Disclosure of Invention
The invention aims to provide a multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, and a preparation method and application thereof.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, which comprises the following steps:
mixing the carbon nano tube dispersion liquid, the dianhydride monomer and the diamine monomer, carrying out polymerization reaction, mixing the obtained polymerization reaction liquid with 3-aminopropyltriethoxysilane, and carrying out polycondensation reaction to obtain a precursor of the carbon nano tube grafted polyimide;
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out heat treatment to obtain the multi-crosslinked carbon nano tube grafted polyimide heat-conducting film;
the dianhydride monomer is aromatic tetracarboxylic dianhydride; the diamine monomer is aromatic diamine or a mixture of aromatic diamine and hydroxylated aromatic diamine.
Preferably, the carbon nanotubes in the carbon nanotube dispersion are hydroxylated carbon nanotubes.
Preferably, the ratio of the mass of the carbon nanotubes in the carbon nanotube dispersion to the total mass of the dianhydride monomer, the diamine monomer and the 3-aminopropyltriethoxysilane is (5-10): (90-95).
Preferably, the dianhydride monomer, the diamine monomer and the 3-aminopropyltriethoxysilane are present in a mass ratio of 1: (0.94-0.98): (0.04 to 0.12);
the molar ratio of the aromatic diamine to the hydroxylated aromatic diamine is (0.8-1): (0-0.2).
Preferably, the temperature of the polymerization reaction is room temperature, and the time of the polymerization reaction is 2-4 h;
the temperature of the polycondensation reaction is room temperature, and the time of the polycondensation reaction is 8-12 h.
Preferably, the heat treatment process is as follows: and sequentially preserving the obtained wet film at 40 ℃ for 4-8 h, heating to 60 ℃ for 4-8 h, heating to 80 ℃ for 1-3 h, heating to 100 ℃ for 1-3 h, heating to 120 ℃ for 2-4 h, heating to 200 ℃ for 1-2 h, heating to 250 ℃ for 1-2 h, and heating to 300 ℃ for 0.5-1 h.
Preferably, the carbon nanotube dispersion liquid includes carbon nanotubes and an organic solvent;
the mass ratio of the carbon nano tube to the organic solvent is (5-10): (900-1900).
Preferably, the aromatic tetracarboxylic dianhydride is pyromellitic dianhydride, 3,4',4' -biphenyltetracarboxylic dianhydride, 3,4',4' -benzophenonetetracarboxylic dianhydride or 4,4' -oxydiphthalic anhydride;
the aromatic diamine is 4,4 '-diaminodiphenyl ether, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 4' -bis (4-aminophenoxy) benzophenone or 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane;
the hydroxylated aromatic diamine is 3,3' -dihydroxybenzidine, 3' -dihydroxy-4, 4' -diaminodiphenylmethane, 3, 5-bis (4-aminophenoxy) phenol or 4- (bis (4-aminophenyl) amino) phenol.
The invention also provides a multi-crosslinked carbon nanotube grafted polyimide heat-conducting film prepared by the preparation method in the technical scheme, which comprises the carbon nanotube, 3-aminopropyltriethoxysilane and polyimide.
The invention also provides the application of the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film in the technical scheme in the fields of flexible printed circuit substrates, microelectronic integrated circuits, battery packages or special electrical appliances.
