Super-hydrophobic carbon-doped ceramic aerogel material and preparation method thereof

Abstract

The invention discloses a super-hydrophobic carbon-doped ceramic aerogel material and a preparation method thereof, and belongs to the technical field of aerogel, and the preparation method of the super-hydrophobic carbon-doped ceramic aerogel material comprises the following steps: uniformly dispersing hydrophobic hexagonal boron nitride nanoparticles, epoxy resin, a curing agent and a diluent to prepare a hydrophobic coating; spraying hydrophobic paint on the surface of the rough S C ceramic aerogel by using a spray gun, and curing at room temperature to obtain super-hydrophobic carbon-doped ceramic aerogel; graphite carbon is adopted to support a carbon aerogel skeleton, the roughness of the surface of the aerogel is increased through acid etching, the binding force between the aerogel and epoxy resin is enhanced, the epoxy resin generates strong cohesive force and adhesive force in the curing process so that the ceramic aerogel and hydrophobic particles can be tightly connected together, and the hydrophobic particles are tightly bonded together. The obtained aerogel has high strength and super-hydrophobicity, and has a good application prospect in a humid and hot environment.

Description

Technical Field

[0001] The invention belongs to the technical field of aerogels, and in particular relates to a super-hydrophobic carbon-doped ceramic aerogel material and a preparation method thereof. Background Art

[0002] Due to the fine nano-network structure of aerogel, its structure will collapse and pulverize when it comes into contact with water without hydrophobic treatment, resulting in the loss of many properties (such as high specific surface area, high porosity or low density, etc.). The existing technology for hydrophobic modification in the aerogel preparation process is to add silicone, but it is still difficult to obtain super hydrophobic aerogel with good performance.

[0003] Silicon carbide (SiC) aerogel has the advantages of light texture and good thermal stability. However, the currently reported SiC aerogels generally have poor mechanical properties and a large number of hydrophilic functional groups (such as hydroxyl groups) on the surface, which greatly limits the application of SiC aerogel in humid environments. Summary of the invention

[0004] In order to solve the technical problems of poor mechanical properties and poor hydrophobicity of silicon carbide aerogel mentioned in the background technology, the present invention provides a super-hydrophobic carbon-doped ceramic aerogel material and a preparation method thereof.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A method for preparing a super-hydrophobic carbon-doped ceramic aerogel comprises the following steps:

[0007] The first step is to ultrasonically disperse the hexagonal boron nitride nanoparticles in anhydrous ethanol for 2 hours, then add hydrochloric acid solution and long-chain alkyl chlorosilane, heat to 70°C, stir for 1-2 hours, ultrasonicate for 1-2 hours, filter, dry for 36-48 hours, and grind to obtain hydrophobic hexagonal boron nitride nanoparticles;

[0008] The second step is to ultrasonically clean the SiC ceramic aerogel in anhydrous ethanol and deionized water for 3 hours, dry it for 5 hours, and then etch it in an acid solution for 48-96 hours. After the etching is completed, ultrasonically clean it in deionized water for 15 minutes and then dry it at 60°C for 5 hours to obtain a SiC ceramic aerogel with a rough surface.

[0009] The third step is to evenly mix the hydrophobic hexagonal boron nitride nanoparticles, diluent, epoxy resin, and amine curing agent, and disperse them in a homogenizer at a speed of 20,000 r / min for 10 minutes to obtain a hydrophobic coating. The hydrophobic coating is sprayed on the rough surface of the Si C ceramic aerogel with a spray gun and cured at room temperature for 12 hours to obtain the Si C ceramic aerogel wrapped with a hydrophobic coating.

[0010] Furthermore, the usage ratio of the hexagonal boron nitride nanoparticles, anhydrous ethanol, hydrochloric acid solution and long-chain alkyl chlorosilane is 3-5 g: 9-15 g: 0.15-0.3 mL: 0.3-0.5 mL, and the concentration of the hydrochloric acid solution is 1 wt.%.

[0011] Furthermore, the long-chain alkyl chlorosilane is any one or more of octadecyltrichlorosilane, hexadecyltrichlorosilane, and octyltrichlorosilane.

