CN111115644B - High-temperature-resistant silicon dioxide aerogel material - Google Patents
High-temperature-resistant silicon dioxide aerogel material Download PDFInfo
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- CN111115644B CN111115644B CN201910794661.9A CN201910794661A CN111115644B CN 111115644 B CN111115644 B CN 111115644B CN 201910794661 A CN201910794661 A CN 201910794661A CN 111115644 B CN111115644 B CN 111115644B
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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
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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
- C01B33/155—Preparation of hydroorganogels or organogels
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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
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Abstract
The invention relates to the technical field of aerogel materials, in particular to a high-temperature-resistant silicon dioxide aerogel material and a preparation method thereof, and the high-temperature-resistant silicon dioxide aerogel material at least comprises the following preparation raw materials: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water. According to the invention, ethyl orthosilicate and alkoxy silane are used as silicon sources, and alkyl chlorosilane and phosphorus-containing organic siloxane are added in the gel aging stage, so that the silicon dioxide aerogel can keep a porous structure and has a low heat conductivity coefficient, high gel framework strength, proper flexibility and low moisture absorption tendency.
Description
Technical Field
The invention relates to the technical field of aerogel materials, in particular to a high-temperature-resistant silicon dioxide aerogel material and a preparation method thereof.
Background
Aerogel, a special material that maintains the network structure or volume of gel itself by replacing liquid in the gel with gas, is a dried product of hydrogel or organogel, and is mainly divided into inorganic, organic and composite gels, of which most studied is silicon dioxide (SiO)2) An aerogel. As a nano porous solid material with high specific surface area, high porosity, low density, low thermal conductivity and other excellent performances, the nano porous solid material has been successfully applied to the aspects of Cerenkov detectors, super heat insulating materials, catalyst carriers and the like. With the development of the fields of catalysis and thermal insulation, the demand of high-temperature resistant aerogel is more and more urgent. For example, in the treatment of gas emissions or catalytic combustion, certain catalytic reactions are carried out at temperatures above 800 ℃.
The sol-gel method is used for preparing SiO2The main method of the aerogel is to use silicon source materials such as methyl orthosilicate, ethyl orthosilicate, water glass and the like as precursors, catalytically synthesize wet gel by adopting an acid-base two-step method or a one-step method, and then prepare the wet gel by a supercritical drying technology or a non-supercritical drying technology. Compared with the supercritical drying process, the preparation of SiO by drying at normal pressure2The aerogel greatly reduces the cost and the operation danger, the used equipment is simple and can be continuously produced, and the SiO is improved2The possibility of industrial production of the aerogel, but some normal pressure drying methods have long preparation period and the preparation process route needs to be optimized. And volume expansion in the drying process inevitably causes extrusion of holes in the porous material, so that the original porous structure cannot be maintained, and the original performance characteristics of the material are greatly reduced.
Silica aerogel has been favored by a large number of researchers as the material having the best thermal insulation properties so far. However, the silica gel is complex in process and difficult to control in surface modification process, so that the silica aerogel is brittle and fragile, low in strength, not strong enough in compression resistance and the like, and easily loses heat insulation performance, and the application range of the aerogel is greatly limited.
Disclosure of Invention
In order to solve the above problems, a first aspect of the present invention provides a high temperature resistant silica aerogel material, which at least comprises the following preparation raw materials: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
As a preferred technical solution of the present invention, the structural formula of the alkoxysilane is:
wherein R is1、R2Each independently is an alkoxy or alkyl group having 1-2 carbon atoms, R3Is C1-2 alkoxy, R4Is a long chain alkyl group with 8-15 carbon atoms.
As a preferred technical scheme of the invention, the alkoxy silane is selected from one or more of dodecyl (methyl) dimethoxysilane, dodecyl triethoxysilane, tetradecyl triethoxysilane and dodecyl trimethoxysilane.
As a preferable technical scheme of the invention, the phosphorus-containing oxysilane is prepared from vinyl dimethyl ethoxysilane.
As a preferable technical scheme of the invention, the phosphorus-containing oxylsilane is prepared by reacting vinyl dimethyl ethoxysilane with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.
As a preferred technical solution of the present invention, the structural formula of the alkylchlorosilane is:
wherein R ', R ' and R ' are alkyl with 1-4 carbon atoms respectively.
As a preferable technical scheme of the invention, the alkylchlorosilane is selected from one or more of triisobutylchlorosilane, n-butyldimethylchlorosilane, triisopropylchlorosilane, propyldimethylchlorosilane and tert-butyldimethylchlorosilane.
As a preferable technical scheme of the invention, the molar ratio of the ethyl orthosilicate, the alkoxysilane, the phosphorus-containing oxysilane and the alkylchlorosilane is 3: (0.5-2): (0.6-1): 1.
in a preferred embodiment of the present invention, the acidic catalyst is selected from one or more of phosphoric acid, hydrochloric acid, oxalic acid, and sulfuric acid.
