CN117303380A - Super-hydrophobic silicon oxide aerogel material and preparation method thereof - Google Patents
Super-hydrophobic silicon oxide aerogel material and preparation method thereof Download PDFInfo
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 76
- 239000000463 material Substances 0.000 title claims abstract description 42
- 230000003075 superhydrophobic effect Effects 0.000 title claims abstract description 33
- 238000002360 preparation method Methods 0.000 title claims abstract description 15
- 239000004964 aerogel Substances 0.000 title abstract description 13
- 229910052814 silicon oxide Inorganic materials 0.000 title description 4
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 110
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 69
- 238000006243 chemical reaction Methods 0.000 claims abstract description 55
- 239000004965 Silica aerogel Substances 0.000 claims abstract description 34
- IJOOHPMOJXWVHK-UHFFFAOYSA-N chlorotrimethylsilane Chemical compound C[Si](C)(C)Cl IJOOHPMOJXWVHK-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000005046 Chlorosilane Substances 0.000 claims abstract description 30
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical compound Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 claims abstract description 30
- VXEGSRKPIUDPQT-UHFFFAOYSA-N 4-[4-(4-methoxyphenyl)piperazin-1-yl]aniline Chemical compound C1=CC(OC)=CC=C1N1CCN(C=2C=CC(N)=CC=2)CC1 VXEGSRKPIUDPQT-UHFFFAOYSA-N 0.000 claims abstract description 22
- 238000000034 method Methods 0.000 claims abstract description 22
- 239000005049 silicon tetrachloride Substances 0.000 claims abstract description 22
- 239000005051 trimethylchlorosilane Substances 0.000 claims abstract description 17
- 230000002209 hydrophobic effect Effects 0.000 claims abstract description 16
- 239000002904 solvent Substances 0.000 claims abstract description 9
- 239000000243 solution Substances 0.000 claims description 62
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 32
- 239000000499 gel Substances 0.000 claims description 29
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 21
- 239000003513 alkali Substances 0.000 claims description 21
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims description 21
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims description 21
- 239000000377 silicon dioxide Substances 0.000 claims description 19
- 238000001879 gelation Methods 0.000 claims description 16
- 239000011240 wet gel Substances 0.000 claims description 16
- 238000007599 discharging Methods 0.000 claims description 15
- 238000001035 drying Methods 0.000 claims description 14
- 239000007789 gas Substances 0.000 claims description 14
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 12
- 238000005406 washing Methods 0.000 claims description 10
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 9
- 239000000203 mixture Substances 0.000 claims description 4
- 239000002657 fibrous material Substances 0.000 claims description 3
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 3
- 239000011259 mixed solution Substances 0.000 claims description 3
- 238000005470 impregnation Methods 0.000 claims description 2
- 238000003756 stirring Methods 0.000 claims description 2
- 238000006460 hydrolysis reaction Methods 0.000 abstract description 11
- 230000007062 hydrolysis Effects 0.000 abstract description 10
- 230000008569 process Effects 0.000 abstract description 7
- 238000009413 insulation Methods 0.000 abstract description 6
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- 239000002994 raw material Substances 0.000 abstract description 4
- 239000003607 modifier Substances 0.000 abstract description 2
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 18
- IDGUHHHQCWSQLU-UHFFFAOYSA-N ethanol;hydrate Chemical compound O.CCO IDGUHHHQCWSQLU-UHFFFAOYSA-N 0.000 description 10
- 238000004821 distillation Methods 0.000 description 8
- 238000010992 reflux Methods 0.000 description 8
- 238000010438 heat treatment Methods 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 5
- 239000000835 fiber Substances 0.000 description 5
- 239000000843 powder Substances 0.000 description 5
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical group CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 3
- YGZSVWMBUCGDCV-UHFFFAOYSA-N chloro(methyl)silane Chemical compound C[SiH2]Cl YGZSVWMBUCGDCV-UHFFFAOYSA-N 0.000 description 3
- 239000003365 glass fiber Substances 0.000 description 3
- 229920002748 Basalt fiber Polymers 0.000 description 2
