Perfluoropolyether-modified silicon dioxide material and preparation method therefor

Abstract

The present invention provides a perfluoropolyether modified silicon dioxide material and a preparation method therefor. The preparation method comprises: adding a functionalized fluorine-containing polymer to a first solvent, adding a silane coupling agent and a catalyst and reacting, and obtaining a functionalized fluorine-containing polymer-modified siloxane; adding silicon dioxide to a second solvent and water, and then adding the functionalized fluorine-containing polymer-modified siloxane, a main catalyst, and a co-catalyst and reacting, and obtaining a crude product of a functionalized fluorine-containing polymer-modified silicon dioxide; and desolvating the crude product and drying, to then obtain a perfluoropolyether-modified silicon dioxide material. The technical solution of the present invention solves the problems of traditional silicon dioxide such as the large number of hydroxyl groups on the surface thereof, being prone to agglomeration in materials, uneven dispersion, and poor compatibility with substrates, improves the compatibility of silicon dioxide materials with substrates, and promotes dispersion. Moreover, reactive groups on the surface thereof can achieve in-situ chemical crosslinking or in-situ synthesis with other materials, thus, the range of application is broader.

Description

A perfluoropolyether modified silica material and preparation method thereof

[0001] Cross-reference information

[0002] This application claims priority to the Chinese patent application filed with the China Patent Office on November 23, 2023, with application number 202311576467.6 and invention name “A perfluoropolyether modified silica material and its preparation method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0003] The invention relates to a perfluoropolyether modified silicon dioxide material and a preparation method thereof, belonging to the technical field of silicon dioxide material modification. Background Art

[0004] Silicon dioxide (SiO2) is an inorganic compound with irregular Si-O crystals inside. It is non-toxic and odorless, has a small particle size, a large specific surface area, good insulation, and high-temperature resistance. It is widely used in rubber and plastic materials, dyes and coatings, papermaking, and fine chemicals. However, because SiO2 contains a large number of silanol (Si-OH) groups on its surface, these groups give it a high surface energy, which easily leads to hydrogen bonds between particles, causing SiO2 to agglomerate and form aggregates. Furthermore, these hydroxyl groups are highly hydrophilic, resulting in poor compatibility with polymer materials and uneven dispersion, making it difficult to meet the needs of higher and more complex applications.

[0005] Currently, the most commonly used surface chemical modification method to deplete silica surface hydroxyl groups, improve its dispersibility, and enhance compatibility with polymer matrices is silane coupling agent modification, such as CN104445218A. Siloxane coupling agents have two groups with different chemical properties: one end is polar and can bind to small inorganic molecules, while the other end is non-polar and can bind to large organic molecules, making it a link between organic matter and small molecule particles. However, silicone materials have poor media resistance and are inherently oleophilic, making them susceptible to adsorbing oily dirt, which affects the cleanliness of the material surface.

[0006] Perfluoropolyether (PFPE) is a perfluoropolymer composed of CF bonds, CO bonds and CC bonds. It has remarkable properties such as low friction coefficient, wide temperature range (-100℃ to +300℃), high thermal stability, low surface energy (as low as 10-14mN / m) and excellent chemical inertness. It is widely used in aerospace, oil and gas exploration and production, petrochemical and other fields, especially under extreme working conditions. It is a reliable wear-reducing and lubricating material. However, PFPE is incompatible with non-fluorine materials, which limits its application in many fields.

[0007] Summary of the Invention

[0008] In order to solve the above technical problems, the purpose of the present invention is to provide a modified silica material and a preparation method thereof. Through chemical grafting modification, a reactive perfluoropolyether-based polymer is grafted onto the SiO2 surface, which not only consumes the hydroxyl groups on the SiO2 surface, but also improves its dispersibility in polymer materials.

