Ink-jet printable wave-absorbing material and preparation method thereof

Abstract

The application belongs to the technical field of microwave absorption, and relates to a wave-absorbing material capable of being inkjet printed and a preparation method thereof. The wave-absorbing material capable of being inkjet printed comprises MXene nanosheets, two-dimensional inorganic nanosheets, water and ethanol, wherein the mass ratio of the two-dimensional inorganic nanosheets / MXene nanosheets is 1-40%, and the volume ratio of the water / ethanol is 0.2-0.8. The preparation method of the wave-absorbing material comprises the following steps: MXene nanosheets are prepared by placing MXene precursor powder in a mixed solution of concentrated hydrochloric acid and lithium fluoride powder for etching; two-dimensional inorganic nanosheets are prepared by mixing layered oxide ceramic powder with acid solution for ion exchange and then carrying out intercalation reaction; and MXene / two-dimensional inorganic composite nanosheet ink is obtained by uniformly dispersing the two kinds of nanosheets in a water / ethanol mixed solvent. The preparation method has low cost, is simple and convenient to operate, and is environmentally friendly, and can realize large-scale production. The prepared wave-absorbing material has good stability, can be integrated on the surface of various rigid and flexible electronic devices in the form of inkjet printing, and can effectively reduce electromagnetic wave pollution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microwave absorption, and relates to an ink-jet printable wave-absorbing material and a preparation method thereof. BACKGROUND

[0002] With the increasing number of miniature electronic devices and flexible wearable electronic devices, harmful electromagnetic radiation pollution has intensified on a large scale, directly affecting the health of human life and the normal operation of electronic communication equipment. Therefore, there is an urgent need for high-performance wave-absorbing materials to reduce electromagnetic pollution. The complex application environment of new technologies not only requires the new generation of electromagnetic wave-absorbing materials to have the characteristics of light weight, thin thickness, strong absorption and wide absorption, but also needs to have the characteristics of miniaturization, flexibility and easy processing, so as to facilitate the integration with flexible wearable and other electronic devices. Therefore, this poses a great challenge to the design and preparation of microwave-absorbing materials in this field.

[0003] Printed electronics technology, especially mask-free, high-resolution, digital and flexible inkjet printing technology, provides a very promising route. Two-dimensional materials are considered a very promising microwave-absorbing material due to their unique layered morphology, low mass density, excellent processing performance and controllable electromagnetic parameters. In addition, they can be directly prepared into functional ink through solution processing (such as liquid phase exfoliation) in solution, and combined with solution processing technologies including inkjet printing to realize the transfer of two-dimensional materials on various rigid and flexible substrates or object surfaces and the preparation of electronic devices.

[0004] Currently disclosed for the preparation and research of two-dimensional wave-absorbing materials are: Sun Yongqin et al. (Sun Yongqin. BiFeO3 / Ti3C2T x MXene composite material and its wave-absorbing performance[D]. Xi'an University of Technology, 2022.) BiFeO3 and Ti3C2T x are compounded by solvothermal method, which can achieve a wave-absorbing intensity of-50.0dB and a bandwidth of 2.1GHz under the condition of matching thickness of 5.3mm. Gan Wuxiang et al. (Gan Wuxiang. Structure characterization and wave-absorbing performance of Ti3C2T x and Ti3C2T x / Co3O4 composite material[D]. Harbin Institute of Technology, 2022.) prepared Ti3C2T x / Co3O4 composite material, at a filling amount of 50wt% of the wave-absorbing agent, at a frequency of 10GHz, a thickness of 5.5mm, the minimum reflection loss value is-25dB, and the effective wave-absorbing bandwidth is 7GHz. Qin Faxiang et al. (CN 115650286 A) used a dispersion liquid of MXene, graphene oxide (GO) and water as a mother liquor, and prepared rGO / MXene / TiO-2 / Fe-2C multi-level heterostructure porous microspheres by using a spray-freeze drying technology and a microwave irradiation method. Most of the above methods use particles and blocks to modify two-dimensional materials to improve their wave-absorbing performance, but this further leads to high material density and increased mass, thereby limiting the improvement of wave-absorbing performance, and the preparation process is complex, which is difficult to realize large-scale preparation. In addition, the synthesized materials are mostly in the form of solid powders, which are difficult to transfer, that is, integrated with various devices, which further limits the wide application of the materials. SUMMARY

[0005] The purpose of the present application is to overcome the shortcomings of the prior art, and to provide a wave-absorbing material that can be inkjet printed and a preparation method thereof. The wave-absorbing material has good stability, is green and environmentally friendly, and has low cost. It can be integrated on the surface of various rigid and flexible electronic devices by inkjet printing. The printed sample exhibits good microwave absorption performance and can effectively reduce electromagnetic wave pollution.