- 229920000049 Carbon (fiber) Polymers 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical group O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000006136 alcoholysis reaction Methods 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 239000004917 carbon fiber Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 238000004064 recycling Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000010703 silicon Substances 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 238000002791 soaking Methods 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 238000001694 spray drying Methods 0.000 description 2
- 238000000352 supercritical drying Methods 0.000 description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- 239000006087 Silane Coupling Agent Substances 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 150000004703 alkoxides Chemical class 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- 229920006231 aramid fiber Polymers 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000004108 freeze drying Methods 0.000 description 1
- UQEAIHBTYFGYIE-UHFFFAOYSA-N hexamethyldisiloxane Chemical compound C[Si](C)(C)O[Si](C)(C)C UQEAIHBTYFGYIE-UHFFFAOYSA-N 0.000 description 1
- JYVHOGDBFNJNMR-UHFFFAOYSA-N hexane;hydrate Chemical compound O.CCCCCC JYVHOGDBFNJNMR-UHFFFAOYSA-N 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 150000001282 organosilanes Chemical class 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 239000000047 product Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000000565 sealant Substances 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000000741 silica gel Substances 0.000 description 1
- 229910002027 silica gel Inorganic materials 0.000 description 1
- XJKVPKYVPCWHFO-UHFFFAOYSA-N silicon;hydrate Chemical compound O.[Si] XJKVPKYVPCWHFO-UHFFFAOYSA-N 0.000 description 1
- 229920002050 silicone resin Polymers 0.000 description 1
- 229920002379 silicone rubber Polymers 0.000 description 1
- 239000004945 silicone rubber Substances 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
- C01B33/157—After-treatment of gels
- C01B33/158—Purification; Drying; Dehydrating
- C01B33/1585—Dehydration into aerogels
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
- C01B33/155—Preparation of hydroorganogels or organogels
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B33/00—Silicon; Compounds thereof
- C01B33/113—Silicon oxides; Hydrates thereof
- C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
- C01B33/14—Colloidal silica, e.g. dispersions, gels, sols
- C01B33/157—After-treatment of gels
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/32—Thermal properties
Landscapes
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Silicon Compounds (AREA)
Abstract
The invention relates to the technical field of aerogel material production, in particular to a super-hydrophobic silica aerogel material and a preparation method thereof. The method provided by the invention is to prepare the super-hydrophobic silica aerogel by taking the chlorosilane azeotrope as a raw material, and by controlling the reaction temperature, introducing water in multiple steps under the action of an alcohol solvent, and the like, the problems that gel is difficult to form and difficult to hydrophobically modify due to different hydrolysis rates of silicon tetrachloride and trimethylchlorosilane in the process of preparing the silica aerogel, and the preparation process is complex and the preparation cost is high due to the need of adding a hydrophobic modifier in the process of preparing the aerogel are solved, and the finally prepared super-hydrophobic silica aerogel material has excellent heat insulation performance and super-hydrophobic characteristics. The preparation method provided by the invention is simple, has lower preparation cost, realizes the resource utilization of the chlorosilane azeotrope, and also endows the chlorosilane azeotrope with higher economic value.
Description
Technical Field
The invention relates to the technical field of aerogel material production, in particular to a super-hydrophobic silica aerogel material and a preparation method thereof.
Background
Silicon dioxide (SiO) 2 ) The aerogel is a porous material, has excellent performances of heat insulation, heat preservation, sound insulation, noise reduction, shock absorption, energy absorption, selective adsorption and the like, and has wide application potential in the fields of mechanics, optics, acoustics, electrician electronics, thermal engineering, aerospace, construction, adsorption separation and the like. At present, silica aerogel is prepared by preparing silica sol through catalytic hydrolysis of a silicon source, and preparing aerogel through steps of gel, aging, drying and the like.
