WO2021098614A1

WO2021098614A1 - Nanocomposite material and preparation method thereof

Info

Publication number: WO2021098614A1
Application number: PCT/CN2020/128852
Authority: WO
Inventors: 于淑会; 吴旭东; 孙蓉
Original assignee: 中国科学院深圳先进技术研究院
Priority date: 2019-11-22
Filing date: 2020-11-13
Publication date: 2021-05-27
Also published as: CN110698706A; CN110698706B

Abstract

The invention relates to a nanocomposite material and a preparation method thereof. Specifically, a preparation method of a nanocomposite material with self-healing properties is disclosed. The preparation method comprises the following steps: (1) reacting a polymer polyol and a polyisocyanate to prepare a polyurethane prepolymer with both ends terminated with -NCO; (2) adding self-healing functional molecules to the polyurethane prepolymer with both ends terminated with -NCO, and heating and reacting to obtain a polyurethane matrix with self-healing properties; (3) adding a filler to the polyurethane matrix with self-healing properties to prepare a nanocomposite material mixture; and (4) removing the solution to obtain a composite material. The nanocomposite material of the present invention can perform self-healing upon heating. The recovery of the dielectric and mechanical properties of the nanocomposite material after self-healing are excellent.

Description

Nano composite material and preparation method thereof

Technical field

The invention belongs to the technical field of composite materials, and relates to a nano composite material, a preparation method thereof, and a self-repair method.

Background technique

With the development of electronic information technology, especially in recent years, the rapid development of wearable electronics, smart phones, ultra-thin computers, unmanned driving, Internet of Things technology and 5G communication technology has led to the miniaturization and thinning of electronic systems. , Multi-function, high performance and other aspects put forward higher and higher requirements. Insulating dielectric material is an important material for electronic packaging technology. The higher the dielectric constant, the more advantageous the miniaturization of electronic products. In high-frequency and high-speed applications, in order to reduce the loss of the signal transmission process, it is required to have low dielectric loss. Generally, the dielectric material that functions as a capacitor is generally discretely mounted on the package substrate. The distance between the capacitor and the chip is large, resulting in large parasitic losses.

Polymer-based flexible media have been widely used in modern technologies such as implantable sensors, wearable electronic devices, and cardiac pacemakers due to their characteristics of insulation, energy storage, and high power density. By choosing ceramics or conductive materials with specific dimensions, shapes and physical properties as fillers, the polymer can be made to obtain high dielectric properties.

The concept of self-repair was first proposed by the U.S. military in the mid-1980s. The purpose of self-repair is to make polymer materials have the ability to prevent cracks from propagating in the initial stage of internal crack formation. By giving electronic equipment materials the ability to self-repair, Repair breaks and cracks caused by mechanical or electrical damage, provide reliability and stability for materials and devices, and extend the service life of materials. Early self-healing research focused on composite materials based on epoxy resin and epoxy vinyl resin. As a rigid or brittle material, composite materials usually have micro-cracks that appear instantaneously under external impact, and the crack growth rate is faster, the degree of expansion is greater, and the time required for damage is relatively short. Crack repair is an effective method to keep materials and devices in normal operation.

In the past two decades, self-healing polymers based on various methods such as metal coordination interactions, ionic bonds, and Diels-Alder reactions have been developed. The previous exploration mainly focused on the recovery of mechanical properties. For example, [Yanagisawa et al., Science 359, 72–76 (2018)] reported that a low-molecular-weight polymer with high mechanical strength and easy repair is cross-linked through three dense hydrogen bond arrays, and the maximum mechanical strength recovery is 100%. In recent years, the recovery of electrical conductivity of self-healing materials has attracted widespread attention. [Adv. Mater. 2013, 25, 4186-4191] reported a self-healing translucent conductive polymer film that can restore 97% of the surface conductivity when heated at 110 ℃. In recent years, researchers have studied the dielectrics of self-healing materials. [NATURE CHEMISTRY | VOL 8 | JUNE 2016] reported a self-healing poly(dimethylsiloxane) elastomer network. Through complex cross-linking, the material obtained high dielectric strength and high tensile properties, but its The maximum breaking stress is only 0.55 MPa. [ACS Macro Lett. 2016, 5, 1196−1200] reported a dielectric silicon elastomer actuator. The actuator is composed of an ionically cross-linked interpenetrating polymer network. The material has a certain degree of self-repair after electrical breakdown. Ability, but the self-repair efficiency is less than 50%.

technical problem

Therefore, flexible electronic devices require clever structural design of materials to have multiple excellent performance and high self-repair efficiency.