[0006] The present application is realized by the following way: a wave-absorbing material that can be inkjet printed, comprising MXene nanosheets, two-dimensional inorganic nanosheets, water and ethanol, wherein the mass ratio of two-dimensional inorganic nanosheets / MXene nanosheets is 1-40%, the volume ratio of water / ethanol is 0.2-0.8, and the concentration of MXene / two-dimensional inorganic composite nanosheets is 1-4mg / mL.

[0007] According to the above scheme, the MXene is Ti3C2T x , wherein T x represents functional groups such as -O, -OH and -F; the lateral particle size of the MXene nanosheet is 100-400nm, and the thickness is 1-2nm.

[0008] According to the above scheme, the two-dimensional inorganic nanosheet is at least one of Sr2Nb3O 10 , Ca2Nb3O 10 , Ca2NaNb4O 13 ; the lateral particle size of the two-dimensional inorganic nanosheet is 100-400nm, and the thickness is 1-3nm.

[0009] The preparation method of the above-mentioned wave-absorbing material that can be inkjet printed, characterized by comprising the following steps:

[0010] (1) The MXene precursor powder was placed in a mixed solution of concentrated hydrochloric acid and lithium fluoride powder for etching, and then the acidic substances contained in the solution were removed by centrifugation. After centrifugation, the MXene suspension with a large number of hydrophilic groups on the surface was obtained. The MXene suspension was freeze-dried to remove water and obtain MXene nanosheet powder.

[0011] (2) The layered oxide ceramic powder is mixed with acid solution and stirred to make the reaction complete, replacing K ions with H ions. Then, the hydrated proton phase is obtained by washing, filtering and natural drying. The hydrated proton phase and TBAOH in an equimolar ratio are added to ultrapure water and exfoliated by ultrasonic treatment to obtain a two-dimensional inorganic nanosheet aqueous solution. Then, the two-dimensional inorganic nanosheet powder is obtained by freeze drying.

[0012] (3) The two-dimensional inorganic nanosheets and MXene nanosheets prepared in steps (1) and (2) are added to ultrapure water at a mass ratio of 0.01-0.4 and dispersed evenly to obtain an aqueous solution of nanosheets; the concentration of MXene / two-dimensional inorganic composite nanosheets is 1-4 mg / mL;

[0013] (4) Add ethanol to the nanosheet aqueous solution prepared in step (3) at a water / ethanol volume ratio of 0.2-0.8 and disperse it evenly to obtain MXene / two-dimensional inorganic composite nanosheet ink;

[0014] According to the above scheme, the ultrasonic power of ultrasonic treatment in step (2) is 288-720W and the ultrasonic time is 0.5-4h; the dispersion method in steps (3) and (4) is one or more of magnetic stirring, ultrasonic dispersion and mechanical stirring.

[0015] The MXene / two-dimensional inorganic composite nanosheet ink prepared above is injected into an ink cartridge, and the designed pattern is printed by inkjet printing. The printed MXene / two-dimensional inorganic composite nanosheet pattern is then vacuum dried to obtain the MXene / two-dimensional inorganic composite nanosheet microwave absorbing coating.

[0016] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0017] 1. This invention utilizes a composite of two-dimensional inorganic nanosheets and MXene nanosheets to prepare a pure two-dimensional microwave absorbing material, effectively improving the problems of poor impedance matching, weak absorption intensity, and narrow absorption bandwidth of MXene as a microwave absorbing material. Furthermore, this method is low-cost, easy to operate, and suitable for mass production, overcoming the shortcomings of traditional microwave absorbing material production.

[0018] 2. This invention prepares inkjet-printable ink from the synthesized MXene / two-dimensional inorganic composite nanosheet microwave absorbing material. It can be transferred to the surface of any object by inkjet printing, realizing integration with various electronic devices, and overcoming the problems of large volume, high rigidity and difficult transfer of traditional microwave absorbing materials.

