Disclosure of Invention
In order to develop a high-performance material in the field of electronic chips and improve the heat conduction and wave absorption performance of the material, the application provides a preparation method of a heat conduction and wave absorption composite film and the heat conduction and wave absorption composite film.
In a first aspect, the application provides a method for preparing a heat-conducting wave-absorbing composite film, which adopts the following technical scheme:
a preparation method of a heat-conducting wave-absorbing composite film comprises the following preparation steps:
preparing MXene nanosheet dispersion liquid: etching the MAX phase material by using an etching agent to obtain an organ-shaped MXene phase, and washing and ultrasonically treating to obtain an MXene nanosheet dispersion liquid;
preparing composite slurry: uniformly mixing 0.03-0.15 g/LMXene nanosheet dispersion liquid and 0.5-2 g/L graphene oxide slurry, controlling the weight ratio of MXene nanosheets to graphene oxide to be (1-10) - (5-30), and performing ultrasonic dispersion to obtain composite slurry;
preparing a film: coating and drying the composite slurry to obtain a film;
and (3) post-treatment: and graphitizing the film, and rolling to obtain the heat-conducting wave-absorbing composite film.
By adopting the technical scheme, MAX phase materials are used as precursors, and an Al layer is removed by chemical etching of etchant such as hydrofluoric acid and lithium fluoride to obtain organ-shaped MXene phase, and the organ-shaped MXene phase is subjected to ultrasonic stripping treatment to obtain MXene nanosheet dispersion liquid;
the surfaces of the MXene nanosheets and the graphene oxide nanosheets both contain a large number of polar groups, the MXene nanosheets and the graphene oxide nanosheets are both two-dimensional materials, the MXene nanosheets can be assembled together with graphene oxide, a composite material can be formed through van der Waals force, hydrogen bonds and pi-pi conjugated stacking and crosslinking actions, and the composite material is stably suspended in a solvent to form composite slurry; uniformly coating the composite slurry on a substrate, and drying to remove the solvent to form a film;
the temperature of the graphitization treatment is generally 2300 ℃ or above, the graphene oxide is firstly reduced in the process of the graphitization treatment of the film, then atoms inside the film are partially rearranged, the defects of the film are repaired, the lamellar structure is increased, the size distribution of holes is uniform and fine, a stable multilayer heat conduction network is formed, the number of heat conduction paths of the heat conduction network is increased, and the heat conduction coefficient is improved to 2200W/(m.k); the multi-layer structure and the microporous structure of the heat conducting network can enable electromagnetic waves to be reflected/scattered for multiple times, so that a good wave absorbing effect is achieved, and the electromagnetic shielding efficiency reaches 105dB under the thickness;
and rolling the composite membrane shrunk during graphitization, and extending to obtain the composite membrane with high heat conductivity and wave absorption performance.
Optionally, in the post-treatment step, the temperature of the film graphitization treatment is 2500-3000 ℃, and the heat preservation treatment is carried out for 0.5-1 h.
Preferably, in the post-treatment step, the film graphitization treatment is performed under the protection of argon.
By adopting the technical scheme, the formed micropore structure is uniform and fine in the temperature range of the graphitization treatment, and the heat conduction performance and the wave absorption performance of the composite membrane are optimal; below this graphitization temperature range, the pores of the composite membrane are too large, reducing the thermal conductivity of the composite membrane.
Optionally, the specific operations of the preparation step of the MXene nanosheet dispersion liquid are as follows:
adding MAX phase materials into hydrofluoric acid with the concentration of 20-30 wt%, wherein the weight ratio of MAX phase materials to hydrofluoric acid is 1 (5-10), and stirring for 5-10 hours when the temperature is raised to 60-80 ℃ to obtain organ-shaped MXene phase materials; washing the organ-shaped MXene phase material in an ethanol water solution for at least 3 times, and carrying out ultrasonic treatment for 1-4 h at the ultrasonic frequency of 40-60 kHz to obtain the MXene nanosheet dispersion.
