Method for preparing hydrophobic aerogel and hydrophobic aerogel prepared therefrom

Abstract

There is provided a method for preparing a surface-modified aerogel with hydrophobicity and a surface-modified aerogel prepared therefrom. The method includes: A) adding a water glass (sodium silicate) to 0.5-2N HCl at a room temperature until the pH of solution is adjusted to 3 to 4; B) forming a silica gel by adding 1.5-10 % (percent) by weight of a non-ionic surfactant to the resulting solution, based on the total weight of the finally prepared silica powder particles, and by adding water glass so that the solution is under an acidic condition of pH 4-6; C) washing the formed silica gel with distilled water and filtering the washed silica gel; D) adding a mixture solvent of 1-40 % (percent) by weight of n-pentanol and 99-60 % (percent) by weight of n-butanol to the silica gel and further adding a silylizing agent; E) putting the mixture solution of the silica gel, the mixture solvent and the silylizing agent into a reactor, separating the solvent and moisture while maintaining a pressure level of 200 to 30 mmHg (millimeter Hg) at a temperature of 45 to 6O DEG C (centigrade) in a reactor, and then removing the moisture and refluxing the solvent again, followed by repeating this process until the moisture is completely removed from the silica gel; and F) closing a reflux line when the moisture is removed from the silica gel, and drying the solvent from the silica gel until thesilica gel is prepared in the powder form. The method may be useful to prepare a silica aerogel in the form of permanently hydrophobic powder in a short time, wherein the a silica aerogel has a highspecific surface area and high functionality, and is prepared by subjecting a wet gel to a solvent exchange process and a silylizing process in a mixture solvent including a silylizing agent at the same time, the wet gel being prepared using a water glass as a raw material and adding a surfactant at a room temperature.

Description

Technical field [0001] The present invention relates to a method for preparing a permanently hydrophobic aerogel in an economical manner in a short time and a permanently hydrophobic aerogel prepared therefrom, and more specifically, to a method for preparing a permanently hydrophobic silica aerogel , Wherein the silica aerogel can be used at low temperature, in a short time, in an economical manner, by simultaneously silylating the aerogel and using a surfactant in a mixed solvent of n-butanol and n-pentanol It is prepared by solvent exchange, and it is possible to recover up to 96% (percent) of the solvent and silylating agent used. Background technique [0002] Recently, as industrial technology has become more and more cutting-edge, interest in aerogels has also increased. Aerogel has a porosity of more than 90% (percent), and the specific surface area is several hundred up to about 1500m 2 / g (m2 / g), but the specific surface area may vary depending on the raw material. Aer...

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Problems solved by technology

In addition, the airgel has a relatively low specific surface area, that is, the specific surface area is 600-700 m 2 / g (square meters per gram), which is considered a disadvantage of the method of using water glass instead of TEOS as raw material

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