CN111548529B - Polyimide-based graphene composite foam material with multilevel structure and preparation method thereof - Google Patents

Polyimide-based graphene composite foam material with multilevel structure and preparation method thereof Download PDF

Info

Publication number
CN111548529B
CN111548529B CN202010472223.3A CN202010472223A CN111548529B CN 111548529 B CN111548529 B CN 111548529B CN 202010472223 A CN202010472223 A CN 202010472223A CN 111548529 B CN111548529 B CN 111548529B
Authority
CN
China
Prior art keywords
polyimide
graphene
polyamic acid
foam
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Active
Application number
CN202010472223.3A
Other languages
Chinese (zh)
Other versions
CN111548529A (en
Inventor
刘天西
蒲磊
王子成
樊玮
侯豪情
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Jiangnan University
Original Assignee
Jiangnan University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Jiangnan University filed Critical Jiangnan University
Priority to CN202010472223.3A priority Critical patent/CN111548529B/en
Publication of CN111548529A publication Critical patent/CN111548529A/en
Application granted granted Critical
Publication of CN111548529B publication Critical patent/CN111548529B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

Links

Images

Classifications

    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/36—After-treatment
    • C08J9/40—Impregnation
    • C08J9/42—Impregnation with macromolecular compounds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/36—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
    • C08J9/36—After-treatment
    • C08J9/40—Impregnation
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2379/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2361/00 - C08J2377/00
    • C08J2379/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2379/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J2479/00—Characterised by the use of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing nitrogen with or without oxygen, or carbon only, not provided for in groups C08J2461/00 - C08J2477/00
    • C08J2479/04—Polycondensates having nitrogen-containing heterocyclic rings in the main chain; Polyhydrazides; Polyamide acids or similar polyimide precursors
    • C08J2479/08—Polyimides; Polyester-imides; Polyamide-imides; Polyamide acids or similar polyimide precursors

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Carbon And Carbon Compounds (AREA)

Abstract

The invention discloses a polyimide-based graphene composite foam material with a multilevel structure and a preparation method thereof, and belongs to the technical field of porous foam materials. The preparation method takes polyimide foam as a framework, adopts the technologies of graded vacuum impregnation loading of a mixture (second stage) of graphene oxide and polyamic acid with different concentration ratios and graphene oxide (third stage), freeze drying, heat treatment and the like to prepare the polyimide-based graphene composite foam with a multistage structure. The polyimide-based graphene composite foam prepared by the invention has the advantages of stable structure, low shrinkage rate and high thermal stability, realizes effective absorption of incident electromagnetic waves under the condition of keeping good heat insulation and thermal stability, and has wider frequency bandwidth. The polyimide foam has excellent comprehensive performance, simple and easy preparation process, environmental protection and widened application range.