By adopting the technical scheme, the concentration and the etching temperature of the hydrofluoric acid solution are controlled, so that the MAX phase material can fully remove the Al layer, and the MXene phase material cannot be over-etched; the size of the MXene nanosheets is moderate by controlling the ultrasonic frequency and the ultrasonic time.
Optionally, in the step of preparing the MXene nanosheet dispersion liquid, the MXene nanosheet comprises Ti3C2Tx、 Ti2CTx、V2CTx、Mo2CTx、Nb2CTx、Nb4C3Tx、Mo2TiC2TxAnd Mo2Ti2C3TxAt least one of (1).
Optionally, in the preparation step of the composite slurry, the weight ratio of the MXene nanosheets to the graphene oxide is (15-20): 5-6.
By adopting the technical scheme, the weight ratio of the MXene nanosheets to the graphene oxide is controlled, so that the viscosity of the composite slurry is moderate, contact sites of the composite membrane are increased in the cross-linking forming process, the hole rate and the number of heat conducting passages are increased, and the heat conducting effect and the wave absorbing performance of the composite membrane are further improved.
Optionally, in the preparation step of the composite slurry, the ultrasonic frequency of ultrasonic dispersion is 50-60 kHz, and the ultrasonic time is 1-2 hours.
By adopting the technical scheme, under the ultrasonic frequency and the ultrasonic time, the graphene oxide sheet layer can be fully intercalated between the MXene nano sheet layers.
Optionally, in the step of preparing the composite slurry, isopropanolamine is added into the graphene oxide solution, and the concentration of the isopropanolamine in the graphene oxide solution is 0.05-0.5 g/L.
By adopting the technical scheme, the surface of the graphene oxide is modified by isopropanolamine, and the isopropanolamine is grafted on the surface of the graphene oxide, so that the polarity of the surface of the graphene oxide can be increased, the modified graphene oxide and MXene nanosheets and modified graphene oxide lamella layers are easy to combine tightly, the number of heat conducting passages and holes in the film is increased, and the heat conducting property and the wave absorbing property of the composite film are further improved; secondly, the isopropanolamine is a good surfactant, so that the film is easy to peel off from the substrate, and the possibility of damaging the film is reduced; and finally, the isopropanolamine is carbonized in the graphitization treatment process, carbon particles are formed between the sheet layers of the composite membrane, a better supporting effect is achieved, the structural stability of the composite membrane is improved, meanwhile, the pore structure inside the composite membrane is increased, and the wave absorbing performance of the composite membrane is improved.
Optionally, in the step of preparing the composite slurry, the size of the sheet diameter of the graphene oxide in the graphene oxide slurry is 0.5-5 μm.
By adopting the technical scheme, the film-forming performance of the graphene oxide is excellent, the diameter of the graphene oxide sheet is controlled within a proper range, and the MXene nanosheets can be fully and firmly attached to the graphene oxide sheet layer, so that the heat-conducting performance and the wave-absorbing performance of the composite film are optimized.
In a second aspect, the present application provides a heat-conducting wave-absorbing composite film, which adopts the following technical scheme: a heat-conducting wave-absorbing composite film is prepared by the preparation method of the heat-conducting wave-absorbing composite film.
By adopting the technical scheme, the prepared heat-conducting wave-absorbing composite membrane has better heat-conducting property and wave-absorbing property, and active groups on the surface are removed in the graphitization treatment step, so that the composite membrane has better oxygen resistance, good stability and longer service life.
Preferably, the thickness of the heat-conducting wave-absorbing composite film is 10 um-700 um.
Through adopting above-mentioned technical scheme, the heat conduction is inhaled the ripples complex film and is accomplished lightweight development, and more specifically, the thickness of heat conduction is inhaled the ripples complex film and can be adjusted according to actual demand in this thickness range.
