A method for preparing amino hyperbranched siloxane and modified polyimide aerogel material

Abstract

The invention discloses a kind of preparation method of amino hyperbranched siloxane and its modified polyimide aerogel material.First, alkoxysilane X with amino active functional group, alkoxysilane Y of inactive functional group and water are carried out autocatalytic controlled hydrolysis condensation under sub-stoichiometric ratio, obtain multifunctional group (such as other active groups, alkoxyl group, amino) amino hyperbranched siloxane liquid (HPSi NH2) with controllable amino content, then using HPSi NH2 as cross-linking agent and anhydride-terminated polyamic acid solution reaction to obtain functionalized polyamic acid, which is stirred with tertiary amine and deionized water to obtain functionalized polyamic acid wet gel, which is passed through freeze drying, high temperature imidization treatment to obtain amino hyperbranched siloxane modified polyimide aerogel material. This material has excellent flexibility, resilience, heat resistance and flame retardancy, and can be applied to aerospace, communication, catalysis and filtration fields.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and more specifically, relates to a preparation method of amino hyperbranched siloxane and modified polyimide aerogel material thereof. Background Art

[0002] Silicone resins exhibit excellent properties such as high and low temperature resistance, weather resistance, aging resistance, and electrical insulation. They have been widely used in aerospace, electronics, light industry, and other fields, becoming an essential new polymer material in the national economy. However, due to their highly cross-linked structure and the interaction between hydroxyl groups, traditional silicone resins have high viscosity, making them difficult to apply. Hyperbranched polymers, derivatives of dendritic polymers, offer advantages such as simple synthesis, high functional group density, and low viscosity. However, the hyperbranched siloxanes synthesized today have a single active group and cannot be adjusted according to usage conditions, resulting in a cumbersome preparation process.

[0003] Polyimide aerogels have excellent mechanical strength, high-temperature resistance, and radiation resistance, leading to a growing research interest in these materials in recent years. Freeze-drying has become a mainstream method for preparing polyimide aerogels due to its simplicity and lack of organic solvents. However, the polyimide aerogels prepared by this method exhibit poor resilience and low mechanical strength due to the lack of chemical crosslinking between linear polyamic acids. Furthermore, the polyimide aerogels themselves lack functionality, limiting their further development. Summary of the Invention

[0004] In view of the above-mentioned problems existing in the prior art, the technical problem to be solved by the present invention is to provide an amino-hyperbranched siloxane, which is liquid at room temperature and contains a large amount of amino, alkoxy and other active groups. At the same time, the content of amino and alkoxy groups can be regulated, and the types of other active groups can be selected according to the use requirements. Another technical problem to be solved by the present invention is to provide a method for preparing an amino-hyperbranched siloxane-modified polyimide aerogel material, which can regulate the content of amino and alkoxy groups in the amino-hyperbranched siloxane and thus regulate the performance of the obtained material. The last technical problem to be solved by the present invention is to provide a material obtained by the preparation method of the amino-hyperbranched siloxane-modified polyimide aerogel material, which has excellent flexibility, resilience, small volume shrinkage, heat resistance and excellent flame retardancy.

[0005] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0006] 1) an alkoxysilane X having an amino-active functional group and an alkoxysilane Y having an inactive functional group are mixed and stirred in an organic solvent at 0-80° C. for 1-4 hours; water in a stoichiometric ratio is slowly added dropwise to the system and reacted at 0-80° C. for 1-24 hours; and finally, the solvent is removed by reduced pressure distillation at 40-90° C. and a pressure of -0.1-0 MPa for 1-3 hours to obtain a hyperbranched aminosiloxane (HPSi-NH2);

[0007] 2) reacting a dianhydride compound and a diamine compound in an organic solvent at a reaction temperature of -10 to 25° C. for 2 to 12 hours; then adding HPSi-NH2 to the reaction system and reacting at -10 to 25° C. for 1 to 8 hours to obtain a functionalized siloxane-modified polyamic acid solution;

[0008] 3) adding a tertiary amine to the functionalized siloxane-modified polyamic acid solution, and after the reaction is complete, slowly adding deionized water to the system to fully precipitate, filtering the precipitate, and vacuum drying to obtain a functionalized polyamic acid powder;

[0009] 4) stirring the functionalized polyamic acid powder obtained in step 3), a tertiary amine, and deionized water at 0-80° C. for 2-24 hours to obtain a functionalized polyamic acid wet gel; then freezing the wet gel at -197--20° C. for 1-24 hours, and freeze-drying the gel to obtain a functionalized polyamic acid xerogel;

[0010] 5) The multifunctional polyamic acid xerogel obtained in step 4) is subjected to high-temperature imidization in an N2 or Ar atmosphere at a temperature of 150-300°C for 2-12 hours to obtain an amino hyperbranched siloxane-modified polyimide aerogel material.