In recent years, the productivity of the organosilicon industry is continuously developed, the preparation process of organosilane production enterprises is gradually mature, the productivity is continuously improved, and the amount of industrial byproducts is continuously increased. Methyl chlorosilane is a main monomer for synthesizing an organosilicon high polymer, is used for manufacturing silicone resin and silicone rubber, preparing an organosilicon adhesive and a sealant, is also used for producing a silane coupling agent, and has wider application. But industrial by-product chlorosilane azeotropes are produced during the production of methylchlorosilanes. The main components in the chlorosilane azeotrope are trimethylchlorosilane and silicon tetrachloride, and the trimethylchlorosilane and the silicon tetrachloride can react with water to generate hydrogen chloride, so that the chlorosilane azeotrope has strong corrosiveness and strong pollution and has high treatment cost. The resource utilization of the chlorosilane azeotrope is changed into valuable, and the method is a better way for treating the chlorosilane azeotrope.
Studies have shown that both trimethylchlorosilane and silicon tetrachloride in chlorosilane azeotropes are sources of silicon for producing silica aerogels. For example, the Chinese patent application CN115010140A uses trimethylchlorosilane, alcohol and other components to prepare the super-hydrophobic aerogel through the processes of hydrolysis, gel, drying and the like; chinese patent application CN101863480 a uses silicon tetrachloride and water as raw materials, and prepares silica aerogel by steps of hydrolysis, gelation, drying, and the like. Thus, the preparation of silica aerogel using chlorosilane azeotrope may be a better way to realize the recycling of chlorosilane azeotrope, and has better prospect. However, because the hydrolysis rate difference between silicon tetrachloride and trimethylchlorosilane is large, the direct use of chlorosilane azeotrope and alcohol can lead to difficult or impossible formation of gel, and white powder or flocculent precipitate can be directly generated; and even if gel formation is possible, the final aerogel product produced is not well hydrophobized.
Disclosure of Invention
In order to solve the technical problems, the invention provides a method for preparing a silicon oxide aerogel material by utilizing chlorosilane azeotrope through controlling the reaction temperature, introducing water in multiple steps and the like, and obtaining the super-hydrophobic silicon oxide aerogel material. The specific technical scheme is as follows:
in a first aspect of the present invention, there is provided a method for preparing a superhydrophobic silica aerogel material, comprising the steps of:
step 1, dropwise adding a chlorosilane azeotrope into an alcohol-water solution, reacting at 10 ℃, continuously discharging generated hydrogen chloride in the reaction process, and separating ethanol and hydrogen chloride after the reaction to obtain a reaction solution;
step 2, dropwise adding an alcohol water solution into the reaction solution again, reacting at the temperature of 10 ℃, and continuously discharging generated hydrogen chloride gas in the reaction process to obtain hydrophobic silica sol;
step 3, adding an alcohol alkali solution into the silica sol, uniformly stirring, standing for gel, and washing after gel to obtain a silica wet gel material;
and step 4, drying to obtain the super-hydrophobic silica aerogel material.
Preferably, the alcohol-water solution in the step 1 and the step 2 is a mixed solution of alcohol and water, wherein the alcohol is selected from one of ethanol, methanol and ethylene glycol, and the water is pure water or deionized water;
preferably, the temperature of the alcohol water solution in the step 1 and the step 2 is 0-10 ℃, and the alcohol water solution is controlled at a lower temperature to ensure that the reaction in the step 1 is carried out at a lower temperature, so that the reaction rate can be controlled, and sol formation and sol hydrophobization are more facilitated;
preferably, in the step 1, the content of trimethylchlorosilane in the chlorosilane azeotrope is 40-60wt% and the content of silicon tetrachloride is 30-55wt%.
Preferably, the reaction time in step 1 is from 0.5 to 1h.
Preferably, the ethanol and the hydrogen chloride are separated in the step 1 through distillation and reflux, wherein the temperature of the distillation is 50-70 ℃, and the time of the reflux is 2-4 hours.
Preferably, in the step 1, the molar ratio of the alcohol to the water in the alcohol-water solution is 10-13:0.4-0.8.
