Preparation method of strong and tough composite material film capable of self-repairing at room temperature

Abstract

The application discloses a preparation method of a room-temperature self-repairable tough composite material film, which comprises the following steps: 1) preparing an aldehyde group-containing functional monomer from a carboxybenzaldehyde monomer, 4-dimethylaminopyridine p-toluenesulfonate and hydroxyethyl methacrylate; the molar ratio of the carboxybenzaldehyde monomer to the 4-dimethylaminopyridine p-toluenesulfonate is 1:1, and the mass ratio of the carboxybenzaldehyde monomer to the hydroxyethyl methacrylate is 1:1-1:2; 2) synthesizing an aldehyde group-containing polymer from the aldehyde group-containing functional monomer in step 1) and an acrylic monomer at a molar ratio of 1:9-2:8; and 3) mixing amino nanoparticles and the aldehyde group-containing polymer obtained in step 2) to form a film, wherein the mass content of the amino nanoparticles is 0.1%-5%. The material can repair the damaged part at room temperature when the material is damaged and broken, and the performance of the material can be restored.

Description

Technical Field

[0001] This invention belongs to the field of repair materials and relates to a method for preparing a strong and tough composite film that can self-heal at room temperature. Background Technology

[0002] Polymer materials are prone to irreversible damage during use due to exposure to light, heat, and mechanical forces. This not only affects the material's lifespan and causes significant economic losses but also reduces its performance reliability and poses safety hazards. Inspired by the ability of many organisms in nature to spontaneously repair themselves after injury, scientists have developed self-healing capabilities in synthetic materials to extend their lifespan and improve their performance reliability. Self-healing materials can repair their own structure and function after damage, either under external stimuli or spontaneously, reducing maintenance costs and significantly extending their lifespan. They have been widely applied in fields such as flexible wearable devices, tissue engineering, and adhesives. Self-healing materials can be divided into exogenous and intrinsic self-healing. Intrinsic self-healing, due to its ability to repair damage multiple times, has received increasing attention. The repair of intrinsic self-healing materials mainly relies on the opening and reconstruction of reversible non-covalent or covalent bonds and the high mobility of polymer chain segments. However, polymer materials with these two characteristics often exhibit poor mechanical strength, severely limiting their practical applications. Therefore, preparing polymer materials with both high mechanical strength and excellent repair properties is a significant challenge. Currently, some strong and tough self-healing materials have been developed (CN115947922A; CN115850953A). However, the repair process of these materials generally requires additional external stimuli such as light and heat, which limits their application range to some extent. Here, we report a method for preparing a room-temperature self-healing strong and tough composite film. Utilizing the reversible Schiff bond interaction between aldehyde-containing polymers and amino nanoparticles, this method not only effectively improves the mechanical properties of the self-healing material but also enables room-temperature self-healing, providing a feasible solution for preparing strong and tough self-healing materials. Summary of the Invention

[0003] In view of this, the present invention provides a method for preparing a strong and tough composite film that can self-heal at room temperature.

[0004] The present invention specifically provides the following technical solution:

[0005] A method for preparing a room-temperature self-healing, tough composite film, comprising the following steps:

[0006] 1) A functional monomer containing an aldehyde group is prepared by using carboxybenzaldehyde monomers, 4-dimethylaminopyridine p-toluenesulfonate and hydroxyethyl methacrylate; wherein the molar ratio of the carboxybenzaldehyde monomers and 4-dimethylaminopyridine p-toluenesulfonate is 1:1 and the mass ratio of the carboxybenzaldehyde monomers and hydroxyethyl methacrylate is 1:1 to 1:2.

[0007] 2) The aldehyde-containing functional monomers and acrylic monomers from step 1) are combined in a molar ratio of 1:9-2:8 to synthesize aldehyde-containing polymers;

[0008] 3) Mix the amino nanoparticles and the aldehyde-containing polymer obtained in step 2) to form a film, wherein the mass content of the amino nanoparticles is 0.1%-5%.

[0009] Furthermore, the carboxybenzaldehyde monomers mentioned in step 1) include one or more of 2-carboxybenzaldehyde, 3-carboxybenzaldehyde, and 4-carboxybenzaldehyde.

[0010] Furthermore, the mass content of the amino nanoparticles in step 3) is 0.2% to 5%.

[0011] Further, the amino nanoparticles mentioned in step 3) are one or more of amino ceramic particles, amino silica, amino iron tetroxide, amino carbon dots, and amino carbon nanotubes.

