CN100336849C - Preparation method of polyimide siloxanel polyimide two face different property composite film - Google Patents

Abstract

The present invention belongs to the field of high molecular materials, and particularly relates to a novel perparation method for polyimide siloxane/polyimide double-face isomerism complex films. The method comprises: preparing polyamic acid siloxane prepolymer; preparing polyamic acid prepolymer; preparing the polyimide siloxane / polyimide double-face isomerism complex films. The present invention utilizes synthetic polyamic acid siloxane and polyamic acid as raw materials, and utilizes tetrahydrofuran, N, N-dimethyl formamide, N, N-dimethyl acetamide or N-methyl pyrrolidone as a component solvent. PDMS chain segment parts move to the upper surfaces of the films in the process of volatilizing the solvent when low-boiling THF volatilizes under low temperature. The complex films prepared by the present invention use block copolymer and pure PI making films, have good compatibility, and eliminate interface effect. When the complex films change surface properties, the main body property of polyimide is maintained well.

Description

Preparation method of polyimide siloxane/polyimide double-sided heterosexual composite film

technical field

The invention belongs to the field of macromolecular materials, and in particular relates to a preparation method of a novel polyimide siloxane/polyimide double-sided heterosexual composite film.

Background technique

Polyimide (PI) is widely used in machinery, electronics, aviation and many other fields due to its excellent thermal stability, electrical insulation, physical and mechanical properties and chemical stability. However, its rigid structure leads to insolubility, infusibility, high hygroscopicity and high surface energy, which limit its application in electrical insulating varnishes, buffer coatings, and interlayer packaging materials.

However, silicone resin has good solubility, low water absorption, low dielectric rate, good adhesion and other characteristics. Due to the needs of the development of the electronics and electrical industries, materials such as insulating films, passivation films, and substrates for printed integrated circuits are required to have high adhesion, high and low temperature resistance, and moisture resistance. , blending and other methods to synthesize silicon-containing polyimide resin, combining the characteristics of the two to meet the needs of the market. The surface properties of silicon-containing polyimide resins have been extensively studied, and a low surface energy blend material can be obtained by adding a small amount of polydimethylsiloxane (PDMS) to the homopolymer, but due to the The difference in properties leads to phase separation. Therefore, the researchers designed a block copolymer of polyimide/polydimethylsiloxane (PDMS), in which PDMS is easy to form surface enrichment, because PDMS has The very low surface energy leads to the migration of PDMS to the surface of the material when the material is cured in many polymer systems, forming a surface-rich layer of PDMS without changing the properties of the material host. However, in the application in the aerospace field, the linear expansion coefficient of this block copolymer is quite different from that of other materials, which causes shrinkage between materials and leads to peeling.

Contents of the invention

The purpose of this invention is to provide a kind of preparation method of novel polyimide siloxane/polyimide two-sided heterosexual composite film, one side is polyimide siloxane block copolymer, one side is polyimide amine.

This composite film utilizes polyimide/polydimethylsiloxane block copolymer and pure polyimide (PI) film, which has better compatibility and thus eliminates the interface effect. In addition, the presence of a small amount of polydimethylsiloxane on the surface of the composite film and the large amount of polyimide resin in the main body make the composite film change the surface properties and at the same time improve the host properties of polyimide. Better keep.

The preparation method of the polyimide siloxane/polyimide two-sided heterogeneous composite film involved in the present invention comprises the following three steps: the synthesis of polyimide siloxane block copolymer prepolymer, polyamic acid Synthesis of prepolymer, preparation of polyimide siloxane/polyimide composite film.

(1) Preparation of polyimide siloxane block copolymer prepolymer

The prepolymer of polyimide siloxane block copolymer is based on dianhydride, namely 3,4,3',4'-biphenyltetraacid dianhydride (s-BPDA), 2,3',3,4' - biphenyltetralic dianhydride (a-BPDA), 2,2',3,3'-biphenyltetrapic dianhydride (i-BPDA), diphenyl ether tetrapic dianhydride (ODPA) or pyromellitic acid Dianhydride (PMDA); diamines are 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether (3,4'-ODA), 3, 3'-diaminodiphenyl ether (3,3'-ODA) or 1,4,-(3-aminophenoxy)benzene (1,4,3-APB), the present invention uses aminopropyl-terminated poly Dimethylsiloxane is used as raw material and synthesized with N,N-dimethylacetamide (DMAc), N,N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP) as solvent.

The structural formula of the dianhydride monomer involved in the present invention is as follows:

The structural formula of the diamine monomer involved in the present invention is as follows:

The structural formula of the aminopropyl-terminated polydimethylsiloxane involved in the present invention is as follows:

PDMS p=1, 2, 3, 4, 5, 6, 9

_Mw = 252, 334, 406, 475, 550, 600, 813 g/mol

The specific preparation process of the composite membrane of the present invention is: under magnetic stirring, diamine is weighed and dissolved in N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF ) or N-methylpyrrolidone (NMP), slowly add dianhydride, after the addition is complete, react at room temperature under stirring conditions for 0.5-3 hours; then add aminopropyl-terminated polydimethylsiloxane, and add React for 4-10 hours (experimental results show that 6 hours is better), to obtain the polyimide siloxane block copolymer prepolymer in our design, wherein dianhydride, diamine and aminopropyl terminated polydimethylsiloxane The molar ratio of the base siloxane is 2:1:1, the solid content in the solvent is 8-20%, and the solid content=the mass of the solute in the solvent/(the mass of the solute+the mass of the solvent)%.

The aminopropyl-terminated polydimethylsiloxanes suitable for the above steps can have different degrees of polymerization p=1, 2, 3, 4, 5, 6, and 9, and the corresponding average molecular weights are M _w =252, 334, 406, 475, 550, 600, 813 g/mol.