Preferably, in the step 2, the molar ratio of the alcohol to the water in the alcohol-water solution is 10-13:1-2, and the alcohol in the alcohol-water solution is the same as the alcohol used in the alcohol-water solution in the step 1; the alcohol is selected from methanol, ethanol or glycol, and on one hand, the alcohol plays a role of a solvent, and on the other hand, the alcohol plays a role of alcoholysis of the raw material with silicon tetrachloride.
Preferably, the reaction time in step 2 is 0.5 to 1h.
Preferably, the mass ratio of the aqueous alcohol solution and the chlorosilane azeotrope which are added dropwise in the step 1 and the step 2 is 0.8-1.6: 1, a step of; and the mass of water in the alcohol-water solution added in the step 1 is smaller than that in the alcohol-water solution added in the step 2.
The silicon tetrachloride is subjected to severe hydrolysis reaction in the environment of a large amount of water, hydrogen chloride generated by the reaction is dissolved in the water to form an acid environment, the silicon tetrachloride is more unfavorable for hydrolysis, the normal reaction is relieved and protected to a certain extent under the condition of the alcohol and the addition amount of the alcohol, the direct hydrolysis degree of the silicon tetrachloride is smaller, the proportion of tetraethoxysilane generated by alcoholysis is larger, and then the tetraethoxysilane is reacted with the water to hydrolyze to generate silica gel, so that the water content in the second alcohol aqueous solution is larger than that in the first alcohol aqueous solution.
Preferably, the alcohol-alkali solution is a mixed solution of alcohol, alkali and water, and the molar ratio of the alcohol to the alkali to the water is 2-4:3×10 -3 ~3×10 -2 : 0.01-0.1, wherein the alcohol used in the alcohol-alkali solution is the same as the alcohol in the alcohol-water solution in the step 1; the alkali is at least one of sodium hydroxide and ammonia water; and 3, adding the alkali alkoxide solution to the pH value of the silica sol to be 3.5-5.
Preferably, the washing in step 3 is washing with water.
Preferably, the time for standing the gel in the step 3 is 0.5-3 hours.
In certain aspects, in the step 3, an alcohol alkali solution is added into the silica sol, and after the mixture is stirred uniformly, the fiber material is added for full impregnation, then the mixture is left to stand for gelation, and after the gelation, the solvent replacement is carried out, so that the silica wet gel material is obtained.
Preferably, the solvent for solvent replacement is n-hexane, hexamethyldisiloxane or ethanol, and the solvent replacement process is soaking in the solvent for 24-48 h.
Preferably, the fiber material is short fiber or fiber felt, the short fiber is at least one of short aramid fiber, short basalt fiber, short glass fiber and short carbon fiber, and the fiber felt is one of basalt fiber felt, glass fiber felt, ceramic fiber felt and carbon fiber felt;
preferably, step 3 further comprises a step of removing the excess gel.
Preferably, the drying in the step 4 is normal pressure drying or supercritical drying; the normal pressure drying comprises freeze drying and spray drying; the spray drying temperature is 120-140 ℃, and the air inlet quantity is 100%; the supercritical drying medium is carbon dioxide or ethanol.
In a second aspect of the present invention, there is provided a superhydrophobic silica aerogel material prepared by the method of any of the above.
According to the invention, the temperature is controlled, water is introduced in a plurality of steps in the reaction process, the hydrolysis rate of silicon tetrachloride and trimethylchlorosilane in the chlorosilane azeotrope is controlled, the silicon tetrachloride gel skeleton building process is not influenced, and uniform grafting on the surface of the formed silica sol after the trimethylchlorosilane is hydrolyzed is ensured, so that the sol preparation and the sol hydrophobic modification process are synchronously carried out. The technical scheme of the invention has the following beneficial effects:
(1) The method of the invention prepares the super-hydrophobic silica aerogel material by taking the chlorosilane azeotrope as a raw material, solves the problems of the existing hydrophobic silica aerogel preparation process that an additional hydrophobic modifier is needed, the preparation process is complex and the preparation cost is high, not only realizes the recycling utilization of the chlorosilane azeotrope, but also gives the methylchlorosilane azeotrope higher economic value.
