CN111138673A - Preparation method of self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material - Google Patents
Preparation method of self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material Download PDFInfo
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Abstract
The invention discloses a preparation method of a self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which comprises the following steps of dissolving aniline in an organic solvent to form an oil phase suspension; modifying the cobalt powder to obtain modified cobalt powder with rich amino groups on the surface, namely the cobalt powder has polyaniline growth sites on the surface; dissolving modified cobalt powder, gallic acid and ammonium persulfate in deionized water to obtain an aqueous phase solution; and step four, slowly dripping the aqueous phase solution into the oil phase suspension to form a self-assembly reaction system, carrying out polymerization reaction under a heat preservation condition, and carrying out post-treatment after the reaction is finished to obtain the polyaniline/cobalt core-shell sphere. The invention has the advantages of stability, excellent wave absorbing effect and the like.
Description
Technical Field
The invention belongs to the field of materials, relates to a wave-absorbing material, and particularly relates to a preparation method of a self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material.
Background
With the continuous development of wireless technology, electromagnetic pollution not only worsens the environment, but also seriously harms human health, and people pay more and more attention to the harm of electromagnetic radiation and the influence of public environment. Therefore, the electromagnetic wave absorbing material plays an important role in stealth technology and protection of human beings. The good wave-absorbing material requires thin thickness, light weight and excellent electromagnetic wave absorption performance.
Polyaniline has the advantages of cheap monomers, easy synthesis, light weight, good conductivity, potential high-performance electromagnetic wave absorption performance and the like, and is one of the conductive high polymer materials with the greatest development prospect. Through different polymerization processes, polyaniline in various forms such as nano-particle form, nano-fiber form, nano-tube form, micro-sphere form and the like can be prepared. Among them, porous microspherical polyaniline has attracted much attention for its potential applications in drug delivery, biosensors, supercapacitors, electrodes, electromagnetic wave absorbing materials, and the like. Among a plurality of preparation processes, a template method and a template-free method are the most widely applied methods for preparing polyaniline with special morphology at present. The preparation method of the template method is complex and is limited by the size and shape of the existing template, meanwhile, some post-treatment is needed to be carried out on the sample, and the ordered polyaniline structure is difficult to maintain after the template is removed. On the contrary, the template-free self-assembly method is a simple, efficient and controllable method for synthesizing the porous microspherical polyaniline.
However, the polyaniline wave-absorbing material with a single component has the defects of single loss mechanism, narrow wave-absorbing frequency band and the like. Although some multi-component wave-absorbing materials containing polyaniline exist at present, for example, the invention application with the application number of 201310562605.5 discloses a graphene/polyaniline/cobalt composite wave-absorbing material and a preparation method thereof, the invention application with the application number of 201210005404.0 discloses an expanded graphite/polyaniline/cobalt ferrite wave-absorbing material and a preparation method thereof, and the like, the problems that the wave-absorbing effect is limited due to poor binding property of cobalt and polyaniline, and other components (such as graphene) are possibly required to be combined to improve the wave-absorbing performance and the like exist.
Disclosure of Invention
The invention provides a preparation method of a self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which overcomes the defects of the prior art.
In order to achieve the aim, the invention provides a preparation method of a self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which comprises the following steps of firstly, dissolving aniline in an organic solvent to form an oil phase suspension; modifying the cobalt powder to obtain modified cobalt powder with rich amino groups on the surface, namely the cobalt powder has polyaniline growth sites on the surface; dissolving modified cobalt powder, gallic acid and ammonium persulfate in deionized water to obtain an aqueous phase solution; and step four, slowly dripping the aqueous phase solution into the oil phase suspension to form a self-assembly reaction system, carrying out polymerization reaction under a heat preservation condition, and carrying out post-treatment after the reaction is finished to obtain the polyaniline/cobalt core-shell sphere.
Further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: and in the second step, the cobalt powder is sequentially subjected to silane coupling agent surface modification and nitration surface modification.
Further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: and in the fourth step, in the polymerization reaction process, ultrasonic devices are arranged on the two reaction interfaces of water and oil for carrying out ultrasonic treatment.
Further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: in the fourth step, the ultrasonic device performs ultrasonic treatment at intervals, the ultrasonic treatment is performed once every 30min, the duration time of one time is 1min, and the ultrasonic treatment lasts for the whole reaction process.
