Core-shell nanoparticle / dynamic polyurea composites for synergistic toughening and glass transition temperature enhancement

Abstract

The application discloses a kind of synergistic toughening and improving glass transition temperature core-shell nanoparticles / dynamic polyimide composite, the formula of the composite includes matrix phase polyimide resin and reinforcing phase polymer core-shell nanoparticles.Preferred raw materials include p-xylylene, triamine crosslinking agent, diamine, polymer core-shell nanoparticles and the like.The preparation route includes: first, polymer core-shell nanoemulsion is phase transferred or directly core-shell nanoparticles are compounded with dynamic polyimide polymer material to modify, the toughness, glass transition temperature and contact angle size of modified dynamic polymer material are significantly improved.The application provides a new means for the composite modification of dynamic polyimide material, and is expected to further broaden and deepen its application in resin matrix, composite and other fields.

Description

Technical Field

[0001] This invention relates to the field of dynamic polymer composite material synthesis technology, and in particular to a formulation and preparation of a polymer core-shell nanoparticle modified polyimide composite material. Background Technology

[0002] Dynamically cross-linked polymers (VCPs) are a class of polymers with unique properties, characterized by their dynamic cross-linking structures that can break and recombine under specific conditions. This gives them unique properties such as self-healing, shape memory, and reprocessability. Among the many dynamic chemical bonds, imine bonds are a type of reversible dynamic covalent bond. Their polymerization reaction conditions are mild, and changes in external temperature, humidity, and pH can cause the imine bonds to undergo dissociation or non-dissociation dynamic interactions. Reversible cross-linked polymers based on imine bonds show interesting application potential and high recycling value in various fields. Although dynamic polyimide cross-linked polymers have demonstrated many advantages, their dynamic nature often poses challenges to environmental stability, including mechanical properties, glass transition temperature, and hydrophobicity, which greatly limits their application potential.

[0003] Polymer core-shell nanoparticles are a class of structured and functionalized composite particles composed of at least two different chemical components, exhibiting a bilayer or multilayer structure. As a structured composite particle, the bilayer or multilayer structure of polymer core-shell nanoparticles enables them to possess a variety of functions and applications. By adjusting the composition, size, and morphology of the core and shell, the properties of polymer core-shell nanoparticles can be precisely controlled, thus playing an important role in fields such as biomedicine, catalysts, sensors, and energy storage. However, the formulation and application of polymer core-shell nanoparticles in the field of dynamic polymers have not been reported. This invention combines polymer core-shell nanoparticles with dynamic polyimide to prepare a polymer core-shell nanoparticle-toughened polyimide composite material, which exhibits significant synergistic toughening and improved glass transition temperature effects compared to the polyimide matrix, and also shows improved hydrophobicity. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of insufficient mechanical properties and inadequate temperature resistance of dynamic polymers, and to broaden their application fields. To this end, we provide a formulation and preparation method for a polymer core-shell nanoparticle-toughened polyimide composite material.

[0005] The objective of this invention is achieved through the following technical solution:

[0006] A core-shell nanoparticle / dynamic polyimide composite material that synergistically toughens and improves the glass transition temperature includes the following preparation steps and formulation design:

[0007] Step S1: Add terephthalaldehyde to an organic solvent and stir for a certain time at a certain temperature to ensure complete dissolution. Step S2: Add a fluorene-containing diamine monomer to the solution and stir to dissolve at a certain temperature. Step S3: Add polymer core-shell nanoparticles to the solution in a specific form and proportion, and disperse and stir until homogeneous. Step S4: Finally, add a triamine crosslinking agent to form a dynamic crosslinking network. After stirring for a certain time, pour the solution into a glass petri dish, dry it in a forced-air oven, and then place it in a vacuum oven for post-curing crosslinking to obtain a core-shell toughened polyimide composite material.

[0008] Further: the organic solvent in step S1 is one or a mixture of several of N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, and chloroform, the certain temperature is 0-40 ℃, and the certain time is 5-30 min.

[0009] Further: the fluorene-containing diamine in step S2 is one or a mixture of several of 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, and 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene. The specified temperature is 0-40 °C, the mass of the added core-shell particles is 5-40% of the theoretical mass of the synthesized polyimide, and the specified time is 0.5-3 h.