[0012] Furthermore, the acrylic monomers mentioned in step 2) include one or more of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, and n-octyl acrylate.

[0013] Further, step 1) involves dissolving carboxybenzaldehyde, 4-dimethylaminopyridine p-toluenesulfonate, and a dehydrating agent in a first solvent, then adding a hydroxyethyl methacrylate solution dropwise to the above solution to react and obtain the product. The product is then extracted by rotary evaporation, followed by the sequential addition of a second, third, and fourth solvent, and then rotary evaporation again to obtain the aldehyde-containing functional monomer. The reaction temperature is 20–100°C, the reaction time is 10–24 h, the rotary evaporation temperature is 25–55°C, and the rotary evaporation time is 0.5–1 h.

[0014] Further, step 2) involves mixing the aldehyde-containing functional monomer and the initiator, adding them to the fifth solvent and stirring until homogeneous, then passing an inert gas through to remove oxygen, heating the reaction, and adding the resulting polymer solution to the sixth solvent for sedimentation, centrifugation, and drying to obtain the aldehyde-containing polymer. The deoxygenation time is 30–60 min, the heating temperature is 50–100 °C, the reaction time is 1–48 h, the drying temperature is 40–90 °C, and the drying time is 10–36 h.

[0015] Further, step 3) involves dispersing amino nanoparticles in the seventh solvent to prepare a nanoparticle dispersion, dissolving the aldehyde-containing polymer in the eighth solvent to prepare an aldehyde-containing polymer solution, mixing the nanoparticle dispersion and the aldehyde-containing polymer solution, placing them in a mold to form a film, and obtaining a polymer film that can be repaired at room temperature.

[0016] Further, the dehydrating agent in step 1) comprises dicyclohexylcarbodiimide, N,N-diisopropylcarbodiimide, and (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; the first solvent in step 1) is one or more of chloroform, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, and N,N-dimethylacetamide; the second solvent is one or more of diethyl ether, ethyl acetate, butyl acetate, and hydrochloric acid; the third solvent is one or more of sodium bicarbonate, sodium carbonate, and sodium hydroxide; and the fourth solvent is saturated saline solution or deionized water.

[0017] Further, the initiator in step 2) includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, lauroyl peroxide, and diisopropyl peroxide dicarbonate; the molar ratio of acrylic monomer to initiator is 200:1-500:1; the fifth solvent includes one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, xylene, and petroleum ether; the sixth solvent includes one or more of deionized water, methanol, and ethanol.

[0018] Furthermore, the seventh solvent mentioned in step 3) includes one or more of methanol, ethanol, and deionized water; the eighth solvent includes one or more of tetrahydrofuran, N,N-dimethylformamide, and chloroform.

[0019] The beneficial effects of this invention are as follows: This invention provides a novel method for preparing a strong and tough composite film capable of repairing at room temperature. This material can repair damaged areas and restore its properties at room temperature when damaged or fractured. Due to the high density of van der Waals forces in acrylate bonds, the material possesses softness and room-temperature repair capabilities. Furthermore, the aldehyde groups in the polymer can react with amino-containing nanoparticles through a Schiff base reaction to form dynamic imine bonds, which can improve the material's mechanical properties while maintaining its self-healing ability. However, when the content of amino silica is too high, the self-healing performance of the composite material decreases due to the introduction of too many crosslinking points. Therefore, it is necessary to select an appropriate feed ratio to obtain a material that combines excellent mechanical properties and self-healing capabilities. Attached Figure Description

[0020] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the following figures are provided:

[0021] Figure 1 The 1H NMR spectrum of the aldehyde monomer obtained in step 1) of Example 1 of this invention.

[0022] Figure 2 The 1H NMR spectrum of the aldehyde-containing copolymer obtained in step 2) of Example 3 of this invention.

[0023] Figure 3 The mechanical property spectrum of a room-temperature self-healing, tough composite film.

[0024] Figure 4 The image shows the repair performance spectrum of the room-temperature self-healing, tough composite film prepared in Example 1 of this invention.

[0025] Figure 5 The mechanical property spectrum of the room-temperature self-healing, tough composite film prepared in Comparative Example 5 of this invention is shown.

[0026] Figure 6 This is a digital photograph of the room-temperature self-healing, tough composite film obtained in Example 2 of the present invention after repair.

[0027] Figure 7 This is a digital photograph of the gelation process obtained by adding excess amino silica in Comparative Example 1 of the present invention.

[0028] Figure 8 This is a digital photograph of the pure polybutyl acrylate obtained in Comparative Example 3 of this invention.

