CN112125311A - A kind of hydrophobic aerogel powder and rapid preparation method thereof - Google Patents

Abstract

The invention provides hydrophobic aerogel powder and a rapid preparation method thereof, belonging to the technical field of nano porous materials. According to the invention, the aerogel is rapidly prepared by enhancing the gel framework strength, modifying the surface of the nano particles in situ and the like, and then is directly dried under normal pressure by pulverization to rapidly obtain aerogel powder, so that the preparation period is short, and the application of the aerogel in the fields of heat insulation, heat preservation, adsorption separation and the like is facilitated.

Description

A kind of hydrophobic aerogel powder and rapid preparation method thereof

technical field

The invention relates to a hydrophobic aerogel powder and a rapid preparation method thereof, belonging to the technical field of nano-porous materials.

Background technique

As a typical nanoporous material, aerogel has been widely used in the fields of thermal insulation, gas adsorption and oil-water separation due to its unique nano-network structure, low and high specific surface area, low thermal conductivity, high adsorption and other properties. focus on. However, because the drying methods of aerogels are mostly supercritical drying or atmospheric drying with complicated and lengthy processes, the preparation efficiency of aerogels is low, which seriously limits its practical application.

Using methyltrimethoxysilane as a single precursor, Professor Kanamori of Kyoto University, Japan, prepared an organic-inorganic hybrid silica aerogel through a surfactant-water system. However, the drying needs to replace the solvent with ethanol and then perform supercritical drying, the preparation period is long, and the equipment dependence is large. However, the aerogel prepared with methyltrimethoxysilane as the precursor and alcohol as the solvent, due to the microscopic phase separation, the pore structure size is large, the nanopore structure is limited, and the specific surface area is low, which still needs to be dried before atmospheric pressure. A solvent replacement step is performed, which affects the preparation cycle. Therefore, a rapid preparation method of aerogel powder is urgently needed to meet the application requirements in practical engineering.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a hydrophobic aerogel powder and a rapid preparation method thereof, so as to overcome the defects in the prior art.

The invention provides a rapid preparation method of hydrophobic aerogel powder, comprising the following steps:

Weigh 80-110 parts by mass of the precursor methyltrimethoxysilane, 100-140 parts of water, and 1.5-2.5 parts of surfactant, mix them evenly, and carry out the process under the condition of 0-0.2 parts of acidic catalyst. hydrolysis;

Mixing the hydrolyzed sol system with 0.001-0.004 parts of basic catalyst ammonium fluoride, and catalyzing polymerization to form wet gel;

The obtained wet gel is pulverized to obtain wet gel powder;

Wash the wet gel powder in clean water to wash out residual organic reagents and adsorbed surfactants;

The wet gel powder after water washing is directly dried under normal pressure to obtain the final hydrophobic aerogel powder.

Further, methyltrimethoxysilane is preferably 90-100 parts; water is preferably 110-130 parts; surfactant is preferably 1.8-2.2 parts; acid catalyst is preferably 0.05-0.15 parts; ammonium fluoride is preferably 0.002 ~ 0.003 parts.

Further, the surfactant includes an ionic surfactant or a block copolymer surfactant, and the ionic surfactant includes cetyltrimethylammonium chloride or cetyltrimethyl ammonium chloride Ammonium bromide, the block copolymer type surfactant includes polyoxyethylene-polyoxypropylene ether block copolymer.

Further, the acidic catalyst includes an inorganic acid or an organic acid, the inorganic acid includes hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid, and the organic acid includes acetic acid, oxalic acid or citric acid.

Further, the hydrolysis temperature is 10-60°C, preferably 20-40°C;

Further, the hydrolysis time is 10～30min, preferably 15～25min;

Further, after mixing with ammonium fluoride, the temperature is adjusted to be 20-60°C, preferably 40-50°C.

Further, the pulverization treatment temperature is 10 to 50°C, preferably 20 to 30°C.

Further, the water washing temperature is 20-70°C, preferably 30-50°C;

Further, the washing time is 10-30 min.

Further, the drying temperature under normal pressure is 40-100°C, preferably 60-80°C.

The present invention also provides a hydrophobic aerogel powder, which is prepared by the above method.

Compared with the prior art, the beneficial effects obtained by the method of the present invention are: compared with the aerogel prepared by the traditional method, which does not have a typical nano-network structure, the method of the present invention adopts water as the solvent, the surfactant controls the pore structure, and the catalyst fluorine Ammonium sulfide enhances the gel skeleton, directly drying, avoiding the use of organic solvents, the prepared aerogel powder maintains the nano-scale pore size distribution, and at the same time has a high specific surface area, small pore size, and typical gas Gel nanonetwork structure. The traditional method of preparing aerogel powder requires a lengthy solvent replacement process, and the preparation period is more than 2 days. In contrast, the method of the present invention reduces the shortest period of preparing aerogel powder to 2 hours. , the preparation cycle is greatly reduced.

