight dispersants have certain limitations in their molecular structure: hydrophilic groups do not bind firmly to the surfaces of particles with low polarity or nonpolarity, making them prone to desorption and leading to re-flocculation of ions after dispersion; lipophilic groups do not have sufficient carbon chain length (generally no more than 18 carbon atoms), and cannot generate enough steric hindrance to provide stability in non-aqueous dispersion systems. Hyperdispersants overcome the limitations of traditional dispersants in non-aqueous dispersion systems. Their molecular chains also possess hydrophilic and lipophilic properties, and compared to traditional dispersants, they can better disperse and stabilize nanoparticles in the medium. The molecular weight of hyperdispersants is generally between 1000 and 10000, and their molecular structure contains two completely different parts with different properties and functions: the first part is anchoring groups, which can be tightly adsorbed onto the surface of solid particles through ionic bonds, covalent bonds, hydrogen bonds, and van der Waals forces, making it difficult for the hyperdispersant and solid particles to desorb. The second part is the solvated polymer chain. In a polarity-matched dispersion medium, the solvated chain has good compatibility with the dispersion medium and adopts a relatively extended conformation in the dispersion medium. It forms a protective layer of sufficient thickness on the surface of solid particles and provides more steric hindrance to prevent solid particles from getting closer to each other and agglomerating.

[0004] High-molecular-weight acrylate dispersants are widely used due to their ability to effectively and stably disperse organic and inorganic powders through electrostatic repulsion and steric hindrance. Currently, the polymerization of acrylate monomers mainly employs living anionic polymerization, conventional free radical polymerization, group transfer polymerization, and atom transfer radical polymerization (ATRP). Conventional free radical polymerization offers poor control over the relative molecular weight and distribution of the polymer, while group transfer polymerization and anionic polymerization offer high monomer selectivity but require stringent reaction conditions, limiting their application. Although ATRP offers relatively mild polymerization conditions, the metal catalyst needs to be removed after polymerization, resulting in impurities in the inorganic nanoparticles.

[0005] Reversible addition-fragmentation chain transfer (RAFT) polymerization controls the concentration of growing radicals in the polymerization system by reversibly transferring chains from growing radicals to RAFT reagents (dithioester compounds), thereby controlling the polymerization reaction. RAFT polymerization offers advantages such as a wide range of monomer adaptability, mild polymerization conditions, and produces polymers with low dispersion index, high functionality, and a more concentrated molecular weight distribution. It is currently the most promising controlled / living radical polymerization method for industrial application.

[0006] CN102010491A discloses a method for preparing a block copolymer of dimethylaminoethyl methacrylate and butyl acrylate. This method uses a low-concentration divalent copper salt as a catalyst. In the presence of an organic reducing agent, dimethylaminoethyl methacrylate undergoes electron transfer regeneration catalyst atom transfer radical polymerization to synthesize a macromolecular initiator. The macromolecular initiator is then used to initiate the polymerization of butyl acrylate, yielding an amphiphilic block copolymer poly(dimethylaminoethyl methacrylate-b-butyl acrylate). The patent mentions that the synthesized macromolecular initiator has a molecular weight of 15,000 and a molecular weight distribution coefficient (MDC) < 2.0; the amphiphilic block copolymer has a molecular weight of 25,000 and a MDC < 2.0. The molecular weights are high, and the MDC range is wide. However, the high-valent metal halide catalyst used is unstable under certain conditions and is prone to certain side reactions during polymerization. Furthermore, the metal catalyst is difficult to completely remove from the polymer, which may result in residues in the final product.

[0007] CN112592419A discloses a method for preparing an acrylic quaternary ammonium salt film with both contact antibacterial and anti-fogging properties: Dimethylaminoethyl methacrylate (DMAEMA) and butyl acrylate (BA) are added to an ethanol solvent, and free radical polymerization initiated by AIBN is used to obtain a binary copolymer precursor PBD; the precursor copolymer is dissolved in the organic solvent ethanol, and bromobenzoyl (OB) is added for ionization to prepare the quaternary ammonium salt polymer PBD-OB; a certain mass of PBD-OB polymer is weighed and dissolved again in an ethanol solution, and 1-bromo-4-chlorobutane (BrC4H8Cl) is added for crosslinking reaction; the mixture is poured into a mold, and the solvent is allowed to evaporate naturally at room temperature to obtain the acrylic quaternary ammonium salt film with both antibacterial and anti-fogging properties. However, the method does not control the molecular weight and molecular weight distribution coefficient of this polymer film, nor does it mention its application in the field of nano-ceramic powder dispersion. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to provide a polyacrylate superdispersant for dispersing nano-ceramic powders, its preparation and application in the field of nano-ceramic dispersion.

