CN114988417B - Super-white silicon oxide aerogel, preparation method and application thereof - Google Patents
Super-white silicon oxide aerogel, preparation method and application thereof Download PDFInfo
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- CN114988417B CN114988417B CN202210839360.5A CN202210839360A CN114988417B CN 114988417 B CN114988417 B CN 114988417B CN 202210839360 A CN202210839360 A CN 202210839360A CN 114988417 B CN114988417 B CN 114988417B
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- silica aerogel
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- white silica
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- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 title claims abstract description 162
- 238000002360 preparation method Methods 0.000 title claims abstract description 21
- 229910052814 silicon oxide Inorganic materials 0.000 title claims abstract description 11
- 239000004964 aerogel Substances 0.000 title claims abstract description 9
- 239000004965 Silica aerogel Substances 0.000 claims abstract description 100
- 239000002245 particle Substances 0.000 claims abstract description 41
- 238000002310 reflectometry Methods 0.000 claims abstract description 36
- 230000003287 optical effect Effects 0.000 claims abstract description 17
- 230000005855 radiation Effects 0.000 claims abstract description 11
- 238000005057 refrigeration Methods 0.000 claims abstract description 11
- 238000000034 method Methods 0.000 claims abstract description 9
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 8
- 235000012239 silicon dioxide Nutrition 0.000 claims abstract description 7
- 239000000203 mixture Substances 0.000 claims abstract description 5
- 229920003217 poly(methylsilsesquioxane) Polymers 0.000 claims abstract description 4
- 239000002243 precursor Substances 0.000 claims description 49
- 238000006068 polycondensation reaction Methods 0.000 claims description 30
- 239000000741 silica gel Substances 0.000 claims description 26
- 229910002027 silica gel Inorganic materials 0.000 claims description 26
- 239000002904 solvent Substances 0.000 claims description 25
- 238000003756 stirring Methods 0.000 claims description 25
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 23
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims description 22
- 125000002496 methyl group Chemical group [H]C([H])([H])* 0.000 claims description 22
- BFXIKLCIZHOAAZ-UHFFFAOYSA-N methyltrimethoxysilane Chemical compound CO[Si](C)(OC)OC BFXIKLCIZHOAAZ-UHFFFAOYSA-N 0.000 claims description 21
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 20
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 20
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 18
- 125000005375 organosiloxane group Chemical group 0.000 claims description 18
- 238000001035 drying Methods 0.000 claims description 17
- 238000006460 hydrolysis reaction Methods 0.000 claims description 14
- 230000002209 hydrophobic effect Effects 0.000 claims description 13
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 12
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 12
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 12
- 239000004094 surface-active agent Substances 0.000 claims description 12
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 claims description 12
- CPUDPFPXCZDNGI-UHFFFAOYSA-N triethoxy(methyl)silane Chemical compound CCO[Si](C)(OCC)OCC CPUDPFPXCZDNGI-UHFFFAOYSA-N 0.000 claims description 12
- GVGUFUZHNYFZLC-UHFFFAOYSA-N dodecyl benzenesulfonate;sodium Chemical compound [Na].CCCCCCCCCCCCOS(=O)(=O)C1=CC=CC=C1 GVGUFUZHNYFZLC-UHFFFAOYSA-N 0.000 claims description 11
- 238000004519 manufacturing process Methods 0.000 claims description 11
- 229940080264 sodium dodecylbenzenesulfonate Drugs 0.000 claims description 11
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 10
- 229910017604 nitric acid Inorganic materials 0.000 claims description 10
- 239000003054 catalyst Substances 0.000 claims description 9
- WOWHHFRSBJGXCM-UHFFFAOYSA-M cetyltrimethylammonium chloride Chemical compound [Cl-].CCCCCCCCCCCCCCCC[N+](C)(C)C WOWHHFRSBJGXCM-UHFFFAOYSA-M 0.000 claims description 9
- 239000003377 acid catalyst Substances 0.000 claims description 8
- 239000000499 gel Substances 0.000 claims description 8
- 239000011148 porous material Substances 0.000 claims description 8
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 7
- LZZYPRNAOMGNLH-UHFFFAOYSA-M Cetrimonium bromide Chemical compound [Br-].CCCCCCCCCCCCCCCC[N+](C)(C)C LZZYPRNAOMGNLH-UHFFFAOYSA-M 0.000 claims description 7
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 7
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 7
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 7
- 230000001276 controlling effect Effects 0.000 claims description 7
- JJQZDUKDJDQPMQ-UHFFFAOYSA-N dimethoxy(dimethyl)silane Chemical compound CO[Si](C)(C)OC JJQZDUKDJDQPMQ-UHFFFAOYSA-N 0.000 claims description 7
- 239000002585 base Substances 0.000 claims description 6
- 239000004202 carbamide Substances 0.000 claims description 6
- YYLGKUPAFFKGRQ-UHFFFAOYSA-N dimethyldiethoxysilane Chemical compound CCO[Si](C)(C)OCC YYLGKUPAFFKGRQ-UHFFFAOYSA-N 0.000 claims description 6
- KPUWHANPEXNPJT-UHFFFAOYSA-N disiloxane Chemical class [SiH3]O[SiH3] KPUWHANPEXNPJT-UHFFFAOYSA-N 0.000 claims description 6
- 230000001105 regulatory effect Effects 0.000 claims description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 6
- DKGAVHZHDRPRBM-UHFFFAOYSA-N Tert-Butanol Chemical compound CC(C)(C)O DKGAVHZHDRPRBM-UHFFFAOYSA-N 0.000 claims description 5
- 238000005191 phase separation Methods 0.000 claims description 5
- WVDDGKGOMKODPV-ZQBYOMGUSA-N phenyl(114C)methanol Chemical compound O[14CH2]C1=CC=CC=C1 WVDDGKGOMKODPV-ZQBYOMGUSA-N 0.000 claims description 4
- 239000003513 alkali Substances 0.000 claims description 3
- 230000007774 longterm Effects 0.000 claims description 3
- 238000006073 displacement reaction Methods 0.000 claims description 2
- 230000006835 compression Effects 0.000 abstract description 6
- 238000007906 compression Methods 0.000 abstract description 6
- 238000006243 chemical reaction Methods 0.000 abstract description 3
- -1 polymethylsiloxane Polymers 0.000 abstract description 3
- 230000003075 superhydrophobic effect Effects 0.000 abstract 1
