METHODS FOR PREPARING AEROGELS BY PLASTICIZING AND FOAMING WITH SOLVENTS

Abstract

The present invention provides a method for preparing an aerogel based on plasticizing and foaming with solvent, and the aerogel material is prepared through plasticization with solvent and generation of in-situ bubbles. The method solves the difficult problem that the non-polymer is difficult to realize thermoplastic foaming, and has wide applicability. In addition, a lot of foaming agents can be uses for this method, and this method is easy to implement, and does not require a special drying process, so that the industrialization development of the porous aerogel is greatly promote.

Claims

1. A method for preparing aerogel material, wherein the method is realized based on plasticizing and foaming with solvent and comprises: mixing a material to be foamed with a foaming agent precursor, assembling the resulted mixture into a macroscopical material; and placing the macroscopical material into a plastic solution to be plasticized and foamed, and then dried to obtain the aerogel material.

2. The method according to claim 1, wherein the plastic solution contains an initiator which initiates the foaming agent precursor to generate gas.

3. The method according to claim 1, wherein the foaming agent precursor is initiated by heating to generate gas.

4. A method for preparing aerogel material, wherein the method is realized based on plasticizing and foaming with solvent and comprises: assembling a material to be foamed into a macroscopical material; and placing the macroscopical material into a plastic solution containing, a foaming agent to be plasticized and foamed, and then dried to obtain the aerogel material.

5. The method according to claim 4, wherein the foaming agent comprises a spontaneous foaming agent and a reactive foaming agent, wherein the reactive foaming agent is a foaming agent that can generate gas by reacting with the material to be foamed, and the spontaneous foaming agent is a foaming agent that can be decomposed to generate gas.

6. The method according to claim 1, wherein the plastic solution is a plasticizer or a solution containing the plasticizer, and the plasticizer is a substance which can reduce the intermolecular force of the material to be foamed.

7. The method according to claim 1, wherein the material to be foamed comprises graphene, molybdenum disulfide, Mxene, cellulose, silver nanowire.

8. The method according to claim 7, wherein the material to be foamed is graphene oxide, the macroscopical material comprises graphene oxide film, graphene oxide fiber, graphene oxide non-woven fabric, graphene oxide aerogel, and the plastic solution is water, organic solvent, or a mixture of water and organic solvent.

9. The method according to claim 8, wherein the organic solvent is selected from the group consisting of dimethylformamide, dimethylacetamide, isopropanol, ethanol.

10. The method according to claim 8, wherein the graphene oxide has a size greater than or equal to 1 μm.

11. The method according to claim 8, wherein the method comprises mixing graphene oxide and a foaming agent precursor, forming a film, placing the film in the plastic solution for plasticizing and foaming and dried to obtain porous graphene aerogel material.

12. The method according to claim 11, wherein the foaming agent precursor is initiated to foam in the plastic solution by at least one of adding an initiator and heating; wherein the initiator initiates the foaming agent precursor to generate gas.

13. The method according to claim 8, wherein the method comprises placing the macroscopical material formed by stacking and assembling graphene oxide layers in the plastic solution containing the foaming agent to be plasticized and foamed, and dried to obtain porous graphene aerogel material.

14. The method according to claim 13, wherein the foaming agent comprises a spontaneous foaming agent and a reactive foaming agent, wherein the reactive foaming agent is a foaming agent that can generate gas by reacting with oxygen containing functional groups of the graphene oxide, and the spontaneous foaming agent is a foaming agent that can be decomposed to generate gas.

15. The method according to claim 14, wherein the reactive foaming agent comprises hydrazine hydrate, borohydride salt, and the spontaneous foaming agent comprises bicarbonate.

16. The method according to claim 1, wherein the drying comprises at least one of direct drying and solvent-displacement drying.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 shows a porous Mxenes aerogel material obtained from Example 1.

[0035] FIG. 2 shows a porous molybdenum disulfide aerogel material obtained from Example 2.

