Conductive expandable composite microspheres, and preparation method and application thereof

Abstract

The application discloses a kind of electrically conductive swellable composite microspheres and its preparation method and application, belong to electrically conductive material technical field.The application provides a kind of new electrically conductive swellable composite microspheres.The composite microspheres have swellable characteristics, in the expansion process, the graphene oxide (GO) layer and poly-3,4-ethylenedioxythiophene (PEDOT) layer on its surface not only can expand with it, but also can maintain effective conductive network structure in the process, thereby providing efficient, stable antistatic or conductive function for the prepared swellable composite microspheres.Not only that, the conductivity and size of the composite microspheres can be regulated by changing the content of GO and PEDOT and the expansion temperature, and the expanded composite microspheres have the characteristics of light weight, excellent elasticity, etc.

Description

Technical Field

[0001] This invention relates to a conductive expandable composite microsphere, its preparation method and application, belonging to the field of conductive materials technology. Background Technology

[0002] With the rapid development of the electronic information industry, higher demands are being placed on efficient and flexible conductive or antistatic composite materials. Among these, compounding conductive fillers with matrix materials is one of the most effective methods. For conductive fillers, spherical shell-structured conductive particles have become a new type of conductive particle that reduces the cost of conductive composite materials and improves their performance. However, most existing spherical shell-structured conductive particles are rigid, causing significant changes in conductivity during matrix material deformation. To address this challenge, current methods use flexible materials as the inner shell of the conductive particles, and then coat the surface of the flexible shell with a conductive substance. However, existing flexible conductive particles with spherical shell structures suffer from surface conductive shell damage during long-term use, and the surface conductive pathways are easily affected when the matrix material deforms.

[0003] In summary, designing and fabricating a spherical shell structure capable of significant deformation and stable conductivity is key to solving the aforementioned problems. However, obtaining a flexible conductive spherical shell that simultaneously possesses deformability and stable conductivity remains a major challenge in this field. Summary of the Invention

[0004] To address the aforementioned problems in the existing technology, this invention provides a deformable, electrically stable expandable composite microsphere and its preparation method.

[0005] When the expandable composite microspheres are heated, their volume expands immediately. The graphene oxide and poly(3,4-ethylenedioxythiophene) composite layer on the surface exhibits excellent elasticity and expands with them to form a conductive layer with excellent elasticity and stability, providing stable conductivity for the expandable composite microspheres.

[0006] The first objective of this invention is to provide a conductive expandable microsphere@GO@PEDOT composite microsphere, wherein the composite microsphere comprises expandable microspheres, graphene oxide (GO), and poly(3,4-ethylenedioxythiophene) (PEDOT), and GO and PEDOT are layered and coated on the surface of the expandable microspheres. Figure 1 ).

[0007] In one embodiment of the present invention, the expandable composite microspheres expand in volume during heat treatment and maintain their expanded shape and size after cooling; and they are conductive before and after expansion.

[0008] In one embodiment of the present invention, the expandable composite microspheres have a particle size of 1μm-50μm and an expansion temperature of 90℃-240℃.

[0009] In one embodiment of the present invention, the expandable composite microspheres can increase in volume to 2 to 100 times their original volume after expansion, and have elasticity and conductivity.

[0010] In one embodiment of the present invention, the expandable microspheres have a hollow structure, with the interior containing encapsulated gas and the outer shell being a thermoplastic polymer.

[0011] The second objective of this invention is to provide a method for preparing conductive expandable microspheres @GO@PEDOT composite microspheres, comprising the following steps:

[0012] (a) Expandable microspheres and positively charged graphene oxide were added to water and mixed to obtain an expandable microspheres@GO dispersion. The dispersion was then allowed to stand, filtered, purified and dried to obtain conductive expandable microspheres@GO.

[0013] (b) The expandable microspheres @GO obtained in step (a) were added to dichloromethane, a catalyst was added, and 3,4-thiophene dicarboxylic anhydride was added to react and expandable microspheres @GO-thiophene ester were prepared.