[0029] Figure 9 The mechanical property spectra of the room-temperature self-healing, tough composite films prepared in Examples 5 and 4 of this invention are shown. Detailed Implementation

[0030] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0031] Example 1

[0032] (1) Synthesis of aldehyde-containing monomers: 22.2 g of p-carboxybenzaldehyde, 20.05 g of hydroxyethyl methacrylate, and 30 g of N,N-diisopropylcarbodiimide were dissolved in dichloromethane by mass. Then, 3.0 g of 4-dimethylaminopyridine p-toluenesulfonate was added. The mixture was reacted at 30 °C for 20 h. After the reaction was completed, the mixture was rotary evaporated. The reaction product was dissolved in a mixture of ethyl acetate and 2 mol / L hydrochloric acid. The mixture was then extracted twice with 2 mol / L hydrochloric acid. After that, it was extracted three times with 1 mol / L sodium carbonate solution. Finally, it was extracted once with saturated brine. The mixture was rotary evaporated at 50 °C for 0.5 h to obtain a transparent, viscous, yellow oily liquid, which is the aldehyde-containing functional monomer.

[0033] The 1H NMR spectrum of functional monomers containing aldehyde groups is shown below. Figure 1 As shown. From Figure 1 The results show that the chemical shift at 10.05 ppm belongs to the hydrogen atom on the aldehyde group attached to the benzene ring, the chemical shifts at 8.14 ppm and 7.90 ppm belong to the hydrogen atom on the benzene ring, and the chemical shift at 5.50 ppm belongs to the hydrogen atom on the methylene group in the carbon-carbon double bond. These NMR results demonstrate the successful synthesis of the aldehyde-containing functional monomer.

[0034] (2) Preparation of aldehyde-containing polymer materials: 8 mmol of ethyl acrylate, 2 mmol of the aldehyde-containing functional monomer obtained in step (1), and 5 μmol of benzoyl peroxide were mixed in chloroform and stirred until homogeneous. The mixture was then degassed and deoxygenated by freezing for 40 min, heated to 60 °C, and reacted for 24 h. The resulting polymer solution was then settled in a mixed solvent of methanol and water, centrifuged, and placed in a vacuum oven at 70 °C for 12 h. Aldehyde-containing polymer materials were obtained.

[0035] (3) Preparation of a room-temperature self-healing polymer film: 0.005 g of amino silica was dispersed in ethanol to prepare a solution, and 0.995 g of the aldehyde-containing polymer obtained in step (2) was dissolved in chloroform to prepare a solution. The two were mixed and vortexed to form a homogeneous solution. The solution was placed in a polytetrafluoroethylene mold to evaporate the solvent and form a film. After the solvent evaporated, the film was placed in a vacuum drying oven at 0.08 MPa for 24 h. A strong and tough composite film X1 capable of room-temperature repair was obtained. In this step, the mass content of amino silica was 0.2%.

[0036] The mechanical properties and repair performance curves of the room-temperature repairable polymer film X1 are shown in the figure. Figure 4 As shown, curve 1 is the stress-strain curve of composite material X1, with a maximum tensile strength of 2.2 MPa. Curve 2 is the stress-strain curve of composite material X1 after 24 hours of repair at room temperature, with a maximum tensile strength of 1.9 MPa after repair. After the sample in this embodiment was broken, it was butt-jointed and repaired at 25°C for 24 hours, showing good self-healing performance with a repair efficiency of 86.3%.

[0037] Example 2

[0038] (1) Synthesis of aldehyde-containing monomers: 22.2 g of p-carboxybenzaldehyde, 25.4 g of hydroxyethyl methacrylate, and 30 g of N,N-diisopropylcarbodiimide were dissolved in dichloromethane by mass. Then, 3.0 g of 4-dimethylaminopyridine p-toluenesulfonate was added. The mixture was reacted at 30 °C for 20 h. After the reaction was completed, the mixture was rotary evaporated. The reaction product was dissolved in a mixture of ethyl acetate and 2 mol / L hydrochloric acid. The mixture was then extracted twice with 2 mol / L hydrochloric acid. After that, it was extracted three times with 1 mol / L sodium carbonate solution. Finally, it was extracted once with saturated brine. The mixture was rotary evaporated at 50 °C for 0.5 h to obtain a transparent, viscous, yellow oily liquid, which is the aldehyde-containing functional monomer.

