Block copolymer coated silicon dioxide material and preparation method thereof
By forming a block copolymer film on the surface of silica nanoparticles, the problem of easy aggregation of silica nanoparticles in additives is solved, and its uniform addition and performance improvement in organic or inorganic media is achieved.
Patent Information
- Application Number
- CN202510202359.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-24
- Publication Date
- 2025-05-30
AI Technical Summary
Silica nanoparticles tend to aggregate when used as additives, affecting their uniform addition effect in organic or inorganic media.
By reversible addition-break chain transfer (RAFT) polymerization method, a macromolecular chain transfer agent with a specific degree of polymerization is prepared, and silica is modified with a silane coupling agent containing carbon-carbon double bonds. Finally, a block copolymer is formed on the surface of the silica to form a film to form a block copolymer-silica nanocomposite with a core-shell structure.
The uniform coating of silica nanoparticles is achieved to form a colloidal emulsion with good hydrophilicity and dispersion, which solves the problem of silica particles aggregation and improves its performance in the matrix.
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Figure CN120059210A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of nanocomposite materials, and particularly relates to a block copolymer-coated silica material and a preparation method thereof. Background Art
[0002] Silica nanoparticles prepared by the sol-gel method have attracted extensive attention in the field of composite nanomaterials due to their simple preparation method, mild reaction conditions, good particle size uniformity, and easy adjustment of particle size. However, when silica is added as an additive to organic or inorganic media, the addition effect is often affected by the aggregation of silica particles. Therefore, how to regulate the surface properties of silica so that it can be used as a uniform additive to improve the performance of organic or inorganic matrices is the main problem in the research of silica particles.
[0003] Since the silica nanoparticles synthesized by this method are rich in hydroxyl groups on their surfaces, they can be modified with silane coupling agents or reacted with other molecules that can react with hydroxyl groups. For example, silane coupling agents with amino groups can increase the hydrophilicity and dispersibility of silica; silica modified with fluorosilane can obtain high hydrophobicity; silica introduced with a silane coupling agent containing a carbon-carbon double bond can continue to react with monomers to graft polymers. Secondly, the hydroxyl groups on the silica surface can also react with carboxyl groups, so polymers or small molecules containing carboxyl groups can be easily grafted onto the silica surface through reaction, thereby achieving the purpose of modifying silica. In recent years, the research on polymer modification of silica surfaces has mainly focused on obtaining functional composite particles in ways such as "grafting-to" and "grafting-from", such as temperature-responsive, light-responsive, or pH-responsive functions; or preparing core-shell structured composite nanoparticles to endow silica with magnetic and catalytic properties. There are relatively few examples of using block copolymers to form films to modify silica nanoparticles to endow silica with interfacial compatibility as in the present invention. Summary of the Invention
[0004] Aiming at the deficiencies of the prior art, the present invention provides a block copolymer-coated silica material and a preparation method thereof. First, a macromolecular chain transfer agent with a specific degree of polymerization is obtained by reversible addition-fragmentation chain transfer (RAFT) polymerization method. Then, silica particles with double bonds on the surface are obtained by modifying silica with a silane coupling agent containing a carbon-carbon double bond. Finally, silica, the macromolecular chain transfer agent, and another monomer are polymerized in one pot, so that a block copolymer is formed and forms a film on the silica surface. The polymer film has the characteristics of adjustable stable chain length and controllable film thickness. And it can uniformly coat the silica nanoparticles to form a block copolymer-silica nanocomposite with a core-shell structure.
[0005] To achieve the above object, the present invention is realized through the following technical solutions:
[0006] The present invention discloses a block copolymer-coated silica material, and the material has a core-shell structure with silica nanoparticles as the core and a block copolymer as the shell.
[0007] Preferably, the particle size of the silica nanoparticles is 50-500 nm, and the thickness of the block copolymer is 5-100 nm.
[0008] Correspondingly, a preparation method of a block copolymer-coated silica material disperses silica nanoparticles modified with a silane coupling agent, a polymethacrylic acid macro chain transfer agent, a benzyl methacrylate monomer, and an initiator 4,4'-azobis(4-cyanopentanoic acid) in a mixed solution of ethanol and water. After heating and stirring, a block copolymer-coated silica nanocomposite material is formed.
[0009] Preferably, the stirring reaction is carried out in an oil bath at 70°C for 24 h, and the stirring speed is 300 rpm.