[0014] (c) The expandable microspheres @GO-thiophene ester and 3,4-ethylenedioxythiophene monomer obtained in step (b) are added to chloroform and an initiator is added to react and obtain a conductive expandable microspheres @GO@PEDOT dispersion.

[0015] (d) The conductive expandable microspheres @GO@PEDOT dispersion obtained in step (c) was allowed to stand, and then the upper solid was collected, purified, and dried to obtain conductive expandable microspheres @GO@PEDOT.

[0016] Furthermore, in step (a), the mass ratio of expandable microspheres to positively charged graphene oxide is 10:0.5 to 2.0.

[0017] Furthermore, in step (a), the mass ratio of expandable microspheres to water is 1:20 to 80.

[0018] Furthermore, in step (b), the mass ratio of expandable microspheres @GO to dichloromethane is 1:8 to 15.

[0019] Furthermore, the catalyst described in step (b) is acetamide.

[0020] Furthermore, the temperature of the reaction described in step (b) is 40–80 °C.

[0021] Furthermore, the reaction time described in step (b) is 60–120 min.

[0022] Furthermore, in step (b), the mass ratio of expandable microspheres@GO to catalyst is 3:0.5–2.

[0023] Furthermore, in step (b), the mass ratio of expandable microspheres @GO to 3,4-thiophene dicarboxylic anhydride is 30:1 to 8.

[0024] Furthermore, in step (c), the mass ratio of expandable microspheres @GO-thiophene ester to 3,4-ethylenedioxythiophene monomer is 3:0.2 to 1.5.

[0025] Furthermore, in step (c), the mass ratio of expandable microspheres @GO-thiophene ester to chloroform is 3:20 to 60.

[0026] Furthermore, the initiator mentioned in step (c) is at least one of ammonium persulfate, potassium persulfate, and ferric chloride.

[0027] Furthermore, in step (c), the mass ratio of expandable microspheres @GO-thiophene ester to initiator is 100:1 to 5.

[0028] Furthermore, the reaction temperature in step (c) is 20–25 °C.

[0029] Furthermore, the reaction time described in step (c) is 4 to 12 hours.

[0030] The present invention provides conductive expandable microspheres prepared according to the above method.

[0031] The conductive expandable microspheres provided by this invention have applications in electromagnetic shielding, static electricity elimination, conductivity, intelligent sensing, aerospace, military defense, ships and vessels, and information communication.

[0032] A third objective of this invention is to provide applications for the aforementioned conductive expandable microspheres.

[0033] Furthermore, the conductive expandable microspheres are used as conductive fillers.

[0034] Furthermore, the prepared conductive expandable microspheres @GO@PEDOT can be used alone or compounded with other materials and then mixed with polylactic acid, polyglycolic acid, or polyurethane dispersion, acrylic resin dispersion, or epoxy resin dispersion by melt processing to obtain composite materials with conductive or antistatic functions.

[0035] The beneficial effects of this invention are as follows:

[0036] Unlike traditional methods of obtaining conductive microspheres by gold plating on the surface of polymer microspheres, this invention provides a novel conductive microsphere, its preparation method, and its applications. The microspheres are expandable; during expansion, the graphene oxide (GO) layer and poly(3,4-ethylenedioxythiophene) (PEDOT) layer on their surface not only expand with the microspheres but also maintain an effective conductive network structure, thus providing the prepared expandable composite microspheres with efficient and stable antistatic or conductive functions. The conductivity and size of the microspheres can be controlled by changing the GO and PEDOT content and the expansion temperature. Furthermore, the expanded microspheres are lightweight and possess excellent elasticity. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the expandable composite microspheres in this invention.

[0038] Figure 2 This is a schematic diagram illustrating the preparation of expandable microspheres @GO@PEDOT in this invention.