The invention provides a preparation method of a multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, which comprises the following steps: mixing the carbon nano tube dispersion liquid, the dianhydride monomer and the diamine monomer, carrying out polymerization reaction, mixing the obtained polymerization reaction liquid with 3-aminopropyltriethoxysilane, and carrying out polycondensation reaction to obtain a precursor of the carbon nano tube grafted polyimide; after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out heat treatment to obtain the multi-crosslinked carbon nano tube grafted polyimide heat-conducting film; the dianhydride monomer is aromatic tetracarboxylic dianhydride; the diamine monomer is aromatic diamine or a mixture of aromatic diamine and hydroxylated aromatic diamine. The preparation method provided by the invention comprises the steps of mixing a carbon nano tube dispersion liquid, a dianhydride monomer and a diamine monomer for a polymerization reaction, then adding 3-aminopropyltriethoxysilane, after adding, performing self-polycondensation between the 3-aminopropyltriethoxysilane, hydrolyzing ethoxy groups on the 3-aminopropyltriethoxysilane into hydroxyl groups, then performing polycondensation with the hydroxyl groups on polyimide respectively, and performing polycondensation with the hydroxyl groups on the surface of the carbon nano tube to form three different crosslinking sites, thereby obtaining the carbon nano tube grafted polyimide heat conducting film with a multi-crosslinking structure; the preparation method increases the interaction between the polymeric chains, increases the compatibility between the carbon nano tube and the polyimide, reduces the interface thermal resistance, and further improves the heat-conducting property of the polyimide film. According to the records of the embodiments, the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film prepared by the preparation method has excellent heat conductivity coefficient and mechanical properties, wherein the heat conductivity coefficient is 0.36-0.73W/mK, the tensile strength is 124-129 MPa, the tensile modulus is 2.41-2.59 GPa, and the elongation at break is 36.1-36.6%. Meanwhile, the preparation method provided by the invention is an in-situ polymerization reaction, is simple and is easy for industrial production.
Detailed Description
The invention provides a preparation method of a multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, which comprises the following steps:
mixing the carbon nano tube dispersion liquid, the dianhydride monomer and the diamine monomer, carrying out polymerization reaction, mixing the obtained polymerization reaction liquid with 3-aminopropyltriethoxysilane, and carrying out polycondensation reaction to obtain a precursor of the carbon nano tube grafted polyimide;
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out heat treatment to obtain the multi-crosslinked carbon nano tube grafted polyimide heat-conducting film;
the dianhydride monomer is aromatic tetracarboxylic dianhydride; the diamine monomer is aromatic diamine or a mixture of aromatic diamine and hydroxylated aromatic diamine.
In the present invention, all the raw material components are commercially available products well known to those skilled in the art unless otherwise specified.
According to the invention, carbon nanotube dispersion liquid, dianhydride monomer and diamine monomer are mixed, and after polymerization reaction, the obtained polymerization reaction liquid is mixed with 3-aminopropyltriethoxysilane to carry out polycondensation reaction, so as to obtain a precursor of carbon nanotube grafted polyimide.
In the present invention, the carbon nanotube dispersion preferably includes carbon nanotubes and an organic solvent; the carbon nanotube is preferably a hydroxylated carbon nanotube; the hydroxylated carbon nanotube is preferably one or more of a hydroxylated single-wall carbon nanotube, a hydroxylated double-wall carbon nanotube and a hydroxylated multi-wall carbon nanotube. In the invention, the length of the carbon nanotube is preferably 2-30 μm, more preferably 5-20 μm, and the length-diameter ratio of the carbon nanotube is preferably (250-1000): 1, more preferably (500-1000): 1. The organic solvent is preferably one or more of N, N-dimethylformamide, N-dimethylacetamide and N-methylpyrrolidone; when the organic solvent is more than two of the above specific choices, the invention has no special limitation on the proportion of each specific substance, and can mix the specific substances according to any proportion. In the invention, the mass ratio of the carbon nanotubes to the organic solvent is preferably (5-10): (900-1900), more preferably (6-9): (1000 to 1800), most preferably (7 to 8): (1200-1600).
In the invention, the mass content of hydroxyl in the hydroxylated carbon nanotube is preferably 2.92-3.96%.
In the present invention, the method for preparing the carbon nanotube dispersion preferably includes: and mixing the carbon nano tube with an organic solvent to obtain a carbon nano tube dispersion liquid. The temperature of the mixing is preferably room temperature; the mixing is preferably carried out under the condition of ultrasonic treatment, and the ultrasonic treatment time is preferably 3 hours; the power of the ultrasound is not limited in any way in the present invention, and can be performed with a power well known to those skilled in the art.