Description

Polyimide-based graphene composite foam material with multilevel structure and preparation method thereof
Technical Field
The invention relates to a polyimide-based graphene composite foam material with a multilevel structure and a preparation method thereof, and belongs to the technical field of porous foam materials.
Background
By foam is meant a porous material consisting of a variety of microporous solids, with the dispersed phase being a gas. The composite material has the characteristics of low density, high specific surface area, rich and stable pore structure, adjustable components, variable performance and the like, and has good application prospect in many fields such as buildings, automobiles, aerospace, household appliances, petrochemical plants, outdoor sports, electromagnetic shielding, electromagnetic absorption and the like.
For the polyimide foam, the polyimide foam has intrinsic electrical insulation property, so that the polyimide foam has poor reflection loss on electromagnetic waves and does not have good electromagnetic absorption capacity, so that the composite foam prepared by adding conductive graphene can adjust the impedance matching property of the composite foam to obtain good electromagnetic absorption performance, but the graphene/polyimide composite material has relatively narrow microwave absorption frequency bandwidth due to single component impedance property. In addition, in the field of building electromagnetic protection materials, the materials are required to have a certain heat insulation capability besides good electromagnetic protection capability; in the field of electromagnetic shielding materials such as airplanes, in addition to the requirement for lightweight materials, materials are also required to have certain heat resistance.
Disclosure of Invention
[ problem ] to provide a method for producing a semiconductor device
The polyimide foam has intrinsic electrical insulation property, does not have microwave absorption capacity, is compounded with conductive graphene to obtain the graphene/polyimide composite material with good microwave absorption performance, and has relatively narrow microwave absorption frequency bandwidth due to single component impedance property. In addition, if the graphene/polyimide composite material is expected to be applied to the field of electromagnetic protection materials such as buildings and airplanes, the material is required to have certain heat insulation and heat resistance.
[ technical solution ] A
In order to solve the problems, the invention provides a polyimide-based graphene composite foam material with a multilevel structure and a preparation method thereof.
The preparation method takes polyimide foam as a framework, adopts the technologies of graded vacuum impregnation loading of a mixture (second stage) of graphene oxide and polyamic acid with different concentration ratios and graphene oxide (third stage), freeze drying, heat treatment and the like to prepare the polyimide-based graphene composite foam with a multistage structure. On one hand, the polyimide foam as a framework has rich pore channel structures, excellent mechanical stability and good heat-insulating property; on the other hand, the composite foam has excellent broadband strong microwave absorption capacity by carrying out graded impregnation on the graphene oxide and polyamide acid mixture and graphene oxide with different concentration ratios and carrying out heat treatment on the graphene oxide, so that the impedance distribution characteristic of the composite foam can be adjusted, and the multistage attenuation capacity of the composite foam on electromagnetic waves entering a foam framework structure is improved. Meanwhile, the thermal stability of the composite foam can be further improved after the added graphene oxide is subjected to heat treatment and reduced to reduced graphene oxide.
Specifically, a first object of the present invention is to provide a method for preparing a polyimide-based graphene composite foam material having a multilevel structure, the method comprising the steps of:
(1) preparing polyimide foam: uniformly mixing the water-soluble polyamic acid prepolymer, water and triethylamine, carrying out sol-gel reaction to obtain polyamic acid hydrogel, freeze-drying the polyamic acid hydrogel, and then carrying out heat treatment to obtain polyimide foam;
(2) preparing two-stage polyimide-graphene/polyimide composite foam: dispersing graphene oxide in water to obtain graphene oxide dispersion liquid, dissolving a water-soluble polyamic acid prepolymer in water to obtain a polyamic acid solution, stirring and mixing the graphene oxide dispersion liquid and the polyamic acid solution, immersing the polyimide foam prepared in the step (1) in the mixed solution by adopting a vacuum impregnation method, and after adsorption saturation, carrying out freeze drying and heat treatment on the polyimide foam to obtain two-stage polyimide-graphene/polyimide composite foam;
(3) preparing three-stage polyimide-graphene/polyimide-graphene composite foam: and (3) dispersing graphene oxide in water to obtain a graphene oxide dispersion solution, immersing the two-stage polyimide-graphene/polyimide composite foam prepared in the step (2) in the graphene oxide dispersion solution by adopting a vacuum impregnation method, and after adsorption saturation, carrying out freeze drying and heat treatment on the two-stage polyimide-graphene/polyimide-graphene composite foam to obtain the three-stage polyimide-graphene/graphene composite foam.
In one embodiment of the present invention, the polyimide foam prepared in step (1) is named as PI; the two-stage polyimide-graphene/polyimide composite bubble prepared in the step (2)Foam is named as PI-GPxWherein x represents the proportion of the concentration of the graphene oxide in the load carrier; the three-stage polyimide-graphene/polyimide-graphene composite foam prepared in the step (3) is named as PI-GPx-rGO。
In one embodiment of the present invention, the preparation method of the water-soluble polyamic acid prepolymer in step (1) comprises: dissolving diamine monomer in polar solvent, adding dibasic anhydride monomer, polymerizing in ice-water bath, adding organic amine, reacting to obtain water soluble polyamic acid solution, precipitating, and freeze drying to obtain water soluble polyamic acid prepolymer.
In one embodiment of the present invention, the molar ratio of the diamine monomer, the polar solvent, the dicarboxylic anhydride monomer and the organic amine in step (1) is 1:27.5:0.275: 1.
In one embodiment of the present invention, the diamine monomer is p-phenylenediamine or 4, 4' -diaminodiphenyl ether; the binary anhydride monomer is any one of pyromellitic dianhydride, biphenyl tetracarboxylic dianhydride or diphenyl ether tetracarboxylic dianhydride; the polar solvent is any one of N, N '-dimethylacetamide, N-methylpyrrolidone or N, N' -dimethylformamide; the organic amine is any one of triethylamine or dipropylamine.
In one embodiment of the present invention, in the method for preparing polyimide foam in step (1), the water-soluble polyamic acid, triethylamine and water are mixed in a mass ratio of (1-10): (0.5-5): 100 are mixed.
In one embodiment of the present invention, the original crystalline flake graphite of the graphene oxide in the step (2) is 80-400 mesh, and the concentration of the prepared graphene oxide dispersion is 2-10 mg/mL.
