CN112266611A

CN112266611A - Functionalized polyimide composite microsphere and preparation method thereof

Info

Publication number: CN112266611A
Application number: CN202011094375.0A
Authority: CN
Inventors: 张献; 张乾; 丁欣; 张萍; 郑康; 田兴友
Original assignee: Hefei Institutes of Physical Science of CAS
Current assignee: Hefei Institutes of Physical Science of CAS
Priority date: 2020-10-14
Filing date: 2020-10-14
Publication date: 2021-01-26
Anticipated expiration: 2040-10-14
Also published as: CN112266611B

Abstract

The invention discloses a functionalized polyimide composite microsphere and a preparation method thereof, wherein the preparation method comprises the steps of preparing polyamide acid microspheres, pretreating the polyamide acid microspheres, functionalizing the polyamide acid microspheres and preparing the functionalized polyimide microspheres; the method utilizes the advantages that the functionalized polyamide acid microsphere as a precursor of polyimide has more surface active groups and is easy to carry out surface modification, and hydrogen bonds and electrostatic adsorption force are used as binding energy, so that the functional materials such as heat-conducting filler, conductive filler, photocatalytic filler and the like are coated on the surface of the polyamide acid microsphere, and finally the functionalized polyamide microsphere is successfully prepared through thermal imidization. The preparation method designed by the invention can realize the coating of the polyimide microspheres by various functional materials, widens the application field of the polyimide composite microspheres, and has the advantages of universality, simple process route, low cost and easy mass production.

Description

Functionalized polyimide composite microsphere and preparation method thereof

Technical Field

The invention belongs to the technical field of electronic packaging materials, and particularly relates to a functionalized polyimide composite microsphere and a preparation method thereof.

Background

Polyimide is widely applied to the fields of aviation, microelectronics, liquid crystal display and the like due to excellent high and low temperature resistance, mechanical property, chemical stability, good dielectric property and the like. However, with the rapid development of downstream applications, polyimides have failed to meet specific performance requirements in industrial applications, such as electrical conductivity, thermal conductivity, electromagnetic shielding properties, and the like. The introduction of functional particles in a polyimide matrix is a common strategy for achieving functionalization. Meanwhile, in order to improve efficiency, designing a specific microstructure has become a hot spot of interest in recent years. The functionalized polyimide microspheres gradually attract attention due to the characteristics of convenience and functional diversity of use and the like.

Because the surfaces of the thermosetting polyimide microspheres are mostly imide groups and have no active groups, the special structure enables the polyimide microspheres to have higher rigidity and excellent chemical stability, so that certain difficulty is brought to surface modification of the polyimide microspheres, few relevant reports are brought to the surface modification of the thermosetting polyimide microspheres, and the thermosetting polyimide microspheres are difficult to coat by heat conduction materials, conductive materials, photocatalytic materials and the like. In addition, most of the polymer microspheres are modified in the previous research aiming at coating of a certain functional material, and the method has no universality. Therefore, a method for simply and effectively preparing the polyimide composite microspheres coated with the functional materials, which has universality and can be applied to various functional materials, is urgently needed.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provides a functionalized polyimide composite microsphere.

The invention aims to solve another technical problem and provides a preparation method of the functionalized polyimide composite microsphere for overcoming the defect that the polyimide in the prior art is difficult to modify.

In order to solve the technical problem, the technical scheme is that the functionalized polyimide composite microsphere is characterized in that the particle size of the functionalized polyimide composite microsphere is 0.5-10 mu m, the functionalized polyimide composite microsphere is formed by compounding a polyimide microsphere and a functional material according to the mass ratio of 100 (1-40), and the functional material is uniformly coated on the surface of the polyimide microsphere.

As a further improvement of the functionalized polyimide composite microsphere:

preferably, the functional material is one or a combination of two or more of graphene oxide, silicon dioxide, titanium dioxide, aluminum oxide, ferroferric oxide, boron nitride, graphene nanosheets and nano silver.

