CN111471213A - Amino silicone oil crosslinked polyimide aerogel material and preparation method thereof - Google Patents
Amino silicone oil crosslinked polyimide aerogel material and preparation method thereof Download PDFInfo
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- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
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- C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
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- C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
- C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
- C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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- C08J2483/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen, or carbon only; Derivatives of such polymers
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- C08J2483/08—Polysiloxanes containing silicon bound to organic groups containing atoms other than carbon, hydrogen, and oxygen
Abstract
The invention provides amino silicone oil crosslinked polyimide aerogel and a preparation method thereof. The invention adopts a sol-gel method, namely aromatic acid anhydride and aromatic diamine are used as precursors to prepare polyamic acid, the prepared amino silicone oil cross-linking agent is added to form a cross-linking type polyamic acid structure, wet gel is formed through imidization, and the cross-linking polyimide aerogel with high specific surface area and good mechanical property is obtained through a supercritical carbon dioxide drying technology. Compared with the prior art, the raw materials are cheap and easy to obtain, the reaction process is simple, and the density of the obtained aerogel is less than 0.128g/m3The problem of poor mechanical properties of the conventional aerogel is solved.
Description
Technical Field
The invention belongs to the technical field of aerogels, and particularly relates to an amino silicone oil crosslinked polyimide aerogel material and a preparation method thereof.
Background
Aerogels are a class of lightweight open-cell materials with a multilevel structure using gas as the dispersing medium. The solid phase and the pore structure are both in nanometer level, and the pore diameter is in the mesoporous size. The aerogel has high specific surface area and low density (0.002 g/cm at the lowest) due to extremely high porosity (80-99.9 percent)3) It is the strongest solid material in the world. Meanwhile, the aerogel has a small thermal conductivity coefficient and a low dielectric constant. Therefore, the aerogel is widely applied to the fields of heat insulation, catalytic loading, dust collection, noise adsorption, aerospace, integrated circuits and the like. However, the traditional silica aerogel has poor mechanical properties, the integrity of the corresponding silica aerogel material block is difficult to maintain, and the use temperature is low (lower than 200 ℃), which seriously limits the popularization and application of the aerogel.
Polyimide has attracted much attention as an engineering material having good thermal stability, strong mechanical properties, and excellent aging resistance and heat-insulating properties. Polyimide, as one of the organic aerogels, not only maintains the excellent characteristics of the aerogel, but also improves the corrosion resistance, fatigue resistance, heat resistance, mechanical stability and the like, so the polyimide is an ideal organic aerogel material. The traditional linear polyimide aerogel is prepared by mixing initial monomer dianhydride and diamine in equal proportion to prepare polyimide gel and then preparing the polyimide aerogel through a drying process. However, due to the highly conjugated and large pi plane structure of the main chain of the polyimide molecular chain, the molecular chains are easy to stack, so that the sample has large shrinkage, poor mechanical stability and poor thermal stability. Compared with the prior art, the cross-linked polyimide aerogel limits the accumulation process due to the mutual bonding of the cross-linking agents among molecular chain main chains, and forms a wound three-dimensional network structure, so that the shrinkage of a sample in the aerogel drying process is greatly reduced, and the thermal stability and the mechanical stability of the aerogel are improved. Chinese patent CN107698794A discloses a cross-linked polyimide aerogel prepared by using 4, 4-diaminodiphenyl ether and 3,3',4,4' -biphenyl tetracarboxylic dianhydride as raw materials, 1,3, 5-tris (4-aminophenyl) benzene (TAB) as a cross-linking agent, and by using a supercritical carbon dioxide drying process. The aerogel has less shrinkage and stronger mechanical strength. Chinese patent CN106832364A prepares a flexible cross-linked polyimide aerogel film material by taking octaaminophenyl polyhedral oligomeric silsesquioxane (OAPS) as a cross-linking agent. The film material has lower density and higher tensile strength. Chinese patent CN109535473A uses 1,3,5, 7-tetrakis (4-aminophenyl) adamantane as a cross-linking agent to prepare a cross-linked polyimide aerogel with low water absorption, which can be dried at room temperature under normal pressure or degassed under heating.