(2) The invention solves the problems of difficult gelation and poor hydrophobic modification effect in the process of preparing aerogel by using chlorosilane azeotrope by controlling the reaction temperature and introducing water in multiple steps, and finally prepares the super-hydrophobic silica aerogel with excellent heat insulation performance and super-hydrophobic characteristic.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully in connection with the embodiments of the present application, and it is apparent that the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present application based on the embodiments herein.
Example 1
Step 1, dropwise adding 240g of chlorosilane azeotrope (mainly comprising 40wt% of trimethylchlorosilane and 55wt% of silicon tetrachloride) into 200g of ethanol water solution (the molar ratio of ethanol to water is 13:0.6) below 10 ℃, reacting for 1h below 10 ℃, continuously discharging generated hydrogen chloride gas in the reaction process, heating to 60 ℃ for distillation after the reaction, and refluxing for 3h to obtain a reaction solution.
And step 2, dropwise adding 200g of ethanol water solution (the molar ratio of ethanol to water is 13:1.5) into the reaction solution, and continuously discharging generated hydrogen chloride gas in the reaction process at the temperature of below 10 ℃ for reaction for 1h to obtain the hydrophobic silica sol.
Step 3, an ethanol alkali solution (the molar ratio of ethanol, sodium hydroxide and water is 3:1.65X10) below 10 DEG C -2 :0.055 To the siliconAnd in the sol, standing for 2 hours until the pH value of the silica sol is 4, performing gel, crushing the obtained gel to a micron level after the gel is formed, and washing the gel with 300ml of pure water for 2 times to obtain the silica wet gel material.
And step 4, finally, drying the silica wet gel material to obtain the super-hydrophobic silica aerogel powder.
Example 2
Step 1, dropwise adding 240g of chlorosilane azeotrope (40 wt% of trimethylchlorosilane and 55wt% of silicon tetrachloride) into 200g of ethanol water solution (the molar ratio of ethanol to water is 13:0.4) below 10 ℃, reacting for 1h below 10 ℃, continuously discharging generated hydrogen chloride gas in the reaction process, heating to 60 ℃ for distillation after the reaction, and refluxing for 3h to obtain a reaction solution;
step 2, dropwise adding 200g of ethanol water solution (the molar ratio of ethanol to water is 13:1) into the reaction solution, and reacting for 1h at the temperature below 10 ℃, and continuously discharging generated hydrogen chloride gas in the reaction process to obtain hydrophobic silica sol;
step 3, an ethanol alkali solution (the molar ratio of ethanol, sodium hydroxide and water is 3:1.65X10) below 10 DEG C -2 :0.055 Adding the silica sol into the silica sol until the pH value of the silica sol is 4, standing for 2 hours for gelation, crushing the obtained gel to a micron level after gelation, and washing the gel with 300ml of pure water for 2 times to obtain a silica wet gel material;
and step 4, finally, drying the silica wet gel material to obtain the super-hydrophobic silica aerogel powder.
Example 3
Step 1, dropwise adding 240g of chlorosilane azeotrope (40 wt% of trimethylchlorosilane and 55wt% of silicon tetrachloride) into 200g of ethanol water solution (the molar ratio of ethanol to water is 13:0.8) below 10 ℃, reacting for 1h below 10 ℃, continuously discharging generated hydrogen chloride gas in the reaction process, heating to 60 ℃ for distillation after the reaction, and refluxing for 3h to obtain a reaction solution;
step 2, dropwise adding 200g of ethanol water solution (the molar ratio of ethanol to water is 13:1.0) into the reaction solution, and continuously discharging generated hydrogen chloride gas in the reaction process at the temperature of below 10 ℃ for reaction for 1h to obtain hydrophobic silica sol;
step 3, an ethanol alkali solution (the molar ratio of ethanol, sodium hydroxide and water is 3:1.65X10) below 10 DEG C -2 :0.055 Adding the silica sol into the silica sol until the pH value of the silica sol is 4, standing for 2 hours for gelation, crushing the obtained gel to a micron level after gelation, and washing the gel with 300ml of pure water for 2 times to obtain a silica wet gel material;
and step 4, finally, drying the silica wet gel material to obtain the super-hydrophobic silica aerogel powder.