Further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: in the second step, the specific method for sequentially carrying out silane coupling agent surface modification and nitration surface modification on the cobalt powder comprises the following steps: step a, ethanol is divided according to volume fraction: preparing 50mL of mixed solution by using water at a ratio of 9:1, adding 2g of cobalt powder into the solution, slowly dripping 0.2g of KH-550 into the solution, carrying out ultrasonic treatment for 15min, adding acetic acid to adjust the pH value to be 5, carrying out ultrasonic treatment again and stirring for 4h, carrying out suction filtration and washing on the product, drying at a temperature of 50 ℃ for 24h, and collecting the product, wherein the reaction formula is as follows:
step b, weighing 1.5g of the product obtained in the step a, adding the product into 50mL of 1mol/L HNO3To the solution, 5mL of 0.01mol/L NH was added dropwise2NH2·H2O in solution, 0.05g FeCl was added3And 6H2O, stirring the mixture for 3H at the stirring speed of 50rpm, performing suction filtration and washing on the product, and drying at 50 ℃ for 24H to obtain modified cobalt powder with the surface rich in amino groups, wherein the reaction formula is as follows:
further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: in the first step, aniline is purified through reduced pressure distillation, then the purified aniline is dissolved in an organic solvent of carbon tetrachloride, the concentration of the aniline is 0.05-1mol/L, stirring is carried out for 1h, and the stirring speed is 50rpm, so that oil phase suspension with uniformly dispersed aniline is obtained.
The reduced pressure distillation is to reduce the boiling point of aniline by a vacuumizing method, so that aniline is distilled and purified at a lower temperature of about 80 ℃.
Further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: in the third step, the specific method of the third step is as follows: dissolving gallic acid, ammonium persulfate and modified cobalt powder in deionized water, heating and stirring in a 50 ℃ water bath kettle for 1h until the gallic acid is completely dissolved to obtain a water phase solution; in the aqueous phase solution, the concentration of the gallic acid is 0.02-0.4mol/L, the concentration of the ammonium persulfate is 0.05-1mol/L, and the content of the modified cobalt powder is 0.5 g/mL.
Further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: wherein the molar ratio of the gallic acid to the aniline is 1: 2.5; the molar ratio of ammonium persulfate to aniline is 1: 1.
Further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: the specific method of the step four is as follows: transferring the oil phase suspension liquid obtained in the step one into a closed heat-preservation reaction kettle, stirring at the speed of 100rpm, introducing inert protective gas, and arranging an ultrasonic device on the surface of the oil phase suspension liquid; transferring the aqueous phase solution obtained in the third step into a circulating separating funnel, installing the circulating separating funnel on a closed heat-preservation reaction kettle, and controlling the aqueous phase solution to be dripped onto the surface of the oil phase suspension in the closed heat-preservation reaction kettle at the speed of 20 drops/min to form an oil-water reaction system, wherein the adding amount ratio of the oil phase suspension to the aqueous phase solution is 1: 1; the reaction kettle is placed in a circulating water bath kettle at the temperature of 30 ℃ for heat preservation, the temperature fluctuation range is controlled to be +/-0.9 ℃, the reaction is carried out for 12 hours, and in the whole reaction process, ultrasonic treatment is carried out at intervals for once every 30 minutes, and the one-time duration is 1 min.
Further, the invention provides a preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which can also have the following characteristics: and in the fourth step, after the reaction is finished, removing the lower oil phase, washing the upper water phase with water, centrifuging, and drying at 50 ℃ for 12h to obtain the polyaniline/cobalt core-shell sphere.
The invention has the beneficial effects that:
firstly, superfine cobalt powder with excellent magnetic loss is combined with porous polyaniline microspheres, a polyaniline/cobalt core-shell sphere structure with dielectric loss and magnetic loss is researched, meanwhile, the special porous core-shell structure can effectively avoid the electromagnetic shielding problem caused by polyaniline coating, namely, the weakening of the coating structure on the wave absorbing capacity of a cobalt core is eliminated. The polyaniline shell on the surface can effectively transmit electromagnetic waves while exerting the dielectric loss of the electromagnetic waves, the electromagnetic waves can be conducted to the cobalt core through the polyaniline, the effect of the polyaniline on the magnetic loss of the electromagnetic waves is further improved, and the synergistic effect of the polyaniline shell and the cobalt core is fully exerted.