Currently used cross-linking agents for polyimide aerogels include 1,3, 5-Triaminophenoxybenzene (TAB), octa (aminophenyl) Silsesquioxane (OAPs), 1,3,5, 7-tetrakis (4-aminophenyl) adamantane, polyhedral oligomeric siloxanes, and 2,4, 6-tris (4-aminophenyl) pyridine (TAP). However, these cross-linking agents are expensive and complex in synthesis process, the raw materials are expensive, and a large amount of toxic organic solvents are used in the preparation process, which is easy to cause serious pollution to the environment. Therefore, the use and popularization of polyimide aerogel is severely limited by the crosslinking agent.
Disclosure of Invention
In view of the above, the present invention aims to provide a polyimide aerogel material crosslinked by amino silicone oil and a preparation method thereof, wherein the aerogel prepared by the method has high mechanical strength.
The invention provides a preparation method of amino silicone oil crosslinked polyimide aerogel material, which comprises the following steps:
dissolving a silane coupling agent with amino in N-methyl pyrrolidone, and then carrying out hydrolytic polymerization to obtain linear polyamino silicone oil with amino on a side group; dissolving diamine and dianhydride in N-methyl pyrrolidone, and stirring to obtain a polyamide acid solution;
and mixing the polyamic acid solution and linear polyamino silicone oil with amino groups on side groups, adding a dehydrating agent, uniformly stirring, aging for 22-26 h after gel is formed, sequentially soaking the obtained aging product in different solvents, and drying by supercritical carbon dioxide to obtain the amino silicone oil crosslinked polyimide aerogel material.
Preferably, the silane coupling agent having an amino group is selected from silane coupling agents having two alkoxy groups and having an amino group.
Preferably, the silane coupling agent having two alkoxy groups with an amino group is selected from one or more of 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminoethylaminopropylmethyldiethoxysilane and divinyltriaminopropylmethyldimethoxysilane.
Preferably, the dianhydride is selected from 3,3',4,4' -biphenyl tetracarboxylic dianhydride; the diamine is selected from 4, 4-diaminodiphenyl ether and/or 4,4 '-diamino-2, 2' -dimethylbiphenyl;
the mass ratio of the diamine to the dianhydride is n: n +1, wherein n is the polymerization degree of the polyimide segment and is 20, 30, 40, 50 or 60.
Preferably, the dehydrating agent is selected from a mixture of acetic anhydride and pyridine;
the mass ratio of the acetic anhydride to the pyridine to the dianhydride is 7.5-8.5: 1.
Preferably, the raw materials are sequentially soaked in N-methyl pyrrolidone, N-methyl pyrrolidone/acetone with the volume ratio of 3:1, N-methyl pyrrolidone/acetone with the volume ratio of 1:3 and acetone for 22-26 h.
Preferably, the drying temperature of the supercritical carbon dioxide is 50-60 ℃, the pressure is 11.5-12.5 MPa, and the time is 46-50 h.
The invention provides an amino silicone oil crosslinked polyimide aerogel material, which is prepared by crosslinking a linear polysiloxane crosslinking agent with amino groups on side groups and polyimide.