- 239000000243 solution Substances 0.000 description 30
- 238000002156 mixing Methods 0.000 description 22
- 239000000463 material Substances 0.000 description 15
- WVDDGKGOMKODPV-UHFFFAOYSA-N Benzyl alcohol Chemical compound OCC1=CC=CC=C1 WVDDGKGOMKODPV-UHFFFAOYSA-N 0.000 description 6
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000011347 resin Substances 0.000 description 6
- 229920005989 resin Polymers 0.000 description 6
- 239000011248 coating agent Substances 0.000 description 5
- 238000000576 coating method Methods 0.000 description 5
- 238000009826 distribution Methods 0.000 description 5
- 230000007062 hydrolysis Effects 0.000 description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 description 4
- 238000002835 absorbance Methods 0.000 description 3
- 229910052782 aluminium Inorganic materials 0.000 description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 3
- JEGUKCSWCFPDGT-UHFFFAOYSA-N h2o hydrate Chemical compound O.O JEGUKCSWCFPDGT-UHFFFAOYSA-N 0.000 description 3
- 239000004408 titanium dioxide Substances 0.000 description 3
- 238000002834 transmittance Methods 0.000 description 3
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 description 2
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 2
- 238000000149 argon plasma sintering Methods 0.000 description 2
- 239000012237 artificial material Substances 0.000 description 2
- ZFSFDELZPURLKD-UHFFFAOYSA-N azanium;hydroxide;hydrate Chemical compound N.O.O ZFSFDELZPURLKD-UHFFFAOYSA-N 0.000 description 2
- 235000019445 benzyl alcohol Nutrition 0.000 description 2
- JYYOBHFYCIDXHH-UHFFFAOYSA-N carbonic acid;hydrate Chemical compound O.OC(O)=O JYYOBHFYCIDXHH-UHFFFAOYSA-N 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000011246 composite particle Substances 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000007888 film coating Substances 0.000 description 2
- 238000009501 film coating Methods 0.000 description 2
- 235000019253 formic acid Nutrition 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 239000000017 hydrogel Substances 0.000 description 2
- 238000001000 micrograph Methods 0.000 description 2
- 239000002105 nanoparticle Substances 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000011084 recovery Methods 0.000 description 2
- 229910052709 silver Inorganic materials 0.000 description 2
- 239000004332 silver Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 1
- 238000003917 TEM image Methods 0.000 description 1
- 229910010413 TiO 2 Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000010924 continuous production Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 229910052809 inorganic oxide Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 239000011022 opal Substances 0.000 description 1
- 230000005693 optoelectronics Effects 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 150000001282 organosilanes Chemical class 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 238000010298 pulverizing process Methods 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 238000000985 reflectance spectrum Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000001878 scanning electron micrograph Methods 0.000 description 1
- 238000010008 shearing Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000002210 supercritical carbon dioxide drying Methods 0.000 description 1
- 238000002411 thermogravimetry Methods 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 239000007762 w/o emulsion Substances 0.000 description 1
Classifications
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- 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
- C01P2002/00—Crystal-structural characteristics
- C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
- C01P2002/84—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by UV- or VIS- data
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/80—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70
- C01P2002/88—Crystal-structural characteristics defined by measured data other than those specified in group C01P2002/70 by thermal analysis data, e.g. TGA, DTA, DSC
-
- 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
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- 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
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/50—Agglomerated particles
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/51—Particles with a specific particle size distribution
-
- 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
- C01P2006/10—Solid density
-
- 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
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- 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
- C01P2006/14—Pore volume
-
- 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
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E10/00—Energy generation through renewable energy sources
- Y02E10/50—Photovoltaic [PV] energy
- Y02E10/52—PV systems with concentrators
Abstract
The invention discloses a super-white silicon oxide aerogel, a preparation method and application thereof. The super-white silica aerogel is formed by mutually connecting silica particles to form a three-dimensional porous network structure, the particle size of the silica particles is 100-3000 nm, the power weighted average reflectivity of the super-white silica aerogel for sunlight with the wavelength of 250-2500 nm is 98-99.5%, and the average reflectivity for visible light with the wavelength of 380-780 nm is 98.5-99.9%. The composition of the silicon oxide particles comprises silicon dioxide, polymethylsilsesquioxane, polymethylsiloxane and the like. The super-white silica aerogel has excellent mechanical properties, can be elastically recovered after compression or shear deformation, and has super-hydrophobic properties; meanwhile, the preparation process is simple, the reaction condition is mild, and the method has a huge application prospect in the fields of radiation refrigeration, laser display, solar cell reflecting plates, optical instruments and the like.
Description
Technical Field
The invention relates to a preparation method of silica aerogel, in particular to ultra-white silica aerogel and a preparation method and application thereof, and belongs to the technical field of nano optical materials.