In summary, the present application has the following beneficial effects:
1. according to the preparation method, graphene oxide and MXene nanosheets are compounded, the MXene nanosheets are attached to graphene oxide sheet layers, the graphene oxide sheet layers are subjected to hydrogen bond action and pi-pi interaction in an sp2 area, so that the MXene nanosheets form a porous film along with the graphene oxide sheet layers, and the defects on the film are repaired through graphitization treatment subsequently, so that the pores on the film are uniformly distributed, the pore diameter is reduced, and the good wave-absorbing and heat-conducting performance is achieved.
2. The film is preferably treated by adopting 2500-3000 ℃ high temperature in the application, so that the pores inside the composite film can be obviously improved, and the composite film is not easy to ablate within the temperature range.
3. In the application, isopropanolamine is preferentially selected to modify graphene oxide to obtain modified graphene oxide, and the internal structure of the film is compact due to the modified graphene oxide, so that the film is further developed towards a light weight direction; meanwhile, the composite membrane is beneficial to forming carbon particles in the graphitization process, stably supports the lamellar structure in the composite membrane, forms a large number of micropores and further improves the wave-absorbing performance of the composite membrane.
Detailed Description
Unless otherwise specified, the raw materials in the examples and comparative examples are as follows:
graphene oxide slurries were purchased from Nanjing Xiancheng nanotechnology Co. The cargo numbers and corresponding dimensions are shown in table 1 below.
TABLE 1 graphene oxide dispersions
Model number
| Sheet diameter
| Concentration of
|
XF020-100675
| 50-200nm
| 0.5mg/mL
|
XF020-100681
| 50-200nm
| 2mg/mL
|
XF020-100691
| 50-200nm
| 1mg/mL
|
XF020-100056
| 0.5-5μm
| 0.5mg/mL
|
XF020-100062
| 0.5-5μm
| 2mg/mL
|
XF020-100653
| 0.5-5μm
| 1mg/mL |
Examples
Example 1
A heat-conducting wave-absorbing composite film is prepared according to the following steps:
preparing MXene nanosheet dispersion liquid:
20g of MAX phase material Ti3AlC2Adding into 100g hydrofluoric acid solution (which is commercially available product, diluted to concentration of 20 wt%), gradually heating to 60 deg.C at 5 deg.C/min, stirring at 400rpm for 10 hr to obtain organ-like MXene phase Ti3C2TxA material;
accordion shape MXene phase Ti3C2TxTransferring the material into deionized water, and repeatedly washing for 3 times;
0.03g of accordion-like MXene phase Ti is taken3C2TxPutting the material into 1L of deionized water, placing the material in ultrasonic dispersion equipment, setting the ultrasonic frequency to be 40kHz, and carrying out ultrasonic treatment for 4 hours to obtain MXene nanosheet dispersion liquid for later use;
preparing composite slurry:
taking 200mL of 0.03g/LMXene nanosheet dispersion liquid, adding the MXene nanosheet dispersion liquid into 360mL of graphene oxide slurry (the model of the graphene oxide slurry is XF020-100675), stirring at the rotating speed of 600rpm for 1h, placing in ultrasonic dispersion equipment, setting the ultrasonic frequency to be 50kHz, and carrying out ultrasonic treatment for 1h to obtain composite slurry;
preparing a film:
transferring the composite slurry into a precise coating machine, coating the composite slurry on a substrate, heating to 100 ℃ at the speed of 5 ℃/min, and keeping the temperature and drying for 2 hours to obtain a film;
and (3) post-treatment:
feeding the film into a graphitization furnace, heating the graphitization furnace to 2300 ℃, carrying out heat preservation treatment for 2h, and introducing argon gas into the graphitization furnace as a protective gas in the graphitization treatment process to obtain a flexible compressible film;
and putting the flexible compressible film into a three-roll calender, and calendering until the thickness of the heat-conducting wave-absorbing composite film is 50 microns.