[0012] Furthermore, the method for preparing the super-hydrophobic carbon-doped ceramic aerogel is characterized in that the preparation of the SiC ceramic aerogel comprises the following steps:

[0013] Peel the eggplant and cut it into pieces with a length of 2 cm, a width of 2 cm and a height of 1 cm. Freeze it at -84°C for 6-8 hours, then dry it in a freeze dryer for 24-48 hours, then move it to a tubular furnace, heat it to 800°C under an argon atmosphere, keep it warm for 2 hours and then cool it to room temperature to obtain carbon aerogel. Mix graphite powder and silicon monoxide powder and spread it on the bottom of a porcelain boat, then spread a layer of carbon aerogel, then put the porcelain boat into a tubular furnace, heat it to 1400°C under an argon atmosphere, keep it warm for 2 hours and then cool it to room temperature to obtain SiC ceramic aerogel.

[0014] Furthermore, the mass ratio of carbon aerogel, graphite powder and silicon monoxide is 1:1:14.6.

[0015] Furthermore, the usage ratio of the SiC ceramic aerogel to anhydrous ethanol, deionized water and acid solution is 0.1g:10ml:10ml:10-20ml.

[0016] Furthermore, the acid solution is any one or more of a sulfuric acid solution, an oxalic acid solution, and a nitric acid solution, and the concentration is 1-2 wt.%.

[0017] Furthermore, the epoxy resin is any one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and novolac epoxy resin.

[0018] Furthermore, the curing agent is any one or more of ethylenediamine, diethylenetriamine, and triethylenetetramine.

[0019] Furthermore, the diluent is any one or more of acetone, toluene and xylene.

[0020] Furthermore, the mass ratio of the hydrophobic hexagonal boron nitride nanoparticles, epoxy resin, curing agent and diluent is 5-10:5-10:2-4:50-100.

[0021] Furthermore, the spraying thickness is 0.1-0.2 mm.

[0022] Furthermore, the process parameters of the spraying are as follows: spraying distance 5 cm, spraying pressure 0.5 MPa, spraying flow rate 2 mL / min, and the spraying angle is perpendicular to the spraying surface.

[0023] Furthermore, a super-hydrophobic carbon-doped ceramic aerogel is prepared by the above preparation method.

[0024] Beneficial effects of the present invention:

[0025] The invention adopts a sacrificial template method, uses carbon aerogel as a carbon source and silicon monoxide as a silicon source to prepare SiC ceramic aerogel, and graphite carbon is used as a reinforcing phase to support the skeleton of the carbon aerogel and improve the strength of the material; the SiC ceramic aerogel is acid-etched to roughen its surface, thereby enhancing the bonding force between the epoxy resin and the SiC ceramic aerogel; the epoxy resin serves as a "bridge" to generate a cross-linked polymer during the curing process, thereby generating strong cohesive force and adhesive force to tightly connect the ceramic aerogel and the hydrophobic hexagonal boron nitride nanoparticles together; the stable layered structure of the hexagonal boron nitride and the non-polar characteristics of the NB bond make the interaction between the surface of the hexagonal boron nitride weak and have hydrophobicity; when the hydroxyl groups on the surface of the hexagonal boron nitride are replaced by long-chain alkyl groups, the steric hindrance between the molecules is increased, making it difficult for the long-chain alkyl molecules to be closely arranged in an aqueous solution, thereby reducing the interaction between them and the water molecules, and further enhancing the hydrophobicity; in addition, the hexagonal boron nitride nanoparticles can generate a larger contact area with the epoxy resin matrix, form a stronger interface bonding force, and further improve the overall strength of the aerogel. DETAILED DESCRIPTION

[0026] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0027] Example 1

[0028] A method for preparing a super-hydrophobic carbon-doped ceramic aerogel comprises the following steps:

[0029] Step 1: 3 g of hexagonal boron nitride nanoparticles were ultrasonically dispersed in 9 g of anhydrous ethanol for 2 h, and then 0.15 mL of 1 wt.% hydrochloric acid solution and 0.3 mL of octadecyltrichlorosilane were added, the temperature was raised to 70°C, stirred for 1 h, ultrasonicated for 1 h, filtered, dried for 36 h, and then ground to obtain hydrophobic hexagonal boron nitride nanoparticles;

