Preparation method of a chiral polyaniline / biomass carbon composite wave-absorbing material

Abstract

The application discloses a preparation method of a bichiral polyaniline / biomass carbon composite wave-absorbing material. Biomass with natural helical structure chiral characteristics is subjected to high-temperature carbonization activation treatment to obtain a micron-level chiral biomass carbon precursor. Aniline monomers are in-situ oxidatively polymerized on the surface of the chiral biomass carbon precursor under the joint action of chiral complexing inducers and initiators to obtain nanometer-level polyaniline with chiral characteristics, namely the bichiral polyaniline / biomass carbon composite wave-absorbing material. The preparation process is simple, controllable and green. The composite wave-absorbing material has the double chiral characteristics of the micron-level chiral biomass carbon precursor and the nanometer-level chiral polyaniline and the synergistic effect of the complex three-dimensional conductive network structure formed by the chiral biomass carbon precursors supporting each other, and thus the wave-absorbing performance of the composite wave-absorbing material is greatly improved. The composite wave-absorbing material can fully meet the increasingly harsh wave-absorbing performance requirements in actual applications and is convenient for industrial promotion.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of composite wave-absorbing materials, in particular to a chiral polyaniline / biomass carbon composite wave-absorbing material and a preparation method thereof. BACKGROUND

[0002] Electromagnetic radiation pollution caused by the rapid development and wide application of information technology has become one of the important problems to be solved. High-performance electromagnetic wave-absorbing materials can convert the incident electromagnetic energy into heat energy or other forms of energy through dielectric loss and magnetic loss. The existing wave-absorbing materials have the problems of complex synthesis, expensive raw materials, large density, single structure, poor loss capacity and the like.

[0003] Chinese patent 201910052035.2 (CN109666451B) discloses a method for preparing a wave-absorbing material by using a biomass carbon source. The method selects rice husk as the carbon source, and prepares a biomass carbon wave-absorbing material by accurately controlling the calcination temperature and reaction time. The method has the characteristics of low cost, no pollution and sustainability, but the wave-absorbing material has the problems of simple structure, single loss mechanism and poor wave-absorbing performance, and it is difficult to meet the increasingly stringent performance requirements in actual applications.

[0004] Chinese patent 202210969543.9 (CN115386337A) discloses a chiral polyaniline / biomass-derived porous carbon composite wave-absorbing material and a preparation method thereof. The method selects biomass such as peanut shell as the carbon source, and prepares the wave-absorbing material by high-temperature carbonization and in-situ oxidative polymerization. The method has the characteristics of simple synthesis process, rich material resources and environmental ecological friendliness, but the wave-absorbing material only has nanoscale polyaniline with chiral characteristics, and the micro-interface of the biomass porous carbon matrix is greatly affected by the porosity, thereby restricting the specific surface area and affecting the effective adhesion of polyaniline. In addition, the composition of the chiral complex inducer used to synthesize polyaniline is complex, and it is difficult to effectively control the gradient.

[0005] Chinese patent 20101010100376.1 (CN101781457B) discloses a molecular sieve assembled chiral polyaniline wave-absorbing material and a preparation method thereof. The specific process is to assemble chiral helical structure polyaniline and ferrite nanoparticles in the channels and surface of the molecular sieve. However, the molecular sieve used in the preparation process is expensive and complex to synthesize, which increases the production cost. The addition of ferrite nanoparticles greatly increases the density of the material to some extent, which is not conducive to the light weight requirement of the wave-absorbing material. SUMMARY

[0006] The application aims to solve the problems of complex chiral complexing agent composition in the preparation of chiral polyaniline / biomass composite wave-absorbing material in the prior art and further improve the wave-absorbing performance of the chiral polyaniline / biomass composite wave-absorbing material, and provides a preparation method of a double-chiral polyaniline / biomass carbon composite wave-absorbing material.