Examples 2 to 4
A heat-conducting wave-absorbing composite film is different from the composite film in the embodiment 1 in that: the process parameters in the post-treatment step were different, and the specific process parameters are shown in table 2 below.
TABLE 2 Process parameters in the post-treatment step of the thermally conductive wave-absorbing composite film
Examples
| Graphitization temperature/. degree.C
| Heat-insulating treatment time/h
|
Example 1
| 2300
| 2
|
Example 2
| 2500
| 1
|
Example 3
| 2800
| 0.5
|
Example 4
| 3000
| 0.5 |
Examples 5 to 12
A heat-conducting wave-absorbing composite film is different from the composite film in the embodiment 4 in that: the process parameters of the preparation steps of the composite slurry are different, and the specific process parameters are shown in the following table 3.
TABLE 3 Process parameters of the preparation step of the heat-conducting wave-absorbing composite film composite slurry
Examples
| Example 4
| Example 5
| Example 6
| Example 7
| Example 8
|
MXene nanometer sheet dispersion concentration/(g/L)
| 0.03
| 0.03
| 0.03
| 0.03
| 0.1
|
MXene nanosheet dispersion volume/mL
| 200
| 2000
| 1000
| 1200
| 360
|
MXene nanosheet weight/g
| 0.006
| 0.06
| 0.03
| 0.036
| 0.036
|
Graphene oxide slurry concentration/(g/L)
| 0.5
| 0.5
| 0.5
| 0.5
| 0.5
|
Graphene oxide slurry volume/mL
| 360
| 60
| 240
| 180
| 180
|
Graphene oxide weight/g
| 0.18
| 0.03
| 0.12
| 0.09
| 0.09
|
Ultrasonic dispersion frequency/kHz
| 50
| 50
| 50
| 50
| 50
|
Ultrasonic dispersion time/h
| 2
| 2
| 2
| 2
| 2
|
Examples
| Example 9
| Example 10
| Example 11
| Example 12
| |
MXene nanometer sheet dispersion concentration/(g/L)
| 0.15
| 0.15
| 0.15
| 0.15
| |
MXene nanosheet dispersion volume/mL
| 240
| 240
| 240
| 240
| |
MXene nanosheet weight/g
| 0.036
| 0.036
| 0.036
| 0.036
| |
Graphene oxide slurry concentration/(g/L)
| 0.5
| 2
| 1
| 1
| |
Graphene oxide slurry volume/mL
| 180
| 45
| 90
| 90
| |
Graphene oxide weight/g
| 0.09
| 0.09
| 0.09
| 0.09
| |
Ultrasonic dispersion frequency/kHz
| 50
| 50
| 50
| 60
| |
Ultrasonic dispersion time/h
| 2
| 2
| 2
| 1
| |
Example 13
A heat-conducting wave-absorbing composite film, which is different from the composite film in example 11 in that: the graphene oxide slurry with the model of XF020-100653 (the plate diameter is 0.5-5 mu m, and the concentration is 1mg/mL) is replaced by the graphene oxide slurry with the model of XF020-100691 (the plate diameter is 50-200nm, and the concentration is 1mg/mL) in the same volume.
Examples 14 to 16
A heat-conducting wave-absorbing composite film, which is different from the composite film in example 13 in that: before the preparation of the composite slurry, firstly, preprocessing the commercially available graphene oxide slurry, and specifically, operating the following steps:
adding isopropanolamine into the graphene oxide slurry, shaking for 1min, placing in ultrasonic dispersion equipment, setting ultrasonic frequency to be 5kHz, and carrying out ultrasonic treatment for 10min to obtain modified graphene oxide slurry;
in example 14, 0.05g of isopropanolamine is added to 1L of graphene oxide slurry, the obtained modified graphene oxide slurry replaces the graphene oxide slurry with the same volume, and the modified graphene oxide slurry is added to the MXene nanosheet dispersion liquid;
in embodiment 15, 0.2g of isopropanolamine is added into 1L of graphene oxide slurry, the obtained modified graphene oxide slurry replaces the graphene oxide slurry with the same volume, and the modified graphene oxide slurry is added into MXene nanosheet dispersion liquid;
in example 16, 0.5g of isopropanolamine is added to 1L of graphene oxide slurry, the obtained modified graphene oxide slurry replaces the graphene oxide slurry with the same volume, and the modified graphene oxide slurry is added to the MXene nanosheet dispersion.
