A polypyrrole film with double negative electromagnetic properties and its preparation method and application

Abstract

The present invention discloses a polypyrrole film with double negative electromagnetic properties and a preparation method and application thereof, belonging to the technical field of electromagnetic metamaterials. The present invention polymerizes pyrrole monomers on the interface formed after freezing an oxidant by a method of frozen interfacial polymerization, thereby obtaining a polypyrrole film with negative dielectric constant and magnetic permeability, and the frozen interface formed by freezing the oxidant provides a confined space for the polypyrrole film, thereby obtaining a light, thin, size- and structure-controllable polypyrrole film. The preparation method provided by the present invention has a simple process and low cost, can construct a complete planar molecular structure, and can obtain a separate polypyrrole film with double negative electromagnetic properties.

Description

Technical Field

[0001] The present invention belongs to the technical field of electromagnetic metamaterials, and in particular relates to a polypyrrole film with double negative electromagnetic properties and a preparation method and application thereof. Background Art

[0002] Polypyrrole is an intrinsically conductive polymer, which is widely used in electrode materials, semiconductors, sensors, optical absorbers, biomaterials and other fields. However, due to its insoluble and infusible characteristics, polypyrrole is difficult to reprocess and is usually presented in the form of powder or coating after mixing with a matrix. It is difficult to form an independent film for independent application. This means that when polypyrrole is used independently or in a mixed form, the mixing uniformity of the mixture and the conductivity of polypyrrole cannot be maximized, and thus it cannot be used to its maximum in some high-precision sensors, flexible circuits and efficient energy collection.

[0003] The intrinsic conductive polymer polypyrrole has electrical conductivity. Through process control, it can be used to prepare electromagnetic metamaterials with double negative electromagnetic properties. Therefore, it has great application prospects in the field of electromagnetic wave stealth and shielding. However, most polypyrroles are formed into conductive layers through surface polymerization, or conductive polymer powders are prepared through solution polymerization. In order to obtain polypyrrole with high conductivity, high sensitivity and even double negative electromagnetic properties, its preparation process and process parameters must be strictly controlled. Surface polymerization must be supported by a substrate, and the obtained polypyrrole coating is almost impossible to peel off from the substrate, that is, it is impossible to obtain a polypyrrole film alone.

[0004] Therefore, a method with simple process, low cost and the ability to obtain a separate polypyrrole film with double negative electromagnetic properties is urgently needed to solve the above problems. Summary of the invention

[0005] In order to solve the above technical problems, the present invention proposes a polypyrrole film with double negative electromagnetic properties and a preparation method and application thereof.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a polypyrrole film having double negative electromagnetic properties, comprising the following steps:

[0008] The oxidant solution is frozen to obtain an ice-like oxidant; the ice-like oxidant and the pyrrole solution are mixed and then subjected to freezing interfacial polymerization; and the polypyrrole film with double negative electromagnetic properties is obtained after thawing.

[0009] Preferably, the oxidant in the oxidant solution includes ferric chloride, ammonium persulfate, cupric chloride or hydrogen peroxide.

[0010] Preferably, the oxidant solution further comprises a polymer; the concentration of the oxidant in the oxidant solution is 0.2-3 mol / L, and the concentration of the polymer is 0-20 wt%.

[0011] Preferably, the polymer includes one or more of polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polyethylene oxide, water-soluble cellulose derivatives, and polyacrylic acid.

[0012] Preferably, the pyrrole solution further comprises a monomer linker; the concentration of pyrrole in the pyrrole solution is 0.2-3 mol / L, and the mass ratio of the monomer linker to pyrrole is 1:(10-300).

[0013] Preferably, the monomer linking agent includes one or more of 4,4'-biphenyldisulfonic acid, tetrasodium tetrasulfonate, and nickel phthalocyanine.

[0014] Preferably, the usage ratio of the icy oxidant and the pyrrole solution is (1-5):(1-3).

[0015] Preferably, the temperature of the frozen interface polymerization is -20 to 0°C, and the time of the frozen interface polymerization is 2 to 9 hours.

[0016] The present invention provides a polypyrrole film with double negative electromagnetic properties prepared by the preparation method described in the above technical solution, wherein the dielectric constant and magnetic permeability of the polypyrrole film are negative values.