Only take 3,4,3',4'-biphenyltetraacid dianhydride (s-BPDA) and 4,4'-diaminodiphenyl ether (4,4'-ODA) as examples to describe the polyacrylamide of the present invention below. The preparation method of iminosiloxane block copolymer prepolymer is illustrated, rather than limiting the present invention, and its synthetic reaction formula is as follows:

(2) Preparation of polyamic acid prepolymer

The polyamic acid prepolymer is based on dianhydrides, namely 3,4,3',4'-biphenyl tetra-acid dianhydride (s-BPDA), 2,3',3,4'-biphenyl tetra-acid dianhydride ( a-BPDA), 2,2',3,3'-biphenyltetra-acid dianhydride (i-BPDA), diphenyl ether tetra-acid dianhydride (ODPA) or pyromellitic dianhydride (PMDA), diamine That is, 4,4'-diaminodiphenyl ether (4,4'-ODA), 3,4'-diaminodiphenyl ether (3,4'-ODA), 3,3'-diaminodiphenyl ether (3,3'-ODA) or 1,4,-(3-aminophenoxy)benzene (1,4,3-APB) as raw material, with N,N-dimethylacetamide (DMAc), N , N-dimethylformamide (DMF) or N-methylpyrrolidone (NMP) is synthesized as a solvent.

The specific preparation process includes: under magnetic stirring, diamine is weighed and dissolved in N, N-dimethylacetamide (DMAc), N, N-dimethylformamide (DMF) or N-methylpyrrolidone ( NMP) in the beaker, after diamine dissolves completely, slowly add dianhydride in the beaker; Under stirring state, room temperature reaction 2-6 hour (experimental result shows that 4 hours is better), obtain polyamic acid prepolymer, Wherein the molar ratio of dianhydride and diamine is 1:1, and the concentration of solute in the solvent is 10-40g/ml.

The preparation method of the polyamic acid prepolymer of the present invention is described below only by taking 3,4,3',4'-biphenyltetraacid dianhydride and 4,4'-diaminodiphenyl ether as examples, rather than describing the present invention. The limitation of its synthetic route is shown in the following reaction formula:

(3) Preparation of polyimide siloxane/polyimide double-sided heterosexual composite film

In the present invention, the synthetic method of polyimide siloxane/polyimide two-sided heterosexual composite film is as follows: the polyimide siloxane block copolymer prepolymer and polyamic acid prepolymer synthesized by the above method As a raw material, with tetrahydrofuran (THF) and N, N-dimethylacetamide (or N, N-dimethylformamide or N-methylpyrrolidone) as a mixed solvent, the use of THF with a low boiling point is because PDMS is in The solubility in THF is better, while the solubility of polyamic acid (PAA) in THF is poor, so the PDMS segment in PAA-PDMS is better dissolved in THF. When treated at low temperature, as THF with a low boiling point volatilizes, the PDMS segment in PAA-PDMS migrates to the upper surface of the film along with the solvent volatilization process, thus preparing this polyimide siloxane/polyimide Composite membrane material with amine double-sided anisotropy.

Specific process: We prepared composite films with polyimide siloxane/polyimide ratios of 0.2%, 0.3%, and 0.5%, respectively.

The specific preparation steps are as follows: the polyimide siloxane block copolymer prepolymer prepared in the above steps is dissolved in tetrahydrofuran, and then mixed with the polyamic acid prepolymer (N, N-dimethylacetamide, N, N-dimethylformamide or N-methylpyrrolidone is used in the preparation of polyamic acid prepolymer and polyimide siloxane block copolymer prepolymer in the above steps, in this step No need to add this type of solvent), add 0.05g-0.5g polyimide siloxane block copolymer prepolymer per milliliter of tetrahydrofuran, polyimide siloxane block copolymer prepolymer and The mass ratio of the amount of polyamic acid prepolymer is 0.001-0.01: 1, after making it mix evenly, cast film (also known as cast film) on glass plate; better), and then put it into an oven at 35-45°C and 55-65°C for 1-5 hours respectively (the experimental results show that 3 hours is better); then transfer it to a vacuum oven at 75-85°C and 95°C -105°C, 115-125°C, 145-155°C, 175-185°C, and 245-255°C were treated for 0.5-3 hours (experimental results show that 1 hour is better) for thermal imidization. After the treatment, remove the film from the glass plate, which is the composite film we prepared.

The present invention prepares polyimide siloxane block copolymer prepolymer, and uses this block copolymer to blend with polyamic acid prepolymer, and utilizes similar miscibility principle and each component in the imidization process The polyimide siloxane block copolymer/polyimide bifacial composite film is prepared with different solubility in different solvents. The bifacial composite film can be proved by XPS and water droplet contact angle characterization. The thermal and mechanical properties of it were studied, and the results showed that the composite film has excellent thermal and mechanical properties. Because one side surface of the composite film has the advantages of silicone itself, such as aging resistance, long life, anti-fouling self-cleaning, solvent resistance, excellent adhesion and waterproof, while the other side surface has the excellent thermal properties of polyimide. , mechanical properties and dielectric properties, etc., have broad application prospects in the fields of electronics, chemical industry and so on.

Description of drawings

Figure 1: Schematic diagram of polyimide siloxane/polyimide double-sided heterosexual composite film prepared by the present invention;

Figure 2: Scanning electron microscope image of polyimide siloxane/polyimide double-sided heterogeneous composite film;

(A) is the scanning photo of polyimide siloxane layer;

(B) is a scanned photo of the polyimide layer;

Figure 3: X-photoelectron spectroscopy data of polyimide siloxane/polyimide double-sided heterogeneous composite film;

(A) X-photoelectron spectroscopy data of the air side of polyimide siloxane/polyimide double-sided heterogeneous composite film;

(B) X-photoelectron spectroscopy data of the glass surface of polyimide siloxane/polyimide double-sided heterosexual composite film;

Figure 4: Thermal weight loss temperature curve of polyimide siloxane/polyimide double-sided heterogeneous composite film;

As shown in Figure 1, 1 is a polyimide siloxane layer, and 2 is a polyimide layer.

The composite film in Fig. 2 is the polyimide siloxane prepared from the polyimide siloxane block copolymer prepolymer described in Example 1-1 and the polyamic acid prepolymer described in Example 2-1. Scanning photographs of two-sided heterogeneous composite films with a ratio of 0.5% alkanes and polyimides. As shown in Figure 2, the presence of organic silicon particles can be clearly seen in the scanned photo of the polyimide layer, but no such particles can be seen in the scanned photo of the polyimide layer.