[0036] FIG. 3 shows a porous cellulose aerogel material obtained from Example 3.

[0037] FIG. 4 shows a porous graphene aerogel material obtained from Example 4.

[0038] FIG. 5 shows a porous graphene aerogel material obtained from Example 2.

[0039] FIG. 6 shows a porous Mxenes aerogel material obtained from Example 2.

[0040] FIG. 7 shows a dense macroscopical graphene oxide film material used in Example 7 and the resulting aerogel material.

[0041] FIG. 8 shows a dense macroscopical graphene oxide film material used in Example 8 and the resulting aerogel material.

[0042] FIG. 9 shows aerogels of different shapes obtained from Example 12.

[0043] FIG. 10 shows a large-scale aerogel obtained from Example 13.

[0044] FIG. 11 is a graph of the compression of the aerogel matetial obtained from Example 10 under different compressive deformations.

DESCRIPTION OF THE EMBODIMENTS

[0045] Hereinafter, the present invention will be further described with reference to examples, while the scope of the present invention is not limited thereto.

Example 1

[0046] An aqueous suspension of 5 mg/ml Mxenes was uniformly mixed with sodium bicarbonate (with a mass ratio of Mxnes to sodium bicarbonate being 1:1), dried to form a film, and then placed in 10% of hydrochloric acid to generate bubbles for 1 min, thereby obtaining porous Mxenes aerogel, as shown in FIG. 1, which has a wall thickness of 195 nm, an average pore diameter of 100 μm, and a density of 11 mg/cm.sup.3.

Example 2

[0047] An aqueous suspension of 5 mg/ml molybdenum disulfide was uniformly mixed with sodium bicarbonate (with a mass ratio of molybdenum disulfide to sodium bicarbonate being 1:1), dried to form a film, and then placed in 10% of hydrochloric acid to generate gas foaming for 5 minutes, thereby obtaining porous molybdenum disulfide aerogel, as shown in FIG. 2, which has a wall thickness of 105 nm, an average pore diameter of 87 μm, and a density of 15 mg/cm.sup.3.

Example 3

[0048] An aqueous suspension of 11 mg/ml bacterial cellulose was uniformly mixed with sodium carbonate (with a mass ratio of bacterial cellulose to sodium bicarbonate being: 1:5), dried to form a film, and then placed in 15% of hydrochloric acid to generate gas foaming for 1 min, thereby Obtaining porous cellulose aerogel, as shown in FIG. 3, which has a wall thickness of 360 nm, an average pore diameter of 230 μm, and a density of 35 mg/cm.sup.3.

Example 4

[0049] A suspension of 8 mg/nil graphene oxide was uniformly mixed with sulfuric acid which has an equal mass therewith, dried to form a film, and then placed in 10% of sodium bicarbonate solution to generate gas foaming for 1 min, thereby obtaining porous graphene aerogel, as shown in FIG. 4, which has a wall thickness of 50 nm, an average pore diameter of 310 μm, and a density of 12 mg/cm.sup.3.

Example 5

[0050] A suspension of 8 mg/nil graphene oxide was uniformly mixed with sulfuric acid which has an equal mass therewith, dried to form a film, and then placed in an aqueous solution containing 1% of sodium borohydride and DMF, wherein the volume ratio of DMF to water was 1:1, to generate gas foaming for 10 min, thereby obtaining porous graphene aerogel, as shown in FIG. 5, which has a wall thickness of 30 nm, an average pore diameter of 350 μm, and a density of 11 mg/cm.sup.3.

Example 6

[0051] An aqueous suspension of 5 mg/ml Mxenes was uniformly mixed with sodium bicarbonate (with a mass ratio of Mxnes to sodium bicarbonate being 1:1) dried to form a film, and then placed in water and heated at 40 Celsius degrees to generate bubbles for 1 min, thereby obtaining porous Mxenes aerogel, as shown in FIG. 6, which has a wall thickness of 207 nm, an average pore diameter of 122 μm, and a density of 25 mg/cm.sup.3.