[0009] To achieve the above object, the present invention provides a method for preparing a perfluoropolyether modified silica material, which comprises the following steps:

[0010] (a) adding a functionalized fluoropolymer to a first solvent, and then adding a silane coupling agent and a catalyst to react to obtain a functionalized fluoropolymer-modified siloxane, wherein the molar ratio of the functionalized fluoropolymer to the silane coupling agent is 1:1-6;

[0011] (b) adding silica to a second solvent and water, and then adding the functionalized fluorinated polymer-modified siloxane, a main catalyst, and a co-catalyst to react to obtain a crude product of the functionalized fluorinated polymer-modified silica, wherein the mass ratio of the silica to the functionalized fluorinated polymer-modified siloxane is 1-50:1;

[0012] (c) removing the solvent from the crude product and drying it to obtain a perfluoropolyether modified silica material.

[0013] According to a specific embodiment of the present invention, preferably, the structure of the functionalized fluorine-containing polymer is R f -bR; where R f It is perfluoropolyether and its derivatives, and R is polysiloxane.

[0014] According to a specific embodiment of the present invention, preferably, the perfluoropolyether includes but is not limited to one or a combination of two or more of K-type perfluoropolyether, D-type perfluoropolyether, Y-type perfluoropolyether and Z-type perfluoropolyether.

[0015] According to a specific embodiment of the present invention, preferably, the perfluoropolyether derivative includes but is not limited to one or a combination of two or more of perfluoropolyether vinyl ether, perfluoropolyether carboxylic acid, perfluoropolyether methyl ester, etc.

[0016] In the above preparation method, preferably, the polysiloxane comprises one or a combination of two or more of hydrogen-containing silicone oil, mercapto-containing silicone oil, and amino-containing silicone oil;

[0017] The hydrogen-containing silicone oil includes one or a combination of two or more of single-ended silicon hydrogen silicone oil, double-ended silicon hydrogen silicone oil, and side silicon hydrogen silicone oil;

[0018] The mercapto-containing silicone oil includes one or a combination of terminal mercapto silicone oil and pendant mercapto silicone oil;

[0019] The amino-containing silicone oil includes one or a combination of terminal amino silicone oil and pendant amino silicone oil.

[0020] According to a specific embodiment of the present invention, preferably, the first solvent is a fluorocarbon solvent. More preferably, the fluorocarbon solvent includes but is not limited to one or a combination of two or more of perfluorocyclic ethers, hydrofluoroethers, 1,3-bis(trifluoromethyl)benzene, etc.

[0021] According to a specific embodiment of the present invention, preferably, in step (a), the catalyst includes but is not limited to one or a combination of two or more of Custer catalyst, benzoyl peroxide, di-tert-butyl peroxide, Pt / C, etc.

[0022] According to a specific embodiment of the present invention, preferably, in step (a), the amount of the catalyst used is 0.01%-10% of the total mass of the reaction materials, more preferably 0.05%-3.5%.

[0023] According to a specific embodiment of the present invention, preferably, in step (a), the silane coupling agent includes but is not limited to vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane, propenyltriethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, methylacryldimethoxysilane, methylacryldiethoxysilane, aminopropylvinyldimethoxysilane, aminopropylvinyldiethoxysilane, vinyldimethylchlorosilane, etc., or a combination of two or more thereof.

[0024] According to a specific embodiment of the present invention, preferably, in step (b), the main catalyst includes but is not limited to one or a combination of two or more of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, formic acid, citric acid, acetic acid, trifluoroacetic acid, trifluoromethanesulfonic acid, etc.

[0025] According to a specific embodiment of the present invention, preferably, the co-catalyst includes but is not limited to one or a combination of two or more of dibutyltin dilaurate, ethylenediaminetetraacetic acid, zinc gluconate, magnesium stearate, potassium phthalamide, etc.

[0026] According to a specific embodiment of the present invention, preferably, in step (b), the amount of the main catalyst is 0.01%-5% (more preferably 0.05%-2.5%) of the total mass of the reaction materials, and the amount of the co-catalyst is 0.01%-5% (more preferably 0.01%-2.0%) of the total mass of the reaction materials.

