Polyethyleneimine-aerogel flexible film and preparation method thereof

Abstract

The invention discloses a polyethyleneimine-aerogel flexible film and a preparation method thereof, and belongs to the field of aerogel composite materials. The preparation method of the aerogel flexible membrane provided by the invention comprises the following steps: carrying out polymerization cross-linking on amino groups on polyethyleneimine and hydroxyl groups on the surface of aerogel which is not hydrophobically modified, then carrying out hydrophobic modification through a modifier, and finally carrying out supercritical drying to obtain the polyethyleneimine-aerogel flexible membrane. The preparation method of the polyethyleneimine-aerogel flexible film provided by the invention is simple, and the prepared film has thermal insulation performance and flexibility, and can be used in the field of thermal insulation.

Description

Technical Field

[0001] The invention belongs to the field of aerogel composite materials, in particular to a polyethyleneimine-aerogel flexible film and a preparation method thereof. Background Art

[0002] Aerogel is a nanoporous amorphous solid material with a network structure. It has the characteristics of low density, high porosity, low thermal conductivity and low refractive index. It is a new type of lightweight and efficient thermal insulation material. Due to its unique low density, high porosity and large specific surface area, it has been widely used in aerospace, energy-saving buildings, agriculture and forestry, biomedicine and other fields. Although aerogel only accounts for 3% of the market as an emerging material, it has shown great potential in oil and gas pipelines (except LNG pipelines), refining projects, industrial insulation and other fields. In the future, the application of aerogel in construction, thermal, acoustics, medicine and health, aerospace, metallurgy, chemical industry and other fields is expected to be more extensive.

[0003] A major drawback of aerogel is its structural fragility and lack of sufficient flexibility and stretchability, which limits its promotion in other fields, such as the aerogel thermal insulation clothing introduced earlier. Therefore, improving the flexibility of aerogel has become the key to expanding its application range. For example, the patent application with application number 202410104636.4 discloses a flexible hydrophobic silica-polyimide aerogel membrane and a preparation method thereof; a flexible hydrophobic silica-polyimide aerogel membrane, comprising the following raw materials in parts by weight: 0.6-1.4 parts of aromatic dianhydride, 0.4-0.9 parts of aromatic diamine, 0.05-0.3 parts of cross-linking agent, 10-17 parts of organic solvent, 0.05-0.5 parts of hydrophobically modified aerogel powder, 1-4 parts of dehydrating agent, 1-4 parts of catalyst, and the hydrophobically modified aerogel powder is organosilicon-modified silica aerogel powder. The aerogel membrane prepared by this patent has poor thermal insulation performance and no obvious improvement in mechanical properties. Summary of the invention

[0004] In view of the problem that aerogel is fragile, the present invention provides a polyethyleneimine-aerogel flexible film having excellent thermal insulation performance and flexibility and a preparation method thereof.

[0005] The present invention utilizes -OH on the surface of aerogel and polyethyleneimine reaction monomer with amino group to attract each other through positive and negative charges, and then the two form a network structure, and finally prepare polyethyleneimine-aerogel flexible film through supercritical drying.

[0006] The method for preparing the polyethyleneimine-aerogel flexible film comprises the following steps:

[0007] S1. Prepare a polyethyleneimine aqueous solution and a hydrophilic aerogel aqueous solution respectively, mix the two solutions, and allow them to fully react under stirring;

[0008] S2. After the reaction in step S1 is completed, alcohol, hydrochloric acid and a modifier are added to the mixed solution to allow it to react fully under stirring;

[0009] S3, after the polyethyleneimine-aerogel solution in step S2 is washed and the solution becomes neutral, supercritical drying is performed to obtain a polyethyleneimine-aerogel flexible film.

[0010] Preferably, the concentration of the polyethyleneimine aqueous solution is 1wt%-4wt%.

[0011] Preferably, the concentration of the hydrophilic aerogel aqueous solution is 1wt%-8wt%.

