CN113136032A - Space atomic oxygen-resistant optically transparent thermosetting shape memory polyimide, and preparation method and application thereof - Google Patents

Space atomic oxygen-resistant optically transparent thermosetting shape memory polyimide, and preparation method and application thereof Download PDF

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CN113136032A
CN113136032A CN202110454005.1A CN202110454005A CN113136032A CN 113136032 A CN113136032 A CN 113136032A CN 202110454005 A CN202110454005 A CN 202110454005A CN 113136032 A CN113136032 A CN 113136032A
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shape memory
thermal imidization
imidization reaction
memory polyimide
acid solution
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CN113136032B (en
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杨增辉
张耀明
陶立明
张新瑞
王齐华
王廷梅
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Lanzhou Institute of Chemical Physics LICP of CAS
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    • C08G73/06—Polycondensates having nitrogen-containing heterocyclic rings in the main chain of the macromolecule
    • C08G73/10—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
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Abstract

The invention provides a space atomic oxygen resistant optically transparent thermosetting shape memory polyimide, a preparation method and application thereof, relating to the technical field of high-performance functional materials. The preparation method comprises the steps of synthesizing an anhydride-terminated polyamide acid solution by an in-situ polycondensation method, then mixing a phosphorus-containing triamine cross-linking agent with the anhydride-terminated polyamide acid solution, cross-linking polyamide acid, coating the cross-linked polyamide acid on a substrate, removing a solvent, and further performing thermal imidization reaction to obtain the thermosetting shape memory polyimide with space atom oxygen resistance and optical transparency. The thermosetting shape memory polyimide prepared by the invention has excellent shape memory performance and optical transparency, and can form a passivation layer under atomic oxygen irradiation to protect internal materials from being further corroded by atomic oxygen.

Description

Space atomic oxygen-resistant optically transparent thermosetting shape memory polyimide, and preparation method and application thereof
Technical Field
The invention relates to the technical field of high-performance functional materials, in particular to a space atomic oxygen resistant and optically transparent thermosetting shape memory polyimide, and a preparation method and application thereof.
Background
Shape memory polyimide, as a high-performance shape memory polymer with high glass transition temperature, high mechanical strength and excellent thermal stability, can play an important role as a functional device in the aspects of space-expandable structures, high-temperature actuators, deformable optical devices and the like. Especially, the optically transparent shape memory polyimide is expected to be used as a flexible transparent substrate to replace ITO glass, and is widely applied to space flexible wearable and flexible display equipment.
Chinese patents CN104004188A, CN105542205B and CN108456309A disclose high temperature shape memory polyimides with thermal, electrical and processing properties, and although the reported polyimide materials obtain high glass transition temperature and excellent shape memory property, they all have a certain degree of color and cannot meet the application requirements of optical devices.
Chinese patent CN109825079A discloses a light-colored transparent high-temperature-resistant shape memory polyimide film material and a preparation method thereof; chinese patent CN108587164A discloses a shape memory polyimide with adjustable color and a preparation method thereof. However, none of the reported optically transparent polyimides are resistant to steric oxygen and are susceptible to performance degradation or failure by attack by atomic oxygen in the low earth orbit; the polyimide is thermoplastic polyimide, and the performances such as creep resistance and the like are weaker than those of thermosetting polyimide.
Therefore, the improvement of atomic oxygen resistance, creep resistance and other capabilities of the shape memory polyimide while maintaining optical transparency is of great significance for meeting the application requirements and high reliability of space optical devices, and no space atomic oxygen resistance and optical transparency resistant shape memory polyimide material is reported at present.
Disclosure of Invention
The thermosetting shape memory polyimide prepared by the invention has excellent shape memory performance and optical transparency, can form a passivation layer under the irradiation of atomic oxygen and protects internal materials from being further corroded by the atomic oxygen.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of thermosetting shape memory polyimide with resistance to space atomic oxygen and optical transparency, which comprises the following steps:
mixing hydrophobic silicon dioxide nano particles with an organic solvent to obtain a silicon dioxide dispersion liquid;
mixing the silicon dioxide dispersion liquid and a diamine monomer to obtain a diamine solution;
mixing the diamine solution and the dianhydride monomer, and carrying out polycondensation reaction to obtain an anhydride-terminated polyamide acid solution;
mixing the anhydride-terminated polyamide acid solution and a phosphorus-containing triamine crosslinking agent, and carrying out crosslinking reaction to obtain a crosslinked polyamide acid solution;
and coating the cross-linked polyamic acid solution on a substrate, heating to remove the organic solvent, and performing thermal imidization reaction to obtain the thermosetting shape memory polyimide.