Background
Metamaterial refers to an artificial material having an artificial structure as a basic functional unit capable of realizing supernormal physical properties that natural materials do not possess. In the past decade, a series of novel artificial material systems with singular characteristics have been developed, which are highly valued in all countries of the world, and are expected to produce subversion technologies in various fields. They possess specific properties such as having sound, light, electricity change their usual properties, which is not possible with conventional materials. The peculiar nature of metamaterials derives from their precise geometry and size. Photon metamaterials are man-made nanostructure-containing materials, the special structure imparting specific optical properties thereto (patent: methods of producing metamaterials and metamaterials produced thereby, 2012800281983). Their structure is obtained from at least two different materials. The structure of the material is typically periodic and the period is comparable to or less than the wavelength of light.
The super white material has great application prospect in the fields of radiation refrigeration, light Emitting Diode (LED) display, solar cell back reflecting plate, optical instrument and the like. The device with the highest reflectivity is a distributed bragg reflector (patent CNCN1732604a, a distributed bragg reflector for an optoelectronic device) at present, which is formed by alternately and periodically stacking films with different refractive indexes, and when light passes through the films with different refractive indexes, light reflected by each layer interferes due to the change of a phase angle and then is combined with each other, so that strong reflected light is obtained. However, distributed Bragg reflectors can only strongly reflect light in a range of wavelengths, the reflectivity and reflection bandwidth being limited by the refractive index contrast between the stacked materials, which are typically chosen to be titanium dioxide (n 2.6) and silicon dioxide (n 1.5), with bandwidths limited to within 200 nm.
The manufacturing method of the broadband high-reflectivity material is various, a metal film is the most common broadband reflecting layer, patent CN211180278U discloses a high-reflectivity film structure, PET is taken as a base material, a resin layer is solidified on the top end face, a plurality of reflecting cavities distributed in a stacking structure are pressed on the resin layer, a metal film layer is evaporated or sputtered on the space between the two adjacent reflecting cavities matched with the top end of the resin layer and the inner side wall of each reflecting cavity, and the broadband high-reflectivity is achieved by utilizing the microstructure of the cavities and the reflection of metal. Patent CN111628716a discloses a high-reflection film for an environment-friendly photovoltaic glass back plate, which uses a mirror aluminum foil layer as a main reflection layer to reflect sunlight onto the photovoltaic glass back plate so as to improve the power generation efficiency of a photovoltaic panel assembly. Although metals such as aluminum and silver reflect light in a broad band, the absorbance of the metal reflective layer does not exceed 95% due to the intrinsic absorbance of the metal (aluminum: 15%, silver: 5%). Some wide band gap inorganic oxides have low absorbance and are widely used in reflective layers, for example, patent CN110256888A discloses a high reflectivity diffuse reflective coating, a method for preparing the same and a reflective device, and two are disclosedTitanium oxide, silicon dioxide and barium sulfate particles are dispersed in the aqueous resin, and the large difference of the silicon dioxide and the titanium dioxide in refractive index can lead the composite particles to diffuse reflect incident light, and the composite particles can also fill gaps of the barium sulfate, thereby further improving the reflection effect of the diffuse reflection coating. Patent CN112745712A discloses a scratch-coatable light high-efficiency radiation refrigeration coating, a preparation method and application thereof, wherein the preparation method is to mix reflective pigment, resin binder, organic solvent and auxiliary agent, and then to scratch-coat and cure the coating, wherein the reflectance of the coating in the wave band of 300-2500 nm is not lower than 94%. However, the monodisperse reflective particles cannot be used alone and must be bonded with a resin. TiO (titanium dioxide) 2 The low electron band gap (3.2 eV) of (E) can absorb ultraviolet rays in sunlight, and the ultraviolet rays are used as TiO 2 The solar reflectance of the material as a reflective medium is lower than 95%. Porous structures have also been explored to increase solar reflectance, utilizing the difference in refractive index of air in the solid framework and pores to cause scattering to reflect sunlight. Patent CN112375418A discloses a preparation method of a multi-stage porous radiation refrigeration film coating, which takes a high internal phase water-in-oil emulsion as a template, dissolves organosilane and a high polymer prepolymer or monomer in an oil phase, forms an organic-inorganic composite skeleton through heating polymerization, and is dried to obtain the multi-stage porous radiation refrigeration film coating. However, such emulsion templates are not easily controlled, the scattering of the backbone particles is insufficient, and their reflectivity is 98% or less.
Silicon oxide is an excellent optical material, has a forbidden bandwidth of up to 9eV, does not absorb light rays in a solar wave band, and is widely applied to various optical instruments. In 1995, the Vasily and Astritov team proposed opals (ordered aggregated SiO 2 Ball composition) is an optical metamaterial in the visible region. These ordered silica spheres result in the interference and diffraction of light producing a color shift as light passes through the microstructure of the opal, and the diffraction condition for a particular color is satisfied when the distance between 2 successive layers is approximately equal to the wavelength of that color divided by the refractive index of the sphere. The diffraction wavelength is proportional to the sphere size, and the distance between the planes of regular packing of spheres is about half the wavelength of visible light. For example, the red color is produced by a sphere of about 250nm in diameter, whichHis color is diffracted by smaller spheres, which can be reduced to 140nm in diameter. However, the opals have uniform particle sizes, and can reflect only light rays with specific wavelengths, but cannot achieve broadband high reflection. Aerogel, which is a typical porous material, has a high porosity (80-99.8%), and the difference in refractive index between the solid framework and the air in the pores can scatter light. In addition, the skeleton density, the particle size and the pore size of the aerogel can be regulated and controlled in the aerogel preparation process of sol-gel to enhance the light scattering, so that the silica aerogel is an ideal sunlight scattering material. However, silica aerogel particles are typically small in size (< 30 nm), have limited ability to scatter sunlight, exhibit a pale blue color, and have low reflectivity. And the silica aerogel has fragile skeleton, low strength, easy pulverization and difficult compression resilience (the silica aerogel prepared by the patent CN109592689A is powder without compression and shearing elasticity). Therefore, the preparation of the broadband high-reflectivity high-elasticity ultra-white silica aerogel has important significance.