[0039] Figure 3 This is a SEM image of the expandable microspheres in this invention.

[0040] Figure 4 This is a SEM image of the expandable microspheres @GO@PEDOT in Example 1.

[0041] Figure 5 This is a SEM image of the expandable microspheres @GO@PEDOT in Example 2.

[0042] Figure 6 This is a SEM image of the expandable microspheres @GO@PEDOT in Example 3. Detailed Implementation

[0043] The embodiments disclosed herein are examples of the invention, which may be embodied in various forms. Therefore, the detailed disclosure, including specific structural and functional details, is not intended to limit the invention, but merely to form the basis of the claims. It should be understood that the detailed description of the invention is not intended to limit but to cover all possible modifications, equivalents, and substitutions falling within the scope of the invention as defined by the appended claims. Throughout this application, the word "may" is used in an permissive sense rather than a mandatory sense. Similarly, unless otherwise stated, the words "comprising," "including," and "constituting as" mean "including but not limited to." The words "a" or "an" mean "at least one," and the words "a plurality of" mean more than one. When abbreviations or technical terms are used, these terms represent generally accepted meanings known in the art.

[0044] Source of raw materials

[0045] The expandable microspheres used in the examples were purchased from AkzoNobel, model numbers 031DU40, 920DU40, or 951DU120.

[0046] The modified graphene oxide used in the examples is hydroxylated graphene oxide, and the graphene oxide dispersion was purchased from Suzhou Carbon-rich Graphene Technology Co., Ltd.

[0047] The dichloromethane used in the examples was purchased from Sinopharm Chemical Reagent Co., Ltd., with a purity of ≥99.5%.

[0048] The acetamide used in the examples was purchased from Beijing Inokai Technology Co., Ltd., with a purity of ≥98%.

[0049] The 3,4-thiophene dicarboxylic anhydride used in the examples was purchased from Beijing Bailingwei Technology Co., Ltd., with a purity of ≥98%.

[0050] The chloroform used in the examples was purchased from Sinopharm Chemical Reagent Co., Ltd., with a purity of ≥98%.

[0051] The ferric chloride used in the examples was purchased from Sinopharm Chemical Reagent Co., Ltd., with a purity of ≥97%.

[0052] The ammonium persulfate used in the examples was purchased from Sinopharm Chemical Reagent Co., Ltd., with a purity of ≥98%.

[0053] The 3,4-ethylenedioxythiophene used in the examples was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with a purity of ≥99%.

[0054] The potassium persulfate used in the examples was purchased from Sinopharm Chemical Reagent Co., Ltd., with a purity of ≥98%.

[0055] The aniline used in the comparative example was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with a purity of ≥99.5%.

[0056] The hydroxylated carbon nanotubes used in the comparative examples were purchased from Shenzhen Suiheng Graphene Technology Co., Ltd., with a purity of ≥99% and a hydroxyl content of 1 mmol / g.

[0057] The pyrrole used in the comparative example was purchased from Shanghai McLean Biochemical Technology Co., Ltd., with a purity of ≥99%.

[0058] Example 1

[0059] (a) Add 5 parts of expandable microspheres and 0.5 parts of positively charged GO to 100 parts of water and stir for 30 min to obtain expandable microspheres@GO dispersion. Then, let it stand, filter, purify and dry the upper solid to obtain conductive expandable microspheres@GO.

[0060] (b) Add 3 parts of expandable microspheres @GO to 30 parts of dichloromethane solvent, add 1 part of catalyst acetamide, add 0.4 parts of 3,4-thiophene dicarboxylic anhydride, and react at 55°C for 100 min to prepare expandable microspheres @GO-thiophene ester;

[0061] (c) Add 3 parts of expandable microspheres @GO-thiophene ester and 0.5 parts of 3,4-ethylenedioxythiophene monomer to 40 parts of chloroform solvent, and add 0.05 parts of ferric chloride. Polymerize at 25°C for 10 h to obtain conductive expandable microspheres @GO@PEDOT dispersion.