[0007] To solve the above technical problems, the technical scheme adopted by the application is as follows: a preparation method of a double-chiral polyaniline / biomass carbon composite wave-absorbing material, and the specific steps are as follows:

[0008] S1: clean biomass is obtained by cleaning, impurity removal, soaking, filtering and drying of biomass with natural helical structure and chiral characteristics, and is ready for use;

[0009] The soaking solution is a 0.5-2 mol / L KHCO3 solution, and the soaking time is 3-12 h, which is used for subsequent high-temperature carbonization activation.

[0010] S2: the clean biomass obtained in S1 is subjected to high-temperature carbonization activation under vacuum or inert atmosphere, and is naturally cooled to room temperature after calcination, to obtain a chiral biomass carbon precursor, which is ready for use;

[0011] The high-temperature carbonization activation process is as follows: the temperature is raised to 1100-1200℃ at a temperature raising rate of 15-25℃ / min, and the temperature is maintained for 30-60 min.

[0012] S3: the chiral biomass carbon precursor prepared in S2 is immersed in an aqueous solution of aniline monomer and chiral complexing agent, and is subjected to sufficient stirring and ultrasonic oscillation, and then is cooled in an ice water bath.

[0013] The mass ratio of the chiral biomass carbon precursor to the aniline monomer is 5:1-1:5, and the molar ratio of the aniline monomer to the chiral complexing agent is 1:1-1:4.

[0014] S4: the initiator is dissolved in deionized water, and is added dropwise to the suspension liquid prepared in S3, and is then subjected to standing, filtering, washing and freeze-drying, to obtain a double-chiral polyaniline / biomass carbon composite wave-absorbing material.

[0015] The molar ratio of the initiator to the aniline monomer is 2:1-1:4.

[0016] As a further optimization of the preparation method of the double-chiral polyaniline / biomass carbon composite wave-absorbing material, the high-temperature carbonization activation process is further optimized as follows: the temperature is raised to 1100-1200℃ at a temperature raising rate of 20-25℃ / min, and the temperature is maintained for 30-45 min.

[0017] As a further optimization of the preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material of the application: the biomass with natural helical structure chiral characteristics is a fluffy fruit cluster or a stem tendril.

[0018] As a further optimization of the preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material of the application: the biomass with natural helical structure chiral characteristics is a fluffy fruit cluster or a stem tendril.

[0019] As a further optimization of the preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material of the application: the chiral compound inducer in step S3 is a mixture of camphor sulfonic acid and mandelic acid in a mass ratio of 6:1-5:1.

[0020] As a further optimization of the preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material of the application: the mass ratio of the chiral biomass carbon precursor to the aniline monomer in step S3 is 2:1-1:2.

[0021] As a further optimization of the preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material of the application: the mass ratio of the chiral biomass carbon precursor to the aniline monomer in step S3 is 2:1-1:2.

[0022] As a further optimization of the preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material of the application: the dropping speed of the initiator aqueous solution in step S4 is 1-8 ml / min, and the dropping is carried out under a stirring speed of 50-500 r / min, and after the dropping is completed, the reaction is further carried out for 2-20 h.

[0023] A chiral polyaniline / biomass carbon composite wave-absorbing material prepared by the above preparation method.

[0024] The application has the following beneficial effects:

[0025] Firstly, the preparation process of the application is simple, controllable, green and environmentally friendly, and the prepared composite wave-absorbing material has a synergistic effect of the dual chiral characteristics of the micron-level chiral biomass carbon precursor and the nanometer-level chiral polyaniline and the complex three-dimensional conductive network structure formed by the chiral biomass carbon precursors supporting each other, which exhibits multiple loss mechanisms, and the wave-absorbing performance is further greatly improved, fully meeting the increasingly demanding wave-absorbing performance requirements in actual applications, and being convenient for industrialization promotion.