[0009] According to a first objective of the present invention, the present invention provides a polyacrylate-based superdispersant.

[0010] Specifically, the polyacrylate superdispersant is a poly(dimethylaminoethyl methacrylate)-butyl acrylate copolymer with a number-average molecular weight (M). n (The molecular weight is 7000-10000, the molecular weight distribution is narrow, and the molecular weight distribution coefficient (PDI) is 1.1-1.3).

[0011] According to a second objective of the present invention, the present invention provides a method for preparing the above-mentioned polyacrylate hyperdispersant.

[0012] Specifically, the preparation method of the polyacrylate hyperdispersant includes the following steps:

[0013] (1) Add dimethylaminoethyl methacrylate (DMAEMA) monomer, initiator A, RAFT reagent B and solvent C to the reaction vessel, heat the reaction under an inert atmosphere for a period of time and then quench the reaction to terminate the reaction.

[0014] (2) Separate the polymer solution obtained in step (1) to obtain RAFT macromolecular active chain transfer agent (macro-PDMAEMA);

[0015] (3) Add the RAFT macromolecular active chain transfer agent (macro-PDMAEMA) obtained in step (2), butyl acrylate monomer, initiator D and solvent E into the reactor, heat the reaction for a period of time in an inert atmosphere and then quench the reaction to terminate the reaction.

[0016] (4) Separate the polymer solution obtained in step (3) to obtain the polyacrylate superdispersant (i.e., poly(dimethylaminoethyl methacrylate-butyl acrylate)).

[0017] According to the present invention, the initiator A in step (1) is either benzoyl peroxide (BPO) or azobisisobutyronitrile (AIBN).

[0018] According to the present invention, the RAFT reagent B in step (1) is one of 4-cyano-4-[[(dodecylthioalkylthiocarbonyl)thioalkyl]valeric acid, 2-(dodecyltrithiocarbonyl)-2-methylpropionic acid and S-(2-cyano-2-propyl)-S-dodecyltrithiocarbonyl ester.

[0019] According to the present invention, the RAFT reagent B is preferably a trithioester compound. Although trithioester reagents have only one more sulfur atom than common dithioester reagents, they can provide more stable free radicals during polymerization and have higher efficiency in chain transfer, making it easier to precisely control the molecular weight distribution of the polymer.

[0020] According to the present invention, the solvent C in step (1) is one of toluene, ethanol and ethyl acetate.

[0021] According to the present invention, the molar ratio of dimethylaminoethyl methacrylate monomer, RAFT reagent B and initiator A in step (1) is 50-100:1:0.2-0.3.

[0022] According to the present invention, the volume ratio of solvent C to dimethylaminoethyl methacrylate in step (1) is 2:1 to 4:1.

[0023] According to the present invention, the reaction temperature in step (1) is 60-70°C, and the reaction time is 2-6 hours. The reaction in step (1) is preferably carried out under water bath heating conditions.

[0024] According to the present invention, the inert atmosphere described in steps (1) and (3) is selected from nitrogen or other inert gases.

[0025] According to the present invention, the separation described in steps (2) and (4) employs conventional techniques in the art. For example, it may include: removing the solvent using a rotary evaporator, adding the precipitate dropwise to an excess of petroleum ether, filtering, redissolving in tetrahydrofuran solution, repeating this process three times, collecting the precipitate, and drying it in a vacuum drying oven at 40-60°C for 12-18 hours until constant weight.

[0026] According to the present invention, the number-average molecular weight (Mn) of the RAFT macromolecular active chain transfer agent (macro-PDMAEMA) obtained in step (2) is 3000-6000, and the molecular weight distribution coefficient (PDI) is ≤1.3. This macromolecular active chain transfer agent is generated through an addition reaction between a RAFT reagent (containing a trithioester compound structure -S=C(S)-S-) and a growing free radical. It is an intermediate active free radical capable of reversible decomposition. This intermediate active free radical can both decompose to produce reactants and generate temporarily inactivated macromolecular dormant species, which can continue to initiate polymerization reactions, thereby enabling better control of the polymerization reaction.

[0027] According to the present invention, the initiator D in step (3) is either benzoyl peroxide (BPO) or azobisisobutyronitrile (AIBN).

[0028] According to the present invention, the solvent E in step (3) is one of toluene, ethanol and ethyl acetate.