Description of drawings

FIG. 1 is an appearance diagram of the hydrophobic aerogel powder prepared in Example 1 of the present invention.

2 is a scanning electron microscope image of the hydrophobic aerogel prepared in Example 1 of the present invention.

Detailed ways

In order to make the above objects, features and advantages of the present invention more clearly understood, the present invention will be further described in detail below through specific embodiments and accompanying drawings.

Example 1

Weigh 120 parts by mass of solvent water, add 0.1 parts by mass of acetic acid, then add 2.0 parts by mass of the surfactant cetyltrimethyl ammonium chloride, stir evenly and add 100 parts by mass of the precursor methyltrimethoxy Hydrolysis of the base silane was carried out with stirring.

The hydrolysis temperature was 25°C, and the hydrolysis time was 20 min.

After hydrolysis, 0.003 parts by mass of ammonium fluoride was added for stirring, and the temperature was 20° C., and the polymerization was waited for.

The wet gel obtained by polymerization was pulverized at a temperature of 25°C.

The wet gel powder was washed with water at a temperature of 50° C. and a washing time of 20 minutes.

The wet gel powder after water washing was directly dried under normal pressure at a drying temperature of 40° C. to obtain a hydrophobic aerogel powder.

The apparent picture of the obtained aerogel powder is shown in Figure 1, and the scanning electron microscope picture is shown in Figure 2.

Example 2

Weigh 100 parts by mass of solvent water, add 0 parts by mass of acetic acid, then add 1.5 parts by mass of the surfactant cetyltrimethyl ammonium chloride, stir evenly and add 80 parts by mass of the precursor methyltrimethoxy Hydrolysis of the base silane was carried out with stirring.

The hydrolysis temperature was 10°C, and the hydrolysis time was 10 min.

After the hydrolysis, 0.001 part by mass of ammonium fluoride was added for stirring, and the temperature was 40° C., and it was then polymerized.

The wet gel obtained by polymerization was pulverized at a temperature of 10°C.

The wet gel powder was washed with water at a temperature of 20° C. and a washing time of 30 minutes.

The wet gel powder after water washing was directly dried under normal pressure at a drying temperature of 80° C. to obtain a hydrophobic aerogel powder.

Example 3

Weigh 140 parts by mass of solvent water, add 0.2 parts by mass of acetic acid, then add 2.5 parts by mass of the surfactant cetyltrimethyl ammonium chloride, stir evenly and add 110 parts by mass of the precursor methyltrimethoxy Hydrolysis of the base silane was carried out with stirring.

The hydrolysis temperature was 60°C, and the hydrolysis time was 30 min.

After hydrolysis, 0.004 parts by mass of ammonium fluoride was added for stirring, and the temperature was 60° C., and the polymerization was waited for.

The wet gel obtained by polymerization was pulverized at a temperature of 50°C.

The wet gel powder was washed with water at a temperature of 70° C. and a time of 10 min.

The wet gel powder after water washing was directly dried under normal pressure at a drying temperature of 100° C. to obtain a hydrophobic aerogel powder.

Example 4

Weigh 100 parts by mass of solvent water, add 0.2 parts by mass of acetic acid, then add 2.5 parts by mass of the surfactant cetyltrimethyl ammonium chloride, stir evenly and add 110 parts by mass of the precursor methyltrimethoxy Hydrolysis of the base silane was carried out with stirring.

The hydrolysis temperature was 25°C, and the hydrolysis time was 15 min.

After hydrolysis, 0.001 part by mass of ammonium fluoride was added for stirring, and the temperature was 25° C., and it was then polymerized.

The wet gel obtained by polymerization was pulverized at a temperature of 25°C.

The wet gel powder was washed with water at a temperature of 50° C. and a washing time of 15 minutes.

The wet gel powder after water washing was directly dried under normal pressure at a drying temperature of 80° C. to obtain a hydrophobic aerogel powder.

Example 5

Weigh 140 parts by mass of solvent water, add 0 parts by mass of acetic acid, then add 1.5 parts by mass of the surfactant cetyltrimethyl ammonium chloride, stir evenly and add 80 parts by mass of the precursor methyltrimethoxy Hydrolysis of the base silane was carried out with stirring.