[0026] Secondly, the biomass material with chiral characteristics of natural helical structure is carbonized and activated under specific conditions, and the biomass carbon after carbonization and activation perfectly inherits the chiral characteristics, specifically, the applicant finds that fast heating to a high carbonization temperature at a high heating rate can sufficiently reduce the reactivity of the biomass and reduce the burnout rate in a low-temperature environment, so that the biomass after carbonization and activation can perfectly inherit the chiral characteristics.

[0027] Thirdly, the aniline monomers in the composite wave-absorbing material of the application are oxidized and polymerized into superhelical structures with chiral characteristics under the action of a chiral inducer, all of which exhibit special optical rotation and circular dichroism, and produce cross-polarization coupling effect under the action of an alternating electromagnetic field, thereby endowing the composite wave-absorbing material with multiple electromagnetic wave loss mechanisms. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 SEM image of the composite wave-absorbing material prepared in Example 1;

[0029] Figure 2 Fourier infrared spectrum of the composite wave-absorbing material prepared in Example 1;

[0030] Figure 3 Raman spectrum of the composite wave-absorbing material prepared in Example 1. DETAILED DESCRIPTION

[0031] In order to better understand the application, the content of the application will be further illustrated below in combination with examples, but the content of the application is not limited to the following examples.

[0032] Preparation method of the composite wave-absorbing material

[0033] The chiral material can exhibit special optical rotation and circular dichroism due to its unique superhelical structure, and produce cross-polarization coupling effect under the action of an alternating electromagnetic field, which can effectively improve the electromagnetic wave absorption efficiency and broaden the absorption frequency band. The biomass with chiral characteristics of natural helical structure widely exists in nature, and aniline can be oxidized and polymerized to form superhelical structures with chiral characteristics under the action of a chiral inducer, and the chiral characteristics can endow both of them with multiple electromagnetic wave loss mechanisms.

[0034] The biomass carbon is a potential candidate for synthesizing carbon-based composite wave-absorbing materials, which is not only rich in resources, simple to prepare and environmentally friendly, but also has a high specific surface area, which can provide abundant sites for in-situ growth of polyaniline, thereby promoting the construction of heterogeneous interfaces of the composite material and the improvement of interface polarization. Therefore, the aniline monomers are in-situ oxidized and polymerized on the surface of the chiral biomass carbon to generate polyaniline with chiral characteristics, thereby preparing a double-chiral polyaniline / biomass carbon composite wave-absorbing material, and the synergistic effect of the double-chiral characteristics and multiple electromagnetic wave loss mechanisms enhances the electromagnetic wave absorption performance.

[0035] The application relates to a preparation method of a chiral polyaniline / biomass carbon composite wave-absorbing material.

[0036] S1: clean biomass is obtained by cleaning, impurity removal, soaking, filtering and drying of biomass with a natural helical structure chiral feature, and the clean biomass is prepared for use.

[0037] The biomass with the natural helical structure chiral feature is a fluffy fruit cluster or a stem tendril, for example, a sycamore fruit cluster, a dandelion fruit cluster, a reed fruit cluster, a wheat awn or a corn silk. It should be noted that the above biomass only lists several common biomasses.

[0038] The soaking solution is a 0.5-2 mol / L KHCO3 solution, and the soaking time is 3-12 h, which is used for subsequent high-temperature carbonization activation.

[0039] S2: the clean biomass obtained in S1 is calcined under vacuum or in an inert atmosphere, and is naturally cooled to room temperature after calcination, so that a chiral biomass carbon precursor is obtained and prepared for use.

[0040] The high-temperature carbonization activation process is specifically as follows: the temperature is raised to 1100-1200 DEG C at a temperature raising rate of 15-25 DEG C / min, and the temperature is kept for 30-60 min. More preferably, the high-temperature carbonization activation process is specifically as follows: the temperature is raised to 1100-1200 DEG C at a temperature raising rate of 20-25 DEG C / min, and the temperature is kept for 30-45 min.