In a preferred embodiment of the present invention, the basic catalyst is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, and calcium hydroxide.
As a preferable technical scheme of the invention, the small molecule alkane is selected from one or more of n-hexane, n-heptane and n-octane.
The second aspect of the present invention provides a method for preparing a high temperature resistant silica aerogel, comprising at least the following steps:
(1) preparing silicon dioxide wet gel by using tetraethoxysilane and alkoxy silane as silicon sources;
(2) soaking the silica wet gel in ethanol, phosphorus-containing oxysilane and alkylchlorosilane to obtain an aged wet gel;
(3) soaking the aged wet gel in ethanol and small molecule alkane, and drying to obtain SiO2An aerogel material.
Has the advantages that: the invention provides a high-temperature-resistant silica aerogel, which is prepared by selecting tetraethoxysilane and alkoxy silane as silicon sources and adding phosphorus-containing organic siloxane in a gel aging stage, so that the problems of high temperature resistance, reduced porosity and the like in the preparation process of silica are solved, the original porous structure of the silica aerogel can be maintained, the thermal conductivity coefficient is lower, and meanwhile, the silica aerogel which has higher gel framework strength, proper flexibility and is difficult to absorb moisture is obtained.
Detailed Description
The technical features of the technical solutions provided by the present invention are further clearly and completely described below with reference to the specific embodiments, and the scope of protection is not limited thereto.
The words "preferred", "more preferred", and the like, in the present invention refer to embodiments of the invention that may provide certain benefits, under certain circumstances. However, other embodiments may be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, nor is it intended to exclude other embodiments from the scope of the invention.
When a range of values is disclosed herein, the range is considered to be continuous and includes both the minimum and maximum values of the range, as well as each value between such minimum and maximum values. Further, when a range refers to an integer, each integer between the minimum and maximum values of the range is included. Further, when multiple range-describing features or characteristics are provided, the ranges may be combined. In other words, unless otherwise indicated, all ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range from 1 to 10 should be considered to include any and all subranges between the minimum value of 1 and the maximum value of 10. Exemplary subranges of the range 1 to 10 include, but are not limited to, 1 to 6.1, 3.5 to 7.8, 5.5 to 10, and the like.
In order to solve the above problems, a first aspect of the present invention provides a high temperature resistant silica aerogel material, which at least comprises the following preparation raw materials: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
Alkoxy silane
The structural formula of the alkoxy silane is as follows:
wherein R is1、R2Each independently is an alkoxy or alkyl group having 1-2 carbon atoms, R3Is C1-2 alkoxy, R4Having 8 to 15 carbon atomsA long chain alkyl group.
In some embodiments, the alkoxysilane is selected from one or more combinations of dodecyl (methyl) dimethoxysilane (CAS: 163131-89-3), dodecyl triethoxysilane (CAS: 18536-91-9), tetradecyl triethoxysilane (CAS: 16153-27-8), dodecyl trimethoxysilane (CAS: 3069-21-4).
In a preferred embodiment, the alkoxysilane is dodecyl (methyl) dimethoxysilane.
Silica aerogel is a porous solid material having a network structure of a beaded skeleton, and weak connection between secondary particles of silica causes silica aerogel to have great brittleness, and it is difficult to maintain a block-shaped structure when used. In addition, silica aerogel contains more hydrophilic hydroxyl groups, and is easy to absorb moisture and generate structural change when stored in the air.
The inventor finds that the hydrophobicity of the surface and the inner pores of the silica aerogel can be improved by regulating the type of the silicon source in the gel forming process, namely adding the alkoxy silane as one of the silicon sources, probably because the alkoxy of the alkoxy silane is hydrolyzed to generate hydroxyl under the action of an acid catalyst, the hydroxyl and the hydroxyl in the silica sol are subjected to further dehydration condensation, meanwhile, the hydrolysis product of the alkoxy silane per se is subjected to dehydration condensation, each alkoxy silane molecule at least contains one inactive long-chain alkyl group, the sigma bond in the alkyl group has small polarity, the molecular dipole moment of the alkyl group is zero, and the molecular dipole moment belongs to a non-polar molecule, so that the silicon source is not easy to absorb moisture. In addition, the inventor also found that the flexibility of the silica aerogel is improved to some extent, probably because the Si-OH in each alkoxysilane undergoes dehydration condensation reaction, and the existence of long-chain alkyl in the product may bring about improvement of the flexibility of the aerogel, so that the skeleton is softer. However, in the course of experiments, the inventors have found that when an alkoxysilane having an inactive alkyl group with a larger number of carbon atoms is added, the viscosity of the reaction system becomes large, so that the condensation reaction of the hydrophobic group is insufficient, and the hydrophobic effect is not preferable. And when the alkoxysilane is selected, the structural formula is:
(R1、R2each independently is an alkoxy or alkyl group having 1-2 carbon atoms, R3Is C1-2 alkoxy, R4The carbon number of the long-chain alkyl group is 8-15), the hydrolysis condensation reaction is fast, the prepared aerogel has good hydrophobic property, and probably because the alkoxysilane with the structure can sufficiently participate in the hydrolysis condensation reaction under the condition that the system viscosity is not influenced, and the ethanol generated by hydrolysis can bring hydration, so that the alkoxysilane can sufficiently react with the ethyl orthosilicate in the condensation stage, the internal skeleton of the gel is ensured to have hydrophobic groups, and the aerogel with good hydrophobic property is prepared.