In one embodiment of the present invention, triethylamine is further added when the polyamic acid solution is prepared in step (2), and the specific method is to dissolve the water-soluble polyamic acid prepolymer and triethylamine in water to prepare a polyamic acid/triethylamine solution.
In one embodiment of the present invention, the concentration ratio of the graphene oxide dispersion liquid to the polyamic acid solution in step (2) is (1: 4) to (4: 1).
In one embodiment of the present invention, the concentration ratio of the graphene oxide dispersion liquid to the polyamic acid solution in step (2) is 1: 2.
in one embodiment of the invention, the vacuum impregnation in the step (2) and the step (3) is performed in a vacuum drying oven with a vacuum degree of 15-30 Pa and an impregnation time of 24-48 h.
In one embodiment of the present invention, the freeze-drying and heat-treatment in steps (1), (2) and (3) are performed in the same manner, specifically as follows: the freeze drying process comprises the following steps: firstly, carrying out low-temperature constant-temperature reaction bath at the temperature of-60 to-196 ℃ for 120 to 240 min; then, freeze-drying by using a vacuum freeze-drying machine, wherein the vacuum degree is 0.1-10 Pa, and the drying time is 72-100 h; the heat treatment process comprises the following steps: carrying out heat treatment on the freeze-dried product, wherein the heat treatment conditions are as follows: and (3) carrying out heat treatment for 0.5-2.5 h at 50-350 ℃ in an inert atmosphere, wherein the inert atmosphere comprises nitrogen, helium and argon.
In one embodiment of the present invention, the concentration of the graphene oxide dispersion in the step (3) is 4mg/mL to 16 mg/mL.
In one embodiment of the present invention, the ratio of the concentration of the graphene oxide dispersion liquid in the step (3) to the concentration of the graphene oxide dispersion liquid in the step (2) is 1: 1.
the second purpose of the invention is to provide the polyimide-based graphene composite foam material with the multilevel structure prepared by the method.
The third purpose of the invention is to provide the application of the polyimide-based graphene composite foam material with the multilevel structure in the fields of buildings, automobiles, aerospace, household appliances, electromagnetic shielding, electromagnetic absorption and the like.
[ advantageous effects ]:
(1) when the polyimide and the reduced graphene oxide are coupled together, the mismatch characteristic impedance from the reduced graphene oxide is corrected, and the weak dielectric loss from the polyimide is enhanced at the same time, so that the controllable construction of the polyimide-graphene/polyimide-graphene composite foam with the multilevel structure is realized, and compared with the two-stage composite of the polyimide-graphene/polyimide, the multi-reflection among the pore structures in the foam is effectively enhanced by introducing the third-stage graphene layer; compared with pure graphene foam, the introduction of the polyimide layer and the graphene/polyimide impedance gradient layer can effectively enhance the attenuation of electromagnetic waves entering the skeleton structure through the graphene layer, and finally the composite foam material with wide-frequency and strong-microwave absorption performance is obtained.
(2) According to the invention, the polyimide foam is used as a framework to load the reduced graphene oxide, so that the porous structure of the reduced graphene oxide can be maintained, and the porous structure contains a large amount of air, so that the diffusion of heat can be effectively blocked, and the good heat insulation performance of the reduced graphene oxide can be maintained. Meanwhile, the load of the reduced graphene oxide is low, and most of the reduced graphene oxide is distributed on the pore wall of the syntactic foam in a discontinuous transverse size and a unique structure, so that the transmission and heat transfer of electrons can be maintained, and sufficient synergistic action and interface effect are generated, so that the thermal stability of the syntactic foam is improved. Specifically, the initial thermal decomposition temperature of PI is 487.9 ℃. And PI-GP1/2，PI-GP1/3-rGO，PI-GP1/2-rGO and PI-GP2/3-the initial thermal decomposition temperatures of rGO are 515.9 ℃, 548.2 ℃, 526.3 ℃ and 525.6 ℃ respectively. At the same time, PI, PI-GP1/2，PI-GP1/3-rGO，PI-GP1/2-rGO and PI-GP2/3-The thermal conductivity of rGO is 45.27 mW.m-1·K-1、46.85mW·m-1·K-1、46.88mW·m-1·K-1、46.36mW·m-1·K-1And 41.99 mW.m-1·K-1The syntactic foam still retains thermal insulation properties comparable to PI foam.
(3) According to the invention, the mixture (second stage) of graphene oxide and polyamide acid and the graphene oxide (third stage) with different concentration ratios are loaded through graded vacuum impregnation, and after the graphene oxide and the polyamide acid are subjected to heat treatment, the impedance matching performance of the composite foam skeleton structure can be effectively adjusted, so that the composite foam has excellent electromagnetic wave reflection loss capability. In particular, PI-GP1/3rGO at a thickness of 4mm and a frequency of 10.39GHzThe minimum Reflection Loss (RL) can reach-32.87 dB, and the effective absorption bandwidth is 6.22GHz (8.26-14.48 GHz).
(4) The preparation process is simple and easy to operate, is simple, green and environment-friendly, and is a method for enhancing the performance of the polyimide foam with wide application prospect.
Drawings
Fig. 1 is a scanning electron microscope image of the multi-stage polyimide-based graphene composite foam prepared in examples 1 to 3.
Fig. 2 is a graph of thermal conductivity of the multi-stage polyimide-based graphene composite foam prepared in examples 1-3.
Fig. 3 is a graph showing the thermal weight loss of the multi-stage polyimide-based graphene composite foam prepared in examples 1 to 3.
Fig. 4 is an electromagnetic wave reflection loss graph of the multi-stage polyimide-based graphene composite foam prepared in examples 1 to 3.
Detailed Description
The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.
Example 1
Preparation of three-stage polyimide-graphene/polyimide-graphene composite foam (PI-GP)1/2-rGO)
(1) Preparation of polyimide foam (PI)
N, N '-dimethylacetamide is used as a solvent, and 4, 4' -diaminodiphenyl ether and pyromellitic dianhydride in equal molar ratio are subjected to condensation polymerization reaction in an ice-water bath to prepare polyamic acid with the solid content of 15%. The specific process is as follows: 8.0096g of 4,4 '-diaminodiphenyl ether is dissolved in 95.57g N, N' -dimethylacetamide, 8.8556g of pyromellitic dianhydride is added, and the mixture is reacted in an ice-water bath at 0 ℃ for 5 hours. Then, 4.0476g of triethylamine was added, and the reaction was continued for 5 hours to prepare a water-soluble polyamic acid solution having a solid content of 15%. Hanging the prepared water-soluble polyamic acid at a high position, dripping the water-soluble polyamic acid into deionized water in a flowing wire mode for precipitation, displacing an organic solvent, washing the precipitate for 2-3 times by using the deionized water, and finally performing freeze drying by using a vacuum freeze dryer with the vacuum degree of 1Pa and the temperature of-80 ℃ for 72 hours until the water-soluble polyamic acid prepolymer is ready for use.