[0010] Further: The preparation method of the polymer core-shell nanoparticle-reinforced polyimide composite material according to claim 1 is characterized in that: the polymer core-shell in step S3 is one or more composites of polymethyl methacrylate as the shell, polybutyl acrylate as the core, a polymer copolymerized from butyl acrylate and methyl methacrylate as the shell, and octamethylcyclotetrasiloxane as the core, or Japanese Kanekachi M722, M521, and MX-125 type polymer core-shells. The doping state of the micro / nano core-shell particles is powder after emulsion demulsification and drying, or flocculent material after phase inversion of the emulsion. The doping ratio of polymer core-shell particles is 0.01%-50%.

[0011] Further: The triamine crosslinking agent mentioned in step S4 is one or a mixture of two of tris(2-aminoethyl)amine and trimethylolpropane tripropylene glycol ether (amino-terminated), and the mixture is stirred for a certain time of 30-300 s. The temperature of the forced-air drying oven is 60-80 ℃, and the drying time is 12-72 h. The temperature of the vacuum oven is 100-160 ℃, and the curing time is 0.5-5 h.

[0012] The polyimide composite material obtained by the above preparation method is a polyimide composite material toughened by polymer core-shell nanoparticles. Compared with the uncomposite polyimide material, the polyimide composite material toughened by polymer core-shell nanoparticles has significantly improved toughness, glass transition temperature, and hydrophobicity, exhibiting outstanding substantial characteristics and significant progress.

[0013] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0014] Introducing polymer core-shell nanoparticles via phase transfer offers a significant advantage over traditional blending methods. Phase transfer effectively disperses the core-shell particles and polymers, preventing particle aggregation and buildup. It typically operates under mild reaction conditions, such as room temperature and without the need for high pressure. In contrast, traditional blending requires higher temperatures or shear forces, while phase transfer has lower requirements for the thermal stability of the reactants. Furthermore, phase transfer offers strong selectivity and controllability, allowing for the manipulation of particle size, dispersion, and morphology. This selectivity and controllability make it advantageous in fields such as nanoparticles and polymer composites.

[0015] The polymer-core-shell nanoparticle-reinforced polyimide composite material prepared in this invention exhibits improved fracture toughness, glass transition temperature, and hydrophobicity. The fracture toughness is 3.3 MJ / m compared to the polyimide resin matrix. 3 It increased to 5.2 MJ / m 3 The glass transition temperature increased from 80 °C to 105 °C compared to the comparative example, an increase of 25 °C, and the water contact angle also increased by about 10 degrees, representing a significant improvement in performance. Attached Figure Description

[0016] Figure 1 This is a photograph of the core-shell emulsion after phase transfer prepared in Example 1.

[0017] Figure 2 This is a photograph of the polymer core-shell nanoparticle-reinforced polyimide composite material prepared in Example 1.

[0018] Figure 3 The infrared characteristic peak spectra of the polymer core-shell nanoparticle-reinforced polyimide composites prepared in Examples 1, 2, and 3 are shown. (1639 cm⁻¹) -1 The characteristic peak of the dynamic imine bond at 1560 cm⁻¹ -1 The characteristic peaks of the aromatic benzene ring at 1750 cm⁻¹ all confirm the successful synthesis of the polyimide resin matrix. -1 The C=O stretching vibration peak at that point proves the introduction of core-shell particles.

[0019] Figure 4 The bar chart shows the water contact angle of the polymer core-shell nanoparticle-toughened polyimide composites prepared in Examples 1, 2, and 3 as a function of time. Compared to the water contact angle of the polyimide resin matrix in the comparative examples, the water contact angle of the composites increased by approximately 10°.

[0020] Figure 5 The images show the scanning calorimetry (DSC or DMA) plots of the polymer core-shell nanoparticle-reinforced polyimide composites prepared in Examples 1, 2, and 3. Compared to the polyimide resin matrix of the comparative examples before composite formation, the glass transition temperatures of the polyimide composites in Examples 1, 2, and 3 after composite formation were significantly increased by 22 °C, 23 °C, and 25 °C, respectively.