[0041] S3: the chiral biomass carbon precursor prepared in S2 is immersed in aniline monomers and a chiral compound inducing agent aqueous solution, is fully stirred and ultrasonically vibrated, and is then cooled in an ice water bath.

[0042] The chiral compound inducing agent is a mixture of camphor sulfonic acid and mandelic acid with a mass ratio of 10:1-2:1. The mass ratio of the chiral biomass carbon precursor to the aniline monomers is 5:1-1:5. The mass ratio of the aniline monomers to the chiral compound inducing agent is 1:1-1:4.

[0043] S4: an initiator is dissolved in deionized water, is added dropwise into the suspension liquid prepared in S3, and is then left to stand, and then the chiral polyaniline / biomass carbon composite wave-absorbing material is prepared through filtering, washing and freeze drying.

[0044] The initiator is ammonium persulfate or ferric chloride, the mass ratio of the initiator to the aniline monomers is 2:1-1:4, the dropping speed of the initiator aqueous solution is 1-8 ml / min, the dropping is carried out under a stirring speed of 50-500 r / min, and the initiator aqueous solution is left to stand for 2-20 h after the dropping is completed.

[0045] <Embodiment 1>

[0046] A preparation method of a chiral polyaniline / biomass carbon composite wave-absorbing material, comprising the following steps:

[0047] S1: After the fruiting branches of the Chinese parasol are stripped, the surface impurities are removed by repeatedly washing with deionized water and ethanol, and then the fruiting branches are soaked in a 0.5 mol / L KHCO3 solution for 6 hours, and then filtered and freeze-dried.

[0048] S2: The fruiting branches treated in S1 are placed in a tube furnace and calcined under the protection of N2, the heating rate in the calcination process is 20℃ / min, the calcination temperature is 1200℃, the holding time is 35 min, and the fruiting branches are naturally cooled to room temperature, so as to obtain a biomass carbon precursor.

[0049] S3: 0.45 ml of aniline monomer, 1.2 g of camphor sulfonic acid and 0.15 g of mandelic acid are fully dissolved in 50 ml of deionized water, 0.4 g of the biomass carbon precursor is weighed and immersed in the above solution, and then a uniform and stable suspension pre-solution is obtained through ultrasonic and stirring, and the suspension pre-solution is cooled to 0℃ through ice water bath cooling.

[0050] S4: 1 g of ammonium persulfate is weighed and fully dissolved in 20 ml of deionized water, and after the ice water bath is cooled to a constant temperature, the suspension liquid in S3 is uniformly added at a speed of 5 ml / min through a constant pressure dropping funnel, the stirring is stopped after the addition is completed, and the reaction is placed in the ice water bath for 24 hours, and then filtered, washed, centrifuged and freeze-dried to obtain a chiral polyaniline / biomass carbon composite wave-absorbing material, and the SEM image of the prepared composite wave-absorbing material is as shown in Figure 1 , the Fourier infrared spectrum is as shown in Figure 2 , and the Raman spectrum is as shown in Figure 3 .

[0051] <Embodiment 2>

[0052] A preparation method of a chiral polyaniline / biomass carbon composite wave-absorbing material, comprising the following steps:

[0053] S1: After the fruiting branches of the Chinese parasol are stripped, the surface impurities are removed by repeatedly washing with deionized water and ethanol, and then the fruiting branches are soaked in a 0.5 mol / L KHCO3 solution for 6 hours, and then filtered and freeze-dried.

[0054] S2: The fruiting branches treated in S1 are placed in a tube furnace and calcined under the protection of N2, the heating rate in the calcination process is 20℃ / min, the calcination temperature is 1200℃, the holding time is 35 min, and the fruiting branches are naturally cooled to room temperature, so as to obtain a biomass carbon precursor.

[0055] S3: 0.4ml aniline monomer, 1g camphor sulfonic acid, 0.2g mandelic acid were dissolved in 50ml deionized water, then 0.5g biomass carbon precursor was weighed and immersed in the above solution, and a uniform and stable suspension solution was obtained by ultrasonic stirring, and then cooled to 0℃ in an ice water bath.