Preferably, the particle size of the hydrophobic silica nanoparticles is 10-100 nm.
Preferably, the diamine monomer is one or more of 4,4 '-diamino-2, 2' -bistrifluoromethylbiphenyl, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 2 '-bis [4- (4-aminophenoxyphenyl) ] propane and 4,4' -diaminodiphenyl ether;
the dianhydride monomer is 4,4' - (4,4' -isopropyl diphenoxy) bis (phthalic anhydride) and/or 4,4' - (hexafluoroisopropylidene) diphthalic anhydride.
Preferably, the molar ratio of the diamine monomer to the dianhydride monomer is 0.9:1 to 0.99: 1.
Preferably, the polycondensation reaction is carried out at room temperature, and the time of the polycondensation reaction is 8-24 h.
Preferably, the phosphorus-containing triamine crosslinker comprises tris (4-aminophenyl) thiophosphate.
Preferably, the amount of the substance of the phosphorus-containing triamine crosslinking agent is 0.33 to 3.5 percent of the total amount of the diamine monomer and the dianhydride monomer.
Preferably, the thermal imidization reaction includes a first thermal imidization reaction, a second thermal imidization reaction, a third thermal imidization reaction, and a fourth thermal imidization reaction, which are sequentially performed;
the temperature of the first thermal imidization reaction is 100-140 ℃, and the time is 0.5-2 h;
the temperature of the second thermal imidization reaction is 150-180 ℃, and the time is 0.5-2 h;
the temperature of the third thermal imidization reaction is 180-220 ℃, and the time is 0.5-2 h;
the temperature of the fourth thermal imidization reaction is 240-280 ℃ and the time is 0.5-2 h.
The invention also provides the thermosetting shape memory polyimide prepared by the preparation method in the technical scheme.
The invention also provides application of the thermosetting shape memory polyimide in the technical scheme in patterning display equipment, optical films, organic photovoltaic solar panels, flexible printed circuit boards, touch panels, low-earth-orbit functional electronic and deformable electrical appliance components in a space complex environment.
The invention provides a preparation method of thermosetting shape memory polyimide with resistance to space atomic oxygen and optical transparency, which comprises the following steps: mixing hydrophobic silicon dioxide nano particles with an organic solvent to obtain a silicon dioxide dispersion liquid; mixing the silicon dioxide dispersion liquid and a diamine monomer to obtain a diamine solution; mixing the diamine solution and the dianhydride monomer, and carrying out polycondensation reaction to obtain an anhydride-terminated polyamide acid solution; mixing the anhydride-terminated polyamide acid solution and a phosphorus-containing triamine crosslinking agent, and carrying out crosslinking reaction to obtain a crosslinked polyamide acid solution; and coating the cross-linked polyamic acid solution on a substrate, heating to remove the organic solvent, and performing thermal imidization reaction to obtain the thermosetting shape memory polyimide. The preparation method comprises the steps of synthesizing an anhydride-terminated polyamide acid solution by an in-situ polycondensation method, then mixing a phosphorus-containing triamine cross-linking agent with the anhydride-terminated polyamide acid solution, cross-linking polyamide acid, coating the cross-linked polyamide acid on a substrate, removing a solvent, and further performing thermal imidization reaction to obtain the thermosetting shape memory polyimide with space atom oxygen resistance and optical transparency.
In the invention, the hydrophobic silicon dioxide nano particles have good dispersibility, and can ensure that the thermosetting shape memory polyimide has transparency; the thermosetting shape memory polyimide prepared by the invention contains silicon dioxide and phosphorus elements, can form a passivation layer during atomic oxygen irradiation, and has the function of resisting space atomic oxygen irradiation. The example results show that the thermosetting shape memory polyimide prepared by the invention has adjustable glass transition temperature of 225-250 ℃, adjustable tensile strength of 80-100 MPa and excellent shape memory performance (R)f≥98％，RrMore than or equal to 95 percent); the thermosetting shape memory polyimide prepared by the invention has high optical transparency (the light transmittance with the wavelength of 550nm is more than 88%); the thermosetting shape memory polyimide prepared by the invention can form a strong passivation layer under the irradiation of atomic oxygen, so that the internal material is protected from further erosion of the atomic oxygen, and the thermosetting shape memory polyimide still has high shape memory performance after the irradiation of the atomic oxygen.