[0010] Preferably, the degree of polymerization of the polymethacrylic acid macro chain transfer agent is 30-500, the mass ratio of the benzyl methacrylate monomer, the polymethacrylic acid macro chain transfer agent, and the initiator is 280-500:40-60:1, and the mass ratio of the benzyl methacrylate monomer to the mixed solution is 1:20-35.
[0011] Preferably, the preparation process of the silica nanoparticles modified with a silane coupling agent is as follows: tetraethyl orthosilicate is added to a mixed solution of ethanol, water, and ammonia water. After stirring and reacting, silica nanoparticles are obtained, and then γ-(methacryloyloxy)propyltrimethoxysilane is added and stirring reaction continues to obtain γ-(methacryloyloxy)propyltrimethoxysilane-modified silica nanoparticles.
[0012] Preferably, the mass ratio of ethanol, water, ammonia water, and tetraethyl orthosilicate is 8-40:3-15:1-5:1, and the mass ratio of tetraethyl orthosilicate to MPS is 2-3:1.
[0013] Preferably, the reaction temperature for preparing the silica nanoparticles is room temperature, and the reaction time is 4 h; the reaction temperature for γ-(methacryloyloxy)propyltrimethoxysilane to modify the silica nanoparticles is 70°C, and the reaction time is 24 h.
[0014] Preferably, the preparation process of the polymethacrylic acid macro chain transfer agent is as follows: methacrylic acid monomers, a chain transfer agent, and an initiator are added to a solvent, and polymerization is carried out in an inert atmosphere to form a macro chain transfer agent;
[0015] The chain transfer agent is 4-cyano-4-(phenylcarbonylthio) pentanoic acid, and the initiator is 4,4'-azobis(4-cyanopentanoic acid).
[0016] Preferably, the mass ratio of the methacrylic acid monomer, the chain transfer agent and the initiator is 60-110:5:1, the solvent is ethanol, and the mass ratio of the methacrylic acid monomer to the solvent is 2-3:4.
[0017] The present invention has the following beneficial effects:
[0018] 1. The present invention provides a simple method to introduce silica nanoparticles with reactive surfaces on the basis of block copolymer synthesis, and coat diblock copolymers on the surface of silica nanoparticles during the polymerization reaction to obtain a block copolymer-coated silica composite material with a core-shell structure. This method endows silica with the properties of polymers, obtains a colloidal emulsion with good hydrophilicity and dispersibility, and solves the problem of easy aggregation of silica as an additive.
[0019] 2. The present invention can prepare macromolecular chain transfer agents with different stable chain lengths by reversible addition-fragmentation chain transfer polymerization, and can easily adjust the thickness of the block copolymer film by changing the degree of polymerization of another monomer. Therefore, the stable chain length and the degree of polymerization of the block copolymer can be systematically changed to obtain composite nanoparticles of polymer-coated silica with a core-shell structure. Description of the Drawings
[0020] Figure 1 Transmission electron microscope image of the SiO 2 nanoparticles prepared in Example 3;
[0021] Figure 2 Transmission microscope image of the SiO 2 -M 37 B 250 prepared in Example 4;
[0022] Figure 3 Transmission microscope image of the SiO 2 -M 60 B 250 prepared in Example 5;
[0023] Figure 4 Transmission microscope image of the SiO 2 -M 60 B 150 prepared in Example 6;
[0024] Figure 5 Transmission microscope image of the SiO 2 -M60 B 250 Transmission microscope image of
[0025] Figure 6 SiO prepared in Comparative Example 4 2 -M 60 B 250 Transmission microscope image of
[0026] Figure 7 SiO prepared in Comparative Example 6 2 -M 60 B 90 Transmission microscope image. Detailed implementation manners
[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention. Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.
[0028] 1. The present invention discloses a block copolymer-coated silica material, and the material has a core-shell structure with silica nanoparticles as the core and a block copolymer as the shell. The particle size of the silica nanoparticles is 50-500 nm, and the thickness of the block copolymer is 5-100 nm.
[0029] 2. The present invention also discloses a preparation method of a block copolymer-coated silica material. The silica nanoparticles modified with a silane coupling agent, a poly(methacrylic acid) (PMAA) macro chain transfer agent, a benzyl methacrylate (BzMA) monomer, and an initiator 4,4'-azobis(4-cyanovaleric acid) are dispersed in a mixed solution of ethanol and water, and a block copolymer-coated silica nanocomposite is formed after heating and stirring.
