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A kind of atmospheric pressure drying method of silsesquioxane airgel

A technology of silsesquioxane and airgel, which is applied in the direction of airgel preparation, dry solid materials, chemical instruments and methods, etc., can solve the problems of time-consuming, incomplete surface modification and incomplete internal modification of a large number of organic solvents. Uniformity and other issues, to achieve the effect of reducing hydrophobic modification steps, improving solvent replacement efficiency, and reducing capillary force

Active Publication Date: 2021-03-09
AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For the modification of the impregnated surface modifier, due to the large molecular size of the modifier, it will take a long time to diffuse into the gel for modification, especially for thicker gels, it is easy to make the internal modification Inhomogeneous; the modification method combined with the two methods has the best effect, but it also has the problem of using a large amount of solvent
However, the in-situ modification method will cause large drying shrinkage and collapse of the pore structure during the drying process due to incomplete surface modification.
[0004] In order to achieve normal pressure drying, in the prior art, modifiers are often used to modify the surface of the gel skeleton and then perform solvent replacement. For example, hexane with a lower surface tension is used for multiple solvent replacements before drying, but the replacement process requires a lot of organic solvents and takes a long time

Method used

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  • A kind of atmospheric pressure drying method of silsesquioxane airgel
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  • A kind of atmospheric pressure drying method of silsesquioxane airgel

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preparation example Construction

[0033] The invention provides a method for preparing a silsesquioxane airgel by normal pressure drying, comprising the following steps:

[0034] 1) Precursor methyltrimethoxysilane, solvent water, surfactant, catalyst, prepare silica wet gel by sol-gel reaction.

[0035] The mass parts of each chemical component are:

[0036]

[0037] In the present invention, the precursor methyltrimethoxysilane is 15 to 25 parts, preferably 20 to 25 parts; the solvent water is 25 to 35 parts, preferably 25 to 30 parts; the surfactant is 0.2 to 0.4 parts, preferably 0.2 to 0.3 parts; 1 to 3 parts of urea, preferably 1.5 to 2.5 parts, and 0.02 to 0.07 parts of acetic acid, preferably 0.04 to 0.05 parts.

[0038] The precursor methyltrimethoxysilane, solvent water, surfactant, acetic acid and urea are mixed and stirred evenly, and the wet gel is prepared through sol-gel reaction.

[0039] The surfactant of the present invention includes cetyl trimethyl ammonium chloride or cetyl trimethyl ...

Embodiment 1

[0049] Weigh 30 parts by mass of water, add 0.04 parts by mass of acetic acid, then add 0.2 parts by mass of surfactant cetyltrimethylammonium chloride, add 1.5 parts by mass of urea, then add 20 parts by mass of precursor methyl Trimethoxysilane, mixed and stirred evenly for 1 hour for hydrolysis reaction, the temperature is 25°C.

[0050] The polymerization was catalyzed at 70°C to prepare a wet gel.

[0051] The wet gel was subjected to high temperature aging at 80°C for 24 hours.

[0052] The aged wet gel was solvent-substituted with ethanol at a temperature of 25°C for 3 replacements, each replacement time was 12 hours, and the mass ratio of gel to replacement ethanol was 1:3.

[0053] The gel after the solvent replacement was slowly dried at 90° C. to obtain a silsesquioxane airgel.

[0054] figure 1Scanning electron micrographs of the airgel prepared in this example. It can be seen that the microstructure of airgel is a three-dimensional network stacking structure c...

Embodiment 2

[0059] Weigh 30 parts by mass of water, add 0.04 parts by mass of acetic acid, then add 0.3 parts by mass of surfactant cetyltrimethylammonium chloride, add 1.5 parts by mass of urea, then add 25 parts by mass of precursor methyl Trimethoxysilane, mixed and stirred evenly for 1 hour for hydrolysis reaction, the temperature is 25°C.

[0060] The polymerization was catalyzed at 70°C to prepare a wet gel.

[0061] The wet gel was subjected to high temperature aging at 80°C for 24 hours.

[0062] The aged wet gel was solvent-substituted with ethanol at a temperature of 25°C for 3 replacements, each replacement time was 12 hours, and the mass ratio of gel to replacement ethanol was 1:3.

[0063] The gel after the solvent replacement was slowly dried at 90° C. to obtain a silsesquioxane airgel.

[0064] Figure 4 Scanning electron micrographs of the airgel prepared in this example. It can be seen that the microstructure of airgel is a three-dimensional network stacking structure...

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Abstract

The invention discloses a normal pressure drying method of silsesquioxane airgel. In the present invention, methyltrimethoxysilane is used as a precursor, water is used as a solvent and a surfactant is combined, and a silica wet gel with a large pore size can be prepared through a sol-gel process, and then solvent replacement is carried out by ethanol. Silsesquioxane airgel materials can be prepared by directly drying slowly at high temperature. The present invention realizes the in-situ modification of the surface of the gel skeleton by selecting methyltrimethoxysilane as the precursor, and controls the pore structure through the content of the surfactant, which can improve the solvent replacement efficiency and reduce the capillary force during drying, greatly reducing the The amount of organic solvent used in the normal pressure drying process is convenient for large-scale production.

Description

technical field [0001] The invention relates to a method for preparing silsesquioxane airgel, in particular to a method for drying silsesquioxane aerogel under normal pressure, and belongs to the technical field of nanoporous materials. Background technique [0002] As a typical nanoporous material, airgel has received extensive attention in the fields of aerospace thermal protection and civil building energy-saving insulation due to its unique properties such as low density, high specific surface area, and low thermal conductivity. However, in order to keep the pore structure from collapsing during the preparation of airgel materials, supercritical drying methods or normal pressure drying methods are often used. Among them, supercritical drying eliminates the surface tension of the pore liquid, which can keep the pore structure from being deformed by capillary force during the drying process. However, the supercritical drying process is highly dependent on equipment and hi...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): F26B3/00F26B5/00B01J13/00
CPCB01J13/0091F26B3/00F26B5/005
Inventor 雷朝帅张恩爽李文静杨洁颖黄红岩赵英民张昊
Owner AEROSPACE INST OF ADVANCED MATERIALS & PROCESSING TECH
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