Drawings
FIG. 1 is a graph of the thermo-mechanical properties of a thermoset shape memory polyimide prepared in example 1;
FIG. 2 is a graph of shape memory performance of a thermoset shape memory polyimide prepared in example 1, cycled three times;
FIG. 3 is a graph showing the effect of optical transparency of the thermosetting shape memory polyimide prepared in example 1;
FIG. 4 is a comparative electron microscope image of shape memory polyimides prepared in example 1 and comparative example 1 after atomic oxygen irradiation.
Detailed Description
The invention provides a preparation method of thermosetting shape memory polyimide with resistance to space atomic oxygen and optical transparency, which comprises the following steps:
mixing hydrophobic silicon dioxide nano particles with an organic solvent to obtain a silicon dioxide dispersion liquid;
mixing the silicon dioxide dispersion liquid and a diamine monomer to obtain a diamine solution;
mixing the diamine solution and the dianhydride monomer, and carrying out polycondensation reaction to obtain an anhydride-terminated polyamide acid solution;
mixing the anhydride-terminated polyamide acid solution and a phosphorus-containing triamine crosslinking agent, and carrying out crosslinking reaction to obtain a crosslinked polyamide acid solution;
and coating the cross-linked polyamic acid solution on a substrate, heating to remove the organic solvent, and performing thermal imidization reaction to obtain the thermosetting shape memory polyimide.
In the present invention, unless otherwise specified, the starting materials for the preparation are all commercially available products well known to those skilled in the art.
According to the invention, hydrophobic silicon dioxide nano particles and an organic solvent are mixed to obtain a silicon dioxide dispersion liquid. In a specific embodiment of the invention, the hydrophobic silica nanoparticles are commercially available Wacker hydrophobic fumed silica. In the invention, the particle size of the hydrophobic silicon dioxide nano-particles is preferably 10-100 nm, and more preferably 15-50 nm. In the present invention, the organic solvent preferably includes N-methylpyrrolidone, N-dimethylformamide or N, N-dimethylacetamide. In the invention, the mixing preferably comprises stirring and ultrasonic treatment which are carried out in sequence, and the stirring time is preferably 30 min; the power of the ultrasonic treatment is preferably 500W, and the time of the ultrasonic treatment is preferably 30 min. In the invention, the hydrophobic silica nanoparticles have good dispersibility in an organic solvent, and can improve the space atom oxygen resistance of the thermosetting shape memory polyimide, and simultaneously, the transparency of the polyimide is not influenced, and the polyimide still has good transparency.
In the present invention, the mass content of the hydrophobic silica nanoparticles in the silica dispersion is preferably 0.5 to 5%, and more preferably 1%. In the present invention, the silica dispersion is transparent.
After the silicon dioxide dispersion liquid is obtained, the silicon dioxide dispersion liquid and the diamine monomer are mixed to obtain the diamine solution. In the present invention, the diamine monomer is preferably one or more of 4,4' -diamino-2, 2' -bistrifluoromethylbiphenyl, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 2' -bis [4- (4-aminophenoxyphenyl) ] propane and 4,4' -diaminodiphenyl ether, and particularly preferably 4,4' -diamino-2, 2' -bistrifluoromethylbiphenyl and 2,2' -bis [4- (4-aminophenoxyphenyl) ] propane. In the present invention, when the diamine monomer is two different diamine monomers, the molar ratio of the two different diamine monomers is preferably 1 to 2: 1. In a specific embodiment of the present invention, when the diamine monomer is 4,4 '-diamino-2, 2' -bistrifluoromethylbiphenyl and 2,2 '-bis [4- (4-aminophenoxyphenyl) ] propane, the molar ratio of the 4,4' -diamino-2, 2 '-bistrifluoromethylbiphenyl and 2,2' -bis [4- (4-aminophenoxyphenyl) ] propane is 1-2: 1.
In the invention, the mass ratio of the diamine monomer to the hydrophobic silica nanoparticles is preferably 1-15%, and more preferably 1.3-13%.
In the present invention, the method of mixing the silica dispersion and the diamine monomer is preferably: a diamine monomer is added to the silica dispersion and mixed. In the present invention, the temperature of the mixing is preferably room temperature, and the mixing is preferably performed under a protective atmosphere, more preferably under a nitrogen atmosphere, and particularly preferably under a dry nitrogen atmosphere; the mixing is preferably carried out under stirring conditions, and the invention has no special requirements on the specific parameters of the stirring, and is suitable for completely dissolving the diamine monomer.