[0030] Specifically: The reaction is carried out in an oil bath at 70 °C, and the stirring reaction is carried out for 24 h with a stirring speed of 300 rpm. The degree of polymerization of the PMAA macro chain transfer agent is 37-60, the mass ratio of the benzyl methacrylate monomer, the PMAA macro chain transfer agent, and the initiator is 280-500:40-60:1, the mass ratio of ethanol to water is 2-3:1, the mass ratio of the monomer to the mixed solvent is 1:20-35, and the mass ratio of silica to the mixed solution is 1:40-50.
[0031] Further, the preparation process of the silica nanoparticles modified with silane coupling agent is as follows: tetraethyl orthosilicate is added to a mixed solution of ethanol, water and ammonia water, and after stirring and reacting, silica nanoparticles are obtained. Then γ-(methacryloyloxy)propyltrimethoxysilane (MPS) is added and stirring reaction continues to obtain MPS-modified silica nanoparticles. After the reaction ends, it is washed with ethanol and centrifuged several times.
[0032] Among them, the mass ratio of ethanol, water, ammonia water and tetraethyl orthosilicate is 8-40:3-15:1-5:1, and the mass ratio of tetraethyl orthosilicate to MPS is 2-3:1. The reaction temperature of the silica nanoparticles is room temperature, and the reaction time is 4 h; the reaction temperature for MPS to modify silica nanoparticles is 70 °C, and the reaction time is 24 h.
[0033] Further, the preparation process of the poly(methacrylic acid) (PMAA) macromolecular chain transfer agent is as follows: methacrylic acid monomer, chain transfer agent and initiator are added to a mixed solvent, and after purging with inert gas to remove oxygen, the monomer is polymerized by the initiator to form a macromolecular chain transfer agent;
[0034] Among them, the chain transfer reagent is 4-cyano-4-(phenylcarbonylthio)valeric acid, and the initiator is 4,4'-azobis(4-cyanovaleric acid). The mass ratio of the methacrylic acid monomer, chain transfer agent and initiator is 60-110:5:1, the solvent is ethanol, and the mass ratio of the methacrylic acid monomer to the solvent is 2-3:4. Nitrogen is purged to remove oxygen for 30 min in an ice-water bath, and the reaction is carried out in a 70 °C oil bath for 3 h.
[0035] The present invention will be further described below in conjunction with specific embodiments.
[0036] Example 1
[0037] Poly(methacrylic acid) (PMAA) 37 The preparation process of the macromolecular chain transfer agent is as follows:
[0038] 20 g of methacrylic acid, 1.6 g of 4-cyano-4-(phenylcarbonylthio)valeric acid, 0.32 g of 4,4'-azobis(4-cyanovaleric acid) ACVA and 30 g of anhydrous ethanol are added to a 250 mL round-bottom flask. Nitrogen is purged for 30 min in an ice-water bath to remove oxygen, and then the reaction is carried out in a 70 °C oil bath for 3 h. The product is purified by precipitation by dropping in diethyl ether. The obtained product is the poly(methacrylic acid) (PMAA) macromolecular chain transfer agent. The average degree of polymerization is calculated to be 37 by nuclear magnetic resonance hydrogen spectrum. The macromolecular chain transfer agent with this degree of polymerization is denoted as M 37 .
[0039] Example 2
[0040] Polymethacrylic acid (PMAA) 60 The preparation process of the macromolecular chain transfer agent is as follows:
[0041] 15 g of methacrylic acid, 0.70 g of 4-cyano-4-(phenylcarbonylthio) pentanoic acid, 0.14 g of 4,4'-azobis(4-cyanopentanoic acid) ACVA and 24 g of absolute ethanol were added to a 250 mL round-bottom flask. Nitrogen was introduced for 30 min in an ice-water bath to remove oxygen, and then the mixture was placed in an oil bath at 70 °C and reacted for 3 h. The product was purified by precipitation in diethyl ether. The polymethacrylic acid (PMAA) macromolecular chain transfer agent was obtained. The average degree of polymerization was calculated to be 60 by 1H NMR, and the macromolecular chain transfer agent with this degree of polymerization was denoted as M 60 .