Preferably, the bonding force between the functional material and the polyimide microspheres is electrostatic adsorption force and hydrogen bonding.

In order to solve another technical problem of the invention, the technical scheme is a preparation method of the functionalized polyimide composite microsphere, which comprises the following steps:

s1, preparing polyamide acid microspheres: mixing an organic solvent and polyamic acid according to the mass ratio of (2-12) to 1 to obtain a mixed solution, stirring the mixed solution at 20-50 ℃ for 1-3h, then transferring the mixed solution into a constant temperature and humidity box with the humidity of 80-98% and the temperature of 25-50 ℃ for reaction for 8-24h, collecting a product, centrifugally washing the product by deionized water, and drying to obtain polyamic acid microspheres;

s2, pretreatment of polyamide acid microspheres: adding a water-soluble polymer into water to prepare a water-soluble polymer solution with the concentration of 0.01-0.06g/ml, adding 100 parts by mass of the polyamic acid microspheres prepared in the step S1 into the water-soluble polymer solution according to the addition mass ratio of 1 (100-200), performing ultrasonic dispersion to completely soak the microspheres, stirring for 0.5-1h, and performing centrifugal separation to obtain modified polyamic acid microspheres;

s3, functionalization of polyamide acid microspheres: weighing 1-40 parts by mass of functional material, adding the functional material into an aqueous solution with the pH value of 3-7, uniformly stirring, adding the modified polyamic acid microspheres prepared in the step S2, mixing, stirring for 5-30min, centrifugally washing with deionized water, and drying to obtain the functionalized polyamic acid composite microspheres;

s4, preparing functional polyimide microspheres: and (4) drying the functionalized polyamic acid composite microsphere prepared in the step (S3) at the temperature of 50-90 ℃ for 2-4h, raising the temperature to 220 ℃ at the rate of 1-10 ℃/min, preserving the heat for 1-3h, raising the temperature to 300 ℃ at the rate of 1-10 ℃/min, and preserving the heat for 1-2h to obtain the functionalized polyimide composite microsphere.

As a further improvement of the preparation method of the functionalized polyimide composite microsphere:

preferably, the organic solvent in step S1 is one of N, N-dimethylformamide, N-dimethylacetamide, cyclohexane and chloroform.

Preferably, the water-soluble polymer in step S2 is one of polyvinylpyrrolidone, polyvinyl alcohol, polyurethane, polyethylene glycol, and dopamine hydrochloride.

Compared with the prior art, the invention has the beneficial effects that:

(1) the invention solves the problems that the surface active group of thermosetting polyimide is few and the surface modification and the functional coating are difficult to carry out, utilizes the characteristic that the surface of a polyimide precursor, namely polyamic acid is easy to modify, realizes the coating of the polyamic acid microsphere by a functional material by modifying the polyamic acid microsphere, further realizes the coating of the polyimide by the functional material by a thermal imidization process, and provides the preparation method of the polyimide microsphere coated by the functional material.

(2) According to the invention, by regulating the concentration and the pH value of the water-soluble polymer solution of the polyamic acid microsphere, multiple binding forces such as hydrogen bonds, electrostatic adsorption force and the like exist between the polyamic acid microsphere and the functional material, and the coating of the functional material on polyimide is realized.

(3) The preparation method of the functionalized polyimide composite microsphere is simple and easy to implement, low in cost, environment-friendly, reliable and universal.