After obtaining the diamine solution, the diamine solution and the dianhydride monomer are mixed for polycondensation reaction to obtain the anhydride terminated polyamide acid solution. In the present invention, the dianhydride monomer is preferably 4,4' - (4,4' -isopropyldiphenoxy) bis (phthalic anhydride) and/or 4,4' - (hexafluoroisopropylidene) diphthalic anhydride. In the present invention, when the dianhydride monomer is a combination of 4,4'- (4,4' -isopropyldiphenoxy) bis (phthalic anhydride) and 4,4'- (hexafluoroisopropylpropylene) diphthalic anhydride, the molar ratio of 4,4' - (4,4 '-isopropyldiphenoxy) bis (phthalic anhydride) to 4,4' - (hexafluoroisopropylpropylene) diphthalic anhydride is preferably 1:2 to 2:1, and more preferably 1: 1.
In the present invention, the molar ratio of the diamine monomer to the dianhydride monomer is preferably 0.90 to 0.99:1, and more preferably 0.92 to 0.96: 1.
In the present invention, the method of mixing the diamine solution and the dianhydride monomer is preferably: the dianhydride was added to the diamine solution in portions.
In the invention, the polycondensation reaction is preferably carried out under the ice-water bath condition, and the time of the polycondensation reaction is preferably 8-24 h, and more preferably 12 h. In the present invention, the polycondensation reaction is preferably carried out under a protective atmosphere, more preferably under a nitrogen atmosphere. In the present invention, the polycondensation reaction is preferably carried out under stirring conditions.
After the anhydride-terminated polyamic acid solution is obtained, the anhydride-terminated polyamic acid solution and the phosphorus-containing triamine crosslinking agent are mixed for crosslinking reaction to obtain the crosslinked polyamic acid solution. In the present invention, the phosphorus-containing triamine crosslinking agent preferably includes tris (4-aminophenyl) thiophosphate. In the present invention, the amount of the phosphorus-containing triamine crosslinking agent is preferably 0.33 to 3.5%, more preferably 1.36 to 2.78% of the total amount of the diamine monomer and the dianhydride monomer.
In the present invention, the method of mixing the anhydride-terminated polyamic acid solution and the phosphorus-containing triamine crosslinking agent is preferably: a phosphorus-containing triamine crosslinker is added to the anhydride-terminated polyamic acid solution.
In the present invention, the crosslinking reaction is preferably performed under ice-water bath conditions; the crosslinking reaction is preferably carried out under protective atmosphere conditions, more preferably under a nitrogen atmosphere. In the present invention, the crosslinking reaction is preferably under stirring conditions; the time of the crosslinking reaction is preferably 8-24 h, and more preferably 12 h.
After the cross-linked polyamic acid solution is obtained, the cross-linked polyamic acid solution is coated on a substrate, the organic solvent is removed by heating, and then the thermosetting shape memory polyimide is obtained by thermal imidization. In the present invention, the substrate is preferably a glass substrate, and the substrate is preferably a clean, flat substrate. The thickness of the coating is not required to be special, and the thickness of the coating is determined according to the thickness required by the thermosetting shape memory polyimide. In the embodiment of the invention, the thickness of the coating is preferably 20-120 μm. In the invention, the heating temperature is preferably 50-100 ℃, and more preferably 80 ℃; the heating time is preferably 3-8 h, and more preferably 5 h. In the present invention, the heating is preferably performed under vacuum conditions.
In the present invention, the thermal imidization reaction preferably includes a first thermal imidization reaction, a second thermal imidization reaction, a third thermal imidization reaction, and a fourth thermal imidization reaction, which are performed in this order; the temperature of the first thermal imidization reaction is preferably 100-140 ℃, more preferably 120 ℃, and the time is preferably 0.5-2 h, more preferably 1 h; the temperature of the second thermal imidization reaction is preferably 150-180 ℃, more preferably 150 ℃, and the time is preferably 0.5-2 h, more preferably 1 h; the temperature of the third thermal imidization reaction is preferably 180-220 ℃, more preferably 200 ℃, and the time is preferably 0.5-2 h, more preferably 1 h; the temperature of the fourth thermal imidization reaction is preferably 240-280 ℃, more preferably 250 ℃, and the time is preferably 0.5-2 hours, more preferably 1 hour. The invention adopts the step-by-step thermal imidization reaction to fully carry out the imidization reaction.