Acidic catalyst
The acidic catalyst of the invention is a substance which has acidity and can play a role of acid catalysis.
In some embodiments, the acidic catalyst is selected from one or more combinations of phosphoric acid, hydrochloric acid, oxalic acid, nitric acid.
In a more preferred embodiment, the acidic catalyst is phosphoric acid.
Basic catalyst
The basic catalyst of the invention is a substance which has alkalinity and can play a role of alkali catalysis.
In some embodiments, the basic catalyst is selected from one or more of ammonia, sodium hydroxide, potassium hydroxide, calcium hydroxide in combination.
In a more preferred embodiment, the basic catalyst is ammonia.
Phosphorus-containing oxysilanes
The phosphorus-containing oxysilane is a novel organosilicon material formed by introducing phosphorus elements into a siloxane main chain or a side group through a chemical reaction.
In a preferred embodiment, the phosphorus-containing oxysilane is prepared from vinyldimethylethoxysilane (CAS: 5356-83-2).
In a more preferred embodiment, the phosphoxysilane is prepared by reacting vinyldimethylethoxysilane with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (CAS: 35948-25-5).
In a more preferred embodiment, the phosphorus-containing oxysilane is prepared by: adding 10.83g of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (0.05mol) into a three-neck flask, adding 10ml of chloroform as a solvent, placing the three-neck flask in an oil bath at 75 ℃ and introducing nitrogen, adding 0.13g of initiator azobisisobutyronitrile after the 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is completely dissolved in the chloroform, beginning to dropwise add 9.3ml of vinyl dimethylethoxysilane (0.05mol), reacting for 20 hours to obtain a light yellow liquid, and removing the solvent through rotary evaporation to obtain the compound.
Alkylchlorosilanes
The structural formula of the alkyl chlorosilane is as follows:
wherein R ', R ' and R ' are alkyl with 1-4 carbon atoms respectively.
In a preferred embodiment, the alkylchlorosilane is selected from one or more combinations of triisobutylchlorosilane (CAS: 13154-25-1), n-butyldimethylchlorosilane (CAS: 1000-50-6), triisopropylchlorosilane (CAS: 13154-24-0), propyldimethylchlorosilane (CAS: 17477-29-1), and tert-butyldimethylchlorosilane (CAS: 18162-48-6).
In a more preferred embodiment, the alkylchlorosilane is triisobutylchlorosilane.
In a more preferred embodiment, the molar ratio of ethyl orthosilicate, alkoxysilane, phosphosilane, alkylchlorosilane is 3: (0.5-2): (0.6-1): 1.
the silica aerogel prepared by the invention can generate the phenomena of combustion and high temperature resistance reduction under the action of high temperature and certain oxygen, which is probably caused by the phenomenon thatThe silicon source used in the invention contains alkoxy silane, and SiO prepared by using the alkoxy silane as a precursor2The aerogel contains more carbon chains, so that residual Si-0R (R represents alkyl) possibly exists on the skeleton, and more Si-C bonds and C-H bonds exist in the network structure, and when the aerogel is subjected to heat radiation generated by inevitable high temperature, flame or other material ignition, under the action of certain temperature and oxygen, hydrophobic SiO2The organic components (Si-OR, Si-R) in the aerogel are pyrolyzed (thermally oxidized) and release combustible volatile components, thereby reducing the high temperature resistance of the silica aerogel.
The inventors have found that SiO can be solved by adding a phosphorus-containing organosiloxane prepared by reacting vinyldimethylethoxysilane and 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide2The inflammability of the aerogel is mainly because in the combustion process, the phosphorus-containing siloxane can be decomposed to generate a non-combustible liquid film of phosphoric acid, and when the aerogel is further combusted, the phosphoric acid can be dehydrated to generate metaphosphoric acid and polymetaphosphoric acid, so that the polymer is dehydrated and carbonized, and a carbon film formed on the surface can isolate air and heat, thereby playing a role of inflaming retarding. And the organosilicon polymer has low surface energy characteristic, so that the organosilicon polymer is easy to migrate to the surface of the carbon layer, a silicon protective layer of carbon can be formed, the carbon layer is protected, and a good effect on flame retardance of the material can be achieved under the synergistic effect of phosphorus and silicon.
