Method for realizing hydrophobicity and oleophobicity of aerogel material through two-step method

Abstract

The invention discloses a method for realizing hydrophobicity and oleophobicity of an aerogel material by a two-step method, which is characterized in that the aerogel is modified by a two-step method of gas phase treatment and liquid phase treatment by taking perfluorosilane as a modifier. A hydrophobic and oleophobic layer with a certain thickness can be formed on the surface of an aerogel material framework through gas phase treatment, and in the next liquid phase treatment process, the hydrophobic and oleophobic layer can play a role in induction and promote polymerization and deposition of a modifier on the aerogel framework, so that the hydrophobic and oleophobic layer which compactly coats the framework is finally formed. The preparation method has the characteristics of wide applicability, no need of activating treatment and the like, can endow the aerogel material with good hydrophobic and oleophobic properties, and improves the stain resistance and water resistance of the aerogel material.

Description

Technical Field

[0001] The invention relates to a two-step method for achieving hydrophobicity and oleophobicity of an aerogel material, belongs to the field of aerogel modification, and can improve the anti-fouling and water-resistance capabilities of the aerogel material. Background Art

[0002] Aerogel is a nanoporous material formed by the accumulation of nanoparticles. It has the characteristics of low density and good thermal insulation. It is widely used in new energy, aerospace, shipbuilding and other fields. Aerogel has a rich nanoporous structure and a specific surface area of ​​up to 1000m 2 / g or more, and there are many residual hydrophilic groups on the skeleton surface. During storage and use, the aerogel will be exposed to moisture in the air, oil stains in the machining process, etc. These liquids will form a liquid film with huge surface tension in the nanopores of the aerogel, which will destroy the pore structure of the aerogel and affect its thermal insulation performance. Therefore, in order to achieve long-term storage and stable use of aerogel, it is very important to treat the aerogel with hydrophobicity and oleophobicity.

[0003] Aerogel surface post-treatment is the most commonly used hydrophobic and oleophobic modification method, that is, after the aerogel is prepared, the aerogel is treated in gas phase or liquid phase to make it hydrophobic and oleophobic. Traditional aerogel hydrophobic and oleophobic treatment methods rely heavily on active groups such as hydroxyl groups on the surface of the aerogel. During the gas phase or liquid phase hydrophobic process, the modification reagent combines with the active groups on the surface of the aerogel to form a stable protective layer, thereby giving the aerogel a good hydrophobic and oleophobic effect. Patent application CN111073510A describes a method for hydrophobic and oleophobic modification of low-density transparent silica aerogel using perfluorosilane reagents and ammonia methanol gas phase treatment to improve the fingerprint anti-pollution ability of the aerogel. Patent application CN114920290A introduces a modification method for immersing or fumigating zirconium dioxide aerogel using hexamethyldisilazane, methyltriethoxysilane, and methyltrimethoxysilane as modifiers, which can prepare zirconium dioxide aerogel with good hydrophobicity. Cervin et al. used octyltrichlorosilane as a modifier to perform chemical vapor deposition on cellulose aerogels, which can achieve super-hydrophobicity of cellulose aerogels (Cervin NT, Aulin C, Larsson PT, et al. Ultra porous nanocellulose aerogels as separation medium for mixtures of oil / water liquids [J]. Cellulose, 2012, 19 (2): 401-410). The hydrophobic and oleophobic modification of aerogels currently has the following defects:

[0004] (1) Existing modification methods rely on the active groups on the surface of aerogels and have poor applicability;

[0005] (2) The modified groups are unevenly distributed in the aerogel, resulting in poor performance;

[0006] (3) Existing modification methods focus on the hydrophobic properties of aerogels, while neglecting the oleophobic properties. Summary of the invention

[0007] In order to improve the above-mentioned method of making aerogels hydrophobic and oleophobic, the present invention provides a two-step method for achieving hydrophobic and oleophobic properties of aerogels, which can give aerogels super hydrophobic and oleophobic properties, making up for the defect of insufficient hydrophobic and oleophobic properties of aerogels in traditional single modification methods, and can improve the anti-fouling and water resistance of aerogel materials, and greatly reduce the damage of aerogel materials during storage or use.