[0056] S4: 0.8g ammonium persulfate was weighed and dissolved in 20ml deionized water, and then cooled to constant temperature in an ice water bath. After that, it was added to the suspension solution in S3 at a constant speed of 5ml / min through a constant pressure dropping funnel, and stirred at 200r / min during the dropping process. After the dropping was completed, the stirring was stopped and the reaction was placed in an ice water bath for 24 hours. Then, the product was filtered, washed, centrifuged, and freeze-dried to obtain the double-chiral polyaniline / biomass carbon composite wave-absorbing material.

[0057] <Example 3>

[0058] A preparation method of a double-chiral polyaniline / biomass carbon composite wave-absorbing material, comprising the following steps:

[0059] S1: The dandelion fruiting heads were repeatedly cleaned with deionized water and ethanol to remove surface impurities, then soaked in a 0.5mol / L KHCO3 solution for 12h, and then filtered and freeze-dried.

[0060] S2: The treated dandelion fruiting heads in S1 were placed in a tube furnace and calcined under N2 atmosphere. The heating rate was 15℃ / min, the calcination temperature was 1150℃, and the holding time was 50min. After natural cooling to room temperature, the product was ground to obtain the biomass carbon precursor.

[0061] S3: 0.45ml aniline monomer, 1.2g camphor sulfonic acid, 0.15g mandelic acid were dissolved in 50ml deionized water, then 0.4g biomass carbon precursor was weighed and immersed in the above solution, and a uniform and stable suspension solution was obtained by ultrasonic stirring, and then cooled to 0℃ in an ice water bath.

[0062] S4: 1g ammonium persulfate was weighed and dissolved in 20ml deionized water, and then cooled to constant temperature in an ice water bath. After that, it was added to the suspension solution in S3 at a constant speed of 5ml / min through a constant pressure dropping funnel, and stirred at 200r / min during the dropping process. After the dropping was completed, the stirring was stopped and the reaction was placed in an ice water bath for 24 hours. Then, the product was filtered, washed, centrifuged, and freeze-dried to obtain the double-chiral polyaniline / biomass carbon composite wave-absorbing material.

[0063] <Example 4>

[0064] A preparation method of a double-chiral polyaniline / biomass carbon composite wave-absorbing material, comprising the following steps:

[0065] S1: The surface impurities of the dandelion fruiting heads were removed by repeatedly washing with deionized water and ethanol, and then the dandelion fruiting heads were soaked in a 1 mol / L KHCO3 solution for 12 h, filtered, and dried.

[0066] S2: The dandelion fruiting heads treated in S1 were placed in a tube furnace and calcined under vacuum conditions, the heating rate during calcination was 22℃ / min, the calcination temperature was 1200℃, the holding time was 30 min, and the biomass carbon precursor was prepared by grinding after natural cooling to room temperature.

[0067] S3: 0.4 ml of aniline monomer, 1 g of camphor sulfonic acid, and 0.2 g of mandelic acid were fully dissolved in 50 ml of deionized water, 0.5 g of the biomass carbon precursor was weighed and immersed in the above solution, and a uniform and stable suspension was obtained by ultrasonic and stirring, and then the suspension was cooled to 0℃ in an ice water bath.

[0068] S4: 0.8 g of ammonium persulfate was weighed and fully dissolved in 20 ml of deionized water, and after cooling to a constant temperature in an ice water bath, it was uniformly added to the suspension in S3 at a speed of 5 ml / min through a constant pressure dropping funnel, and stirred at 200 r / min during the addition process, and after the addition was completed, the stirring was stopped and the reaction was allowed to stand in an ice water bath for 24 hours, and then the double-chiral polyaniline / biomass carbon composite wave-absorbing material was prepared by filtering, washing, centrifuging, and freeze-drying.

