Preparation method and application of bowl-shaped polyaniline microspheres

Abstract

The invention relates to a preparation method and application of bowl-shaped polyaniline microspheres, and polyaniline microspheres with regular bowl-shaped morphology are synthesized by accurately controlling key parameters such as the oxidation degree of aniline monomers, the template size, the dosage of a polymerization initiator and the like. The bowl-shaped polyaniline microspheres are formed by self-assembly of polyaniline molecules, and the interior of each bowl-shaped polyaniline microsphere is provided with a continuous and uniformly-distributed nano-scale pore structure. Due to the unique bowl opening and bowl bottom sizes in the bowl-shaped microsphere structure, the microsphere has the characteristics of concave cavity, micron hollow hemisphere shape, nanoscale bowl wall thickness, high surface area-volume ratio and high porosity at the same time, more active sites can be provided, and the bowl-shaped microsphere structure can be used for supercapacitor electrodes, gas sensor electrodes and electromagnetic shielding materials.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials, and specifically relates to a method for preparing and applying bowl-shaped polyaniline microspheres. Background Technology

[0002] Polyaniline (PANI), as a typical conductive polymer material, has shown broad application prospects in many fields due to its advantages such as inexpensive and readily available raw materials, simple synthesis methods, good environmental stability, and ease of doping. However, traditional polyaniline materials are mostly irregular particles or blocks with relatively small specific surface areas and limited active sites, which to some extent restricts their application in various fields. For example, in supercapacitors, a larger specific surface area and suitable pore structure help improve the capacitance performance of electrode materials; in gas sensors, special microstructures can enhance the adsorption and desorption capabilities of target gases, thereby improving the sensor's sensitivity and response speed. Traditional polyaniline materials cannot meet these application requirements. Therefore, developing polyaniline materials with novel microstructures has become one of the current research hotspots.

[0003] Currently, although there are some reports on the preparation of polyanilines with special morphologies, research on polyanilines with bowl-shaped microsphere structures is relatively limited. The bowl-shaped microsphere structure not only helps to increase the specific surface area, but the unique bowl-shaped cavity can also provide more active sites and storage space, which is beneficial for the adsorption, storage, and reaction of substances, and is expected to significantly improve the performance of polyanilines in applications such as electrodes, sensors, and electromagnetic shielding. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for preparing and applying bowl-shaped polyaniline microspheres, so as to overcome the problem that the existing polyaniline structure has a relatively small specific surface area and limited active sites, which restricts the application effect.

[0005] This invention provides a method for preparing bowl-shaped polyaniline microspheres, comprising the following steps:

[0006] (1) Sulfonated polystyrene microspheres were added to deionized water and mixed evenly to obtain component A;

[0007] (2) Add the oxidized aniline to the doped acid and mix evenly to obtain component B;

[0008] (3) Add component B to component A and mechanically stir in an ice-water bath to mix evenly to obtain component C;

[0009] (4) Component C was continuously stirred at low temperature and an initiator was added to initiate the reaction; then centrifuged, washed and dried to obtain polyaniline@polystyrene composite microspheres;

[0010] (5) Dissolve the polyaniline@polystyrene composite microspheres in a template removal solvent, mix and stir, then wash and dry to obtain bowl-shaped polyaniline microspheres.

[0011] Preferably, in step (1), the sulfonated polystyrene microspheres are prepared by adding 30-80 mL of concentrated sulfuric acid to 2.0 g of polystyrene microspheres, mixing thoroughly, and heating and stirring at 50-70 °C for 3-7 hours.

[0012] Preferably, step (2) involves oxidizing aniline by ultrasound or by heating and stirring.

[0013] Further, the aniline oxidation in step (2) specifically involves: sonicating the aniline solution for more than 0.5 hours or heating and stirring at 40°C for more than 0.5 hours to oxidize the solution to a yellowish-brown color.

[0014] Preferably, the doping acid in step (2) includes at least one of hydrochloric acid, sulfuric acid, nitric acid, camphor sulfonic acid, dodecylbenzene sulfonic acid, salicylic acid, or sulfosalicylic acid, and the concentration of the doping acid is in the range of 0.2~2.0 mol·L⁻¹. -1 The molar ratio of doped acid to aniline is 2~10:1.

[0015] Preferably, in step (3), the volume ratio of component B to component A is 10:1.

[0016] Preferably, the initiator in step (4) includes at least one of ammonium persulfate, potassium persulfate, hydrogen peroxide, and ferrous salt.

[0017] Preferably, the molar ratio of aniline to initiator in step (4) is 1:2 to 3:1.

[0018] Preferably, the reaction initiation time in step (4) is 12 to 36 hours and the temperature is 0 to 10 °C.

[0019] Preferably, in step (5), the template removal solvent is N,N-dimethylformamide (DMF), the stirring time is 2-5 hours, and the temperature is 10-25 °C.