[0019] 3. The MXene / two-dimensional inorganic composite nanosheet ink prepared by this invention is composed of common solvents water and ethanol, making it safe, non-toxic, environmentally friendly, inexpensive, and readily available, enabling large-scale production. Furthermore, inkjet printing technology allows for the printing of microwave-absorbing coatings with arbitrary patterns, offering advantages such as maskless operation, digitalization, and flexibility, and is more environmentally friendly than techniques like blade coating and photolithography. Moreover, the thickness and uniformity of inkjet-printed MXene / two-dimensional inorganic composite nanosheet films are controllable, offering significant advantages in the field of printed electronics. Attached Figure Description

[0020] Figure 1 It is (a)Ti3C2T in Embodiment 1 of the present invention x and (b)Sr2Nb3O 10 Atomic force microscopy (AFM) image of nanosheets;

[0021] Figure 2 It is (a)Ti3C2T in embodiments 1, 2 and 3 of the present invention. x / Sr2Nb3O 10 (b)Ti3C2T x / Ca2Nb3O 10 and (c)Ti3C2T x / Ca2NaNb4O 13 Composite ink diagram;

[0022] Figure 3 It is Ti3C2T in Embodiment 1 of the present invention x / Sr2Nb3O 10 Patterns printed with composite inks by inkjet printing. Detailed Implementation

[0023] The following are three preferred embodiments of the present invention, but the present invention is not limited thereto.

[0024] Example 1:

[0025] An inkjet-printable microwave absorbing material, comprising Ti3C2T x Nanosheets, Sr2Nb3O 10 Nanosheets, water, and ethanol; wherein Sr2Nb3O 10 Nanosheets / Ti3C2T x The nanosheets have a mass ratio of 5 / 95, the water / ethanol volume ratio is 1 / 2, and the Ti3C2T...x / Sr2Nb3O 10 The concentration of the composite nanosheets was 2 mg / mL.

[0026] The aforementioned inkjet-printable microwave absorbing material is specifically prepared using the following method:

[0027] (1) 1.0 g of precursor powder Ti3AlC2 was placed in a mixed solution of 20 mL of 9 mol / L concentrated hydrochloric acid and 1.98 g of lithium fluoride powder for etching. The acidic substances in the solution were removed by centrifugation, and then centrifugation was continued to obtain Ti3C2T with a large number of hydrophilic groups on the surface. x The resulting Ti3C2T nanosheet aqueous dispersion was prepared. x Ti3C2T was obtained by freeze-drying to remove moisture from the suspension. x powder;

[0028] (2) 2.5g of KSr2Nb3O obtained by high-temperature sintering 10 Layered ceramic powder was added to 100 mL of a 5 mol / L nitric acid aqueous solution. The reaction was carried out by stirring to ensure complete reaction, replacing K ions with H ions. After washing, filtration and natural drying, HSR2Nb3O was obtained. 10 nH2O layered ceramic powder. Equimolar ratio of HSR2Nb3O 10 ·nH2O and TBAOH were added to ultrapure water, and the mixed solution was sonicated at 300W for 0.5h to obtain Sr2Nb3O. 10 The nanosheet aqueous dispersion, the obtained Sr2Nb3O 10 Sr2Nb3O was obtained by freeze-drying an aqueous dispersion of nanosheets to remove water. 10 powder;

[0029] (3) Take the Ti3C2T obtained in steps (1) and (2) x and Sr2Nb3O 10 Nanosheet powder was added to a mixed solvent with a water / ethanol volume ratio of 1 / 2 at a mass ratio of 95 / 5. The mixture was stirred at 500 r / min for 12 h to obtain Ti3C2T. x / Sr2Nb3O 10 Composite inks;

[0030] (4) The Ti3C2T obtained in step (3) x / Sr2Nb3O 10 Composite ink is injected into the ink cartridge, and the designed pattern is printed on the photo paper substrate under the conditions of inkjet voltage of 22V, inkjet frequency of 1000Hz, droplet spacing of 25μm, nozzle diameter of 20μm, and substrate temperature of 50℃.

[0031] (5) Print the Ti3C2T inkjet printed on the photo paper in step (4). x / Sr2Nb3O 10 The composite membrane was placed in a vacuum drying oven and dried for 12 hours under a vacuum of 0.1 Pa and a temperature of 60 °C.

[0032] For Ti3C2T x / Sr2Nb3O 10 Microwave absorption tests were conducted on the composite material, and the maximum reflection loss was measured to be -47.4 dB, with an effective bandwidth greater than 4 GHz.

[0033] Example 2:

[0034] An inkjet-printable microwave absorbing material, comprising Ti3C2T x Nanosheets, Ca2Nb3O 10 Nanosheets, water, and ethanol; among which Ti3C2T x Nanosheets / Ca2Nb3O 10 The nanosheets have a mass ratio of 90 / 10, and the water / ethanol volume ratio is 1 / 2. (Ti3C2T) x / Ca2Nb3O 10 The concentration of the composite nanosheets was 2 mg / mL.