[0042] Example 3
[0043] The preparation process of silica and the surface-modified silane coupling agent MPS is as follows:
[0044] 5.0 mL of tetraethyl orthosilicate was dissolved in 20 g of ethanol and stirred for 10 minutes; then, this solution was quickly added to a mixed solution containing 20 g of ethanol, 15 g of water and 5.0 mL of ammonia water. The reaction was carried out at room temperature for 3.5 h to obtain silica nanoparticles (see the transmission electron micrograph in Figure 1 ). Then, 2.0 mL of γ-(methacryloyloxy) propyltrimethoxysilane was added, and the mixture was stirred and reacted in an oil bath at 70 °C for 24 h to obtain MPS-modified silica nanoparticles (SiO 2 -MPS). After the reaction, it was washed and centrifuged several times with ethanol. It should be noted that: by changing the ratio of tetraethyl orthosilicate to ethanol, the size of the silica particles can be adjusted.
[0045] Example 4
[0046] The preparation process of the composite material of block copolymer-coated silica is as follows:
[0047] 18 mg of poly(methacrylic acid) 37 macromolecular chain transfer agent (M 60 ), 220 mg of benzyl methacrylate (BzMA), 0.1 g of SiO 2 -MPS and 0.45 mg of 4,4'-azobis(4-cyanopentanoic acid) were added to a round-bottom flask containing a mixed solvent of 4.5 g of ethanol and water (the mass ratio of ethanol to water was 2:1). Nitrogen was introduced for 30 min in an ice-water bath to remove oxygen, and the mixture was placed in an oil bath at 70 °C and reacted for 24 h to obtain the diblock copolymer poly(methacrylic acid) 37 -poly(benzyl methacrylate) 250 coated silica composite nanoparticles, denoted as SiO2 -M 37 B 250 。SiO 2 -M 37 B 250 The transmission microscope image of Figure 2 is as shown. For SiO 2 the particle size is 240 - 280 nm and the block copolymer thickness is 40 - 70 nm.
[0048] Example 5
[0049] The preparation process of the composite material with block copolymer coated silica is as follows:
[0050] 27 mg of poly(methacrylic acid) 60 macromolecular chain transfer agent (M 60 ), 220 mg of benzyl methacrylate (BzMA), 0.1 g of SiO 2 -MPS and 0.45 mg of 4,4'-azobis(4-cyanovaleric acid) were added to a round-bottom flask containing 4.5 g of a mixed solvent of ethanol and water (the mass ratio of ethanol to water is 2:1). Nitrogen was passed through for 30 min in an ice-water bath for deoxygenation, and the reaction was carried out in an oil bath at 70 °C for 24 h to obtain the diblock copolymer poly(methacrylic acid) 60 -poly(benzyl methacrylate) 250 coated silica composite nanoparticles, denoted as SiO 2 -M 60 B 250 。SiO 2 -M 60 B 250 The transmission microscope image of Figure 3 is as shown. For SiO 2 the particle size is 240 - 280 nm and the block copolymer thickness is 40 - 70 nm.
[0051] Example 6
[0052] The preparation process of the composite material with block copolymer coated silica is as follows:
[0053] 27 mg of poly(methacrylic acid) 60 macromolecular chain transfer agent (M 60 ) and 132 mg of benzyl methacrylate (BzMA), 0.1 g of SiO 2 -MPS and 0.45 mg of 4,4'-azobis(4-cyanovaleric acid) were added to a round-bottom flask containing 4.5 g of a mixed solvent of ethanol and water (the mass ratio of ethanol to water is 2:1). Nitrogen was passed through for 30 min in an ice-water bath for deoxygenation, and the reaction was carried out in an oil bath at 70 °C for 24 h to obtain the diblock copolymer poly(methacrylic acid) 60-Poly(benzyl methacrylate) 150 Coated silica composite nanoparticles, denoted as SiO 2 -M 60 B 150 。The transmission electron microscopy image of SiO 2 -M 60 B 150 is as shown in Figure 4 . The particle size of SiO 2 is 240 - 280 nm, and the thickness of the block copolymer is 15 - 40 nm.