[0029] According to the present invention, in step (3), the molar ratio of butyl acrylate monomer, RAFT macromolecular active chain transfer agent (macro-PDMAEMA), and initiator D is 150-300:1:0.2-0.3.

[0030] According to the present invention, the volume ratio of solvent E to butyl acrylate in step (3) is 2:1 to 4:1.

[0031] According to the present invention, the reaction temperature in step (3) is 50–70°C, and the reaction time is 5–12 h. Preferably, the reaction temperature in step (3) is 5–10°C lower than the reaction temperature in step (1). The reaction in step (3) is preferably carried out under water bath heating conditions.

[0032] According to a third objective of the present invention, the present invention also provides the application of polyacrylate superdispersants in the dispersion of nano-ceramic powders.

[0033] According to the present invention, the specific application includes: dispersing nano-ceramic powder and polyacrylate superdispersant in an organic solvent, mixing thoroughly to obtain a nano-ceramic slurry.

[0034] According to the present invention, the organic solvent is selected from one or more of ethanol, acetone, butanone, n-butanol, ethyl acetate, and toluene.

[0035] According to the present invention, the nano-ceramic powder is selected from one or more of alumina (Al₂O₃), silicon dioxide (SiO₂), titanium dioxide (TiO₂), zirconium oxide (ZrO₂), yttrium oxide (Y₂O₃), and nickel oxide (NiO). The D of the nano-ceramic powder... V (50) Particle size ≤100nm, preferably D V (50) Ceramic powder with a particle size of 50-75nm.

[0036] Furthermore, in the obtained nano-ceramic slurry, the amount of polyacrylate polymer superdispersant added is 0.5wt% to 2wt% of the amount of nano-ceramic powder.

[0037] Furthermore, in the obtained nano-ceramic powder slurry, the amount of nano-ceramic powder is 40wt%-60wt% of the total weight of the slurry.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] 1. In the preparation of the superdispersant of this invention, dimethylaminoethyl methacrylate is first reacted with an initiator and a RAFT reagent to generate a macro-PDMAEMA (a macro-active chain transfer agent). The RAFT chain transfer agent is a trithiocarbonate reagent, which exhibits lower inhibition and higher hydrolytic stability compared to traditional dithiocarbonate reagents. The resulting linear RAFT macro-active chain transfer agent is a temporarily deactivated macromolecular dormant species containing an RS=C(S)-S- group at one end. It can either grow free radicals to react and be further activated, or undergo reversible cleavage to generate new active free radical chains to further initiate polymerization. The number-average molecular weight (Mn) of this macro-active chain transfer agent is 3000-6000, and the molecular weight distribution coefficient (PDI) is ≤1.3. Then, the macro-active chain transfer agent is reacted with butyl acrylate (BA) monomer under the initiator to generate a PDMAEMA-B-PBA block copolymer, which is the acrylate-based polymeric superdispersant.

[0040] 2. Many metal oxides in ceramic powders, such as Al2O3, SiO2, TiO2, and ZrO2, have the ability to attract hydroxyl groups on their surfaces. These oxides typically have active sites on their surfaces that can be used for water molecule adsorption and hydroxyl group attraction. This invention selects dimethylaminoethyl methacrylate containing amino anchoring groups and acrylates with good molecular chain flexibility as monomers. After block copolymerization, the nanoscale ceramic powder is dispersed through the anchoring effect of chain segments, steric hindrance, and electrostatic repulsion. On one hand, this type of acrylate superdispersant can fully contact the ceramic powder in the solvent. The anchoring groups [-N(CH3)] on the polymethylaminoethyl methacrylate molecular chain segments interact with the hydroxyl groups of the ceramic powder to form hydrogen bonds, tightly binding and making the surface of the ceramic powder particles organic. On the other hand, the butyl acrylate in the superdispersant molecule is a solvation segment that extends in the solvent. When the ceramic powder particles approach each other, the solvation segment acts as a steric hindrance, preventing particle agglomeration and increasing the dispersion stability of the particles in the solvent.

[0041] 3. In this invention, a polyacrylate polymer superdispersant with a molecular weight between 7,000 and 10,000 and a narrow molecular weight distribution coefficient (≤1.3) is synthesized by RAFT polymerization. It is applied to disperse single-phase or composite inorganic nano-ceramic powder particles with a particle size of tens of nanometers, such as Al2O3, SiO2, TiO2, Y2O3, ZrO2, and NiO, and has excellent dispersion effect. Attached Figure Description

[0042] Figure 1 This is a schematic diagram illustrating the method for measuring relative settlement height.