Taking 10mL of deionized water, 0.3g of water-soluble polyamic acid prepolymer and 0.15g of triethylamine, uniformly mixing, placing the uniformly mixed mixture in a refrigerator at 4 ℃ for 18h to obtain polyamic acid hydrogel after finishing a sol-gel reaction, obtaining the polyamic acid hydrogel after 24h of a sol-gel process, and freeze-drying and carrying out heat treatment to obtain polyimide foam which is named as PI. The freeze drying process comprises the following steps: firstly, carrying out low-temperature constant-temperature reaction bath at the temperature of-60 ℃ for 200 min; then, freeze-drying by using a vacuum freeze-drying machine, wherein the vacuum degree is 1Pa, and the drying time is 72 h; finally, carrying out heat treatment on the freeze-dried product, wherein the heat treatment conditions are as follows: and (3) carrying out heat treatment for 2h at 250 ℃ under an inert atmosphere, wherein the inert atmosphere comprises nitrogen, helium and argon.
(2) Preparation of two-stage polyimide-graphene/polyimide composite foam (PI-GP)1/2)
Preparing graphene oxide: the preparation method comprises the following steps of carrying out oxidation reaction on flake graphite serving as a raw material, concentrated sulfuric acid and concentrated phosphoric acid serving as intercalation agents and potassium permanganate serving as an oxidant in a constant-temperature water bath to prepare graphene oxide. The specific process is as follows: slowly adding 3.0g of crystalline flake graphite, 360mL of concentrated sulfuric acid and 40mL of concentrated phosphoric acid into a 1000mL three-neck flask, properly performing magnetic stirring, slowly adding 18g of potassium permanganate, continuously performing magnetic stirring for 10min, adjusting the temperature of a water bath to 50 ℃, and stirring at a constant speed for 12 h. After the reaction is completed, the mixed solution is slowly poured into a beaker containing 400mL of deionized water, and is uniformly stirred by a glass rod. Then H is put into2O2(30%) the aqueous solution was dropped dropwise into the mixture, and stirred until the mixture turned golden yellow, after which the mixture was allowed to stand overnight. Centrifuging the mixed solution to remove a large amount of residual acid, metal ions and the like in the mixed solution; then respectively adopting 5 percent HCl solution,And dialyzing with deionized water until the pH value is close to 5-6. And putting the obtained hydrosol of the graphene oxide into a freeze dryer for drying to obtain the graphene oxide.
And (2) loading a mixed solution of polyamic acid and graphene oxide with the concentration ratio of polyamic acid to graphene oxide being 1:1 on the polyimide foam (PI) prepared in the step (1). The specific operation method comprises the following steps: dispersing 40mg of graphene oxide in 10mL of deionized water, carrying out ultrasonic treatment for 5-20min at room temperature with the power of 40KW to prepare a graphene oxide dispersion liquid with the concentration of 4mg/mL, and dissolving a water-soluble polyamic acid prepolymer and triethylamine in water to prepare a mixed solution of a polyamic acid solution and a triethylamine solution with the concentrations of 4mg/mL and 2mg/mL respectively. The prepared graphene oxide dispersion liquid and the polyamic acid/triethylamine mixed solution are mixed under magnetic stirring, polyimide foam (PI) is put into the mixed solution, and impregnation loading is carried out at room temperature under a vacuum environment with a vacuum degree of 15pa to enable the mixture to be saturated in adsorption. Then taking out the mixture to carry out freeze drying and heat treatment, and finally obtaining the two-stage polyimide-graphene/polyimide composite foam which is named as PI-GP1/2. The freeze drying and heat treatment process is the same as the freeze drying and heat treatment process in the step (1).
(3) Preparation of three-stage polyimide-graphene/polyimide-graphene composite foam (PI-GP)1/2-rGO)
The two-stage polyimide-graphene/polyimide composite foam (PI-GP) prepared in the step (2)1/2) On the basis of the preparation method, graphene oxide is loaded to prepare the three-level polyimide-graphene/polyimide-graphene composite foam. The specific operation method comprises the following steps: dispersing 4g of graphene oxide in 10mL of deionized water, and carrying out ultrasonic treatment for 5-20min in ultrasonic waves with the power of 40KW and the room temperature to prepare graphene oxide dispersion liquid with the concentration of 4 mg/mL. Preparing the two-stage polyimide-graphene/polyimide composite foam (PI-GP) prepared in the step (2)1/2) The resultant was put into a graphene oxide dispersion, and the graphene oxide dispersion was subjected to impregnation loading at room temperature under a vacuum condition of a degree of vacuum of 15pa to saturate the adsorption. Then taking out the mixture to carry out freeze drying and heat treatment, and finally obtaining the tertiary polyimide-graphene/polyimideAmine-graphene syntactic foam, named PI-GP1/2-rGO. The freeze drying and heat treatment process is the same as the freeze drying and heat treatment process in the step (1).
Example 2
Preparation of three-stage polyimide-graphene/polyimide-graphene composite foam (PI-GP)2/3-rGO)
(1) Preparation of polyimide foam (PI): the preparation method is the same as that of example 1;
(2) preparation of two-stage polyimide-graphene/polyimide composite foam (PI-GP)1/2): compared with the example 1, the graphene oxide and polyamic acid mixed solution with different concentration ratios is loaded. The specific operation method comprises the following steps: preparing a graphene oxide dispersion liquid with the concentration of 4mg/mL under an ultrasonic condition; dissolving the water-soluble polyamic acid prepolymer and triethylamine in water to prepare a mixed solution of a polyamic acid solution and a triethylamine solution with the concentrations of 2mg/mL and 1mg/mL respectively. And mixing the prepared graphene oxide dispersion liquid and the polyamic acid/triethylamine mixed solution under magnetic stirring. And (2) putting the polyimide foam (PI) prepared in the step (1) into the mixed solution, and carrying out impregnation loading at room temperature in a vacuum environment to ensure that the polyimide foam is saturated in adsorption. Then taking out the mixture to carry out freeze drying and heat treatment, and finally obtaining the two-stage polyimide-graphene/polyimide composite foam which is named as PI-GP2/3；
(3) Preparation of three-stage polyimide-graphene/polyimide-graphene composite foam (PI-GP)2/3-rGO): the two-stage polyimide-graphene/polyimide composite foam (PI-GP) prepared in the step (2)1/2) Loading graphene oxide on the basis, wherein the loading method is the same as that in the step (3) in the embodiment 1, and finally obtaining the three-stage polyimide-graphene/polyimide-graphene composite foam which is named as PI-GP2/3-rGO。
Example 3
Preparation of three-stage polyimide-graphene/polyimide-graphene composite foam (PI-GP)1/3-rGO)
(1) Preparation of polyimide foam (PI): the preparation method is the same as that of example 1;