Through experiments, the inventor also unexpectedly finds that the addition of the phosphorus-containing siloxane can also improve the strength of a gel network framework and the hydrophobicity of the gel, probably because the phosphorus-containing siloxane generates a Si-OH through hydrolysis, the existence of an organic group benzene ring can bring certain steric hindrance to hinder the self polycondensation reaction, and the phosphorus-containing siloxane is further polycondensed with the Si-OH on the surface of the formed silica hydrogel, so that the phosphorus element with flame retardance, a benzene ring structure and hydrophobic methyl are grafted on the surface of the gel, and the strength and the hydrophobicity of the gel network framework are improved.
In addition, the inventors have found through experiments that when too much phosphorous containing siloxane is added, the strength of the aerogel is too high and cracking is liable to occur. The inventor finds that by regulating the molar ratio of the ethyl orthosilicate, the alkoxy silane and the phosphorus-containing siloxane to be 3: (0.5-2): (0.6-1), the aerogel with better flexibility and strength can be obtained. When too much phosphorus-containing siloxane is added, the aerogel is easy to crack probably because too much benzene rings are introduced, so that the difference between the surface and the internal mechanical strength of the aerogel is larger, the brittleness of the system is larger, and the toughness is reduced. By adjusting the ratio of ethyl orthosilicate, alkoxysilane and phosphorus-containing siloxane, a balance between stiffness and flexibility may be achieved, thereby solving the problem of susceptibility to cracking.
Furthermore, the inventors have found that the resulting aerogel porosity decreases during the gel drying process. The inventor finds that alkylchlorosilanes can allow the porosity of the aerogel to be better controlled and can further improve the hydrophobicity of the aerogel. The porosity of the aerogel is probably reduced because a phosphorus-containing structure with benzene rings in a gel network obtained by hydrolysis and condensation of phosphorus-containing siloxane is an electron-withdrawing group and is mutually attracted with an alkyl group for electron supply in the gel, so that the rebound degree of the gel after the solvent is evaporated is reduced, and the pores of the gel are influenced. The benzene ring on the silicon dioxide cluster obtained by the hydrolysis condensation reaction of the phosphorus-containing siloxane brings certain steric hindrance, so that the condensation reaction between Si and OH on the surface of the gel cluster can be reduced, the network gel can be favorably reacted with alkyl chlorosilane with higher reaction activity more, the reaction efficiency is higher, gel with more hydrophobic groups is formed, and the hydrophobicity of the aerogel is improved; in addition, the gel generated by the reaction has more electron-donating alkyl groups, so that the mutual repulsive acting force in a gel system can be enhanced, the resilience of a condensed skeleton is promoted, the condensed skeleton can be expanded to be almost close to the size of the initial gel, the skeleton is more complete, and the porosity is improved.
However, when more alkylchlorosilane is added, the porosity of the aerogel is reduced, probably because more HCl is generated in the reaction, the pores in the aerogel are damaged, and the pores of the aerogel are easy to collapse and deform, so that the porosity of the aerogel is reduced. The inventor adjusts the mol ratio of the trimethylchlorosilane to the phosphorus-containing siloxane to be 1: (0.6-1), the aerogel structure is not affected, and the hydrophobicity and the porosity are ideal.
Small molecule alkane
The small molecular alkane is open-chain saturated chain hydrocarbon, carbon atoms in molecules are connected through single bonds, other valence bonds are combined with hydrogen, and the number of the carbon atoms is 3-7.
In some embodiments, the small molecule alkane is selected from one or more of n-hexane, n-heptane, and n-octane.
In a more preferred embodiment, the small molecule alkane is n-hexane.
The second aspect of the present invention provides a method for preparing a high temperature resistant silica aerogel, comprising at least the following steps:
(1) preparing silicon dioxide wet gel by using tetraethoxysilane and alkoxy silane as silicon sources;
(2) soaking the silica wet gel in ethanol, phosphorus-containing oxysilane and alkylchlorosilane to obtain an aged wet gel;
(3) soaking the aged wet gel in ethanol and small molecule alkane, and drying to obtain SiO2An aerogel material.
In a preferred embodiment, the method for preparing a refractory silica aerogel at least comprises the following steps:
(1) adding ethanol and deionized water into a silicon source by using tetraethoxysilane and alkoxy silane as the silicon source, and uniformly stirring, wherein the molar ratio of the silicon source to the ethanol to the deionized water is 1: (3-5): (2-3), adding an acidic catalyst, adjusting the pH value to 2-3, stirring for 10-20min, adding an alkaline catalyst, adjusting the pH value to 7-8, stirring, and standing to obtain SiO2Wet gel;
(2) mixing SiO2And (3) placing the wet gel into ethanol, phosphorus-containing oxysilane and alkyl chlorosilane, and soaking for 12-24 hours at 50-60 ℃ to obtain the aged wet gel, wherein the volume ratio of the total volume of the phosphorus-containing oxysilane and the alkyl chlorosilane to the ethanol is 1: (1-3);
(3) placing the aged wet gel into ethanol and n-hexane, and soaking for 5-6 h at 50-60 ℃, wherein the wet gel is prepared by the steps ofIn the method, the volume ratio of ethanol to n-hexane is 1: 5, drying for 5-6 h at 80 ℃ under normal pressure to obtain SiO2An aerogel material.