[0043] Figure 2 This is a molecular gel permeation chromatography (GPC) chromatogram of the polyacrylic acid-based superdispersant prepared in Example 1. Detailed Implementation

[0044] The technical solution of the present invention will be described in more detail below with reference to specific embodiments. In the examples and comparative examples, all chemical reagents used were commercially available standard chemical reagents. The purity of all chemical reagents was analytical grade (AR). The polymers prepared in the examples and comparative examples were determined and analyzed by gel permeation chromatography (GPC). The analytical instrument used was a Waters 1515 gel permeation chromatograph. The experimental test conditions were: temperature 35℃, mobile phase V(tetrahydrofuran THF):V(triethanolamine TEA) = 50:1, flow rate 1 mL / min, and polystyrene standard was used to correct the chromatography.

[0045] Example 1

[0046] The preparation method of the polyacrylate hyperdispersant includes the following steps:

[0047] (1) 9.42 g (0.06 mol) of dimethylaminoethyl methacrylate (DMAEMA), 0.346 g (1 mmol) of RAFT reagent S-(2-cyano-2-propyl)-S-dodecyl trithiocarbonyl ester, 0.041 g (0.25 mmol) of initiator azobisisobutyronitrile (AIBN), and 30 mL of ethanol solution were added to the reaction vessel. Nitrogen gas was purged into the reactor for 30 min to remove air from the reactor. The reaction was then heated in a water bath at 60 °C for 4 h. Subsequently, the reaction was quenched in an ice-water bath to terminate the reaction.

[0048] (2) The obtained polymer solution was evaporated using a rotary evaporator to remove the ethanol solvent. The precipitate was then added dropwise to an excess of petroleum ether. After filtration, the precipitate was redissolved in tetrahydrofuran solution. This process was repeated three times. The precipitate was collected and dried in a vacuum drying oven at 60°C for 12 hours until constant weight was achieved. The RAFT macromolecular active chain transfer agent (macro-PDMAEMA) was obtained.

[0049] (3) 19.2 g (0.15 mol) butyl acrylate, 4.832 g (0.001 mol) RAFT macromolecular active chain transfer agent (macro-PDMAEMA), 0.041 g (0.25 mmol) azobisisobutyronitrile (AIBN), and 60 mL ethanol were added to the reactor. Nitrogen gas was purged into the reactor for 30 min to remove air. The reactor was then heated in a 50 °C water bath for 6 h. The reaction was then terminated by quenching in an ice-water bath.

[0050] (4) After removing the ethanol solvent using a rotary evaporator, the obtained polymer solution was added dropwise to an excess of petroleum ether to precipitate the polymer. After filtration, the precipitate was redissolved in tetrahydrofuran solution. This process was repeated three times, and the precipitate was collected and dried in a vacuum drying oven at 60°C for 12 hours until constant weight was achieved. The final product, poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) polymeric superdispersant, was obtained.

[0051] Example 2

[0052] The preparation method of the polyacrylate hyperdispersant includes the following steps:

[0053] (1) 7.85 g (0.05 mol) of dimethylaminoethyl methacrylate (DMAEMA), 0.346 g (1 mmol) of RAFT reagent S-(2-cyano-2-propyl)-S-dodecyl trithiocarbonyl ester, 0.0328 g (0.2 mmol) of initiator azobisisobutyronitrile (AIBN), and 30 mL of ethanol solution were added to the reaction vessel. Nitrogen gas was purged into the reactor for 30 min to remove air from the reactor. The reaction was then heated in a water bath at 60 °C for 3 h. Subsequently, the reaction was quenched in an ice-water bath to terminate the reaction.

[0054] (2) The obtained polymer solution was evaporated using a rotary evaporator to remove the ethanol solvent. The precipitate was then added dropwise to an excess of petroleum ether. After filtration, the precipitate was redissolved in tetrahydrofuran solution. This process was repeated three times. The precipitate was collected and dried in a vacuum drying oven at 50°C for 12 hours until constant weight was achieved. The RAFT macromolecular active chain transfer agent (macro-PDMAEMA) was obtained.

[0055] (3) 25.6 g (0.2 mol) butyl acrylate, 5.729 g (0.001 mol) RAFT macromolecular active chain transfer agent (macro-PDMAEMA), 0.041 g (0.25 mmol) azobisisobutyronitrile (AIBN), and 77 mL ethanol were added to the reactor. Nitrogen gas was purged into the reactor for 30 min to remove air. The reactor was then heated in a water bath at 55 °C for 5 h. The reaction was then terminated by quenching in an ice-water bath.