(2) preparation of two-stage polyimide-graphene/polyimide composite foam (PI-GP)1/2): compared with the example 1, the graphene oxide and polyamic acid mixed solution with different concentration ratios is loaded. The specific operation method comprises the following steps: preparing a graphene oxide dispersion liquid with the concentration of 4mg/mL under an ultrasonic condition; dissolving the water-soluble polyamic acid prepolymer and triethylamine in water to prepare mixed solution of polyamic acid solution and triethylamine solution with the concentration of 8mg/mL and 4mg/mL respectively. And mixing the prepared graphene oxide dispersion liquid and the polyamic acid/triethylamine mixed solution under magnetic stirring. And (2) putting the polyimide foam (PI) prepared in the step (1) into the mixed solution, and carrying out impregnation loading at room temperature in a vacuum environment to ensure that the polyimide foam is saturated in adsorption. Then taking out the mixture to carry out freeze drying and heat treatment, and finally obtaining the two-stage polyimide-graphene/polyimide composite foam which is named as PI-GP1/3；
(3) Preparation of three-stage polyimide-graphene/polyimide-graphene composite foam (PI-GP)1/3-rGO): the two-stage polyimide-graphene/polyimide composite foam (PI-GP) prepared in the step (2)1/3) Loading graphene oxide on the basis, wherein the loading method is the same as that in the step (3) in the embodiment 1, and finally obtaining the three-stage polyimide-graphene/polyimide-graphene composite foam which is named as PI-GP1/3-rGO。
Characterization and performance testing:
1. the determination method of the scanning electron microscope image comprises the following steps: scanning electron micrographs of the composite foam were taken using a JSM 6490LV field emission electron microscope, JEOL, Japan.
2. The method for measuring the thermal conductivity comprises the following steps: the thermal conductivity of the multigrade syntactic foam was measured using a Hot Disk TPS 2500S thermal constant analyzer.
3. The method for measuring the thermal weight loss curve comprises the following steps: thermogravimetric analysis (TGA) was performed by using a Meuterle-Tolydol TGA/DSC1/1100SF thermogravimetric analyzer under nitrogen atmosphere at a heating rate of 10 ℃/min.
4. The method for measuring the reflection loss of the electromagnetic wave comprises the following steps: electromagnetic parameters of the composite foam were measured by a coaxial line method using an Agilent 8720ET vector network analyzer at a frequency range of 0.5-18 GHz.
5. The reflection loss and the impedance of the polyimide-based graphene composite foam with different thicknesses are obtained through fitting calculation:
based on the generalized transmission line theory, the Reflection Loss (RL) value of the syntactic foam is calculated according to the following equation (1).
Figure BDA0002514654620000071
Wherein Z0Representing the impedance of air, ZinIs the normalized input impedance of the microwave absorbing layer, and can be expressed by equation (2).
Figure BDA0002514654620000072
The various foam materials prepared in examples 1-3 were tested for scanning electron microscopy, thermal conductivity, thermal stability and microwave absorption, and the results are shown in FIGS. 1-4.
FIG. 1 is a scanning electron microscope image of a polyimide-based graphene composite foam of a multilevel structure prepared in examples 1 to 3; wherein: (a) is PI, (b) is PI-GP1/2(c) is PI-GP1/3-rGO, (d) is PI-GP1/2-rGO, (e) is PI-GP2/3-rGO. FIG. 1(b, c) shows that there are many small lamellae inside the foam cells and the cell wall thickness is increased. Graphene and polyimide were shown to be payload on the PI backbone. And fig. 1(d, e) shows that as the concentration ratio of the graphene oxide supported in the second stage increases, the flake structure inside the syntactic foam gradually increases and the cell wall thickness increases. Meanwhile, the pore diameter in the composite foam is gradually oriented to form a layered structure, and the interlayer distance is gradually reduced. The concentration ratio of the graphene and the polyimide loaded on the second stage is changed, so that the internal structure of the composite foam can be effectively adjusted.
Fig. 2 is a graph of thermal conductivity of the multilevel structure polyimide-based graphene composite foam prepared in examples 1 to 3. As can be seen from FIG. 2, PI, PI-GP1/2，PI-GP1/3-rGO，PI-GP1/2-rGO and PI-GP2/3-The thermal conductivity of rGO is 45.27 mW.m-1·K-1、46.85mW·m-1·K-1、46.88mW·m-1·K-1、46.36mW·m-1·K-1And 41.99 mW.m-1·K-1. It was demonstrated that the syntactic foam still maintains thermal insulation properties comparable to PI foam.
Fig. 3 is a graph showing the thermal weight loss curves of the polyimide-based graphene composite foams of the multilevel structures prepared in examples 1 to 3. As can be seen from fig. 3, the initial thermal decomposition temperature of PI is 487.9 ℃. And PI-GP1/2，PI-GP1/3-rGO，PI-GP1/2-rGO and PI-GP2/3The initial thermal decomposition temperatures of rGO were 515.9 ℃, 548.2 ℃, 526.3 ℃ and 525.6 ℃ respectively. As the number of stages of loading increases, the initial thermal decomposition temperature of the syntactic foam increases. With the increase of the loading amount of the second-stage polyimide, the initial thermal decomposition temperature of the composite foam material is increased, and the structure of the graphene/polyimide composite foam material is more stable due to the interfacial compatibility of the polyimide and the graphene.
Fig. 4 is a microwave absorption diagram of the polyimide-based graphene composite foam of the multilevel structure prepared in examples 1 to 3. Of the 5 samples, PI has the lowest complex dielectric constant and dielectric loss tangent, and is not sufficient to effectively dissipate the energy of the incident electromagnetic wave, so that PI has poor reflection loss performance (>-10dB)。PI-GP1/2The minimum RL value at 8.16GHz and a thickness of 5.0mm is-20.15 dB, at which point the effective absorption bandwidth is 3.73GHz (6.67-10.40 GHz). PI-GP1/2Minimum RL value of-24.86 dB at 17.93GHz and thickness of 2mm for rGO, and effective absorption bandwidth (RL)<-10dB) to 3.97GHz, which indicates a great improvement in its microwave absorption performance. PI-GP2/3rGO provides relatively poor microwave absorption characteristics over the frequency range studied (fig. 4e), with reflection losses consistently greater than-10.0 dB when the thickness of the absorber is tuned from 1.0mm to 4.0 mm. And when PI-GP2/3The minimum RL value of rGO is only-12.47 dB at a frequency of 15.91GHz and a thickness of 5mm, and the effective absorption bandwidth is 4.51GHz (13.49-18.00 GHz). And PI-GP2/3PI-GP comparison with rGO1/2The rGO is slightly improved over the medium and high frequency range (8.0-18.0GHz) (fig. 4d), with the strongest reflection loss being-24.86 dB at 17.93GHz when the thickness of the absorbing material is set to 2mm, with an effective absorption bandwidth of 3.97GHz (14.13-18.00 GHz). PI-GP1/3The wave absorbing performance of the-rGO is higher than that of PI-GP1/2-rGO and PI-GP2/3-rGO is even more excellent (fig. 4c), especially at absorber thickness of 4mm, with minimum RL values as high as-32.87 dB at 10.39GHz, where the effective absorption bandwidth is 6.22GHz (8.26-14.48 GHz). Even for other thicknesses, PI-GP1/3-rGO can still keep its minimum reflection loss value above-10.0 dB. This shows that the absorption performance of the composite foam for microwaves is significantly improved as the concentration ratio of the graphene oxide/polyamic acid loaded in the second stage is reduced.
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.