[0039] (2) Preparation of aldehyde-containing polymer materials: 8 mmol of ethyl acrylate, 2 mmol of the aldehyde-containing functional monomer obtained in step (1), and 5 μmol of benzoyl peroxide were mixed in N,N-dimethylacetamide and stirred until homogeneous. The mixture was then degassed and deoxygenated by freezing for 40 min, heated to 60 °C, and reacted for 24 h. The resulting polymer solution was then settled in a mixed solvent of methanol and water, centrifuged, and placed in a vacuum oven at 70 °C for 12 h. Aldehyde-containing polymer materials were obtained.

[0040] (3) Preparation of a room-temperature self-healing polymer film: 0.005 g of amino silica was dispersed in ethanol to prepare a solution, and 0.995 g of the aldehyde-containing polymer obtained in step (2) was dissolved in chloroform to prepare a solution. The two were mixed and vortexed to form a homogeneous solution. The solution was placed in a polytetrafluoroethylene mold to evaporate the solvent and form a film. After the solvent evaporated, the film was placed in a vacuum drying oven at 0.08 MPa for 24 h to obtain a room-temperature self-healing, strong composite material X2. The mass content of amino silica was 0.5%.

[0041] Example 3

[0042] (1) Synthesis of aldehyde-containing monomers: 22.2 g of p-carboxybenzaldehyde, 27.05 g of hydroxyethyl methacrylate, and 30 g of N,N-diisopropylcarbodiimide were dissolved in dichloromethane by mass. Then, 3.0 g of 4-dimethylaminopyridine p-toluenesulfonate was added. The mixture was reacted at 30 °C for 20 h. After the reaction was completed, the mixture was rotary evaporated. The reaction product was dissolved in a mixture of diethyl ether and 2 mol / L hydrochloric acid. The mixture was then extracted twice with 2 mol / L hydrochloric acid. After that, it was extracted three times with 1 mol / L sodium carbonate solution. Finally, it was extracted once with saturated brine. The mixture was rotary evaporated at 50 °C for 0.5 h to obtain a transparent, viscous, yellow oily liquid, which is the aldehyde-containing functional monomer.

[0043] (2) Preparation of aldehyde-containing polymer materials: By mass, 8 mmol of butyl acrylate, 2 mmol of the aldehyde-containing functional monomer obtained in step (1), and 5 μmol of benzoyl peroxide were mixed in N,N-dimethylformamide and stirred evenly. The mixture was then degassed and deoxygenated by freezing for 40 min, heated to 60 °C, and reacted for 24 h. The resulting polymer solution was settled in a mixed solvent of methanol and water, centrifuged, and placed in a vacuum oven at 70 °C for 12 h. The aldehyde-containing polymer material was obtained. The 1H NMR spectrum of the aldehyde-containing polymer material is shown below. Figure 2 As shown, from Figure 2 The results show that the chemical shift of 10.05 ppm is attributed to the hydrogen in the aldehyde group of the polymer, the chemical shift of 1.34 ppm corresponds to the hydrogen in the methylene group of butyl acrylate, and the chemical shift of 5.50 ppm, which belongs to the carbon-carbon double bond in the monomer, has disappeared, proving that the design of the aldehyde-containing polymer was successful.

[0044] (3) Preparation of a room-temperature self-healing polymer film: 0.02 g of amino silica was dispersed in ethanol to prepare a solution, and 0.98 g of the aldehyde-containing polymer obtained in step (2) was dissolved in chloroform to prepare a solution. The two were mixed and vortexed to form a homogeneous solution. The solution was placed in a polytetrafluoroethylene mold to evaporate the solvent and form a film. After the solvent evaporated completely, the film was placed in a vacuum drying oven at a vacuum degree of 0.08 MPa for 24 h. A strong and tough composite material X3 capable of room-temperature repair was obtained. In this step, the mass content of amino silica was 2%.

[0045] Example 4

[0046] (1) Synthesis of aldehyde-containing monomers: 22.2 g of p-carboxybenzaldehyde, 33.2 g of hydroxyethyl methacrylate, and 30 g of N,N-diisopropylcarbodiimide were dissolved in dichloromethane by mass. Then, 3.0 g of 4-dimethylaminopyridine p-toluenesulfonate was added. The mixture was reacted at 30 °C for 20 h. After the reaction was completed, the product was dissolved by rotary evaporation. The product was then dissolved by adding a mixture of butyl acetate and 2 mol / L hydrochloric acid. The product was then extracted twice with 2 mol / L hydrochloric acid. After that, the product was extracted three times with 1 mol / L sodium carbonate solution. Finally, the product was extracted once with saturated brine. The product was then rotary evaporated at 50 °C for 0.5 h to obtain a transparent, viscous, yellow oily liquid, which is the aldehyde-containing functional monomer.