[0027] According to a specific embodiment of the present invention, preferably, in step (a) and step (b), the reaction temperature is 25-300°C, and the reaction time is 1-72h. More preferably, the reaction temperature is 25-200°C, and the reaction time is 1-36h.

[0028] According to a specific embodiment of the present invention, preferably, in step (a), the molecular weight of the functionalized fluorine-containing polymer is 1000-80000 g / mol, more preferably 1000-8000 g / mol.

[0029] According to a specific embodiment of the present invention, preferably, in step (b), the particle size of the silicon dioxide is 0.005-5000 μm, more preferably 0.01-50 μm.

[0030] According to a specific embodiment of the present invention, preferably, in step (b), the second solvent includes but is not limited to one or a combination of two or more of ethanol, isopropanol, propylene glycol, ethylene glycol, acetone, acetonitrile, tetrahydrofuran, diethylene glycol dimethyl ether, diethyl ether, tert-butyl ether, etc.

[0031] The present invention also provides a perfluoropolyether modified silica material, which is prepared by the above method.

[0032] The present invention provides a method for preparing a perfluoropolyether-modified silica material. Through chemical grafting modification, a reactive perfluoropolyether-based polymer (functionalized fluoropolymer-modified siloxane) is grafted onto the SiO2 surface. This not only consumes the hydroxyl groups on the SiO2 surface, improving its dispersibility in polymer materials, but also addresses the poor compatibility and migration issues associated with PFPE, due to its unique fluorine-atom-encapsulated molecular chains. Furthermore, the reactive groups on the modified SiO2 surface enable in-situ synthesis or in-situ crosslinking with materials containing active groups, further broadening the application of SiO2 and possessing immeasurable economic value in high-tech fields.

[0033] The technical solution of the present invention solves the problems of traditional silica, such as a large number of hydroxyl groups on the surface, easy agglomeration in the material, uneven dispersion, and poor compatibility with the substrate. It improves the compatibility of the silica material with the substrate and promotes dispersion. At the same time, the reactive groups on its surface can achieve in-situ chemical crosslinking or in-situ synthesis with other materials, and has a wider range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 is the infrared spectrum of double-terminal hydrogen-containing perfluoropolyether-b-polysiloxane.

[0035] Figure 2 is the infrared spectrum of vinyltrimethoxysilane.

[0036] FIG3 is an infrared spectrum of the crude product (α-silyl hydrogen, ω-trimethoxysilane perfluoropolyether).

[0037] Figure 4 is an infrared spectrum of silicon dioxide.

[0038] FIG5 is an infrared spectrum of the crude product (α-silyl hydrogen, ω-trimethoxysilane perfluoropolyether) modified silica.

[0039] Figure 6 is the H-NMR spectrum of the crude product (α-silyl hydride, ω-trimethoxysilane perfluoropolyether) modified with silica.

[0040] FIG7 is a water contact angle test result of the modified silica-coated glass surface in Example 1.

[0041] FIG8 is a water contact angle test result of the modified silica-coated glass surface in Example 2.

[0042] FIG9 is a water contact angle test result of the modified silica-coated glass surface in Example 3.

[0043] FIG10 is a water contact angle test result of the modified silica-coated glass surface in Example 4.

[0044] FIG11 is a water contact angle test result of the modified silica-coated glass surface in Example 5.

[0045] FIG12 is the water contact angle test result of the modified silica-coated glass surface in Example 6.

[0046] FIG13 is a water contact angle test result of the unmodified silica-coated glass surface in the comparative example. DETAILED DESCRIPTION

[0047] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0048] In the specification and claims, "including" and "comprising" should be understood as meaning "including, but not limited to". The specific details disclosed are intended to make the present invention easier to understand. The use of one or more technical details by technicians in the relevant fields to implement this solution also belongs to the technical solution of the present invention.

[0049] Analysis and evaluation method: Perfluoropolyether-modified silica films were prepared on transparent glass surfaces using the Czochralski method. The contact angles of water and n-hexadecane were measured according to the international testing standard GB / T 24368-2009.

