CN115010140B - Preparation method of super-hydrophobic silica aerogel - Google Patents
Preparation method of super-hydrophobic silica aerogel Download PDFInfo
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- CN115010140B CN115010140B CN202210840025.7A CN202210840025A CN115010140B CN 115010140 B CN115010140 B CN 115010140B CN 202210840025 A CN202210840025 A CN 202210840025A CN 115010140 B CN115010140 B CN 115010140B
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- silica aerogel
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 206
- 239000004965 Silica aerogel Substances 0.000 title claims abstract description 114
- 230000003075 superhydrophobic effect Effects 0.000 title claims abstract description 90
- 238000002360 preparation method Methods 0.000 title claims abstract description 26
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 80
- 239000000741 silica gel Substances 0.000 claims abstract description 42
- 229910002027 silica gel Inorganic materials 0.000 claims abstract description 42
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims abstract description 32
- 239000004964 aerogel Substances 0.000 claims abstract description 32
- 239000002243 precursor Substances 0.000 claims abstract description 32
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 31
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 claims abstract description 30
- 229910000041 hydrogen chloride Inorganic materials 0.000 claims abstract description 30
- 239000000178 monomer Substances 0.000 claims abstract description 27
- 238000001035 drying Methods 0.000 claims abstract description 26
- 239000005046 Chlorosilane Substances 0.000 claims abstract description 24
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical compound Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 claims abstract description 24
- 238000000034 method Methods 0.000 claims abstract description 20
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 20
- -1 alcohol compound Chemical class 0.000 claims abstract description 9
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 70
- IJOOHPMOJXWVHK-UHFFFAOYSA-N chlorotrimethylsilane Chemical compound C[Si](C)(C)Cl IJOOHPMOJXWVHK-UHFFFAOYSA-N 0.000 claims description 48
- 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 description 25
- 239000005049 silicon tetrachloride Substances 0.000 claims description 25
- LIKFHECYJZWXFJ-UHFFFAOYSA-N dimethyldichlorosilane Chemical compound C[Si](C)(Cl)Cl LIKFHECYJZWXFJ-UHFFFAOYSA-N 0.000 claims description 24
- 239000005055 methyl trichlorosilane Substances 0.000 claims description 24
- JLUFWMXJHAVVNN-UHFFFAOYSA-N methyltrichlorosilane Chemical compound C[Si](Cl)(Cl)Cl JLUFWMXJHAVVNN-UHFFFAOYSA-N 0.000 claims description 24
- 239000005051 trimethylchlorosilane Substances 0.000 claims description 24
- 239000011148 porous material Substances 0.000 claims description 23
- 239000000377 silicon dioxide Substances 0.000 claims description 16
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 15
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 15
- 238000010992 reflux Methods 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 12
- 230000035484 reaction time Effects 0.000 claims description 11
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 7
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 239000002105 nanoparticle Substances 0.000 claims description 4
- 239000000203 mixture Substances 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- 230000002209 hydrophobic effect Effects 0.000 abstract description 28
- 239000002904 solvent Substances 0.000 abstract description 18
- 239000003054 catalyst Substances 0.000 abstract description 8
- 238000009776 industrial production Methods 0.000 abstract description 3
- 230000002349 favourable effect Effects 0.000 abstract 1
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 24
- 239000000243 solution Substances 0.000 description 18
- LRHPLDYGYMQRHN-UHFFFAOYSA-N N-Butanol Chemical compound CCCCO LRHPLDYGYMQRHN-UHFFFAOYSA-N 0.000 description 12
- 239000000499 gel Substances 0.000 description 10
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 9
- 238000009413 insulation Methods 0.000 description 8
- 239000000463 material Substances 0.000 description 8
- 238000001291 vacuum drying Methods 0.000 description 8
- 239000002131 composite material Substances 0.000 description 7
- 235000012239 silicon dioxide Nutrition 0.000 description 7
- UHOVQNZJYSORNB-UHFFFAOYSA-N Benzene Chemical compound C1=CC=CC=C1 UHOVQNZJYSORNB-UHFFFAOYSA-N 0.000 description 6
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 6
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 description 6
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 description 6
- 239000002994 raw material Substances 0.000 description 6
- 238000001179 sorption measurement Methods 0.000 description 6
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 description 6
- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 5
- 230000004048 modification Effects 0.000 description 5
- 238000012986 modification Methods 0.000 description 5
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 4
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 description 4
- WYURNTSHIVDZCO-UHFFFAOYSA-N Tetrahydrofuran Chemical compound C1CCOC1 WYURNTSHIVDZCO-UHFFFAOYSA-N 0.000 description 4
- 239000002585 base Substances 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 239000004811 fluoropolymer Substances 0.000 description 4
- 229920002313 fluoropolymer Polymers 0.000 description 4
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 239000011240 wet gel Substances 0.000 description 4
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 3
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 3
- 238000006555 catalytic reaction Methods 0.000 description 3
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 description 3
- 239000003960 organic solvent Substances 0.000 description 3
- 235000019353 potassium silicate Nutrition 0.000 description 3
