Manufacturing method and application of conductive polypyrrole compound

Abstract

The invention discloses a preparation method and application of a conductive polypyrrole compound. The preparation method comprises the following steps: (1) preparing an emulsion system; (2) adding an oxidizing agent; (3) diluting and dropwise adding monomer pyrrole, and reacting for 6-24 hours; and (4) washing the product, and applying the product to preparation of the foamed conductive polyurethane foam. Comprising the following steps: 1, filtering a conductive polypyrrole compound; 2, carrying out synthesis post-treatment on the conductive polypyrrole compound; 3, effectively mixing the polypyrrole compound with a commercial polyurethane foaming component (firstly premixing with an isocyanate-containing component or a polyol-containing component, and then effectively mixing with another polyol-containing component or an isocyanate-containing component); and 4, carrying out one-time forming foaming to obtain the conductive product. The preparation method has the advantages that better dispersion can be realized by synthesizing the conductive polypyrrole compound which is microcosmically in a nano-scale dendritic shape, and the use amount of a conductive material is reduced; the foamed conductive polyurethane foam is simple and convenient to construct, can be foamed instantly, has high foaming rate, retains the original mechanical properties by more than 50%, and has good conductivity.

Description

Technical Field

[0001] The invention belongs to the technical field of conductive foams, and in particular relates to a preparation method and application of a conductive polypyrrole composite. Background Art

[0002] Polyurethane foam has the characteristics of high expansion rate, good impermeability, good sealing, corrosion resistance, light weight, good insulation to electricity and heat, etc. It is widely used in tunnels, mines for filling and anti-seepage, and to improve the strength of broken rock masses and as packaging materials for the electronic information industry. However, polyurethane foam has high surface resistance and volume resistance (for example, the volume resistivity is as high as 10 11 -10 13 Ω.cm), which easily generates static electricity and thus poses a great electrostatic safety hazard (for example, the static voltage generated can reach 3-4×10 3 V). Therefore, in the use environment, there are certain antistatic requirements for the material. For example, the polyurethane foam material used for packaging requires that the conductivity is not higher than 10 11 Ω.cm, while mines and tunnels adopt the standard MT113-1995, which requires the surface resistance to be less than 3.0×10 8 Ω.cm.

[0003] The main methods for modifying the antistatic properties of non-conductive polymer materials are coating with a conductive layer and adding conductive materials. The former, for foam plastics, primarily involves soaking and grafting the foam with a conductive solution to impart antistatic properties. For example, Yanbing Wang et al. (Chemistry of Materials; 2008) exposed pre-foamed polyurethane to an atmosphere of pyrrole monomers before chemically polymerizing it. This method is clearly unsuitable for on-site construction in tunnels, but it has little impact on small packaging materials. The latter method is relatively simple and primarily involves incorporating antistatic agents (such as quaternary ammonium salts, phosphate esters, hydrophilic organic polymers, and polyethylene oxide copolymers) or conductive fillers (such as conductive polymers and carbon-based materials such as carbon black, graphite, carbon nanotubes, and graphene). This method has been reported in the field of polyurethane foam materials (Jiang Zhiguo et al., Chemical Propellants and Polymer Materials; 2017), but with limited patent applications, industrial application remains a long way off. Antistatic foam plastics, especially conductive polyurethane foam materials that are suitable for mine tunnels and easy to construct, have not yet been reported. This may be because during the foaming process of polyurethane foam, due to compatibility, increased blending temperature, stretching and narrowing of the continuous phase, the effective contact surface (point) of the added conductive filler or antistatic agent is easily disconnected, and the conductive network is not easy to form. The foam plastic cannot meet the MT113-1995 antistatic requirements. For example, Tian Chunrong et al. (Liang Shuen et al., "Plastics Industry"; 2009) used conductive carbon black and hexadecyltrimethylammonium bromide as composite antistatic agents to prepare antistatic semi-rigid polyurethane whole skin foam. Conductive carbon black was evenly dispersed in the polyether component using a ball mill. When the amount of conductive carbon black added was greater than 3 parts, or when 1.5 parts or more of conductive carbon black was combined with 2.5 parts of hexadecyltrimethylammonium bromide, the volume resistivity of the material dropped to 10 8-9 Ω·cm; but continuing to increase the amount of conductive carbon black not only did not further reduce the resistivity of the material, but instead caused its resistivity to decrease slightly at the same order of magnitude. Analysis shows that it is difficult for carbon black particles to form a chain-like conductive path inside a material with a cellular structure. Only when the internal electric field between isolated carbon black particles is very strong can electrons jump across the interlayer barrier to generate field emission current. Bai Miao et al. (Bai Miao et al., "Guangzhou Chemical Industry"; 2013) used a combination of two antistatic agents and hexadecyltrimethylammonium bromide to prepare an antistatic polyurethane foam plastic, and the surface resistivity of the material can be reduced to 10 8Ω.cm. On the other hand, when antistatic agents are added to the foaming formula, they can often cause excessive material viscosity, making it difficult to handle. They can even cause problems such as merging and collapsing bubbles during foaming, as well as uneven and unstable antistatic properties, affecting foam performance. Jingcheng Wang et al. (Jincheng Wang et al., Journal of Elastomers and Plastics; 2009) added the antistatic agent AgIO3, cast the foam, and heat-cured it at 150°C for 3 hours to impart antistatic properties to the material. Xiangbing Xu et al. (Xiangbing Xu et al., Small; 2007) added carbon nanotubes to polyurethane foaming, achieving good antistatic effects. However, carbon nanotubes are relatively expensive, and their density differences can easily lead to uneven conductivity. Danqing Chen et al. (Danqing Chen et al., Composites Part a - Applied Science and Manufacturing; 2010) found that if graphene is added, the addition level needs to reach 12 wt%, and the amount of carbon black added is even higher.