The invention provides a preparation method of amino silicone oil crosslinked polyimide aerogel material, which comprises the following steps: dissolving a silane coupling agent with amino in N-methyl pyrrolidone, and then carrying out hydrolytic polymerization to obtain linear polyamino silicone oil with amino on a side group; dissolving diamine and dianhydride in N-methyl pyrrolidone, and stirring to obtain a polyamide acid solution; polymerizing the mixtureAnd mixing an amide acid solution and linear polyamino silicone oil with amino groups on side groups, adding a dehydrating agent, uniformly stirring, aging for 22-26 h after gel formation, sequentially soaking the obtained aging product in different solvents, and drying by supercritical carbon dioxide to obtain the amino silicone oil crosslinked polyimide aerogel material. The method provided by the invention takes low-cost, nontoxic and harmless linear polysiloxane with amino groups on side groups as a cross-linking agent, and adopts a sol-gel method with polyimide and drying under the supercritical carbon dioxide condition to prepare the amino silicone oil cross-linked polyimide aerogel material. The method can retain the excellent mechanical properties and thermal stability of the polyimide aerogel to the maximum extent. The aerogel has low density, high specific surface area and high porosity. The experimental results show that: the specific surface area of the aerogel is 488-546 m2The pore diameter is 20-100 nm, the hydrophobic angle is 50-150 degrees, and the density is 0.036-0.043 g/cm3The thermal conductivity coefficient is 0.031-0.033W/(mK), the modulus is 4.6-24.3 MPa, and the shrinkage rate is 5.2-7.4%.
Drawings
FIG. 1 is an SEM image of an aerogel prepared according to example 1 of the present invention;
FIG. 2 is a photograph of an aerogel prepared in example 2 of the present invention;
FIG. 3 is N of an aerogel prepared in example 3 of the present invention2An adsorption desorption curve;
fig. 4 is a water contact angle graph of an aerogel prepared in example 4 of the present invention.
Detailed Description
The invention provides a preparation method of amino silicone oil crosslinked polyimide aerogel material, which comprises the following steps:
dissolving a silane coupling agent with amino in N-methyl pyrrolidone, and then carrying out hydrolytic polymerization to obtain linear polyamino silicone oil with amino on a side group; dissolving diamine and dianhydride in N-methyl pyrrolidone, and stirring to obtain a polyamide acid solution;
and mixing the polyamic acid solution and linear polyamino silicone oil with amino groups on side groups, adding a dehydrating agent, uniformly stirring, aging for 22-26 h after gel is formed, sequentially soaking the obtained aging product in different solvents, and drying by supercritical carbon dioxide to obtain the amino silicone oil crosslinked polyimide aerogel material.
The method provided by the invention takes low-cost, nontoxic and harmless linear polysiloxane with amino groups on side groups as a cross-linking agent, and adopts a sol-gel method with polyimide and drying under the supercritical carbon dioxide condition to prepare the amino silicone oil cross-linked polyimide aerogel material. The method can retain the excellent mechanical properties and thermal stability of the polyimide aerogel to the maximum extent, improve the elasticity and mechanical strength of the polyimide aerogel under the condition of the same polyimide solid content, and increase the stability of the polyimide aerogel. The aerogel has low density, high specific surface area and high porosity.
The preparation method comprises the steps of dissolving a silane coupling agent with amino groups in N-methylpyrrolidone, then carrying out hydrolytic polymerization to obtain a linear polyamino silicone oil solution with amino groups on side groups, dissolving diamine and dianhydride in N-methylpyrrolidone, and stirring to obtain a polyamic acid solution, wherein the silane coupling agent with amino groups is preferably one or more selected from silane coupling agents with amino groups and containing two alkoxy groups, more preferably from 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminoethylaminopropylmethyldiethoxysilane and divinyltriaminopropylmethyldimethoxysilane.
In the invention, preferably, diamine is dissolved in N-methyl pyrrolidone, stirred, added with dianhydride and stirred again to obtain the polyamic acid solution. In the present invention, the dianhydride is preferably selected from 3,3',4,4' -biphenyltetracarboxylic dianhydride; the diamine is preferably selected from 4, 4-diaminodiphenyl ether and/or 4,4 '-diamino-2, 2' -dimethylbiphenyl; the mass ratio of the diamine to the dianhydride is preferably n: n +1, wherein n is the polymerization degree of the polyimide segment and is 20, 30, 40, 50 or 60.
In specific embodiments of the invention, the molar ratio of diamine to dianhydride is 20:21, 30:31, 40:41, or 50:51, respectively.