- 229910000029 sodium carbonate Inorganic materials 0.000 description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 3
- 238000000352 supercritical drying Methods 0.000 description 3
- 239000004094 surface-active agent Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
- 238000003917 TEM image Methods 0.000 description 2
- 239000003377 acid catalyst Substances 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- JYYOBHFYCIDXHH-UHFFFAOYSA-N carbonic acid;hydrate Chemical compound O.OC(O)=O JYYOBHFYCIDXHH-UHFFFAOYSA-N 0.000 description 2
- 239000003153 chemical reaction reagent Substances 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000032050 esterification Effects 0.000 description 2
- 238000005886 esterification reaction Methods 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- VKYKSIONXSXAKP-UHFFFAOYSA-N hexamethylenetetramine Chemical compound C1N(C2)CN3CN1CN2C3 VKYKSIONXSXAKP-UHFFFAOYSA-N 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 description 2
- 239000011259 mixed solution Substances 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000003607 modifier Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 2
- 235000017557 sodium bicarbonate Nutrition 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 description 2
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 description 1
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- ZFSFDELZPURLKD-UHFFFAOYSA-N azanium;hydroxide;hydrate Chemical compound N.O.O ZFSFDELZPURLKD-UHFFFAOYSA-N 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
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000007810 chemical reaction solvent Substances 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 239000008367 deionised water Substances 0.000 description 1
- 229910021641 deionized water Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000005538 encapsulation Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 125000004494 ethyl ester group Chemical group 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 239000004312 hexamethylene tetramine Substances 0.000 description 1
- 235000010299 hexamethylene tetramine Nutrition 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 239000008235 industrial water Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- BFXIKLCIZHOAAZ-UHFFFAOYSA-N methyltrimethoxysilane Chemical compound CO[Si](C)(OC)OC BFXIKLCIZHOAAZ-UHFFFAOYSA-N 0.000 description 1
- 150000007522 mineralic acids Chemical class 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 235000006408 oxalic acid Nutrition 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000004321 preservation Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 235000017550 sodium carbonate Nutrition 0.000 description 1
- 238000003980 solgel method Methods 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 description 1
- 238000002411 thermogravimetry Methods 0.000 description 1
- 238000005406 washing Methods 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
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/04—Particle morphology depicted by an image obtained by TEM, STEM, STM or AFM
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/64—Nanometer sized, i.e. from 1-100 nanometer
-
- 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
- C01P2006/16—Pore diameter
- C01P2006/17—Pore diameter distribution
Abstract
The invention discloses a preparation method of super-hydrophobic silica aerogel. The preparation method comprises the following steps: 1) Slowly dripping an alcohol compound into chlorosilane at a selected temperature to generate an organosilicon monomer and hydrogen chloride, adding water, and removing the hydrogen chloride to obtain a silicon oxide aerogel precursor; adding water and a base catalyst into the solution containing the silica aerogel precursor obtained in the step 1), and performing polycondensation reaction to obtain silica gel; and (3) performing solvent replacement and drying treatment on the silica gel obtained in the step (2) to obtain the super-hydrophobic silica aerogel. The hydrophobic angle of the super-hydrophobic silica aerogel is 150-160 degrees. The preparation method of the super-hydrophobic silica aerogel provided by the invention has the advantages of low cost, simple process and low cost, and is favorable for large-scale industrial production.
Description
Technical Field
The invention relates to a preparation method of super-hydrophobic silica aerogel, and belongs to the technical field of nano materials.
Background
Aerogel materials are materials that are obtained by replacing the liquid component of the gel with a gas while maintaining the gel network from collapsing. As the silicon oxide aerogel which is discovered and commercialized at first, the silicon oxide aerogel has wide application prospect in the fields of heat insulation, adsorption, catalysis, optics and the like. After decades of development, various methods for preparing silica aerogel are invented successively. For example, patent CN106430219a discloses a method for preparing silica aerogel with low cost, which uses cheap industrial water glass as a precursor, water as a reaction solvent, oxalic acid as an acid catalyst, and prepares the silica aerogel through a normal pressure drying process. Patent CN107572538A discloses a hydrophilic silica aerogel material and a preparation method thereof, wherein a silicon source, water, an acid catalyst and an alkaline catalyst are mixed and stirred to form gel, and the gel is aged and freeze-dried to obtain the hydrophilic silica aerogel material, which has high porosity (82-99.6%) and high specific surface area (300-1300 m) 2 /g). Chen Xingming et al (HCl-NH) 3 Two-component catalytic orthosilicic acidRapid preparation of SiO by ethyl ester 2 Aerogel [ J]Modern chemical industry, 2003.) uses Tetraethoxysilane (TEOS) as raw material, water and ethanol as solvent, hydrochloric acid and ammonia water as catalyst, and adopts sol-gel method to prepare SiO 2 Aerogel, prepared SiO 2 The aerogel has a nano porous structure, the skeleton particles are 15-20 nm, and the hole size is 10-30 nm.