[0012] Preferably, the hydrophilic aerogel comprises hydrophilic silica aerogel or hydrophilic alumina aerogel.

[0013] Preferably, the mass ratio of the polyethyleneimine to the hydrophilic aerogel is 1:1-8.

[0014] Preferably, in step S1, the stirring time is 10 to 15 hours.

[0015] Preferably, in step S1, the stirring rate is 100-300 rpm / min.

[0016] Preferably, in step S1, the reaction temperature is 40-70°C.

[0017] Preferably, in step S2, the alcohol includes methanol, ethanol, isopropanol or n-butanol.

[0018] Preferably, in step S2, the concentration of the hydrochloric acid is 4 to 12 mol / L.

[0019] Preferably, in step S2, the modifier includes dimethyldiethoxysilane, hexamethyldisiloxane or hexamethyldisilazane.

[0020] Preferably, in step S2, the amount of alcohol added is 3 wt% to 7 wt% of the mixed solution in step S1. Alcohol is used as a solvent, and too little addition will affect the modification effect of the aerogel.

[0021] Preferably, in step S2, the amount of hydrochloric acid added is 9 wt% to 10 wt% of the mixed solution in step S1. Hydrochloric acid is used as a catalyst for modification, and too little amount of hydrochloric acid will also affect the modification effect.

[0022] Preferably, in step S2, the amount of the modifier added is 5wt% to 10wt% of the mixed solution in step S1.

[0023] Preferably, in step S2, the reaction temperature is 60° C. and the reaction time is 2 to 5 hours. The reaction temperature will affect the modification effect and ultimately its thermal conductivity.

[0024] Preferably, in step S3, the cleaning includes alkaline washing and water washing.

[0025] Preferably, the alkali washing solution is an aqueous solution of sodium hydroxide and potassium hydroxide with a concentration of 0.1% to 1%.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] Aerogels are fragile and cannot be made into flexible films independently, which limits their application areas. The present invention forms a composite material with a network structure by combining it with polyethyleneimine having a chain structure, which gives it flexibility while retaining its excellent thermal insulation properties, thereby expanding its application areas. In addition, the preparation method provided by the present invention has a simple production process and reduces production costs. DETAILED DESCRIPTION

[0028] The technical scheme of the present invention is further described below by way of examples. The raw materials used in the examples can be purchased from the market or prepared by conventional methods.

[0029] Example 1

[0030] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0031] S1. Prepare 1 wt% polyethyleneimine aqueous solution and 1 wt% silica aerogel aqueous solution of the same mass, take 100 g of each and stir and mix for 12 h;

[0032] S2. After the reaction in step S1 is completed, 5 wt% of n-butanol, 100 wt% of dimethyldiethoxysilane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0033] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (pressure 14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0034] Example 2

[0035] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0036] S1. Prepare 1 wt% polyethyleneimine aqueous solution and 4 wt% silica aerogel aqueous solution of the same mass, take 100 g of each and stir and mix for 12 h;

[0037] S2. After the reaction in step S1 is completed, 5 wt% of isopropanol, 100 wt% of hexamethyldisilazane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0038] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (pressure 14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0039] Example 3

[0040] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0041] S1. Prepare 1 wt% polyethyleneimine aqueous solution and 8 wt% silica aerogel aqueous solution of the same mass, take 100 g of each and stir and mix for 12 h;

[0042] S2. After the reaction in step S1 is completed, 5 wt% of ethanol, 100 wt% of dimethyldiethoxysilane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0043] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0044] Example 4

[0045] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0046] S1. Prepare 2wt% polyethyleneimine aqueous solution and 8wt% silica aerogel aqueous solution of the same mass, take 100g of each and stir and mix for 12h;

[0047] S2. After the reaction in step S1 is completed, 5 wt% of n-butanol, 100 wt% of dimethyldiethoxysilane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0048] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0049] Example 5