Disclosure of Invention
The invention mainly aims to provide an ultra-white silica aerogel, a preparation method and application thereof, and solves the technical problem that the reflectivity of the silica aerogel is low 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 super-white silica aerogel, which is formed by mutually connecting silica particles to form a three-dimensional porous network structure, wherein the particle size of the silica particles is 100-3000 nm, the power weighted average reflectivity of the super-white silica aerogel for sunlight with the wavelength of 250-2500 nm is 98-99.5%, and the average reflectivity for visible light with the wavelength of 380-780 nm is 98.5-99.9%; the super-white silica aerogel can recover elasticity after being compressed by 50% to deform or bend by 3mm, the hydrophobic angle of the super-white silica aerogel is 150-160 degrees, and the composition of the silica particles comprises any one or more than two of silicon dioxide, polymethylsilsesquioxane and polymethylsiloxane.
The embodiment of the invention also provides a preparation method of the ultra-white silica aerogel, which comprises the following steps:
1) Dissolving methyl-containing organosiloxane precursor in a solvent, optionally adding or not adding a surfactant, and uniformly stirring to form a precursor solution;
2) Adding an acid catalyst into the precursor solution obtained in the step 1) to carry out hydrolysis reaction, and then adding an alkali catalyst to carry out polycondensation reaction to obtain the ultra-white silica gel;
3) And (3) performing solvent replacement and normal-pressure drying treatment on the ultrawhite silica gel obtained in the step (2) to obtain the ultrawhite silica aerogel.
The embodiment of the invention also provides the ultra-white silica aerogel prepared by the preparation method.
The embodiment of the invention also provides application of the ultra-white silicon oxide aerogel in the fields of radiation refrigeration, laser display, laser protection, solar cell reflecting plates or optical instruments and the like.
Compared with the prior art, the invention has the beneficial effects that:
the ultra-white silica aerogel provided by the invention takes methyl-containing organic siloxane as a precursor, and the gel phase separation degree is accurately controlled by regulating and controlling the proportion of the methyl-containing organic siloxane and the content of the solvent and the surfactant to obtain silica aerogel blocks with large-particle-size nano particles and wide particle-size distribution, so that the controllable preparation of the particle diameter is realized, the preparation process is simple, and the reaction condition is mild; the prepared ultra-white silica aerogel has high reflectivity in a sunlight wave band (250-2500 nm); the material has good mechanical property, good flexibility and excellent superhydrophobicity, can be bent and folded, can be compressed for 50% rebound, and can bear loads such as impact; has great application prospect in the fields of radiation refrigeration, laser display, solar cell reflecting plates, optical instruments and the like.
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 graph showing the desorption of nitrogen from the ultra-white silica aerogel obtained in example 1 of the present invention;
FIG. 2 is a scanning electron microscope image of the ultrawhite silica aerogel obtained in example 1 of the present invention;
FIG. 3 is a transmission electron microscope image of the ultrawhite silica aerogel obtained in example 1 of the present invention;
FIG. 4 is a graph showing the particle size distribution of the ultrawhite silica aerogel obtained in example 1 of the present invention;
FIG. 5 is an optical photograph of the ultrawhite silica aerogel obtained in example 1 of the present invention;
FIG. 6 is a compression rebound optical photograph of the ultrawhite silica aerogel obtained in example 1 of the present invention;
FIG. 7 is a stress-strain curve of the ultra-white silica aerogel obtained in example 1 of the present invention;
FIG. 8 is a scanning electron micrograph of the ultrawhite silica aerogel obtained in example 2 of the present invention;
FIG. 9 is a transmission electron micrograph of the ultrawhite silica aerogel obtained in example 2 of the present invention;
FIG. 10 is a graph showing the TG pattern of the ultrawhite silica aerogel obtained in example 2 of the present invention;
FIG. 11 is a reflectance spectrum of the ultrawhite silica aerogel obtained in example 2 of the present invention.
Detailed Description
In view of the defects in the prior art, the inventor of the present invention has long-term research and a great deal of practice, and has proposed the technical scheme of the present invention, which mainly obtains the ultra-white silica aerogel with high reflectivity and low transmittance through the regulation and control of the methyl-containing organosiloxane precursor. Specifically, the size of silica aerogel particles is usually smaller (< 30 nm), the light scattering capacity is limited, the reflectivity is low, the gel phase separation degree is precisely controlled by regulating and controlling the proportion of methyl-containing organosilicon, the content of solvent and surfactant, and the silica aerogel block with large particle size and wide particle size distribution is obtained.
According to the super-white silica aerogel provided by the embodiment of the invention, silica particles are mutually connected to form a three-dimensional porous network structure, the particle size of the silica particles is 100-3000 nm, the power weighted average reflectivity of the super-white silica aerogel to sunlight (wavelength of 250-2500 nm) is 98-99.5%, and the average reflectivity to visible light (wavelength of 380-780 nm) is 98.5-99.9%. The super-white silica aerogel can recover elasticity after being compressed by 50% to deform or bend by 3mm, has excellent super-hydrophobicity and has a hydrophobic angle of 150-160 DEG, and the composition of the silica particles comprises any one or a combination of more than two of silicon dioxide, polymethylsilsesquioxane and polymethylsiloxane, but is not limited to the above.