Although the silicon oxide aerogel can be rapidly synthesized by taking water glass, methyl orthosilicate or ethyl orthosilicate as a silicon source, the silicon dioxide has hydrophilicity, the pure silicon dioxide aerogel can generate huge capillary force on water molecules due to the nano-scale pore structure of the silicon dioxide aerogel, the three-dimensional nano skeleton collapses due to gradual water absorption when the silicon dioxide aerogel is placed in the air, the porosity, the specific surface area and the pore volume of the aerogel can be rapidly reduced, and the excellent performances such as adsorption, catalysis and heat insulation are not existed. In order to increase the environmental resistance of silica aerogels, it is desirable to prepare silica aerogels that are hydrophobic or even superhydrophobic. The following three methods are common for preparing hydrophobic silica aerogels:
1. hydrophilic silica wet gels are chemically modified with hydrophobic reagents. For example, patent CN109850909a discloses a normal pressure preparation method of super-hydrophobic silica aerogel, which comprises mixing ethyl orthosilicate, absolute ethanol and water to obtain a mixed solution, adjusting the pH to 2-3, adding DMF and adjusting the pH of the reaction solution to 5-6, standing to form gel, soaking the gel with a mixed solution of hexamethylenetetramine, DMF and ethanol for modification, and finally drying under normal pressure to obtain super-hydrophobic SiO 2 An aerogel. Patent CN101844771a discloses a method for preparing a superhydrophobic silica aerogel under normal pressure by adding a first surface modifier, a second surface modifier, a nonpolar organic solvent and an inorganic acid to a water glass solution and reacting to prepare a hydrophobic silica wet gel, and washing and drying the hydrophobic silica wet gel to obtain the superhydrophobic silica aerogel. The super-hydrophobic silica gel can be obtained under the condition of not affecting the structure of the silica aerogel by utilizing the modification of the hydrophobic reagent, but the method has the advantages of complex process flow, multiple solvent replacement, long period, high cost and limitation of the silicaLarge scale application of aerogels.
2. And the hydrophobic material is compounded with the hydrophilic silica aerogel to obtain the hydrophobic silica aerogel. For example, patent CN112079618A discloses a preparation method of a modified silica aerogel thermal insulation sheet, in which orthosilicate is used as a silicon source, the silica aerogel thermal insulation sheet is obtained after the orthosilicate is compounded with a fiber matrix, a layer of hydrophobic encapsulation coating is prepared on the surface of the silica aerogel thermal insulation sheet by a roll coating, brush coating or spray coating mode, and the coating is cured to obtain the modified silica aerogel thermal insulation sheet. Patent CN108504006a discloses a silica aerogel/organic fluoropolymer composite film, a preparation method and application thereof, the silica aerogel micro powder and the organic fluoropolymer cross-linking agent are fully and uniformly mixed and rolled to obtain the silica aerogel/organic fluoropolymer composite film, and the silica aerogel/organic fluoropolymer composite film of the invention has hydrophobicity and can be used in air for a long time. However, the hydrophobic material composite modified hydrophilic silica aerogel inevitably reduces the content of the silica aerogel, the density of the composite body is increased, the performances such as heat insulation and adsorption are reduced, and the application range of the silica aerogel is limited.
3. The super-hydrophobic silica aerogel is prepared by methyl-containing siloxane. For example, patent CN109052415a discloses a silica aerogel based on MTMS and a preparation method thereof, deionized water and cetyltrimethylammonium bromide are mixed, then methyltrimethoxysilane is added, ammonia water gel is added after stirring at constant temperature, and the wet gel is washed and dried to obtain the super-hydrophobic silica aerogel. Patent CN105731470a discloses a preparation method of silica aerogel composite material, which comprises mixing and stirring surfactant, methanol and acetic acid solution to dissolve the surfactant, adding DMF, MTMS and dmdmdms, placing in a constant temperature magnetic stirrer to hydrolyze thoroughly, adding alkali liquor to adjust pH to form gel, aging and replacing solvent, and drying at normal pressure to obtain elastic super-hydrophobic aerogel. The preparation of the super-hydrophobic silica aerogel by using methyl-containing siloxane can reduce the steps of the process flow. However, the added surfactant is not easily removed, and the methyl siloxane-containing raw material is expensive, making the silica aerogel expensive.