Example 7

[0052] A suspension of 5 mg/ml graphene oxide (GO, available from Hangzhou Gaoxi Technology Co., LTD., with a size of 500 to 800 nm) was cast to obtain a graphene oxide film with a thickness of about 20 μm, which was cut into a disc and then placed in 10 wt % of aqueous solution of hydrazine hydrate for 5 minutes, thereby obtaining graphene aerogel having a height of about 8 mm.

[0053] The foamed graphene aerogel was soaked in water for 15 min to replace the foaming agent solution, and then dried under atmospheric pressure to remove the volatile solvent, thereby obtaining porous graphene aerogel with a density of about 5 mg/cm.sup.3.

[0054] Compression test was carried out on the prepared aerogel using a compression tester, and it was found that the residual stress of the prepared aerogel after 10000 times of 90% strain compression was 85% of the initial stress and the plastic deformation was 15%.

Example 8

[0055] A suspension of 5 mg/ml graphene oxide (GO, available from Hangzhou Gaoxi Technology Co., LTD., with a size of 50 to 100 μm) was suffered from wet spinning to obtain a graphene oxide fiber with a diameter of 31.4 μm, which was then placed in 85 wt % of aqueous solution of hydrazine hydrate for 60 minutes, thereby obtaining highly entangled graphene fiber aerogel.

[0056] The foamed graphene aerogel was soaked in the volatile solvent, i.e., n-hexane, for 15 min to replace the foaming agent solution, and then directly dried to remove the volatile solvent, thereby obtaining porous graphene aerogel with a density of about 3 mg/cm.sup.3.

[0057] Tensile test was carried out on the prepared aerogel using a tensile tester, and it was found that the prepared aerogel has an elongation at break of about 6%, and can be repeatedly tensed under 5% strain for 1000 times without breaking.

Example 9

[0058] At −10 Celsius degrees, 5 g of potassium permanganate was slowly added into 40 ml of concentrated sulfuric acid which was being rapidly stirred, after the mixture was fully dissolved, 1 g of graphite with particle size of 300 μm was added therein and was slowly stirred at 60 r/min for 2 h, and then the stilling was stopped and the reaction was kept at a low temperature of 10 Celsius degrees for 18 h to obtain a broad distribution of graphite oxide crystal; the resulted solution was diluted with concentrated sulfuric acid and filtered with a titanium alloy mesh screen having a pore size of 150 μm to obtain the graphite oxide crystal (with the solution retrieved), which was then slowly poured into ice water that was being rapidly stirred and had a volume of 10 times the filtered product, and then the mixture was stood for 2 hours, and was slowly added with H.sub.2O.sub.2 to remove excess potassium permanganate, and was added with appropriate amount of hydrochloric acid until the flocculent graphite oxide disappeared, and was then filtered by titanium alloy mesh screen to obtain graphite oxide crystal plates; the graphite oxide crystal plates were then shaken and washed slowly with a shaker to obtain a large piece of graphene oxide without fragment, which has been test with an average size of 10 μm and a distribution coefficient of 0.5, and C/O ratio of 1.7.

[0059] A suspension of 10 mg/nil graphene oxide was prepared and was suffered from suction filtration to prepare a graphene oxide non-woven fabric with a thickness of 20 μm, which was then placed in an aqueous solution of 100 mg/mL ammonium bicarbonate for reaction for 20 minutes at 60 Celsius degrees, thereby obtaining graphene aerogel having a height of about 7 mm.

[0060] The foamed graphene aerogel was soaked in the volatile solvent, cyclohexane, for 15 min to replace the foaming agent solution, and then directly dried to remove the volatile solvent, thereby obtaining porous grapheme aerogel with a density of about 2.4 mg/cm.sup.3.

[0061] Compression test was carried out on the prepared aerogel using a compression tester, and it was found that the residual stress of the prepared aerogel after 50000 times of 90% strain compression was 95% of the initial stress and the plastic deformation was 5%.