[0017] The present invention also provides the application of the polypyrrole film with double negative electromagnetic properties described in the above technical solution in the fields of electromagnetic shielding, sensors, and intelligent touch conduction.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] The present invention uses a frozen interfacial polymerization method to polymerize pyrrole monomers on an interface formed after freezing an oxidant, and the growth of polypyrrole chains is restricted by the two-phase interface, and the growing polypyrrole chains are more likely to form a uniform and ordered two-dimensional network structure, thereby obtaining a polypyrrole film with negative dielectric constants and magnetic permeabilities, and the frozen interface formed by freezing the oxidant provides a restricted space for the polypyrrole film, thereby obtaining a light, thin, and structure-controllable polypyrrole film. The preparation method provided by the present invention has simple process and low cost, can construct a complete planar molecular structure, and can obtain a separate polypyrrole film with double negative electromagnetic properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0021] Figure 1 This is a schematic diagram of the process of preparing a polypyrrole film in Example 1;

[0022] Figure 2 Schematic diagram of the dielectric constant of the polypyrrole film prepared in Example 1;

[0023] Figure 3 Schematic diagram of the magnetic permeability of the polypyrrole film prepared in Example 1;

[0024] Figure 4 Schematic diagram of the conductive properties of polypyrrole cotton fabric, polypyrrole aramid and the polypyrrole film prepared in Example 1. DETAILED DESCRIPTION

[0025] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The embodiment of the present invention provides a method for preparing a polypyrrole film having double negative electromagnetic properties, comprising the following steps:

[0028] The oxidant solution is frozen to obtain an ice-like oxidant; the ice-like oxidant and the pyrrole solution are mixed and then subjected to freezing interfacial polymerization; and the polypyrrole film with double negative electromagnetic properties is obtained after thawing.

[0029] The present invention polymerizes pyrrole monomers on the interface formed after the oxidant is frozen through a frozen interface polymerization method, thereby obtaining a polypyrrole film with negative dielectric constant and magnetic permeability. The frozen interface formed by the freezing of the oxidant provides a confined space for the polypyrrole film, thereby obtaining a light, thin, size- and structure-controllable polypyrrole film.

[0030] In a preferred embodiment, the oxidant in the oxidant solution includes ferric chloride, ammonium persulfate, cupric chloride or hydrogen peroxide, more preferably ferric chloride or hydrogen peroxide; the ferric chloride is preferably FeCl3·6H2O. The present invention uses an oxidant to oxidize pyrrole monomers to generate polypyrrole.

[0031] In a preferred embodiment, the solvent of the oxidant solution is water; the concentration of the oxidant in the oxidant solution is 0.2-3 mol / L. The present invention controls the concentration of the oxidant within the above range to ensure the orderly growth of the polypyrrole molecular chain, and changing the concentration of the oxidant will obtain an over-oxidatively grown polypyrrole molecular chain.

[0032] In a preferred embodiment, the oxidant solution further comprises a polymer, and the concentration of the polymer in the oxidant solution is 0-20wt%. Too much polymer in the oxidant solution of the present invention will cause the polymerized polypyrrole molecular chains to agglomerate, thus affecting the performance of the film.

[0033] In a preferred embodiment, the polymer includes one or more of polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), polyacrylamide (PAM), polyethylene oxide (PEO), water-soluble cellulose derivatives, polyacrylic acid (PAA); the water-soluble cellulose derivative includes carboxymethyl cellulose (CMC) or hydroxyethyl cellulose (HEC). The polymer in the present invention is used to make the polymerized polypyrrole molecular chain form different forms.

[0034] In a preferred embodiment, the freezing time is 10-12 hours.

[0035] In a preferred embodiment, the solvent of the pyrrole solution is cyclohexane; the concentration of pyrrole in the pyrrole solution is 0.2-3 mol / L. The present invention controls the concentration of pyrrole within the above range, which promotes the full progress of the polymerization reaction. Changing the concentration of pyrrole will affect the polymerization rate and lead to irregular growth of polypyrrole molecular chains.

[0036] In a preferred embodiment, the pyrrole solution further comprises a monomer linker; the mass ratio of the monomer linker to pyrrole in the pyrrole solution is 1:(10-300). Too much monomer linker in the pyrrole solution of the present invention will aggregate on the polypyrrole molecular chain, affecting the performance of the film.

[0037] In a preferred embodiment, the monomer linking agent includes one or more of 4,4'-biphenyldisulfonic acid, tetrasodium tetrasulfonate, and nickel phthalocyanine. The monomer linking agent in the present invention is used to connect pyrrole monomers to form a three-dimensional network structure.

[0038] In a preferred embodiment, the usage ratio of the icy oxidant and the pyrrole solution is (1-5):(1-3).

[0039] In a preferred embodiment, the method of mixing the icy oxidant and the pyrrole solution includes pouring the pyrrole solution onto the icy oxidant or placing the icy oxidant in the pyrrole solution.

[0040] In a preferred embodiment, the temperature of the frozen interface polymerization is -20 to 0°C, and the time of the frozen interface polymerization is 2 to 9 hours. The present invention controls the temperature and time of the frozen interface polymerization within the above range, thereby improving the growth stability of polypyrrole. Too high a temperature or too short a time is not conducive to the formation of a polypyrrole film, and too long a time will result in too many polypyrrole branches and affect the electromagnetic properties of the film.

