A method for preparing water-soluble polyimide nanohybrid material

Abstract

The present invention relates to the technical field of polyimide materials, and particularly to a method for preparing a high-temperature resistant, water-soluble polyimide nanohybrid material. This method involves optimizing monomer selection, selecting 1,4-cyclohexanediamine (DACH) and ethylenediaminetetraacetic dianhydride (EDTA) as polyimide monomers to prepare a PAA / NMP solution. Secondly, heptaphenyl caged polysilsesquioxane trisilanol (POSS) is modified with a γ-aminopropyltriethoxysilane (KH550) coupling agent to prepare amino-modified KH550-POSS nanoparticles. Finally, the amino-modified KH550-POSS nanoparticles are uniformly mixed with the PAA / NMP solution and imidized to produce a water-soluble polyimide (PI) nanohybrid material. This method is simple and easy to implement, and the resulting polyimide hybrid material can be water-soluble and repeatedly molded, exhibiting significantly improved high-temperature resistance and mechanical properties.

Description

Technical Field

[0001] The present invention relates to the technical field of polyimide materials, in particular to a method for preparing a water-soluble polyimide nano-hybrid material. Background Art

[0002] Polyimide (PI) materials offer excellent thermal and dimensional stability, along with superior mechanical and dielectric properties, and are widely used in high-tech fields such as aerospace, transportation, and microelectronics. Currently, commonly used PI resins contain a conjugated aromatic ring structure, offering excellent overall performance. However, these resins are difficult to reprocess and their products are difficult to recycle, resulting in resource waste and environmental pollution.

[0003] By introducing large asymmetric, flexible, and polar groups into the PI molecular structure, the solubility of PI in common organic solvents such as N,N-dimethylformamide (DMF), N-methylpyrrolidone (NMP), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and dichloromethane (DCM) can be improved, enabling the recycling of PI material products. However, the large amount of organic solvents used in the PI regeneration process is associated with safety and environmental risks.

[0004] The regeneration process of water-soluble PI materials uses water as a solvent, avoiding the pollution problems of organic solvents and having the significant advantage of being green and environmentally friendly. Therefore, the development of water-soluble and easily regenerated PI resins has important positive significance for conserving resources and reducing carbon emissions.

[0005] At present, the chain structure of water-soluble PI mostly contains long aliphatic chains, which has certain deficiencies in high temperature resistance and mechanical properties, and cannot effectively meet the needs of widespread application in high temperature environments. Summary of the Invention

[0006] The present invention aims to address the technical problems identified in the aforementioned background technology by providing a method for preparing a water-soluble PI nanohybrid material. This method is simple and easy to implement, and the resulting PI nanohybrid material is water-soluble and can be repeatedly molded, while exhibiting significantly improved high-temperature resistance and mechanical properties.

[0007] Specifically, the present invention adopts the following technical solutions:

[0008] A method for preparing a water-soluble polyimide nanohybrid material comprises the following steps:

[0009] (1) Add 0.1 mol of 1,4-cyclohexanediamine (DACH) to 100-150 mL of NMP and stir evenly to obtain a DACH / NMP solution. Then, slowly add 0.05-0.2 mol of ethylenediaminetetraacetic dianhydride (EDTA) to the obtained DACH / NMP solution and react in an ice bath under a nitrogen atmosphere for more than 24 hours to prepare a PAA / NMP solution.

[0010] (2) Disperse 0.001-0.01 mol of heptaphenyl caged polysilsesquioxane trisilanol (POSS) in 10-100 mL of NMP, then add 0.001-0.05 mol of γ-aminopropyltriethoxysilane (KH550) coupling agent, react at 20-30 ° C for 2 hours, centrifuge and wash, and then freeze-dry to obtain amino-terminated modified KH550-POSS nanoparticles;

[0011] (3) The amino-terminated KH550-POSS nanoparticles were added to the PAA / NMP solution and stirred to mix evenly. The resulting mixed solution was then coated on a glass plate and treated at 70 °C for 30-60 min to remove the organic solvent. The mixture was then thermally imidized at 150 °C for 3 hours. After complete cooling, the mixture was peeled off from the glass plate to obtain a water-soluble PI nanohybrid material. The thickness of the water-soluble PI nanohybrid material was controlled to be 10-50 μm.

[0012] Preferably, in step (1), the molar ratio of DACH to EDTA is 1:0.5-2.

[0013] Preferably, the amount of NMP added in step (1) is such that the PAA / NMP concentration is 0.2-0.4 g / mL.

[0014] Preferably, the molar ratio of POSS to KH550 in step (2) is 1:1-5.