Example 10

[0062] At −10 Celsius degrees, 5 g of potassium permanganate was slowly added into 30 ml of concentrated sulfuric acid which was being rapidly stirred, after the mixture was fully dissolved, 1 g of graphite with particle size of 2 mm was added therein and was slowly stirred at 60 r/min for 2 h, and then the stirring was stopped and the reaction was kept at a low temperature of 20 Celsius degrees for 48 h to obtain a broad distribution of graphite oxide crystal; the resulted solution was diluted with concentrated sulfuric acid and filtered with a titanium alloy mesh screen having a pore size of 150 to obtain the graphite oxide crystal (with the solution retrieved), which was then slowly poured into ice water that was being rapidly stirred and had a volume of 10 times the filtered product, and then the mixture was stood for 2 hours, and was slowly added with H.sub.7O.sub.2 to remove excess potassium permanganate, and was added with appropriate amount of hydrochloric acid until the flocculent graphite oxide disappeared, and was then filtered by titanium ahoy mesh screen to obtain graphite oxide crystal plates; the graphite oxide crystal plates were then shaken and washed slowly with a shaker to obtain a large piece of graphene oxide without fragment, which has been test with an average size of 108 μm and a distribution coefficient of 0.2, and C/O ratio of 3.1.

[0063] A suspension of 10 mg/mi graphene oxide was prepared and was cast to prepare a graphene oxide film with a thickness of 20 μm, which was then placed in an aqueous solution of 10 mg/mL sodium borohydride for reaction for 20 minutes, thereby obtaining graphene aerogel having a height of about 6.5 mm.

[0064] The foamed graphene aerogel was soaked in the volatile solvent, i.e., acetone, for 15 min to replace the foaming agent solution, and then directly dried to remove the volatile solvent, thereby obtaining a porous graphene aerogel with a density of about 5.9 mg/cm.sup.3.

[0065] Compression test was carried out on the prepared aerogel using a compression tester, and it was found that the residual stress of the prepared aerogel after 10000 times of 90% strain compression was 98% of the initial stress and the plastic deformation was 2%.

Example 11

[0066] At −10 Celsius degrees, 5 g of potassium permanganate was slowly added into 30 ml of concentrated sulfuric acid which was being rapidly stirred, after the mixture was fully dissolved, 1 g of graphite with particle size of 2 mm was added therein and was slowly stirred at 60 r/min for 2 h, and then the stirring was stopped and the reaction was kept at a temperature of 20 Celsius degrees for 6 h to obtain graphene oxide, which has been test with an average size of 47 μm and a distribution coefficient of 0.5, and (70 ratio of 4.2.

[0067] A suspension of 10 mg/ml graphene oxide was prepared, and was cast to prepare a graphene oxide film with a thickness of about 20 μm.

[0068] Sodium borohydride with a mass/volume ratio of 80 mg/ml was added to a mixture of water and dimethylformamide with a volume ratio of 1:1, thereby obtaining foaming agent solution.

[0069] The graphene oxide film was placed in the foaming agent solution for 20 minutes, thereby obtaining graphene aerogel having a height of about 6.5 mm.

[0070] The foamed graphene aerogel was directly dried to remove the volatile solvent to obtain porous graphene aerogel with a density of about 5.9 mg/cm.sup.3.

[0071] Compression test was carried out on the prepared aerogel using a compression tester, and it was found that the residual stress of the prepared aerogel after 10000 times of 90% strain compression was 97% of the initial stress and the plastic deformation was 3%.

Example 12

[0072] The materials and method used in this example were the same as those in Example 7, and this example differs from Example 7 in that the graphene oxide film was cut into different shapes, such as the shape of rabbit, bear, dolphin, and was foamed by liquid to obtain highly porous aerogel with special shapes, with a density of about 5-6 mg/cm.sup.3.