Secondly, modifying cobalt to enable the cobalt to have a large number of amino active groups to serve as growth sites of polyaniline, improving the binding property of the cobalt and the polyaniline, enabling the polyaniline to stably and uniformly grow on the cobalt to form a porous sphere with good appearance, and having high graphitization crystallization degree on the surface through Raman analysis, excellent dielectric loss and electromagnetic wave absorption performance, thereby improving the overall wave absorption performance of the material.
Meanwhile, aiming at the characteristics of the modified cobalt powder, a synthetic route suitable for the modified cobalt powder is designed: the modified cobalt powder has a large number of active groups on the surface and can be used as a growth site of aniline, and the ammonium persulfate can promote the rapid growth of aniline, so that the contact reaction of the modified cobalt powder and aniline is not favorable for the uniform growth of the prepared polyaniline, and the contact reaction of the modified cobalt powder and ammonium persulfate and aniline is designed.
And thirdly, arranging an ultrasonic device on a water-oil reaction interface, and operating the whole reaction process, thereby promoting the uniform dispersion of the core-shell spheres, preventing the generated polyaniline from agglomerating, avoiding the problem of the reduction of the electromagnetic wave absorption performance caused by agglomeration, improving the quality and the yield of products, and preparing the structural wave-absorbing functional body with stable appearance and performance. Meanwhile, in order to prevent the temperature of the reaction liquid from being changed violently due to continuous ultrasound so as to influence the quality of the product, interval ultrasound is designed to realize the agglomeration prevention effect.
Compared with other shapes, the porous polyaniline has larger specific surface area, the porous structure can enhance multiple reflection and scattering of electromagnetic waves, and further reduce the reflection rate of the electromagnetic waves, and meanwhile, an effective conductive network structure formed by the polyaniline can enhance the dielectric loss of the material, so that the electromagnetic attenuation performance in the material is enhanced, and the electromagnetic wave absorption is enhanced.
The self-assembly technology is effectively controllable, the ultrasonic agglomeration prevention technology can effectively improve the rate of finished products of core-shell structure materials, and the prepared polyaniline has stable morphology and electromagnetic wave absorption performance and has certain guiding significance for industrialized mass production of novel carbon material wave absorbers.
Drawings
FIG. 1 is a schematic diagram of a device for purifying aniline by vacuum distillation;
FIG. 2 is a schematic view of the structure of an apparatus for polymerization;
FIG. 3 is an infrared spectrum of sample 1-1 in example 1;
FIG. 4 is a Raman spectrum of sample 1-1 in example 1;
FIG. 5 is an XRD pattern of sample 1-1 of example 1;
FIG. 6 is an SEM photograph of sample 1-1 in example 1;
FIG. 7 is a TEM image of sample 1-1 in example 1;
FIG. 8 is a wave-absorbing performance curve diagram of each sample in each example.
Detailed Description
The present invention is further illustrated by the following specific examples.
Example 1
The embodiment provides a preparation method of a self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which comprises the following steps:
step one, dissolving aniline in an organic solvent to form an oil phase suspension.
Specifically, aniline is purified by reduced pressure distillation, as shown in fig. 1, and then the purified aniline is dissolved in an organic solvent of carbon tetrachloride, wherein the concentration of aniline is 0.05mol/L, and the mixture is stirred for 1h at the stirring speed of 50rpm, so that an oil phase suspension with uniformly dispersed aniline is obtained.
And step two, carrying out silane coupling agent surface modification and nitration surface modification on the cobalt powder to obtain modified cobalt powder with rich amino groups on the surface.
The specific method for modification comprises the following steps:
step a, ethanol is divided according to volume fraction: preparing 50mL of mixed solution with water of 9:1, adding 2g of cobalt powder into the solution, slowly dripping 0.2g of KH-550 into the solution, carrying out ultrasonic treatment for 15min, adding acetic acid to adjust the pH value to be 5, carrying out ultrasonic treatment again and stirring for 4h, carrying out suction filtration and washing on the product, drying at 50 ℃ for 24h, and collecting the product;
step b, weighing 1.5g of the product obtained in the step a, adding the product into 50mL of 1mol/L HNO3To the solution, 5mL of 0.01mol/L NH was added dropwise2NH2·H2O in solution, 0.05g FeCl was added3·6H2And O, stirring the mixture for 3 hours at the stirring speed of 50rpm, performing suction filtration and washing on the product, and drying at 50 ℃ for 24 hours to obtain the modified cobalt powder with the surface rich in amino.
