Method for preparing hydrophobic SiO2 aerogel

An aerogel and hydrophobic technology, which is applied in the field of preparing hydrophobic SiO2 aerogels, can solve problems such as large-scale application constraints, aerogels affecting performance, and unsafety, and achieve easy-to-control reactions, high porosity, and hydrophobic good sex effect

Inactive Publication Date: 2009-08-12
YANGZHOU TIANCHEN FINE CHEM +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, the requirements for supercritical drying equipment are high, there are unsafe factors, and the obtained airgel is easy to absorb water, which greatly affects its performance, and its large-scale application is greatly restricted.

Method used

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  • Method for preparing hydrophobic SiO2 aerogel

Examples

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Effect test

example 1

[0026] Measure 16.1ml of tetraethyl orthosilicate, add it to 16.8ml of absolute ethanol, add dropwise 6.4ml of oxalic acid aqueous solution with a concentration of 0.008M to the above system under stirring, and wait until all the drops are finished, at room temperature After hydrolysis under stirring for 24 hours, 0.5 ml of ammonia water with a concentration of 0.5 M was added dropwise to the hydrolysis system, and gelation occurred after a few minutes to obtain 38 ml of silica wet gel.

[0027] The water in the wet gel was replaced with absolute ethanol 3 times within 32-40 hours, the volume ratio of absolute ethanol to gel was 2:1, and the replacement time was 10-15 hours each time.

[0028] Then use 76ml of n-hexane to replace ethanol three times within 32-40 hours. After the replacement is completed, add hexamethyldisilazane / n-hexane solution with a volume ratio of 1:4, and carry out 20 After ~28 hours of surface modification, the unreacted hexamethyldisilazane was replace...

example 2

[0032] Measure 16.1ml of tetraethyl orthosilicate, add it to 16.8ml of absolute ethanol, add dropwise 6.4ml of oxalic acid aqueous solution with a concentration of 0.006-0.01M to the above system under stirring, and wait until all the drops are finished, After hydrolysis at room temperature for 24 hours, 0.5 ml of ammonia water with a concentration of 0.5 M was added dropwise to the hydrolysis system, and gelation occurred after a few minutes to obtain 38 ml of silica wet gel.

[0033] The water in the wet gel was replaced with absolute ethanol 2-3 times within 36 hours, the volume ratio of absolute ethanol to gel was 2:1, and the replacement time was 10-15 hours each time.

[0034] Then use 76ml of n-hexane to replace ethanol 3 times within 32-40 hours. After the replacement is completed, add a dimethyldichlorosilane / n-hexane solution with a volume ratio of 1:4 to it, and carry out the process at an ambient temperature of 50-60°C. After 24 hours of surface modification, the u...

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Abstract

The invention relates to a method for preparing lyophobic SiO2 aerogel, belonging to the technical field of new material preparation. The method comprises the steps: tetraethyl orthosilicate, absolute ethyl alcohol and oxalic acid solution are firstly mixed in a container for sealing, and then the mixed solution is put into water bath, hydrolyzed under agitation and added with ammonia dropwise; when gel is formed, the absolute ethyl alcohol is added into the gel for exchanging the water in the gel; n-hexane is used for exchanging ethanol in the gel; wet gel which is processed by solvent exchange and aging is dipped into the mixed solution of modifying agent and n-hexane for surface modification, then the n-hexane is added for exchanging the unreacted modifying agent; finally, a test tube is sealed by a aluminum foil provided with a needle hole and is placed into an oven for classified drying under normal pressure, so that the modified SiO2 aerogel is obtained. The SiO2 aerogel prepared by the method has the advantages of high porosity, large specific surface area, good hydrophobic property, etc. The method has the advantages of mild reaction condition, easy control of the reaction as well as simple and convenient process flow.

Description

technical field [0001] The invention belongs to the technical field of preparation of new materials, in particular to the preparation of hydrophobic SiO 2 Airgel method. Background technique [0002] SiO 2 Airgel is a lightweight nanoporous amorphous solid material with many excellent properties, such as high porosity (greater than 99%), low density (less than 0.3g / cm 3 ), large specific surface area (1600m 2 / g), low thermal conductivity (<0.02W / mK), low sound velocity (less than 100m / s), low refractive index (1.01~1.10), etc. Therefore, SiO 2 Aerogels have broad application prospects in the fields of thermal insulation materials, acoustic impedance coupling materials, rocket liquid propellant storage media, Cherenkov detectors, catalysts and catalyst carriers, high-efficiency thermal insulation materials, and the preparation of high-efficiency rechargeable batteries. Adsorbents also have good application prospects in wastewater treatment, air purification and nucle...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C01B33/14
Inventor 谢吉民朱建军陈国云刘润兴
Owner YANGZHOU TIANCHEN FINE CHEM
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