Claims (9)

1. A method for preparing a polyimide-based graphene composite foam material with a multilevel structure is characterized by comprising the following steps:
(1) preparing polyimide foam: uniformly mixing the water-soluble polyamic acid prepolymer, water and triethylamine, carrying out sol-gel reaction to obtain polyamic acid hydrogel, freeze-drying the polyamic acid hydrogel, and then carrying out heat treatment to obtain polyimide foam;
(2) preparing two-stage polyimide-graphene/polyimide composite foam: dispersing graphene oxide in water to obtain graphene oxide dispersion liquid, dissolving a water-soluble polyamic acid prepolymer in water to obtain a polyamic acid solution, stirring and mixing the graphene oxide dispersion liquid and the polyamic acid solution, immersing the polyimide foam prepared in the step (1) in the mixed solution by adopting a vacuum impregnation method, and after adsorption saturation, carrying out freeze drying and heat treatment on the polyimide foam to obtain two-stage polyimide-graphene/polyimide composite foam; wherein the concentration ratio of the graphene oxide dispersion liquid to the polyamic acid solution is (1: 4) - (4: 1);
(3) preparing three-stage polyimide-graphene/polyimide-graphene composite foam: and (3) dispersing graphene oxide in water to obtain a graphene oxide dispersion solution, immersing the two-stage polyimide-graphene/polyimide composite foam prepared in the step (2) in the graphene oxide dispersion solution by adopting a vacuum impregnation method, and after adsorption saturation, carrying out freeze drying and heat treatment on the two-stage polyimide-graphene/polyimide composite foam to obtain the three-stage polyimide-graphene/polyimide-graphene composite foam.
2. The method according to claim 1, wherein the water-soluble polyamic acid prepolymer in the step (1) is prepared by: dissolving diamine monomer in polar solvent, adding dibasic anhydride monomer, polymerizing in ice-water bath, adding organic amine, reacting to obtain water soluble polyamic acid solution, precipitating, and freeze drying to obtain water soluble polyamic acid prepolymer.
3. The method according to claim 1, wherein in the method for preparing the polyimide foam according to the step (1), the water-soluble polyamic acid, the triethylamine and the water are mixed in a mass ratio of (1-10): (0.5-5): 100 are mixed.
4. The method according to claim 1, wherein the original crystalline flake graphite of the graphene oxide in the step (2) has a size of 80-400 mesh, and the prepared graphene oxide dispersion has a concentration of 2-10 mg/mL.
5. The method of claim 1, wherein triethylamine is further added to the polyamic acid solution prepared in step (2), and the method comprises: dissolving the water-soluble polyamic acid prepolymer and triethylamine in water to prepare a polyamic acid/triethylamine solution.
6. The method according to claim 1, wherein the freeze-drying and heat-treatment in steps (1), (2) and (3) are performed in the same manner, as follows: the freeze drying process comprises the following steps: firstly, carrying out low-temperature constant-temperature reaction bath at the temperature of-60 to-196 ℃ for 120 to 240 min; then, freeze-drying by using a vacuum freeze-drying machine, wherein the vacuum degree is 0.1-10 Pa, and the drying time is 72-100 h; the heat treatment process comprises the following steps: carrying out heat treatment on the freeze-dried product, wherein the heat treatment conditions are as follows: and (3) carrying out heat treatment for 0.5-2.5 h at 50-350 ℃ in an inert atmosphere, wherein the inert atmosphere comprises nitrogen, helium and argon.
7. The method according to claim 1, wherein the concentration of the graphene oxide dispersion in the step (3) is 4mg/mL to 16 mg/mL.
8. The polyimide-based graphene composite foam material with the multilevel structure prepared by the method according to any one of claims 1 to 7.
9. The use of the polyimide-based graphene composite foam material having a multilevel structure according to claim 8 in the fields of construction, automobiles, aerospace, household appliances, electromagnetic shielding, and electromagnetic absorption.
CN202010472223.3A 2020-05-29 2020-05-29 Polyimide-based graphene composite foam material with multilevel structure and preparation method thereof Active CN111548529B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202010472223.3A CN111548529B (en) 2020-05-29 2020-05-29 Polyimide-based graphene composite foam material with multilevel structure and preparation method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202010472223.3A CN111548529B (en) 2020-05-29 2020-05-29 Polyimide-based graphene composite foam material with multilevel structure and preparation method thereof