The composite film in Fig. 3 is the polyimide prepared by the polyimide siloxane block copolymer prepolymer described in embodiment 1-1, the polyamic acid prepolymer described in embodiment 2-1 X-ray photoelectron spectroscopy data of a two-sided heterogeneous composite film with a ratio of siloxane and polyimide of 0.2%. (A) and (B) are the X-ray photoelectron spectra of the air surface and the glass surface of the composite film, respectively. It can be seen from the figure: on the air surface, the peak intensity of Si is about 1425, the peak intensity of C is about 15742, the peak intensity of N is about 5310, and the peak intensity of O is about 16012; however, on the glass surface, the peak intensity of Si is about is 1277, the peak intensity of C is about 16912, the peak intensity of N is about 7798, and the peak intensity of O is about 15839. The peak intensities of Si and O are higher on the air side than on the glass side, whereas the peak intensities of C and N are lower on the air side than on the glass side. This is caused by the surface enrichment of polyimide siloxane, the air surface shows a higher content of Si and O due to the presence of more siloxane components, while the lower surface contains more polyimide siloxane. imine components and higher content of C and N. This proves that in the polyimide siloxane/polyimide composite film we synthesized, the surface of polyimide siloxane is enriched, and the two-sided heterogeneity of the composite film is proved.

Table 1 is the contact angle data of polyimide siloxane/polyimide two-sided heterosexual composite film, which is made of the polyimide siloxane block copolymer described in embodiment 1-1. Body, the polyimide siloxane and polyimide prepared by the polyamic acid prepolymer described in Example 2-1 are 0%, 0.2%, 0.3%, 0.5% two-sided heterogeneous composite film. Silicones have good hydrophobic properties, while polyimides are good hydrophilic substances, so the contact angle of water droplets can be used to characterize the distribution of the two substances in the composite film. As can be seen from the data in Table 1, pure polyimide has a smaller water drop contact angle, and as the addition of polyimide siloxane copolymer increases, the water drop contact angle of the air surface of the composite membrane increases, The contact angle of water droplets on the glass surface does not change much. Especially when the content of polyimide siloxane copolymer reaches 0.5%, the change of water drop contact angle on both sides of our synthesized composite membrane is most obvious. This has also explained that in polyimide siloxane block copolymer/polyimide composite film, polyimide siloxane is more enriched in the upper surface (with air interface) of film, makes Its contact angle increases, and the lower surface of the film (the surface in contact with the glass) is more composed of polyimide. Contact angle experiments further proved the two-sided heterogeneity of the composite film.

Table 1: Contact angle data of polyimidesiloxane/polyimide bifacial composite films Polyimide siloxane/polyimide 0% 0.2% 0.3% 0.5% Contact angle Air side 73 92 93 100 Glass side 79 74 83 65

Through the above characterizations, it is proved that the target product—polyimidesiloxane/polyimide composite film has two-sided anisotropy.

Table 2 is the glass transition temperature data of the polyimidesiloxane/polyimide double-sided heterogeneous composite film determined by the DSC scanning method. This composite film is a polyimide silicone prepared from the polyimide siloxane block copolymer prepolymer described in Example 1-1 and the polyamic acid prepolymer described in Example 2-1. Two-sided heterogeneous composite films with 0%, 0.2%, 0.3%, and 0.5% ratios of alkane and polyimide. It can be seen that the glass transition temperature of pure polyimide is 281°C, and this higher glass transition temperature is due to the rigid structure of polyimide. When the content of polyimide siloxane copolymer is 0.2%-0.5%, it can be seen that as the content of polyimide siloxane copolymer increases, the glass transition temperature of its composite film decreases gradually, This is due to the increase in flexible silicon-oxygen bonds. When the content is 0.5%, its glass transition temperature is 272°C. Compared with pure polyimide, the glass transition temperature of this composite membrane material is only 9°C lower, which shows that this composite membrane maintains the excellent high temperature resistance of polyimide.

Table 2: Glass transition temperature data of PI-PDMS/PI two-sided heterogeneous composite film determined by DSC scanning method Polyimide siloxane/polyimide 0% 0.2% 0.3% 0.5% T _g (°C) 281 279 275 272

The composite membrane in Fig. 4 is the polyimide prepared by the polyimide siloxane block copolymer prepolymer described in embodiment 1-1, the polyamic acid prepolymer described in embodiment 2-1. Thermogravimetric curves of two-sided heterogeneous composite films with 0.5% ratio of amine siloxane and polyimide. It can be seen from the figure that the 5% thermal weight loss temperature of pure polyimide is 579 °C, and the carbonization retention rate is 63%; the 5% thermal weight loss temperature of the composite film with a polyimide siloxane content of 0.5% is 564 °C. °C, the carbonization retention rate was 61%. Compared with pure polyimide, its thermal weight loss temperature is only 15°C lower, which shows that this composite membrane material maintains good thermal stability of polyimide.

Table 3 is the data of the mechanical properties of the polyimide siloxane/polyimide two-sided heterogeneous composite film. This composite film is a polyimide silicone prepared from the polyimide siloxane block copolymer prepolymer described in Example 1-1 and the polyamic acid prepolymer described in Example 2-1. Two-sided heterogeneous composite films with 0%, 0.2%, 0.3%, and 0.5% ratios of alkane and polyimide. It can be seen from the data in the table that the modulus remains above 2.8GPa, the tensile strength exceeds 123MPa, and the elongation at break exceeds 17%. Compared with the pure polyimide material, the composite membrane material has basically no change in modulus, the maximum breaking strength is kept above 120MPa, and the elongation at break is also well maintained, which shows that the polyimide silicon oxide The addition of alkane block copolymer did not affect the original excellent mechanical properties of polyimide.

Table 3: Data of mechanical properties of polyimidesiloxane/polyimide bifacial composite films Polyimide siloxane/polyimide Modulus (GPa) Maximum breaking strength (MPa) Elongation at break (%) 0% 0.2% 0.3% 0.5% 2.92.82.82.8 147149170123 36293917

In conclusion, through the structural characterization of the polyimide siloxane/polyimide bifacial composite film, the bifacial property of the composite film is proved. By characterizing the properties of polyimidesiloxane/polyimide double-sided composite film, it is proved that polyimidesiloxane/polyimide double-sided composite film maintains the excellent thermal properties of polyimide. and mechanical properties.