The preparation method comprises the steps of mixing the polyamide acid solution with the linear polyamino silicone oil solution with amino groups on the side groups, adding the dehydrating agent, stirring uniformly, aging for 22-26 hours after gel is formed, sequentially soaking the obtained aging product in different solvents, and drying by supercritical carbon dioxide to obtain the amino silicone oil crosslinked polyimide aerogel material.
In a specific embodiment of the invention, the molar ratios of the amino silicone oil, acetic anhydride, pyridine and the dianhydride of the amino silicone oil crosslinked polyimide aerogel material are respectively 2: 176:176:21,2: 256:256:31, 2:336:336:41, or 2:416:416: 51.
In the present invention, the dehydrating agent is selected from a mixture of acetic anhydride and pyridine; the mass ratio of the acetic anhydride, the pyridine and the dianhydride is preferably 7.5-8.5: 1, and more preferably 8:8: 1. The method is preferably carried out for 55-65 s by ultrasonic after adding the dehydrating agent and uniformly stirring to remove bubbles in the solution.
In the invention, the raw materials are preferably soaked in N-methyl pyrrolidone, N-methyl pyrrolidone/acetone with the volume ratio of 3:1, N-methyl pyrrolidone/acetone with the volume ratio of 1:3 and acetone for 22-26 h, and more preferably for 24h in sequence.
In the invention, the drying temperature of the supercritical carbon dioxide is 50-60 ℃, the pressure is 11.5-12.5 MPa, and the time is 46-50 h; in a specific embodiment, the temperature of the supercritical carbon dioxide drying is 55 ℃, the pressure is 12MPa, and the time is 48 h.
The invention provides an amino silicone oil crosslinked polyimide aerogel material, which is prepared by crosslinking a linear polysiloxane crosslinking agent with amino groups on side groups and polyimide.
In particular embodiments of the present invention, the amino silicone oil cross-linked polyimide aerogel material has a hydrophobic angle of 60 °, or 134 °, or 132 °, or 114 °.
To further illustrate the present invention, the following examples are provided to describe the amino silicone oil crosslinked polyimide aerogel material and the preparation method thereof in detail, but they should not be construed as limiting the scope of the present invention.
Example 1
1) Dissolving 3-aminopropylmethyldimethoxysilane (1.633g, 10mmol) in N-methylpyrrolidone (NMP,10m L), slowly adding 342mg of deionized water dropwise, sealing, stirring at room temperature for 24h, and adding N-methylpyrrolidone to 20m L to obtain a linear amino silicone oil solution with amino groups at the side groups (degree of polymerization 20, concentration 0.5 mol/L);
2) dissolving 4, 4-diaminodiphenyl ether (ODA, 0.809g, 4.040mmol) in N-methylpyrrolidone (24m L), stirring for 10min, adding 3,3',4,4' -biphenyl tetracarboxylic dianhydride (BPDA, 1.236g, 4.201mmol), and stirring at room temperature for 30min to form a polyamic acid solution (degree of polymerization 20);
3) adding 0.8m L of amino silicone oil solution with amino groups on the side groups prepared in the step 1) into the polyamic acid solution in the step 2), stirring for 10min, adding 3.35m L of acetic anhydride, adding 3.65m L of pyridine after 1min, continuing stirring for 30s, putting the solution into an ultrasonic reactor, performing ultrasonic treatment for 1min to remove bubbles in the solution, pouring the solution into a mold, gelling at room temperature and aging for 24 h;
4) solvent exchanging the gel obtained in the step 3) in NMP, NMP/acetone (3/1), NMP/acetone (1/1), NMP/acetone (1/3) and acetone solvents for 24 hours respectively;
5) and (3) drying the soaked gel by supercritical carbon dioxide under the drying condition of keeping the pressure of 12MPa at 55 ℃ for 48h to obtain yellow aerogel solid.
6) And (3) putting the aerogel obtained in the step 5) into a vacuum drying oven to be dried in vacuum for 12 hours at the temperature of 60 ℃ so as to remove the carbon dioxide adsorbed in the aerogel.