[0011] The molar ratio of the alkoxysilane X with an amino active functional group to the alkoxysilane Y with an inactive functional group is 1:0.1-9; the molar ratio of X+Y to water is 1:0.5-1.5; the molar ratio of the dianhydride compound to the diamino compound is 1:0.5-0.95; and the molar ratio of the dianhydride compound to HPSi-NH2 is 1:0.05-0.5.

[0012] Furthermore, in step 1), the alkoxysilane X with an amino-active functional group is selected from one or more of 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, p-aminophenyltrimethoxysilane, p-aminophenyltriethoxysilane, anilinemethyltriethoxysilane, and anilinemethyltrimethoxysilane, and its specific general formula is as follows:

[0013]

[0014] The alkoxysilane Y of the non-active functional group is selected from one or more of methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, octyltrimethoxysilane, octyltriethoxysilane, chloromethyltrimethoxysilane, chloromethyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 1-(trimethoxysilyl)naphthalene, 1-(triethoxysilyl)naphthalene, p-chlorophenyltrimethoxysilane, and p-chlorophenyltriethoxysilane, and its specific general formula is as follows:

[0015]

[0016] Furthermore, in step 1), the organic solvent is selected from one or more of anhydrous methanol, anhydrous ethanol, anhydrous n-butanol, anhydrous tetrahydrofuran, and anhydrous acetone; the content of the organic solvent is 40-80 wt%; the stirring temperature is 0-80° C.; and the stirring reaction time is 1-4 h.

[0017] Furthermore, the content of the organic solvent is 50 to 70 wt%.

[0018] Furthermore, in step 1), the molar ratio of the alkoxysilane X with an amino active functional group to the alkoxysilane Y with an inactive functional group is 1:0.1-9; in step 1), the molar ratio of X+Y to water is 1:0.5-1.5; the reaction temperature is 0-80°C; and the reaction time is 1-24h.

[0019] Furthermore, the molar ratio of X+Y to water is 3:1-1.3; the reaction temperature is 50-70° C.; and the reaction time is 8-12 h.

[0020] Furthermore, the specific general formula of HPSi-NH2 obtained in step 1) is as follows:

[0021]

[0022] Furthermore, in step 2), the dianhydride compound is selected from one or more of pyromellitic dianhydride, 3,3',4,4'-diphenylsulfone tetracarboxylic dianhydride, 2,3,3',4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-diphenyl ether tetracarboxylic dianhydride, 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 3,3',4,4'-biphenyltetracarboxylic dianhydride, and its specific general formula is as follows:

[0023]

[0024] The diamine compound is selected from one or more of 4,4'-diaminodiphenyl ether, 2,6-diaminopyridine, 4,4'-diaminodiphenyl sulfone, m-phenylenediamine, p-phenylenediamine, 4,4'-bis(3-aminophenoxy)biphenyl, 2,5-bis(4-aminophenyl)pyridine, bisphenol A diether diamine, and 1,3-bis(3-aminopropyl)tetramethyldisiloxane.

[0025] Furthermore, in step 2), the organic polar solvent is selected from one or more of N-methylpyrrolidone, N-ethylpyrrolidone, N,N-dimethylformamide, and N,N-dimethylacetamide; the content of the organic solvent is 50 to 90 wt%; the reaction temperature is -10 to 25°C; and the reaction time is 5 to 12 h.

[0026] Furthermore, the content of the organic solvent is 75-85 wt %; the reaction temperature is 0-10° C.; and the reaction time is 8-10 h.

[0027] Furthermore, the molar ratio of the dianhydride compound to the diamino compound is 1:0.5-0.95; the reaction time is 2-12 hours; and the reaction temperature is -10-25°C.

[0028] Furthermore, the molar ratio of the dianhydride compound to HPSi-NH2 is 1:0.05-0.5; the reaction temperature is -10-25°C, and the reaction time is 1-8h.

[0029] Furthermore, the reaction temperature is -5 to 10°C, and the reaction time is 2 to 4 hours.