Example 13

[0073] The materials and method used in this example were the same as those in Example 7, and this example differs from Example 7 in that a sheet of graphene oxide film having a size of 25*25 cm was prepared, and was foamed by liquid to obtain highly porous and large-scale graphene aerogel, with a density of about 5 mg/cm.sup.3. As can be seen that, the plasticizing and foaming method disclosed herein is applicable for large-scale preparation.

Example 14

[0074] A suspension of graphene oxide, having a size ranging from 20 to 30 μm, a carbon to oxygen ratio of 2.5, and a concentration of 5 mg/ml, available from Hangzhou Gaoxi Co., LTD., was cast to obtain a graphene oxide film with a thickness of about 20 μm, which was cut into a disc and then placed in a solution of 85% hydrazine hydrate for one hour to obtain graphene aerogel having a height of about 8.1 mm. The graphene aerogel was soaked in ethanol to replace the foaming agent solution and then dried at 60 Celsius degrees to remove the ethanol, and was treated at a high temperature of 1600 Celsius degrees for 1 h, thereby obtaining graphene aerogel with a density of 3 mg/cm.sup.3, of 0.2, and an electromagnetic shielding effectiveness of 110 dB at 5 mm.

Example 15

[0075] A suspension of graphene oxide, having a size ranging from 80 to 100 μm, a carbon to oxygen ratio of 2.35, and a concentration of 10 mg/ml, available from Hangzhou Gaoxi Co., LTD., was cast to obtain a graphene oxide film with a thickness of about 50 which was cut into a disc and then placed in an aqueous solution of 100 mg/mL ammonium bicarbonate for a while to obtain graphene aerogel having a height of about 12.6 mm. The grapheme aerogel was soaked in isopropanol to replace the foaming agent solution and then dried at 60 Celsius degrees to remove the isopropanol, and was treated at a high temperature of 1600 Celsius degrees for 1 h, thereby obtaining graphene aerogel with a density of 5 mg/cm.sup.3, I.sub.D/I.sub.G of 0.15, and an electromagnetic shielding effectiveness of 70 dB at 5 mm.

Example 16

[0076] A suspension of graphene oxide, having a size ranging from 100 to 200 μm, a carbon to oxygen ratio of 2.14, and a concentration of 10 mg/ml, available from Hangzhou Gaoxi Co., LTD., was suffered from suction filtration to obtain a graphene oxide film with a thickness of about 30 μm, which was cut into a disc and then placed in an aqueous solution of 100 mg/Ml, ammonium bicarbonate for a while to obtain graphene aerogel having a height of about 8.5 mm. The graphene aerogel was soaked in isopropanol to replace the foaming agent solution and then dried at 60 Celsius degrees to remove the isopropanol, and was treated at a high temperature of 1000 Celsius degrees for 1 h, thereby obtaining graphene aerogel with a density of 5.3 mg/cm.sup.3, I.sub.D/I.sub.G of 0.1, and an electromagnetic shielding effectiveness of 102 dB at 5 mm.

Comparative Example 1

[0077] A suspension of graphene oxide, having a size ranging from 20 to 30 μm, a carbon to oxygen ratio of 2.5, and a concentration of 5 mg/ml, available from Hangzhou Gaoxi Co., LTD., was cast to obtain a graphene oxide film with a thickness of about 20 μm, which was cut into a disc (the same as Example 14) and was directly treated at a high temperature of 1600 Celsius degrees for 1 h, thereby obtaining porous graphene film with a density of 100 mg/cms, I.sub.D/I.sub.G of 0.2, and an electromagnetic shielding effectiveness of 20 dB.

Comparative Example 2

[0078] Ammonium bicarbonate was added into a suspension of graphene oxide, having a size ranging from 80 to 100 μm, a carbon to oxygen ratio of 2.35, and a concentration of 10 mg/ml, available from Hangzhou Gaoxi Co., LTD., and the resulted mixture was cast to obtain a graphene oxide film with a thickness of about 50μm, which was cut into a disc and subjected to decomposition of the ammonium bicarbonate at 200 Celsius degrees to foam the graphene film. The resulted foamed material has a large number of discrete pores.