The inventors have found that when the alkoxysilane is added only during the wet gel preparation stage and the phosphoxysilane and alkylchlorosilane are added during the gel aging stage in the preparation of silica aerogel, the silica aerogel prepared has relatively best performance in all respects.
In the experimental process, the inventor finds that the hydrophobicity and the flexibility of the aerogel prepared by adding the alkoxy silane as a silicon source are ideal. This is probably because the alkoxysilane added at this time can prepare a stable three-dimensional network gel skeleton having more long-chain alkyl groups on the surface and in the internal pores of the aerogel, so that the flexibility and hydrophobic group distribution is not too concentrated, i.e., the local strength is not too low or the local brittleness is not too high, which is beneficial to the improvement of the hydrophobicity and the flexibility.
The inventor also finds that the aerogel prepared by adding the phosphorus-containing oxysilane and the alkylchlorosilane in the aging stage has ideal high-temperature resistance, strength and porosity. The reason for this is probably that phosphoxysilane and alkylchlorosilane are added in the aging stage, and the phosphoxysilane is hydrolyzed and then condensed with Si-OH on the surface of the formed silica hydrogel, so that more flame-retardant phosphorus elements, benzene ring structures and hydrophobic methyl groups can be grafted on the surface of the gel skeleton, the high temperature resistance of the aerogel can be improved, and the strength and hydrophobicity of the gel network skeleton relative to the outer layer can be further improved. And because the surface gel has certain steric hindrance, the reaction of alkyl chlorosilane and network gel is facilitated, so that the gel network can be surrounded by more alkyl groups, the hydrophobicity is improved, the capillary force is reduced, and the subsequent drying treatment is facilitated. Meanwhile, the existence of more electron-donating alkyl groups can weaken the attraction between electron-withdrawing groups in the phosphorus-containing siloxane and surrounding electron-donating groups, and the dried gel can rebound, so that the integrity of the skeleton is kept and the porosity is improved. However, if the phosphoxysilane and alkylchlorosilane are added in the wet gel preparation stage and the alkoxysilane is added in the gel aging stage, the inventors have found that the aerogel prepared at this time has reduced flexibility and is liable to crack. This is probably because the phosphorus-containing oxysilane is added in the preparation stage of the wet gel, benzene ring groups are distributed on the surface and the internal pores of the prepared gel, and the long-chain alkyl groups are more distributed on the surface of the gel skeleton by adding the alkoxysilane in the aging stage, so that the prepared aerogel has larger internal brittleness and lower flexibility. In addition, due to the presence of attractive forces between electron-withdrawing groups and surrounding electron-donating groups in the phosphosiloxane contained in the gel, the gel structure shrinks and microcracks occur upon drying, thereby easily breaking.
The inventors have found that if the alkoxysilane, phosphoxysilane and alkylchlorosilane are added simultaneously during the wet gel preparation stage, the flexibility, strength and porosity of the prepared aerogel are reduced. In the hydrolysis and condensation process of gel formation, as silicon sources are various, on one hand, alkyl groups and benzene ring groups in the silicon sources cannot be relatively uniformly distributed in an aerogel skeleton structure, so that the local strength is too high, and the preparation of aerogel materials with good overall hydrophobic property and mechanical property is not facilitated; on the other hand, the introduction of more hydrophobic groups can leave some sol particles which are not reacted sufficiently and small gel clusters dispersed in the sol particles, so that the aerogel with certain strength and high porosity is difficult to form.
The inventors have found that if alkoxysilane, phosphoxysilane and alkylchlorosilane are added simultaneously during the aging stage, the mechanical strength of the aerogel obtained becomes poor. This is probably because the tetraethoxysilane at the time of the aging stage already forms the basic skeleton of the gel network, and after the alkylchlorosilane, the alkoxysilane and the phosphoxysilane are hydrolyzed, condensation occurs more with the hydroxyl groups on the surface of the formed gel, and alkyl and benzene ring groups are more intensively distributed on the surface of the gel, thereby causing the phenomena of hard outside and brittle inside, and low or too brittle local strength.
The present invention will now be described in detail by way of examples, and the starting materials used are commercially available unless otherwise specified.