In the present invention, a temperature increase rate from room temperature to the temperature of the first thermal imidization reaction, a temperature increase rate from the temperature of the first thermal imidization reaction to the temperature of the second thermal imidization reaction, a temperature increase rate from the temperature of the second thermal imidization reaction to the temperature of the third thermal imidization reaction, and a temperature increase rate from the temperature of the third thermal imidization reaction to the temperature of the fourth thermal imidization reaction are independently preferably 3 to 10 ℃/min, and more preferably 5 ℃/min.
In the present invention, after the thermal imidization, the substrate is preferably removed to obtain a thermosetting shape memory polyimide. In the present invention, the method of removing a substrate preferably includes: and cooling the system obtained by the thermal imidization reaction to room temperature, and then placing the system in hot water to strip the thermosetting shape memory polyimide from the substrate. In the present invention, the temperature of the hot water is preferably 95 ℃.
In the present invention, it is preferable that the thermosetting shape-memory polyimide obtained by peeling is washed and dried in this order to obtain an optically transparent thermosetting shape-memory polyimide which is resistant to steric oxygen. In the invention, the cleaning agent used for cleaning is preferably distilled water; the drying temperature is preferably 50-100 ℃, and more preferably 80 ℃.
The invention also provides the thermosetting shape memory polyimide prepared by the preparation method in the technical scheme. In the present invention, the thickness of the thermosetting shape memory polyimide is preferably 40 to 120 μm, and more preferably 60 to 80 μm. The thermosetting shape memory polyimide provided by the invention is a polyimide material which is reinforced by silicon dioxide and is crosslinked by a phosphorus-containing crosslinking agent.
In the invention, the glass transition temperature of the thermosetting shape memory polyimide is above 220 ℃, preferably adjustable at 225-250 ℃, and the tensile strength is 80-100 MPa; the light transmittance of the thermosetting shape memory polyimide is more than 88 percent; shape fixation ratio (R) of the thermosetting shape memory polyimidef) Not less than 98%, shape recovery ratio (R)r) More than or equal to 95 percent; the thermosetting shape memory polyimide provided by the invention can form a passivation layer under atomic oxygen irradiation, protects internal materials from being further corroded by atomic oxygen, and has the performance of resisting the corrosion of space atomic oxygen.
The invention also provides application of the thermosetting shape memory polyimide in the technical scheme in patterning display equipment, optical films, organic photovoltaic solar panels, flexible printed circuit boards and touch panels in space complex environments. The thermosetting shape memory polyimide provided by the invention has the characteristics of space atomic oxygen corrosion resistance and optical transparency, still has high shape memory performance after atomic oxygen irradiation, and can meet the application requirements of optical devices for space. In addition, the glass transition temperature of the thermosetting shape memory polyimide prepared by the invention is above 220 ℃, and the thermosetting shape memory polyimide can be applied to electronic and deformable electric appliance components with low earth orbit functions.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Adding 0.0457g of hydrophobic silica nanoparticles with the particle size of 50nm into 30mL of N-methylpyrrolidone, stirring for 30min, and carrying out ultrasonic treatment for 30min under the power of 500W to obtain a transparent silica dispersion liquid;
adding 2.35mmol of 4,4' -diamino-2, 2' -bistrifluoromethylbiphenyl and 2.35mmol of 2,2' -bis [4- (4-aminophenoxyphenyl) ] propane into the transparent silicon dioxide dispersion, and stirring at room temperature under a dry nitrogen atmosphere until the mixture is dissolved to obtain a diamine solution;
adding 5mmol of 4,4'- (4,4' -isopropyldiphenoxy) bis (phthalic anhydride) into the diamine solution, stirring for 12 hours under the conditions of nitrogen atmosphere and ice water bath, and carrying out polycondensation reaction to obtain an anhydride-terminated polyamic acid solution;
adding 0.2mmol of tris (4-aminophenyl) thiophosphate cross-linking agent into the anhydride-terminated polyamic acid solution, and continuously stirring for 12 hours under the conditions of nitrogen atmosphere and ice-water bath to obtain a cross-linked polyamic acid solution;
uniformly coating the cross-linked polyamic acid solution on a horizontal glass substrate, and heating in a vacuum oven at 80 ℃ to volatilize the solvent for 5 hours; and then gradually heating to 120 ℃ at the heating rate of 5 ℃/min, preserving heat for 1h at 150 ℃, preserving heat for 1h at 200 ℃, preserving heat for 1h at 250 ℃, cooling to room temperature of 25 ℃, peeling the thermosetting shape memory polyimide from the glass substrate in hot water at 95 ℃, washing the obtained peeled object with distilled water, and drying at 80 ℃ to obtain the space atomic oxygen-resistant optically transparent thermosetting shape memory polyimide.