In the invention, the dianhydride monomer is aromatic tetracarboxylic dianhydride; the aromatic tetracarboxylic dianhydride is preferably pyromellitic dianhydride, 3,4',4' -biphenyltetracarboxylic dianhydride, 3,4',4' -benzophenonetetracarboxylic dianhydride or 4,4' -oxydiphthalic anhydride. In the present invention, the diamine monomer is an aromatic diamine; or the diamine monomer is a mixture of an aromatic diamine and a hydroxylated aromatic diamine. In the present invention, the aromatic diamine is preferably 4,4 '-diaminodiphenyl ether, 2-bis [4- (4-aminophenoxy) phenyl ] propane, 4' -bis (4-aminophenoxy) benzophenone, or 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane; the hydroxylated aromatic diamine is 3,3' -dihydroxybenzidine, 3' -dihydroxy-4, 4' -diaminodiphenylmethane, 3, 5-bis (4-aminophenoxy) phenol or 4- (bis (4-aminophenyl) amino) phenol. In the present invention, when the diamine monomer is an aromatic diamine and a hydroxylated aromatic diamine, the molar ratio of the aromatic diamine to the hydroxylated aromatic diamine is preferably (0.8 to 1): (0 to 0.2), more preferably (0.85 to 0.95): (0.05-0.15).
In the present invention, the ratio of the mass of the carbon nanotubes in the carbon nanotube dispersion to the total mass of the dianhydride monomer, the diamine monomer, and the 3-aminopropyltriethoxysilane is preferably (5 to 10): (90-95), more preferably (6-9): (91-94), most preferably (7-8): 92-93). In the present invention, the ratio of the amounts of the dianhydride monomer, diamine monomer, and 3-aminopropyltriethoxysilane is preferably 1: (0.94-0.98): (0.04 to 0.12), more preferably 1: (0.95-0.96): (0.06-0.1).
The mixing order of the carbon nanotube dispersion, the dianhydride monomer and the diamine monomer is not particularly limited, and the carbon nanotube dispersion, the dianhydride monomer and the diamine monomer may be mixed by a mixing order known to those skilled in the art.
In the invention, the temperature of the polymerization reaction is preferably room temperature, and the time of the polymerization reaction is preferably 2-4 h, and more preferably 2.5-3.5 h.
The method for adding the 3-aminopropyltriethoxysilane is not limited in any way, and the 3-aminopropyltriethoxysilane can be added by a method known to one skilled in the art.
In the invention, the temperature of the polycondensation reaction is preferably room temperature, and the time of the polycondensation reaction is preferably 8-12 h, and more preferably 9-10 h.
After a precursor of the carbon nano tube grafted polyimide is obtained, the precursor of the carbon nano tube grafted polyimide is subjected to film preparation and heat treatment to obtain the multi-crosslinked carbon nano tube grafted polyimide heat-conducting film.
The film-forming process is not particularly limited, and the film-forming process may be performed by a process known to those skilled in the art.
In the present invention, the heat treatment process is preferably: sequentially preserving heat of the obtained wet film at 40 ℃ for 4-8 h, heating to 60 ℃ for 4-8 h, heating to 80 ℃ for 1-3 h, heating to 100 ℃ for 1-3 h, heating to 120 ℃ for 2-4 h, heating to 200 ℃ for 1-2 h, heating to 250 ℃ for 1-2 h, and heating to 300 ℃ for 0.5-1 h; more preferably: and sequentially preserving the heat of the obtained wet film at 40 ℃ for 5-6 h, heating to 60 ℃ for 6-7 h, heating to 80 ℃ for 2h, heating to 100 ℃ for 2h, heating to 120 ℃ for 3h, heating to 200 ℃ for 1.5h, heating to 250 ℃ for 1.5h, and heating to 300 ℃ for 0.8 h.
After the heat treatment is finished, the invention preferably further comprises the steps of sequentially cooling, soaking, washing and drying the film obtained after the heat treatment. The temperature reduction is not limited in any way, and can be carried out by adopting a process well known to those skilled in the art. In the present invention, the soaking is preferably performed in deionized water, and the soaking time and the amount of deionized water used in the present invention are not limited in any way, and those amounts of deionized water and soaking time known to those skilled in the art can be used. In the invention, the detergent used for washing is preferably ethanol or acetone; the washing process of the present invention is not particularly limited, and may be carried out by a process known to those skilled in the art. The drying is not particularly limited in the present invention and may be carried out by a process known to those skilled in the art.