[0050] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0051] S1. Prepare 3wt% polyethyleneimine aqueous solution and 8wt% silica aerogel aqueous solution of the same mass, take 100g of each and stir and mix for 12h;

[0052] S2. After the reaction in step S1 is completed, 5 wt% of n-butanol, 100 wt% of dimethyldiethoxysilane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0053] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0054] Example 6

[0055] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0056] S1. Prepare 4wt% polyethyleneimine aqueous solution and 8wt% silica aerogel aqueous solution of the same mass, take 100g of each and stir and mix for 12h;

[0057] S2. After the reaction in step S1 is completed, 5 wt% of n-butanol, 100 wt% of hexamethyldisilazane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0058] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue is poured on a special mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0059] Example 7

[0060] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0061] S1. Prepare 4wt% polyethyleneimine aqueous solution and 4wt% silica aerogel aqueous solution of the same mass, take 100g of each and stir and mix for 12h;

[0062] S2. After the reaction in step S1 is completed, 5 wt% of n-hexane, 100 wt% of dimethyldiethoxysilane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0063] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0064] Example 8

[0065] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0066] S1. Prepare 4wt% polyethyleneimine aqueous solution and 6wt% silica aerogel aqueous solution of the same mass, take 100g of each and stir and mix for 12h;

[0067] S2. After the reaction in step S1 is completed, 5 wt% of methanol, 100 wt% of hexamethyldisiloxane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0068] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0069] Example 9

[0070] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0071] S1. Prepare 4wt% polyethyleneimine aqueous solution and 4wt% silica aerogel aqueous solution of the same mass, take 100g of each and stir and mix for 12h;

[0072] S2. After the reaction in step S1 is completed, 5 wt% of isopropanol, 100 wt% of dimethyldiethoxysilane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0073] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0074] Example 10

[0075] A polyethyleneimine-aerogel flexible film is prepared by the following steps:

[0076] S1. Prepare 4wt% polyethyleneimine aqueous solution and 8wt% silica aerogel aqueous solution of the same mass, take 100g of each and stir and mix for 12h;

[0077] S2. After the reaction in step S1 is completed, 5 wt% of n-butanol, 100 wt% of hexamethyldisilazane and 8 wt% of hydrochloric acid are added to the mixed solution in sequence, and the mixture is stirred and reacted at 60° C. for 3 h;

[0078] S3. After the reaction is completed, the modified polyethyleneimine-aerogel solution is washed with alkali and water until the solution is neutral. Finally, the glue solution is poured on a mold made of polytetrafluoroethylene, with a rectangular shape, a size of 200*200mm, and a depth of 10mm. The polyethyleneimine-aerogel flexible membrane is obtained by supercritical drying (14-16Mpa, temperature 60°C, and drying for 12h after stabilizing the pressure and temperature).

[0079] Performance Testing

[0080] Thermal insulation performance test: Take a polyethyleneimine-aerogel flexible film with a total thickness of no less than 5mm and measure it by the transient plane heat source (TPS) method according to the method specified in ISO22007-2. Place the hot disk probe in the test sample to form a sandwich structure, and measure the thermal physical properties of the sample to be tested by the temperature coefficient of resistance through the temperature change of the test probe. Each different group of tests is carried out three times, and the average of the three results is taken. The results are shown in Table 1.

[0081] Mechanical properties test:

[0082] Tensile strength: Cut the sample into a rectangle with a size of (235±5)*(75±2)mm, put it into a universal testing machine, and perform a tensile strength test at a speed of 5cm / min. The number of test samples is not less than 5, and the final result is the average value. The results are shown in Table 1.

[0083] Elastic recovery rate: The sample was tested using Shenzhen Sansi Zongheng Electronic Universal Testing Machine UTM4204. The sample was placed on the fixture, the gauge length of the working part was 100mm, and after stretching 50mm at a strain rate of 50%, it was retracted at the same speed, and the irrecoverable length of the sample was measured and the ER elastic recovery rate value was calculated by the following calculation formula: ER = (100-L) / 100 × 100%, L is the irrecoverable length of the sample after stretching 50mm, in mm, and the results are shown in Table 1.