[0008] To achieve the above object, the specific technical solution of the present invention is a two-step method for achieving hydrophobic and oleophobic properties of aerogels, comprising the following steps:

[0009] A two-step method for achieving hydrophobicity and oleophobicity of aerogel materials, comprising the following steps:

[0010] The aerogel is modified by gas phase treatment using a perfluorinated modifier to form a hydrophobic and oleophobic layer on the surface of the aerogel;

[0011] The aerogel after gas phase treatment is subjected to liquid phase treatment by using a perfluorinated modifier solution to form a hydrophobic and oleophobic layer densely covering the aerogel.

[0012] Furthermore, the aerogel is modified by gas phase treatment using a perfluorinated modifier, comprising:

[0013] (1) preparing an aerogel material to be treated with hydrophobic and oleophobic treatment;

[0014] (2) placing the aerogel material in a sealed container containing a perfluorinated modifier;

[0015] (3) evacuating the container in (2) and heating it in an oven;

[0016] (4) Pour pure water into the container in (3) and continue heating;

[0017] (5) Take the container in (4) out of the oven and cool it to room temperature, then take out the aerogel material.

[0018] Furthermore, a screen is provided inside the sealed container, aerogel is placed on the screen, and a perfluorinated modifier is placed below the screen and at the bottom of the container.

[0019] Furthermore, the aerogel after the gas phase treatment is subjected to liquid phase treatment using a perfluorinated modifier solution, comprising:

[0020] (6) preparing a perfluorinated modifier solution;

[0021] (7) soaking the aerogel material obtained in (5) into the perfluorinated modifier solution in (6);

[0022] (8) The aerogel material in (7) is taken out from the perfluorinated modifier solution, left to air-dry, and heated to dry until the weight does not change, thereby finally obtaining a hydrophobic and oleophobic aerogel material.

[0023] Furthermore, the acid catalyst used in preparing the perfluorinated modifier solution may be one or more weak acids such as glacial acetic acid, oxalic acid, and benzoic acid.

[0024] Furthermore, the perfluoro modifier can be one or more perfluoro modifiers such as 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane.

[0025] Furthermore, the mass of the perfluorinated modifier used in the gas phase treatment is 1% to 10% of the mass of the aerogel.

[0026] Furthermore, the mass of the perfluorinated modifier used in the liquid phase treatment is 10% to 50% of the mass of the aerogel.

[0027] Furthermore, the temperature range of the gas phase treatment is 90°C to 150°C.

[0028] Furthermore, the mass of pure water used in the gas phase treatment is 10% to 50% of the mass of the perfluorinated modifier.

[0029] The present invention also provides a hydrophobic and oleophobic aerogel material prepared according to the method.

[0030] The principle of the present invention is that during the gas phase treatment process, the perfluorinated modifier will react with the residual active groups of the aerogel material itself and anchor to the surface of the aerogel skeleton, and will hydrolyze and self-polymerize with water vapor and deposit on the surface of the aerogel skeleton. After the gas phase treatment, a hydrophobic and oleophobic layer of a certain thickness will be formed on the surface of the aerogel material skeleton. In the next liquid phase treatment process, these hydrophobic and oleophobic layers can play an inductive role and promote the polymerization and deposition of the perfluorinated modifier on the aerogel skeleton, thereby finally forming a hydrophobic and oleophobic layer that densely coats the skeleton.

[0031] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0032] 1. The present invention does not require the aerogel material to be activated in advance, and the modification process can be performed directly.

[0033] 2. The present invention can achieve uniform coating of the modifier on the aerogel skeleton, improve the hydrophobic and oleophobic effects, and improve the anti-fouling and water resistance of the aerogel material.

[0034] 3. The present invention is applicable to a variety of aerogel systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of a hydrophobic and oleophobic gas phase treatment container in an embodiment;

[0036] Figure 2 This is a scanning electron microscope image of the alumina aerogel material after the hydrophobic and oleophobic treatment in Example 1;

[0037] Figure 3 This is a diagram showing the alumina aerogel material in Example 1 after the hydrophobic and oleophobic treatment. DETAILED DESCRIPTION

[0038] The following is combined with Figures 1 to 3 The present invention is further described with examples:

[0039] Embodiment 1:

[0040] A two-step method for achieving hydrophobicity and oleophobicity of aerogels comprises the following steps:

[0041] (1) Prepare a piece of complete structure with dimensions of 150 mm × 150 mm × 20 mm and a density of 0.25 g / cm 3 Alumina aerogel material.