[0030] Furthermore, in step 3), the tertiary amine is one or more of triethylamine, trimethylamine, N,N-dimethylaniline, N,N-dimethylcyclopentylamine, N-methyl-N-ethyl-p-methylaniline, and N,N-dimethylbenzylamine; and the mass ratio of the small molecule tertiary amine to the polyamic acid is 0.1 to 0.7:1.

[0031] Furthermore, the mass ratio of tertiary amine to polyamic acid is 0.4 to 0.6:1

[0032] Furthermore, in step 4), the mass ratio of tertiary amine to polyamic acid is 0.4-0.9:1; the content of deionized water is 50-90 wt%; the mixing temperature is 0-80° C.; and the mixing time is 2-24 h.

[0033] Furthermore, the mass ratio of tertiary amine to polyamic acid is 0.4-0.6:1; the content of deionized water is 60-80 wt%; the mixing temperature is 25-60° C.; and the mixing time is 6-12 hours.

[0034] Furthermore, in step 4), the polyamic acid wet gel is frozen at a temperature of -197 to -20°C and the freezing time is 1 to 24 hours.

[0035] Furthermore, in step 5), the thermal imidization temperature of the polyimide acid xerogel is 150-300° C.; and the thermal imidization time is 2-12 hours.

[0036] The amino hyperbranched siloxane modified polyimide aerogel material prepared by the above preparation method.

[0037] Compared with the prior art, the present invention has the following beneficial effects:

[0038] The present invention subjects an alkoxysilane X with an amino-active functional group, an alkoxysilane Y with an inactive functional group, and water to autocatalytic controlled hydrolysis and condensation at a substoichiometric ratio to obtain an amino-hyperbranched siloxane liquid (HPSi-NH2) with a controllable amino content and multiple functional groups (such as other active groups, alkoxy groups, and amino groups). The liquid is liquid at room temperature and contains a large number of amino groups, alkoxy groups, and other active groups. The types of other active groups can be selected according to usage requirements. The amino-hyperbranched siloxane-modified polyimide aerogel material provided by the present invention has superior flexibility and resilience compared to traditional polyimide aerogel materials, and the functional groups can be regulated according to usage conditions. The prepared amino-hyperbranched siloxane-modified polyimide aerogel material also has low volume shrinkage, excellent heat resistance, and flame retardancy, and can be applied to aerospace, communications, catalysis, and filtration fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 The present invention is a flow chart of a preparation method of amino hyperbranched siloxane and modified polyimide aerogel material;

[0040] Figure 2 This is a physical picture of HPSi-NH2 in Example 1;

[0041] Figure 3 It is an infrared spectrum diagram of the preparation method of amino hyperbranched siloxane and its modified polyimide aerogel material;

[0042] Figure 4 This is a scanning electron microscope image of the preparation method of amino hyperbranched siloxane and its modified polyimide aerogel material;

[0043] Figure 5 This is a graph showing the thermal stability (in air and nitrogen atmosphere) of the preparation method of amino hyperbranched siloxane and its modified polyimide aerogel material;

[0044] Figure 6 It is a cyclic compression diagram of the preparation method of amino hyperbranched siloxane and modified polyimide aerogel material under 80% strain;

[0045] Figure 7 This is a compressed physical picture of amino hyperbranched siloxane and its modified polyimide aerogel materials. DETAILED DESCRIPTION

[0046] The present invention will be further described below with reference to specific examples. These examples are intended to illustrate the present invention only and are not intended to limit the scope of the present invention. Unless otherwise specified, all experimental methods used in the following examples are conventional methods. All raw materials used can be obtained from public commercial sources unless otherwise specified.

[0047] Example 1

[0048] A preparation method of amino hyperbranched siloxane and its modified polyimide aerogel material, such as Figure 1 As shown, the following steps are included:

[0049] 1) In a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, 24.37 g (0.1 mol) of phenyltrimethoxysiloxane, 221.37 g (1 mol) of aminotrimethoxysiloxane, and 105.32 g (30 wt%) of anhydrous methanol were added and stirred at 0°C for 4 h to mix uniformly; 9.9 g (0.55 mol) of water was slowly added dropwise to the reaction system to react at 0°C for 24 h; the solvent was removed by reduced pressure distillation at -0.1 MPa at 40°C for 3 h to obtain HPSi-NH2.

[0050] 2) In a 1000 mL three-necked flask equipped with a mechanical stirrer and a condenser, 19.02 g (0.095 mol) of 4,4'-diaminoanisole, 32.22 g (0.1 mol) of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 461.16 g of N,N-dimethylformamide (the organic solvent content is 90 wt%) were added, and the mixture was reacted at -10°C for 12 h; 0.005 mol of HPSi-NH2 was added to the reaction system, and the mixture was reacted at -10°C for 8 h to obtain a phenylsiloxane-modified polyamic acid solution.