[0084] Table 1 Performance data of polyethyleneimine-aerogel flexible films in Examples 1 to 10

[0085]

[0086]

[0087] According to Table 1, Example 6 has the worst thermal conductivity and the best thermal insulation performance; Example 10 has the best tensile strength, indicating that increasing the content of polyethyleneimine is conducive to improving the tensile properties; Example 8 has the best elastic recovery ability, indicating that a suitable proportion of polyethyleneimine and aerogel can achieve better elastic recovery ability.

[0088] Compared with Example 1, Example 2, Example 3, Example 4, and Example 5, in the latter examples, due to the increase in the content of polyethyleneimine, the tensile properties and elastic recovery ability are improved, and the mechanical properties and thermal insulation properties can reach a better state.

[0089] It should be understood that the above embodiments are only used to illustrate the present invention and are not used to limit the scope of protection of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Claims

1. A method for preparing a polyethyleneimine-aerogel flexible film, characterized in that: The following steps are involved: S1. Prepare a polyethyleneimine aqueous solution and a hydrophilic aerogel aqueous solution respectively, mix the two solutions, and allow them to fully react under stirring; S2. After the reaction in step S1 is completed, alcohol, hydrochloric acid and a modifier are added to the mixed solution to allow it to react fully under stirring; S3, after the polyethyleneimine-aerogel solution in step S2 is washed and the solution becomes neutral, supercritical drying is performed to obtain a polyethyleneimine-aerogel flexible film.

2. The method for preparing a polyethyleneimine-aerogel flexible film according to claim 1, characterized in that: The concentration of the polyethyleneimine aqueous solution is 1wt%-4wt%; the concentration of the hydrophilic aerogel aqueous solution is 1wt%-8wt%.

3. The method for preparing a polyethyleneimine-aerogel flexible film according to claim 1, characterized in that: The hydrophilic aerogel includes hydrophilic silica aerogel or hydrophilic alumina aerogel.

4. The method for preparing a polyethyleneimine-aerogel flexible film according to claim 1, characterized in that: The mass ratio of the polyethyleneimine to the hydrophilic aerogel is 1:1-8.

5. The method for preparing a polyethyleneimine-aerogel flexible film according to claim 1, characterized in that: In step S1, the stirring time is 10 to 15 hours; the stirring rate is 100 to 300 rpm / min; and the reaction temperature is 40 to 70°C.

6. The method for preparing a polyethyleneimine-aerogel flexible film according to claim 1, characterized in that: In step S2, the alcohol includes methanol, ethanol, isopropanol or n-butanol; the modifier includes dimethyldiethoxysilane, hexamethyldisiloxane or hexamethyldisilazane.

7. The method for preparing a polyethyleneimine-aerogel flexible film according to claim 1, characterized in that: In step S2, the concentration of the hydrochloric acid is 4-12 mol / L.

8. The method for preparing a polyethyleneimine-aerogel flexible film according to claim 1, characterized in that: In step S2, the amount of alcohol added is 3wt% to 7wt% of the mixed solution in step S1; the amount of hydrochloric acid added is 9wt% to 10wt% of the mixed solution in step S1; the amount of modifier added is 5wt% to 10wt% of the mixed solution in step S1; the reaction temperature in step S2 is 60°C, and the reaction time is 2 to 5h.

9. The method for preparing a polyethyleneimine-aerogel flexible film according to claim 1, characterized in that: In step S3, the cleaning includes alkaline washing and water washing; the alkaline washing solution is a sodium hydroxide and potassium hydroxide aqueous solution with a concentration of 0.1% to 1%.

10. A polyethyleneimine-aerogel flexible film, characterized in that: The polyethyleneimine-aerogel flexible film is prepared by the method for preparing the polyethyleneimine-aerogel flexible film according to any one of claims 1-9.

Images