[0015] Preferably, the amount of amino-terminated modified KH550-POSS nanoparticles added in step (3) is 1-25% of the mass of PAA.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] The preparation method provided by the present invention does not require complicated equipment, the process is simple and easy, and the required raw materials are cheap and easy to manufacture;

[0018] The preparation method of the present invention prepares water-soluble PI nanohybrid materials, which not only solves the problem that traditional PI cannot be recycled and reused, but also avoids the occurrence of environmental pollution caused by the large-scale use of organic solvents in the recycling process;

[0019] The present invention uses aliphatic ring diamine monomers, which significantly improve the mechanical properties of the prepared PI compared to the aliphatic long-chain diamine monomers used in existing water-soluble PIs.

[0020] In the present invention, by introducing modified KH550-POSS nanoparticles (KH550-POSS), the uniform dispersion of KH550-POSS in the polyimide matrix is ​​achieved, while the high temperature resistance and mechanical properties of the polyimide nanohybrid material are improved;

[0021] The material prepared by the present invention can be applied to the fields of novel coatings, microelectronics, functional films, etc., and has a wide potential market. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Scanning electron microscopy (SEM) images of amino-terminated KH550-POSS nanoparticles.

[0023] Figure 2 This is a SEM photograph of the cross section of the water-soluble KH550-POSS / PI nanohybrid material in Example 1.

[0024] Figure 3 This is a SEM photograph of the cross section of the water-soluble KH550-POSS / PI nanohybrid material in Example 2.

[0025] Figure 4 This is a SEM photograph of the cross section of the water-soluble KH550-POSS / PI nanohybrid material in Example 3.

[0026] Figure 5 This is the SEM photo of the cross section of the water-soluble PI material in Comparative Example 1.

[0027] Figure 6 This is the SEM photo of the cross section of the water-soluble POSS / PI nanohybrid material in Comparative Example 2. DETAILED DESCRIPTION

[0028] Representative embodiments will now be further refined. It should be understood that the following description is not intended to limit the embodiments to a preferred embodiment. On the contrary, it is intended to encompass alternatives, modifications, and equivalents that may be included within the spirit and scope of the embodiments defined by the appended claims.

[0029] Example 1:

[0030] A method for preparing a water-soluble polyimide nanohybrid material, the preparation method comprising:

[0031] (1) Add 0.1 mol of DACH to 120 mL of NMP and stir evenly to obtain a DACH / NMP solution. Then, slowly add 0.1 mol of EDTA to the obtained DACH / NMP solution and react in an ice bath under a nitrogen atmosphere for more than 24 hours to prepare a PAA / NMP solution.

[0032] (2) 0.002 mol of POSS was dispersed in 20 mL of NMP, and then 0.006 mol of KH550 was added. The mixture was reacted at 25 °C for 2 hours, washed by centrifugation, and freeze-dried to obtain amino-terminated KH550-POSS nanoparticles. The microscopic morphology of the nanoparticles is shown in FIG. Figure 1 shown.

[0033] (3) The amino-terminated modified KH550-POSS nanoparticles were added to the PAA / NMP solution and stirred to mix evenly. The resulting mixed solution was then coated on a glass plate and treated at 70 °C for 30 min to remove the organic solvent. The mixture was then thermally imidized at 150 °C for 3 hours. After cooling completely, the mixture was peeled off from the glass plate to obtain a water-soluble PI nanohybrid material. The thickness of the water-soluble PI nanohybrid material was controlled to be 30 μm. The cross-sectional micromorphology of the material is shown in FIG. Figure 2 .

[0034] Example 2:

[0035] A method for preparing a water-soluble polyimide nanohybrid material, the preparation method comprising:

[0036] (1) Add 0.1 mol of DACH to 120 mL of NMP and stir evenly to obtain a DACH / NMP solution. Then, slowly add 0.1 mol of EDTA to the obtained DACH / NMP solution and react in an ice bath under a nitrogen atmosphere for more than 24 hours to prepare a PAA / NMP solution.

[0037] (2) 0.004 mol of POSS was dispersed in 20 mL of NMP, and then 0.012 mol of KH550 was added. The mixture was reacted at 25°C for 2 hours, washed by centrifugation, and freeze-dried to obtain amino-terminated KH550-POSS nanoparticles.

[0038] (3) The amino-terminated modified KH550-POSS nanoparticles were added to the PAA / NMP solution and stirred to mix evenly. The resulting mixed solution was then coated on a glass plate and treated at 70°C for 30 min to remove the organic solvent. The mixture was then thermally imidized at 150°C for 3 hours. After complete cooling, the mixture was peeled off from the glass plate to obtain a water-soluble PI nanohybrid material. The thickness of the water-soluble PI nanohybrid material was controlled to be 30 μm. The cross-sectional micromorphology of the material is shown in FIG. Figure 3 .