[0021] Figure 6 The figures show a comparison of the stress-strain properties of the polymer core-shell nanoparticle-toughened polyimide composites prepared in Examples 1, 2, and 3. Compared to the polyimide resin of the comparative examples before composite preparation, the fracture toughness of the polyimide composite films of Examples 1, 2, and 3 after composite preparation increased by 9%, 10%, and 58%, respectively. Detailed Implementation

[0022] To better understand the present invention, the technical solution of the present invention will be further described below with reference to the embodiments and accompanying drawings, but the implementation of the present invention is not limited thereto. Example

[0023] 0.805 g of terephthalaldehyde (6 mmol) and 16.8 g of N-methylpyrrolidone solvent were added to a 100 mL beaker. After magnetic stirring at 25 °C for 10 min, the terephthalaldehyde was completely dissolved. Then, 1.045 g of 9,9-bis(4-aminophenyl)fluorene (2 mmol) was added and stirred for 10 min until dissolved. Finally, 0.292 g of crosslinking agent tris(2-aminoethyl)amine (2 mmol) and 2 g of N-methylpyrrolidone were added to the beaker, and stirring was continued at room temperature for 1 min. The mixture was then poured into a glass petri dish and placed in a 70 °C oven for solvent evaporation for 48 h. After that, it was placed in a 150 °C vacuum oven for curing for 1 h to finally obtain the polyimide resin matrix (Cardo-DPI).

[0024] Figure 3 The infrared characteristic peak spectrum of the polymer core-shell nanoparticle modified polyimide composite material prepared in the comparative example is shown.

[0025] Figure 4 The bar chart shows the change in water contact angle over time for the polymer core-shell nanoparticle modified polyimide composite material prepared in the comparative examples.

[0026] Figure 5The scanning calorimetry (DSC or DMA) curves of the polymer core-shell nanoparticle modified polyimide composite material prepared in the comparative examples are shown.

[0027] Figure 6 The stress-strain curves of the polymer core-shell nanoparticle modified polyimide composite material prepared for the comparative examples are shown. Example 1

[0028] Phase transfer of the core-shell emulsion: 6.8 g of butanone (MEK) was added to a beaker, followed by 5 g of the core-shell emulsion, and the mixture was stirred until homogeneous (10 min). Then, 8 g of deionized water was added and stirring was continued for 30 min. After standing for 30 min, phase separation was observed. The lower aqueous layer was filtered to obtain the polymer core-shell nanoparticles after phase transfer.

[0029] Figure 1 This is a photograph of the core-shell emulsion after phase transfer prepared in Example 1.

[0030] 0.805 g of terephthalaldehyde (6 mmol) and 16.8 g of N-methylpyrrolidone solvent were added to a 100 mL beaker. After magnetic stirring at 25 °C for 10 min, the terephthalaldehyde was completely dissolved. Then, 1.045 g of 9,9-bis(4-aminophenyl)fluorene (2 mmol) was added and stirred for 10 min until dissolved. Next, 0.193 g of phase-transferred core-shell particles (10 wt%) were added and stirring was continued for 2 h. Finally, 0.292 g of crosslinking agent tris(2-aminoethyl)amine (2 mmol) and 2 g of N-methylpyrrolidone were added to the beaker, and stirring was continued at room temperature for 1 min. The mixture was then poured into a glass petri dish and placed in a 70 °C oven for solvent evaporation for 48 h. After that, it was removed and placed in a 150 °C vacuum oven for curing for 1 h, finally obtaining the polymer core-shell nanoparticle-toughened polyimide composite material (Cardo-DPI+10% CS).

[0031] Figure 2 This is a photograph of the polymer core-shell nanoparticle-reinforced polyimide composite material prepared in Example 1.

[0032] Figure 3 The infrared characteristic peak spectrum is shown for the polymer core-shell nanoparticle-reinforced polyimide composite material prepared in Example 1.

[0033] Figure 4 The bar chart shows the change in water contact angle over time for the polymer core-shell nanoparticle-toughened polyimide composite material prepared in Example 1.