Example 4
Step 1, dropwise adding 240g of chlorosilane azeotrope (40 wt% of trimethylchlorosilane and 55wt% of silicon tetrachloride) into 200g of ethanol water solution (the molar ratio of ethanol to water is 13:0.6) below 10 ℃, reacting for 1h below 10 ℃, continuously discharging generated hydrogen chloride gas in the reaction process, heating to 60 ℃ for distillation after the reaction, and refluxing for 3h to obtain a reaction solution;
step 2, dropwise adding 200g of ethanol water solution (the molar ratio of ethanol to water is 13:1.5) into the reaction solution, and continuously discharging generated hydrogen chloride gas in the reaction process at the temperature of below 10 ℃ for reaction for 1h to obtain hydrophobic silica sol;
step 3, an ethanol alkali solution (the molar ratio of ethanol, sodium hydroxide and water is 3:1.65X10) below 10 DEG C -2 :0.055 Adding the gel into the silica sol until the pH value of the silica sol is 4, standing for 2 hours to gel, crushing the gel to a micron level after the gel is formed, and washing the gel with 300ml of pure water for 2 times;
adding a glass fiber felt into the silica sol, fully soaking, standing for 2 hours for gelation, and after gelation, sequentially carrying out solvent replacement in water and n-hexane to obtain a silica wet gel material;
and step 4, finally, drying the silica wet gel material to obtain the silica aerogel felt.
Comparative example 1
Step 1, dropwise adding 240g of chlorosilane azeotrope (40 wt% of trimethylchlorosilane and 45wt% of silicon tetrachloride) into 200g of alcohol water solution (the molar ratio of ethanol to water is 13:0.6) at 10 ℃, reacting for 1h at 15 ℃, then heating to 60 ℃ for distillation, refluxing for 3h, and continuously discharging generated hydrogen chloride gas in the reaction process;
step 2, 200g of alcohol water solution (the molar ratio of ethanol to water is 13:1.5) is dripped into the reaction solution, the reaction is carried out for 1h at 10 ℃, and the generated hydrogen chloride gas is continuously discharged in the reaction process, so that hydrophobic silica sol is obtained;
step 3, alcohol alkali solution (molar ratio of ethanol, alkali and water is 3:1.65X10 -2 :0.055 Adding the silica sol into the silica sol until the pH value of the silica sol is 4, standing for 2 hours for gelation, crushing the obtained gel into micron-sized particles after gelation, and washing the gel with 300ml of pure water for 2 times to obtain a silica wet gel material;
and step 4, finally, drying the silica wet gel material to obtain the super-hydrophobic silica aerogel material.
Comparative example 2
Step 1, dropwise adding 240g of chlorosilane azeotrope (40 wt% of trimethylchlorosilane and 55wt% of silicon tetrachloride) into 200g of ethanol water solution (the molar ratio of ethanol to water is 13:1.5) below 10 ℃, reacting for 1h below 10 ℃, continuously discharging generated hydrogen chloride gas in the reaction process, heating to 60 ℃ for distillation after the reaction, and refluxing for 3h to obtain a reaction solution;
step 2, dropwise adding 200g of ethanol water solution (the molar ratio of ethanol to water is 13:0.6) into the reaction solution, and continuously discharging generated hydrogen chloride gas in the reaction process at the temperature of below 10 ℃ for reaction for 1h to obtain hydrophobic silica sol;
step 3, an ethanol alkali solution (the molar ratio of ethanol, sodium hydroxide and water is 3:1.65X10) below 10 DEG C -2 :0.055 Adding the silica sol into the silica sol until the pH value of the silica sol is 4, standing for 2 hours for gelation, crushing the obtained gel to a micron level after gelation, and washing the gel with 300ml of pure water for 2 times to obtain a silica wet gel material;
and step 4, finally, drying the silica wet gel material to obtain the super-hydrophobic silica aerogel powder.