The silicon dioxide has hydrophilicity, so the pure silicon dioxide aerogel has huge capillary force on water molecules due to the nano-scale pore structure, and the three-dimensional nano skeleton collapses and gradually fails due to gradual adsorption of water molecules in the air. The superhydrophobic silica aerogel is generally obtained by hydrolytic polycondensation of an organosilicon precursor and then hydrophobic modification, which not only increases the process and cost, but also increases the use of an organic solvent in the solvent replacement step. Therefore, the method for synthesizing the super-hydrophobic silica aerogel by using cheap raw materials is of great significance and is rapid and low in cost.
Disclosure of Invention
The invention mainly aims to provide a preparation method of super-hydrophobic silica aerogel, which solves the technical problems of high preparation cost, complex process and high organic solvent consumption of the super-hydrophobic silica aerogel in the prior art.
In order to achieve the purpose of the invention, the technical scheme adopted by the invention comprises the following steps:
the embodiment of the invention provides a preparation method of super-hydrophobic silica aerogel, which comprises the following steps:
1) Slowly dripping an alcohol compound into chlorosilane at a selected temperature to generate an organosilicon monomer and hydrogen chloride, adding water, and removing the hydrogen chloride to obtain a silicon oxide aerogel precursor;
2) Adding water and a base catalyst into the solution containing the silica aerogel precursor obtained in the step 1), and performing polycondensation reaction to obtain silica gel;
3) And (3) performing solvent replacement and drying treatment on the silica gel obtained in the step (2) to obtain the super-hydrophobic silica aerogel.
The embodiment of the invention also provides the super-hydrophobic silica aerogel prepared by the method.
Further, the super-hydrophobic silica aerogel comprises a three-dimensional porous network structure formed by interconnecting silica nanoparticles, wherein the three-dimensional porous network structure comprises micropores with the pore diameter below 2nm, mesopores with the pore diameter of 2-50 nm and macropores with the pore diameter of 50-50 mu m, the hydrophobic angle of the super-hydrophobic silica aerogel is 150-160 degrees, and the chemical composition of the silica nanoparticles comprises any one or a combination of two of silicon dioxide and polymethyl siloxane.
The embodiment of the invention also provides application of the super-hydrophobic silica aerogel, and has great application prospects in the fields of heat insulation, heat preservation, adsorption, composite materials, environmental protection, catalysis and the like.
Compared with the prior art, the invention has the advantages that:
1) The super-hydrophobic silica aerogel provided by the invention is directly prepared from chlorosilane monomers, has low cost, simple process and low cost, and is beneficial to large-scale industrial production;
2) The super-hydrophobic silica aerogel provided by the invention has super-hydrophobicity without a hydrophobic modification process, and the hydrophobic angle is 150-160 degrees.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the embodiments or the description of the prior art will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments described in the present invention, and other drawings may be obtained according to the drawings without inventive effort to those skilled in the art.
FIG. 1 is a schematic illustration of a process for preparing a superhydrophobic silica aerogel according to an exemplary embodiment of the invention;
FIG. 2 is a graph showing the desorption of nitrogen from the super-hydrophobic silica aerogel obtained in example 1 of the present invention;
FIG. 3 is a graph showing pore size distribution of the superhydrophobic silica aerogel obtained in example 1 of the present invention;
FIG. 4 is a scanning electron micrograph of the superhydrophobic silica aerogel obtained in example 1 of the invention;
FIG. 5 is a transmission electron micrograph of the superhydrophobic silica aerogel obtained in example 1 of the invention;
FIG. 6 is a schematic view showing the contact angle of the superhydrophobic silica aerogel obtained in example 1 of the present invention;
FIG. 7 is a scanning electron micrograph of the superhydrophobic silica aerogel obtained in example 2 of the invention;
FIG. 8 is a transmission electron micrograph of a superhydrophobic silica aerogel obtained in example 2 of the invention;
FIG. 9 is a graph showing the TG pattern of the super-hydrophobic silica aerogel obtained in example 2 of the present invention;
FIG. 10 is a schematic view showing the contact angle of the superhydrophobic silica aerogel obtained in example 2 of the invention;
FIG. 11 is an optical photograph of the superhydrophobic silica aerogel obtained in example 2 of the present invention.