The invention also provides a multi-crosslinked carbon nanotube grafted polyimide heat-conducting film prepared by the preparation method in the technical scheme, which comprises the carbon nanotube, 3-aminopropyltriethoxysilane and polyimide. In the invention, the mass ratio of the carbon nanotube, the 3-aminopropyltriethoxysilane and the polyimide is preferably (5.26-11.11): (1.06-6.53): (93.87-98.85), more preferably 11.11:6.53: 93.87.
In the invention, three different crosslinking sites are formed among the 3-aminopropyltriethoxysilane, between the 3-aminopropyltriethoxysilane and the polyimide after the ethoxy group on the 3-aminopropyltriethoxysilane is hydrolyzed into the hydroxyl group, and between the 3-aminopropyltriethoxysilane and the polyimide after the ethoxy group on the 3-aminopropyltriethoxysilane is hydrolyzed into the hydroxyl group.
The invention also provides the application of the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film in the technical scheme in the fields of flexible printed circuit substrates, microelectronic integrated circuits, battery packages or special electrical appliances. The method of the present invention is not particularly limited, and the method may be performed by a method known to those skilled in the art.
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
0.2227g of hydroxylated multi-wall carbon nanotube (the length is 2 mu m, the length-diameter ratio is 250: 1, and the mass content of hydroxyl in the hydroxylated multi-wall carbon nanotube is 3.06%) and 40.09g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 3h, 2.1812g (0.01mol) of pyromellitic dianhydride and 1.9624g (0.0098mol) of 4,4 '-diaminodiphenyl ether are sequentially added for carrying out polymerization reaction for 2h, and 0.0884g (0.0004mol) of 3-aminopropyltriethoxysilane is added for carrying out polycondensation reaction (room temperature, 8h) to obtain a precursor of the carbon nanotube grafted polyimide, which is marked as 1';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 4h, heating to 60 ℃ for 4h, heating to 80 ℃ for 1h, heating to 100 ℃ for 1h, heating to 120 ℃ for 2h, heating to 200 ℃ for 1h, heating to 250 ℃ for 1h, heating to 300 ℃ for 0.5h, cooling to room temperature, soaking in deionized water, washing with ethanol, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 1.
Example 2
0.4702g of hydroxylated multi-wall carbon nanotube (the length is 2 mu m, the length-diameter ratio is 250: 1, and the mass content of hydroxyl in the hydroxylated multi-wall carbon nanotube is 3.06%) and 43.32g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 3h, 2.1812g (0.01mol) of pyromellitic dianhydride and 1.9624g (0.0098mol) of 4,4 '-diaminodiphenyl ether are sequentially added for carrying out polymerization reaction for 2h, and 0.0884g (0.0004mol) of 3-aminopropyltriethoxysilane is added for carrying out polycondensation reaction (room temperature, 12h) to obtain a precursor of the carbon nanotube grafted polyimide, which is marked as 2';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 4h, heating to 60 ℃ for 4h, heating to 80 ℃ for 1h, heating to 100 ℃ for 1h, heating to 120 ℃ for 2h, heating to 200 ℃ for 1h, heating to 250 ℃ for 1h, heating to 300 ℃ for 0.5h, cooling to room temperature, soaking in deionized water, washing with ethanol, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 2.
Example 3
0.3715g of hydroxylated double-wall carbon nanotube (the length is 5 μm, the length-diameter ratio is 500: 1, the mass content of hydroxyl in the hydroxylated double-wall carbon nanotube is 2.92%) and 141.18g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 6h, 2.9422g (0.01mol) of 3,3,4',4' -biphenyltetracarboxylic dianhydride and 3.9401g (0.0096mol) of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane are sequentially added to carry out polymerization reaction for 4h, 0.1768g (0.0008mol) of 3-aminopropyltriethoxysilane is added to carry out polycondensation reaction (room temperature, 8h), and a precursor of carbon nanotube grafted polyimide is obtained and is marked as 3 ';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 8h, heating to 60 ℃ for 8h, heating to 80 ℃ for 3h, heating to 100 ℃ for 3h, heating to 120 ℃ for 4h, heating to 200 ℃ for 2h, heating to 250 ℃ for 2h, heating to 300 ℃ for 1h, cooling to room temperature, soaking in deionized water, washing with ethanol, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 3.