And step three, dissolving the modified cobalt powder, the gallic acid and the ammonium persulfate in deionized water to obtain an aqueous phase solution.
Specifically, the gallic acid, ammonium persulfate and modified cobalt powder are dissolved in deionized water and then heated and stirred in a water bath kettle at 50 ℃ for 1h until the gallic acid is completely dissolved, so as to obtain a water phase solution. In the aqueous phase solution, the concentration of gallic acid is 0.02mol/L, the concentration of ammonium persulfate is 0.05mol/L, and the content of modified cobalt powder is 0.5 g/mL.
And step four, slowly dripping the aqueous phase solution into the oil phase suspension, carrying out polymerization reaction under the condition of heat preservation, and carrying out post-treatment after the reaction is finished to obtain the polyaniline/cobalt core-shell sphere.
Specifically, as shown in fig. 2, the oil phase suspension obtained in the first step is transferred to a closed heat preservation reaction kettle, stirring is carried out at a speed of 100rpm, inert protective gas is introduced, and an ultrasonic device is arranged on the surface of the oil phase suspension.
And then, transferring the aqueous phase solution obtained in the step three to a circulating separating funnel, installing the circulating separating funnel on a closed heat-preservation reaction kettle, and controlling the aqueous phase solution to be dripped onto the surface of the oil phase suspension in the closed heat-preservation reaction kettle at the speed of 20 drops/min to form an oil-water reaction system, wherein the adding amount ratio of the oil phase suspension to the aqueous phase solution is 1: 1.
The reaction kettle is placed in a circulating water bath kettle at the temperature of 30 ℃ for reaction for 12 hours, and ultrasound is performed at intervals in the whole reaction process for once every 30 minutes, wherein the duration of each time is 1 min.
After the reaction is finished, removing the lower oil phase, washing and centrifuging the upper water phase, and drying at 50 ℃ for 12h to obtain the polyaniline/cobalt core-shell sphere which is marked as a sample 1-1.
The same preparation process and conditions were used, and the modified cobalt powder was replaced with cobalt powder for comparison, and the obtained product was designated as sample example 1-2.
Example 2
The embodiment provides a preparation method of a self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which comprises the following steps:
step one, dissolving aniline in an organic solvent to form an oil phase suspension.
Specifically, aniline is purified by reduced pressure distillation, as shown in fig. 1, and then the purified aniline is dissolved in an organic solvent of carbon tetrachloride, wherein the concentration of aniline is 0.5mol/L, and the mixture is stirred for 1h at the stirring speed of 50rpm, so that an oil phase suspension with uniformly dispersed aniline is obtained.
And step two, carrying out silane coupling agent surface modification and nitration surface modification on the cobalt powder to obtain modified cobalt powder with rich amino groups on the surface.
The specific method for modification comprises the following steps:
step a, ethanol is divided according to volume fraction: preparing 50mL of mixed solution with water of 9:1, adding 2g of cobalt powder into the solution, slowly dripping 0.2g of KH-550 into the solution, carrying out ultrasonic treatment for 15min, adding acetic acid to adjust the pH value to be 5, carrying out ultrasonic treatment again and stirring for 4h, carrying out suction filtration and washing on the product, drying at 50 ℃ for 24h, and collecting the product;
step b, weighing 1.5g of the product obtained in the step a, adding the product into 50mL of 1mol/L HNO3To the solution, 5mL of 0.01mol/L NH was added dropwise2NH2·H2O in solution, 0.05g FeCl was added3·6H2And O, stirring the mixture for 3 hours at the stirring speed of 50rpm, performing suction filtration and washing on the product, and drying at 50 ℃ for 24 hours to obtain the modified cobalt powder with the surface rich in amino.
And step three, dissolving the modified cobalt powder, the gallic acid and the ammonium persulfate in deionized water to obtain an aqueous phase solution.