[0047] (2) Preparation of aldehyde-containing polymer material: By mass, 8 mmol of ethyl acrylate, 2 mmol of the aldehyde-containing functional monomer obtained in step (1), and 5 μmol of benzoyl peroxide were mixed in N,N-dimethylformamide and stirred evenly. The mixture was then degassed and deoxygenated by freezing for 40 min, heated to 60 °C, and reacted for 24 h. The resulting polymer solution was settled in a mixed solvent of methanol and water, centrifuged, and placed in a vacuum oven at 70 °C for 12 h. Aldehyde-containing polymer material X4 was obtained. In this step, the molar content of butyl acrylate was 80%.

[0048] (3) Preparation of a room-temperature self-healing polymer film: 0.05 g of amino silica was dispersed in ethanol to prepare a solution, and 0.95 g of the aldehyde-containing polymer obtained in step (2) was dissolved in chloroform to prepare a solution. The two were mixed and vortexed to form a homogeneous solution. The solution was placed in a polytetrafluoroethylene mold to evaporate the solvent and form a film. After the solvent evaporated completely, the film was placed in a vacuum drying oven at a vacuum degree of 0.08 MPa for 24 h. A strong and tough composite material X4 capable of room-temperature repair was obtained. In this step, the mass content of amino silica was 5%.

[0049] like Figure 3 As shown, with the increase of amino silica content, the fracture stress of X1 to X4 gradually increases, while the elongation at break gradually decreases. This is because with the increase of amino silica content, there are more dynamic cross-linking points of Schiff base inside the material, which increases the fracture stress and decreases the elongation at break. In addition, silica nanoparticles also play a toughening role, resulting in the improvement of the mechanical properties of polymer materials.

[0050] Example 5

[0051] (1) Synthesis of aldehyde-containing monomers: 22.2 g of p-carboxybenzaldehyde, 41.1 g of hydroxyethyl methacrylate, and 30 g of N,N-diisopropylcarbodiimide were dissolved in dichloromethane by mass. Then, 3.0 g of 4-dimethylaminopyridine p-toluenesulfonate was added. The mixture was reacted at 30 °C for 20 h. After the reaction was completed, the mixture was rotary evaporated. The reaction product was dissolved in a mixture of butyl acetate and 2 mol / L hydrochloric acid. The mixture was then extracted twice with 2 mol / L hydrochloric acid. After that, it was extracted three times with 1 mol / L sodium carbonate solution. Finally, it was extracted once with saturated brine. The mixture was rotary evaporated at 50 °C for 0.5 h to obtain a transparent, viscous, yellow oily liquid, which is the aldehyde-containing functional monomer.

[0052] (2) Preparation of aldehyde-containing polymer material: 9 mmol of ethyl acrylate, 1 mmol of the aldehyde-containing functional monomer obtained in step (1), and 5 μmol of azobisisobutyronitrile were mixed in N,N-dimethylformamide and stirred until homogeneous. The mixture was then degassed and deoxygenated by freezing for 40 min, heated to 60 °C, and reacted for 24 h. The resulting polymer solution was settled in a mixed solvent of methanol and water, centrifuged, and placed in a vacuum oven at 70 °C for 12 h. Aldehyde-containing polymer material X5 was obtained.

[0053] (3) Preparation of a room-temperature self-healing polymer film: 0.05 g of amino silica was dispersed in ethanol to prepare a solution, and 0.95 g of the aldehyde-containing polymer obtained in step (2) was dissolved in chloroform to prepare a solution. The two were mixed and vortexed to form a homogeneous solution. The solution was placed in a polytetrafluoroethylene mold to evaporate the solvent and form a film. After the solvent evaporated completely, the film was placed in a vacuum drying oven at a vacuum degree of 0.08 MPa for 24 h. A strong and tough composite material X5 capable of room-temperature repair was obtained. In this step, the mass content of amino silica was 5%.

[0054] like Figure 9 As shown, as the content of aldehyde monomers in the copolymer increases, the breaking stress of the polymer increases while the elongation at break decreases. This is because the benzene ring structure in the aldehyde monomers gives the material higher rigidity.