[0056] (4) After removing the ethanol solvent using a rotary evaporator, the obtained polymer solution was added dropwise to an excess of petroleum ether to precipitate the polymer. After filtration, the precipitate was redissolved in tetrahydrofuran solution. This process was repeated three times. The precipitate was collected and dried in a vacuum drying oven at 50°C for 12 hours until constant weight was achieved. The final product, poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) polymeric superdispersant, was obtained.

[0057] Example 3

[0058] The preparation method of the polyacrylate hyperdispersant includes the following steps:

[0059] (1) 9.42 g (0.06 mol) of dimethylaminoethyl methacrylate (DMAEMA), 0.404 g (0.001 mol) of RAFT reagent 4-cyano-4-[[(dodecylthiocarbonylthio)thioalkyl]valeric acid, 0.041 g (0.25 mmol) of initiator azobisisobutyronitrile (AIBN), and 30 mL of toluene solution were added to the reaction vessel. Nitrogen gas was purged into the reactor for 30 min to remove air from the reactor, and then the reaction was heated in a 60 °C water bath for 5 h. Subsequently, the reaction was quenched in an ice-water bath to terminate the reaction.

[0060] (2) The obtained polymer solution was evaporated using a rotary evaporator to remove the ethanol solvent. The precipitate was then added dropwise to an excess of petroleum ether. After filtration, the precipitate was redissolved in tetrahydrofuran solution. This process was repeated three times. The precipitate was collected and dried in a vacuum drying oven at 60°C for 12 hours until constant weight was achieved. The RAFT macromolecular active chain transfer agent (macro-PDMAEMA) was obtained.

[0061] (3) 19.2 g (0.15 mol) butyl acrylate, 5.362 g (0.001 mol) RAFT macromolecular active chain transfer agent (macro-PDMAEMA), 0.0328 g (0.2 mmol) azobisisobutyronitrile (AIBN), and 60 mL toluene were added to the reactor. Nitrogen gas was purged into the reactor for 30 min to remove air. The reactor was then heated in a 50 °C water bath for 6 h. The reaction was then terminated by quenching in an ice-water bath.

[0062] (4) After removing the ethanol solvent using a rotary evaporator, the obtained polymer solution was added dropwise to an excess of petroleum ether to precipitate the polymer. After filtration, the precipitate was redissolved in tetrahydrofuran solution. This process was repeated three times, and the precipitate was collected and dried in a vacuum drying oven at 60°C for 12 hours until constant weight was achieved. The final product, poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) polymeric superdispersant, was obtained.

[0063] Example 4

[0064] The preparation method of the polyacrylate hyperdispersant includes the following steps:

[0065] (1) 12.56 g (0.08 mol) of dimethylaminoethyl methacrylate (DMAEMA), 0.365 g (0.001 mol) of RAFT reagent 2-(dodecyltrithiocarbonate)-2-methylpropionic acid, 0.073 g (0.3 mmol) of initiator benzoyl peroxide (BPO), and 40 mL of toluene solution were added to the reaction vessel. Nitrogen gas was purged into the reactor for 30 min to remove air from the reactor, and then the reaction was heated in a 70 °C water bath for 2 h. Subsequently, the reaction was quenched in an ice-water bath to terminate the reaction.

[0066] (2) The obtained polymer solution was evaporated using a rotary evaporator to remove the ethanol solvent. The precipitate was then added dropwise to an excess of petroleum ether. After filtration, the precipitate was redissolved in tetrahydrofuran solution. This process was repeated three times. The precipitate was collected and dried in a vacuum drying oven at 50°C for 18 hours until constant weight was achieved. The RAFT macromolecular active chain transfer agent (macro-PDMAEMA) was obtained.

[0067] (3) 38.4 g (0.3 mol) butyl acrylate, 3.634 g (0.001 mol) RAFT macromolecular chain active transfer agent (macro-PDMAEMA), 0.073 g (0.3 mmol) benzoyl peroxide (BPO) and 128 mL toluene were added to the reactor. Nitrogen gas was purged into the reactor for 30 min to remove air. The reactor was then heated in a 65 °C water bath for 3 h. The reaction was then quenched in an ice-water bath to terminate the reaction.