Specifically, the gallic acid, ammonium persulfate and modified cobalt powder are dissolved in deionized water and then heated and stirred in a water bath kettle at 50 ℃ for 1h until the gallic acid is completely dissolved, so as to obtain a water phase solution. In the aqueous phase solution, the concentration of gallic acid is 0.2mol/L, the concentration of ammonium persulfate is 0.5mol/L, and the content of modified cobalt powder is 0.5 g/mL.
And step four, slowly dripping the aqueous phase solution into the oil phase suspension, carrying out polymerization reaction under the condition of heat preservation, and carrying out post-treatment after the reaction is finished to obtain the polyaniline/cobalt core-shell sphere.
Specifically, as shown in fig. 2, the oil phase suspension obtained in the first step is transferred to a closed heat preservation reaction kettle, stirring is carried out at a speed of 100rpm, inert protective gas is introduced, and an ultrasonic device is arranged on the surface of the oil phase suspension.
And then, transferring the aqueous phase solution obtained in the step three to a circulating separating funnel, installing the circulating separating funnel on a closed heat-preservation reaction kettle, and controlling the aqueous phase solution to be dripped onto the surface of the oil phase suspension in the closed heat-preservation reaction kettle at the speed of 20 drops/min to form an oil-water reaction system, wherein the adding amount ratio of the oil phase suspension to the aqueous phase solution is 1: 1.
The reaction kettle is placed in a circulating water bath kettle at the temperature of 30 ℃ for reaction for 12 hours, and ultrasound is performed at intervals in the whole reaction process for once every 30 minutes, wherein the duration of each time is 1 min.
After the reaction is finished, removing the lower oil phase, washing and centrifuging the upper water phase, and drying at 50 ℃ for 12h to obtain the polyaniline/cobalt core-shell sphere which is marked as a sample 2-1.
The same preparation process and conditions were used, and the modified cobalt powder was replaced with cobalt powder for comparison, and the obtained product was designated as sample example 2-2.
Example 3
The embodiment provides a preparation method of a self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material, which comprises the following steps:
step one, dissolving aniline in an organic solvent to form an oil phase suspension.
Specifically, aniline is purified by reduced pressure distillation, as shown in fig. 1, and then the purified aniline is dissolved in carbon tetrachloride organic solvent, the concentration of aniline is 1mol/L, stirring is carried out for 1h, and the stirring speed is 50rpm, so as to obtain oil phase suspension with aniline uniformly dispersed.
And step two, carrying out silane coupling agent surface modification and nitration surface modification on the cobalt powder to obtain modified cobalt powder with rich amino groups on the surface.
The specific method for modification comprises the following steps:
step a, ethanol is divided according to volume fraction: preparing 50mL of mixed solution with water of 9:1, adding 2g of cobalt powder into the solution, slowly dripping 0.2g of KH-550 into the solution, carrying out ultrasonic treatment for 15min, adding acetic acid to adjust the pH value to be 5, carrying out ultrasonic treatment again and stirring for 4h, carrying out suction filtration and washing on the product, drying at 50 ℃ for 24h, and collecting the product;
step b, weighing 1.5g of the product obtained in the step a, adding the product into 50mL of 1mol/L HNO3To the solution, 5mL of 0.01mol/L NH was added dropwise2NH2·H2O in solution, 0.05g FeCl was added3·6H2And O, stirring the mixture for 3 hours at the stirring speed of 50rpm, performing suction filtration and washing on the product, and drying at 50 ℃ for 24 hours to obtain the modified cobalt powder with the surface rich in amino.
And step three, dissolving the modified cobalt powder, the gallic acid and the ammonium persulfate in deionized water to obtain an aqueous phase solution.
Specifically, the gallic acid, ammonium persulfate and modified cobalt powder are dissolved in deionized water and then heated and stirred in a water bath kettle at 50 ℃ for 1h until the gallic acid is completely dissolved, so as to obtain a water phase solution. In the aqueous phase solution, the concentration of gallic acid is 0.4mol/L, the concentration of ammonium persulfate is 1mol/L, and the content of modified cobalt powder is 0.5 g/mL.
And step four, slowly dripping the aqueous phase solution into the oil phase suspension, carrying out polymerization reaction under the condition of heat preservation, and carrying out post-treatment after the reaction is finished to obtain the polyaniline/cobalt core-shell sphere.