Detailed Description
In view of the shortcomings in the prior art, the inventor of the present invention has provided a technical scheme of the present invention through long-term research and a great deal of practice, mainly through the esterification and polycondensation reaction of chlorosilane to obtain silica gel, then through the solvent replacement and drying steps to obtain super-hydrophobic silica aerogel, and a series of applications of the super-hydrophobic silica aerogel. The technical scheme, the implementation process, the principle and the like are further explained as follows.
The embodiment of the invention provides a preparation method of super-hydrophobic silica aerogel, which comprises the following steps:
1) Slowly dripping an alcohol compound into chlorosilane at a selected temperature to generate an organosilicon monomer and hydrogen chloride, adding water, and removing the hydrogen chloride to obtain a silicon oxide aerogel precursor;
2) Adding water and a base catalyst into the solution containing the silica aerogel precursor obtained in the step 1), and performing polycondensation reaction to obtain silica gel;
3) And (3) performing solvent replacement and drying treatment on the silica gel obtained in the step (2) to obtain the super-hydrophobic silica aerogel.
In some more specific embodiments, referring to fig. 1, the preparation method may include the following steps:
1) Slowly dripping excessive alcohol compounds into chlorosilane with a certain proportion under the condition of water bath constant temperature to generate organic silicon monomers and hydrogen chloride, adding water with a certain proportion, removing the hydrogen chloride through reflux, and cooling to room temperature to obtain a silicon oxide aerogel precursor;
2) Adding water and a base catalyst into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel;
3) And 3) performing solvent replacement and drying on the silica gel obtained in the step 2) to obtain the super-hydrophobic silica aerogel.
In some embodiments, in step 1), the selected temperature of the constant temperature of the water bath is between 5 and 30 ℃, preferably between 15 and 25 ℃.
In some embodiments, the alcohol compound includes any one or a combination of two or more of methanol, ethanol, propanol, butanol, etc., and is not limited thereto.
In some embodiments, the chlorosilane includes any one or a combination of two or more of trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane, silicon tetrachloride, and the like, and is not limited thereto.
Further, the mole percentage of trimethylchlorosilane in the chlorosilane is 0-20%, the mole percentage of dimethyldichlorosilane is 0-50%, the mole percentage of silicon tetrachloride is not more than 80%, and the balance consists of methyltrichlorosilane and silicon tetrachloride.
In some embodiments, in step 1), the molar ratio of the alcohol compound to chlorosilane is from 5 to 20:1, preferably from 5 to 10:1.
Further, the dropping rate of the alcohol compound is 20 to 2000mL/min, preferably 100 to 500mL/min.
Further, in step 1) a certain proportion of water is added, the molar ratio of water to chlorosilane is 1-4:1, preferably 1.5-3:1.
Further, the temperature of the reflux is 60-130 ℃, preferably 70-100 ℃; the time of the reflux is 1 to 12 hours, preferably 3 to 6 hours.
In some embodiments, in step 2), the molar ratio of water to chlorosilane added is 0-3:1, preferably 1-1.5:1.
Further, the base catalyst includes any one or a combination of two or more of sodium hydroxide, triethylamine, ammonia water, sodium carbonate, sodium bicarbonate, tetramethylammonium hydroxide, and the like, and is not limited thereto.
Further, the molar ratio of the alkali catalyst to the chlorosilane is 110 -4 1:1, preferably 10 -1 ～10 -3 ∶1。
In some embodiments, in step 2), the polycondensation reaction is carried out for a period of time ranging from 1 to 96 hours, preferably from 48 to 72 hours, and the polycondensation reaction is carried out at a temperature ranging from 20 to 90 ℃, preferably from 60 to 80 ℃.
In some embodiments, in step 3), the replacement solvent used for the solvent replacement includes any one or a combination of two or more of water, ethanol, acetone, n-hexane, benzene, tetrahydrofuran, dimethyl sulfoxide, and the like, and is not limited thereto.
Further, the number of solvent substitutions is 3 to 10.
Further, the drying treatment includes any one or a combination of two or more of normal pressure drying, vacuum drying, supercritical drying, and the like.
Further, the temperature of the normal pressure drying is 20-120 ℃, preferably 30-60 ℃ and the drying time is 6-48 h.
Further, the vacuum drying technology comprises freeze vacuum drying, normal temperature vacuum drying and the like, wherein the cold trap temperature of the freeze vacuum drying is-45 to-80 ℃, the vacuum degree is less than 0.1kPa, and the drying time is 6 to 48 hours. The temperature of normal temperature vacuum drying is room temperature, and the vacuum degree is less than 0.1kPa.
Further, the supercritical drying comprises supercritical CO 2 Any one of supercritical ethanol and the like, wherein the supercritical drying specifically can comprise: and (3) replacing liquid components in the gel material with the supercritical fluid under the supercritical environment of the specific supercritical fluid, wherein the drying time is 12-48 h, and obtaining the aerogel material.