Detailed ways

One, the specific embodiment of polyamic acid prepolymer preparation:

Example 1-1:

Dissolve 0.20mol (40g) of 4,4'-diaminodiphenyl ether in a beaker containing 946mL (889g) of DMAc, and stir under magnetic force until the dissolution of 4,4'-diaminodiphenyl ether is complete , slowly add 0.20mol (58.8g) 3,4,3',4'-biphenyltetraacid dianhydride, after the addition is complete, under airtight conditions, react for 4 hours under magnetic stirring, and obtain 950ml of 10% solid content The slightly pale yellow polyamic acid prepolymer solution A1.

Embodiment 1-2:

The procedure is the same as in Example 1-1, except that the dianhydride monomer is replaced with 0.20mol (58.8g) 2,3',3,4'-biphenyltetraacid dianhydride to obtain 950ml of 10% solid content Slightly yellowish polyamic acid prepolymer solution A2.

Embodiment 1-3:

The procedure is the same as in Example 1-1, except that the dianhydride monomer is replaced with 0.20mol (58.8g) 2,2',3,3'-biphenyltetraacid dianhydride to obtain 950ml of 10% solid content Slightly yellowish polyamic acid prepolymer solution A3.

Embodiment 1-4:

The same steps as in Example 1-1, except that the dianhydride monomer was replaced by 0.20mol (62g) diphenyl ether tetra-acid dianhydride to obtain 950ml of slightly light yellow polyamic acid prepolymerization with a solid content of 10%. Compound solution A4.

Embodiment 1-5:

The same steps as in Example 1-1, except that the dianhydride monomer is replaced by 0.20mol (43.6g) pyromellitic dianhydride to obtain 950ml of slightly light yellow polyamic acid prepolymerization with a solid content of 9%. Compound solution A5.

Embodiment 1-6:

Dissolve 0.20mol (40g) of 3,4'-diaminodiphenyl ether in a beaker containing 946mL of DMAc, under magnetic stirring, after the dissolution of 3,4'-diaminodiphenyl ether, slowly add 0.20mol (58.8g) 3,4,3',4'-biphenyltetralic acid dianhydride, after adding, react under airtight conditions and magnetic stirring for 4 hours to obtain 950ml of 10% solid content slightly Pale yellow polyamic acid prepolymer solution A6.

Embodiment 1-7:

The same steps as in Example 1-6, except that the dianhydride monomer is replaced with 0.20mol (58.8g) 2,3',3,4'-biphenyltetraacid dianhydride to obtain 950ml of 10% solid content Slightly yellowish polyamic acid prepolymer solution A7.

Embodiment 1-8:

The same steps as in Example 1-6, except that the dianhydride monomer is replaced by 0.20mol (58.8g) 2,2',3,3'-biphenyltetraacid dianhydride to obtain 950ml of 10% solid content Slightly yellowish polyamic acid prepolymer solution A8.

Examples 1-9:

Same as the steps of Examples 1-6, except that the dianhydride monomer is replaced by 0.20mol (62g) diphenyl ether tetra-acid dianhydride to obtain 950ml of slightly yellowish polyamic acid prepolymerization with a solid content of 10%. Compound solution A9.

Examples 1-10:

The same as in the steps of Examples 1-6, except that the dianhydride monomer is replaced with 0.20mol (43.6g) pyromellitic dianhydride to obtain 950ml of slightly light yellow polyamic acid prepolymerization with a solid content of 9%. substance solution A10.

Examples 1-11:

Dissolve 0.20mol (40g) of 3,3'-diaminodiphenyl ether in a beaker containing 946mL of DMAc, and under magnetic stirring, after the dissolution of 3,3'-diaminodiphenyl ether, slowly add 0.20mol (58.8g) 3,4,3',4'-biphenyltetralic acid dianhydride, after adding, react under airtight conditions and magnetic stirring for 4 hours to obtain 950ml of 10% solid content slightly Pale yellow polyamic acid prepolymer solution A11.

Examples 1-12:

The same steps as in Example 1-11, except that the dianhydride monomer is replaced by 0.20mol (58.8g) 2,3',3,4'-biphenyltetraacid dianhydride to obtain 950ml of 10% solid content Slightly yellowish polyamic acid prepolymer solution A12.

Examples 1-13:

The same steps as in Example 1-11, except that the dianhydride monomer is replaced by 0.20mol (58.8g) 2,2',3,3'-biphenyltetraacid dianhydride to obtain 950ml of 10% solid content Slightly yellowish polyamic acid prepolymer solution A13.

Examples 1-14:

The same steps as in Example 1-11, except that the dianhydride monomer is replaced by 0.20mol (62g) diphenyl ether tetra-acid dianhydride to obtain 950ml of slightly light yellow polyamic acid prepolymerization with a solid content of 10%. Compound solution A14.

Examples 1-15:

The same steps as in Example 1-11, except that the dianhydride monomer is replaced by 0.20mol (43.6g) pyromellitic dianhydride, to obtain 950ml of slightly light yellow polyamic acid prepolymerization with a solid content of 9%. Compound solution A15.

Examples 1-16:

0.20mol (58.4g) of 1,4,-(3-aminophenoxy)benzene was dissolved in a beaker with 946mL of DMAc, and under magnetic stirring, 1,4,-(3-aminophenoxy After the dissolution of benzene, 0.20mol (58.8g) of 3,4,3',4'-biphenyltetraacid dianhydride was slowly added, and after the addition was completed, the reaction was carried out under airtight conditions and magnetic stirring for 4 hours to obtain 950ml A slightly light yellow polyamic acid prepolymer solution A16 with a solid content of 12%.

Examples 1-17:

The same steps as in Example 1-16, except that the dianhydride monomer is replaced by 0.20mol (58.8g) 2,3',3,4'-biphenyltetraacid dianhydride to obtain 950ml of dianhydride with a solid content of 12%. Slightly yellowish polyamic acid prepolymer solution A17.

Examples 1-18:

The same steps as in Example 1-16, except that the dianhydride monomer is replaced by 0.20mol (58.8g) 2,2',3,3'-biphenyltetraacid dianhydride to obtain 950ml of dianhydride with a solid content of 12%. Slightly yellowish polyamic acid prepolymer solution A18.