Fig. 1 is an SEM image of an aerogel prepared in example 1 of the present invention. As can be seen from fig. 1: the obtained polyimide aerogel is of a ribbon fiber structure, and the fiber width is about dozens of nanometers. The aerogel obtained in example 1 had a specific surface area of 546m2The pore diameter distribution is 20-100 nm, the hydrophobic angle is 60 degrees, and the density is 0.036g/cm3The thermal conductivity coefficient is 0.031W/(mK), the modulus is 4.6MPa, and the shrinkage rate is 7.1%.
Example 2:
1) 3-aminopropylmethyldiethoxysilane (1.914g, 10mmol) was dissolved in N-methylpyrrolidone (NMP,10m L), 353mg of deionized water was slowly dropped thereinto and then sealed, and the resulting solution was stirred at room temperature for 24 hours, and N-methylpyrrolidone was further added to the resulting solution to 20m L to prepare a linear amino silicone oil solution having amino groups at the side groups (degree of polymerization 50, concentration 0.5 mol/L)
2) 4,4 '-diamino-2, 2' -dimethylbiphenyl (DMBZ, 0.955g, 4.4.499mmol) was dissolved in N-methylpyrrolidone (25m L), stirred for 10min, then 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA, 1.236g, 4.650mmol) was added, and stirred at room temperature for 30min to form a polyamic acid solution (degree of polymerization 30);
3) adding 0.6m L of amino silicone oil solution with amino groups on the side groups prepared in the step 1) into the polyamic acid solution in the step 2), stirring for 10min, adding 3.65m L of acetic anhydride, adding 3.95m L of pyridine after 1min, continuing stirring for 30s, putting the solution into an ultrasonic reactor, performing ultrasonic treatment for 1min to remove bubbles in the solution, pouring the solution into a mold, gelling at room temperature and aging for 24 h;
4) solvent exchanging the gel obtained in the step 3) in NMP, NMP/acetone (3/1), NMP/acetone (1/1), NMP/acetone (1/3) and acetone solvents for 24 hours respectively;
5) and (3) drying the soaked gel by supercritical carbon dioxide under the drying condition of keeping the pressure of 12MPa at 55 ℃ for 48h to obtain yellow aerogel solid.
6) And (3) putting the aerogel obtained in the step 5) into a vacuum drying oven to be dried in vacuum for 12 hours at the temperature of 60 ℃ so as to remove the carbon dioxide adsorbed in the aerogel.
FIG. 2 is a photograph of an aerogel prepared in example 2 of the present invention;
examples2 the aerogel obtained had a specific surface area of 525m2A density of 0.039g/cm3The pore size distribution is 20-100 nm, the hydrophobic angle is 134 degrees, the thermal conductivity is 0.031W/(mK), the modulus is 32.7MPa, and the shrinkage rate is 5.2%.
Example 3:
1) aminoethylaminopropylmethyldimethoxysilane (2.064g, 10mmol) was dissolved in N-methylpyrrolidone (NMP,10m L), 342mg of deionized water was slowly added dropwise thereto, followed by sealing, stirring at room temperature for 24 hours, and the resulting solution was further added with N-methylpyrrolidone to 20m L to prepare a linear aminosilicone solution having amino groups at the side groups (degree of polymerization 20, concentration 0.5 mol/L)
2) 4,4 '-diamino-2, 2' -dimethylbiphenyl (DMBZ, 1.274g, 6.000mmol) was dissolved in N-methylpyrrolidone (33m L), stirred for 10min, then 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA, 1.809g, 6.148mmol) was added, and stirred at room temperature for 30min to form a polyamic acid solution (degree of polymerization 40);
3) adding 0.6m L of amino silicone oil solution with amino groups on the side groups prepared in the step 1) into the polyamic acid solution in the step 2), stirring for 10min, adding 4.75m L of acetic anhydride, adding 5.20m L of pyridine after 1min, continuing stirring for 30s, putting the solution into an ultrasonic reactor, performing ultrasonic treatment for 1min to remove bubbles in the solution, pouring the solution into a mold, gelling at room temperature and aging for 24 h;
4) solvent exchanging the gel obtained in the step 3) in NMP, NMP/acetone (3/1), NMP/acetone (1/1), NMP/acetone (1/3) and acetone solvents for 24 hours respectively;
5) and (3) drying the soaked gel by supercritical carbon dioxide under the drying condition of keeping the pressure of 12MPa at 55 ℃ for 48h to obtain yellow aerogel solid.