In summary, the silica gel is obtained through esterification and polycondensation of cheap raw material chlorosilane, and then the super-hydrophobic silica aerogel is obtained through solvent replacement and drying steps. The method not only reduces the preparation cost of the super-hydrophobic silica aerogel, but also shortens the preparation period, and lays a foundation for large-scale application of the silica aerogel.
Another aspect of the embodiments of the present invention also provides a superhydrophobic silica aerogel prepared by the foregoing preparation method.
Further, the super-hydrophobic silica aerogel is composed of a three-dimensional porous network structure formed by interconnecting, wherein the three-dimensional porous network structure comprises micropores with the aperture below 2nm, mesopores with the aperture of 2-50 nm and macropores with the aperture of 50 nm-50 mu m; the composition of the super-hydrophobic silica aerogel includes any one or a combination of two of silica and polymethylsiloxane, etc., but is not limited thereto.
Further, the super-hydrophobic silica aerogel has super-hydrophobicity, and the hydrophobic angle is 150-160 degrees.
In some embodiments, the super-hydrophobic silica aerogel has a density of 30 to 300mg/cm 3 Preferably 50 to 200mg/cm 3 。
Further, the specific surface area of the super-hydrophobic silica aerogel is 100-1200 m 2 Preferably 400 to 800m 2 /g。
Further, the pore volume of the super-hydrophobic silica aerogel is 0.5-5 cm 3 Preferably 1 to 3cm 3 /g。
Further, the porosity of the super-hydrophobic silica aerogel is 70 to 99%, preferably 75 to 99%, and particularly preferably 85 to 95%.
Further, the use temperature of the super-hydrophobic silica aerogel is-196-250 ℃, preferably-50-200 ℃.
Further, the thermal conductivity of the super-hydrophobic silica aerogel is 0.015 to 0.04W/(m.K), preferably 0.018 to 0.03W/(m.K).
In conclusion, the preparation method of the super-hydrophobic silica aerogel provided by the invention has the advantages of simple process, low raw material cost and low cost, and is beneficial to large-scale industrial production.
The technical solution of the present invention will be described in further detail below with reference to a number of preferred embodiments and accompanying drawings, and it is apparent that the described embodiments are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention. The experimental methods, in which specific conditions are not noted in the following examples, are generally conducted under conventional conditions or under conditions recommended by the manufacturer.
Example 1
(1) Slowly dropwise adding methanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride under the condition of constant temperature (5 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 130 ℃ for 1 hour), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein, the dropping rate of methanol is 50mL/min. The molar ratio of water, methanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 1:5:0.1:0.2:0.3:0.4.
(2) Adding water and ammonia water into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein the mole ratio of water to ammonia water to chlorosilane monomer is 1.5:10 -4 The polycondensation reaction time is 48h, and the temperature is 60 ℃.
(3) And 2) replacing the silica gel obtained in the step 2) with an ethanol solvent for 6 times, and then drying with supercritical ethanol for 48 hours to obtain the super-hydrophobic silica aerogel.
The nitrogen adsorption and desorption curves of the super-hydrophobic silica aerogel obtained in the embodiment are shown in fig. 2, the pore size distribution is shown in fig. 3, the sem structure is shown in fig. 4, the tem image is shown in fig. 5, and the contact angle is shown in fig. 6. The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica aerogel obtained in this example are shown in table 1.
Example 2
(1) Slowly dropwise adding methanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (30 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 60 ℃ for 12 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein, the dropping speed of the methanol is 2000mL/min. The mol ratio of water, methanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 3:10:0:0:0.5:0.5.
(2) Adding water and sodium carbonate into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein the mole ratio of water to sodium carbonate to chlorosilane monomers is 1:10 -1 The polycondensation reaction time is 48h, and the temperature is 60 ℃.
(3) And 2) replacing the silica gel obtained in the step 2) with an ethanol solvent for 6 times, and then drying with supercritical carbon dioxide for 12 hours to obtain the super-hydrophobic silica aerogel.
The SEM structure of the superhydrophobic silica gel obtained in this example is shown in fig. 7, the tem image is shown in fig. 8, the thermogravimetric analysis image is shown in fig. 9, the contact angle is shown in fig. 10, and the hydrophobic optical photograph is shown in fig. 11. The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
Example 3
(1) Slowly dropwise adding ethanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (20 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 80 ℃ for 6 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein the dropping rate of the ethanol is 20mL/min. The mol ratio of water, ethanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 3:8:0.2:0.3:0.4:0.1.
