Aerogel preparation method

An aerogel and gel technology, applied in the field of aerogel, can solve the problems of labor-consuming solvent replacement, high sublimation pressure, complicated equipment, etc., and achieve the effects of suitable promotion, large porosity and low density

Inactive Publication Date: 2013-06-19
INST OF CHEM CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The disadvantage of this drying method is that the solvent in the gel must be replaced by a solvent with a low expansion coefficient, and the solvent needs to have a higher sublimation pressure.
[0007] In summary, the existing drying methods mainly have the disadvantages of complex equipment, involving high temperature and high pressure, solvent replacement, labor-intensive, waste, and pollution.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] Embodiment 1, use vacuum drying method to prepare silica airgel

[0036] Dissolve 5.0g of tetraethyl orthosilicate in 30mL of ethanol, add 3mL of concentrated hydrochloric acid (mass fraction: 37%), mix well, then add dropwise 2mL of concentrated ammonia water (mass fraction: 28%), stir evenly and let it stand to obtain two silica gel. Replace the solvent of the gel with ethanol 10 times within 3 days to remove unreacted small molecules and impurities. At room temperature, immerse the silica gel in ethanol (it is advisable that the liquid level is just below the gel), and put it in In the vacuum tank, vacuumize the system to make the system pressure reach 10Pa. After the solvent is completely evaporated, the silica airgel can be obtained. its photo as figure 2 As shown, the density is 0.11g / cm 3 , with a porosity of 94%, tested by nitrogen adsorption (such as image 3 Shown) The obtained BET specific surface area is 469m 2 / g.

Embodiment 2

[0037] Example 2, Preparation of Bridged Silsesquioxane Airgel Using Vacuum Drying Method

[0038] Get 3.1g of silsesquioxane monomers with thioether as the bridging segment, the structure is as follows figure 1 Equation 31 in

[0039]

[0040] Dissolve it in 30mL of ethanol, add 6mL of concentrated hydrochloric acid, mix well, put it in an oven at 60°C to make it gel. Replace the solvent of the gel with ethanol 10 times within 3 days to remove unreacted small molecules and impurities. At room temperature, immerse the gel in ethanol (it is better if the liquid level is just below the gel), and put it in a vacuum tank In the process, vacuumize the system pressure to 20Pa, and after the solvent is completely volatilized, bridged silsesquioxane airgel can be obtained. its photo as Figure 4 As shown, the density is 0.065g / cm 3 , with a porosity of 97%, tested by nitrogen adsorption (such as Figure 5 Shown) The obtained BET specific surface area is 584m 2 / g.

Embodiment 3

[0041] Embodiment 3, use vacuum drying method to prepare RF airgel

[0042] Take 1.9g of resorcinol (Resorcinol) and 1.0g of formaldehyde (Formaldehyde), dissolve it in 30mL of water, add 12mg of sodium carbonate, and gel at 85°C. Change the water in the gel 10 times within 3 days to remove unreacted small molecules and impurities. At room temperature, immerse the gel in water (it is advisable that the liquid level is just below the gel), put it in a vacuum tank, and pump it. Make the system pressure up to 1Pa under vacuum, and after the solvent is completely volatilized, RF airgel can be obtained. its photo as Figure 6 As shown, the density is 0.10g / cm 3 , with a porosity of 94%, tested by nitrogen adsorption (such as Figure 7 Shown) The obtained BET specific surface area is 536m2 / g.

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Abstract

The invention discloses an aerogel preparation method. The aerogel preparation method comprises the following steps of immersing gel into a solvent, putting the gel solution into a vacuum tank, and carrying out vacuum-pumping so that the solvent is evaporated in vacuum and after the solvent is completely evaporated, aerogel is obtained. The aerogel preparation method is a fast drying method. In vacuum-pumping, the solvent in the gel is fast volatilized so that a large amount of heat is taken away and a system temperature is reduced; reactivity of active groups in a gelskeleton is reduced; and irreversible collapse possibility is reduced. The gelskeleton has strong rigidity at a low temperature so that a gel structure is kept well. The aerogel obtained by the aerogel preparation method has low density, large porosity and a high specific surface area, and has standard features of aerogel prepared by a supercritical method.

Description

technical field [0001] The invention relates to a preparation method of airgel, which belongs to the technical field of airgel. Background technique [0002] Airgel is a porous solid material that replaces the solvent in the gel with air through a certain method while maintaining the integrity of the porous structure of the gel. Airgel has a variety of unique properties, such as extremely low density, high porosity, high specific surface area, low thermal conductivity, etc., in many fields such as sensors, optical devices, heat insulation materials, catalysts, and acoustic damping materials. Broad application prospects. [0003] There are three main drying methods currently used to prepare aerogels: [0004] 1) Supercritical drying: Supercritical fluid has no gas-liquid interface and no surface tension, which can avoid the generation of capillary force during the volatilization process, so as to keep the skeleton structure of the gel from being damaged. Transforming the s...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B01J13/00
Inventor 王真戴珍赵宁张小莉徐坚
Owner INST OF CHEM CHINESE ACAD OF SCI
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