Example 4
0.7843g of hydroxylated double-wall carbon nanotube (the length is 5 μm, the length-diameter ratio is 500: 1, and the mass content of hydroxyl in the hydroxylated double-wall carbon nanotube is 2.92%) and 70.59g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 6h, 2.9422g (0.01mol) of 3,3,4',4' -biphenyltetracarboxylic dianhydride and 3.9401g (0.0096mol) of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane are sequentially added to carry out polymerization reaction for 4h, 0.1768g (0.0008mol) of 3-aminopropyltriethoxysilane is added to carry out polycondensation reaction (room temperature, 12h), and a precursor of carbon nanotube grafted polyimide is obtained and is marked as 4 ';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 8h, heating to 60 ℃ for 8h, heating to 80 ℃ for 3h, heating to 100 ℃ for 3h, heating to 120 ℃ for 4h, heating to 200 ℃ for 2h, heating to 250 ℃ for 2h, heating to 300 ℃ for 1h, cooling to room temperature, soaking in deionized water, washing with acetone, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 4.
Example 5
0.3797g of hydroxylated single-wall carbon nanotube (the length is 5 mu m, the length-diameter ratio is 1000:1, the mass content of hydroxyl in the hydroxylated single-wall carbon nanotube is 3.96%) and 144.28g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 5 hours, 3.2223g (0.01mol) of 3,3,4',4' -benzophenone tetracarboxylic dianhydride and 3.7266g (0.0094mol) of 4,4 '-bis (4-aminophenoxy) benzophenone are sequentially added to carry out polymerization reaction for 3 hours, and 0.2652g (0.0012mol) of 3-aminopropyltriethoxysilane is added to carry out polycondensation reaction (room temperature for 10 hours) to obtain a precursor of carbon nanotube grafted polyimide, which is marked as 5';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 6h, heating to 60 ℃ for 6h, heating to 80 ℃ for 2h, heating to 100 ℃ for 2h, heating to 120 ℃ for 3h, heating to 200 ℃ for 2h, heating to 250 ℃ for 2h, heating to 300 ℃ for 1h, cooling to room temperature, soaking in deionized water, washing with acetone, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 5.
Example 6
0.8016g of hydroxylated single-wall carbon nanotube (the length is 5 mu m, the length-diameter ratio is 1000:1, the mass content of hydroxyl in the hydroxylated single-wall carbon nanotube is 3.96%) and 152.30g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 5 hours, 3.2223g (0.01mol) of 3,3,4',4' -benzophenone tetracarboxylic dianhydride and 3.7266g (0.0094mol) of 4,4 '-bis (4-aminophenoxy) benzophenone are sequentially added to carry out polymerization reaction for 3 hours, and 0.2652g (0.0012mol) of 3-aminopropyltriethoxysilane is added to carry out polycondensation reaction (room temperature for 12 hours) to obtain a precursor of carbon nanotube grafted polyimide, which is marked as 6';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (3) sequentially preserving heat at 40 ℃ for 6h, heating to 60 ℃ for 6h, heating to 80 ℃ for 2h, heating to 100 ℃ for 2h, heating to 120 ℃ for 3h, heating to 200 ℃ for 2h, heating to 250 ℃ for 2h, heating to 300 ℃ for 1h, cooling to room temperature, soaking in deionized water, washing with acetone, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 6.
Example 7
0.4353g of hydroxylated multi-wall carbon nanotube (length: 15 μm, length-diameter ratio: 500: 1, mass content of hydroxyl in the hydroxylated multi-wall carbon nanotube: 3.06%) and 78.36g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 3h, 3.1022g (0.01mol) of 4,4' -oxydiphthalic anhydride and 3.7266g (0.0098mol) of 4,4' -bis (4-aminophenoxy) benzophenone are sequentially added to carry out polymerization reaction for 3h, 0.0884g (0.0004mol) of 3-aminopropyltriethoxysilane is added to carry out polycondensation reaction (room temperature, 8h), and a precursor of carbon nanotube grafted polyimide is obtained, which is recorded as 7 ';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 4h, heating to 60 ℃ for 4h, heating to 80 ℃ for 1h, heating to 100 ℃ for 1h, heating to 120 ℃ for 2h, heating to 200 ℃ for 1h, heating to 250 ℃ for 1h, heating to 300 ℃ for 0.5h, cooling to room temperature, soaking in deionized water, washing with acetone, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 7.