The thickness of the thermosetting shape memory polyimide prepared in this example was 80 μm.
Example 2
Adding 0.0457g of hydrophobic silica nanoparticles with the particle size of 50nm into 30mL of N, N-dimethylformamide, stirring for 30min, and carrying out ultrasonic treatment for 30min under the power of 500W to obtain a transparent silica dispersion liquid;
adding 3.2mmol of 4,4' -diamino-2, 2' -bistrifluoromethylbiphenyl and 1.6mmol of 2,2' -bis [4- (4-aminophenoxyphenyl) ] propane into the transparent silicon dioxide dispersion, and stirring at room temperature under a dry nitrogen atmosphere until the mixture is dissolved to obtain a diamine solution;
adding 5mmol of 4,4' - (hexafluoroisopropylidene) diphthalic anhydride into the diamine solution, stirring for 12 hours under the conditions of nitrogen atmosphere and ice-water bath, and carrying out polycondensation reaction to obtain anhydride-terminated polyamic acid solution;
adding 0.133mmol of tris (4-aminophenyl) thiophosphate cross-linking agent into the anhydride-terminated polyamic acid solution, and continuously stirring for 12 hours under the conditions of nitrogen atmosphere and ice-water bath to obtain a cross-linked polyamic acid solution;
uniformly coating the cross-linked polyamic acid solution on a horizontal glass substrate, and heating in a vacuum oven at 80 ℃ to volatilize the solvent for 5 hours; and then gradually heating to 120 ℃ at the heating rate of 5 ℃/min, preserving heat for 1h at 150 ℃, preserving heat for 1h at 200 ℃, preserving heat for 1h at 250 ℃, cooling to room temperature of 25 ℃, peeling the thermosetting shape memory polyimide from the glass substrate in hot water at 95 ℃, washing the obtained peeled object with distilled water, and drying at 80 ℃ to obtain the space atomic oxygen-resistant optically transparent thermosetting shape memory polyimide.
The thickness of the thermosetting shape memory polyimide prepared in this example was 60 μm.
Example 3
0.1370g of hydrophobic silica nanoparticles with the particle size of 15nm are added into 30mL of N, N-dimethylformamide, stirred for 30min and ultrasonically treated for 30min under the power of 500W to obtain transparent silica dispersion liquid;
adding 4.8mmol of 4,4 '-diamino-2, 2' -bistrifluoromethylbiphenyl into the transparent silicon dioxide dispersion liquid, and stirring the mixture at room temperature under a dry nitrogen atmosphere until the mixture is dissolved to obtain a diamine solution;
adding 2.5mmol of 4,4' - (4,4' -isopropyldiphenoxy) bis (phthalic anhydride) and 2.5mmol of 4,4' - (hexafluoroisopropylidene) diphthalic anhydride into the diamine solution, stirring for 12 hours under the conditions of nitrogen atmosphere and ice-water bath, and carrying out polycondensation reaction to obtain an anhydride-terminated polyamic acid solution;
adding 0.133mmol of tris (4-aminophenyl) thiophosphate cross-linking agent into the anhydride-terminated polyamic acid solution, and continuously stirring for 12 hours under the conditions of nitrogen atmosphere and ice-water bath to obtain a cross-linked polyamic acid solution;
uniformly coating the cross-linked polyamic acid solution on a horizontal glass substrate, and heating in a vacuum oven at 80 ℃ to volatilize the solvent for 5 hours; and then gradually heating to 120 ℃ at the heating rate of 5 ℃/min, preserving heat for 1h at 150 ℃, preserving heat for 1h at 200 ℃, preserving heat for 1h at 250 ℃, cooling to room temperature of 25 ℃, peeling the thermosetting shape memory polyimide from the glass substrate in hot water at 95 ℃, washing the obtained peeled object with distilled water, and drying at 80 ℃ to obtain the space atomic oxygen-resistant optically transparent thermosetting shape memory polyimide.
The thickness of the thermosetting shape memory polyimide prepared in this example was 60 μm.