In some embodiments, the silica aerogel has a particle size of 100 to 3000nm. The large-size particle size obtained by the invention can reflect 250-2500 nm light more efficiently.
In some embodiments, the three-dimensional porous network structure comprises mesopores with a pore size of 2-50 nm and macropores with a pore size of 50 nm-50 μm.
In some embodiments, the morphology of the silica particles of the ultrawhite silica aerogel includes any one or a combination of two or more of spheres, ellipsoids, irregularities, and the like, but is not limited thereto.
In some embodiments, the super white silica aerogel has a density of 50 to 500mg/cm 3 Preferably 80 to 200mg/cm 3 。
Further, the specific surface area of the ultra-white silica aerogel is 0.1-400 m 2 Preferably 2 to 100m 2 /g。
Further, the pore volume of the ultra-white silica aerogel is 1-10 cm 3 Preferably 3 to 6cm 3 /g。
Further, the porosity of the ultra-white silica aerogel is 50 to 99%, preferably 75 to 95%.
In some embodiments, the ultra-white silica aerogel has a long-term use temperature of above 300 ℃.
In conclusion, the ultra-white silica aerogel has high reflectivity, controllable density, excellent thermal stability and ultra-hydrophobicity in the wave band of 250-2500 nm. Meanwhile, the composite material has good mechanical properties, can compress and shear rebound, and can bear loads such as impact and the like. The ultra-white silica aerogel also has good flexibility and can be bent and folded.
The preparation method of the super white silica aerogel provided by one aspect of the embodiment of the invention mainly comprises the following steps: the method is characterized in that methyl-containing organic siloxane is used as a precursor, and the gel phase separation degree is accurately controlled by regulating and controlling the proportion of the methyl-containing organic siloxane and the content of a solvent and a surfactant to obtain silica aerogel blocks with large particle size nano particles and wide particle size distribution, so that the controllable preparation of the particle diameter is realized; the organic siloxane precursor is hydrolyzed and polycondensed to form gel under the condition of a catalyst, and the ultra-white silica aerogel is obtained through the steps of solvent replacement and drying.
In some embodiments, the method of preparation essentially comprises the steps of:
1) Dissolving methyl-containing organosiloxane precursor in a solvent according to a certain proportion, optionally adding or not adding a surfactant, and uniformly stirring to form a precursor solution;
2) Adding an acid catalyst into the precursor solution obtained in the step 1) to carry out hydrolysis reaction, then adding an alkali catalyst to carry out polycondensation reaction, and separating to obtain the ultra-white silica gel;
3) And (3) performing solvent replacement and normal-pressure drying treatment on the ultrawhite silica gel obtained in the step (2) to obtain the ultrawhite silica aerogel.
In some embodiments, in step 1), the methyl-containing organosiloxane precursor includes any one or a combination of two or more of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, and the like, and is not limited thereto.
Further, the solvent includes any one or a combination of two or more of water, ethanol, benzyl alcohol, N-Dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and the like, and is not limited thereto.
Further, the molar ratio of the solvent to the methyl-containing organosiloxane precursor was 10 -1 About 50:1, preferably about 1 to 5:1.
Further, the surfactant includes any one or a combination of two or more of cetyl trimethylammonium bromide (CTAB), cetyl trimethylammonium chloride (CTAC), sodium Dodecyl Benzene Sulfonate (SDBS), and the like, and is not limited thereto.
Further, the molar ratio of the surfactant to the methyl-containing organosiloxane precursor is from 0 to 0.1:1, preferably from 0 to 0.01:1.
In some embodiments, in step 2), the acid catalyst includes any one or a combination of two or more of hydrochloric acid, nitric acid, sulfuric acid, and the like, and is not limited thereto.
Further, the molar ratio of the acid catalyst to the methyl-containing organosiloxane precursor is 10 -2 ～10 -5 1:1, preferably 10 -3 ～10 -4 ∶1。
Further, the base catalyst includes any one or a combination of two or more of ammonia, urea, triethylamine, tetramethylammonium hydroxide, sodium carbonate, and the like, and is not limited thereto.
Further, the molar ratio of the base catalyst to the methyl-containing organosiloxane precursor is 10 -1 ～10 -4 1:1, preferably 10 -2 ～10 -3 ∶1。
In some embodiments, in step 2), the hydrolysis reaction is carried out for a period of time ranging from 0.1 to 24 hours, preferably from 0.5 to 2 hours, and the hydrolysis reaction temperature is from 10 to 60 ℃, preferably from 20 to 40 ℃.
Further, the polycondensation reaction time is 48 to 96 hours, preferably 48 to 72 hours, and the polycondensation reaction temperature is 60 to 120 ℃, preferably 80 to 100 ℃.
In some embodiments, in step 3), the displacement solvent includes any one or a combination of two or more of water, ethanol, DMSO, t-butanol, methanol, and the like, and is not limited thereto.
Further, the temperature of the solvent substitution is 20 to 60 ℃, preferably 30 to 60 ℃.
Further, the number of solvent substitutions is 0 to 6.
In some embodiments, in step 3), the temperature of the normal pressure drying treatment is 30-120 ℃, the time is not required, and the drying is carried out until the solvent is completely removed.
In conclusion, the preparation process of the ultra-white silica aerogel provided by the invention is simple, mild in reaction condition, easy to operate, low in energy consumption, low in cost, green and pollution-free, and can realize large-scale continuous production.