[0030] Step 2: 0.12 g of Si C ceramic aerogel was ultrasonically cleaned in 12 mL of anhydrous ethanol and 12 mL of deionized water for 3 h, dried for 5 h, and then etched in 12 mL of 1 wt.% sulfuric acid solution for 48 h. After etching, it was ultrasonically cleaned in 60 mL of deionized water for 15 min and dried at 60°C for 5 h to obtain Si C ceramic aerogel with a rough surface.

[0031] The third step is to mix 5g of hydrophobic hexagonal boron nitride nanoparticles, 5g of bisphenol A epoxy resin, 2g of ethylenediamine and 50g of acetone evenly, and disperse them in a homogenizer at a speed of 20000r / min for 10min to obtain a hydrophobic coating. The hydrophobic coating is sprayed on the rough SiC ceramic aerogel surface 0.1mm with a spray gun, and cured at room temperature for 12h to obtain SiC ceramic aerogel wrapped with a hydrophobic coating. The spraying process parameters are as follows: spraying distance 5cm, spraying pressure 0.5MPa, spraying flow rate 2mL / min, and the spraying angle is perpendicular to the spraying surface.

[0032] SiC ceramic aerogel is made by the following steps:

[0033] The eggplant was peeled and cut into pieces with a length of 2 cm, a width of 2 cm and a height of 1 cm. The pieces were frozen at -84°C for 6 h and then dried in a freeze dryer for 12 h. The pieces were then transferred to a tubular furnace and heated to 800°C under an argon atmosphere. The mixture was kept warm for 2 h and then cooled to room temperature to obtain 0.12 g of carbon aerogel. 0.12 g of graphite powder and 1.76 g of silicon monoxide powder were mixed and spread on the bottom of a porcelain boat. A layer of carbon aerogel was then placed on the porcelain boat. The porcelain boat was then placed in a tubular furnace and heated to 1400°C under an argon atmosphere. The mixture was kept warm for 2 h and then cooled to room temperature to obtain SiC ceramic aerogel.

[0034] Example 2

[0035] A method for preparing a super-hydrophobic carbon-doped ceramic aerogel comprises the following steps:

[0036] Step 1: 4 g of hexagonal boron nitride nanoparticles were ultrasonically dispersed in 12 g of anhydrous ethanol for 2 h, and then 0.2 mL of 1 wt.% hydrochloric acid solution and 0.4 mL of hexadecyltrichlorosilane were added, the temperature was raised to 70°C, stirred for 1.5 h, ultrasonicated for 1.5 h, filtered, dried for 42 h, and then ground to obtain hydrophobic hexagonal boron nitride nanoparticles;

[0037] Step 2: 0.12 g of Si C ceramic aerogel was ultrasonically cleaned in 12 mL of anhydrous ethanol and 12 mL of deionized water for 3 h, dried for 5 h, and then etched in 18 mL of 1.5 wt.% oxalic acid solution for 72 h. After etching, it was ultrasonically cleaned in 60 mL of deionized water for 15 min and dried at 60 ° C for 5 h to obtain Si C ceramic aerogel with a rough surface.

[0038] The third step is to mix 8g of hydrophobic hexagonal boron nitride nanoparticles, 8g of bisphenol F epoxy resin, 3g of diethylenetriamine and 75g of toluene, and then disperse them in a homogenizer at a speed of 20000r / min for 10min to obtain a hydrophobic coating. Use a spray gun to spray the super hydrophobic coating on the rough surface of SiC ceramic aerogel with a diameter of 0.15mm, and cure it at room temperature for 12h to obtain SiC ceramic aerogel wrapped with a hydrophobic coating. The spraying process parameters are as follows: spraying distance 5cm, spraying pressure 0.5MPa, spraying flow rate 2mL / min, and the spraying angle is perpendicular to the spraying surface.

[0039] The preparation process of SiC ceramic aerogel is the same as that in Example 1.