Example 16
A heat-conducting wave-absorbing composite film, which is different from the composite film in example 15 in that: the preparation steps of the MXene nanosheet dispersion have different specific process parameters, and the specific process operation is as follows:
20g of MAX phase material Ti3AlC2Adding into 333g hydrofluoric acid solution (which is commercially available product and diluted to 30 wt%), gradually heating to 80 deg.C at 5 deg.C/min, stirring at 400rpm for 5h to obtain organ-like MXene phase Ti3C2TxA material;
accordion shape MXene phase Ti3C2TxTransferring the material into deionized water, and repeatedly washing for 3 times;
0.05g of accordion-like MXene phase Ti is taken3C2TxThe material is put into 1L of deionized water, placed in ultrasonic dispersion equipment, set the ultrasonic frequency at 40kHz, and subjected to ultrasonic treatment for 4 hours to obtain MXene nanosheet dispersion liquid.
Comparative example
Comparative example 1
A pure MXene film prepared by the following steps:
preparing MXene nanosheet dispersion liquid:
adding 20g of MAX phase material Ti3AlC2 into 100g of hydrofluoric acid solution (the hydrofluoric acid solution is a commercially available product and is diluted to the concentration of 20 wt%), gradually heating to 60 ℃ at the speed of 5 ℃/min, controlling the stirring speed to be 400rpm, and stirring for 10h to obtain an organ-shaped MXene phase Ti3C2Tx material;
transferring the organ-shaped MXene phase Ti3C2Tx material into deionized water, and repeatedly washing for 3 times;
0.03g of accordion-like MXene phase Ti is taken3C2TxPutting the material into 1L of deionized water, placing the material in ultrasonic dispersion equipment, setting the ultrasonic frequency to be 40kHz, and carrying out ultrasonic treatment for 4 hours to obtain MXene nanosheet dispersion liquid;
transferring the MXene nanosheet dispersion liquid into a precision coating machine, coating the MXene nanosheet dispersion liquid on a substrate, heating to 100 ℃ at the speed of 5 ℃/min, and keeping the temperature and drying for 2 hours to obtain a film;
feeding the film into a graphitization furnace, heating the graphitization furnace to 2300 ℃, carrying out heat preservation treatment for 2h, and introducing argon gas into the graphitization furnace as a protective gas in the graphitization treatment process to obtain a flexible compressible film;
and putting the flexible compressible film into a three-roll calender, and calendering until the thickness of the heat-conducting wave-absorbing composite film is 50 microns.
Comparative example 2
A pure graphene film is prepared by taking 360mL of graphene oxide slurry, transferring the graphene oxide slurry to a precise coating machine, coating the graphene oxide slurry on a substrate, heating to 100 ℃ at the speed of 5 ℃/min, and preserving heat and drying for 2h to obtain the film;
feeding the film into a graphitization furnace, heating the graphitization furnace to 2300 ℃, carrying out heat preservation treatment for 2h, and introducing argon gas into the graphitization furnace as a protective gas in the graphitization treatment process to obtain a flexible compressible film;
and putting the flexible compressible film into a three-roll calender, and calendering until the thickness of the heat-conducting wave-absorbing composite film is 50 microns.
Comparative example 3
A film is different from the film obtained in example 1 in that in the post-treatment step, the film is fed into a graphitization furnace, the temperature in the graphitization furnace is raised to 1000 ℃, and the heat preservation treatment is carried out for 3 hours.