[0069] <Comparative Example 1>

[0070] 1) After the fruiting heads of the phoenix tree were peeled, the surface impurities were removed by repeatedly washing with deionized water and ethanol, and then the fruiting heads were soaked in a 0.5 mol / L KHCO3 solution for 6 h, filtered, and dried.

[0071] 2) The fruiting heads treated in 1) were placed in a tube furnace and calcined under N2 atmosphere protection, the heating rate during calcination was 20℃ / min, the calcination temperature was 1200℃, the holding time was 35 min, and the chiral biomass carbon precursor was prepared by grinding after natural cooling to room temperature.

[0072] <Comparative Example 2>

[0073] 1) 0.45 ml of aniline monomer, 1.2 g of camphor sulfonic acid, and 0.15 g of mandelic acid were fully dissolved in 50 ml of deionized water, and the solution was cooled to 0℃ in an ice water bath.

[0074] 2) 1 g of ammonium persulfate was weighed and fully dissolved in 20 ml of deionized water, and after cooling to a constant temperature in an ice water bath, it was uniformly added to the solution in 1) at a speed of 5 ml / min through a constant pressure dropping funnel, and stirred at 200 r / min during the addition process, and after the addition was completed, the stirring was stopped and the reaction was allowed to stand in an ice water bath for 24 hours, and then the chiral polyaniline was prepared by filtering, washing, centrifuging, and freeze-drying.

[0075] <Comparative Example 3>

[0076] 1) The peanut shell was repeatedly cleaned with deionized water and ethanol to remove surface impurities, then soaked in a 0.5 mol / L KHCO3 solution for 6 hours, filtered, and dried.

[0077] 2) The peanut shell treated in 1) was placed in a tube furnace and calcined under N2 atmosphere, the heating rate was 20℃ / min, the calcination temperature was 1200℃, the holding time was 35 min, and then ground after natural cooling to room temperature to prepare a biomass carbon precursor.

[0078] 3) 0.45 ml of aniline monomer, 1.2 g of camphor sulfonic acid, and 0.15 g of mandelic acid were fully dissolved in 50 ml of deionized water, and then 0.4 g of the biomass carbon precursor was weighed and immersed in the above solution. After ultrasonic stirring and stirring to obtain a uniform and stable suspension pre-solution, ice water bath cooling was performed to 0℃.

[0079] 4) 1 g of ammonium persulfate was weighed and fully dissolved in 20 ml of deionized water, and then cooled to a constant temperature in an ice water bath. After that, it was uniformly added to the suspension liquid in 3) at a speed of 5 ml / min through a constant pressure dropping funnel, stirred at 200 r / min during the dropping process, and then stopped stirring after the dropping was completed. After that, it was placed in an ice water bath and reacted for 24 hours, and then filtered, washed, centrifuged, and freeze-dried to prepare a chiral polyaniline / biomass carbon composite wave-absorbing material.

[0080] <Comparative Example 4>

[0081] 1) The date cluster was repeatedly cleaned with deionized water and ethanol to remove surface impurities, then soaked in a 0.5 mol / L KHCO3 solution for 6 hours, filtered, and dried.

[0082] 2) The date cluster treated in 1) was placed in a tube furnace and calcined under N2 atmosphere, the heating rate was 20℃ / min, the calcination temperature was 1200℃, the holding time was 35 min, and then ground after natural cooling to room temperature to prepare a biomass carbon precursor.

[0083] 3) 0.45 ml of aniline monomer was fully dissolved in 50 ml of dilute hydrochloric acid with a concentration of 1.5 mol / L, and then 0.4 g of the biomass carbon precursor was weighed and immersed in the above solution. After ultrasonic stirring and stirring to obtain a uniform and stable suspension pre-solution, ice water bath cooling was performed to 0℃.