[0051] 3) 5.12 g of triethylamine (the mass ratio of triethylamine to polyamic acid is 0.1:1) was added to the phenylsiloxane-modified polyamic acid solution obtained in step 2). After the reaction was complete, deionized water was slowly added to the system to fully precipitate. The precipitate was filtered and vacuum dried to obtain a phenyl-functionalized polyamic acid powder.

[0052] 4) The phenyl-functionalized polyamic acid powder obtained in step 3) was stirred at 0°C for 24 hours with 46.112 g of triethylamine (the mass ratio of triethylamine to polyamic acid powder was 0.9:1) and 102.48 g of deionized water (50 wt % deionized water) to obtain a phenyl-functionalized polyamic acid wet gel. The wet gel was frozen at -197°C for 1 hour and then freeze-dried to obtain a phenyl-functionalized polyamic acid xerogel.

[0053] 5) The phenyl-functionalized polyamic acid xerogel obtained in step 4) was subjected to high-temperature imidization at 150° C. in a N 2 atmosphere for 12 h to obtain an amino-hyperbranched siloxane-modified polyimide aerogel material.

[0054] The basic properties of HPSi-NH2 prepared in Example 1 are as follows:

[0055] Viscosity: 1500cps

[0056] Amino content: 4.89mmol / g

[0057] The basic properties of the prepared amino hyperbranched siloxane and its modified polyimide aerogel material are as follows:

[0058] Density: 0.063g / cm 3

[0059] Porosity: 92%

[0060] Compressive strength at 50% compressive strain: 23 kPa

[0061] Example 2

[0062] A preparation method of amino hyperbranched siloxane and its modified polyimide aerogel material, such as Figure 1 As shown, the following steps are included:

[0063] 1) In a 1000 mL three-necked flask equipped with a mechanical stirrer and a condenser, 210.97 g (0.9 mol) of octyltrimethoxysilane, 21.33 g (0.1 mol) of p-aminophenyltrimethoxysilane, and 929.2 g (80 wt%) of anhydrous ethanol were added and stirred at 80° C. for 1 h to mix uniformly; 27 g (1.5 mol) of water was slowly added dropwise to the reaction system to react at a reaction temperature of 80° C. for 1 h; the solvent was removed by reduced pressure distillation at 80° C. and a pressure of -0.05 MPa for 1 h to obtain HPSi-NH2.

[0064] 2) In a 250 mL three-necked flask equipped with a mechanical stirrer and a condenser, 12.42 g (0.05 mol) of 4,4'-diaminodiphenyl sulfone, 21.82 g (0.1 mol) of pyromellitic anhydride, and 34.24 g of N,N-diethylformamide (the organic solvent content was 50 wt%) were added and reacted at 25°C for 2 h. 0.05 mol of HPSi-NH2 was added to the system and reacted at 25°C for 1 h to obtain an octylsiloxane-modified polyamic acid solution.

[0065] 3) 23.97 g of trimethylamine (the mass ratio of trimethylamine to polyamic acid is 0.7:1) is added to the octylsiloxane-modified polyamic acid solution obtained in step 2). After the reaction is complete, deionized water is slowly added to the system to fully precipitate. The precipitate is filtered and vacuum-dried to obtain an octyl-functionalized polyamic acid powder.

[0066] 4) The octyl-functionalized polyamic acid powder obtained in step 3) was stirred at 80° C. for 2 hours with 10.27 g of trimethylamine (the mass ratio of trimethylamine to polyamic acid powder was 0.3:1) and 616.32 g of deionized water (90 wt % deionized water) to obtain an octyl-functionalized polyamic acid wet gel. The octyl-functionalized polyamic acid wet gel was frozen at −20° C. for 24 hours and then freeze-dried to obtain an octyl-functionalized polyamic acid xerogel.

[0067] 6) The octyl-functionalized polyamic acid xerogel obtained in step 5) was subjected to high-temperature imidization at 300° C. in an Ar atmosphere for 2 h to obtain an amino-hyperbranched siloxane-modified polyimide aerogel material.