Performance test
The thermal conductivity test and the electromagnetic shielding test were performed on the above examples 1 to 17 and comparative examples 1 to 3 while controlling the thickness of each of examples 1 to 17 and comparative examples 1 to 3 to 50 + -0.5 μm.
Testing the thermal conductivity of the film according to ASTM E1461;
the films were tested for shielding effectiveness and shielding band according to ASTM ES-7; the shielding effectiveness is more than or equal to 40dB in the shielding wave band.
The result of the detection
TABLE 4 measurement results of thermal conductivity of examples 1 to 17 and comparative examples 1 to 3
TABLE 5 results of electromagnetic shield test for examples 1-17 and comparative examples 1-3
Note: the larger the maximum electromagnetic shielding efficiency is, the larger the range of the shielding wave band is, and the better the wave absorbing performance is proved.
As can be seen from the combination of comparative examples 1 to 3 and example 1 and the combination of tables 4 to 5, the composite film prepared by combining graphene and MXene nanosheets through specific graphitization treatment in example 1 has a synergistic effect in the aspect of improving the thermal conductivity, and the thermal conductivity is higher than that of a pure graphene film (comparative example 2) and a pure MXene film (comparative example 1);
in the aspect of wave absorbing performance, the maximum value of the electromagnetic shielding effectiveness of the embodiment 1 is smaller than that of a pure MXene film, but the range of the electromagnetic shielding wave band is far larger than that of the pure MXene film; the reason for this may be: the structural defects of the embodiment 1 are repaired in the graphitization treatment process, so that the dielectric property of the composite membrane is improved, and electromagnetic waves easily enter the composite membrane, so that the wave absorbing range of the composite membrane is expanded;
the difference between the embodiment 1 and the comparative example 3 is that the treatment temperature of the film in the post-treatment is different, and the thermal conductivity, the maximum electromagnetic shielding efficiency and the electromagnetic shielding wave band range of the comparative example 3 and the embodiment 1 are all smaller than the detection data of the embodiment 1, which shows that the graphitization treatment of the film is beneficial to improving the thermal conductivity and the wave absorbing performance of the composite film.
It can be seen from the combination of examples 1 to 4 and tables 4 to 5 that the graphitization treatment temperatures and times of examples 1 to 4 are different, and the detection data of the thermal conductivity, the maximum electromagnetic shielding effectiveness and the electromagnetic shielding band range of examples 1 to 4 are all improved remarkably, which indicates that the performance of the composite film is influenced remarkably by controlling the graphitization treatment temperature and time.
Combining examples 4-12 and tables 4-5, it can be seen that the weight ratio of graphene oxide to MXene nanosheet in examples 4-7 is different, and the detection data shows that the ratio of example 7 is a better ratio, which may be due to: in the embodiment 7, the content of graphene oxide is moderate, so that MXene nanosheets can be attached to graphene oxide lamella more, and the film forming effect is good when the graphene oxide film is formed; in examples 7 to 11, the concentrations of the graphene oxide slurry and the MXene nanosheets are changed, and according to detection data, the optimal concentration of the MXene nanosheet dispersion liquid is 0.15g/L, the optimal concentration of the graphene oxide slurry is 1g/L, and the composite film prepared from the slurry prepared under the optimal concentration has the optimal heat conduction and wave absorption properties.
It can be seen from the combination of examples 13 to 16 and tables 4 to 5 that the addition of isopropanolamine in examples 14 to 16 can significantly improve the heat conductivity and the wave absorption of the composite film, which proves that the addition of isopropanolamine is beneficial to forming carbon particles in the composite film during graphitization, stably supports the lamellar structure in the composite film, forms a large number of micropores, and the carbon particles are longitudinally communicated with adjacent lamellar layers in the composite film, so that the heat conductivity of the composite film in all directions is increased, and macroscopically, the heat conductivity is improved.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.