Examples 1-19:

The same steps as in Example 1-16, except that the dianhydride monomer is replaced by 0.20mol (62g) diphenyl ether tetra-acid dianhydride to obtain 950ml of slightly yellowish polyamic acid prepolymerization with a solid content of 12%. substance solution A19.

Examples 1-20:

Same as the steps of Examples 1-16, except that the dianhydride monomer is replaced by 0.20mol (43.6g) pyromellitic dianhydride to obtain 950ml of slightly yellowish polyamic acid prepolymerization with a solid content of 10%. substance solution A20.

Examples 1-21:

The procedure was the same as in Example 1-1, except that the solvent DMAc was replaced by DMF to obtain 950 ml of slightly yellowish polyamic acid prepolymer solution A21 with a solid content of 10%.

Examples 1-22:

The procedure was the same as in Example 1-1, except that the solvent DMAc was replaced by NMP to obtain 950 ml of slightly yellowish polyamic acid prepolymer solution A22 with a solid content of 10%.

Two, the specific embodiment of polyimide siloxane block copolymer prepolymer preparation:

Example 2-1:

Under magnetic stirring, dissolve 0.04mol (8g) of 4,4'-diaminodiphenyl ether in a beaker containing 530mL (499.68g) of DMAc, and after the dissolution of 4,4'-diaminodiphenyl ether , slowly add 0.08mol (23.52g) 3,4,3',4'-biphenyltetraic acid dianhydride, after 2 hours of reaction, add 0.04mol (24g) aminopropyl-terminated polydimethylsiloxane (M _w =600g/mol), after the addition is completed, under airtight conditions, react under magnetic stirring for 6 hours to obtain 550ml of a colorless and transparent polyimidesiloxane block copolymer with a solid content of 10%. body solution B1.

Example 2-2:

The same steps as in Example 2-1, except that the dianhydride monomer was replaced with 0.08mol (23.52g) 2,3',3,4'-biphenyltetraacid dianhydride to obtain 550ml of 10% solid content Color transparent polyimide siloxane block copolymer prepolymer solution B2.

Embodiment 2-3:

The procedure is the same as in Example 2-1, except that the dianhydride monomer is replaced with 0.08mol (23.52g) 2,2',3,3'-biphenyltetraacid dianhydride to obtain 550ml of 10% solid content. Pale yellow polyimidesiloxane block copolymer prepolymer solution B3.

Embodiment 2-4:

The same steps as in Example 2-1, except that the dianhydride monomer is replaced by 0.08mol (24.8g) diphenyl ether tetra-acid dianhydride to obtain 550ml of colorless and transparent polyimide silicone with a solid content of 10%. Alkane block copolymer prepolymer solution B4.

Embodiment 2-5:

The procedure is the same as in Example 2-1, except that the dianhydride monomer is replaced with 0.08mol (17.44g) pyromellitic dianhydride to obtain 550ml of a colorless and transparent polyimidesiloxane embedded polyimide with a solid content of 9.5%. Segment copolymer prepolymer solution B5.

Embodiment 2-6:

Under magnetic stirring, dissolve 0.04mol (8g) of 3,4'-diaminodiphenyl ether in a beaker containing 530mL (499.68g) of DMAc, and after the dissolution of 3,4'-diaminodiphenyl ether , slowly add 0.08mol (23.52g) 3,4,3',4'-biphenyltetraic acid dianhydride, after 2 hours of reaction, add 0.04mol (24g) aminopropyl-terminated polydimethylsiloxane (M _w =600g/mol), after the addition is completed, under airtight conditions, react under magnetic stirring for 6 hours to obtain 550ml of a colorless and transparent polyimidesiloxane block copolymer with a solid content of 10%. body solution B6.

Embodiment 2-7:

The same steps as in Example 2-6, except that the dianhydride monomer is replaced by 0.08mol (23.52g) 2,3',3,4'-biphenyltetraacid dianhydride to obtain 550ml of 10% solid content Color transparent polyimide siloxane block copolymer prepolymer solution B7.

Embodiment 2-8:

The steps are the same as in Example 2-6, except that the dianhydride monomer is replaced with 0.08mol (23.52g) 2,2',3,3'-biphenyltetraacid dianhydride to obtain 550ml solid content of 10%. Pale yellow polyimidesiloxane block copolymer prepolymer solution B8.

Embodiment 2-9:

The same steps as in Example 2-6, except that the dianhydride monomer is replaced by 0.08mol (24.8g) diphenyl ether tetra-acid dianhydride to obtain 550ml of colorless and transparent polyimide silicone with a solid content of 10%. Alkane block copolymer prepolymer solution B9.

Embodiment 2-10:

The same steps as in Example 2-6, except that the dianhydride monomer is replaced by 0.08mol (17.44g) pyromellitic dianhydride, to obtain 550ml of a colorless and transparent polyimide siloxane embedded polyimide with a solid content of 9.5%. Segment copolymer prepolymer solution B10.

Example 2-11:

Under magnetic stirring, dissolve 0.04mol (8g) of 3,3'-diaminodiphenyl ether in a beaker containing 530mL (499.68g) of DMAc, and after the dissolution of 3,3'-diaminodiphenyl ether , slowly add 0.08mol (23.52g) 3,4,3',4'-biphenyltetraic acid dianhydride, after 2 hours of reaction, add 0.04mol (24g) aminopropyl-terminated polydimethylsiloxane (M _w =600g/mol), after the addition is completed, under airtight conditions, react under magnetic stirring for 6 hours to obtain 550ml of a colorless and transparent polyimidesiloxane block copolymer with a solid content of 10%. body solution B11.

Embodiment 2-12:

The same steps as in Example 2-11, except that the dianhydride monomer is replaced by 0.08mol (23.52g) 2,3',3,4'-biphenyltetraacid dianhydride to obtain 550ml of 10% solid content Color transparent polyimide siloxane block copolymer prepolymer solution B12.

Example 2-13:

The steps are the same as in Example 2-11, except that the dianhydride monomer is replaced by 0.08mol (23.52g) 2,2',3,3'-biphenyltetraacid dianhydride to obtain 550ml of 10% solid content. Pale yellow polyimidesiloxane block copolymer prepolymer solution B13.