[0055] Comparative Example 1

[0056] (1) Synthesis of aldehyde-containing monomers: 22.2 g of p-carboxybenzaldehyde, 20.05 g of hydroxyethyl methacrylate, and 30 g of N,N-diisopropylcarbodiimide were dissolved in dichloromethane by mass. Then, 3.0 g of 4-dimethylaminopyridine p-toluenesulfonate was added. The mixture was reacted at 30 °C for 20 h. After the reaction was completed, the mixture was rotary evaporated. The reaction product was dissolved in a mixture of ethyl acetate and 2 mol / L hydrochloric acid. The mixture was then extracted twice with 2 mol / L hydrochloric acid. After that, it was extracted three times with 1 mol / L sodium carbonate solution. Finally, it was extracted once with saturated brine. The mixture was rotary evaporated at 50 °C for 0.5 h to obtain a transparent, viscous, yellow oily liquid, which is the aldehyde-containing functional monomer.

[0057] (2) Preparation of aldehyde-containing polymer material: By mass, 8 mmol of ethyl acrylate, 2 mmol of the aldehyde-containing functional monomer obtained in step (1), and 4 μmol of benzoyl peroxide were mixed in N,N-dimethylacetamide and stirred evenly. The mixture was then degassed and deoxygenated by freezing for 40 min, heated to 60 °C, and reacted for 24 h. The resulting polymer solution was settled in a mixed solvent of methanol and water, centrifuged, and placed in a vacuum oven at 70 °C for 12 h. The aldehyde-containing polymer material was obtained. In this step, the content of ethyl acrylate was 80%.

[0058] (3) 0.1 g of amino silica was dispersed in methanol to prepare a solution, and 0.9 g of the aldehyde-containing polymer obtained in step (2) was dissolved in chloroform to prepare a solution.

[0059] In this example, the mass content of amino silica is 10% (higher than the scope of this invention). Due to the introduction of excessive crosslinking sites into the system, the viscosity of the solution system rises rapidly and gels, making it impossible to obtain a homogeneous film. Figure 7 As shown.

[0060] Comparative Example 2

[0061] (1) Synthesis of aldehyde-containing monomers: 22.2 g of p-carboxybenzaldehyde, 20.05 g of hydroxyethyl methacrylate, and 30 g of N,N-diisopropylcarbodiimide were dissolved in dichloromethane by mass. Then, 3.0 g of 4-dimethylaminopyridine p-toluenesulfonate was added. The mixture was reacted at 30 °C for 20 h. After the reaction was completed, the mixture was rotary evaporated. The reaction product was dissolved in a mixture of ethyl acetate and 2 mol / L hydrochloric acid. The mixture was then extracted twice with 2 mol / L hydrochloric acid. After that, it was extracted three times with 1 mol / L sodium carbonate solution. Finally, it was extracted once with saturated brine. The mixture was rotary evaporated at 50 °C for 0.5 h to obtain a transparent, viscous, yellow oily liquid, which is the aldehyde-containing functional monomer.

[0062] (2) Preparation of aldehyde-containing polymer material: By mass, 8 mmol of ethyl acrylate, 2 mmol of the aldehyde-containing functional monomer obtained in step (1), and 0.05 μmol of benzoyl peroxide were mixed in N,N-dimethylformamide and stirred evenly. The mixture was then degassed and deoxygenated by freezing for 40 min, heated to 60 °C, and reacted for 24 h. The resulting polymer solution was settled in a mixed solvent of methanol and water, centrifuged, and placed in a vacuum oven at 70 °C for 12 h. The aldehyde-containing polymer material was obtained. In this step, the content of ethyl acrylate was 80%.

[0063] (3) Dissolve 1g of the obtained aldehyde-containing polymer in chloroform to prepare a solution without adding amino silica particles. Place the polymer solution in a polytetrafluoroethylene mold to evaporate the solvent and form a film. After the solvent has evaporated, place it in a vacuum drying oven at a vacuum degree of 0.08MPa for 24h to obtain the thin film Y2.

[0064] Because the system lacks crosslinking and toughening by amino silica particles, the resulting linear polymer exhibits very weak mechanical properties, with a maximum strength of 1.09 MPa. Figure 3 As shown.

[0065] Comparative Example 3

[0066] (1) Take 8 mmol of butyl acrylate and 4 μmol of benzoyl peroxide and mix them in N,N-dimethylformamide. Stir well, freeze to remove gas and oxygen for 40 min, heat to 60℃ and react for 24 h. The resulting polymer solution is settled in methanol, centrifuged and placed in a vacuum oven at 70℃ for 12 h to obtain polyethyl acrylate polymer.