Technical solutions

In order to solve the above-mentioned problems, the present invention provides a high-dielectric insulating adhesive film material that can be used for semiconductor packaging and suitable for the additive method or semi-additive method to prepare packaging substrates, characterized in that the insulating adhesive film material has high dielectric properties. The electric constant and low dielectric loss exist in the form of thin film at the same time. The capacitor can be embedded in the package substrate as needed and processed at a position close to the chip, and the capacitance value of the capacitor can be designed according to the electrode area. The capacitance value. It can not only improve the mechanical properties of the polymer, but also have certain mechanical and dielectric repair capabilities, and the performance of the materials before and after the repair is not much different.

The purpose of the present invention is to provide a nano composite material and its preparation method and self-repair method.

The present invention adopts the following technical solutions:

In the first aspect, the present invention provides a nanocomposite material, the nanocomposite material includes a filler and a self-healing polymer matrix, the filler is uniformly dispersed in the self-healing polymer matrix,

Wherein, the self-repairing polymer matrix is formed by connecting a polyurethane prepolymer and a self-repairing functional molecule, the polyurethane prepolymer is formed by the reaction of a polymer polyol and a polyisocyanate, and the self-repairing functional molecule adopts Diels-Alder reaction chemistry. The response is obtained.

In the technical scheme of the present invention, the polyurethane prepolymer is only obtained by the reaction of a polymer polyol and a polyisocyanate. Preferably, the reaction temperature is 60-95°C, preferably 80-85°C.

In the technical scheme of the present invention, the polymer polyol is selected from hydroxyl-terminated polymers, hydroxyl-terminated polytetrahydrofuran, hydroxyl-terminated polyethylene glycol, hydroxyl-terminated polypropylene glycol, hydroxyl-terminated polytetrahydrofuran ether glycol, hydroxyl-terminated polycarbonate One or more of hexylene glycol ester or hydroxyl-terminated polybutylene adipate.

In the technical scheme of the present invention, the polyvalent isocyanate is selected from one or more combinations of isophorone diisocyanate, toluene 2,4-diisocyanate or diphenylmethane diisocyanate.

In the technical scheme of the present invention, the filler is inorganic ceramic filler or conductive material.

In the technical scheme of the present invention, the inorganic ceramic filler is selected from barium titanate, strontium titanate, barium strontium titanate, lead zirconate titanate, silicon carbide, boron nitride, One or a combination of at least two of aluminum oxide, titanium dioxide, silicon dioxide, zinc oxide, or zinc sulfide.

In the technical scheme of the present invention, the conductive filler is selected from one or a combination of at least two of carbon powder, graphene, acetylene black, and polyaniline.

In the technical scheme of the present invention, the self-repairing functional molecule is obtained by the reaction of bismaleimide and furfuryl alcohol, and preferably, the reaction temperature is 50-90°C.

In the technical scheme of the present invention, no hydroxy acrylate, polymerization inhibitor, catalyst and other components are added during the preparation process of the nanocomposite material, and the polymerization inhibitor includes hydroquinone, p-hydroxyanisole, One or more of p-methoxyphenol, o-methylhydroquinone, 2,6-di-tert-butyl-4-methylphenol; the catalyst includes triphenylbismuth, tris(ethoxy One or more of phenyl)bismuth, iron acetylacetonate, dibutyltin dilaurate, and triphenyltin chloride.

In the technical solution of the present invention, the molar ratio between the polyurethane prepolymer and the self-healing functional molecule is 1:0.1-1:10, preferably 1:0.5-1:1.5, more preferably 1:1.

In the technical scheme of the present invention, the mass relationship between the self-healing polymer matrix and the filler is 1:0.01-1:0.3.

In the technical scheme of the present invention, the ratio of the number of moles of hydroxyl groups in the polymer polyol to the number of moles of cyanate in the polyisocyanate is 1:2.