The embodiment of the invention also provides a huge application prospect of the super white silica aerogel in the fields of radiation refrigeration, laser display, laser protection, solar cell reflecting plates, optical instruments and the like.
As one of the preferable schemes, the application of the ultra-white silica aerogel specifically comprises
1) The ultra-white silica aerogel has high solar reflectance and low transmittance, and can be applied to radiation refrigeration under normal-temperature to high-temperature environments.
2) The high reflectivity of the ultra-white silica aerogel can be applied to one or more application fields in the fields of laser protection, solar sails, optical instruments and the like, but is not limited to the application fields.
By means of the technical scheme, the ultra-white silicon oxide aerogel provided by the invention has high reflectivity, low light transmittance and low density, and has a huge application prospect in the fields of radiation refrigeration, laser protection, solar sails, optical instruments and the like.
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. It should be noted that the examples described below are intended to facilitate the understanding of the present invention and are not intended to limit the present invention in any way. 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) Mixing and stirring methyltrimethoxysilane (MTMS), dimethyldimethoxysilane (DMDMS), hexadecyltrimethyl ammonium chloride and water to form a precursor solution;
(2) Adding hydrochloric acid into the precursor solution in the step (1), mixing and stirring for 0.1 hour at 60 ℃ to hydrolyze, and then adding ammonia water to perform polycondensation reaction, wherein the polycondensation temperature is 60 ℃ and the time is 72 hours, so as to obtain the ultra-white silica gel. Wherein, the mol ratio of MTMS, DMDMS, cetyltrimethylammonium chloride, hydrochloric acid, water and ammonia water is 1:0.1:0.01:0.01:10:0.1.
(3) And (3) replacing the ultra-white silica gel in the step (2) with ethanol for 3 times at 20 ℃ and then drying the gel at 30 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The nitrogen adsorption and desorption curves of the ultra-white silica aerogel obtained in this example are shown in fig. 1, the sem structure is shown in fig. 2, the tem image is shown in fig. 3, the particle size distribution is shown in fig. 4, the optical photograph is shown in fig. 5, the compression elastic recovery optical photograph is shown in fig. 6, and the stress strain curve is shown in fig. 7. The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 2
(1) Mixing and stirring methyltrimethoxysilane, cetyltrimethylammonium chloride and water to form a precursor solution;
(2) Adding hydrochloric acid into the precursor solution in the step (1), mixing and stirring for 24 hours at 10 ℃ to hydrolyze, and then adding ammonia water to perform polycondensation reaction, wherein the polycondensation temperature is 90 ℃ and the time is 48 hours, thus obtaining the ultra-white silica gel. Wherein the mole ratio of MTMS, cetyl trimethyl ammonium chloride, hydrochloric acid, water and ammonia water is 1:0.001:10 -5 ∶4∶10 -4 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with tertiary butanol for 6 times at 20 ℃, and then drying at 30 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The SEM structure of the ultra-white silica aerogel obtained in this example is shown in fig. 8, the tem image is shown in fig. 9, the thermogravimetric analysis image is shown in fig. 10, and the reflectivity is shown in fig. 11. The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 3
(1) Mixing and stirring methyltriethoxysilane, hexadecyl trimethyl ammonium bromide and ethanol to form a precursor solution;
(2) Adding sulfuric acid aqueous solution into the precursor solution in the step (1), mixing and stirring for 3 hours at 10 ℃, adding urea for polycondensation reaction after hydrolysis, wherein the polycondensation temperature is 60 ℃ and the time is 72 hours, and obtaining the ultra-white silica gel. Wherein the mol ratio of methyltriethoxysilane, cetyltrimethylammonium bromide, sulfuric acid, ethanol, water and urea is 1:10 -5 ∶10 -2 ∶0.1∶3∶10 -4 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with tertiary butanol at 20 ℃ for 3 times, and then performing normal-pressure drying at 40 ℃ to obtain the ultra-white silica aerogel.