Example 1
Embodiment 1 of the present invention provides a high temperature resistant silica aerogel material, which is prepared from at least: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The preparation method of the phosphorus-containing oxysilane comprises the following steps: adding 10.83g of 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (0.05mol) into a three-neck flask, adding 10ml of chloroform as a solvent, placing the three-neck flask in an oil bath at 75 ℃ and introducing nitrogen, adding 0.13g of initiator azobisisobutyronitrile after the 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide is completely dissolved in the chloroform, beginning to dropwise add 9.3ml of vinyl dimethylethoxysilane (0.05mol), reacting for 20 hours to obtain a light yellow liquid, and removing the solvent through rotary evaporation to obtain the compound.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 0.5: 0.6: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material at least comprises the following steps:
(1) adding ethanol and deionized water into a silicon source by using tetraethoxysilane and alkoxy silane as the silicon source, and uniformly stirring, wherein the molar ratio of the silicon source to the ethanol to the deionized water is 1: 4: 2, adding an acidic catalyst, adjusting the pH value to 2-3, stirring for 15min, then adding an alkaline catalyst, adjusting the pH value to 7-8, stirring, and standing to obtain SiO2Wet gel;
(2) mixing SiO2Placing the wet gel in ethanol, phosphorus-containing oxysilane and alkylchlorosilane, and soaking at 55 deg.C for 20 hr to obtain aged wet gel, wherein the total volume of phosphorus-containing oxysilane and alkylchlorosilane and the volume of ethyleneThe volume ratio of the alcohol is 1: 2;
(3) and (2) placing the aged wet gel into ethanol and n-hexane, and soaking for 6h at the temperature of 55 ℃, wherein the volume ratio of the ethanol to the n-hexane is 1: 5, drying for 6 hours at the temperature of 80 ℃ under normal pressure to obtain SiO2An aerogel material.
Example 2
Embodiment 2 of the present invention provides a high temperature resistant silica aerogel material, which is prepared from at least: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 2: 1: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material comprises the same steps as example 1.
Example 3
Embodiment 3 of the present invention provides a high temperature resistant silica aerogel material, which is prepared from at least: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 1: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material comprises the same steps as example 1.
Comparative example 1
Comparative example 1 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxy silane to the phosphorus-containing oxy silane to the alkyl chlorosilane is 5: 1: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material comprises the same steps as example 1.
Comparative example 2
Comparative example 2 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 5: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material comprises the same steps as example 1.
Comparative example 3
Comparative example 3 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 1: 3: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material comprises the same steps as example 1.
Comparative example 4
Comparative example 4 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 1: 0.8: 3.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material comprises the same steps as example 1.
Comparative example 5
Comparative example 5 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 1: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material at least comprises the following steps:
(1) by usingEthyl orthosilicate, phosphorus-containing oxysilane and alkyl chlorosilane are used as silicon sources, ethanol and deionized water are added into the silicon sources, and the mixture is uniformly stirred, wherein the molar ratio of the silicon sources to the ethanol to the deionized water is 1: 4: 2, adding an acidic catalyst, adjusting the pH value to 2-3, stirring for 15min, then adding an alkaline catalyst, adjusting the pH value to 7-8, stirring, and standing to obtain SiO2Wet gel;
(2) mixing SiO2And (3) placing the wet gel into ethanol and alkoxy silane, and soaking for 20h at the temperature of 55 ℃ to obtain an aged wet gel, wherein the volume ratio of alkoxy silane to ethanol is 1: 2;
(3) and (2) placing the aged wet gel into ethanol and n-hexane, and soaking for 6h at the temperature of 55 ℃, wherein the volume ratio of the ethanol to the n-hexane is 1: 5, drying for 6 hours at the temperature of 80 ℃ under normal pressure to obtain SiO2An aerogel material.
Comparative example 6
Comparative example 6 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 1: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material at least comprises the following steps:
(1) with ethyl orthosilicate, alkoxysilane, phosphoxysilane, and alkylchlorosilaneAdding ethanol and deionized water into a silicon source, and uniformly stirring, wherein the molar ratio of the silicon source to the ethanol to the deionized water is 1: 4: 2, adding an acidic catalyst, adjusting the pH value to 2-3, stirring for 15min, then adding an alkaline catalyst, adjusting the pH value to 7-8, stirring, and standing to obtain SiO2Wet gel;
(2) mixing SiO2Soaking the wet gel in ethanol at 55 deg.C for 20 hr to obtain aged wet gel;
(3) and (2) placing the aged wet gel into ethanol and n-hexane, and soaking for 6h at the temperature of 55 ℃, wherein the volume ratio of the ethanol to the n-hexane is 1: 5, drying for 6 hours at the temperature of 80 ℃ under normal pressure to obtain SiO2An aerogel material.
Comparative example 7
Comparative example 7 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 1: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material at least comprises the following steps:
(1) using ethyl orthosilicate as a silicon source, adding ethanol and deionized water into the silicon source, and uniformly stirring, wherein the molar ratio of the silicon source to the ethanol to the deionized water is 1: 4: 2, then adding an acid catalyst, and adjusting the pH value to be 2 to3, stirring for 15min, then adding an alkaline catalyst, adjusting the pH to 7-8, stirring and standing to obtain SiO2Wet gel;
(2) mixing SiO2And (3) placing the wet gel into ethanol, phosphorus-containing oxysilane, alkyl chlorosilane and alkoxy silane, and soaking for 20 hours at the temperature of 55 ℃ to obtain an aged wet gel, wherein the volume ratio of the total volume of the phosphorus-containing oxysilane, the alkyl chlorosilane and the alkoxy silane to the volume of the ethanol is 1: 2;
(3) and (2) placing the aged wet gel into ethanol and n-hexane, and soaking for 6h at the temperature of 55 ℃, wherein the volume ratio of the ethanol to the n-hexane is 1: 5, drying for 6 hours at the temperature of 80 ℃ under normal pressure to obtain SiO2An aerogel material.