Drawings

Fig. 1 is a Scanning Electron Microscope (SEM) picture of a graphene oxide coated polyimide microsphere;

FIG. 2 is a Scanning Electron Microscope (SEM) picture of an alumina-coated polyimide microsphere;

FIG. 3 is a Scanning Electron Microscope (SEM) picture of a 30 wt% titanium dioxide coated polyimide microsphere;

FIG. 4 is a Scanning Electron Microscope (SEM) picture of a 15 wt% titanium dioxide coated polyimide microsphere;

FIG. 5 is a Scanning Electron Microscope (SEM) picture of 20 wt% titanium dioxide coated polyimide microspheres;

FIG. 6 is a graph comparing the degradation curve and the degradation effect of photocatalytic degradation of rhodamine B by titanium dioxide coated polyimide microspheres.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments, and all other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the protection scope of the present invention.

The technical scheme of the invention is further explained by combining the specific examples as follows:

example 1

A preparation method of a functionalized polyimide composite material comprises the following steps:

(1) preparation of Polyamic acid microspheres

Weighing 20g of polyamic acid with the solid content of 18 wt%, adding the polyamic acid into 100ml of N, N-dimethylformamide solution, stirring for 2h, then transferring the polyamic acid into a constant-temperature constant-humidity box with the humidity of 98% and the temperature of 30 ℃ for 16h, collecting a product, centrifugally washing the product by using deionized water, and drying the product to obtain polyamic acid microspheres;

(2) modification of polyamide acid microspheres

Firstly, 1g of polyamic acid microsphere powder is added into 200ml of polyvinyl alcohol aqueous solution (0.04g/ml) and uniformly dispersed for 1h through ultrasonic treatment. Then, the polyamide acid microspheres are centrifuged to obtain the polyamide acid microspheres coated with a layer of polyvinyl alcohol.

(3) Preparation of graphene oxide coated polyamide acid microspheres

Dispersing the microspheres obtained in the step (2) in 200ml of deionized water after ultrasonic treatment, and mixing the microspheres with 100ml of 1mg/ml graphene oxide solution. And stirring the mixed solution for 1h, and washing the precipitate with deionized water to obtain the graphene oxide coated polyamide acid microspheres.

(4) Preparation of functional polyimide microsphere by thermal imidization method

And (3) drying the functionalized polyamic acid composite microspheres prepared in the step (2) at 60 ℃ for 2h, then putting the microspheres into a muffle furnace for heating, heating to 200 ℃ at a heating rate of 5 ℃/min, preserving heat for 1h, heating to 300 ℃ at a heating rate of 5 ℃/min, and preserving heat for 1h to obtain the graphene oxide coated polyimide composite microspheres.

The scanning electron microscope is performed on the prepared polyimide composite microspheres, and the result is shown in fig. 1, as can be seen from fig. 1, after graphene oxide is coated, the surface of the original polyimide microsphere with a smooth surface is wrinkled, and the graphene oxide is coated more uniformly.

Example 2

(1) Preparation of Polyamic acid microspheres

(2) preparation of aluminum oxide coated polyamide acid microspheres

Firstly, 1g of polyamic acid microsphere powder is added into 500ml of aqueous solution with the pH value of 4, and the solution is evenly dispersed for 1 hour through ultrasonic treatment. And then 0.3g of aluminum oxide powder is weighed and ultrasonically dispersed into an aqueous solution with the pH value of 4, the two solutions are stirred for 1 hour, and then the two solutions are washed and precipitated for 3 times by deionized water to obtain the polyamic acid microspheres coated by the aluminum oxide.

(3) Preparation of functional polyimide microsphere by thermal imidization method

And (3) drying the functionalized polyamic acid composite microspheres prepared in the step (2) at 60 ℃ for 2h, then putting the microspheres into a muffle furnace for heating, heating to 200 ℃ at a heating rate of 5 ℃/min, preserving heat for 1h, heating to 300 ℃ at a heating rate of 5 ℃/min, and preserving heat for 1h to obtain the polyimide composite microspheres coated with aluminum oxide.

The result of scanning electron microscopy on the prepared polyimide composite microsphere is shown in fig. 2, and as can be seen from fig. 2, a lot of granular aluminum oxide appears on the surface of the polyimide microsphere, which indicates that the aluminum oxide is successfully adsorbed on the surface of the PI microsphere through electrostatic adsorption.