[0084] 4) 1 g of ammonium persulfate was weighed and fully dissolved in 20 ml of deionized water, and then cooled to a constant temperature in an ice water bath. After that, it was uniformly added to the suspension liquid in 3) at a speed of 5 ml / min through a constant pressure dropping funnel, stirred at 200 r / min during the dropping process, and then stopped stirring after the dropping was completed. After that, it was placed in an ice water bath and reacted for 24 hours, and then filtered, washed, centrifuged, and freeze-dried to prepare a chiral polyaniline / biomass carbon composite wave-absorbing material.

[0085] <Comparative Example 5>

[0086] A preparation method of a chiral polyaniline / biomass carbon composite wave-absorbing material, the preparation process of which is basically the same as that of Example 1, except that the heating rate is adjusted to 5 ℃ / min.

[0087] <Comparative Example 6>

[0088] A preparation method of a chiral polyaniline / biomass carbon composite wave-absorbing material, the preparation process of which is basically the same as that of Example 1, except that the calcination temperature is adjusted to 800 ℃.

[0089] <Wave-absorbing performance comparison>

[0090] The wave-absorbing materials prepared in Examples <1-4> and Comparative Example <1-6> are mixed with paraffin at a mass ratio of 3:1, and then pressed into standard test samples. Based on the coaxial reflection / transmission method, a vector network analyzer is used to test the wave-absorbing performance of the samples at a frequency of 2-18 GHz.

[0091] The wave-absorbing performance of the wave-absorbing materials prepared in Examples <1-4> and Comparative Example <1-6> is shown in the following table:

[0092] Group Thickness (mm) Minimum reflection loss value (dB) Effective absorption bandwidth (GHz) Example 1 1.2 -51.75 4.86 Example 2 1.9 -48.65 4.72 Example 3 1.5 -49.38 4.88 Example 4 1.7 -48.65 4.64 Comparative Example 1 2.5 -20.36 2.24 Comparative Example 2 2.0 -28.65 2.68 Comparative Example 3 1.7 -40.28 3.68 Comparative Example 4 1.8 -43.28 4.16 Comparative Example 5 1.2 -46.65 4.52 Comparative Example 6 1.2 -45.12 4.34

[0093] <1> As shown by Comparative Example 1 and Comparative Example 2, the wave-absorbing performance of a single chiral material without compounding is significantly reduced.

[0094] <2> As shown by Comparative Example 3 and Comparative Example 4, the wave-absorbing performance of a single-handed composite material formed by compounding a chiral material and a non-chiral material is greatly improved, but still lower than that of the double-handed composite wave-absorbing material of Example 1-4.

[0095] It can be seen that, compared with a wave-absorbing body formed by a single material, a composite wave-absorbing material formed by component regulation and cooperation can exhibit excellent wave-absorbing performance, which is mainly due to the synergistic effect of multiple electromagnetic wave loss mechanisms and the improvement of impedance matching. Compared with a single-handed composite wave-absorbing material, a double-handed composite material formed by in-situ growth of two chiral materials with different scales can exhibit special optical rotation and circular dichroism, and produce more rich cross-polarization coupling effects under the action of an alternating electromagnetic field, so that multiple electromagnetic wave loss mechanisms are mutually beneficial, thereby greatly improving the wave-absorbing performance.

[0096] <3>From the comparative example 5 and the comparative example 6, when the high-temperature carbonization activation treatment is not carried out according to the temperature rising rate defined in the present application or the carbonization activation temperature defined in the present application, the wave-absorbing performance of the wave-absorbing material obtained finally is reduced compared with the example 1, and the wave-absorbing performance of the wave-absorbing material of the comparative example 5 is superior to that of the comparative example 6, which can be seen that the influence of the carbonization temperature on the wave-absorbing performance of the wave-absorbing material obtained finally is greater than the influence of the temperature rising rate on the wave-absorbing performance of the wave-absorbing material obtained finally.