[0050] Particle size test: Malvern Zetasizer Nano ZS90 was used to test the particle size of silica before and after modification, with reference to the national standard GB / T 15445.2-2006.

[0051] The structure of bifunctional silyl perfluoropolyether-b-polysiloxane is shown below:

[0052] Example 1

[0053] This embodiment provides a perfluoropolyether modified silica material, the preparation method of which includes:

[0054] 20g of bifunctional silane perfluoropolyether-b-polysiloxane, 10mL of 1,3-bis(trifluoromethyl)benzene, and 20μL of Custer's catalyst were added to a three-necked flask and stirred for 30 minutes. Then, 3.7g of vinyltrimethoxysilane was added and the temperature was raised to 70°C for 12 hours to obtain a crude product. The infrared spectra are shown in Figures 1, 2, and 3. The structural formula of the crude product (α-silane perfluoropolyether, ω-trimethoxysilane) is shown below:

[0055] 50g of silica, 3g of deionized water, 100g of ethanol, 0.5g of trifluoromethanesulfonic acid and 0.1g of dibutyltin dilaurate were added to a three-necked flask and stirred at room temperature for 10 minutes. Then, the crude product obtained in the previous step was added and the temperature was raised to 60°C for reaction for 8 hours. After the reaction was completed, the solvent was filtered off and the filter cake was dried at 100°C to obtain the target product. The infrared spectra of the product are shown in Figures 4 and 5. 1 The H NMR spectrum is shown in Figure 6.

[0056] From the infrared spectra of Figures 4 and 5, it can be seen that after the fluorine-containing polymer is grafted onto the surface of silica by chemical means, the hydroxyl groups on the surface of silica are significantly reduced, and the infrared characteristic peak of Si-H appears. 1 The H NMR spectrum further confirms the successful preparation of the modified material. Figure 7 shows the water contact angle test results after the modified material was coated on the glass surface.

[0057] The structural formula of the target product is shown below:

[0058] Example 2

[0059] This embodiment provides a perfluoropolyether modified silica material, the preparation method of which includes:

[0060] 10 g of side-group hydrogen-containing perfluoropolyether-b-polysiloxane, 8 mL of perfluorocyclic ether and 0.5 g of benzoyl peroxide were added to a reactor and stirred for 10 min. Then 8.9 g of methylacryldiethoxysilane was added, and the temperature was raised to 150° C. and reacted for 5 h to obtain a crude product.

[0061] 40g of silica, 3g of deionized water, 120g of isopropyl alcohol, 1.0g of trifluoroacetic acid, and 0.2g of magnesium stearate were added to a reactor and stirred at room temperature for 6 minutes. The crude product from the previous step was then added and the temperature was raised to 260°C for 24 hours. After the reaction, the solvent was filtered out, and the filter cake was dried at 110°C to obtain the desired product. Figure 8 shows the water contact angle test results of the modified material after coating a glass surface.

[0062] Example 3

[0063] This embodiment provides a perfluoropolyether modified silica material, the preparation method of which includes:

[0064] 16 g of bifunctional silicon hydrogen perfluoropolyether-b-polysiloxane and 15 mL of hydrofluoroether were added to a reaction kettle and stirred for 5 minutes. Then, 3.3 g of vinyldimethylsilyl chloride was added and the temperature was raised to 200° C. and the reaction was carried out for 6 hours to obtain a crude product.

[0065] 80g of silica, 5g of deionized water, 250g of acetone, 0.2g of phosphoric acid, and 0.1g of potassium phthalamide were added to a reactor and stirred at room temperature for 5 minutes. The crude product from the previous step was then added and the temperature was raised to 240°C for 48 hours. After the reaction, the solvent was filtered out, and the filter cake was dried at 150°C to obtain the desired product. Figure 9 shows the water contact angle test results of the modified material after coating a glass surface.