[0041] In a preferred embodiment, the thawing method is room temperature thawing or hot water thawing.

[0042] The present invention provides a polypyrrole film with double negative electromagnetic properties prepared by the preparation method described in the above technical solution, wherein the dielectric constant and magnetic permeability of the polypyrrole film are negative values.

[0043] In a preferred embodiment, the polypyrrole film has a thickness of 10-50 μm and an ordered two-dimensional polypyrrole network structure.

[0044] In a preferred embodiment, the polypyrrole film is composed of pure polypyrrole without any other carrier, including a base layer or a mixture.

[0045] The present invention also provides the application of the polypyrrole film with double negative electromagnetic properties described in the above technical solution in the fields of electromagnetic shielding, sensors, and intelligent touch conduction.

[0046] The room temperature in the embodiments of the present invention refers to "25±2°C".

[0047] Unless otherwise specified, the raw materials in the examples of the present invention were purchased from commercial sources.

[0048] Example 1

[0049] Dissolve FeCl3·6H2O in water to obtain a FeCl3 solution with a concentration of 0.2 mol / L, then pour it into a smooth vessel and freeze it for 12 hours to form a smooth ice surface, which is an ice-like oxidant. Dissolve pyrrole in cyclohexane to obtain a pyrrole solution with a pyrrole concentration of 0.2 mol / L, then pour the pyrrole solution on the ice surface and freeze the interface at -20°C for 8 hours. After the reaction is completed, thaw at room temperature, take out the polypyrrole film, and repeatedly clean it with anhydrous ethanol and distilled water, and dry it to obtain a 20 μm thick polypyrrole film with double negative electromagnetic properties.

[0050] Figure 1 Schematic diagram of the process of preparing polypyrrole film in Example 1. Figure 1 It can be seen that a polypyrrole film is obtained by pouring a pyrrole solution made of a mixture of pyrrole and cyclohexane onto an ice surface formed after the FeCl3 solution is frozen.

[0051] Figure 2Schematic diagram of the dielectric constant of the polypyrrole film prepared in Example 1. Figure 2 It can be seen that in the range of 1 MHz-1 GHz, the dielectric constants of the polypyrrole film prepared in Example 1 are all negative.

[0052] Figure 3 Schematic diagram of the magnetic permeability of the polypyrrole film prepared in Example 1. Figure 3 It can be seen that in the range of 1 MHz-1 GHz, the magnetic permeability of the polypyrrole film prepared in Example 1 is negative.

[0053] Figure 4 Schematic diagram of the conductive properties of polypyrrole cotton fabric, polypyrrole aramid and polypyrrole film prepared in Example 1. Figure 4 It can be seen that the resistance of the polypyrrole film prepared in Example 1 of the present invention is only 333.3Ω, which is significantly reduced compared with the resistance of the polypyrrole cotton fabric (1588.0Ω) and the resistance of the polypyrrole aramid (1190.3Ω), indicating that the polypyrrole film prepared in Example 1 of the present invention has excellent conductive properties; wherein, the polypyrrole cotton fabric is sourced from the local market, and the polypyrrole aramid is sourced from the local market.

[0054] Example 2

[0055] FeCl3·6H2O and PVA were dissolved in water to obtain a mixed solution with a FeCl3 concentration of 1 mol / L and a PVA concentration of 10 wt%, which was then poured into a smooth vessel and frozen for 12 hours to form a smooth ice surface, which was an ice-like oxidant. Pyrrole, 4,4'-biphenyl disulfonic acid and cyclohexane were mixed evenly to obtain a pyrrole solution with a pyrrole concentration of 1 mol / L, wherein the mass ratio of pyrrole to 4,4'-biphenyl disulfonic acid was 10:1, and then the pyrrole solution was poured on the above ice surface and frozen at -10°C for 6 hours for interfacial polymerization. After the reaction was completed, it was thawed at room temperature, the polypyrrole film was taken out, and it was repeatedly cleaned with anhydrous ethanol and distilled water, and dried to obtain a polypyrrole film with a thickness of 25 μm and double negative electromagnetic properties.