[0068] The basic properties of HPSi-NH2 prepared in Example 2 are as follows:

[0069] Viscosity: 3000cps

[0070] Amino content: 0.824mmol / g

[0071] The basic properties of the prepared amino hyperbranched siloxane modified polyimide aerogel material are as follows:

[0072] Density: 0.0521g / cm 3

[0073] Porosity: 89%

[0074] Example 3

[0075] A method for preparing an amino-hyperbranched siloxane-modified polyimide aerogel material comprises the following steps:

[0076] 1) In a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, 99.15 g (0.5 mol) of phenyltrimethoxysiloxane, 111.18 g (0.5 mol) of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and 140.22 g (40 wt%) of anhydrous tetrahydrofuran were added and stirred at room temperature for 2 h to mix uniformly; 18 g (1 mol) of water was slowly added dropwise to the reaction system to react at a reaction temperature of 50° C. for 12 h; the solvent was removed by reduced pressure distillation at 50° C. and a pressure of 0 MPa for 2 h to obtain HPSi-NH2.

[0077] 2) In a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, 8.73 g (0.08 mol) of 2,6-diaminopyridine, 31.02 g (0.1 mol) of 3,3',4,4'-diphenylether tetracarboxylic dianhydride, and 119.25 g of N-methylpyrrolidone (the organic solvent content was 75 wt%) were added and reacted at 10°C for 8 h. 0.02 mol of HPSi-NH2 was added to the system and reacted at 10°C for 6 h to obtain a phenylsiloxane-modified polyamic acid solution.

[0078] 3) 15.9 g of N,N-dimethylaniline (the mass ratio of N,N-dimethylaniline to polyamic acid is 0.4:1) is added to the phenylsiloxane-modified polyamic acid solution obtained in step 2). After the reaction is complete, deionized water is slowly added to the system to fully precipitate, and the precipitate is filtered and vacuum-dried to obtain a phenyl-functionalized polyamic acid powder.

[0079] 4) stirring the phenyl-functionalized polyamic acid powder obtained in step 3) with 23.85 g of N,N-dimethylaniline (the mass ratio of N,N-dimethylaniline to polyamic acid powder is 0.6:1) and 145.75 g of deionized water (the content of deionized water is 60 wt%) at 25° C. for 12 h to obtain a phenyl-functionalized polyamic acid wet gel, freezing the wet gel at −10° C. for 18 h, and then freeze-drying the gel to obtain a phenyl-functionalized polyamic acid xerogel;

[0080] 5) The phenyl-functionalized polyamic acid xerogel obtained in step 5) was subjected to high-temperature imidization at 270° C. in an Ar atmosphere for 8 h to obtain an amino-hyperbranched siloxane-modified polyimide aerogel material.

[0081] The basic properties of HPSi-NH2 prepared in Example 3 are as follows:

[0082] Viscosity: 2700cps

[0083] Amino content: 3.68mmol / g

[0084] The basic properties of the prepared amino hyperbranched siloxane modified polyimide aerogel material are as follows:

[0085] Density: 0.0368g / cm 3

[0086] Porosity: 94.2%

[0087] Thermal conductivity: 0.0279W / m·K

[0088] Example 4

[0089] A method for preparing an amino-hyperbranched siloxane-modified polyimide aerogel material comprises the following steps:

[0090] 1) In a 1000 mL three-necked flask equipped with a mechanical stirrer and a condenser, 120.4 g (0.5 mol) of 3-chloropropyltriethoxysilane, 22.14 g (0.1 mol) of aminopropyltriethoxysilane, and 280.72 g (70 wt%) of anhydrous acetone were added and stirred at 40° C. for 2 h to mix uniformly; 14.04 g (0.78 mol) of water was slowly added dropwise to the reaction system to react at a reaction temperature of 70° C. for 8 h; the solvent was removed by reduced pressure distillation at 50° C. and a pressure of -0.03 MPa for 2 h to obtain HPSi-NH2.

[0091] 2) In a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, 24.63 g (0.06 mol) of bisphenol A diether diamine, 29.42 g (0.1 mol) of 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 306.28 g of N-ethylpyrrolidone (the organic solvent content was 85 wt%) were added and reacted at 10°C for 8 hours. 0.04 mol of HPSi-NH2 was added to the system and reacted at 10°C for 6 hours to obtain a chlorosiloxane-modified polyamic acid solution.

[0092] 3) 32.43 g of N,N-dimethylbenzylamine (the mass ratio of N,N-dimethylbenzylamine to polyamic acid is 0.6:1) is added to the chlorine-containing siloxane-modified polyamic acid solution obtained in step 2). After the reaction is complete, deionized water is slowly added to the system to fully precipitate. The precipitate is filtered and vacuum-dried to obtain a chlorine-functionalized polyamic acid powder.