[0035] Except for step (2) KSr2Nb3O in the preparation method 10 Layered ceramic powder was replaced with KCa2Nb3O 10 The layered ceramic powder, except that the mass ratio in step (3) is changed to 90 / 10, is the same as the steps in Example 1.

[0036] For Ti3C2T x / Ca2Nb3O 10 The composite material underwent microwave absorption testing, and the maximum reflection loss was measured to be -45.5 dB, with an effective bandwidth of 3.9 GHz.

[0037] Example 3:

[0038] An inkjet-printable microwave absorbing material, comprising Ti3C2T x Nanosheets, Ca2NaNb4O 13 Nanosheets, water, and ethanol; among which Ti3C2T x Nanosheets / Ca2NaNb4O 13 The nanosheets have a mass ratio of 85 / 15, the water / ethanol volume ratio is 1 / 2, and the Ti3C2T... x / Ca2NaNb4O 13 The concentration of the composite nanosheets was 2 mg / mL.

[0039] Except for step (2) KSr2Nb3O in the preparation method10 The layered ceramic powder was replaced with KCa2NaNb4O 13 The layered ceramic powder, except that the mass ratio in step (3) is changed to 85 / 15, is the same as the steps in Example 1.

[0040] For Ti3C2T x / Ca2NaNb4O 13 The composite material underwent microwave absorption testing, and the maximum reflection loss was measured to be -49.5 dB, with an effective bandwidth of 4.2 GHz.

[0041] The above embodiments are only used to illustrate and not limit the technical solutions of the present invention. Although the above embodiments have described the present invention in detail, those skilled in the art should understand that modifications or equivalent substitutions can be made to the present invention, but any modifications and partial substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. An inkjet-printable microwave absorbing material, comprising MXene nanosheets, two-dimensional inorganic nanosheets, water, and ethanol; characterized in that... The mass ratio of two-dimensional inorganic nanosheets to MXene nanosheets is 1-40%, the volume ratio of water to ethanol is 0.2-0.8, and the concentration of MXene / two-dimensional inorganic composite nanosheets is 1-4 mg / mL; MXene is Ti3C2T. x T x Representing −O, −OH, and −F functional groups; MXene nanosheets have a lateral particle size of 100-400 nm and a thickness of 1-2 nm; the two-dimensional inorganic nanosheets are Sr₂Nb₃O 10 Ca2Nb3O 10 Ca2NaNb4O 13 At least one of the following; the two-dimensional inorganic nanosheets have a lateral particle size of 100-400 nm and a thickness of 1-3 nm.

2. The method for preparing an inkjet-printable microwave absorbing material according to claim 1, characterized in that: Including the following implementations step: (1) The MXene precursor powder was placed in a mixed solution of concentrated hydrochloric acid and lithium fluoride powder for etching, and then the acidic substances contained in the solution were removed by centrifugation. After centrifugation, the MXene suspension with a large number of hydrophilic groups on the surface was obtained. The MXene suspension was freeze-dried to remove water and obtain MXene powder. (2) The layered oxide ceramic powder is mixed with acid solution and stirred to make the reaction fully, so that K ions are replaced with H ions. Then, the hydrated proton phase is obtained by washing, filtering and natural drying. The hydrated proton phase and TBAOH in an equimolar ratio are added to ultrapure water and the two-dimensional inorganic nanosheet aqueous solution is obtained by ultrasonic treatment and peeling. Then, the two-dimensional inorganic nanosheet powder is obtained by freeze drying. (3) The two-dimensional inorganic nanosheets and MXene nanosheets prepared in steps (1) and (2) are added to ultrapure water at a mass ratio of 0.01-0.4 and dispersed evenly to obtain an aqueous solution of nanosheets; the concentration of MXene / two-dimensional inorganic composite nanosheets is 1-4 mg / mL; (4) Add ethanol to the aqueous solution of nanosheets prepared in step (3) at a water / ethanol volume ratio of 0.2-0.8 and disperse it evenly to obtain MXene / two-dimensional inorganic composite nanosheet ink.

3. The method for preparing an inkjet-printable microwave absorbing material according to claim 2, characterized in that: In step (2), the ultrasonic power of the ultrasonic treatment is 288-720 W and the ultrasonic time is 0.5-4 h; the dispersion methods in steps (3) and (4) are one or more of magnetic stirring, ultrasonic dispersion and mechanical stirring.

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