Example 2-14:

The same steps as in Example 2-11, except that the dianhydride monomer is replaced by 0.08mol (24.8g) diphenyl ether tetra-acid dianhydride to obtain 550ml of colorless and transparent polyimide silicone with a solid content of 10%. Alkane block copolymer prepolymer B14.

Embodiment 2-15:

The same steps as in Example 2-11, except that the dianhydride monomer is replaced by 0.08mol (17.44g) pyromellitic dianhydride, to obtain 550ml of colorless and transparent polyimide siloxane with a solid content of 9.5%. Block copolymer prepolymer solution B15.

Example 2-16:

Under magnetic stirring, 0.04mol (11.68g) 1,4,-(3-aminophenoxy)benzene was dissolved in a beaker containing 530mL (499.68g) of DMAc, and 1,4,-(3- After the dissolving of aminophenoxy)benzene, slowly add 0.08mol (23.52g) 3,4,3',4'-biphenyltetraacid dianhydride, after reacting for 2 hours, then add 0.04mol (24g) aminopropyl End-capped polydimethylsiloxane ( _Mw =600g/mol), after the addition is completed, react under airtight conditions and magnetic stirring for 6 hours to obtain 550ml of colorless and transparent polyimide with a solid content of 10%. Silicone Block Copolymer Prepolymer Solution B16.

Example 2-17:

The same steps as in Example 2-16, except that the dianhydride monomer is replaced with 0.08mol (23.52g) 2,3',3,4'-biphenyltetraacid dianhydride to obtain 550ml of 10% solid content Color transparent polyimide siloxane block copolymer prepolymer solution B17.

Example 2-18:

The steps are the same as in Example 2-16, except that the dianhydride monomer is replaced with 0.08mol (23.52g) 2,2',3,3'-biphenyltetraacid dianhydride to obtain 550ml of 10% solid content. Pale yellow polyimidesiloxane block copolymer prepolymer solution B18.

Example 2-19:

The same steps as in Example 2-16, except that the dianhydride monomer is replaced by 0.08mol (24.8g) diphenyl ether tetra-acid dianhydride, to obtain 550ml of colorless and transparent polyimide silicone with a solid content of 11%. Alkane block copolymer prepolymer solution B19.

Embodiment 2-20:

Same as the steps of Example 2-16, except that the dianhydride monomer is replaced by 0.08mol (17.44g) pyromellitic dianhydride, to obtain 550ml of colorless and transparent polyimide siloxane with a solid content of 10%. Block copolymer prepolymer solution B20.

Example 2-21:

The procedure was the same as in Example 2-1, except that the solvent DMAc was replaced by DMF to obtain 550 ml of a colorless and transparent polyimidesiloxane block copolymer prepolymer solution B21 with a solid content of 10%.

Example 2-22:

The procedure was the same as in Example 2-1, except that the solvent DMAc was replaced by NMP to obtain 550 ml of a colorless and transparent polyimidesiloxane block copolymer prepolymer solution B22 with a solid content of 10%.

Example 2-23:

The procedure is the same as in Example 2-1, except that 0.04 mol (24 g) of aminopropyl-terminated polydimethylsiloxane (M _w =600 g/mol) is replaced by 0.04 mol (10.08 g) of aminopropyl-terminated polydimethylsiloxane Polydimethylsiloxane (M _w =252 g/mol) to obtain 550 ml of a colorless and transparent polyimidesiloxane block copolymer prepolymer solution B23 with a solid content of 8%.

Example 2-24:

The procedure is the same as in Example 2-1, except that 0.04 mol (24 g) of aminopropyl-terminated polydimethylsiloxane (M _w =600 g/mol) is replaced by 0.04 mol (13.36 g) of aminopropyl-terminated polydimethylsiloxane Polydimethylsiloxane (M _w =334 g/mol) to obtain 550 ml of a colorless and transparent polyimidesiloxane block copolymer prepolymer solution B24 with a solid content of 8%.

Example 2-25:

The procedure is the same as in Example 2-1, except that 0.04 mol (24 g) of aminopropyl-terminated polydimethylsiloxane (M _w =600 g/mol) is replaced by 0.04 mol (16.24 g) of aminopropyl-terminated polydimethylsiloxane Polydimethylsiloxane (M _w =406 g/mol) to obtain 550 ml of a colorless and transparent polyimidesiloxane block copolymer prepolymer solution B25 with a solid content of 9%.

Example 2-26:

The same procedure as in Example 2-1, except that 0.04 mol (24 g) of aminopropyl-terminated polydimethylsiloxane (M _w =600 g/mol) was replaced by 0.04 mol (19 g) of aminopropyl-terminated polydimethylsiloxane Dimethylsiloxane (M _w =475g/mol) to obtain 550ml of a colorless and transparent polyimidesiloxane block copolymer prepolymer solution B26 with a solid content of 9%.

Example 2-27:

The same procedure as in Example 2-1, except that 0.04 mol (24 g) of aminopropyl-terminated polydimethylsiloxane (M _w =600 g/mol) was replaced by 0.04 mol (22 g) of aminopropyl-terminated polydimethylsiloxane Dimethyl siloxane (M _w =550 g/mol) to obtain 550 ml of a colorless and transparent polyimide siloxane block copolymer prepolymer solution B27 with a solid content of 9.6%.

Example 2-28:

The procedure is the same as in Example 2-1, except that 0.04 mol (24 g) of aminopropyl-terminated polydimethylsiloxane (M _w =600 g/mol) is replaced by 0.04 mol (32.52 g) of aminopropyl-terminated polydimethylsiloxane Polydimethylsiloxane (M _w =813g/mol) to obtain 550ml of a colorless and transparent polyimidesiloxane block copolymer prepolymer solution B28 with a solid content of 11%.