(2) Adding water and triethylamine into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein water is triethylamineThe molar ratio of the chlorosilane monomers is 1.5:10 -3 The polycondensation reaction time is 48h, and the temperature is 20 ℃.
(3) And (3) replacing the silica gel obtained in the step (2) with ethanol and n-hexane solvent for 6 times, and then adopting normal-pressure drying (the temperature is 30 ℃) for 48 hours to obtain the super-hydrophobic silica aerogel.
The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
Example 4
(1) Slowly dropwise adding propanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (20 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 80 ℃ for 6 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein, the dropping rate of the propanol is 50mL/min. The mol ratio of water, propanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 3:10:0.1:0.1:0.4:0.4.
(2) Adding water and sodium hydroxide into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein the mole ratio of water to sodium hydroxide to chlorosilane monomer is 1.5:10 -3 The polycondensation reaction time is 1h, and the temperature is 90 ℃.
(3) And (3) replacing the silica gel obtained in the step (2) with an ethanol solvent for 6 times, and then drying at normal pressure (the temperature is 60 ℃) to obtain the super-hydrophobic silica aerogel.
The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
Example 5
(1) Slowly dropwise adding butanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (20 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 80 ℃ for 6 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein the dropping rate of butanol is 50mL/min. The mol ratio of water, propanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 3:10:0.1:0.1:0.3:0.5.
(2) Adding water and sodium bicarbonate into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein the mole ratio of water to sodium bicarbonate to chlorosilane monomers is 1.5:10 -3 The polycondensation reaction time is 48h, and the temperature is 60 ℃.
(3) And (3) replacing the silica gel obtained in the step (2) with a dimethyl sulfoxide solvent for 10 times, and then adopting normal-pressure drying (the temperature is 120 ℃) for 6 hours to obtain the super-hydrophobic silica aerogel.
The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
Example 6
(1) Slowly dropwise adding butanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (20 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 75 ℃ for 6 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein, the dropping speed of butanol is 50mL/min. The mol ratio of water, butanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 3:9:0.05:0.15:0.6:0.2.
(2) Adding water and tetramethyl ammonium hydroxide into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein the molar ratio of water to tetramethylammonium hydroxide to chlorosilane monomers is 1.5:10 -3 The polycondensation reaction time is 48h, and the temperature is 60 ℃.
(3) And 5) replacing the silica gel obtained in the step 2) with water, and then adopting freeze vacuum drying for 48 hours to obtain the super-hydrophobic silica aerogel.
The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
Example 7
(1) Slowly dropwise adding ethanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (20 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 75 ℃ for 6 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein the dropping rate of the ethanol is 50mL/min. The mol ratio of water, ethanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 3:10:0.1:0.2:0.5:0.2.
(2) Adding water and ammonia water into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein the mol ratio of water to ammonia water to chlorosilane monomer is 1.5:1:1, the polycondensation reaction time is 48 hours, and the temperature is 80 ℃.
(3) And 5 times of replacement of the silica gel obtained in the step 2) with water, and then vacuum drying at normal temperature for 6 hours to obtain the super-hydrophobic silica aerogel.
The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
Example 8
(1) Slowly dropwise adding ethanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (25 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 70 ℃ for 6 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein the dropping rate of the ethanol is 50mL/min. The mol ratio of water, ethanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 4:20:0.1:0.2:0.5:0.2.
(2) Adding water and ammonia water into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein the mole ratio of water to ammonia water to chlorosilane monomer is 1.5:10 -3 The polycondensation reaction time is 48h, and the temperature is 80 ℃ in the ratio of 1.
(3) And 5) replacing the silica gel obtained in the step 2) with acetone, and drying by adopting supercritical ethanol to obtain the super-hydrophobic silica aerogel.
The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
Example 9
(1) Slowly dropwise adding ethanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (15 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 100 ℃ for 6 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein the dropping rate of the ethanol is 50mL/min. The mol ratio of water, ethanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 3:10:0.1:0.2:0.5:0.2.
(2) Adding water and ammonia water into the silica aerogel precursor solution obtained in the step 1), and performing polycondensation reaction to obtain silica gel; wherein the mole ratio of water to ammonia water to chlorosilane monomer is 3:10 -3 The polycondensation reaction time is 72h, and the temperature is 80 ℃ in the ratio of 1.
(3) And 5) replacing the silica gel obtained in the step 2) with benzene and ethanol for 5 times, and drying by adopting supercritical ethanol to obtain the super-hydrophobic silica aerogel.
The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
Example 10
(1) Slowly dropwise adding ethanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at a constant temperature (20 ℃) in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride by refluxing (the temperature is 75 ℃ for 6 hours), and cooling to room temperature to obtain the silicon oxide aerogel precursor. Wherein the ethanol dropping rate is 50mL/min. The mol ratio of water, ethanol, trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride is 3:10:0.1:0.2:0.5:0.2.