[0039] Example 3:

[0040] A method for preparing a water-soluble polyimide nanohybrid material, the preparation method comprising:

[0041] (1) Add 0.1 mol of DACH to 120 mL of NMP and stir evenly to obtain a DACH / NMP solution. Then, slowly add 0.1 mol of EDTA to the obtained DACH / NMP solution and react in an ice bath under a nitrogen atmosphere for more than 24 hours to prepare a PAA / NMP solution.

[0042] (2) 0.006 mol of POSS was dispersed in 20 mL of NMP, and then 0.018 mol of KH550 was added. The mixture was reacted at 25 °C for 2 h, washed by centrifugation, and freeze-dried to obtain amino-terminated KH550-POSS nanoparticles.

[0043] (3) The amino-terminated modified KH550-POSS nanoparticles were added to the PAA / NMP solution and stirred to mix evenly. The resulting mixed solution was then coated on a glass plate and treated at 70 °C for 30 min to remove the organic solvent. The mixture was then thermally imidized at 150 °C for 3 hours. After complete cooling, the mixture was peeled off from the glass plate to obtain a water-soluble PI nanohybrid material. The thickness of the water-soluble PI nanohybrid material was controlled to be 30 μm. The cross-sectional micromorphology of the material is shown in FIG. Figure 4 .

[0044] Comparative Example 1:

[0045] A method for preparing a water-soluble polyimide nanohybrid material, the preparation method comprising:

[0046] (1) Add 0.1 mol of DACH to 120 mL of NMP and stir evenly to obtain a DACH / NMP solution. Then, slowly add 0.1 mol of EDTA to the obtained DACH / NMP solution and react in an ice bath under a nitrogen atmosphere for more than 24 hours to prepare a PAA / NMP solution.

[0047] (2) The PAA / NMP solution was coated on a glass plate, first treated at 70 °C for 30 min to remove the organic solvent, and then thermally imidized at 150 °C for 3 hours. After complete cooling, it was peeled off from the glass plate to obtain a water-soluble PI. The thickness of the water-soluble PI material was controlled to be 30 μm, and its cross-sectional micromorphology was as follows: Figure 5 .

[0048] Comparative Example 2:

[0049] A method for preparing a water-soluble polyimide nanohybrid material, the preparation method comprising:

[0050] (1) Add 0.1 mol of DACH to 120 mL of NMP and stir evenly to obtain a DACH / NMP solution. Then, slowly add 0.1 mol of EDTA to the obtained DACH / NMP solution and react in an ice bath under a nitrogen atmosphere for more than 24 hours to prepare a PAA / NMP solution.

[0051] (2) 0.004 mol of unmodified POSS was dispersed in 20 mL of NMP, then added to the PAA / NMP solution and stirred to mix evenly. The obtained mixed solution was coated on a glass plate, first treated at 70 °C for 30 min to remove the organic solvent, and then thermally imidized at 150 °C for 3 hours. After complete cooling, it was peeled off from the glass plate to obtain a water-soluble PI nanohybrid material. The thickness of the water-soluble PI nanohybrid material was controlled to be 30 μm, and its cross-sectional micromorphology was as follows: Figure 6 .

[0052] The water-soluble PI nanohybrid materials obtained in Examples 1-3 and Comparative Examples 1-2 were subjected to performance tests as shown in the following methods.

[0053] Thermogravimetric analysis: Tests were conducted under a nitrogen atmosphere over a temperature range of 25–800°C at a heating rate of 10°C / min. The temperature at which the sample decomposed and lost 5% of its mass was recorded as the decomposition starting temperature. Results are shown in Table 1.

[0054] Mechanical properties test: Tested according to GB / T1040.3-2006, material size 10 mm (length) × 1 mm (width), material thickness 30 μm, test speed 10 mm / min. Results refer to Table 1.

[0055] Regeneration Performance Test: PI samples were immersed in sufficient deionized water and left at room temperature for 24 hours to observe whether they dissolved. The solution was then recast and dried into a film. The mechanical properties were tested, and the tensile strength before and after regeneration was compared to calculate the regeneration performance retention rate. The results are shown in Table 2.

[0056] Table 1 High temperature resistance and mechanical properties of the water-soluble PI nanohybrid materials prepared in Examples 1-3 and Comparative Examples 1-2.

[0057]

[0058] Table 2 Regeneration performance of water-soluble PI nanohybrid materials prepared in Examples 1-3 and Comparative Examples 1-2.

[0059]

[0060] As shown in Table 1, the tensile strength of the PI material with 10% POSS added (Comparative Example 2) decreased by 11.8% compared to the pure PI material (Comparative Example 1), reaching only 53.1 MPa, while the elastic modulus was slightly improved. Furthermore, due to the excellent heat resistance of POSS nanoparticles, the addition of POSS to PI has a certain effect on improving the material's high-temperature resistance. The initial decomposition temperature of the material obtained in Comparative Example 2 increased by 26.4°C to 276.6°C.