6) And (3) putting the aerogel obtained in the step 5) into a vacuum drying oven to be dried in vacuum for 12 hours at the temperature of 60 ℃ so as to remove the carbon dioxide adsorbed in the aerogel.
The aerogel obtained had a specific surface area of 499m2A density of 0.043g/cm3The pore size distribution is 20-100 nm, the hydrophobic angle is 132 degrees, the thermal conductivity is 0.033W/(mK), the modulus is 22.7MPa, and the shrinkage is 6.9%.
FIG. 3 is N of an aerogel prepared in example 3 of the present invention2An adsorption desorption curve; wherein the abscissa is the relative pressure (p/p)0) The ordinate is the volume adsorption (cm)3STP,/g); it can be seen that the curve belongs to type IV and is an adsorption curve of a typical mesoporous material.
Example 4:
1) 3-aminopropylmethyldimethoxysilane (1.633g, 10mmol) was dissolved in N-methylpyrrolidone (NMP,10m L), 353mg of deionized water was slowly added dropwise thereto, the mixture was sealed, and the mixture was stirred at room temperature for 24 hours, and the resulting solution was further added with N-methylpyrrolidone to 20m L to prepare a solution of linear aminosilicone having amino groups as its side groups (degree of polymerization: 50, concentration: 0.5 mol/L)
2) 4,4 '-diamino-2, 2' -dimethylbiphenyl (DMBZ, 1.062g, 5.003mmol) was dissolved in N-methylpyrrolidone (21m L), stirred for 10min, then 3,3',4,4' -biphenyltetracarboxylic dianhydride (BPDA, 1.501g, 5.102mmol) was added, and stirred at room temperature for 30min to form a polyamic acid solution (degree of polymerization 50);
3) adding 0.4m L of amino silicone oil solution with amino groups on the side groups prepared in the step 1) into the polyamic acid solution in the step 2), stirring for 10min, adding 3.95m L of acetic anhydride, adding 4.30m L of pyridine after 1min, continuing stirring for 30s, putting the solution into an ultrasonic reactor, performing ultrasonic treatment for 1min to remove bubbles in the solution, pouring the solution into a mold, gelling at room temperature and aging for 24 h;
4) solvent exchanging the gel obtained in the step 3) in NMP, NMP/acetone (3/1), NMP/acetone (1/1), NMP/acetone (1/3) and acetone solvents for 24 hours respectively;
5) and (3) drying the soaked gel by supercritical carbon dioxide under the drying condition of keeping the pressure of 12MPa at 55 ℃ for 48h to obtain yellow aerogel solid.
6) And (3) putting the aerogel obtained in the step 5) into a vacuum drying oven to be dried in vacuum for 12 hours at the temperature of 60 ℃ so as to remove the carbon dioxide adsorbed in the aerogel.
Example 4 the aerogel obtained has a specific surface area of 488m2A density of 0.038g/cm3The pore size distribution is 20-100 nm, the hydrophobic angle is 114 degrees, the thermal conductivity is 0.033W/(mK), the modulus is 24.3MPa, and the shrinkage rate is 7.4%.
Fig. 4 is a water contact angle graph of an aerogel prepared in example 4 of the present invention, and it can be seen from fig. 4 that the hydrophobic angle of the aerogel is 114 °.