Example 8
0.9191g of hydroxylated multi-walled carbon nanotube (length: 30 μm, length-diameter ratio: 1000:1, mass content of hydroxyl in the hydroxylated multi-walled carbon nanotube: 3.06%) and 82.71g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 3h, 3.1022g (0.01mol) of 4,4 '-oxydiphthalic anhydride and 5.0809g (0.0098mol) of 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane are sequentially added for polymerization reaction for 2h, 0.0884g (0.0004mol) of 3-aminopropyltriethoxysilane is added for polycondensation reaction (room temperature, 12h), and a precursor of carbon nanotube grafted polyimide, namely 8', is obtained;
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 4h, heating to 60 ℃ for 4h, heating to 80 ℃ for 1h, heating to 100 ℃ for 1h, heating to 120 ℃ for 2h, heating to 200 ℃ for 1h, heating to 250 ℃ for 1h, heating to 300 ℃ for 0.5h, cooling to room temperature, soaking in deionized water, washing with ethanol, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 8.
Example 9
0.4737g of hydroxylated multi-wall carbon nanotube (the length is 15 μm, the length-diameter ratio is 500: 1, and the mass content of hydroxyl in the hydroxylated multi-wall carbon nanotube is 3.06%) and 42.63g of N, N-dimethylformamide are mixed at room temperature, after ultrasonic treatment is carried out for 3h, 2.1812g (0.01mol) of pyromellitic dianhydride, 1.5699g (0.00784mol) of 4,4' -diaminodiphenyl ether and 0.4238g (0.00196mol) of 3,3' -dihydroxybenzidine are sequentially added to carry out polymerization reaction for 2h, 0.0884g (0.0004mol) of 3-aminopropyltriethoxysilane is added to carry out polycondensation reaction (room temperature, 10h), and a precursor of carbon nanotube grafted polyimide, namely 9', is obtained;
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (3) sequentially preserving heat at 40 ℃ for 4h, heating to 60 ℃ for 4h, heating to 80 ℃ for 1h, heating to 100 ℃ for 1h, heating to 120 ℃ for 2h, heating to 200 ℃ for 1h, heating to 250 ℃ for 1h, heating to 300 ℃ for 0.5h, cooling to room temperature, soaking in deionized water, washing with ethanol, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 9.
Example 10
0.7459g of hydroxylated double-wall carbon nanotube (length: 5 μm, length-diameter ratio: 500: 1, mass content of hydroxyl in the hydroxylated double-wall carbon nanotube: 2.92%) and 141.72g of N, N-dimethylformamide are mixed at room temperature, after 6 hours of ultrasonic treatment, 2.9422g (0.01mol) of 3,3,4',4' -biphenyltetracarboxylic dianhydride, 3.1521g (0.00768mol) of 2, 2-bis [4- (4-aminophenoxy) phenyl ] propane and 0.4421g (0.00192mol) of 3,3' -dihydroxy-4, 4' -diaminodiphenylmethane are sequentially added to carry out polymerization reaction for 4 hours, 0.1768g (0.0008mol) of 3-aminopropyltriethoxysilane is added to carry out polycondensation reaction (room temperature, 8 hours) to obtain a precursor of carbon nanotube-grafted polyimide, which is marked as 10 ';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 8h, heating to 60 ℃ for 8h, heating to 80 ℃ for 3h, heating to 100 ℃ for 3h, heating to 120 ℃ for 4h, heating to 200 ℃ for 2h, heating to 250 ℃ for 2h, heating to 300 ℃ for 1h, cooling to room temperature, soaking in deionized water, washing with acetone, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 10.