[0068] (4) After removing the ethanol solvent using a rotary evaporator, the obtained polymer solution was added dropwise to an excess of petroleum ether to precipitate the polymer. After filtration, the precipitate was redissolved in tetrahydrofuran solution. This process was repeated three times, and the precipitate was collected and dried in a vacuum drying oven at 50°C for 18 hours until constant weight was achieved. The final product, poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) polymeric superdispersant, was obtained.

[0069] Comparative Example 1

[0070] A different method than that used in this invention—atomic transfer radical polymerization (ATRP)—was employed to prepare a poly(dimethylaminoethyl methacrylate)-butyl acrylate polymer, which was then used as a dispersant to disperse nano-ceramic powders, and the dispersion effect was compared.

[0071] In this process, ethyl 2-bromoisobutyrate was selected as the initiator, cuprous bromide as the catalyst, 2,2-bipyridine as the ligand, and isopropanol as the solvent. The molar ratio was methyl methacrylate: ethyl 2-bromoisobutyrate: cuprous bromide: 2,2-bipyridine = 35:1:1:2. The product was obtained by reacting under vacuum at 45°C for a period of time. The product was then purified and separated to obtain poly(dimethylaminoethyl methacrylate) macromolecular chain transfer agent.

[0072] The macromolecular chain transfer agent was then used as a new initiator to undergo secondary polymerization with butyl acrylate monomer, catalyst, and ligand. After reacting at 60°C for a period of time, the mixture was purified and dried to obtain poly(dimethylaminoethyl methacrylate)-butyl acrylate polymer. The molar ratio of butyl acrylate, macromolecular chain transfer agent, catalyst, and ligand was 100:1:0.5:1.

[0073] Comparative Example 2

[0074] The preparation process is basically the same as in Example 1. The difference is that this comparative example uses a dithiocarbonate RAFT reagent: 4-cyano-4-(thiobenzoyl)valerate. The first polymerization yields the RAFT macromolecular chain transfer agent, and the second polymerization yields the poly(dimethylaminoethyl methacrylate)-butyl acrylate polymer.

[0075] Comparative Example 3

[0076] The preparation process is basically the same as that in Example 1. The difference is that step (1) of this comparative example uses a conventional chain transfer agent - dodecyl mercaptan; the first polymerization first obtains a macromolecular chain, and the second polymerization obtains a poly(dimethylaminoethyl methacrylate)-butyl acrylate polymer.

[0077] Example 5

[0078] Select commercially available nano-ceramic powder: a certain proportion of Y2O3 doped with ZrO2 (D v (50) Particles with a diameter ≤300 nm were mixed with the poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) superdispersant prepared in Example 1, ethanol, and methyl ethyl ketone (MEK) as a binary solvent. The mixture was then added to a graduated cylinder and allowed to stand. The mass fraction of the superdispersant was 0.5% of the nano-ceramic powder. The mass fraction of the nano-ceramic powder was 50% of the dispersion. The dispersion stability (RSH value) of the dispersion was observed at regular intervals. The results are listed in Table 2.

[0079] Example 6

[0080] Select commercially available nano-ceramic powder: a certain proportion of Y2O3 doped with ZrO2 (D v (50) Particles with a diameter ≤300 nm were mixed with the poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) superdispersant prepared in Example 2, ethanol, and methyl ethyl ketone (MEK) as a binary solvent. The mixture was then added to a graduated cylinder and allowed to stand. The mass fraction of the superdispersant was 0.5% of the nano-ceramic powder. The mass fraction of the nano-ceramic powder was 50% of the dispersion. The dispersion stability (RSH value) of the dispersion was observed at regular intervals. The results are listed in Table 2.

[0081] Example 7

[0082] Select commercially available nano-ceramic powder: a certain proportion of Y2O3 doped with ZrO2 (D v(50) Particles with a diameter ≤300 nm were mixed with the poly(dimethylaminoethyl methacrylate-butyl acrylate) (PDMAEMA-B-PBA) superdispersant prepared in Example 3 and ethanol solvent, and then added to a graduated cylinder and allowed to stand. The mass fraction of the superdispersant was 0.5% of the nano-ceramic powder. The mass fraction of the nano-ceramic powder was 50% of the dispersion. The dispersion stability (RSH value) of the dispersion was observed at regular intervals. The results are listed in Table 2.

[0083] Example 8

[0084] Select commercially available nano-ceramic powder: a certain proportion of Y2O3 doped with ZrO2 (D v (50) Particles with a diameter ≤300 nm were mixed with the poly(dimethylaminoethyl methacrylate-butyl acrylate) (PDMAEMA-B-PBA) superdispersant prepared in Example 4 and ethanol solvent, and then added to a graduated cylinder and allowed to stand. The mass fraction of the superdispersant was 0.5% of the nano-ceramic powder. The mass fraction of the nano-ceramic powder was 50% of the dispersion. The dispersion stability (RSH value) of the dispersion was observed at regular intervals. The results are listed in Table 2.