[0020] This invention provides a bowl-shaped polyaniline microsphere prepared according to the above preparation method, which has the characteristics of concave cavity, micron-sized hollow hemisphere, high surface area-to-volume ratio, and high porosity.

[0021] The present invention also provides an application of the above-mentioned bowl-shaped polyaniline microspheres in the fields of supercapacitor electrodes, gas sensor electrodes, and electromagnetic shielding materials.

[0022] This invention synthesizes polyaniline microspheres with a regular bowl-shaped morphology by precisely controlling key parameters such as the oxidation degree of aniline monomers, template size, and polymerization initiator dosage. These bowl-shaped polyaniline microspheres are formed by the self-assembly of polyaniline molecules and possess a continuous and uniformly distributed nanoscale porous structure. Compared to conventional spherical microsphere structures, the unique bowl-shaped microsphere structure, with its distinctive rim and bottom dimensions, simultaneously provides the microspheres with features such as concave cavities, micron-sized hollow hemispheres, nanoscale bowl wall thickness, high surface area-to-volume ratio, and high porosity.

[0023] Beneficial effects

[0024] This invention provides a simple and economical method for preparing bowl-shaped polyaniline microspheres. The bowl-shaped structure and the presence of internal nanoporous structures significantly increase the specific surface area of ​​the material. Testing shows that its specific surface area can reach 30.55 m². 2 The / g value represents a significant improvement over traditional polyaniline materials, providing more active sites for their application in energy storage and gas sensing, which helps to improve related performance and demonstrates promising application prospects. Attached Figure Description

[0025] Figure 1 This is a scanning electron microscope image of the bowl-shaped polyaniline microspheres prepared in Example 1 of the present invention.

[0026] Figure 2 The nitrogen isotherm adsorption-desorption curves are shown for the bowl-shaped polyaniline microspheres prepared in Example 1 of this invention.

[0027] Figure 3 This is a scanning electron microscope image of the polyaniline hollow microspheres prepared in Comparative Example 1 of this invention.

[0028] Figure 4 The nitrogen isotherm adsorption-desorption curves are shown for the polyaniline hollow microspheres prepared in Comparative Example 1 of this invention. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0030] Example 1

[0031] This embodiment provides a bowl-shaped polyaniline microsphere, which is prepared by the following method:

[0032] (1) Preparation of sulfonated polystyrene microsphere template: PVP stabilizer (1.0 g) was dissolved in ethanol (38.2 ml) and placed in a three-necked round-bottom flask equipped with a condenser and a magnetic stirrer. The reaction vessel was then heated to 70 °C under nitrogen purging. Subsequently, a solution of styrene monomer (15 g) pre-dissolved in azobisisobutyronitrile (AIBN) (0.15 g) was added to the reaction vessel and stirred vigorously for 12 hours to allow the styrene to polymerize. The product was purified by repeated centrifugation, washed with ethanol, and dried in a vacuum oven at 50 °C to finally obtain white fine powder polystyrene microspheres (PS). The dried PS fine powder (2.0 g) and concentrated sulfuric acid (98%, 60 ml) were placed in a 100 ml conical flask, ultrasonically dispersed, and then sulfonated for 5 h under magnetic stirring at 50 °C. After cooling to room temperature, the product was repeatedly centrifuged (6000 rpm) to separate it, washed with a large amount of ethanol, and dried to obtain yellow fine powder sulfonated polystyrene microspheres (SPS); the sulfonated polystyrene microspheres (1.0 g) were dispersed in 40 ml of water to obtain component A.

[0033] (2) Aniline treatment: First, the aniline reagent is distilled under reduced pressure at 80 °C. Then, the distilled aniline monomer solution is stirred at 40 °C for 1 hour to oxidize it, so that the solution turns yellowish-brown. 0.254 g of the oxidized aniline monomer is added to 4 ml of 1 M HCl aqueous solution to obtain component B.

[0034] (3) Add component B to component A and stir in an ice-water bath for 5 hours to obtain component C.

[0035] (4) Component C was continuously stirred and 5 ml of an aqueous solution containing 0.6 g of [NH4]2S2O8 was added. The mixture was stirred slowly at 0 °C to allow the polymerization reaction to continue for 24 hours. After repeated centrifugation and redispersion, the sulfonated polystyrene@polyaniline composite microspheres (SPS@PANI) were obtained after washing and drying.

[0036] (5) Template removal: Take 0.5 g SPS@PANI, add 20 mL N,N-dimethylformamide, stir at room temperature for 5 hours, wash with ethanol, centrifuge and dry to obtain cup-shaped polyaniline microspheres, as shown. Figure 1 The scanning electron microscope image (SEM) is shown below.