[0093] 4) The chlorine-functionalized polyamic acid powder obtained in step 3) was stirred at 60° C. for 6 hours with 21.64 g of N,N-dimethylbenzylamine (the mass ratio of N,N-dimethylbenzylamine to polyamic acid powder was 0.4:1) and 486.45 g of deionized water (80 wt % deionized water) to obtain a chlorine-functionalized polyamic acid wet gel. The wet gel was frozen at −10° C. for 18 hours and then freeze-dried to obtain a chlorine-functionalized polyamic acid xerogel.

[0094] 5) The chlorine-functionalized polyamic acid xerogel obtained in step 4) was subjected to high-temperature imidization in an Ar atmosphere at a temperature of 270° C. for 8 h to obtain an amino hyperbranched siloxane-modified polyimide aerogel material.

[0095] The basic properties of the amino hyperbranched siloxane prepared in Test Example 4 are as follows:

[0096] Viscosity: 3500cps

[0097] Amino content: 1.598mmol / g

[0098] The basic properties of chlorine-containing amino hyperbranched siloxane modified polyimide aerogel materials are as follows:

[0099] Density: 0.0443 g / cm -3

[0100] Porosity: 93.2%

[0101] Specific surface area: 12.3m 2 / g

[0102] Example 5

[0103] The HPSi and amino hyperbranched siloxane modified polyimide aerogel materials prepared in the above examples were chemically characterized and tested for their properties. Figure 2-7 As shown:

[0104] Figure 2 This is a physical picture of HPSi-NH2 in Example 1. It can be seen from the figure that the HPSi-NH2 is liquid at room temperature and has a low viscosity.

[0105] Figure 3 This is the infrared spectrum of the amino hyperbranched siloxane modified polyimide aerogel material in Example 1. It can be seen from the figure that at 800 cm -1 The Si-O-Si bending vibration peak appeared at 1787cm -1 、1720cm -1 、1375cm -1 The C=O symmetric and antisymmetric stretching vibration peaks on the imine ring and the CN stretching vibration peak on the imine ring appeared at the bottom, respectively, indicating that the amino hyperbranched siloxane modified polyimide aerogel material.

[0106] Figure 4 This is a scanning electron microscope image of the amino-hyperbranched siloxane-modified polyimide aerogel material in Example 3. It can be seen from the image that the aerogel material exhibits a layered porous structure with an interlayer spacing of approximately 10 μm. It is this unique layered structure that gives the amino-hyperbranched siloxane-modified polyimide aerogel material excellent rebound performance.

[0107] Figure 5 The thermal stability diagram of amino hyperbranched siloxane modified polyimide aerogel material in Example 3 is (a) air atmosphere (b) nitrogen atmosphere. It can be seen from the figure that the T of the multifunctional flexible polyimide aerogel material in air and nitrogen atmosphere is 10％ They are 434°C and 459°C respectively, which are better than other polymer aerogel materials (such as polyimide aerogel, polystyrene aerogel, polypyrrolidone aerogel, etc.).

[0108] Figure 6 Example 4 is a cyclic compression diagram of an amino-hyperbranched siloxane-modified polyimide aerogel material at 80% strain. From the diagram, it can be seen that the compressive strength of the aerogel material at 80% strain is 21 kPa. At the same time, it can still maintain a high compressive strength after 10 compression cycles, which means that the aerogel material has excellent mechanical strength.

[0109] Figure 7 This is a compressed physical picture of the amino hyperbranched siloxane and its modified polyimide aerogel material in Example 4. It can be seen from the figure that after being compressed by an external force and then releasing the external force, the aerogel material can return to its original state, showing excellent rebound performance.

Claims

1. A method for preparing an amino hyperbranched siloxane modified polyimide aerogel material, characterized in that: The steps include: 1) In a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, add 24.37 g of phenyltrimethoxysiloxane, 221.37 g of 3-aminopropyltrimethoxysilane, and 105.32 g of anhydrous methanol, and stir at 0°C for 4 h to mix thoroughly. Slowly add 9.9 g of water dropwise to the reaction system to react at 0°C for 24 h. The solvent is removed by reduced pressure distillation at -0.1 MPa at 40°C for 3 h to obtain HPSi-NH2. 2) In a 1000 mL three-necked flask equipped with a mechanical stirrer and a condenser, 19.02 g of 4,4'-diaminodiphenyl ether, 32.22 g of 3,3',4,4'-benzophenone tetracarboxylic dianhydride, and 461.16 g of N,N-dimethylformamide were added and reacted at -10°C for 12 h. 0.005 mol of HPSi-NH2 was added to the reaction system and reacted at -10°C for 8 h to obtain a phenylsiloxane-modified polyamic acid solution. 3) adding 5.12 g of triethylamine to the phenylsiloxane-modified polyamic acid solution obtained in step 2) in a mass ratio of triethylamine to polyamic acid of 0.1:

1. After the reaction is complete, deionized water is slowly added to the system to fully precipitate the precipitate. The precipitate is filtered and vacuum-dried to obtain a phenyl-functionalized polyamic acid powder. 4) stirring the phenyl-functionalized polyamic acid powder obtained in step 3), 46.112 g of triethylamine, and 102.48 g of deionized water at 0°C for 24 hours to obtain a phenyl-functionalized polyamic acid wet gel, wherein the mass ratio of triethylamine to polyamic acid powder is 0.9:1; freezing the wet gel at -197°C for 1 hour, and then freeze-drying the gel to obtain a phenyl-functionalized polyamic acid xerogel; 5) subjecting the phenyl-functionalized polyamic acid xerogel obtained in step 4) to high-temperature imidization at 150° C. in a nitrogen atmosphere for 12 hours to obtain an amino-hyperbranched siloxane-modified polyimide aerogel material; The HPSi-NH2 has a viscosity of 1500 cps and an amino content of 4.89 mmol / g; The density of the amino hyperbranched siloxane modified polyimide aerogel material is 0.063 g / cm 3 , the porosity is 92%, and the compressive strength at 50% compressive strain is 23kPa.

2. A method for preparing an amino-hyperbranched siloxane-modified polyimide aerogel material, characterized in that: The steps include: 1) In a 1000 mL three-necked flask equipped with a mechanical stirrer and a condenser, add 210.97 g of octyltrimethoxysilane, 21.33 g of p-aminophenyltrimethoxysilane, and 929.2 g of anhydrous ethanol, and stir at 80°C for 1 hour to mix uniformly. Slowly add 27 g of water dropwise to the reaction system to react at 80°C for 1 hour. The solvent is removed by reduced pressure distillation at 80°C and a pressure of -0.05 MPa for 1 hour to obtain HPSi-NH2. 2) In a 250 mL three-necked flask equipped with a mechanical stirrer and a condenser, 12.42 g of 4,4'-diaminodiphenyl sulfone, 21.82 g of pyromellitic dianhydride, and 34.24 g of N,N-dimethylacetamide were added and reacted at 25°C for 2 h. 0.05 mol of HPSi-NH2 was added to the system and reacted at 25°C for 1 h to obtain an octylsiloxane-modified polyamic acid solution. 3) adding 23.97 g of trimethylamine to the octylsiloxane-modified polyamic acid solution obtained in step 2) in a mass ratio of trimethylamine to polyamic acid of 0.7:

1. After the reaction is complete, deionized water is slowly added to the system to fully precipitate. The precipitate is filtered and vacuum-dried to obtain an octyl-functionalized polyamic acid powder. 4) stirring the octyl-functionalized polyamic acid powder obtained in step 3), 10.27 g of trimethylamine, and 616.32 g of deionized water at 80° C. for 2 hours to obtain an octyl-functionalized polyamic acid wet gel, wherein the mass ratio of trimethylamine to polyamic acid powder is 0.3:1; freezing the octyl-functionalized polyamic acid wet gel at −20° C. for 24 hours, and then freeze-drying the octyl-functionalized polyamic acid xerogel. 5) subjecting the octyl-functionalized polyamic acid xerogel obtained in step 4) to high-temperature imidization at 300° C. in an Ar atmosphere for 2 h to obtain an amino-hyperbranched siloxane-modified polyimide aerogel material; The HPSi-NH2 has a viscosity of 3000 cps and an amino content of 0.824 mmol / g; The density of the amino hyperbranched siloxane modified polyimide aerogel material is 0.0521 g / cm 3 , the porosity is 89%.