[0062] (d) The dispersion obtained in step (c) was allowed to stand, and then the upper solid was collected, purified and dried to obtain 3 portions of expandable microspheres @GO@PEDOT.

[0063] Example 2

[0064] (a) 1.5 parts of expandable microspheres and 0.1 parts of positively charged GO were added to 100 parts of water and stirred for 30 min to obtain an expandable microspheres@GO dispersion. Then, the dispersion was allowed to stand, filtered, purified and dried to obtain conductive expandable microspheres@GO.

[0065] (b) Add 1 part of expandable microspheres @GO to 12 parts of dichloromethane solvent, add 0.5 parts of catalyst acetamide, add 0.2 parts of 3,4-thiophene dicarboxylic anhydride, and react at 70°C for 80 min to prepare expandable microspheres @GO-thiophene ester;

[0066] (c) Add 1 part of expandable microspheres @GO-thiophene ester and 0.2 parts of 3,4-ethylenedioxythiophene monomer to 15 parts of chloroform solvent, and add 0.03 parts of ammonium persulfate. Polymerize at 25°C for 6 h to obtain conductive expandable microspheres @GO@PEDOT dispersion.

[0067] (d) Allow the mixture obtained in step (c) to stand, then collect, purify and dry the upper solid to obtain 1 part of expandable microspheres @GO@PEDOT.

[0068] Example 3

[0069] (a) Add 5 parts of expandable microspheres and 1 part of positively charged GO to 100 parts of water, stir for 30 min to obtain expandable microspheres@GO dispersion, then let stand, filter, purify and dry the upper solid to obtain conductive expandable microspheres@GO;

[0070] (b) Add 3 parts of expandable microspheres @GO to 25 parts of dichloromethane solvent, add 0.8 parts of catalyst acetamide, add 0.2 parts of 3,4-thiophene dicarboxylic anhydride, and react at 80°C for 50 min to prepare expandable microspheres @GO-thiophene ester;

[0071] (c) Add 3 expandable microspheres @GO-thiophene ester and 1 part of 3,4-ethylenedioxythiophene monomer to 50 parts of chloroform solvent and add 0.06 parts of potassium persulfate. Polymerize at 25°C for 8 hours to obtain conductive expandable microspheres @GO@PEDOT dispersion.

[0072] (d) Allow the mixture obtained in step (c) to stand, then collect, purify and dry the upper solid to obtain 1 part of expandable microspheres @GO@PEDOT.

[0073] Comparative Example 1

[0074] Compared with Example 1, the use of graphene oxide in step (a) was removed, and the graft polymerization of PEDOT in steps (b) and (c) was not performed. All other steps were the same, and expandable microspheres were obtained.

[0075] Comparative Example 2

[0076] Compared with Example 1, the graft polymerization of PEDOT in steps (b) and (c) was not performed, but all other steps were the same, and expandable microspheres were obtained.

[0077] Comparative Example 3

[0078] Compared with Example 1, the EDOT monomer in step (c) was replaced with the same amount of ANI (aniline) monomer, while all other steps remained the same, to obtain expandable microspheres.

[0079] Comparative Example 4

[0080] Compared with Example 1, the graphene oxide in (a) was replaced with an equal amount of hydroxylated carbon nanotubes, while all other aspects remained the same, to prepare expandable microspheres.

[0081] Comparative Example 5

[0082] Compared with Example 1, the graphene oxide in (a) was replaced with an equal amount of hydroxylated carbon nanotubes, and the EDOT in (b) and (c) was replaced with an equal amount of PY (pyrrole) monomer, with all other aspects remaining the same, to prepare expandable microspheres.

[0083] Example 4

[0084] Uncoated expandable microspheres were placed in ovens at 80℃, 90℃, 160℃, 240℃, and 250℃ for 10 minutes to allow them to fully expand. The average particle size of the expanded microspheres at each temperature is recorded in Table 1.