Specifically, as shown in fig. 2, the oil phase suspension obtained in the first step is transferred to a closed heat preservation reaction kettle, stirring is carried out at a speed of 100rpm, inert protective gas is introduced, and an ultrasonic device is arranged on the surface of the oil phase suspension.
And then, transferring the aqueous phase solution obtained in the step three to a circulating separating funnel, installing the circulating separating funnel on a closed heat-preservation reaction kettle, and controlling the aqueous phase solution to be dripped onto the surface of the oil phase suspension in the closed heat-preservation reaction kettle at the speed of 20 drops/min to form an oil-water reaction system, wherein the adding amount ratio of the oil phase suspension to the aqueous phase solution is 1: 1.
The reaction kettle is placed in a circulating water bath kettle at the temperature of 30 ℃ for reaction for 12 hours, and ultrasound is performed at intervals in the whole reaction process for once every 30 minutes, wherein the duration of each time is 1 min.
After the reaction is finished, removing the lower oil phase, washing and centrifuging the upper water phase, and drying at 50 ℃ for 12h to obtain the polyaniline/cobalt core-shell sphere which is marked as a sample 3-1.
The same preparation process and conditions were used, and the modified cobalt powder was replaced with cobalt powder for comparison, and the obtained product was designated as sample example 3-2.
The sample 1-1 of example 1 was characterized by infrared spectroscopy, Raman spectroscopy, XRD, SEM, and TEM.
Analysis of the IR spectrum FT-IR showed that the cobalt modification was at 1301cm after cobalt modification as shown in FIG. 3-1Has an N-H bending vibration absorption peak, and proves the generation of partial amino on the surface of the cobalt. Four characteristic peaks can be clearly seen by polyaniline/cobalt, and are respectively 1580cm-1，1485cm-1，1300cm-1And 1153cm-1Nearby. Consult the relevant manual, 1580cm-1And 1485cm-11300cm of C ═ C stretching vibration absorption peak respectively belonging to quinoid (Q) and benzene ring (B)-1Is the N-H bending vibration absorption peak of B, 1153cm-1These several characteristic peaks, which are vibration absorption peaks of N ═ Q ═ N, can help to analyze the internal structure, and thus it can be known that the form of the polyaniline produced is a form in a doped state.
The Raman spectrum was analyzed and as shown in FIG. 4, the sample was at 1384.6cm-1Has a weaker D peak, which indicates that the degree of disorder of polyaniline in the sample is lower, and is 1594.3cm-1Has stronger G peak, which indicates that the sample graphite has higher ordering degree, and ID/IG is 0.883, which indicates that the sample graphite has higher ordering degree and polyaniline crystal arrangement is more complete, which is beneficial to good conductive networkAnd the electromagnetic loss is further improved.
When the XRD pictures are analyzed, as shown in fig. 5, distinct cobalt characteristic peaks appear at 2 θ (44.1 °), (64.5 °), and (74.7 °), which proves that the cobalt element exists in the polyaniline/cobalt core-shell sphere, and the peak is hardly seen due to the weak peak plus the influence of the cobalt element.
When the SEM picture is analyzed, as shown in fig. 6, the polyaniline/cobalt core-shell spheres have substantially no dendritic and irregular forms, all samples are complete smooth spheres, and a part of the polyaniline/cobalt core-shell spheres begin to crack, forming a porous structure.
When TEM images are analyzed, as shown in fig. 7, it is evident that polyaniline/cobalt core-shell sphere structure with polyaniline coating the inner cobalt core has a spherical overall structure.
The wave absorbing performance of each sample in each example is analyzed, as shown in fig. 8, the wave absorbing performance of the polyaniline/cobalt core-shell ball prepared from different contents of aniline, gallic acid and cobalt powder is different, and comparison shows that the polyaniline/cobalt core-shell ball sample prepared from the modified cobalt powder has relatively better electromagnetic wave absorbing performance than the sample prepared from unmodified cobalt powder, which indicates that polyaniline and the modified cobalt powder have good binding property and the whole wave absorbing performance is improved.
Claims (10)
1. A preparation method of a self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material is characterized by comprising the following steps:
dissolving aniline in an organic solvent to form an oil phase suspension;
step two, modifying the cobalt powder to obtain modified cobalt powder with rich amino groups on the surface;
dissolving modified cobalt powder, gallic acid and ammonium persulfate in deionized water to obtain an aqueous phase solution;
and step four, slowly dripping the aqueous phase solution into the oil phase suspension, carrying out polymerization reaction under the condition of heat preservation, and carrying out post-treatment after the reaction is finished to obtain the polyaniline/cobalt core-shell sphere.
2. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 1, which is characterized in that:
and in the second step, sequentially carrying out silane coupling agent surface modification and nitration surface modification on the cobalt powder.
3. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 1, which is characterized in that:
and in the fourth step, in the polymerization reaction process, ultrasonic devices are arranged on the two reaction interfaces of water and oil for carrying out ultrasonic treatment.
4. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 3, which is characterized by comprising the following steps:
in the fourth step, the ultrasonic device performs ultrasonic treatment at intervals, the ultrasonic treatment is performed once every 30min, the duration time of one ultrasonic treatment is 1min, and the ultrasonic treatment lasts for the whole reaction process.
5. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 1 or 2, which is characterized by comprising the following steps:
in the second step, the specific method for sequentially carrying out silane coupling agent surface modification and nitration surface modification on the cobalt powder comprises the following steps:
step a, ethanol is divided according to volume fraction: preparing 50mL of mixed solution with water of 9:1, adding 2g of cobalt powder into the solution, slowly dripping 0.2g of KH-550 into the solution, carrying out ultrasonic treatment for 15min, adding acetic acid to adjust the pH value to be 5, carrying out ultrasonic treatment again and stirring for 4h, carrying out suction filtration and washing on the product, drying at 50 ℃ for 24h, and collecting the product;
step b, weighing 1.5g of the product obtained in the step a, adding the product into 50mL of 1mol/L HNO3To the solution, 5mL of 0.01mol/L NH was added dropwise2NH2·H2O in solution, 0.05g FeCl was added3·6H2And O, stirring the mixture for 3 hours at the stirring speed of 50rpm, performing suction filtration and washing on the product, and drying at 50 ℃ for 24 hours to obtain the modified cobalt powder with the surface rich in amino.
6. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 1, which is characterized in that:
in the first step, aniline is purified through reduced pressure distillation, then the purified aniline is dissolved in an organic solvent of carbon tetrachloride, the concentration of the aniline is 0.05-1mol/L, stirring is carried out for 1h, and the stirring speed is 50rpm, so that oil phase suspension with uniformly dispersed aniline is obtained.
7. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 1, which is characterized in that:
the third step is specifically as follows: dissolving the gallic acid, ammonium persulfate and modified cobalt powder in deionized water, heating and stirring in a water bath kettle at 50 ℃ for 1h until the gallic acid is completely dissolved to obtain the water-phase solution;
in the aqueous phase solution, the concentration of gallic acid is 0.02-0.4mol/L, the concentration of ammonium persulfate is 0.05-1mol/L, and the content of modified cobalt powder is 0.5 g/mL.
8. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 1, which is characterized in that:
wherein the molar ratio of the gallic acid to the aniline is 1: 2.5;
the molar ratio of the ammonium persulfate to the aniline is 1: 1.
9. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 1, which is characterized in that:
the specific method of the step four is as follows:
transferring the oil phase suspension liquid obtained in the step one into a closed heat-preservation reaction kettle, stirring at the speed of 100rpm, introducing inert protective gas, and arranging an ultrasonic device on the surface of the oil phase suspension liquid;
transferring the aqueous phase solution obtained in the third step into a circulating separating funnel, installing the circulating separating funnel on a closed heat-preservation reaction kettle, and controlling the aqueous phase solution to be dripped onto the surface of the oil phase suspension in the closed heat-preservation reaction kettle at the speed of 20 drops/min to form an oil-water reaction system, wherein the adding amount ratio of the oil phase suspension to the aqueous phase solution is 1: 1;
the reaction kettle is placed at the temperature of 30 ℃ for reaction for 12h, and ultrasound is performed at intervals for 30min once in the whole reaction process, wherein the duration of one time is 1 min.
10. The preparation method of the self-assembled porous polyaniline/cobalt core-shell spherical structure wave-absorbing material according to claim 9, characterized in that:
and in the fourth step, after the reaction is finished, removing the lower oil phase, washing and centrifuging the upper water phase, and drying at 50 ℃ for 12h to obtain the polyaniline/cobalt core-shell sphere.
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