Bulk-shaped hydrophobic flexible silicon dioxide aerogel and preparation method thereof

A technology of hydrophobic silica and silica, applied in the direction of silica, silica, etc., can solve the problems of difficulty in obtaining bulk material, difficulty in forming bulk, shrinkage and cracking of skeleton, etc., and achieves short cycle and high porosity. , the effect of low cost

Inactive Publication Date: 2016-08-24
李永前
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The preparation of silica airgel adopts the sol-gel method. During the drying process of the wet gel, due to the existence of the gas-liquid interface, a large capillary force is generated and the gel skeleton is anisotropic due to the incompletely uniform pore size of the gel. Anisotropy finally shows that the skeleton is subjected to a large macroscopic stress, which causes the skeleton to shrink and crack, and the network structure collapses, resulting in the prepared airgel is often powder or granules, and it is difficult to form a complete block
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  • Bulk-shaped hydrophobic flexible silicon dioxide aerogel and preparation method thereof
  • Bulk-shaped hydrophobic flexible silicon dioxide aerogel and preparation method thereof
  • Bulk-shaped hydrophobic flexible silicon dioxide aerogel and preparation method thereof

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[0026] One aspect of the present invention provides a method for preparing a bulk hydrophobic silica aerogel. In the preparation method, firstly, the trialkoxysilane containing vinyl functional group is reacted with thiol, and then alcohol is used as a solvent, and two-step acid-base catalysis is adopted to prepare wet gel through sol-gel, and then dry under normal pressure to obtain lumps Silica aerogel. Specifically, as an example, the preparation method of the present invention may include the following steps.

[0027](1) After mixing the vinyl group-containing trialkoxysilane and the thiol in a stoichiometric ratio, the C-S bond-containing trialkoxysilane is prepared by heating or adding an initiator or ultraviolet irradiation. The stoichiometric ratio here refers to the stoichiometric ratio of the addition reaction of thiol and vinyl group. If the heating method is adopted, the heating temperature may be 40-80° C., and the heating time may be 1-5 hours. If an initiator...

Example Embodiment

[0040] Example 1

[0041] Weigh vinyltrimethoxysilane and 1,2-ethanedithiol in a stoichiometric ratio (molar ratio of 2:1) and mix them, and stir and react at 60°C for 4 h to obtain trimethoxysilane containing C-S bonds; 16.0 g of Trimethoxysilane containing C-S bond, 80.0g of ethanol was mixed with 5ml, 0.1mol·L -1 The hydrochloric acid was stirred for 2h; then 5ml was added, 1mol·L -1 The urea aqueous solution was stirred for 5min and left to stand to obtain a gel;

[0042] The gel obtained above was soaked in ethanol at 60°C for 48h, and then dried at 80°C under normal pressure for 2h to obtain a flexible silica aerogel. The above flexible silica aerogel has a density of 0.16 g cm -3 , the porosity is 91.1%, and the BET specific surface area is 200m 2 ·g -1 , the contact angle between distilled water and the surface is 138°, the pore size distribution is 10-500nm, the compressive modulus is 0.37MPa, the flexural modulus is 0.05MPa, and the thermal conductivity is 0.036...

Example Embodiment

[0043] Example 2

[0044] Weigh vinyltrimethoxysilane in a stoichiometric ratio (molar ratio of 2:1) and mix with 1,8-octanedithiol, and irradiate with ultraviolet light for 2 h to obtain trimethoxysilane containing C-S bonds; 2.1 g containing C-S bonds are mixed. of trimethoxysilane, 10.0g of ethanol was mixed with 0.7ml, 0.05mol·L -1 The hydrochloric acid was stirred for 2h; then 0.7ml, 1mol·L was added. -1 The ammonia water was stirred for 5min, and the gel was obtained by standing;

[0045] The gel obtained above was soaked in ethanol at 40°C for 24h, and then dried at 50°C under normal pressure for 48h to obtain a flexible silica aerogel. The above flexible silica aerogel has a density of 0.18 g cm -3 , the porosity is 90.0%, and the BET specific surface area is 240m 2 ·g -1 , the contact angle formed by distilled water and the surface is 148°, the pore size distribution is 10-200nm, the compressive modulus is 0.55MPa, the flexural modulus is 0.15MPa, and the thermal...

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Abstract

The invention relates to a bulk-shaped hydrophobic flexible silicon dioxide aerogel and a preparation method thereof. The preparation method includes the steps of: 1) mixing trialkoxyl silane containing a vinyl group and mercaptan according to the stoichiometric ratio of an addition reaction, and heating the mixture, adding an initiator, or ultraviolet-irradiating the mixture to prepare trialkoxyl silane containing a C-S bond; 2) mixing the trialkoxyl silane containing the C-S bond with an alcohol solvent according to certain ratio, adding an acidic catalyst with stirring for 1-4 h, adding an alkaline catalyst, uniformly stirring the mixture, and allowing the mixture to stand for 0.1-20 h at 15-90 DEG C for gelatinizing the mixture to prepare silicon dioxide wet gel; and 3) naturally-drying or heat-drying the silicon dioxide wet gel under normal pressure to prepare the bulk-shaped hydrophobic flexible silicon dioxide aerogel. The silicon dioxide aerogel has good bulking performance, is high in porosity, has excellent hydrophobicity and flexibility, is low in heat conductivity, and can be applied in the fields of energy saving for buildings, petroleum chemical engineering, sewage treatment and the like.

Description

technical field [0001] The invention relates to the field of chemical material preparation, in particular to a hydrophobic bulk flexible silica airgel material and a preparation method thereof. Background technique [0002] Silica airgel is a new material with a three-dimensional porous structure formed by stacking silica nanoparticles. Because of its low density (0.003~0.8g·cm -3 ), high porosity (80-99.8%), high specific surface area (200-1000m 2 g -1 ), low thermal conductivity (~0.02W·m -1 K -1 ) and other properties make it have very broad prospects in aerospace, chemical industry, energy-saving buildings, military, communications, electronics, metallurgy and other application fields. [0003] Although the research on aerogels has long been a hot spot for researchers, so far there are not many companies that have actually achieved commercial scale production and widely promoted applications. The main reason is the forming problem of silica airgel. The preparation...

Claims

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Application Information

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IPC IPC(8): C01B33/16
Inventor 李永前
Owner 李永前
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