From the above embodiments, the present invention provides a method for preparing a polyimide aerogel material crosslinked by amino silicone oil, comprising the following steps: dissolving a silane coupling agent with amino in N-methyl pyrrolidone, and then carrying out hydrolytic polymerization to obtain linear polyamino silicone oil with amino on a side group; dissolving diamine and dianhydride in N-methyl pyrrolidone, and stirring to obtain a polyamide acid solution; and mixing the polyamic acid solution and linear polyamino silicone oil with amino groups on side groups, adding a dehydrating agent, uniformly stirring, aging for 22-26 h after gel is formed, sequentially soaking the obtained aging product in different solvents, and drying by supercritical carbon dioxide to obtain the amino silicone oil crosslinked polyimide aerogel material. The method provided by the invention takes low-cost, nontoxic and harmless linear polysiloxane with amino groups on side groups as a cross-linking agent, and adopts a sol-gel method with polyimide and drying under the supercritical carbon dioxide condition to prepare the amino silicone oil cross-linked polyimide aerogel material. The method can retain the excellent mechanical properties and thermal stability of the polyimide aerogel to the maximum extent, improve the elasticity and mechanical strength of the polyimide aerogel under the condition of the same polyimide solid content, and increase the stability of the polyimide aerogel. The aerogel has low density, high specific surface area and high porosity. The experimental results show that: the specific surface area of the aerogel is 488-546 m2The density is 0.036-0.043 g/cm3The hydrophobic angle is 50-150 degrees, the pore diameter is distributed at 20-100 nm, the heat conductivity coefficient is 0.031-0.033W/(mK), the modulus is 4.6-24.3 MPa, and the shrinkage rate is 5.2-7.4%.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.
Claims (8)
1. A preparation method of amino silicone oil crosslinked polyimide aerogel material comprises the following steps:
dissolving a silane coupling agent with amino in N-methyl pyrrolidone, and then carrying out hydrolytic polymerization to obtain a linear polyamino silicone oil solution with amino on a side group; dissolving diamine and dianhydride in N-methyl pyrrolidone, and stirring to obtain a polyamide acid solution;
and mixing the polyamide acid solution with a linear polyamino silicone oil solution with amino groups on side groups, adding a dehydrating agent, uniformly stirring, aging for 22-26 hours after gel is formed, sequentially soaking the obtained aging product in different solvents, and drying by supercritical carbon dioxide to obtain the amino silicone oil crosslinked polyimide aerogel material.
2. The production method according to claim 1, wherein the silane coupling agent having an amino group is selected from silane coupling agents having an amino group and containing two alkoxy groups.
3. The method according to claim 2, wherein the silane coupling agent having two alkoxy groups and having an amino group is one or more selected from the group consisting of 3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, aminoethylaminopropylmethyldimethoxysilane, aminoethylaminopropylmethyldiethoxysilane and divinyltriaminopropylmethyldimethoxysilane.
4. The method according to claim 1, wherein the dianhydride is selected from 3,3',4,4' -biphenyltetracarboxylic dianhydride; the diamine is selected from 4, 4-diaminodiphenyl ether and/or 4,4 '-diamino-2, 2' -dimethylbiphenyl;
the mass ratio of the diamine to the dianhydride is n: n +1, wherein n is the polymerization degree of the polyimide segment and is 20, 30, 40, 50 or 60.
5. The process according to claim 1, wherein the dehydrating agent is selected from a mixture of acetic anhydride and pyridine;
the mass ratio of the acetic anhydride to the pyridine to the dianhydride is 7.5-8.5: 1.
6. The preparation method according to claim 1, wherein the N-methylpyrrolidone, the N-methylpyrrolidone/acetone in a volume ratio of 3:1, the N-methylpyrrolidone/acetone in a volume ratio of 1:3, and the acetone are sequentially soaked for 22-26 hours.
7. The preparation method according to claim 1, wherein the supercritical carbon dioxide drying temperature is 50-60 ℃, the pressure is 11.5-12.5 MPa, and the time is 46-50 h.
8. The amino silicone oil crosslinked polyimide aerogel material is characterized by being prepared by crosslinking a linear polysiloxane crosslinking agent with amino groups on side groups and polyimide.
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| CN105384950A (en) * | 2015-12-14 | 2016-03-09 | 同济大学 | Low-cost preparation method of low-density crosslinking type polyimide aerogel material |
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