[0061] By modifying POSS, KH550-POSS nanoparticles were produced and used to hybrid-modify polyimide (PI) materials. The resulting PI nanohybrid material exhibited improved mechanical properties and high-temperature resistance. For example, the nanohybrid PI material containing 10% KH550-POSS (Example 2) achieved an initial decomposition temperature of 305.9°C, an elastic modulus of 1.78 GPa, and a tensile strength of 88.3 MPa, all significantly improved compared to the PI material containing an equal amount of unmodified POSS (Comparative Example 2). Comparison of nanohybrid PI materials containing varying amounts of KH550-POSS (Examples 1-3) revealed that the addition of 10% KH550-POSS resulted in the PI material with the best overall performance, taking into account material preparation costs.

[0062] Table 2 is the regeneration performance of Examples 1-3 and Comparative Examples 1-2. As can be seen from Table 2: the PI nano hybrid materials obtained from all Examples and Comparative Examples all have good water solubility, and the regeneration performance retention rate is all above 92%. In comparison, the regeneration performance of the water-soluble PI nano hybrid material modified with KH550-POSS nanoparticles has been improved to a certain extent, reaching more than 96%, with better regeneration performance.

[0063] As can be seen from Table 1 and Table 2, the water-soluble PI nanohybrid material prepared in the present invention exhibits high high temperature resistance, mechanical properties and excellent regeneration performance.

[0064] Figure 1 The amino-terminated KH550-POSS nanoparticles have excellent heat resistance. Figure 1 It can be seen that the modified KH550-POSS nanoparticles have good uniformity.

[0065] Figure 2-Figure 4 The cross-sectional view of the water-soluble PI material in which the amount of KH550-POSS nanoparticles modified by amino end capping in Examples 1-3 is 5%, 10%, and 15% of the mass of PAA. Figure 2-Figure 4As can be seen from the figure, as the amount of KH550-POSS nanoparticles added increases, the KH550-POSS nanoparticles are evenly distributed in the water-soluble PI, and the amount of nanoparticles distributed increases significantly with the addition amount. The uniform distribution of nanoparticles is beneficial for improving the high-temperature resistance and mechanical properties of PI materials. The appropriate amount of nanoparticles added can achieve the best improvement effect.

[0066] Figure 5 This is a cross-sectional view of pure water-soluble PI material without nano-hybridization. Figure 5 It can be seen that its cross section is relatively smooth.

[0067] Figure 6 is the cross section of the water-soluble PI material with unmodified POSS added. Figure 6 It can be seen that the unmodified POSS shows typical agglomeration phenomenon in the cross section of the PI material and cannot be well dispersed in the PI material, which easily leads to a decrease in the mechanical properties of the material.

[0068] It is obvious to those skilled in the art that certain modifications, combinations and variations can be made based on the above teachings.

Claims

1. A method for preparing a water-soluble polyimide nanohybrid material, characterized in that: The following steps are involved: (1) Add 0.1 mol of 1,4-cyclohexanediamine to 100-150 mL of N-methylpyrrolidone and stir evenly to obtain a 1,4-DACH / NMP solution. Then, slowly add 0.05-0.2 mol of ethylenediaminetetraacetic dianhydride to the obtained 1,4-DACH / NMP solution and react in an ice bath under a nitrogen atmosphere for more than 24 hours to prepare a PAA / NMP solution. (2) Disperse 0.001-0.01 mol of heptaphenyl caged polysilsesquioxane trisilanol in 10-100 mL of NMP, then add 0.001-0.05 mol of γ-aminopropyltriethoxysilane (KH550) coupling agent, react at 20-30 °C for 2 hours, centrifuge and wash, and then freeze-dry to obtain amino-terminated modified KH550-POSS nanoparticles; (3) The amino-terminated modified KH550-POSS nanoparticles were added to the PAA / NMP solution and stirred to mix evenly. The resulting mixed solution was then coated on a glass plate and treated at 70 °C for 30-60 min to remove the organic solvent. The mixture was then thermally imidized at 150 °C for 3 hours. After complete cooling, the mixture was peeled off from the glass plate to obtain a water-soluble polyimide (PI) nanohybrid material. The thickness of the water-soluble PI nanohybrid material was controlled to be 10-50 μm. In step (1), the molar ratio of 1,4-cyclohexanediamine to ethylenediaminetetraacetic dianhydride is 1:0.5-2; The amount of NMP added in step (1) is such that the PAA / NMP concentration is 0.2-0.4 g / mL; In step (2), the molar ratio of heptaphenyl caged polysilsesquioxane trisilanol to KH550 is 1:1-5; In step (3), the amount of amino-terminated modified KH550-POSS nanoparticles added is 1-25% of the mass of PAA.

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