[0085] Comparative Example 4

[0086] Select commercially available nano-ceramic powder: a certain proportion of Y2O3 doped with ZrO2 (D v (50) Particles with a diameter ≤300 nm were mixed with the poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) superdispersant prepared in Comparative Example 1, ethanol, and methyl ethyl ketone (MEK) as a binary solvent. The mixture was then added to a graduated cylinder and allowed to stand. The mass fraction of the superdispersant was 0.5% of the nano-ceramic powder. The mass fraction of the nano-ceramic powder was 50% of the dispersion. The dispersion stability (RSH value) of the dispersion was observed at regular intervals. The results are listed in Table 2.

[0087] Comparative Example 5

[0088] Select commercially available nano-ceramic powder: a certain proportion of Y2O3 doped with ZrO2 (D v (50) Particles with a diameter ≤300 nm were mixed with the poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) superdispersant prepared in Comparative Example 2, ethanol, and methyl ethyl ketone (MEK) as a binary solvent. The mixture was then added to a graduated cylinder and allowed to stand. The mass fraction of the superdispersant was 0.5% of the nano-ceramic powder. The mass fraction of the nano-ceramic powder was 50% of the dispersion. The dispersion stability (RSH value) of the dispersion was observed at regular intervals. The results are listed in Table 2.

[0089] Comparative Example 6

[0090] Select commercially available nano-ceramic powder: a certain proportion of Y2O3 doped with ZrO2 (D v (50) Particles with a diameter ≤300 nm were mixed with the poly(dimethylaminoethyl methacrylate)-butyl acrylate (PDMAEMA-B-PBA) superdispersant prepared in Comparative Example 3, ethanol, and butanone binary solvent. The mixture was then added to a graduated cylinder and allowed to stand. The mass fraction of the superdispersant was 0.5% of the nano-ceramic powder. The mass fraction of the nano-ceramic powder was 50% of the dispersion. The dispersion stability (RSH value) of the dispersion was observed at regular intervals. The results are listed in Table 2.

[0091] Comparative Example 7

[0092] Select commercially available nano-ceramic powder: a certain proportion of Y2O3 doped with ZrO2 (D v (50) Particles ≤300nm) were mixed evenly with the small molecule dispersant polyethylene glycol (PEG), ethanol, and methyl ethyl ketone (MEK) as a binary solvent, and then added to a graduated cylinder and allowed to stand. The mass fraction of the superdispersant was 0.5% of the nano-ceramic powder. The mass fraction of the nano-ceramic powder was 50% of the dispersion. The dispersion stability (RSH value) of the dispersion was observed at regular intervals. The results are listed in Table 2.

[0093] It should be noted that the dispersion effect of the dispersant was observed and analyzed using the sedimentation method, as follows: Figure 1 As shown in the figure. H0 represents the total liquid level, and H represents the sedimentation height. The relative sedimentation height (RSH), which is the ratio of the sedimentation height to the total liquid level, characterizes the dispersion stability of the dispersion. A higher RSH value indicates better dispersion stability and a stronger dispersing effect of the dispersant.

[0094] Table 1 lists the number-average molecular weight and molecular weight distribution coefficient of the macromolecular chain transfer agent obtained by polymerization in step (1) and the poly(dimethylaminoethyl methacrylate)-butyl acrylate polymer obtained by polymerization in step (2) of Examples 1-4 and Comparative Examples 1-3.

[0095] Figure 2 This indicates the gel permeation chromatography (GPC) analysis of the RAFT macromolecular active chain transfer agent (macro-PDMAEMA) in step (1) and the poly(dimethylaminoethyl methacrylate-butyl acrylate) (PDMAEMA-B-PBA) superdispersant in step (2) of Example 1. The results show that the number-average molecular weight (M) of the RAFT macromolecular active chain transfer agent (macro-PDMAEMA) is... n =4953, Molecular weight distribution coefficient (PDI) = 1.21; Number average molecular weight (M) of poly(dimethylaminoethyl methacrylate-butyl acrylate) (PDMAEMA-B-PBA) superdispersant n =8140, molecular weight distribution coefficient (PDI) =1.23.