The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 4
(1) Mixing and stirring methyltriethoxysilane, hexadecyl trimethyl ammonium bromide and ethanol to form a precursor solution;
(2) Adding sulfuric acid aqueous solution into the precursor solution in the step (1), mixing and stirring for 3 hours at 10 ℃, adding urea for polycondensation reaction after hydrolysis, wherein the polycondensation temperature is 60 ℃ and the time is 72 hours, and obtaining the ultra-white silica gel. Wherein the mol ratio of methyltriethoxysilane, cetyltrimethylammonium bromide, sulfuric acid, ethanol, water and urea is 1:0.01:10 -4 ∶4∶4∶10 -3 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with ethanol for 6 times at 20 ℃, and drying at 30 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 5
(1) Mixing and stirring methyltrimethoxysilane, methyltriethoxysilane, sodium dodecyl benzene sulfonate and benzyl alcohol to form a precursor solution;
(2) Adding aqueous solution of nitric acid into the precursor solution in the step (1), mixing and stirring for 1 hour at 60 ℃, adding triethylamine to carry out polycondensation reaction, wherein the polycondensation temperature is 60 ℃ and the time is 72 hours, and obtaining the ultra-white silica gel. Wherein the mol ratio of methyltrimethoxysilane, methyltriethoxysilane, sodium dodecyl benzene sulfonate, benzyl alcohol, nitric acid, water and triethylamine is 1:1:10 -3 ∶5∶10 -2 ∶6∶10 -1 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with DMSO at 30 ℃ for 6 times, and drying at 120 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 6
(1) Mixing and stirring methyltrimethoxysilane, methyltriethoxysilane, sodium dodecyl benzene sulfonate and benzyl alcohol to form a precursor solution;
(2) Adding aqueous solution of nitric acid into the precursor solution in the step (1), mixing and stirring for 1 hour at 40 ℃, adding triethylamine to carry out polycondensation reaction, wherein the polycondensation temperature is 40 ℃ and the time is 48 hours, and obtaining the ultra-white silica gel. Wherein the molar ratio of methyltrimethoxysilane, methyltriethoxysilane, sodium dodecyl benzene sulfonate, benzyl alcohol, nitric acid, water and triethylamine is 1:1:0.01:4:10 -5 ∶6∶10 -4 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with DMSO at 60 ℃ for 2 times, and drying at 120 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 7
(1) Mixing and stirring methyltrimethoxysilane, dimethyldimethoxysilane, sodium dodecyl benzene sulfonate and DMF to form a precursor solution;
(2) Adding aqueous solution of nitric acid into the precursor solution in the step (1), mixing and stirring for 1 hour at 40 ℃, adding tetramethylammonium hydroxide for polycondensation reaction after hydrolysis, wherein the polycondensation temperature is 100 ℃ and the time is 48 hours, and obtaining the ultra-white silica gel. Wherein the molar ratio of methyltrimethoxysilane, methyltriethoxysilane, sodium dodecyl benzene sulfonate, DMF, nitric acid, water and tetramethylammonium hydroxide is 1:1:0.005:4:10 -5 ∶6∶10 -4 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with methanol for 2 times at 30 ℃, and drying at 40 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 8
(1) Mixing and stirring methyltrimethoxysilane, dimethyldimethoxysilane, sodium dodecyl benzene sulfonate and DMF to form a precursor solution;
(2) Adding aqueous solution of nitric acid into the precursor solution in the step (1), mixing and stirring for 1 hour at 40 ℃, adding tetramethylammonium hydroxide for polycondensation reaction, wherein the polycondensation temperature is 120 ℃, and the time is 48 hours, so as to obtain the ultra-white silica gel. Wherein the molar ratio of methyltrimethoxysilane, methyltriethoxysilane, sodium dodecyl benzene sulfonate, DMF, nitric acid, water and tetramethylammonium hydroxide is 1:1:0.004:4:10 -5 ∶6∶10 -4 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with methanol for 2 times at 30 ℃, and drying at 40 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 9
(1) Mixing and stirring methyltrimethoxysilane, dimethyldiethoxysilane and DMSO to form a precursor solution;
(2) Adding aqueous hydrochloric acid solution into the precursor solution in the step (1), mixing and stirring for 1 hour at 30 ℃, adding sodium carbonate for polycondensation reaction after hydrolysis, wherein the polycondensation temperature is 80 ℃ and the time is 96 hours, and obtaining the ultra-white silica gel. Wherein the mol ratio of methyltrimethoxysilane, dimethyldiethoxysilane, DMSO, hydrochloric acid, water and sodium carbonate is 1:1:5:10 -3 ∶3∶10 -2 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with water at 30 ℃ for 6 times, and then drying at 60 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
Example 10
(1) Mixing and stirring methyltrimethoxysilane, dimethyldiethoxysilane and DMSO to form a precursor solution;
(2) Adding aqueous hydrochloric acid solution into the precursor solution in the step (1), mixing and stirring for 1 hour at 30 ℃, adding sodium carbonate for polycondensation reaction after hydrolysis, wherein the polycondensation temperature is 80 ℃ and the time is 96 hours, and obtaining the ultra-white silica gel. Wherein the mol ratio of methyltrimethoxysilane, dimethyldiethoxysilane, DMSO, hydrochloric acid, water and sodium carbonate is 1:1:5:10 -5 ∶3∶10 -4 。
(3) And (3) replacing the ultra-white silica gel in the step (2) with water at 30 ℃ for 6 times, and then drying at 60 ℃ under normal pressure to obtain the ultra-white silica aerogel.
The physical parameters of the ultra-white silica aerogel obtained in this example, such as average particle diameter, specific surface area, reflectivity, and hydrophobic angle, are shown in table 1.
TABLE 1 Structure and Performance parameters of the ultrawhite silica aerogels obtained in examples 1-12
Comparative example 1
(1) Mixing MTMS, hexadecyl trimethyl ammonium chloride and water, stirring to form a precursor solution, adding formic acid, mixing and stirring at 60 ℃ for 24 hours, hydrolyzing, and adding ammonia water for polycondensation reaction. Wherein the mole ratio of MTMS, cetyl trimethyl ammonium chloride, formic acid, water and ammonia water is 1:0.1:10 -1 ∶100∶10 -1 。
(2) And (3) hermetically storing the precursor solution in the step (1) in an oven at 60 ℃ for 72 hours to obtain the hydrogel.
(3) And (3) replacing the scatterer hydrogel in the step (2) with ethanol for 6 times at 30 ℃, and obtaining the silica aerogel by adopting a supercritical carbon dioxide drying process, wherein the particle size is only 2-50 nm.
As can be seen from comparison, in the embodiment 1 of the invention, the gel phase separation degree is accurately controlled by regulating and controlling the proportion of methyl-containing organosilicon, the content of solvent and surfactant, the particle size of the obtained ultra-white silica aerogel is 200nm, which is far larger than that (2-50 nm) of the silica aerogel in the comparative example 1, so that the ultra-white silica aerogel can have strong reflection effect on the whole sunlight spectrum and visible light, and the reflectivity is higher than 98%. Whereas the silica aerogel of comparative example 1 had a small particle size and was only permeable to light. In addition, the silica aerogel of large-size particles had strong neck-in connection and good compression and shear recovery properties, while the silica aerogel of comparative example 1 was brittle.