[0067] (2) By mass, 0.005 g of amino silica was dispersed in ethanol to prepare a solution. 0.995 g of the polyethyl acrylate polymer obtained in the previous step was dissolved in chloroform to prepare a solution. The two were mixed and vortexed to form a homogeneous solution. The solution was placed in a polytetrafluoroethylene mold to evaporate the solvent and form a film. After the solvent had evaporated completely, the solution was placed in a vacuum drying oven at 0.08 MPa for 24 hours. The resulting material was a colloid rather than a thin film.

[0068] Because no aldehyde-containing polymers are added during the preparation process, the linear polymer lacks sufficient hard segments to provide mechanical strength. Therefore, pure polybutyl acrylate behaves more like a colloid and its mechanical strength cannot be tested. Figure 8 As shown.

[0069] Comparative Example 4

[0070] (1) Synthesis of aldehyde-containing monomers: 22.2 g of p-carboxybenzaldehyde, 20.05 g of hydroxyethyl methacrylate, and 30 g of N,N-diisopropylcarbodiimide were dissolved in dichloromethane by mass. Then, 3.0 g of 4-dimethylaminopyridine p-toluenesulfonate was added. The mixture was reacted at 30 °C for 20 h. After the reaction was completed, the mixture was rotary evaporated. The reaction product was dissolved in a mixture of ethyl acetate and 2 mol / L hydrochloric acid. The mixture was then extracted twice with 2 mol / L hydrochloric acid. After that, it was extracted three times with 1 mol / L sodium carbonate solution. Finally, it was extracted once with saturated brine. The mixture was rotary evaporated at 50 °C for 0.5 h to obtain a transparent, viscous, yellow oily liquid, which is the aldehyde-containing functional monomer.

[0071] (2) Preparation of aldehyde-containing polymer materials: 5 mmol of ethyl acrylate, 5 mmol of the aldehyde-containing functional monomer obtained in step (1), and 5 μmol of azobisisobutyronitrile were mixed in DMAC and stirred evenly. The mixture was then frozen to remove gas and oxygen for 40 min, heated to 60 °C, and reacted for 24 h. The resulting polymer solution was then settled in methanol, centrifuged, and placed in a vacuum oven at 70 °C for 12 h. The aldehyde-containing polymer materials were obtained.

[0072] (3) Preparation of a room-temperature self-healing polymer film: 0.005 g of amino silica was dispersed in ethanol to prepare a solution. 0.995 g of the aldehyde-containing polymer obtained in step (2) was dissolved in chloroform to prepare a solution. The two were mixed and vortexed to form a homogeneous solution. The solution was placed in a polytetrafluoroethylene mold to evaporate the solvent and form a film. After the solvent had evaporated, the film was placed in a vacuum drying oven at 0.08 MPa for 24 h. The polymer film Y1 was obtained. In this step, the content of amino silica was 0.5%.

[0073] In this example, due to insufficient ethyl acrylate content in step 2) (the molar ratio with the aldehyde-containing monomer is 1:1), and excessive aldehyde-containing monomer, the system contains a large number of benzene rings, which restricts the mobility of chain segments in the material, preventing the material from being repaired at room temperature. The mechanical property curves of the composite material Y1 obtained in this example are shown below. Figure 5 .from Figure 5 It can be seen that the composite material has a strength of up to 8.7 MPa, but its elongation at break is only 48%, indicating poor mechanical properties.

[0074] Test Example 1: Room Temperature Repair Performance and Mechanical Properties Test

[0075] In the self-healing test, the room-temperature self-healing, tough composite film obtained in Example 2 was cut in half with a blade, and the cut surfaces were gently put together, allowing the film to heal at room temperature for a certain period of time. The mechanical and repair properties of the pre-cut dumbbell-shaped strips were tested using a static testing system from ZWICKARMATUREN GMBH (Germany), with a tensile rate of 100 mm / min to ensure performance stability. To ensure the accuracy of the experimental data, each sample was stretched three times and the average value was calculated.

[0076] Figure 6 This refers to the room-temperature self-healing, tough composite film obtained in Example 2. From... Figure 6 As can be seen, after the film is cut, the cut surfaces are aligned and repaired at room temperature for 24 hours, the material can be stretched without breaking.