[0037] 0.5 g of bowl-shaped polyaniline microspheres were taken, and the specific surface area was measured using a fully automated rapid specific surface area and porosity analyzer (BET) at a test temperature of 100 ℃. Nitrogen adsorption / desorption isotherms and pore size distribution diagrams were plotted, as shown below. Figure 2 As shown in Table 1, the specific surface area, pore volume, and other relevant data of the bowl-shaped polyaniline microspheres are 30.553 m². 2 / g and pore volume is 0.164 cm³ 3 / g indicates that the prepared bowl-shaped polyaniline microspheres have a high specific surface area, which can provide more active sites and accommodation space.

[0038] Comparative Example 1

[0039] This comparative example provides hollow polyaniline microspheres, prepared using the same method as in Example 1, except that the aniline monomer solution after vacuum distillation is not oxidized during the aniline treatment process and is directly used for the synthesis of SPS@PANI composite microspheres. The steps for preparing the sulfonated polystyrene microsphere template, preparing the sulfonated polystyrene@polyaniline composite microspheres, and template removal are all the same as in Example 1. Finally, hollow polyaniline microspheres are synthesized. Figure 3 The scanning electron microscope image of ab is shown.

[0040] 0.5 g of hollow polyaniline microspheres were taken, and the specific surface area was measured using a fully automated rapid specific surface area and porosity analyzer at a test temperature of 100 ℃. Nitrogen adsorption / desorption isotherms and pore size distribution diagrams were plotted. Figure 4 As shown in Table 1, the specific surface area, pore volume, and other relevant data of the polyaniline hollow microspheres are 24.785 m². 2 / g and pore volume of 0.081 cm³ 3 / g, significantly smaller than the bowl-shaped polyaniline microspheres. This demonstrates that the bowl-shaped morphology prepared using the method of this invention can significantly increase the specific surface area and pore volume of polyaniline, thereby providing more active sites and accommodating space, and can be applied in the fields of capacitor electrodes, gas sensor electrodes, and electromagnetic shielding materials.

[0041] Table 1. BET test results of the bowl-shaped polyaniline microspheres prepared in Example 1 and the hollow polyaniline microspheres prepared in Comparative Example 1.

[0042]

Claims

1. A method for preparing bowl-shaped polyaniline microspheres, comprising the following steps: (1) Sulfonated polystyrene microspheres were added to deionized water and mixed evenly to obtain component A; (2) Add the oxidized aniline to the doped acid and mix evenly to obtain component B; (3) Add component B to component A and mechanically stir in an ice-water bath to mix evenly to obtain component C; (4) Component C was continuously stirred at low temperature and an initiator was added to initiate the reaction; then centrifuged, washed and dried to obtain polyaniline@polystyrene composite microspheres; (5) Dissolve the polyaniline@polystyrene composite microspheres in a template removal solvent, mix and stir, then wash and dry to obtain bowl-shaped polyaniline microspheres.

2. The preparation method according to claim 1, characterized in that, In step (1), sulfonated polystyrene microspheres are prepared by adding 30-80 mL of concentrated sulfuric acid to 2.0 g of polystyrene microspheres, mixing thoroughly, and heating and stirring at 50-70 °C for 3-7 hours.

3. The preparation method according to claim 1, characterized in that, Step (2) involves oxidizing aniline by ultrasound or heating and stirring, specifically by sonicating the aniline solution for more than 0.5 hours or heating and stirring at 40 °C for more than 0.5 hours to oxidize the solution to a yellowish-brown color.

4. The preparation method according to claim 1, characterized in that, The doping acid in step (2) includes at least one of hydrochloric acid, sulfuric acid, nitric acid, camphor sulfonic acid, dodecylbenzene sulfonic acid, salicylic acid, or sulfosalicylic acid, and the concentration of the doping acid is 0.2~2.0 mol·L⁻¹. -1 The molar ratio of doped acid to aniline is 2~10:

1.

5. The preparation method according to claim 1, characterized in that, In step (3), the volume ratio of component B to component A is 10:

1.

6. The preparation method according to claim 1, characterized in that, The initiator in step (4) includes at least one of ammonium persulfate, potassium persulfate, hydrogen peroxide, and ferrous salt.

7. The preparation method according to claim 1, characterized in that, In step (4), the molar ratio of aniline to initiator is 1:2 to 3:1; the initiation reaction time is 12 to 36 hours and the temperature is 0 to 10 °C.

8. The preparation method according to claim 1, characterized in that, In step (5), the template removal solvent is N,N-dimethylformamide, the stirring time is 2-5 hours, and the temperature is 10-25 ℃.

9. A bowl-shaped polyaniline microsphere prepared by the preparation method according to claim 1.

10. The application of the bowl-shaped polyaniline microspheres as described in claim 9 in the fields of supercapacitor electrodes, gas sensor electrodes, and electromagnetic shielding materials.

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