Comparative example 8
Comparative example 8 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxysilane, alkylchlorosilane, micromolecular alkane and deionized water.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the phosphorus-containing oxysilane to the alkylchlorosilane is 3: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material at least comprises the following steps:
(1) using ethyl orthosilicate as a silicon source, adding ethanol and deionized water into the silicon source, and uniformly stirring, wherein the molar ratio of the silicon source to the ethanol to the deionized water is 1: 4: 2, adding an acidic catalyst, adjusting the pH value to 2-3, stirring for 15min, then adding an alkaline catalyst, adjusting the pH value to 7-8, stirring, and standing to obtain SiO2Wet gel;
(2) mixing SiO2And (3) placing the wet gel into ethanol, phosphorus-containing oxysilane and alkyl chlorosilane, and soaking for 20 hours at the temperature of 55 ℃ to obtain an aged wet gel, wherein the volume ratio of the total volume of the phosphorus-containing oxysilane and the alkyl chlorosilane to the ethanol is 1: 2;
(3) and (2) placing the aged wet gel into ethanol and n-hexane, and soaking for 6h at the temperature of 55 ℃, wherein the volume ratio of the ethanol to the n-hexane is 1: 5, drying for 6 hours at the temperature of 80 ℃ under normal pressure to obtain SiO2An aerogel material.
Comparative example 9
Comparative example 9 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxy silane to the alkyl chlorosilane is 3: 1: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material at least comprises the following steps:
(1) adding ethanol and deionized water into a silicon source by using tetraethoxysilane and alkoxy silane as the silicon source, and uniformly stirring, wherein the molar ratio of the silicon source to the ethanol to the deionized water is 1: 4: 2, adding an acidic catalyst, adjusting the pH value to 2-3, stirring for 15min, then adding an alkaline catalyst, adjusting the pH value to 7-8, stirring, and standing to obtain SiO2Wet gel;
(2) mixing SiO2And (3) placing the wet gel into ethanol and alkyl chlorosilane, and soaking for 20h at the temperature of 55 ℃ to obtain an aged wet gel, wherein the volume ratio of the alkyl chlorosilane to the ethanol is 1: 2;
(3) and (2) placing the aged wet gel into ethanol and n-hexane, and soaking for 6h at the temperature of 55 ℃, wherein the volume ratio of the ethanol to the n-hexane is 1: 5, drying for 6 hours at the temperature of 80 ℃ under normal pressure to obtain SiO2An aerogel material.
Comparative example 10
Comparative example 10 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane is 3: 1: 0.8.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material at least comprises the following steps:
(1) adding ethanol and deionized water into a silicon source by using tetraethoxysilane and alkoxy silane as the silicon source, and uniformly stirring, wherein the molar ratio of the silicon source to the ethanol to the deionized water is 1: 4: 2, adding an acidic catalyst, adjusting the pH value to 2-3, stirring for 15min, then adding an alkaline catalyst, adjusting the pH value to 7-8, stirring, and standing to obtain SiO2Wet gel;
(2) mixing SiO2And (3) placing the wet gel into ethanol and phosphorus-containing oxysilane, and soaking for 20h at the temperature of 55 ℃ to obtain an aged wet gel, wherein the volume ratio of the phosphorus-containing oxysilane to the ethanol is 1: 2;
(3) and (2) placing the aged wet gel into ethanol and n-hexane, and soaking for 6h at the temperature of 55 ℃, wherein the volume ratio of the ethanol to the n-hexane is 1: 5, drying for 6 hours at the temperature of 80 ℃ under normal pressure to obtain SiO2An aerogel material.
Comparative example 11
Comparative example 11 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is octadecyl trimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkylchlorosilane is triisobutylchlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 1: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material comprises the same steps as example 1.
Comparative example 12
Comparative example 12 of the present invention provides a high temperature resistant silica aerogel material, the preparation raw materials at least include: tetraethoxysilane, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water.
The alkoxy silane is dodecyl (methyl) dimethoxy silane.
The acidic catalyst is phosphoric acid.
The alkaline catalyst is ammonia water.
The procedure for the preparation of the phosphorus-containing oxysilane is as in example 1.
The alkyl chlorosilane is dodecyl dimethyl chlorosilane.
The molar ratio of the ethyl orthosilicate to the alkoxysilane to the phosphoxysilane to the alkylchlorosilane is 3: 1: 0.8: 1.
the small molecular alkane is n-hexane.
The preparation method of the high-temperature-resistant silica aerogel material comprises the same steps as example 1.