3. The specific implementation of the preparation of polyimide siloxane/polyimide double-sided heterosexual composite film:

Example 3-1:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B1 and dissolve them in 1mL of tetrahydrofuran, and mix them with 50g of polyamic acid prepolymer A1. Polyimidesiloxane The proportions of the block copolymer prepolymer and the polyamic acid prepolymer were 0.2%, 0.3%, and 0.5%, respectively, and then film was coated on a glass plate. Leave it at room temperature for 1 hour, and then put it into an oven at 40°C and 60°C for 3 hours respectively. Then transfer to a vacuum oven for 1 hour at 80°C, 100°C, 120°C, 150°C, 180°C, and 250°C for thermal imidization. After the treatment, the film is removed from the glass plate, which is the composite film we prepared. The obtained composite film has good transparency and heat resistance.

Example 3-2:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B2 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A2. The method is the same as in Example 3-1. . The obtained composite film has better heat resistance and mechanical properties than the composite film of Example 3-1.

Embodiment 3-3:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B3 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A3. The method is the same as in Example 3-1. . The obtained composite film has better heat resistance but poorer mechanical properties than the composite film of Example 3-1.

Embodiment 3-4:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B4 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A4. The method is the same as in Example 3-1. . The obtained composite film was inferior in heat resistance to the composite film of Example 3-1.

Embodiment 3-5:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B5 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A5. The method is the same as in Example 3-1. . The obtained composite film had better heat resistance than the composite film of Example 3-1.

Embodiment 3-6:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B6 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A6. The method is the same as in Example 3-1. . The obtained composite membrane has better mechanical properties than the composite membrane of Example 3-1.

Embodiment 3-7:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B7 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A7. The method is the same as in Example 3-1. . The obtained composite membrane has better mechanical properties than the composite membrane of Example 3-1.

Embodiment 3-8:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B8 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A8. The method is the same as in Example 3-1. . The obtained composite film had better heat resistance than the composite film of Example 3-1.

Embodiment 3-9:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B9 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A9. The method is the same as in Example 3-1. . The obtained composite film had poorer heat resistance than the composite film of Example 3-1, but better transparency.

Embodiment 3-10:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B10 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A10. The method is the same as in Example 3-1. . The obtained composite film had better heat resistance than the composite film of Example 3-1.

Embodiment 3-11:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B11 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A11. The method is the same as in Example 3-1. . The obtained composite film had better transparency than the composite film of Example 3-1.

Embodiment 3-12:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B12 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A12. The method is the same as in Example 3-1. . The obtained composite film had better heat resistance and transparency than the composite film of Example 3-1.

Embodiment 3-13:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B13 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A13. The method is the same as in Example 3-1. . The obtained composite film had better transparency but poorer mechanical properties than the composite film of Example 3-1.

Embodiment 3-14:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B14 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A14. The method is the same as in Example 3-1. . The obtained composite film had better transparency but poorer heat resistance than the composite film of Example 3-1.

Embodiment 3-15:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B15 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A15. The method is the same as in Example 3-1. . The obtained composite film had better transparency and heat resistance than the composite film of Example 3-1.

Example 3-16:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B16 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A16. The method is the same as in Example 3-1. . The obtained composite membrane was inferior to the composite membrane of Example 3-1 in heat resistance but lower in water absorption.

Embodiment 3-17:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B17, dissolve them in 1mL of tetrahydrofuran, and mix them with 50g of polyamic acid prepolymer A17. The method is the same as in Example 3-1. . The obtained composite membrane has better mechanical properties and lower water absorption than the composite membrane of Example 3-1.

Embodiment 3-18:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B18 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A18. The method is the same as in Example 3-1. . Compared with the composite membrane obtained in Example 3-1, the obtained composite membrane has poorer mechanical properties but lower water absorption.

Example 3-19:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B19, dissolve them in 1mL of tetrahydrofuran, and mix them with 50g of polyamic acid prepolymer A19. The method is the same as in Example 3-1. . The obtained composite membrane was inferior to the composite membrane of Example 3-1 in heat resistance but lower in water absorption.

Embodiment 3-20:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B20, dissolve them in 1mL of tetrahydrofuran, and mix them with 50g of polyamic acid prepolymer A20. The method is the same as in Example 3-1. . The obtained composite membrane was inferior to the composite membrane of Example 3-1 in heat resistance but lower in water absorption.

Example 3-21:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B21 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A21. The method is the same as in Example 3-1. . The obtained composite film has good transparency and heat resistance.

Embodiment 3-22;

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B22, dissolve them in 1mL of tetrahydrofuran, and mix them with 50g of polyamic acid prepolymer A22. The method is the same as in Example 3-1. . The obtained composite film has good transparency and heat resistance.

Embodiment 3-23;

The steps are the same as in Example 3-1, except that the treatment time at 40°C and 60°C is changed to 1 hour. The above film was tested, and the data showed that this film did not have good dihedral properties compared with Example 3-1, which may be caused by the shorter time of low temperature treatment and the shorter movement time of siloxane segments .

Embodiment 3-24;

The steps are the same as in Example 3-1, except that the temperature is placed on a heating plate at 40°C and 60°C. A composite film with poor uniformity was obtained because the localized heating of the process on the hot plate made the film uniformity poor.

Embodiment 3-25:

The steps are the same as in Example 3-1, except that no tetrahydrofuran is added during the mixing process. The above film was tested, and the data showed that the film did not have good dihedral properties compared with Example 3-1. This may be because both polyimide siloxane and polyimide are dissolved in the same solvent, and there is no difference in the solubility of polyimide siloxane and polyimide during the solvent volatilization process, so it does not reach a very high level. Good separation effect.

Example 3-26:

The steps are the same as in Example 3-1, except that the film is coated on a stainless steel plate. The above film was tested, and the data showed that the film had no good double-sided property compared with Example 3-1. This may be because when polyimide siloxane and polyimide are coated on the stainless steel plate, there is a certain force between the polysiloxane and the stainless steel plate, so the two-sided anisotropy of the composite film is not obvious.

Example 3-27:

The steps are the same as in Example 3-1, except that the film is placed on the aluminum foil during the high temperature treatment. The above film was tested, and the data showed that the film had no good double-sided property compared with Example 3-1. This may be because the polyimide siloxane and polyimide are placed on the aluminum foil, and there is a certain reaction between the polysiloxane and the aluminum foil during high temperature treatment, so the two-sided anisotropy of the composite film is not obvious. In addition, the curling of the aluminum foil during high temperature treatment also caused the inhomogeneity of the composite film.