Publications (2)

Publication Number Publication Date
CN111548529A CN111548529A (en) 2020-08-18
CN111548529B true CN111548529B (en) 2021-07-27

Family

ID=72000658

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010472223.3A Active CN111548529B (en) 2020-05-29 2020-05-29 Polyimide-based graphene composite foam material with multilevel structure and preparation method thereof

Country Status (1)

Country Link
CN (1) CN111548529B (en)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111909420B (en) * 2020-08-25 2022-04-22 哈尔滨工程大学 Preparation method and product of graphene/polyimide composite sponge flexible sensor
CN112094426B (en) * 2020-09-16 2021-11-16 江南大学 Impedance gradual change type graphene-based polyimide composite foam wave-absorbing material
CN114395252A (en) * 2021-12-30 2022-04-26 西北大学 Preparation method of graphene/polyimide composite sponge with multilevel structure
CN114591532B (en) * 2022-02-14 2023-04-18 青岛海洋新材料科技有限公司 Polyimide composite foam material with photocatalytic performance and preparation method and application thereof
CN114854087B (en) * 2022-05-13 2023-03-31 吉林大学 Polyimide composite material with double heat-conducting networks and preparation method thereof
CN115960387A (en) * 2023-02-09 2023-04-14 江西师范大学 Composite foam and preparation method thereof