Test results
The silica aerogel materials prepared in the above examples and comparative examples were subjected to performance tests, and the results are shown in the following table.
Table 1 test of the performance of the example and comparative example super-hydrophobic silica
From the test results, the super-hydrophobic silica aerogel prepared by the embodiment of the invention has the advantages of larger specific surface, smaller heat conductivity coefficient, better heat insulation performance, larger hydrophobic angle, smaller rolling angle and better super-hydrophobicity. According to the invention, the comparative example has the advantages that the reaction temperature is higher, the hydrolysis rate of silicon tetrachloride and trimethylchlorosilane in the chlorosilane azeotrope is larger, the polymerization speed of silicon tetrachloride is higher after hydrolysis, the gel effect is poorer, the hydrophobization can not be realized better, and the prepared aerogel has poorer heat insulation and hydrophobic effects.
Claims (10)
1. The preparation method of the super-hydrophobic silica aerogel material is characterized by comprising the following steps of:
step 1, dropwise adding chlorosilane azeotrope into an alcohol water solution for reaction, continuously discharging generated hydrogen chloride in the reaction process, and separating ethanol and hydrogen chloride after the reaction to obtain a reaction solution;
step 2, dropwise adding another alcohol-water solution into the reaction solution again for reaction, and continuously discharging generated hydrogen chloride gas in the reaction process to obtain hydrophobic silica sol;
step 3, adding an alcohol alkali solution into the hydrophobic silica sol, uniformly stirring, standing for gel, and washing after gel to obtain a silica wet gel material;
and step 4, drying to obtain the super-hydrophobic silica aerogel material.
2. The method for preparing the super-hydrophobic silica aerogel material according to claim 1, wherein the content of trimethylchlorosilane in the chlorosilane azeotrope in the step 1 is 40-60wt% and the content of silicon tetrachloride is 30-55wt%.
3. The method for preparing a superhydrophobic silica aerogel material according to claim 1, wherein the molar ratio of alcohol to water in the alcohol-water solution in step 1 is 10-13:0.4-0.8.
4. The method for preparing a superhydrophobic silica aerogel material according to claim 1, wherein the molar ratio of alcohol to water in the other alcohol-water solution in the step 2 is 10-13:1-2.
5. The method for preparing the super-hydrophobic silica aerogel material according to claim 1, wherein the mass ratio of the aqueous alcohol solution dropwise added in the step 1 and the step 2 to the chlorosilane azeotrope is 0.8-1.6:1; the reaction temperature in the step 1 and the step 2 is 0-10 ℃.
6. The method for preparing a superhydrophobic silica aerogel material according to claim 5, wherein the mass of water in the aqueous alcohol solution added in step 1 is smaller than the mass of water in the aqueous alcohol solution added in step 2; the alcohol is selected from methanol, ethanol or glycol.
7. The method for preparing a superhydrophobic silica aerogel material according to claim 1, wherein in the step 3, the alcohol-alkali solution is a mixed solution of alcohol, alkali and water, and the molar ratio of the alcohol to the alkali to the water is 2-4:3×10 -3 ~3×10 -2 :0.01 to 0.1; the alcohol is selected from methanol, ethanol or glycol.
8. The method for preparing a superhydrophobic silica aerogel material according to claim 1, wherein the alcohol alkali solution is added in the step 3 until the pH of the silica sol is 3.5-5.
9. The method for preparing the super-hydrophobic silica aerogel material according to claim 1, wherein in the step 3, an alcohol alkali solution is added into the silica sol, the mixture is stirred uniformly, a fiber material is added for full impregnation, then the mixture is left to stand for gelation, and solvent replacement is carried out after the gelation, so that the silica wet gel material is obtained.
10. A superhydrophobic silica aerogel material prepared by the method of any of claims 1-9.
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