Example 11
0.7831g of hydroxylated double-wall carbon nanotube (length: 5 μm, length-diameter ratio: 500: 1, mass content of hydroxyl in the hydroxylated double-wall carbon nanotube: 2.92%) and 156.63g of N-methylpyrrolidone are mixed at room temperature, after 5 hours of ultrasonic treatment, 3.2223g (0.01mol) of 3,3,4',4' -benzophenone tetracarboxylic dianhydride, 2.9813g (0.00752mol) of 4,4 '-bis (4-aminophenoxy) benzophenone and 0.5797g (0.00188mol) of 3, 5-bis (4-aminophenoxy) phenol are sequentially added to perform polymerization reaction for 3 hours, 0.2652g (0.0012mol) of 3-aminopropyltriethoxysilane is added to perform polycondensation reaction (room temperature, 12 hours), and a precursor of the carbon nanotube-grafted polyimide is obtained, which is recorded as 11';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 6h, heating to 60 ℃ for 6h, heating to 80 ℃ for 2h, heating to 100 ℃ for 2h, heating to 120 ℃ for 3h, heating to 200 ℃ for 2h, heating to 250 ℃ for 2h, heating to 300 ℃ for 1h, cooling to room temperature, soaking in deionized water, washing with ethanol, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 11.
Example 12
0.8696g of hydroxylated multi-walled carbon nanotube (length: 15 μm, length-diameter ratio: 500: 1, mass content of hydroxyl in the hydroxylated multi-walled carbon nanotube: 3.06%) and 78.27g of N, N-dimethylformamide are mixed at room temperature, after 3 hours of ultrasonic treatment, 3.1022g (0.01mol) of 4,4 '-oxydiphthalic anhydride, 4.0647g (0.00784mol) of 2, 2-bis [4- (4-aminophenoxy) phenyl ] hexafluoropropane and 0.5710g (0.00196mol) of 4- (bis (4-aminophenyl) amino) phenol are sequentially added for polymerization reaction for 2 hours, 0.0884g (0.0004mol) of 3-aminopropyltriethoxysilane is added for reaction, and polycondensation reaction is carried out (room temperature, 10 hours) to obtain a precursor of carbon nanotube grafted polyimide, which is marked as 12';
after the precursor of the carbon nano tube grafted polyimide is prepared into a film, carrying out temperature programming treatment: and (2) sequentially preserving heat at 40 ℃ for 4h, heating to 60 ℃ for 4h, heating to 80 ℃ for 1h, heating to 100 ℃ for 1h, heating to 120 ℃ for 2h, heating to 200 ℃ for 1h, heating to 250 ℃ for 1h, heating to 300 ℃ for 0.5h, cooling to room temperature, soaking in deionized water, washing with ethanol, and drying to obtain the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film, wherein the mark is 12.
Test example
The heat conductivity of the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film and the pure kapton polyimide film prepared in the examples 1 to 12 was tested, and the test process was as follows: the heat transfer test was performed using a TC3000 heat transfer instrument at 25 ℃ based on astm d 5930. The thermal conductivity was calculated by the following formula:
wherein K is the thermal conductivity coefficient, W/mK; q is the heat generated by the unit length of the wire; Δ T is the temperature change of the wire; t is the test time. The test results are shown in table 1:
TABLE 1 thermal conductivity coefficients of the multi-crosslinked carbon nanotube-grafted polyimide thermal conductive films and the pure kapton polyimide films prepared in examples 1 to 12
And (3) carrying out mechanical property test on the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film and the pure PI film prepared in the embodiment 1-2, wherein the test process comprises the following steps: the tensile test was performed by a Shimadzu AG-I Universal tensile tester at room temperature, based on the ASTM D882-88 standard. The test results are shown in table 2:
TABLE 2 mechanical properties of the multi-crosslinked carbon nanotube-grafted polyimide thermal conductive film and the pure PI film prepared in examples 1 to 2
The infrared spectrum test of the multi-crosslinked carbon nanotube grafted polyimide heat-conducting film and the pure PI film prepared in the examples 1-2 is performed, and the test results are shown in FIG. 1 (a is the pure PI film, b is the example 1, and c is the example 2), and it can be seen from FIG. 1 that all the samples have 1776cm-1And 1714cm-1Asymmetric and symmetric vibration peak at C ═ O, 1366cm-1The characteristic peak is derived from polyimide.b and c are at 2921cm-1And 2846cm-1Occurrence of-CH2The symmetric and asymmetric stretching vibration peaks prove that the APTES and the PI successfully react. And no-NH of APTES2and-OH absorption peak of carbon nanotubes, indicating successful grafting of polyimide chains onto carbon nanotubes.
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.