[0054] Comparative Example 1
[0055] Same as Example 4, except that: by replacing the macromolecular chain transfer agent M 60 with 1.4 mg of 4-cyano-4-(phenylcarbonylthio)pentanoic acid, the transmission electron microscopy image is shown in Figure 5 . It can be seen from Figure 5 that the particle size of SiO 2 is 240 - 280 nm, and the thickness of the block copolymer is 0 nm. Under these conditions, a composite material with a block copolymer film-coated silica cannot be obtained.
[0056] Comparative Example 2
[0057] Same as Example 4, except that: replacing SiO 2 -MPS with silica, the transmission electron microscopy image of the result is shown in Figure 6 . The particle size of SiO 2 is 240 - 280 nm, and the thickness of the block copolymer is 0 nm. Under these conditions, a composite material with a block copolymer film-coated silica cannot be obtained.
[0058] Comparative Example 3
[0059] Same as Example 6, except that: when the degree of polymerization of the benzyl methacrylate monomer is reduced to 90, that is, when the mass of BzMA added is 79 mg, the result is as shown in the transmission electron microscopy image of Figure 7 . The particle size of SiO 2 is 240 - 280 nm, and the thickness of the block copolymer is 0 nm. Under these conditions, a composite material with a block copolymer film-coated silica with an obvious thickness cannot be obtained.
[0060] The above-described embodiments are only descriptions of the preferred embodiments of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.
Claims
1. A block copolymer coated silica material, characterized in that: The material is a core-shell structure with silicon dioxide nanoparticles as the core and block copolymer as the shell.
2. The block copolymer-coated silica material according to claim 1, characterized in that: The particle size of the silicon dioxide nanoparticles is 50 to 500 nm, and the thickness of the block copolymer is 5 to 100 nm.
3. A method for preparing the block copolymer-coated silica material according to claim 1 or 2, characterized in that: Silane coupling agent modified silica nanoparticles, polymethacrylic acid macromolecular chain transfer agent, benzyl methacrylate monomer and initiator 4,4'-azobis(4-cyanovaleric acid) are dispersed in a mixed solution of ethanol and water, and heated and stirred to form a block copolymer coated silica nanocomposite material.
4. The preparation method according to claim 3, characterized in that: The reaction was stirred in an oil bath at 70°C for 24 h at a stirring speed of 300 rpm.
5. The preparation method according to claim 3, characterized in that: The polymerization degree of the polymethacrylic acid macromolecular chain transfer agent is 30-500, the mass ratio of the methacrylate benzyl ester monomer, the polymethacrylic acid macromolecular chain transfer agent and the initiator is 280-500:40-60:1, and the mass ratio of the methacrylate benzyl ester monomer to the mixed solution is 1:20-35.
6. The preparation method according to claim 3, characterized in that: The preparation process of the silicon dioxide nanoparticles modified by the silane coupling agent is as follows: tetraethyl orthosilicate is added to a mixed solution of ethanol, water and ammonia water, and the silicon dioxide nanoparticles are obtained after stirring and reacting, and then γ-(methacryloyloxy)propyltrimethoxysilane is added and the stirring and reaction are continued to obtain the silicon dioxide nanoparticles modified by γ-(methacryloyloxy)propyltrimethoxysilane.
7. The preparation method according to claim 6, characterized in that: The mass ratio of the ethanol, water, ammonia water and tetraethyl orthosilicate is 8-40:3-15:1-5:1, and the mass ratio of tetraethyl orthosilicate to MPS is 2-3:
1.
8. The preparation method according to claim 6, characterized in that: The reaction temperature for preparing the silica nanoparticles is room temperature, and the reaction time is 4 hours; the reaction temperature for preparing the γ-(methacryloyloxy)propyltrimethoxysilane-modified silica nanoparticles is 70° C., and the reaction time is 24 hours.
9. The preparation method according to claim 3, characterized in that: The preparation process of the polymethacrylic acid macromolecular chain transfer agent is as follows: methacrylic acid monomer, chain transfer agent and initiator are added to a solvent, and polymerized under an inert atmosphere to form a macromolecular chain transfer agent; The chain transfer agent is 4-cyano-4-(phenylcarbonylthio)pentanoic acid, and the initiator is 4,4'-azobis(4-cyanovaleric acid).
10. The preparation method according to claim 9, characterized in that: The mass ratio of the methacrylic acid monomer, the chain transfer agent and the initiator is 60-110:5:1, the solvent is ethanol, and the mass ratio of the methacrylic acid monomer to the solvent is 2-3:4.
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