In the second aspect, the present invention provides a method for preparing a nanocomposite material with self-healing properties, including the following steps:

(1) The high polymer polyol and the polyisocyanate are reacted to prepare a polyurethane prepolymer with both ends-NCO terminated;

(2) Adding self-healing functional molecules to the polyurethane prepolymer with NCO-terminated ends to obtain a polyurethane matrix with repairing properties;

(3) Add fillers to the polyurethane matrix with repair properties to prepare a nanocomposite material mixture;

(4) Remove the solution to obtain a composite material.

The reaction temperature in step (1) is 60-95°C, preferably 80-85°C.

The reaction temperature in step (2) is 60-95°C, preferably 80-85°C.

In the technical scheme of the present invention, the polymer polyol is selected from one of polytetrahydrofuran, polyethylene glycol, polypropylene glycol, polytetrahydrofuran ether glycol, polyhexylene carbonate or polybutylene adipate. Kind or more.

In the technical scheme of the present invention, steps 1)-4) are all reacted under the protection of an inert atmosphere.

In the preparation method of the present invention, no hydroxy acrylate, polymerization inhibitor, catalyst and other components are added during the preparation process of the nanocomposite material, and the polymerization inhibitor includes hydroquinone, p-hydroxyanisole, One or more of p-methoxyphenol, o-methylhydroquinone, 2,6-di-tert-butyl-4-methylphenol; the catalyst includes triphenylbismuth, tris(ethoxy One or more of phenyl)bismuth, iron acetylacetonate, dibutyltin dilaurate, and triphenyltin chloride.

In the technical scheme of the present invention, the filler is selected from inorganic ceramic filler or conductive material.

Another aspect of the present invention provides a method for repairing the nanocomposite material of the present invention, which includes the following steps:

1) Assemble the sections to be repaired;

2) Heating at 120-150°C to partially open the Diels-Alder loop, and then heating at 55-75°C to partially close the Diels-Alder loop to complete the repair of the material.

The heating time at 120-150°C to partially open the Diels-Alder ring is 10-100 minutes, and the time to partially close the Diels-Alder ring is 12-36 hours.

Beneficial effect

(1) The composite material provided by the present invention contains repair molecules, which break after being stimulated by heat, and can be regenerated after a certain heat treatment, so that the composite material can achieve the purpose of self-repair;

(2) Adding inorganic nano-fillers to composite materials can effectively improve the mechanical properties and dielectric properties of the materials;

(3) The composite material provided by the present invention can be self-repaired under certain conditions of heat treatment, and the repair efficiency after mechanical damage can reach 60-95%.

As a rigid or brittle material, composite materials usually have micro-cracks that appear instantaneously under external impact, and the crack growth rate is faster, the degree of expansion is greater, and the time required for damage is relatively short; self-repairing technology is used to internally micro-cracks the composite material. Crack repair is an effective method to keep materials and devices in normal operation.

Description of the drawings

Through the following description with reference to the accompanying drawings, in the product of the embodiment of the present invention, the nanoparticles can be uniformly dispersed in the polymer, and the resulting product is flexible.

Figure 1 is a cross-sectional view of the product obtained in Example 1;

Figure 2 shows the dielectric properties of the product obtained in Example 1 before and after being cut. It can be seen that after the product is repaired, the dielectric constant and dielectric loss remain the same as before the damage; where a) is the initial dielectric constant with frequency The change curve of b) is the change curve of the loss factor with frequency in the initial state, c) is the change curve of the dielectric constant with frequency in the repaired state after cutting off, d) is the change curve of the loss factor with frequency in the repaired state after cutting off .

Figure 3 shows the mechanical properties of the product obtained in Example 1 before and after being cut. It can be seen that after the product is repaired, the stress and strain can be greatly restored to the initial level (a) is the stress-strain curve of the polymer without filler, (b) is the polymer nanocomposite with a filler mass fraction of 0.5% The stress-strain curve, (c) is the stress-strain curve of the polymer nanocomposite with a filler mass fraction of 1%, (d) is the stress-strain curve of the polymer nanocomposite with a filler mass fraction of 3%, and (e) is The filler mass fraction is the stress-strain curve of 5% polymer nanocomposite.

(F) is a photo of mechanical stretching of the product obtained in Example 1 after being cut and self-repaired. The left picture is the undamaged mechanical stretching picture of the product, and the right picture is the mechanical stretching picture of the damaged and repaired product. It can be seen that , The stress and strain of the material have been greatly restored, and the repair efficiency is calculated by the stress, and the repair efficiency is 60%-80%.