[0096] Table 1

[0097]

[0098] Table 2. Dispersion results of different dispersants on nano-ceramic powders

[0099]

Claims

1. A polyacrylate-based superdispersant, characterized in that, The polyacrylate superdispersant is a poly(dimethylaminoethyl methacrylate)-butyl acrylate copolymer with a number-average molecular weight of 7,000 to 10,000 and a molecular weight distribution coefficient of 1.1 to 1.

3.

2. The method for preparing the polyacrylate hyperdispersant according to claim 1, characterized in that, Includes the following steps: (1) Add dimethylaminoethyl methacrylate monomer, initiator A, RAFT reagent B and solvent C to the reaction vessel, purge with an inert atmosphere and react for a period of time, then quench the reaction to terminate the reaction. (2) Separate the polymer solution obtained in step (1) to obtain RAFT macromolecular active chain transfer agent; (3) Add the RAFT macromolecular active chain transfer agent, butyl acrylate monomer, initiator D and solvent E obtained in step (2) into the reactor, react for a period of time in an inert atmosphere and then quench the reaction to terminate the reaction. (4) Separate the polymer solution obtained in step (3) to obtain the polyacrylate superdispersant.

3. The preparation method according to claim 2, characterized in that, Initiator A mentioned in steps (1) and (3) is either benzoyl peroxide or azobisisobutyronitrile.

4. The preparation method according to claim 2, characterized in that, The RAFT reagent B mentioned in step (1) is one of 4-cyano-4-[[(dodecylthioalkylthiocarbonyl)thioalkyl]valeric acid, 2-(dodecyltrithiocarbonyl)-2-methylpropionic acid and S-(2-cyano-2-propyl)-S-dodecyltrithiocarbonyl ester, preferably a trithioester compound.

5. The preparation method according to claim 2, characterized in that, The solvents C and E are selected from toluene, ethanol and ethyl acetate.

6. The preparation method according to claim 2, characterized in that, The molar ratio of dimethylaminoethyl methacrylate monomer, RAFT reagent B, and initiator A in step (1) is 50~100:1:0.2~0.

3.

7. The preparation method according to claim 2, characterized in that, In step (1), the volume ratio of solvent C to dimethylaminoethyl methacrylate is 2:1 to 4:1; and / or In step (3), the volume ratio of solvent E to butyl acrylate is 2:1 to 4:

1.

8. The preparation method according to claim 2, characterized in that, The reaction temperature in step (1) is 50~70℃ and the reaction time is 2~6h.

9. The preparation method according to claim 2, characterized in that, The separation described in steps (2) and (4) refers to: after removing the solvent using a rotary evaporator, adding it dropwise to an excess of petroleum ether to precipitate the precipitate, filtering it, redissolving it with tetrahydrofuran solution, repeating this process three times, collecting the precipitate and drying it in a vacuum drying oven at 40-60℃ for 12-18 hours until constant weight.

10. The preparation method according to claim 2, characterized in that, The number-average molecular weight of the RAFT macromolecular active chain transfer agent obtained in step (2) is 3000~6000, and the molecular weight distribution coefficient is ≤1.

3.

11. The preparation method according to claim 2, characterized in that, In step (3), the molar ratio of butyl acrylate monomer, RAFT macromolecular active chain transfer agent, and initiator D is 150~300:1:0.2~0.

3.

12. The preparation method according to claim 2 or 8, characterized in that, The reaction temperature in step (3) is 50~70°C, and the reaction time is 5~12 hours; and / or, The reaction temperature in step (3) is 5-10 °C lower than the reaction temperature in step (1).

13. The application of the polyacrylate superdispersant of claim 1 in the dispersion of nano-ceramic powder.

14. The application according to claim 13, characterized in that, The application includes dispersing nano-ceramic powder and acrylate-based superdispersants in an organic solvent, mixing them thoroughly to obtain a nano-ceramic powder slurry.

15. The application according to claim 2, characterized in that, The organic solvent is selected from one or more of ethanol, acetone, butanone, n-butanol, ethyl acetate, and toluene.

16. The application according to claim 2, characterized in that, The nano-ceramic powder is selected from one or more of alumina, silicon dioxide, titanium dioxide, zirconium oxide, yttrium oxide, and nickel oxide; the D of the nano-ceramic powder V (50) Particle size ≤ 100nm.

17. The application according to claim 2, characterized in that, In the obtained slurry, the amount of polyacrylate superdispersant added is 0.5wt%~2wt% of the amount of nano-ceramic powder; and / or, The amount of nano-ceramic powder added is 40wt%-60wt% of the total weight of the resulting slurry.

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