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105694427A (en) * 2014-11-26 2016-06-22 中国科学院金属研究所 Application of graphene composite material electromagnetic shielding material
KR20180011483A (en) * 2016-07-15 2018-02-02 연세대학교 산학협력단 Melamine sponge structure comprising graphene oxide coating layer and manufacturing method thereof
CN109897213A (en) * 2019-03-25 2019-06-18 中南大学 A kind of electromagnetic shielding preparation method of flexible composite
KR20190099785A (en) * 2018-02-20 2019-08-28 한국과학기술원 Graphene foam and method for fabricating the graphene foam
CN110358142A (en) * 2019-07-11 2019-10-22 哈尔滨工程大学 The preparation method of the highly sensitive flexible compound sponge voltage sensitive sensor of wide temperature range

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106243379B (en) * 2016-07-23 2019-10-18 天津大学 A kind of electromagnetic shielding foamed composite and preparation method based on graphene oxide and polymer
WO2018157208A1 (en) * 2017-03-01 2018-09-07 The University Of Adelaide Acoustic graphene-containing compositions/materials and methods of formation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN105694427A (en) * 2014-11-26 2016-06-22 中国科学院金属研究所 Application of graphene composite material electromagnetic shielding material
KR20180011483A (en) * 2016-07-15 2018-02-02 연세대학교 산학협력단 Melamine sponge structure comprising graphene oxide coating layer and manufacturing method thereof
KR20190099785A (en) * 2018-02-20 2019-08-28 한국과학기술원 Graphene foam and method for fabricating the graphene foam
CN109897213A (en) * 2019-03-25 2019-06-18 中南大学 A kind of electromagnetic shielding preparation method of flexible composite
CN110358142A (en) * 2019-07-11 2019-10-22 哈尔滨工程大学 The preparation method of the highly sensitive flexible compound sponge voltage sensitive sensor of wide temperature range

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
"Light-Weight, Super-Elastic and Mechanically Flexible Graphene/Polyimide Nanocomposite Foam for Strain Sensor Application";Yuyang Qin，et al.;《Acs Nano》;20150824;第9卷(第9期);第1-28页 *

Also Published As

Publication number Publication date
CN111548529A (en) 2020-08-18

Similar Documents

Publication Publication Date Title
CN111548529B (en) Polyimide-based graphene composite foam material with multilevel structure and preparation method thereof
Du et al. Ultralight, highly compressible, thermally stable MXene/aramid nanofiber anisotropic aerogels for electromagnetic interference shielding
Pu et al. Polyimide-based graphene composite foams with hierarchical impedance gradient for efficient electromagnetic absorption
Dong et al. A multiscale hierarchical architecture of a SiC whiskers–graphite nanosheets/polypyrrole ternary composite for enhanced electromagnetic wave absorption
CN109942851B (en) Low-dielectric-constant polyimide hybrid film and application
CN115449121B (en) Polypyrrole coated polyimide hybrid aerogel/phase change material composite film with infrared/electromagnetic double stealth function and preparation method thereof
CN111410194A (en) Composite electromagnetic wave absorbing foam prepared from ZIF-67/melamine and preparation method thereof
CN114195197B (en) Magnetic porous carbon compound and preparation method and application thereof
CN114832741B (en) Preparation method of heat-conducting wave-absorbing composite aerogel and heat-conducting wave-absorbing composite aerogel
CN110498990B (en) Preparation method of C @ Ni composite material and electromagnetic shielding film
CN110951455B (en) Preparation method of light heat-insulating wave-absorbing material based on graphene
Lu et al. The effect of polymer polarity on the microwave absorbing properties of MWNTs
CN113861682B (en) Inorganic/organic inter-doped hydrophobic polyimide aerogel and preparation method thereof
CN114920978A (en) Preparation method of aerogel with electromagnetic shielding and sound absorption functions
CN114071982A (en) Honeycomb reduced graphene oxide foam/nickel nanoparticle wave absorbing agent and preparation method thereof
CN112094426B (en) Impedance gradual change type graphene-based polyimide composite foam wave-absorbing material
CN112646372A (en) Polyimide film with low dielectric constant and application thereof
CN113321844B (en) Graphene/polyimide composite foam wave-absorbing material with oriented pore structure and preparation method thereof
CN112911915B (en) Corrosion-resistant graphene-based magnetic composite foam wave-absorbing material and preparation method thereof
CN113403032A (en) Preparation method of silicon carbide composite material
CN114276150B (en) SiOCN ceramic aerogel wave-absorbing material and preparation method thereof
CN115385715B (en) Porous carbon-rich silicon-carbon-nitrogen ceramic heat absorption waveguide material and preparation method thereof
CN113698763B (en) ZIF-8 carbon nanotube polyimide porous film and preparation method thereof
CN114958301B (en) Carbon nano tube/Ni porphyrin loaded wave-absorbing material, preparation method and application thereof
CN116444855A (en) Photo/thermal response shape memory polyimide-based phase change composite material and preparation method thereof

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
GR01 Patent grant
GR01 Patent grant