[0097] It can be seen that: the biomass material with the chiral characteristics of the natural helical structure is subjected to the carbonization activation treatment under the specific conditions, the biomass carbon after the carbonization activation treatment perfectly inherits the chiral characteristics, the high temperature rising rate is used to rapidly rise to the high carbonization temperature, the reactivity of the biomass can be sufficiently reduced, the burn loss rate in the low temperature environment is reduced, and the biomass after the carbonization activation can perfectly inherit the chiral characteristics.

[0098] The specific embodiments of the present application are described above. It should be understood that the present application is not limited to the specific embodiments described above, and various modifications or changes can be made by those skilled in the art within the scope of the claims, which does not affect the essential content of the present application.

Claims

1. A method for preparing a bifurcated polyaniline / biomass carbon composite microwave absorbing material, characterized in that: The specific steps are as follows: S1: The biomass with natural helical structure chiral characteristics is cleaned, impurity-removed, soaked, filtered, and dried to obtain clean biomass for standby use; The soaking solution is a 0.5-2 mol / L KHCO3 solution, and the soaking time is 3-12 h, which is used for subsequent high-temperature carbonization activation; S2: The clean biomass obtained in S1 is high-temperature carbonized and activated under vacuum or inert atmosphere, and after calcination, it is naturally cooled to room temperature to obtain a chiral biomass carbon precursor for standby use; The high-temperature carbonization activation process is as follows: the temperature is raised to 1100-1200℃ at a heating rate of 15-25℃ / min, and the temperature is kept for 30-60 min; S3: The chiral biomass carbon precursor prepared in S2 is immersed in aniline monomer and chiral complex inducer aqueous solution, and is fully stirred and ultrasonically oscillated, and then is cooled in an ice water bath; The chiral complex inducer is a mixture of camphor sulfonic acid and mandelic acid in a mass ratio of 10:1-2:1; the mass ratio of the chiral biomass carbon precursor to the aniline monomer is 5:1-1:5, and the mass ratio of the aniline monomer to the chiral complex inducer is 1:1-1:4; S4: The initiator is dissolved in deionized water, and is added dropwise to the suspension liquid prepared in S3, and then is placed, and then is filtered, washed, and freeze-dried to obtain a double-chiral polyaniline / biomass carbon composite wave-absorbing material; The mass ratio of the chiral biomass carbon precursor to the aniline monomer is 2:1-1:

2.

2. The preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material according to claim 1, characterized in that: The high-temperature carbonization activation process is further optimized as follows: the temperature is raised to 1100-1200℃ at a heating rate of 20-25℃ / min, and the temperature is kept for 30-45 min.

3. The preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material according to claim 1, characterized in that: The biomass with natural helical structure chiral characteristics is a fluffy fruit cluster or a stem.

4. The preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material according to claim 3, characterized in that: The biomass with natural helical structure chiral characteristics is a camphor fruit cluster, a dandelion fruit cluster, a reed fruit cluster, a wheat awn, or a corn silk.

5. The preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material according to claim 1, characterized in that: The chiral complex inducer in step S3 is a mixture of camphor sulfonic acid and mandelic acid in a mass ratio of 6:1-5:

1.

6. The preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material according to claim 1, characterized in that: The mass ratio of the chiral biomass carbon precursor to the aniline monomer in step S3 is 2:1-1:

2.

7. The preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material according to claim 1, characterized in that: The mass ratio of the chiral biomass carbon precursor to the aniline monomer in step S3 is 2:1-1:

2.

8. The preparation method of the chiral polyaniline / biomass carbon composite wave-absorbing material according to claim 1, characterized in that: The mass ratio of the chiral biomass carbon precursor to the aniline monomer in step S3 is 2:1-1:

2.

9. A dual-chiral polyaniline / biomass carbon composite wave-absorbing material, characterized in that: The dropping speed of the initiator aqueous solution in step S4 is 1-8 ml / min, and the dropping is carried out at a stirring speed of 50-500 r / min, and after the dropping is completed, the reaction is placed for 2-20 h. The preparation method is prepared by any one of claims 1-8.

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