[0034] Figure 5 The image shows a scanning calorimetry (DSC or DMA) diagram of the polymer core-shell nanoparticle-reinforced polyimide composite material prepared in Example 1.

[0035] Figure 6 The image shows the stress-strain curve of the polymer core-shell nanoparticle-toughened polyimide composite material prepared in Example 1. Example 2

[0036] The phase transfer process of the polymer core-shell nanoparticles is the same as in Example 1.

[0037] 0.805 g of terephthalaldehyde (6 mmol) and 18.8 g of N-methylpyrrolidone solvent were added to a 100 mL beaker. After magnetic stirring at 25 °C for 10 min, the terephthalaldehyde was completely dissolved. Then, 1.045 g of 9,9-bis(4-aminophenyl)fluorene (2 mmol) was added and stirred for 10 min until dissolved. Next, 0.385 g of the phase-transferred core-shell particles (20 wt%) were added and stirring was continued for 2 h. Finally, 0.292 g of the crosslinking agent tris(2-aminoethyl)amine (2 mmol) and 2 g of N-methylpyrrolidone were added to the beaker, and stirring was continued at room temperature for 1 min. The mixture was then poured into a glass petri dish and placed in a 70 °C oven for solvent evaporation for 48 h. After that, it was placed in a 150 °C vacuum oven for curing for 1 h, finally obtaining the polymer core-shell nanoparticle-toughened polyimide composite material (Cardo-DPI+20% CS).

[0038] Figure 3 The infrared characteristic peak spectrum of the polymer core-shell nanoparticle-reinforced polyimide composite material prepared in Example 2 is shown.

[0039] Figure 4 The bar chart shows the change in water contact angle over time for the polymer core-shell nanoparticle-toughened polyimide composite material prepared in Example 2.

[0040] Figure 5 The image shows a scanning calorimetry (DSC or DMA) diagram of the polymer core-shell nanoparticle-reinforced polyimide composite material prepared in Example 2.

[0041] Figure 6 The image shows the stress-strain curve of the polymer core-shell nanoparticle-toughened polyimide composite material prepared in Example 2. Example 3

[0042] The phase transfer process of the polymer core-shell nanoparticles is the same as in Example 1.

[0043] 0.805 g of terephthalaldehyde (6 mmol) and 20.5 g of N-methylpyrrolidone solvent were added to a 100 mL beaker. After magnetic stirring at 25 °C for 10 min, the terephthalaldehyde was completely dissolved. Then, 1.045 g of 9,9-bis(4-aminophenyl)fluorene (2 mmol) was added and stirred for 10 min until dissolved. Next, 0.578 g of phase-transferred core-shell particles (20 wt%) were added and stirring was continued for 2 h. Finally, 0.292 g of crosslinking agent tris(2-aminoethyl)amine (2 mmol) and 2 g of N-methylpyrrolidone were added to the beaker, and stirring was continued at room temperature for 1 min. The mixture was then poured into a glass petri dish and placed in a 70 °C oven for solvent evaporation for 48 h. After that, it was placed in a 150 °C vacuum oven for curing for 1 h, finally obtaining the polymer core-shell nanoparticle-toughened polyimide composite material (Cardo-DPI+30% CS).

[0044] Figure 3 The infrared characteristic peak spectrum of the polymer core-shell nanoparticle-reinforced polyimide composite material prepared in Example 4 is shown.

[0045] Figure 4 The bar chart shows the change in water contact angle over time for the polymer core-shell nanoparticle-toughened polyimide composite material prepared in Example 4.

[0046] Figure 6 The image shows the stress-strain curve of the polymer core-shell nanoparticle-toughened polyimide composite material prepared in Example 4. Example 4

[0047] The phase transfer process of the polymer core-shell nanoparticles is the same as in Example 1.