Example 4
0.1370g of hydrophobic silica nanoparticles with the particle size of 50nm are added into 30mL of N, N-dimethylformamide, stirred for 30min and ultrasonically treated for 30min under the power of 500W to obtain transparent silica dispersion liquid;
adding 2.3mmol of 4,4' -diamino-2, 2' -bistrifluoromethylbiphenyl and 2.3mmol of 2,2' -bis [4- (4-aminophenoxyphenyl) ] propane into the transparent silicon dioxide dispersion, and stirring at room temperature under a dry nitrogen atmosphere until the mixture is dissolved to obtain a diamine solution;
adding 5mmol of 4,4' - (hexafluoroisopropylidene) diphthalic anhydride into the diamine solution, stirring for 12 hours under the conditions of nitrogen atmosphere and ice-water bath, and carrying out polycondensation reaction to obtain anhydride-terminated polyamic acid solution;
adding 0.267mmol of tris (4-aminophenyl) thiophosphate cross-linking agent into the anhydride-terminated polyamic acid solution, and continuously stirring for 12 hours under the conditions of nitrogen atmosphere and ice-water bath to obtain a cross-linked polyamic acid solution;
uniformly coating the cross-linked polyamic acid solution on a horizontal glass substrate, and heating in a vacuum oven at 80 ℃ to volatilize the solvent for 5 hours; and then gradually heating to 120 ℃ at the heating rate of 5 ℃/min, preserving heat for 1h at 150 ℃, preserving heat for 1h at 200 ℃, preserving heat for 1h at 250 ℃, cooling to room temperature of 25 ℃, peeling the thermosetting shape memory polyimide from the glass substrate in hot water at 95 ℃, washing the obtained peeled object with distilled water, and drying at 80 ℃ to obtain the space atomic oxygen-resistant optically transparent thermosetting shape memory polyimide.
The thickness of the thermosetting shape memory polyimide prepared in this example was 80 μm.
Comparative example 1
Adding 2.5mmol of 4,4' -diamino-2, 2' -bistrifluoromethylbiphenyl and 2.5mmol of 2,2' -bis [4- (4-aminophenoxyphenyl) ] propane into 30 mLN-methyl pyrrolidone, and stirring at room temperature under a dry nitrogen atmosphere until the mixture is dissolved to obtain a diamine solution; then adding 5mmol of 4,4'- (4,4' -isopropyl diphenoxy) bis (phthalic anhydride), stirring for 22h under the conditions of nitrogen atmosphere and ice water bath, and carrying out polycondensation reaction to obtain an anhydride-terminated polyamic acid solution;
uniformly coating the anhydride-terminated polyamic acid solution on a horizontal glass substrate, heating in a vacuum oven at 80 ℃ to volatilize the solvent for 5 hours, then gradually heating to 120 ℃ at the heating rate of 5 ℃/min, keeping the temperature for 1 hour at 150 ℃, keeping the temperature for 1 hour at 200 ℃, keeping the temperature for 1 hour at 250 ℃, cooling to room temperature of 25 ℃, peeling the polyimide from the glass in hot water at 95 ℃, washing the obtained peeled object with distilled water, and drying at 80 ℃ to obtain the transparent shape memory polyimide.
Test example 1
FIG. 1 is a graph of the thermo-mechanical properties of a thermoset shape memory polyimide prepared in example 1. As can be seen from the dissipation factor curve in FIG. 1, the glass transition temperature of the thermosetting shape memory polyimide prepared by the present invention can reach 231 deg.C (the peak of the dissipation factor curve represents the glass transition temperature). As can be seen from the storage modulus curve, the thermosetting shape memory polyimide prepared by the invention has high modulus (storage modulus 3.1GPa at 30 ℃), a good rubbery platform (storage modulus 10.0MPa at 251 ℃) above the glass transition temperature, and the change of the storage modulus curve which is obvious near the glass transition temperature shows that the polyimide has good shape memory performance.
Test example 2
FIG. 2 is a graph showing the shape memory characteristics of the thermosetting shape memory polyimide prepared in example 1, which was cycled three times, and from which it was calculated that the shape fixation rate was 98% and the shape recovery rate was 95%.
Test example 3
Fig. 3 is a diagram showing an effect of optical transparency of the thermosetting shape memory polyimide prepared in example 1, in which characters on paper can be clearly seen through the thermosetting shape memory polyimide when the thermosetting shape memory polyimide prepared in example 1 is coated on the paper printed with the characters, and as can be seen from fig. 3, the thermosetting shape memory polyimide prepared in the present invention has good optical transparency, good light transmittance and no color.