Evaluation of Performance
1. And (3) testing the heat conductivity coefficient: the method comprises the steps of adopting a TC3000E thermal conductivity tester of Xian Xixi electronic technology limited to respectively test the thermal conductivity (thermal conductivity K) of a sample, carrying out 3-6 times of measurement on the sample in each measurement period, and taking the average value as a final measurement result.
2. Moisture absorption test: the freshly dried sample was weighed and reported as W1. The sample was placed in air at a humidity of 75% until the weight of the sample did not increase any more (about 48 hours), weighed, and its weight W2 was recorded, the moisture absorption rate was calculated by (W2-W1)/W1X 100%, and the test was repeated 3 to 6 times, and the average value was taken as the final measurement result.
3. And (3) porosity testing: and determining the porosity of the material by using the ratio of the bulk density of the sample to the density of the corresponding compact solid material by adopting a mass-volume direct calculation method, repeatedly testing for 3-6 times, and taking the average value as a final measurement result. 4. And (3) testing the compressive strength: adopting an Electropis electronic dynamic static universal material testing machine of Instron, selecting the linear range of the material according to GB-T1449-2005, and the calculation formula is as follows
Sigma in the formulaSRepresenting the actual compressive strength (MPa); fs represents the strain-corresponding load (N); s represents the actual compression range (mm) of the sample2)。
5. And (3) testing the elastic change rate: and under the same pressure, calculating the elastic change rate of the silicon dioxide aerogel according to the compression degree and the original length, repeatedly testing for 3-6 times, and taking the average value as the final measurement result. The calculation formula is as follows
In the formula, epsilon is the elastic change rate; dL is the amount of compression of the aerogel; l is the initial length of the sample.
6. And (3) testing the combustion heat value: the heat emitted when a sample of unit mass is completely combusted is measured by a calorimeter by adopting a building material combustion heat value test device (PHIMX), the heat is repeatedly tested for 3-6 times, and the average value is taken as the final measurement result.
Table 1 performance characterization test
As can be seen from Table 1, the high temperature resistant silica aerogel material of the present invention can maintain a porous structure, and has high gel skeleton strength, suitable flexibility, and low moisture absorption.
The foregoing examples are merely illustrative and serve to explain some of the features of the method of the present invention. The appended claims are intended to claim as broad a scope as is contemplated, and the examples presented herein are merely illustrative of selected implementations in accordance with all possible combinations of examples. Accordingly, it is applicants' intention that the appended claims are not to be limited by the choice of examples illustrating features of the invention. Also, where numerical ranges are used in the claims, subranges therein are included, and variations in these ranges are also to be construed as possible being covered by the appended claims.
Claims (8)
1. The high-temperature-resistant silica aerogel material is characterized by at least comprising the following preparation raw materials: ethyl orthosilicate, alkoxy silane, an acidic catalyst, a basic catalyst, ethanol, phosphorus-containing oxy silane, alkyl chlorosilane, micromolecular alkane and deionized water;
the preparation method of the high-temperature-resistant silica aerogel material at least comprises the following steps:
(1) preparing silicon dioxide wet gel by using tetraethoxysilane and alkoxy silane as silicon sources;
(2) soaking the silica wet gel in ethanol, phosphorus-containing oxysilane and alkylchlorosilane to obtain an aged wet gel;
(3) soaking the aged wet gel in ethanol and small molecule alkane, and drying to obtain SiO2An aerogel material;
the structural formula of the alkoxy silane is as follows:
wherein R is1、R2Each independently is an alkoxy or alkyl group having 1-2 carbon atoms, R3Is C1-2 alkoxy, R4Is a long chain alkyl group with 8-15 carbon atoms.
2. The refractory silica aerogel material of claim 1, wherein the alkoxysilane is selected from the group consisting of dodecyl (methyl) dimethoxysilane, dodecyl triethoxysilane, tetradecyltriethoxysilane, and dodecyl trimethoxysilane, in combination with one or more other silanes.
3. The high temperature resistant silica aerogel material of claim 1, wherein the phosphoxysilane is prepared from vinyldimethylethoxysilane.
4. The high temperature-resistant silica aerogel material of claim 3, wherein the phosphoxysilane is prepared by reacting vinyldimethylethoxysilane with 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.
5. The refractory silica aerogel material of claim 1, wherein the alkylchlorosilane has the formula:
wherein R ', R ' and R ' are alkyl with 1-4 carbon atoms respectively.
6. The refractory silica aerogel material of claim 5, wherein the alkylchlorosilane is selected from the group consisting of triisobutylchlorosilane, n-butyldimethylchlorosilane, triisopropylchlorosilane, propyldimethylchlorosilane, and tert-butyldimethylchlorosilane in combination.
7. The high temperature resistant silica aerogel material of claim 1, wherein the molar ratio of tetraethoxysilane, alkoxysilane, phosphosilane, alkylchlorosilane is 3: (0.5-2): (0.6-1): 1.
8. the refractory silica aerogel material of claim 1, wherein the acidic catalyst is selected from the group consisting of phosphoric acid, hydrochloric acid, oxalic acid, and sulfuric acid.
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