[0085] Table 1. Particle size of composite microspheres after expansion at different temperatures

[0086]

[0087] Table 1 shows that the composite microspheres cannot expand at 80℃, and the higher the expansion temperature, the greater the expansion of the microspheres. When the expansion temperature rises to above 250℃, the microspheres rupture.

[0088] The volume and volume resistivity of the expandable composite microspheres obtained in Examples 1-3 and Comparative Examples 1-5 before and after expansion were recorded in Table 2 after being kept in an oven at 90°C for 10 min.

[0089] The volume and volume resistivity of the expandable composite microspheres obtained in Examples 1-3 and Comparative Examples 1-5 before and after expansion were recorded in Table 3 after being kept in an oven at 240°C for 10 min.

[0090] Table 2. Volume resistivity and particle size of composite microspheres in each example and comparative example at 90℃

[0091]

[0092] Table 3. Volume resistivity and particle size of composite microspheres in each example and comparative example at 240℃

[0093]

[0094] Schematic diagrams of the expandable composite microspheres in Examples 1-3 are shown below. Figure 1 As shown. Clearly, the encapsulated gas and thermoplastic polymer shell constitute an expandable microsphere, its surface coated with graphene oxide (GO) and grafted with a poly(3,4-ethylenedioxythiophene) (PEDOT) layer. Furthermore, Figure 3 SEM image of expandable microspheres. Figure 4 , 5 Figures 6 and 7 are SEM images of the expandable composite microspheres in Examples 1, 2, and 3, respectively. A comparison shows that in the expandable composite microspheres obtained in Example 1, the GO and PEDOT nanomaterials form a shell covering the surface of the expandable microspheres. Furthermore, as the GO and PEDOT content increases (Examples 2 and 3), the conductive shell covering the surface of the expandable microspheres gradually becomes completely complete. This structural change directly affects its mechanical properties and electromagnetic shielding performance.

[0095] Tables 2 and 3 list the changes in volume resistivity and particle size of the expandable microspheres@GO@PEDOT composite microspheres before and after expansion in each embodiment and comparative example. Clearly, the expansion amplitude of the composite microspheres in all cases was stable, with the particle size increasing by approximately 2 to 4 times. Furthermore, compared to the insulation (high volume resistivity) exhibited by the composite microspheres obtained in Comparative Example 1, Examples 1-3 exhibited a certain degree of conductivity, and the volume resistivity of the obtained composite microspheres gradually decreased with increasing GO and PEDOT content. When the expandable microspheres@GO@PEDOT composite microspheres in each embodiment and comparative example were heated and expanded, the volume resistivity of Examples 1-3 did not decrease significantly, while the composite microspheres obtained in Comparative Example 2 became an insulating material after expansion. This fully demonstrates the protective role of the double-layer conductive layer designed in Examples 1-3 on the conductive network during microsphere deformation. The unstable volume resistivity of the composite microspheres in Comparative Example 2 stemmed from its inelastic single-layer GO conductive layer. During polymerization, only the 3 and 4 positions of the 3,4-ethylenedioxythiophene monomer participate in the polymerization, resulting in a regular linear molecular chain that provides complete coating of the microsphere surface.

[0096] In Comparative Example 3, polyaniline was used instead of poly3,4-ethylenedioxythiophene to coat the expandable microspheres. However, the molecular chains of polyaniline are less regular and rigid than those of poly3,4-ethylenedioxythiophene, and the intermolecular forces are stronger, resulting in a lower degree of coating on the microspheres. In Comparative Example 4, hydroxyl carbon nanotubes were used instead of graphene oxide to coat the expandable microspheres. Hydroxyl carbon nanotubes, being linear materials, did not coat the expandable microspheres as effectively as sheet-like graphene oxide. Similarly, in Comparative Example 5, graphene oxide and polypyrrole were used instead of hydroxyl carbon nanotubes and poly3,4-ethylenedioxythiophene to coat the expandable microspheres, but the coating degree was far lower than that of the microspheres in Examples 1-3. Therefore, the initial resistance of the microspheres in Comparative Examples 3-5 was higher than that of the microspheres in Examples 1-3, and the resistance decayed more severely after heating.