[0077] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for preparing a room-temperature self-healing, tough composite material film, characterized in that, The steps are as follows: 1) A functional monomer containing an aldehyde group is prepared using carboxybenzaldehyde monomers, 4-dimethylaminopyridine p-toluenesulfonate and hydroxyethyl methacrylate; wherein the molar ratio of the carboxybenzaldehyde monomers to 4-dimethylaminopyridine p-toluenesulfonate is 1:1 and the mass ratio of the carboxybenzaldehyde monomers to hydroxyethyl methacrylate is 1:1 to 1:

2. 2) The aldehyde-containing functional monomers and acrylic monomers from step 1) are combined in a molar ratio of 1:9-2:8 to synthesize aldehyde-containing polymers; 3) Mix the amino nanoparticles and the aldehyde-containing polymer obtained in step 2) to form a film, wherein the mass content of the amino nanoparticles is 0.1%-5%.

2. The method for preparing a room-temperature self-healing, tough composite film according to claim 1, characterized in that, Step 1) The carboxybenzaldehyde monomers include one or more of 2-carboxybenzaldehyde, 3-carboxybenzaldehyde, and 4-carboxybenzaldehyde.

3. The method for preparing a room-temperature self-healing, tough composite film according to claim 1, characterized in that, The mass content of the amino nanoparticles in step 3) is 0.2% to 5%.

4. The method for preparing a room-temperature self-healing, tough composite film according to claim 1, characterized in that, Step 3) The amino nanoparticles mentioned are one or more of amino ceramic particles, amino silica, amino iron tetroxide, amino carbon dots, and amino carbon nanotubes.

5. The method for preparing a room-temperature self-healing, tough composite film according to claim 1, characterized in that, The acrylic monomers mentioned in step 2) include one or more of methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, n-hexyl acrylate, and n-octyl acrylate.

6. The method for preparing a room-temperature self-healing, tough composite film according to claim 1, characterized in that, Step 1) involves dissolving carboxybenzaldehyde, 4-dimethylaminopyridine p-toluenesulfonate, and a dehydrating agent in a first solvent, then adding a hydroxyethyl methacrylate solution dropwise to the above solution to react and obtain the product. The product is then extracted by rotary evaporation, followed by extraction with a second, third, and fourth solvent, and then by rotary evaporation to obtain a functional monomer containing an aldehyde group. The reaction temperature is 20–100ºC, the reaction time is 10–24 h, the rotary evaporation temperature is 25–55ºC, and the rotary evaporation time is 0.5–1 h. Step 2) involves mixing the aldehyde-containing functional monomer and the initiator, adding them to the fifth solvent, stirring until homogeneous, then purging with an inert gas to remove oxygen, heating to react, and adding the resulting polymer solution to the sixth solvent. The mixture is then allowed to settle, centrifuged, and dried to obtain the aldehyde-containing polymer. The deoxygenation time is 30–60 min, the heating temperature is 50–100°C, the reaction time is 1–48 h, the drying temperature is 40–90°C, and the drying time is 10–36 h. Step 3) involves dispersing amino nanoparticles in the seventh solvent to prepare a nanoparticle dispersion, dissolving the aldehyde-containing polymer in the eighth solvent to prepare an aldehyde-containing polymer solution, mixing the nanoparticle dispersion and the aldehyde-containing polymer solution, and then placing the mixture in a mold to form a film, thereby obtaining a strong and tough composite film that can self-heal at room temperature.

7. The method for preparing a room-temperature self-healing, tough composite film according to claim 6, characterized in that, The dehydrating agent in step 1) comprises dicyclohexylcarbodiimide, N,N′-diisopropylcarbodiimide, and 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride; the first solvent in step 1) is one or more of chloroform, dichloromethane, tetrahydrofuran, N,N-dimethylformamide, and N,N-dimethylacetamide; the second solvent is one or more of diethyl ether, ethyl acetate, butyl acetate, and hydrochloric acid.

8. The method for preparing a room-temperature self-healing, tough composite film according to claim 6, characterized in that, Step 2) The initiator includes one or more of azobisisobutyronitrile, azobisisoheptanenitrile, benzoyl peroxide, lauroyl peroxide, and diisopropyl peroxide dicarbonate; the molar ratio of acrylic monomer to initiator is 200:1-500:1; the fifth solvent includes one or more of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, toluene, xylene, and petroleum ether; the sixth solvent includes one or more of deionized water, methanol, and ethanol.

9. The method for preparing a room-temperature self-healing, tough composite material film according to claim 6, characterized in that, The seventh solvent mentioned in step 3) includes one or more of methanol, ethanol, and deionized water; the eighth solvent includes one or more of tetrahydrofuran, N,N-dimethylformamide, and chloroform.

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