(2) To the oxygen obtained in step 1)Adding water and ammonia water into the silicon oxide aerogel precursor solution, and performing polycondensation reaction to obtain silicon oxide gel; wherein the mole ratio of water to ammonia water to chlorosilane monomer is 1.5:10 -3 The polycondensation reaction time is 96 hours, and the temperature is 80 ℃ in the ratio of 1.
(3) And 3) replacing the silica gel obtained in the step 2) with tetrahydrofuran for 3 times, and then drying by adopting supercritical ethanol to obtain the super-hydrophobic silica aerogel.
The specific surface area, the hydrophobic angle, the pore volume, the density and other physical parameters of the superhydrophobic silica gel obtained in this example are shown in table 1.
TABLE 1 Structure and Performance parameters of the Superhydrophobic silica aerogels obtained in examples 1-10
| Examples | Hydrophobic angle | Specific surface area (m) 2 /g) | Pore volume (%) | Density (mg/cm) 3 ) |
| 1 | 155.5° | 120 | 0.6 | 117 |
| 2 | 157.3° | 196 | 5 | 30 |
| 3 | 158.6° | 977 | 1.3 | 54 |
| 4 | 151.0° | 546 | 1.1 | 280 |
| 5 | 150.5° | 351 | 4.3 | 105 |
| 6 | 160.0° | 636 | 0.5 | 300 |
| 7 | 150.0° | 587 | 4.7 | 251 |
| 8 | 159.9° | 1200 | 2.5 | 146 |
| 9 | 154.4° | 216 | 4.1 | 267 |
| 10 | 156.3° | 867 | 2.3 | 222 |
In addition, the inventor also adopts other raw materials and process conditions listed in the specification, and prepares a series of super-hydrophobic silica aerogel by referring to the modes of examples 1-10. It is found by testing that the super-hydrophobic silica aerogel also has various excellent properties described in the specification.
It should be understood that the foregoing is only a few embodiments of the present invention, and it should be noted that other modifications and improvements can be made by those skilled in the art without departing from the inventive concept of the present invention, which fall within the scope of the present invention.
Claims (7)
1. The preparation method of the super-hydrophobic silica aerogel is characterized by comprising the following steps:
1) Slowly dropwise adding ethanol into trimethylchlorosilane, dimethyldichlorosilane, methyltrichlorosilane and silicon tetrachloride at the constant temperature of 25 ℃ in a water bath to generate organosilicon monomers and hydrogen chloride, then adding water, removing the hydrogen chloride for 6 hours at the reflux temperature of 70 ℃, and cooling to room temperature to obtain a silicon oxide aerogel precursor, wherein the dropwise adding rate of the ethanol is 50mL/min, and the molar ratio of the water, the ethanol, the trimethylchlorosilane, the dimethyldichlorosilane, the methyltrichlorosilane and the silicon tetrachloride is 4:20:0.1:0.2:0.5:0.2;
2) Adding water into the silica aerogel precursor solution obtained in the step 1)And ammonia water, and obtaining silica gel through polycondensation reaction; wherein water: ammonia water: the molar ratio of chlorosilane monomers was 1.5:10 -3 :1, the polycondensation reaction time is 48 hours, and the temperature is 80 ℃;
3) And 5) replacing the silica gel obtained in the step 2) with acetone, and drying by adopting supercritical ethanol to obtain the super-hydrophobic silica aerogel.
2. The method of manufacturing according to claim 1, characterized in that: in the step 3), the supercritical ethanol drying time is 12-48 h.
3. The method of manufacturing according to claim 1, characterized in that: the super-hydrophobic silica aerogel comprises a three-dimensional porous network structure formed by mutually connecting silica nanoparticles, wherein the three-dimensional porous network structure comprises micropores with the pore diameter below 2nm, mesopores with the pore diameter of 2-50 nm and macropores with the pore diameter of 50 nm-50 mu m, and the chemical composition of the silica nanoparticles comprises any one or a combination of two of silica and polymethylsiloxane.
4. A method of preparation according to claim 3, characterized in that: the porosity of the super-hydrophobic silica aerogel is 70-99%.
5. The method of manufacturing according to claim 4, wherein: the porosity of the super-hydrophobic silica aerogel is 85-95%.
6. A method of preparation according to claim 3, characterized in that: the thermal conductivity of the super-hydrophobic silica aerogel is 0.015-0.04W/(m.K).
7. The method of manufacturing according to claim 6, wherein: the thermal conductivity of the super-hydrophobic silica aerogel is 0.018-0.03W/(m.K).
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