Example 3-28:

The steps are the same as in Example 3-1, except that a disk is covered on the top when it is placed at room temperature, and the disk is removed when it is transferred to high temperature treatment. A composite film with poor uniformity is obtained, because when it is processed at low temperature, it is processed under airtight conditions, and the solvent cannot volatilize, so it will have a certain impact on the film when it flows down. Therefore, the non-uniformity of the film is caused.

Example 3-29:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B23, dissolve them in 1mL of tetrahydrofuran, and mix them with 50g of polyamic acid prepolymer A1. The method is the same as in Example 3-1. . The resulting composite film had poor diplexity. This is because the polyimide siloxane with a shorter chain segment is not conducive to its movement in the imide chain segment, resulting in poor two-sided property of the film.

Example 3-30:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B24 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A1. The method is the same as in Example 3-1. . A composite film with poor dihedrality similar to that in Examples 3-29 was obtained. This is because the polyimide siloxane with a shorter chain segment is not conducive to its movement in the imide chain segment, resulting in poor two-sided property of the film.

Example 3-31:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B25 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A1. The method is the same as in Example 3-1. . A composite film with poor dihedrality similar to that in Examples 3-28 was obtained. This is because the polyimide siloxane with a shorter chain segment is not conducive to its movement in the imide chain segment, resulting in poor two-sided property of the film.

Example 3-32:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B26, dissolve them in 1mL of tetrahydrofuran, and mix them with 50g of polyamic acid prepolymer A1. The method is the same as in Example 3-1. . A composite film with poor dihedrality similar to that in Examples 3-28 was obtained. This is because the polyimide siloxane with a shorter chain segment is not conducive to its movement in the imide chain segment, resulting in poor two-sided property of the film.

Example 3-33:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B27 and dissolve them in 1mL of tetrahydrofuran, and then mix them with 50g of polyamic acid prepolymer A1. The method is the same as in Example 3-1. . A composite film with poor dihedrality similar to that in Examples 3-28 was obtained. This is because the polyimide siloxane with a shorter chain segment is not conducive to its movement in the imide chain segment, resulting in poor two-sided property of the film.

Example 3-34:

Take 0.1g, 0.15g, and 0.25g of polyimidesiloxane block copolymer prepolymer B28, dissolve them in 1mL of tetrahydrofuran, and mix them with 50g of polyamic acid prepolymer A1. The method is the same as in Example 3-1. . A composite film with better two-sided anisotropy similar to Example 3-1 was obtained. This is because the chain segment of polyimidesiloxane is long enough to facilitate its movement in the imide chain segment, thus obtaining a film with better two-sided anisotropy.

Claims (4)

1. A method for preparing polyimidesiloxane/polyimide double-sided heterosexual composite film, including the synthesis of polyimidesiloxane block copolymer prepolymer and the synthesis of polyamic acid prepolymer 3 steps for the preparation of polyimide siloxane/polyimide composite film, characterized in that: (1) Under magnetic stirring, weigh diamine and dissolve it in a beaker with an organic solvent, slowly add dianhydride, after the addition is complete, react at room temperature for 0.5-3 hours under stirring conditions; Methyl siloxane, add and react for 4-10 hours to obtain polyimide siloxane block copolymer prepolymer, in which dianhydride, diamine and aminopropyl-terminated polydimethylsiloxane The molar ratio is 2:1:1, and the solid content is 8-20%; (2) Under magnetic stirring, weigh diamine and dissolve it in a beaker equipped with an organic solvent. After the diamine is completely dissolved, slowly add dianhydride to the beaker; under stirring, react at room temperature for 2-6 hours to obtain A polyamic acid prepolymer, wherein the molar ratio of dianhydride and diamine is 1:1, and the solid content is 8-20%; (3) Dissolve the polyimidesiloxane block copolymer prepolymer prepared in the above steps in tetrahydrofuran, then mix it with the polyamic acid prepolymer, and add 0.05g-0.5g of polyamic acid per milliliter of tetrahydrofuran Imide siloxane block copolymer prepolymer, the mass ratio of polyimide siloxane block copolymer prepolymer to polyamic acid prepolymer is 0.001-0.01:1, so that it can be mixed evenly Finally, cast a film on a glass plate; let it stand at room temperature for 0.5-3 hours, then put it in an oven at 35-45°C and 55-65°C for 1-5 hours respectively; then transfer it to a vacuum oven at 75°C -85°C, 95-105°C, 115-125°C, 145-155°C, 175-185°C, 245-255°C respectively for 0.5-3 hours for thermal imidization, after the treatment, remove from the glass plate The film is polyimide siloxane/polyimide double-sided heterosexual composite film; The diamine in the above steps is 4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether, 3,3'-diaminodiphenyl ether or 1,4,-(3-amino Phenoxy) one of benzene; dianhydride is 3,4,3',4'-biphenyltetraacid dianhydride, 2,3',3,4'-biphenyltetraacid dianhydride, 2,2 One of ', 3, 3'-biphenyltetra-acid dianhydride, diphenyl ether tetra-acid dianhydride or pyromellitic dianhydride; the organic solvent is N,N-dimethylformamide, N,N- One of dimethylacetamide or N-methylpyrrolidone. 2. The preparation method of polyimide siloxane/polyimide double-sided heterosexual composite film as claimed in claim 1, characterized in that: dianhydride, diamine and aminopropyl-terminated polydimethylsiloxane The polymerization reaction time for preparing the polyimidesiloxane block copolymer prepolymer from alkane is 6 hours. 3. The preparation method of polyimide siloxane/polyimide double-sided heterosexual composite film as claimed in claim 1, characterized in that: the polymerization reaction time of dianhydride and diamine to prepare polyamic acid prepolymer is 4 hours. 4. The preparation method of polyimide siloxane/polyimide double-sided heterosexual composite film as claimed in claim 1, characterized in that: the time for standing at room temperature after casting film on a glass plate is 1 hour, Put it in an oven at 35-45°C and 55-65°C for 3 hours, then transfer it to a vacuum oven at 75-85°C, 95-105°C, 115-125°C, 145-155°C , 175-185°C, and 245-255°C are respectively treated for 1 hour.

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