The hydrolysis temperature was 60°C, and the hydrolysis time was 30 min.

After hydrolysis, 0.004 parts by mass of ammonium fluoride was added for stirring, and the temperature was 25° C., and the polymerization was waited for.

The wet gel obtained by polymerization was pulverized at a temperature of 25°C.

The wet gel powder was washed with water, the washing temperature was 50°C, and the washing time was 25 min.

The wet gel powder after water washing was directly dried under normal pressure at a drying temperature of 100° C. to obtain a hydrophobic aerogel powder.

Comparative ratio

The traditional method is used to prepare, and the preparation process is as follows:

120 parts by mass of solvent ethanol was weighed, 0.1 part by mass of acetic acid was added, and after stirring uniformly, 100 parts by mass of the precursor methyltrimethoxysilane was added and stirred for hydrolysis.

The hydrolysis temperature was 25°C, and the hydrolysis time was 20 min.

After hydrolysis, 0.003 parts by mass of ammonium fluoride was added for stirring, and the temperature was 20° C., and the polymerization was waited for.

The wet gel obtained by polymerization was pulverized at a temperature of 25°C.

The wet gel powder was washed with water at a temperature of 50° C. and a washing time of 20 minutes.

The wet gel powder after water washing was directly dried under normal pressure at a drying temperature of 40° C. to obtain a hydrophobic aerogel powder.

The aerogel structural parameters are shown in Table 1.

Table 1 Structure Characterization Results of Aerogel Samples Prepared by Different Examples

Example Pore size distribution (nm) Specific surface area (m²/g) Pore volume (cm³/g) Example 1 40-60 316.1 1.25 Example 2 30-50 296.2 1.34 Example 3 30-60 287.3 1.22 Example 4 30-50 305.5 1.43 Example 5 30-60 298.1 1.37 Comparative ratio >100 30.2 0.89

It can be seen from the above Table 1 that the aerogel powder prepared by the method of the present invention maintains the nano-scale pore size distribution and has a relatively high specific surface area, indicating that the pore size is small and is a typical aerogel structure. The aerogel powder prepared by the method, as in the comparative example, is actually a porous foam material, which does not have the typical nano-network structure of aerogel.

The above-mentioned embodiments are only the preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Several improvements and modifications are made, which should also be considered within the scope of protection of the present invention.

Claims (10)

1. a rapid preparation method of hydrophobic aerogel powder, is characterized in that, comprises the following steps: Weigh 80-110 parts by mass of the precursor methyltrimethoxysilane, 100-140 parts of water, and 1.5-2.5 parts of surfactant, mix them evenly, and carry out the process under the condition of 0-0.2 parts of acidic catalyst. hydrolysis; Mixing the hydrolyzed sol system with 0.001-0.004 parts of basic catalyst ammonium fluoride, and catalyzing polymerization to form wet gel; The obtained wet gel is pulverized to obtain wet gel powder; Wash the wet gel powder in clean water to wash out residual organic reagents and adsorbed surfactants; The wet gel powder after water washing is directly dried under normal pressure to obtain the final hydrophobic aerogel powder. 2. The method according to claim 1, wherein the methyltrimethoxysilane is preferably 90-100 parts; the water is preferably 110-130 parts; the surfactant is preferably 1.8-2.2 parts; the acid catalyst is preferably It is 0.05-0.15 part; Ammonium fluoride is preferably 0.002-0.003 part. 3. The method of claim 1, wherein the surfactant comprises an ionic surfactant or a block copolymer surfactant, and the ionic surfactant comprises cetyltrimethylammonium chloride Or cetyltrimethylammonium bromide, the block copolymer type surfactant includes polyoxyethylene-polyoxypropylene ether block copolymer. 4. The method of claim 1, wherein the acidic catalyst comprises inorganic acid or organic acid, the inorganic acid comprises hydrochloric acid, sulfuric acid, phosphoric acid or nitric acid, and the organic acid comprises acetic acid, oxalic acid or citric acid. 5. The method of claim 1, wherein the hydrolysis temperature is 10-60°C, and the hydrolysis time is 10-30 min. 6. The method according to claim 1, characterized in that, after mixing with ammonium fluoride, the control temperature is 20-60°C. 7. The method of claim 1, wherein the pulverization treatment temperature is 10-50°C. 8. The method of claim 1, wherein the washing temperature is 20-70°C, and the washing time is 10-30 min. 9. The method of claim 1, wherein the drying temperature under normal pressure is 40-100°C. 10 . A hydrophobic aerogel powder, characterized in that, it is prepared by the method of claim 1 .

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