In addition, the inventors also prepared a series of ultra-white silica aerogels by the method of examples 1-10, using other materials and process conditions as set forth herein. It has been found that these ultra-white silica aerogels also have the excellent properties described in this 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 (11)
1. The preparation method of the ultra-white silica aerogel is characterized by comprising the following steps:
1) Dissolving methyl-containing organosiloxane precursor in a solvent, optionally adding or not adding a surfactant, and uniformly stirring to form a precursor solution; the methyl-containing organosiloxane precursor comprises any one or more than two of methyltrimethoxysilane, methyltriethoxysilane, dimethyldimethoxysilane and dimethyldiethoxysilane; the solvent comprises any one or more than two of water, ethanol, benzyl alcohol, N-dimethylformamide and dimethyl sulfoxide; the molar ratio of the solvent to the methyl-containing organosiloxane precursor is 0.1-10: 1, a step of; the surfactant comprises any one or more than two of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride and sodium dodecyl benzene sulfonate; the molar ratio of the surfactant to the methyl-containing organosiloxane precursor is 0-0.01: 1, a step of;
2) Adding an acid catalyst into the precursor solution obtained in the step 1) to carry out hydrolysis reaction, and then adding an alkali catalyst to carry out polycondensation reaction to obtain the ultra-white silica gel; the acid catalyst comprises any one or the combination of more than two of hydrochloric acid, nitric acid and sulfuric acid; the molar ratio of the acid catalyst to the methyl-containing organosiloxane precursor was 10 -2 ~10 -5 :1, a step of; the base catalyst comprises any one or more than two of ammonia water, urea, triethylamine, tetramethylammonium hydroxide and sodium carbonate; the molar ratio of the base catalyst to the organosiloxane precursor was 10 -1 ~10 -4 ：1；
3) Performing solvent replacement and normal-pressure drying treatment on the ultrawhite silica gel obtained in the step 2) to obtain ultrawhite silica aerogel;
the method comprises the steps of controlling the particle size of the generated silicon oxide particles to be 100-1300 nm by accurately controlling the gel phase separation degree through regulating and controlling the proportion of an organosiloxane precursor containing methyl and the content of a solvent and a surfactant;
the prepared ultra-white silica aerogel is formed by mutually connecting silica particles to form a three-dimensional porous network structure, the particle size of the silica particles is 100-1300 nm, the power weighted average reflectivity of the ultra-white silica aerogel to sunlight with the wavelength of 250-2500 nm is 98-99.5%, and the average reflectivity to visible light with the wavelength of 380-780 nm is 98.5-99.9%; the super-white silica aerogel can be elastically restored after being compressed by 50% to deform or bend by 3mm, the hydrophobic angle of the super-white silica aerogel is 150-160 degrees, and the composition of the silica particles comprises any one or more than two of silicon dioxide, polymethyl silsesquioxane and polymethyl siloxane.
2. The method of manufacturing according to claim 1, characterized in that: the molar ratio of the solvent to the methyl-containing organosiloxane precursor is 1-5: 1.
3. the method of manufacturing according to claim 1, characterized in that: the molar ratio of the acid catalyst to the methyl-containing organosiloxane precursor was 10 -3 ~10 -4 :1, a step of; the molar ratio of the base catalyst to the organosiloxane precursor was 10 -2 ~10 -3 ：1。
4. The method of manufacturing according to claim 1, characterized in that: in the step 2), the time of the hydrolysis reaction is 0.1-24 h, and the temperature of the hydrolysis reaction is 10-60 ℃; the time of the polycondensation reaction is 48-96 hours, and the temperature of the polycondensation reaction is 60-120 ℃.
5. The method of manufacturing according to claim 4, wherein: the time of the hydrolysis reaction is 0.5-2 h, and the temperature of the hydrolysis reaction is 20-40 ℃; the time of the polycondensation reaction is 48-72 h, and the temperature of the polycondensation reaction is 80-100 ℃.
6. The method of manufacturing according to claim 1, characterized in that: in the step 3), the displacement solvent comprises any one or more than two of water, ethanol, DMSO, tertiary butanol and methanol; the temperature of the solvent replacement is 20-60 ℃; the number of solvent replacement times is 0-6.
7. The method of manufacturing according to claim 6, wherein: the temperature of the solvent replacement is 30-60 ℃.
8. The method of manufacturing according to claim 1, characterized in that: in the step 3), the temperature of the normal pressure drying treatment is 30-120 ℃.
9. The method of manufacturing according to claim 1, characterized in that: the three-dimensional porous network structure comprises mesopores with the aperture of 2-50 nm and macropores with the aperture of 50 nm-50 mu m;
the particle size of the silicon oxide particles is 100-500 nm;
the form of the silicon oxide particles comprises any one or more than two of spheres, ellipsoids and irregularities;
the density of the ultra-white silicon oxide aerogel is 50-500 mg/cm 3 ；
The specific surface area of the ultra-white silica aerogel is 0.1-400 m 2 /g；
The pore volume of the ultra-white silica aerogel is 1-10 cm 3 /g；
The porosity of the ultra-white silica aerogel is 50-99%.
10. The method of manufacturing according to claim 1, characterized in that: the long-term use temperature of the ultra-white silica aerogel is above 300 ℃.
11. Use of the ultra-white silica aerogel produced by the production method of any one of claims 1 to 10 in the fields of radiation refrigeration, laser display, laser protection, solar cell reflectors or optical instruments.
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