Ambient pressure drying method of silsesquioxane aerogel

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

Active Publication Date: 2020-02-21
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 shri

Method used

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  • Ambient pressure drying method of silsesquioxane aerogel
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  • Ambient pressure drying method of silsesquioxane aerogel

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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-replaced with ethanol at a temperature of 25°C for three 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 ...

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 an ambient pressure drying method of silsesquioxane aerogel. According to the ambient pressure drying method of the silsesquioxane aerogel, methyltrimethoxysilane is taken as aprecursor, water is taken as a solvent to be combined with a surfactant, silica wet gel with a large aperture size can be prepared through a sol-gel process, after solvent replacement by ethanol is carried out, the silica wet gel is directly and slowly dried at high temperature, and a silsesquioxane aerogel material can be prepared. According to the ambient pressure drying method of the silsesquioxane aerogel, the methyltrimethoxysilane is selected as the precursor, so that the in-situ modification of a gel skeleton surface is realized, the aperture structure is controlled by the surfactant content, the solvent replacement efficiency can be improved, the capillary force during drying can be reduced, the use amount of organic solvent in the ambient pressure drying process is greatly reduced, and the large-scale production is facilitated.

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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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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