3. A method for preparing an amino-hyperbranched siloxane-modified polyimide aerogel material, characterized in that: The steps include: 1) In a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, add 99.15 g of phenyltrimethoxysiloxane, 111.18 g of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, and 140.22 g of anhydrous tetrahydrofuran, and stir at room temperature for 2 h to mix uniformly; slowly add 18 g of water dropwise to the reaction system to react at a reaction temperature of 50°C for 12 h; and remove the solvent by vacuum distillation at 50°C and 0 MPa for 2 h to obtain HPSi-NH2; 2) In a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, 8.73 g of 2,6-diaminopyridine, 31.02 g of 3,3',4,4'-diphenylether tetracarboxylic dianhydride, and 119.25 g of N-methylpyrrolidone were added and reacted at 10°C for 8 h. 0.02 mol of HPSi-NH2 was added to the system and reacted at 10°C for 6 h to obtain a phenylsiloxane-modified polyamic acid solution. 3) adding 15.9 g of N,N-dimethylaniline to the phenylsiloxane-modified polyamic acid solution obtained in step 2) in a mass ratio of N,N-dimethylaniline to polyamic acid of 0.4:

1. After the reaction is complete, deionized water is slowly added to the system to fully precipitate, and the precipitate is filtered and vacuum-dried to obtain a phenyl-functionalized polyamic acid powder; 4) The phenyl-functionalized polyamic acid powder obtained in step 3) was stirred at 25° C. for 12 hours with 23.85 g of N,N-dimethylaniline and 145.75 g of deionized water to obtain a phenyl-functionalized polyamic acid wet gel, wherein the mass ratio of N,N-dimethylaniline to polyamic acid powder was 0.6:1; the wet gel was frozen at -10° C. for 18 hours and then freeze-dried to obtain a phenyl-functionalized polyamic acid xerogel; 5) subjecting the phenyl-functionalized polyamic acid xerogel obtained in step 4) to high-temperature imidization at 270° C. in an Ar atmosphere for 8 h to obtain an amino-hyperbranched siloxane-modified polyimide aerogel material; The HPSi-NH2 has a viscosity of 2700 cps and an amino content of 3.68 mmol / g; The density of the amino hyperbranched siloxane modified polyimide aerogel material is 0.0368 g / cm 3 , porosity is 94.2%, and thermal conductivity is 0.0279W / m·K.

4. A method for preparing an amino-hyperbranched siloxane-modified polyimide aerogel material, characterized in that: The steps include: 1) In a 1000 mL three-necked flask equipped with a mechanical stirrer and a condenser, add 120.4 g of 3-chloropropyltriethoxysilane, 22.14 g of 3-aminopropyltriethoxysilane, and 280.72 g of anhydrous acetone, and stir at 40°C for 2 h to mix thoroughly. Then, slowly add 14.04 g of water dropwise to the reaction system to react at 70°C for 8 h. The solvent is removed by vacuum distillation at -0.03 MPa at 50°C for 2 h to obtain HPSi-NH2. 2) In a 500 mL three-necked flask equipped with a mechanical stirrer and a condenser, 24.63 g of bisphenol A diether diamine, 29.42 g of 3,3',4,4'-biphenyltetracarboxylic dianhydride, and 306.28 g of N-ethylpyrrolidone were added and reacted at 10°C for 8 h. 0.04 mol of HPSi-NH2 was added to the system and reacted at 10°C for 6 h to obtain a chlorosiloxane-modified polyamic acid solution. 3) adding 32.43 g of N,N-dimethylbenzylamine to the chlorinated siloxane-modified polyamic acid solution obtained in step 2) in a mass ratio of 0.6:

1. After the reaction is complete, deionized water is slowly added to the system to fully precipitate the precipitate. The precipitate is filtered and vacuum-dried to obtain a chlorinated functionalized polyamic acid powder. 4) The chlorine-functionalized polyamic acid powder obtained in step 3) was stirred at 60° C. for 6 hours with 21.64 g of N,N-dimethylbenzylamine and 486.45 g of deionized water to obtain a chlorine-functionalized polyamic acid wet gel, wherein the mass ratio of N,N-dimethylbenzylamine to polyamic acid powder was 0.4:1; the wet gel was frozen at -10° C. for 18 hours, and then freeze-dried to obtain a chlorine-functionalized polyamic acid xerogel; 5) subjecting the chlorine-functionalized polyamic acid xerogel obtained in step 4) to high-temperature imidization at 270° C. in an Ar atmosphere for 8 h to obtain an amino-hyperbranched siloxane-modified polyimide aerogel material; The HPSi-NH2 has a viscosity of 3500 cps and an amino content of 1.598 mmol / g; The density of the amino hyperbranched siloxane modified polyimide aerogel material is 0.0443 g / cm 3 , porosity is 93.2%, specific surface area is: 12.3m 2 / g.

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