Embodiments of the present invention

In order to make the above objectives, features and advantages of the present invention more obvious and understandable, the specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, but they should not be understood as limiting the scope of implementation of the present invention.

Example 1:

Step 1: Under the protection of an inert atmosphere, mix the ^{hydroxyl-terminated polytetrahydrofuran (4.0 g) with a molecular weight of 2000g mol -1} and N,N-dimethylformamide (DMF) (15g) thoroughly, and add the mixed solution at room temperature In a three-necked flask.

Step 2: Under the protection of an inert atmosphere, combine diphenylmethane diisocyanate (MDI) (1.050 g) and DMF (10 g) Mix at room temperature.

Step 3: Under the protection of an inert atmosphere, add the mixture of step 2 to the mixture of step 1 through a normal pressure funnel. React at 80°C for 3h under a nitrogen atmosphere.

Step 4: Under the protection of an inert atmosphere, combine 0.75 g bismaleimide (BMI) and 0.40 g Furfuryl alcohol (FA) was mixed with 9.6g DMF and heated in an oven at 70°C for 3 hours to obtain the repaired part.

Step 5: Add the repaired part as a chain extender to the product of step 3 under the protection of an inert atmosphere, and heat it at 80° C. under nitrogen for 3 hours to obtain a polyurethane containing the repaired part.

Step 6: Under the protection of an inert atmosphere, add titanium dioxide nano-filler to the product of Step 5 to prepare nanocomposites with a titanium dioxide content of 0, 0.5 wt%, 1 wt%, 3 wt%, and 5 wt% of the polyurethane content, respectively.

Step 7: Under the protection of an inert atmosphere, pour an appropriate amount of the mixed solution into a polytetrafluoroethylene mold, and form the composite material into a film by evaporation of the solution.

Step 8: Cut the film into two pieces with a sharp blade, touch the two parts together, then heat at 120-150℃ for 0.5-1h to open the Diels-Alder part, and then heat at 55-75℃ for 24h to make Diels-Alder partially closed the loop to complete the restoration of the material. Repair efficiency is defined as the ratio of the fracture stress after repair to the mechanical tensile stress that was originally damaged

Step 9: Test the dielectric properties and mechanical properties of the cut polymer film and the repaired polymer film. The results obtained are shown in Figure 2 and Figure 3. It can be seen that after the product is repaired, the dielectric constant and dielectric loss remain the same as before the damage; it can be seen that the stress and strain of the material have been restored to a greater extent. To calculate the repair efficiency and get 60%-80% repair efficiency

Step 10: Use a broadband dielectric impedance analyzer to measure the dielectric properties of the nanocomposite in the frequency range of 100Hz-10MHz.

Step 11: The stress-strain curve is tested on a universal testing machine with a tensile speed of 50mm min ^-1 .

Example 2:

Step 1: Under the protection of an inert atmosphere, mix the ^{hydroxyl-terminated polytetrahydrofuran (2.0 g) with a molecular weight of 2000g mol -1} and N,N-dimethylformamide (DMF) (7.5g) thoroughly, and mix the mixed solution at room temperature Add to a three-necked flask.

Step 2: Under the protection of an inert atmosphere, combine diphenylmethane diisocyanate (MDI) (0.500 g) and DMF (5.0 g) Mix at room temperature.

Step 3: Under the protection of an inert atmosphere, add the mixture of step 2 to the mixture of step 1 through a normal pressure funnel. React at 85°C for 2h under a nitrogen atmosphere.

Step 4: Under the protection of an inert atmosphere, combine 0.375 g bismaleimide (BMI) and 0.20 g Furfuryl alcohol (FA) was mixed with 4.8g DMF and heated in an oven at 70°C for 3 hours to obtain the repaired part.

Step 5: Add the repaired part as a chain extender to the product of step 3 under the protection of an inert atmosphere, and heat at 85°C under nitrogen for 2 hours to obtain a polyurethane containing the repaired part.

Step 6: Under the protection of an inert atmosphere, add barium titanate nano fillers to the product of Step 5 to prepare nanocomposites with a titanium dioxide content of 0, 0.5 wt%, 1 wt%, 3 wt%, and 5 wt% of the polyurethane content, respectively.