[0066] Example 4

[0067] This embodiment provides a perfluoropolyether modified silica material, the preparation method of which includes:

[0068] 25 g of double-bond perfluoropolyether-b-polysiloxane and 35 mL of 1,3-bis(trifluoromethyl)benzene were added to a reaction kettle and stirred for 25 minutes. Then, 5.7 g of aminopropyltriethoxysilane was added, and the temperature was raised to 170° C. and reacted for 20 hours to obtain a crude product.

[0069] 45g of silica, 8g of deionized water, 150g of ethylene glycol, 0.5g of citric acid, and 0.2g of ethylenediaminetetraacetic acid were added to a reactor and stirred at room temperature for 5 minutes. The crude product from the previous step was then added and the temperature was raised to 100°C for 72 hours. After the reaction, the solvent was filtered out, and the filter cake was dried at 200°C to obtain the desired product. Figure 10 shows the water contact angle test results of the modified material after coating a glass surface.

[0070] Example 5

[0071] This embodiment provides a perfluoropolyether modified silica material, the preparation method of which includes:

[0072] 11 g of terminal acryloxy perfluoropolyether-b-polysiloxane and 60 mL of 1,3-bis(trifluoromethyl)benzene were added to a three-necked flask and stirred for 25 min. Then, 11.3 g of aminopropyltrimethoxysilane was added, and the temperature was raised to 50° C. and reacted for 72 h to obtain a crude product.

[0073] 70g of silica, 15g of deionized water, 110g of diethylene glycol dimethyl ether, 2.0g of oxalic acid, and 2.0g of zinc gluconate were added to a reactor and stirred at room temperature for 20 minutes. The crude product from the previous step was then added and the temperature was raised to 260°C for 36 hours. After the reaction, the solvent was filtered off, and the filter cake was dried at 200°C to obtain the desired product. Figure 11 shows the water contact angle test results of the modified material after coating a glass surface.

[0074] Example 6

[0075] This embodiment provides a perfluoropolyether modified silica material, the preparation method of which includes:

[0076] 37 g of hydrogen-containing perfluoropolyether-b-polysiloxane, 20 mL of 1,3-bis(trifluoromethyl)benzene and 2.0 g of di-tert-butyl peroxide were added to a reactor and stirred for 30 minutes. Then, 10.6 g of aminopropylvinyldiethoxysilane was added, and the temperature was raised to 160° C. and reacted for 36 hours to obtain a crude product.

[0077] 65g of silica, 22g of deionized water, 100g of tert-butyl ether, 5.0g of formic acid, and 0.2g of dibutyltin dilaurate were added to a reactor and stirred at room temperature for 5 minutes. The crude product from the previous step was then added and the temperature was raised to 200°C for 10 hours. After the reaction, the solvent was filtered off, and the filter cake was dried at 100°C to obtain the desired product. Figure 12 shows the water contact angle test results of the modified material after coating a glass surface.

[0078] Comparative Example

[0079] This comparative example is unmodified silica. Figure 13 shows the water contact angle test results of the glass surface coated with unmodified silica.

[0080] Table 1 shows the water and n-hexadecane contact angles and particle size test results of the perfluoropolyether-modified silica prepared in Examples 1-6.

[0081] Table 1 shows the contact angles of water and n-hexadecane and particle size of perfluoropolyether modified silica

[0082] The test results shown in Table 1 and Figures 7 to 13 above show that: f After the silica was modified with -bR, the water contact angle of the modified silica increased from 110° to 138-149°. f -bR has excellent low surface energy.

Claims

1. A method for preparing a perfluoropolyether-modified silica material, which comprises the following steps: (a) Adding a functionalized fluoropolymer into a first solvent, then adding a silane coupling agent and a catalyst for reaction to obtain a functionalized fluoropolymer-modified siloxane, wherein the molar ratio of the functionalized fluoropolymer to the silane coupling agent is 1:1 - 6; (b) Adding silica into a second solvent and water, then adding the functionalized fluoropolymer-modified siloxane, a main catalyst and a co-catalyst for reaction to obtain a crude product of the functionalized fluoropolymer-modified silica, wherein the mass ratio of the silica to the functionalized fluoropolymer-modified siloxane is 1 - 50:1; (c) After removing the solvent from the crude product and drying, a perfluoropolyether-modified silica material is obtained.

