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

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...

AI Technical Summary

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

The Chinese patents whose publication numbers are CN1803602A, CN101318659A, CN101671030A, and CN101973752A use fiber as a reinforcing phase through solvent replacement, surface hydrophobic treatment and fiber reinforcement process to obtain airgel composite materials under normal pressure drying, although these methods all use normal pressure drying , but there are still some deficiencies, which are manifested in that the prepared silica airgel is mainly powder, and it is difficult to obtain bulk materials; additional surface modification steps and solvent exchange steps are used, which prolong the production cycle and increase the cost

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