[0048] 0.805 g of terephthalaldehyde (6 mmol) and 17.9 g of N-methylpyrrolidone solvent were added to a 100 mL beaker. After magnetic stirring at 25 °C for 10 min, the terephthalaldehyde was completely dissolved. Then, 1.045 g of 9,9-bis(4-aminophenyl)fluorene (2 mmol) was added and stirred for 10 min until dissolved. Next, 0.289 g of phase-transferred core-shell particles (15 wt%) were added and stirring was continued for 2 h. Finally, 0.292 g of crosslinking agent tris(2-aminoethyl)amine (2 mmol) and 2 g of N-methylpyrrolidone were added to the beaker, and stirring was continued at room temperature for 1 min. The mixture was then poured into a glass petri dish and placed in a 70 °C oven for solvent evaporation for 48 h. After that, it was placed in a 150 °C vacuum oven for curing for 1 h, finally obtaining the polymer core-shell nanoparticle-toughened polyimide composite material (Cardo-DPI+15% CS). Example 5

[0049] 0.805 g of terephthalaldehyde (6 mmol) and 17.9 g of N-methylpyrrolidone solvent were added to a 100 mL beaker. After magnetic stirring at 25 °C for 10 min, the terephthalaldehyde was completely dissolved. Then, 1.045 g of 9,9-bis(4-aminophenyl)fluorene (2 mmol) was added and stirred for 10 min until dissolved. Next, 0.193 g of core-shell powder (10 wt%) after emulsion demulsification was added and stirring was continued for 2 h. Finally, 0.292 g of crosslinking agent tris(2-aminoethyl)amine (2 mmol) and 2 g of N-methylpyrrolidone were added to the beaker, and stirring was continued at room temperature for 1 min. The mixture was then poured into a glass petri dish and placed in a 70 °C oven for solvent evaporation for 48 h. After that, it was placed in a 150 °C vacuum oven for curing for 1 h, finally obtaining a polymer core-shell nanoparticle-toughened polyimide composite material (Cardo-DPI+15% CS).

Claims

1. A method for preparing a polymer core-shell nanoparticle-reinforced polyimide composite material, characterized in that, Specifically, the following steps are included: S1: Add terephthalaldehyde to an organic solvent, and stir for a certain time at a certain temperature to ensure that the terephthalaldehyde is completely dissolved in the organic solvent; S2: Add the diamine monomer containing fluorene to the solution and stir to dissolve it at a certain temperature; S3: Polymer core-shell nanoparticles are added to the solution in a certain form and proportion and dispersed and stirred evenly; the polymer core-shell is one or more composites of polymethyl methacrylate as shell and polybutyl acrylate as core, or Japanese Kanebuchi M722, M521, MX-125 type polymer core-shell; the mass of the added core-shell nanoparticles is 5-40% of the theoretical mass of the synthesized polyimide; S4: Finally, add the triamine crosslinking agent to form a dynamic crosslinking network. After stirring for a certain period of time, pour the solution into a glass petri dish, dry it in a forced-air oven, and then place it in a vacuum oven for curing and crosslinking to obtain the core-shell toughened polyimide composite material.

2. The method for preparing the polymer core-shell nanoparticle-reinforced polyimide composite material according to claim 1, characterized in that: The organic solvent in step S1 is one or a mixture of several of N-methylpyrrolidone, dimethyl sulfoxide, N,N-dimethylacetamide, N,N-dimethylformamide, and chloroform; the specific temperature is 0-40 °C; and the specific time is 5-30 min.

3. The method for preparing the polymer core-shell nanoparticle-reinforced polyimide composite material according to claim 1, characterized in that: The fluorene-containing diamine in step S2 is one or a mixture of more of the following: 9,9-bis(4-aminophenyl)fluorene, 9,9-bis(3-fluoro-4-aminophenyl)fluorene, and 9,9-bis[4-(4-aminophenoxy)phenyl]fluorene, and the specific temperature is 0-40 °C.

4. The method for preparing the polymer core-shell nanoparticle-reinforced polyimide composite material according to claim 1, characterized in that: The triamine crosslinking agent mentioned in S4 is one or a mixture of two of tris(2-aminoethyl)amine and trimethylolpropane tripropylene glycol ether (amino-terminated), and the stirring time is 30-300 s; the temperature of the forced-air drying oven is 60-80 ℃, and the drying time is 12-72 h; the temperature of the vacuum oven is 100-160 ℃, and the curing time is 0.5-5 h.

5. A polymer core-shell nanoparticle modified polyimide composite material obtained by the preparation method according to any one of claims 1-4.

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