Step 8: Cut the film into two pieces with a sharp blade, touch the two parts together, then heat at 120-150℃ for 0.5-1h to open the Diels-Alder part, and then heat at 55-75℃ for 24h to make Diels-Alder partially closed the loop to complete the restoration of the material.

Step 9: Test the dielectric properties and mechanical properties of the repaired polymer film.

The above-mentioned embodiments only describe the best solution of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, those of ordinary skill in the art have made various contributions to the technical solutions of the present invention. These improvements should fall within the protection scope determined by the claims of the present invention.

Claims

A preparation method of a self-healing nanocomposite material, including the following steps:

(1) The high polymer polyol and the polyisocyanate are reacted to prepare a polyurethane prepolymer with both ends-NCO terminated;

(2) Adding self-healing functional molecules to the polyurethane prepolymer with NCO-terminated ends, heating reaction to obtain a polyurethane matrix with repairing properties;

(3) Add fillers to the polyurethane matrix with repair properties to prepare a nanocomposite material mixture;

(4) Removal of solution to obtain composite material;

Preferably, the reaction temperature in step (1) is 60-95°C, more preferably 80-85°C;

Preferably, the reaction temperature in step (2) is 60-95°C, more preferably 80-85°C.
The preparation method according to claim 1, wherein the polymer polyol is selected from hydroxyl-terminated polymers, and the hydroxyl-terminated polymers are selected from polytetrahydrofuran, hydroxyl-terminated polyethylene glycol, hydroxyl-terminated polypropylene glycol, hydroxyl-terminated poly One or more of tetrahydrofuran ether glycol, hydroxyl-terminated polyhexylene carbonate or hydroxyl-terminated polybutylene adipate;

The polyvalent isocyanate is selected from one or more combinations of isophorone diisocyanate, toluene 2,4-diisocyanate or diphenylmethane diisocyanate.
The preparation method according to claim 1, wherein the filler is an inorganic ceramic filler or a conductive filler;

Preferably, the inorganic ceramic filler is selected from barium titanate, strontium titanate, barium strontium titanate, lead zirconate titanate, silicon carbide, boron nitride, aluminum oxide, titanium dioxide, silicon dioxide, zinc oxide or zinc sulfide One or a combination of at least two;

Preferably, the conductive filler is selected from one or a combination of at least two of carbon powder, graphene, acetylene black, and polyaniline.
The preparation method according to claim 1, wherein the self-repairing functional molecule is obtained by reacting bismaleimide and furfuryl alcohol, and preferably, the reaction temperature is 50-90°C.
The preparation method according to claim 1, wherein the hydroxy acrylate, polymerization inhibitor and catalyst are not added during the preparation of the nanocomposite material.
The preparation method according to claim 1, wherein the mass relationship between the self-healing polymer matrix and the filler is 1:0.01-1:0.3.
The preparation method according to claim 1, wherein the molar ratio between the polyurethane prepolymer and the self-healing functional molecule is 1:0.1-1:10, preferably 1:0.5-1:1.5, more preferably 1: 1.
The preparation method according to claim 1, wherein the ratio of the number of moles of hydroxyl groups in the polymer polyol to the number of moles of cyanate in the polyisocyanate is 1:2.
A nanocomposite material with self-healing properties prepared according to the preparation method of any one of claims 1-8.
A nano composite material, the nano composite material comprises a filler and a self-healing polymer matrix, and the filler is uniformly dispersed in the self-healing polymer matrix,

Wherein, the self-healing polymer matrix is formed by connecting a polyurethane prepolymer and a self-healing functional molecule, the polyurethane prepolymer is formed by the reaction of a polymer polyol and a polyisocyanate, and the self-healing functional molecule adopts Diels-Alder reaction chemistry Response obtained

Preferably, the polymer polyol is selected from hydroxyl-terminated polymers, polytetrahydrofuran, polyethylene glycol, polypropylene glycol, polytetrahydrofuran ether glycol, polyhexylene carbonate or polybutylene adipate One or more; polyisocyanate is selected from one or more combinations of isophorone diisocyanate, toluene 2,4-diisocyanate or diphenylmethane diisocyanate; said filler is inorganic ceramic filler or Conductive filler; self-healing functional molecules are obtained by the reaction of bismaleimide and furfuryl alcohol.