[0042] (2) The alumina aerogel material in (1) is placed in a sealed container containing 5 g of perfluoro modifier 1H,1H,2H,2H-perfluorooctyltrimethoxysilane. Figure 1 The figure is a schematic diagram of a hydrophobic and oleophobic gas phase treatment container, which is provided with a pressure gauge, valve A, and valve B. A screen is provided inside the container, and aerogel is placed on the screen. A perfluorinated modifier is placed below the screen and at the bottom of the container. The screen separates the aerogel from the perfluorinated modifier, and the screen is a porous structure. The gas phase perfluorinated modifier can pass through the screen into the upper part and contact with the aerogel for gas phase treatment.

[0043] (3) Close valve A and valve B, evacuate the container in (2) to below 50 Pa, and place it in a 90°C oven and heat for 12 hours to vaporize the perfluorinated modifier.

[0044] (4) With the help of negative pressure, 2 g of pure water is sucked into the container in (3) through valve A and continued to heat in a 90°C oven for 12 h.

[0045] (5) After the container in (4) is taken out of the oven and cooled to room temperature, the alumina aerogel material is taken out.

[0046] (6) Add 50 g of the perfluoro modifier 1H,1H,2H,2H-perfluorooctyltrimethoxysilane to 1000 mL of a mixed solvent of ethanol / water (volume ratio 4 / 1), stir and mix well, then add 0.5 g of glacial acetic acid to the solution, stir and mix well, to obtain a perfluoro modifier solution.

[0047] (7) Soak the alumina aerogel material obtained in (5) into the solution in (6), slowly stir, and soak for 24 hours.

[0048] (8) The alumina aerogel material in (7) is taken out from the solution, left to air, and heated to dry until the weight does not change, thereby finally obtaining a hydrophobic and oleophobic alumina aerogel material.

[0049] Finally, the alumina aerogel material obtained after hydrophobic and oleophobic treatment gained 10.5% in weight, and the static contact angle of water was 150°, and the static contact angle of silicone oil was 130°.

[0050] Figure 2 This is a scanning electron microscope image of the alumina aerogel material after the hydrophobic and oleophobic treatment. It can be seen that the hydrophobic and oleophobic treatment did not destroy the pore structure of the aerogel.

[0051] Figure 3 This is a display of the alumina aerogel material after the hydrophobic and oleophobic treatment. It can be seen that the alumina aerogel material has a good repelling effect on water and silicone oil, indicating that the hydrophobic and oleophobic modification is effective.

[0052] Embodiment 2:

[0053] A two-step method for achieving hydrophobicity and oleophobicity of aerogels comprises the following steps:

[0054] (1) Prepare a piece of complete structure with dimensions of 150 mm × 150 mm × 20 mm and a density of 0.45 g / cm 3 Phenolic aerogel material.

[0055] (2) The phenolic aerogel material in (1) is placed in a sealed container containing 10 g of a perfluorinated modifier 1H,1H,2H,2H-perfluorodecyltriethoxysilane.

[0056] (3) Evacuate the container in (2) to below 50 Pa and heat it in a 120°C oven for 12 h.

[0057] (4) With the help of negative pressure, 4 g of pure water is sucked into the container in (3) through valve A and continued to heat in a 120°C oven for 12 h.

[0058] (5) After the container in (4) is taken out of the oven and cooled to room temperature, the phenolic aerogel material is taken out.

[0059] (6) Add 70 g of the perfluoro modifier 1H,1H,2H,2H-perfluorodecyltriethoxysilane to 1000 mL of a mixed solvent of ethanol / water (volume ratio 4 / 1), stir and mix well, then add 1 g of benzoic acid to the solution, stir and mix well, to obtain a perfluoro modifier solution.

[0060] (7) Soak the phenolic aerogel material obtained in (5) into the solution in (6), slowly stir, and soak for 24 hours.

[0061] (8) The phenolic aerogel material in (7) is taken out from the solution, left to air, and heated to dry until the weight does not change, thereby finally obtaining a hydrophobic and oleophobic phenolic aerogel material.

[0062] Finally, the phenolic aerogel material obtained after hydrophobic and oleophobic treatment gained 18.5% in weight, the static contact angle of water was 148°, and the static contact angle of silicone oil was 120°.

[0063] Embodiment 3:

[0064] A two-step method for achieving hydrophobicity and oleophobicity of aerogels comprises the following steps:

[0065] (1) Prepare a piece of complete structure with dimensions of 150 mm × 150 mm × 20 mm and a density of 0.15 g / cm 3 Silica aerogel material.