Test example 4
FIG. 4 is a comparative electron microscope image of shape memory polyimides prepared in example 1 and comparative example 1 after atomic oxygen irradiation. According to the invention, as the silicon dioxide and the phosphorus-containing triamide crosslinking agent are introduced, a blanket-like structure is formed on the surface, and the structure is characterized in that a passivation layer is formed on the surface by phosphorus oxide formed by irradiation of the silicon dioxide and the phosphorus-containing triamide crosslinking agent, so that further erosion of a bottom layer material is effectively prevented. While comparative example 1, which does not contain silica and phosphorus, shows more severe erosion after the action of atomic oxygen, and has a large amount of resin residue on the surface.
According to the detection results of the examples and the comparative examples, the thermosetting shape memory polyimide prepared by the invention has excellent shape memory performance and optical transparency, and can form a passivation layer under atomic oxygen irradiation to protect internal materials from being further corroded by atomic oxygen.
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 (10)

1. A method for preparing thermosetting shape memory polyimide with the advantages of space atom oxygen resistance and optical transparency comprises the following steps:
mixing hydrophobic silicon dioxide nano particles with an organic solvent to obtain a silicon dioxide dispersion liquid;
mixing the silicon dioxide dispersion liquid and a diamine monomer to obtain a diamine solution;
mixing the diamine solution and the dianhydride monomer, and carrying out polycondensation reaction to obtain an anhydride-terminated polyamide acid solution;
mixing the anhydride-terminated polyamide acid solution and a phosphorus-containing triamine crosslinking agent, and carrying out crosslinking reaction to obtain a crosslinked polyamide acid solution;
and coating the cross-linked polyamic acid solution on a substrate, heating to remove the organic solvent, and performing thermal imidization reaction to obtain the thermosetting shape memory polyimide.
2. The method according to claim 1, wherein the hydrophobic silica nanoparticles have a particle size of 10 to 100 nm.
3. The method according to claim 1, wherein the diamine monomer is one or more selected from the group consisting of 4,4 '-diamino-2, 2' -bistrifluoromethylbiphenyl, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane, 2 '-bis [4- (4-aminophenoxy phenyl) ] propane and 4,4' -diaminodiphenyl ether;
the dianhydride monomer is 4,4' - (4,4' -isopropyl diphenoxy) bis (phthalic anhydride) and/or 4,4' - (hexafluoroisopropylidene) diphthalic anhydride.
4. The method according to claim 1 or 3, wherein the molar ratio of the diamine monomer to the dianhydride monomer is 0.9:1 to 0.99: 1.
5. The preparation method according to claim 1, wherein the polycondensation reaction is carried out at room temperature, and the polycondensation reaction time is 8-24 hours.
6. The method of claim 1, wherein the phosphorus-containing triamine crosslinker comprises tris (4-aminophenyl) thiophosphate.
7. The method according to claim 1 or 6, wherein the amount of the substance of the phosphorus-containing triamine crosslinking agent is 0.33 to 3.5% of the total amount of the diamine monomer and the dianhydride monomer.
8. The method according to claim 1, wherein the thermal imidization reaction includes a first thermal imidization reaction, a second thermal imidization reaction, a third thermal imidization reaction, and a fourth thermal imidization reaction, which are performed in this order;
the temperature of the first thermal imidization reaction is 100-140 ℃, and the time is 0.5-2 h;
the temperature of the second thermal imidization reaction is 150-180 ℃, and the time is 0.5-2 h;
the temperature of the third thermal imidization reaction is 180-220 ℃, and the time is 0.5-2 h;
the temperature of the fourth thermal imidization reaction is 240-280 ℃ and the time is 0.5-2 h.
9. A thermosetting shape memory polyimide produced by the production method according to any one of claims 1 to 8.
10. Use of the thermoset shape memory polyimide of claim 9 in patterned display devices, optical films, organic photovoltaic solar panels, flexible printed circuit boards, touch panels, and low-earth-orbit functional electronic, flexible electrical components in spatially complex environments.
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CN115873246A (en) * 2022-11-30 2023-03-31 中国科学院兰州化学物理研究所 High-temperature-resistant thermosetting supramolecular shape memory polyimide and preparation method thereof
CN116178714A (en) * 2023-02-28 2023-05-30 武汉理工大学 Fluorine-containing modified polyimide and preparation method and application thereof
CN115873246B (en) * 2022-11-30 2024-06-07 中国科学院兰州化学物理研究所 High-temperature-resistant high-solidity supermolecule shape memory polyimide and preparation method thereof

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