[0040] Example 3

[0041] A method for preparing a super-hydrophobic carbon-doped ceramic aerogel comprises the following steps:

[0042] Step 1: ultrasonically disperse 5 g of hexagonal boron nitride nanoparticles in 15 g of anhydrous ethanol for 2 h, then add 0.3 mL of 1 wt.% hydrochloric acid solution and 0.5 mL of octyltrichlorosilane, heat to 70°C, stir for 2 h, ultrasonicate for 2 h, filter, dry for 48 h, and grind to obtain hydrophobically modified hexagonal boron nitride nanoparticles;

[0043] Step 2: 0.12 g of Si C ceramic aerogel was ultrasonically cleaned in 12 mL of anhydrous ethanol and 12 mL of deionized water for 3 h, dried for 5 h, and then etched in 24 mL of 2 wt.% nitric acid solution for 96 h. After etching, it was ultrasonically cleaned in 60 mL of deionized water for 15 min and dried at 60° C. for 5 h to obtain Si C ceramic aerogel with a rough surface.

[0044] The third step is to mix 10g of hydrophobic hexagonal boron nitride nanoparticles, 10g of phenolic epoxy resin, 4g of triethylenetetramine and 100g of xylene evenly, and disperse them in a homogenizer at a speed of 20000r / min for 10min to obtain a hydrophobic coating. The hydrophobic coating is sprayed on the rough surface of the SiC ceramic aerogel by a spray gun at 0.2mm, and cured at room temperature for 12h to obtain the SiC ceramic aerogel wrapped with a hydrophobic coating. The spraying process parameters are as follows: spraying distance 5cm, spraying pressure 0.5MPa, spraying flow rate 2mL / min, and the spraying angle is perpendicular to the spraying surface.

[0045] The preparation process of SiC ceramic aerogel is the same as that in Example 1.

[0046] Example 4

[0047] The etching time in Example 1 was extended from "48h" to "96h", and the remaining raw materials and preparation process were the same as in Example 1.

[0048] Comparative Example 1

[0049] The "graphite powder" in the preparation process of SiC ceramic aerogel in Example 1 was removed, and the amount of silicon monoxide was replaced from "1.76g" to "0.88g". The remaining raw materials and preparation process were the same as in Example 1.

[0050] Comparative Example 2

[0051] The first step in Example 2 is removed, and the "hydrophobic hexagonal boron nitride nanoparticles" in the third step are replaced by "hexagonal boron nitride nanoparticles". The remaining raw materials and preparation process are the same as in Example 2.

[0052] The SiC ceramic aerogels wrapped with the hydrophobic coating obtained in Examples 1 to 4 and Comparative Examples 1 to 2 were subjected to performance tests, wherein the compressive strength test was conducted in accordance with the test standard GB / T13480-2014 "Determination of compressive properties of thermal insulation products for building use", and the hydrophobicity was measured using a YI KE-360A contact angle meter. The test results are shown in Table 1:

[0053] Table 1

[0054]

[0055]

[0056] As can be seen from Table 1, the coating thickness of the hydrophobic coating on the surface of the aerogel is relatively thin, and the pore structure inside the aerogel will not be significantly affected, so the aerogel porosity remains substantially unchanged; Comparative Example 1 and Comparative Example 1 show that when the carbon aerogel skeleton is not doped with graphite carbon, its compressive strength at 10% compression is only 0.55Mpa, indicating that carbon doping improves the strength of the material; Comparative Example 1 and Example 4 show that when the acid etching time is extended, the surface roughness of the aerogel becomes larger, which is more conducive to the attachment of the film layer, and the material strength and hydrophobicity are increased; Comparative Example 2 and Comparative Example 2 show that when the surface of the hexagonal boron nitride nanoparticles is hydrophobically modified with hexadecyltrichlorosilane, the contact angle with water is increased from 138° to 162°, and super-hydrophobic performance is obtained. In summary, the super-hydrophobic coating prepared by the present invention is coated with carbon-doped Si C ceramic aerogel with high strength and super-hydrophobicity, and has good application prospects in hot and humid environments.