2. The method according to claim 1, wherein, The structure of the functionalized fluoropolymer is R f -b-R; Among them, R f is perfluoropolyether and its derivatives, and R is polysiloxane.

3. The method according to claim 2, wherein, The perfluoropolyether includes one or a combination of two or more of K-type perfluoropolyether, D-type perfluoropolyether, Y-type perfluoropolyether, and Z-type perfluoropolyether.

4. The method according to claim 3, wherein, The perfluoropolyether derivative includes one or a combination of two or more of perfluoropolyether vinyl ether, perfluoropolyether carboxylic acid, and perfluoropolyether methyl ester.

5. The method according to claim 2, wherein, The polysiloxane includes one or a combination of two or more of hydrogen-containing silicone oil, mercapto-containing silicone oil, and amino-containing silicone oil; The hydrogen-containing silicone oil includes one or a combination of two or more of mono-terminal silicon hydride silicone oil, di-terminal silicon hydride silicone oil, and side-chain silicon hydride silicone oil; The mercapto-containing silicone oil includes one or a combination of two of terminal mercapto silicone oil and side-chain mercapto silicone oil; The amino-containing silicone oil includes one or a combination of two of terminal amino silicone oil and side-chain amino silicone oil.

6. The method according to claim 1, wherein, The first solvent is a fluorocarbon solvent.

7. The method according to claim 6, wherein, The fluorocarbon solvent includes one or a combination of two or more of perfluorocyclic ether, hydrofluoroether, and 1,3-bis(trifluoromethyl)benzene.

8. The method according to claim 1, wherein, In step (a), the catalyst includes one or a combination of two or more of Karstedt catalyst, benzoyl peroxide, di-tert-butyl peroxide, and Pt / C.

9. The method according to claim 1, wherein, In step (a), the dosage of the catalyst is 0.01% - 10% of the total mass of the reaction materials.

10. The method according to claim 1, wherein, In step (a), the silane coupling agent includes one or a combination of two or more of vinyltrimethoxysilane, vinyltriethoxysilane, propenyltrimethoxysilane, propenyltriethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, methacrylyldimethoxysilane, methacrylyldiethoxysilane, aminopropylvinyldimethoxysilane, aminopropylvinyldiethoxysilane, and vinyldimethylchlorosilane.

11. The method according to claim 1, wherein, In step (b), the main catalyst includes one or a combination of two or more of hydrochloric acid, sulfuric acid, phosphoric acid, oxalic acid, formic acid, citric acid, acetic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid; The cocatalyst includes one or a combination of two or more of dibutyltin dilaurate, ethylenediaminetetraacetic acid, zinc gluconate, magnesium stearate, and potassium phthalimide.

12. The method according to claim 1, wherein, In step (b), the dosage of the main catalyst is 0.01%-5% of the total mass of the reaction materials, and the dosage of the cocatalyst is 0.01%-5% of the total mass of the reaction materials.

13. The method according to claim 1, wherein, In steps (a) and (b), the reaction temperature is 25-300 °C, and the reaction time is 1-72 h.

14. The method according to claim 1, wherein, In step (a), the molecular weight of the functionalized fluoropolymer is 1000-80000 g / mol.

15. The method according to claim 1, wherein, In step (b), the particle size of the silica is 0.005-5000 μm.

16. The method according to claim 1, wherein, In step (b), the second solvent includes one or a combination of two or more of ethanol, isopropanol, propylene glycol, ethylene glycol, acetone, acetonitrile, tetrahydrofuran, diethylene glycol dimethyl ether, ether, and tert-butyl ether.

17. A perfluoropolyether-modified silica material prepared by the method according to claim 1.

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