[0056] Example 3

[0057] FeCl3·6H2O and PEO were dissolved in water to obtain a mixed solution with a FeCl3 concentration of 1 mol / L and a PEO concentration of 15 wt%, which was then poured into a square glass container and frozen for 12 hours to obtain a square ice cube with smooth sides, i.e., an ice-like oxidant. Pyrrole, tetrasodium tetrasulfonate and cyclohexane were mixed evenly to obtain a pyrrole solution with a pyrrole concentration of 2 mol / L, wherein the mass ratio of pyrrole to tetrasodium tetrasulfonate was 50:1, and then the square ice cube was placed in the pyrrole solution (the volume ratio of ice cube to pyrrole solution was 1:2), and the interfacial polymerization was performed at -5°C for 3 hours. After the reaction was completed, the solution was thawed at room temperature, the polypyrrole film was taken out, and it was repeatedly cleaned with anhydrous ethanol and distilled water, and dried to obtain a square polypyrrole film with a thickness of 15 μm and double negative electromagnetic properties.

[0058] Example 4

[0059] Hydrogen peroxide and hydroxyethyl cellulose are dissolved in water to obtain a mixed solution with a hydrogen peroxide concentration of 2 mol / L and a hydroxyethyl cellulose concentration of 20 wt%, which is then poured into a round glass container and frozen for 10 hours to obtain round ice cubes with smooth surfaces, i.e., ice-like oxidants. Pyrrole, nickel phthalocyanine and cyclohexane are mixed evenly to obtain a pyrrole solution with a pyrrole concentration of 3 mol / L, wherein the mass ratio of pyrrole to nickel phthalocyanine is 100:1, and then the round ice cubes are placed in the pyrrole solution (the volume ratio of ice cubes to pyrrole solution is 1:3), and the interfacial polymerization is performed at 0°C for 3 hours. After the reaction is completed, the mixture is thawed at room temperature, the polypyrrole film is taken out, and it is repeatedly cleaned with anhydrous ethanol and distilled water, and dried to obtain a round polypyrrole film with a thickness of 30 μm and double negative electromagnetic properties.

[0060] Comparative Example 1

[0061] The difference from Example 1 is that FeCl3·6H2O is dissolved in water to prepare a FeCl3 solution with a FeCl3 concentration of 0.05 mol / L, and the remaining steps are the same as Example 1.

[0062] Comparative Example 2

[0063] The difference from Example 1 is that pyrrole is dissolved in cyclohexane to prepare a pyrrole solution with a pyrrole concentration of 0.05 mol / L, and the remaining steps are the same as Example 1.

[0064] Comparative Example 3

[0065] The difference from Example 1 is that the interfacial polymerization is carried out at -25°C for 8 hours, and the remaining steps are the same as Example 1.

[0066] The resistance of the polypyrrole films prepared in Comparative Examples 1-3 is shown in Table 1, and the test temperature is 25°C.

[0067] Table 1 Resistance of polypyrrole films prepared in Example 1 and Comparative Examples 1-3

[0068]

[0069]

[0070] It can be seen from Table 1 that the resistance of the polypyrrole films prepared in Comparative Examples 1-3 is greater than that of the polypyrrole film prepared in Example 1.

[0071] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for preparing a polypyrrole film having double negative electromagnetic properties, characterized in that: The following steps are involved: Freezing the oxidant solution to obtain an ice-like oxidant; mixing the ice-like oxidant and the pyrrole solution to perform freeze-interfacial polymerization, and thawing to obtain the polypyrrole film with double negative electromagnetic properties; The oxidant solution also includes a polymer; the concentration of the oxidant in the oxidant solution is 0.2 mol / L, and the concentration of the polymer is 0-20 wt%; The pyrrole solution also includes a monomer linker; the concentration of pyrrole in the pyrrole solution is 0.2 mol / L, and the mass ratio of the monomer linker to pyrrole is 1:(10-300); The temperature of the frozen interface polymerization is -20 to 0°C, and the time of the frozen interface polymerization is 8 to 9 hours.

2. The preparation method according to claim 1, characterized in that: The oxidant in the oxidant solution includes ferric chloride, ammonium persulfate, cupric chloride or hydrogen peroxide.

3. The preparation method according to claim 1, characterized in that: The polymer includes one or more of polyvinyl alcohol, polyvinyl pyrrolidone, polyacrylamide, polyethylene oxide, water-soluble cellulose derivatives, and polyacrylic acid.

4. The preparation method according to claim 1, characterized in that: The monomer linking agent includes one or more of 4,4'-biphenyldisulfonic acid, tetrasodium tetrasulfonate, and nickel phthalocyanine.

5. The preparation method according to claim 1, characterized in that: The volume ratio of the ice-like oxidant to the pyrrole solution is (1-5):(1-3).

6. The polypyrrole film with double negative electromagnetic properties prepared by the preparation method according to any one of claims 1 to 5, characterized in that: The dielectric constant and magnetic permeability of the polypyrrole film are negative values.

7. Application of the polypyrrole film with double negative electromagnetic properties as claimed in claim 6 in the fields of electromagnetic shielding, sensors, and intelligent touch conduction.

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