Example 3

The preparation method is the same as that in example 2, except that the pH value of the aqueous solution in the step (2) is 5, the functional material is titanium dioxide, and the polyimide composite microsphere coated with titanium dioxide is prepared.

Scanning electron microscopy was performed on the polyimide composite microspheres prepared above, and the results are shown in fig. 3.

Example 4

The preparation method was the same as example 3 except that the mass of titanium dioxide in step (2) was 0.15g, as a comparative example of example 3.

Scanning electron microscopy was performed on the polyimide composite microspheres prepared above, and the results are shown in fig. 4.

Example 5

The preparation method was the same as example 3 except that the mass of titanium dioxide in step (2) was 0.2g, as a comparative example of example 3.

Scanning electron microscopy was performed on the polyimide composite microspheres prepared above, and the results are shown in fig. 5.

As can be seen from fig. 3, 4 and 5, the nano-scale titanium dioxide is successfully adsorbed on the surface of the polyimide microsphere through the electrostatic adsorption effect, and the adsorption amount can be controlled by controlling the addition amount of the titanium dioxide.

Blank polyimide microspheres, 15 wt% of titanium dioxide coated polyimide microspheres prepared in example 4 and 30 wt% of titanium dioxide coated polyimide microspheres prepared in example 3 are respectively added into rhodamine B solution with the same concentration, the change of the concentration of rhodamine B in the solution along with time is tested, the prepared degradation curve is shown in FIG. 6(a), and the degradation effect pair is shown in FIG. 6 (B); as can be seen from FIG. 6, after the titanium dioxide is loaded, the polyimide composite microspheres have the performance of photocatalytic degradation of rhodamine B, and the degradation efficiency is improved along with the increase of the loading amount of the titanium dioxide.

It should be understood by those skilled in the art that the foregoing is only illustrative of several embodiments of the invention, and not of all embodiments. It should be noted that many variations and modifications are possible to those skilled in the art, and all variations and modifications that do not depart from the gist of the invention are intended to be within the scope of the invention as defined in the appended claims.

Claims

1. The functionalized polyimide composite microsphere is characterized in that the particle size of the functionalized polyimide composite microsphere is 0.5-10 mu m, the functionalized polyimide composite microsphere is formed by compounding a polyimide microsphere and a functional material according to the mass ratio of 100 (1-40), and the functional material is uniformly coated on the surface of the polyimide microsphere.

2. The functionalized polyimide composite microsphere according to claim 1, wherein the functional material is one or a combination of two or more of graphene oxide, silicon dioxide, titanium dioxide, aluminum oxide, ferroferric oxide, boron nitride, graphene nanosheets and nano silver.

3. The functionalized polyimide composite microsphere according to claim 1, wherein the bonding force between the functional material and the polyimide microsphere is electrostatic adsorption force and hydrogen bonding.

4. A method for preparing the functionalized polyimide composite microsphere according to any one of claims 1 to 3, comprising the following steps:

s4, preparing functional polyimide microspheres: and (4) drying the functionalized polyamic acid composite microsphere prepared in the step (S3) at the temperature of 50-90 ℃ for 2-4h, raising the temperature to 220 ℃ at the heating rate of 1-10 ℃/min, preserving the heat for 1-3h, raising the temperature to 300 ℃ at the heating rate of 1-10 ℃/min, and preserving the heat for 1-2h to obtain the functionalized polyimide composite microsphere.

5. The method of claim 4, wherein the organic solvent in step S1 is one of N, N-dimethylformamide, N-dimethylacetamide, cyclohexane and chloroform.

6. The method for preparing the functionalized polyimide composite microspheres according to claim 4, wherein the water-soluble polymer in the step S2 is one of polyvinylpyrrolidone, polyvinyl alcohol, polyurethane, polyethylene glycol and dopamine hydrochloride.