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Normal-pressure preparation method of high specific surface area intensive-hydrophobicity graphene oxide/silica composite aerogel

A high specific surface area, composite aerogel technology, applied in the direction of chemical instruments and methods, carbon compounds, silicon compounds, etc., can solve the problems of restricting the application of freeze-drying method, affecting the polycondensation process of precursors, and high airgel density. Achieve the effects of improving uneven pore size, shortening gel time, and high specific surface area

Inactive Publication Date: 2019-11-08
SOUTH CHINA UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Although silica airgel has many excellent properties, it has the disadvantages of poor mechanical properties and easy moisture absorption.
The freeze-drying equipment used for drying is expensive, requires a vacuum environment and a very low drying temperature (generally lower than minus 40°C), consumes more energy, and freeze-drying has particularly high requirements for sample solvents. Only water can be used for freeze-drying, so In this patent, when preparing the silica dispersion, ethanol is not added as a cosolvent, which will affect the polycondensation process of the precursor when the gel is formed, making the gel difficult to form, and the prepared airgel has a higher density
further limits the application of freeze-drying

Method used

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  • Normal-pressure preparation method of high specific surface area intensive-hydrophobicity graphene oxide/silica composite aerogel

Examples

Experimental program
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Effect test

Embodiment 1

[0053] Mix ethyl orthosilicate, ethanol, and water at a molar ratio of 1:7:2, stir at room temperature for 20 minutes, add dilute hydrochloric acid to the mixture until pH = 2, and react at room temperature for 8 hours. Add DMF dropwise to the mixture, wherein the mass ratio of DMF to ethyl orthosilicate is 0.15:1, after stirring for 30 minutes, add the ethanol solution of aminopropyltriethoxysilane dropwise to pH = 6, and add to the mixture 0.018g of graphene oxide hydrosol with a mass fraction of 5% was added dropwise, ultrasonicated at 50W for 30min at a temperature of 20°C, and the ethanol solution of aminopropyltriethoxysilane was continued to be added dropwise to the mixed solution to pH =7.2, placed in an ultrasonic cleaner for 8 minutes to form a gel.

[0054] The formed alcohol gel was aged at room temperature for 12 hours, then aged for 24 hours with 20% water / ethanol mixed solution and 20% tetraethyl orthosilicate / ethanol mixed solution with a volume fraction of 100...

Embodiment 2

[0057] Mix ethyl orthosilicate, ethanol, and water at a molar ratio of 1:14:2, stir at room temperature for 25 minutes, add dilute hydrochloric acid to the mixture until pH=2.5, and react at room temperature for 16 hours. Add DMF dropwise to the mixed solution and stir for 30 minutes, wherein the mass ratio of DMF to ethyl orthosilicate is 0.2:1, add the ethanol solution of aminopropyltriethoxysilane dropwise to pH = 6, and add to the mixed solution Add dropwise 0.18g of graphene oxide hydrosol with a mass fraction of 15%, ultrasonicate for 30min at 25°C at a power of 60W, and continue to add the ethanol solution of aminopropyltriethoxysilane dropwise to the mixed solution until pH = 7.5, after 12 minutes in an ultrasonic cleaner, a gel is formed.

[0058] The formed alcohol gel was aged at room temperature for 18 hours, and then aged with 15% water / ethanol mixed solution and 15% tetraethyl orthosilicate / ethanol mixed solution for 36 hours respectively, and respectively with a...

Embodiment 3

[0063] Mix ethyl orthosilicate, ethanol, and water at a molar ratio of 1:14:3, stir at room temperature for 30 minutes, add dilute hydrochloric acid to the mixture until pH=3, and react at room temperature for 24 hours. Add DMF dropwise to the mixture and stir for 30 minutes, wherein the mass ratio of DMF to ethyl orthosilicate is 0.25:1, add the ethanol solution of aminopropyltriethoxysilane drop by drop to pH = 6, and add to the mixture Add dropwise 0.27g of graphene oxide hydrosol with a mass fraction of 20%, ultrasonicate for 30min at 30°C at a power of 80W, and continue to dropwise add an ethanol solution of aminopropyltriethoxysilane to the mixture until pH=8 , placed in an ultrasonic cleaner for 18 minutes to form a gel.

[0064] The formed alcohol gel was aged at room temperature for 24 hours, and then aged for 18 hours with a water / ethanol mixture with a volume fraction of 25% and a tetraethyl silicate / ethanol mixture with a volume fraction of 30%, respectively. 100%...

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Abstract

The invention discloses a normal-pressure preparation method of a high specific surface area intensive-hydrophobicity graphene oxide / silica composite aerogel. The method comprises the following steps:by taking tetraethoxysilane as a precursor, adding a graphene oxide turbid liquid under an acidic condition, adding an ethanol liquid of aminopropyl triethoxy silane and graphene oxide hydrosol, continuously dropping the ethanol liquid of aminopropyl triethoxy silane, forming a graphene oxide / silica composite alcogel under an ultrasonic condition, and performing aging, maturing, solvent replacement, surface modification, and normal-pressure drying, so as to obtain the composite aerogel. By adopting the method, a silane coupling agent, namely the aminopropyl triethoxy silane, is adopted to replace a conventional alkali catalyst, and the aminopropyl triethoxy silane is used as a silicon source and is easy in chemical bond combination with an acidic group carboxyl in the graphene oxide because of an alkali group amino in the aminopropyl triethoxy silane, so that the combination force can be improved, in addition, the formation time of the gel is greatly shortened, and the graphene oxide / silica composite aerogel which is high in specific surface area, intensive in hydrophobicity and low in heat conduction coefficient can be prepared.

Description

technical field [0001] The invention relates to a silica composite aerogel, in particular to a method for preparing a graphene oxide / silicon dioxide composite aerogel at normal pressure with a high specific surface area and strong hydrophobicity, and belongs to the field of nanomaterial preparation. Background technique [0002] Silica airgel is a lightweight nanoporous material with high specific surface area, high porosity, low density, and low thermal conductivity. Silica airgel can be widely used in many fields. For example, in the field of building materials, silica aerogels can be used as thermal insulation materials; in the field of catalysts, silica aerogels can be used as carrier materials; they can also be used in the fields of adsorption and aerospace. [0003] Graphene is currently known as the thinnest material that can be artificially prepared, with a single atomic layer of only 0.33nm in thickness. between adjacent carbon atoms with sp 2 The hybrid arrangeme...

Claims

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Application Information

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IPC IPC(8): C01B33/158C01B33/159C01B33/155C01B32/198
CPCC01B32/198C01B33/155C01B33/1585C01B33/159C01P2004/80C01P2006/10C01P2006/12C01P2006/32
Inventor 袁文辉张孟蝶李莉肖强强
Owner SOUTH CHINA UNIV OF TECH
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