[0097] It was also found that the composite microspheres could not expand at 80℃. As the temperature increased, the expansion of the expandable microspheres @GO@PEDOT composite microspheres increased to a greater extent. However, when the temperature reached 250℃, the structure of the microspheres was destroyed, rendering them unusable.

[0098] The above analysis proves that the present invention successfully coated graphene oxide (GO) and successfully grafted poly(3,4-ethylenedioxythiophene) (PEDOT) layer, and also proves that the prepared composite microspheres can fully maintain the conductive network structure on their surface during deformation.

[0099] Those skilled in the art should understand that the above description is merely a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing conductive expandable microsphere composite microspheres, characterized in that, The steps include the following: (a) Expandable microspheres and positively charged graphene oxide were added to water and mixed to obtain an expandable microspheres@GO dispersion. The dispersion was then allowed to stand, filtered, purified and dried to obtain conductive expandable microspheres@GO. (b) The expandable microspheres @GO obtained in step (a) were added to dichloromethane, a catalyst was added, and 3,4-thiophene dicarboxylic anhydride was added to react and expandable microspheres @GO-thiophene ester were prepared. (c) The expandable microspheres @GO-thiophene ester and 3,4-ethylenedioxythiophene monomer obtained in step (b) are added to chloroform and an initiator is added to react and obtain a conductive expandable microspheres @GO@PEDOT dispersion. (d) The conductive expandable microspheres @GO@PEDOT dispersion obtained in step (c) was allowed to stand, and then the upper solid was collected, purified, and dried to obtain conductive expandable microspheres @GO@PEDOT.

2. The method according to claim 1, characterized in that, In step (a), the mass ratio of expandable microspheres to positively charged graphene oxide is 10:0.5 to 2.0; in step (a), the mass ratio of expandable microspheres to water is 1:20 to 80.

3. The method according to claim 1, characterized in that, In step (b), the mass ratio of expandable microspheres @GO to dichloromethane is 1:8 to 15.

4. The method according to claim 1, characterized in that, The catalyst in step (b) is acetamide; the mass ratio of expandable microspheres @GO to catalyst in step (b) is 3:0.5-2.

5. The method according to claim 1, characterized in that, In step (b), the mass ratio of expandable microspheres @GO to 3,4-thiophene dicarboxylic anhydride is 30:1 to 8.

6. The method according to claim 1, characterized in that, In step (c), the mass ratio of expandable microspheres @GO-thiophene ester to 3,4-ethylenedioxythiophene monomer is 3:0.2 to 1.5; the mass ratio of expandable microspheres @GO-thiophene ester to chloroform in step (c) is 3:20 to 60.

7. The method according to claim 1, characterized in that, The initiator mentioned in step (c) is at least one of ammonium persulfate, potassium persulfate and ferric chloride; the mass ratio of expandable microspheres @GO-thiophene ester to initiator in step (c) is 100:1 to 5.

8. A conductive expandable microsphere prepared by the method according to any one of claims 1 to 7.

9. The application of the conductive expandable microspheres according to claim 8 in the fields of electromagnetic shielding, static electricity elimination, conductivity, intelligent sensing, aerospace, military defense, ships and vessels, and information communication.

10. The application of the conductive expandable microspheres of claim 8 in conductive fillers, characterized in that, The conductive expandable microspheres can be used alone or compounded with other materials and then mixed with polylactic acid or polyglycolic acid by melt processing, or with at least one of polyurethane dispersion, acrylic resin dispersion or epoxy resin dispersion by solution processing, to obtain a composite material with conductive or antistatic functions.

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