[0057] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing superhydrophobic carbon-doped ceramic aerogel, characterized in that: The following steps are involved: The first step is to ultrasonically disperse the hexagonal boron nitride nanoparticles in anhydrous ethanol, add a hydrochloric acid solution and a long-chain alkyl chlorosilane, stir, ultrasonicate, filter, dry, and grind to obtain hydrophobic hexagonal boron nitride nanoparticles; The second step is to wash the SiC ceramic aerogel in anhydrous ethanol and deionized water, respectively, and then dry it and then etch it in an acid solution. After the etching is completed, wash it and dry it to obtain a SiC ceramic aerogel with a rough surface. The third step is to stir and disperse the hydrophobic hexagonal boron nitride nanoparticles, diluent, epoxy resin and amine curing agent to prepare a hydrophobic coating, spray the hydrophobic coating on the rough surface of SiC ceramic aerogel with a spray gun, and cure it at room temperature to obtain SiC ceramic aerogel wrapped with a hydrophobic coating.

2. The method for preparing a super-hydrophobic carbon-doped ceramic aerogel according to claim 1, characterized in that: The dosage ratio of hexagonal boron nitride nanoparticles, anhydrous ethanol, hydrochloric acid solution and long-chain alkyl chlorosilane is 3-5g:9-15g:0.15-0.3mL:0.3-0.5mL, and the concentration of the hydrochloric acid solution is 1wt.%.

3. The method for preparing a super-hydrophobic carbon-doped ceramic aerogel according to claim 1, characterized in that: The long-chain alkyl chlorosilane is any one or more of octadecyltrichlorosilane, hexadecyltrichlorosilane and octyltrichlorosilane.

4. The method for preparing a super-hydrophobic carbon-doped ceramic aerogel according to claim 1, characterized in that: The dosage ratio of SiC ceramic aerogel, anhydrous ethanol, deionized water and acid solution is 1g:10ml:10ml:10-20ml.

5. The method for preparing a super-hydrophobic carbon-doped ceramic aerogel according to claim 1, characterized in that: The acid solution is any one or more of a sulfuric acid solution, an oxalic acid solution, and a nitric acid solution, and the concentration is 1-2 wt.%.

6. The method for preparing a super-hydrophobic carbon-doped ceramic aerogel according to claim 1, characterized in that: The preparation of SiC ceramic aerogel includes the following steps: The eggplant was peeled and cut into pieces with a length of 2 cm, a width of 2 cm and a height of 1 cm. The pieces were frozen at -84°C for 6-8 hours and then dried in a freeze dryer for 24-48 hours. The pieces were then transferred to a tubular furnace and heated to 800°C under an argon atmosphere. The mixture was kept warm for 2 hours and then cooled to room temperature to obtain carbon aerogel. Graphite powder and silicon monoxide powder were mixed and spread on the bottom of a porcelain boat. A layer of carbon aerogel was then placed on the porcelain boat. The porcelain boat was then placed in a tubular furnace and heated to 1400°C under an argon atmosphere. The mixture was kept warm for 2 hours and then cooled to room temperature to obtain SiC ceramic aerogel.

7. The method for preparing a super-hydrophobic carbon-doped ceramic aerogel according to claim 6, characterized in that: The mass ratio of carbon aerogel, graphite powder and silicon monoxide is 1:1:14.

6.

8. The method for preparing a super-hydrophobic carbon-doped ceramic aerogel according to claim 1, characterized in that: The mass ratio of the hydrophobic hexagonal boron nitride nanoparticles, the epoxy resin, the curing agent and the diluent is 5-10:5-10:2-4:50-100, and the spraying thickness is 0.1-0.2 mm.

9. The method for preparing a super-hydrophobic carbon-doped ceramic aerogel according to claim 1, characterized in that: The epoxy resin is any one or more of bisphenol A epoxy resin, bisphenol F epoxy resin, and phenolic epoxy resin; the curing agent is any one or more of ethylenediamine, diethylenetriamine, and triethylenetetramine; and the diluent is any one or more of acetone, toluene, and xylene.

10. A superhydrophobic carbon-doped ceramic aerogel, characterized in that: Prepared by the preparation method according to any one of claims 1 to 9.

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