[0066] (2) The silica aerogel material in (1) is placed in a sealed container containing 5 g of a perfluoro modifier, 1H,1H,2H,2H-perfluorooctyltriethoxysilane.

[0067] (3) Evacuate the container in (2) to below 50 Pa and heat it in a 90°C oven for 12 h.

[0068] (4) With the help of negative pressure, 2 g of pure water is sucked into the container in (3) through valve A and continued to heat in a 90°C oven for 12 h.

[0069] (5) The container in (4) is taken out of the oven and cooled to room temperature, and then the silica aerogel material is taken out.

[0070] (6) 30 g of the perfluoro modifier 1H,1H,2H,2H-perfluorooctyltriethoxysilane was added to 1000 mL of a mixed solvent of ethanol / water (volume ratio 4 / 1), and 0.2 g of oxalic acid was added to the solution after stirring and mixing evenly, and the mixture was stirred and mixed evenly to obtain a perfluoro modifier solution.

[0071] (7) Soak the silica aerogel material obtained in (5) into the solution in (6), slowly stir, and soak for 24 hours.

[0072] (8) The silica aerogel material in (7) is taken out from the solution, left to air-dry, and heated to dry until the weight does not change, thereby finally obtaining a hydrophobic and oleophobic phenolic aerogel material.

[0073] Finally, the silica aerogel material obtained after hydrophobic and oleophobic treatment gained 15% in weight, and the static contact angle of water was 150°, and the static contact angle of silicone oil was 125°.

[0074] The specific embodiments of the present invention disclosed above are intended to help understand the content of the present invention and implement it accordingly. It can be understood by those skilled in the art that various replacements, changes and modifications are possible without departing from the spirit and scope of the present invention. The present invention should not be limited to the contents disclosed in the embodiments of this specification, and the scope of protection of the present invention shall be subject to the scope defined in the claims.

Claims

1. A two-step method for achieving hydrophobicity and oleophobicity of aerogel materials, characterized in that: The following steps are involved: The aerogel is modified by gas phase treatment using a perfluorinated modifier to form a hydrophobic and oleophobic layer on the surface of the aerogel; The aerogel after gas phase treatment is subjected to liquid phase treatment by using a perfluorinated modifier solution to form a hydrophobic and oleophobic layer densely covering the aerogel.

2. The method according to claim 1, characterized in that The method of modifying the aerogel by gas phase treatment using a perfluorinated modifier comprises: (1) preparing an aerogel material to be treated with hydrophobic and oleophobic treatment; (2) placing the aerogel material in a sealed container containing a perfluorinated modifier; (3) evacuating the sealed container and heating it in an oven; (4) Pour pure water into the sealed container and continue heating; (5) After the sealed container is taken out of the oven and cooled to room temperature, the aerogel material is taken out.

3. The method according to claim 2, characterized in that A screen is arranged inside the sealed container, aerogel is placed on the screen, and a perfluorinated modifier is placed below the screen and at the bottom of the container.

4. The method according to claim 2, characterized in that: The method of using a perfluorinated modifier solution to liquid-phase treat the aerogel after gas-phase treatment comprises: (6) preparing a perfluorinated modifier solution; (7) soaking the aerogel material obtained in step (5) in a perfluorinated modifier solution; (8) The aerogel material is taken out from the perfluorinated modifier solution, left to air-dry, and heated to dry until the weight does not change, thereby finally obtaining a hydrophobic and oleophobic aerogel material.

5. The method according to claim 4, characterized in that The acid catalyst used in preparing the perfluorinated modifier solution is one or more of glacial acetic acid, oxalic acid, and benzoic acid.

6. The method according to claim 1, characterized in that The perfluorinated modifier is one or more of 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorooctyltrimethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane, and 1H,1H,2H,2H-perfluorodecyltrimethoxysilane.

7. The method according to claim 1, characterized in that The mass of the perfluorinated modifier used in the gas phase treatment is 1% to 10% of the mass of the aerogel; the mass of the perfluorinated modifier used in the liquid phase treatment is 10% to 50% of the mass of the aerogel.

8. The method according to claim 1, characterized in that The temperature range of the gas phase treatment is 90°C to 150°C.

9. The method according to claim 1, characterized in that: The mass of the pure water used in the gas phase treatment is 10% to 50% of the mass of the perfluorinated modifier.

10. A hydrophobic and oleophobic aerogel material prepared according to the method according to any one of claims 1 to 9.

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