[0004] In general, adding antistatic agent to the blend has a certain antistatic effect (surface resistivity is reduced to 10 8 -10 10 Ω.cm), but still cannot meet the MT113-1995 standard. Most of them also have problems such as decreased mechanical properties of modified materials, and the addition of other conductive materials easily leads to uneven dispersion and increased costs. The present invention can achieve true polyurethane foam conductivity (surface resistivity reduced to 10 6 -10 8 Ω.cm) and take into account the mechanical requirements. At the same time, the conductive foam can also be directly blended and foamed instantly at the construction site. Summary of the Invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for preparing and applying a conductive polypyrrole composite to realize instant foaming of conductive polyurethane foam.

[0006] In order to achieve the above-mentioned purpose of the invention, the present invention provides the following technical solution: a method for preparing a conductive polypyrrole composite, comprising the following steps: (1) preparing an emulsion system; (2) adding an oxidant; (3) diluting the monomer pyrrole and adding it dropwise to react for 6-24 hours; and (4) washing the product.

[0007] The emulsion system in step (1) adopts an emulsion synthesis method, including a water phase, an oil phase and an emulsifier, and the amount of the emulsifier is 1-3% w / v.

[0008] Furthermore, the oil phase of the emulsion is one or more of chloroform, dichloromethane, tetrahydrofuran, dioxane, and cyclohexane.

[0009] Furthermore, the emulsifier is one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, dodecylammonium chloride, octadecylammonium chloride, hexadecyltrimethylammonium bromide, and polyvinyl alcohol.

[0010] Furthermore, the ratio of the oil phase to the water phase is 70:30-50:50.

[0011] Furthermore, the oxidant in step (2) includes one or more of hydrogen peroxide, a divalent iron compound, or a trivalent iron compound, such as ferric dichloride or ferric chloride.

[0012] Furthermore, the solvent used for diluting the polymer monomer in step (3) is the same as the oil phase of the prepared emulsion system.

[0013] Furthermore, the monomer pyrrole feed ratio in step (3) accounts for 1-4% w / v of the solution.

[0014] Furthermore, in step (3), the molar ratio of the oxidant to the monomeric pyrrole is 2-2.3:1.

[0015] Furthermore, in step (4), the washing reagent is any one of water, alcohol, acetonitrile or a mixture thereof.

[0016] The morphology, structure, and surface chemistry of conductive polymers can be modified using appropriate emulsion and oxidation systems. The resulting modified materials can form nano-dendritic structures. Unlike the agglomerated strawberry-like polymer structures obtained by traditional synthesis methods, these nanostructures enable better dispersion, reduce the amount of conductive material used, lower the contact resistance between nanomaterials, and facilitate the formation of a conductive network within the polyurethane material.

[0017] Another object of the present invention is to provide an application of the conductive polypyrrole composite, namely, a method for preparing an instant conductive polyurethane foam. The method for preparing the instant conductive polyurethane foam comprises the following steps:

[0018] 1. Filtration of conductive polypyrrole composites;

[0019] 2. Post-synthesis treatment of the conductive polypyrrole composite, adjusting the humidity so that the solvent ratio is less than 50%;

[0020] 3. Effective premixing of the polypyrrole compound with a commercial isocyanate-containing component or a polyol-containing component;

[0021] Fourth, the commercial polyol component or the isocyanate-containing component is fully mixed with the product obtained in step three, and the conductive product is formed and foamed in one step.

[0022] In the step 4, the mixture is mixed by on-site mechanical blending and direct pouring, and the foaming temperature is 10° C.-50° C.

[0023] In summary, the present invention has the following beneficial effects: The advantages and positive effects of the present invention are: 1. Simple construction and instant foaming, and existing commercial polyurethane ingredients can be directly used; 2. High foaming rate, the foaming rate is more than 10 times, and can reach 80-90% of the original foaming rate; 3. The mechanical properties of polyurethane retain more than 50% of the original; 4. It has good electrical conductivity. When the conductive polymer content is only 3.5-5wt% (calculated based on the amount of monomer added), its volume resistivity can reach 10 6-7 Ω·cm, its conductive properties can meet the needs of anti-static foam plastics in defense, mining, tunnels and other fields. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Shown is a flow chart for making instant conductive polyurethane foam from conductive polypyrrole composites.

[0025] Figure 2 Shown are the reflectance infrared spectrum of the synthesized polypyrrole used in Example 2 (upper); and the thermogravimetric analysis TGA curve of the polypyrrole (lower).

[0026] Figure 3 Shown are the scanning electron microscope (SEM) image of the synthesized polypyrrole used in Example 3 (left); and the transmission electron microscope (TEM) image of the polypyrrole (right).

[0027] Figure 4 Shown are the thermogravimetric analysis TGA curves of the polyurethane foam without conductive polymer in Example 3 (top); and the thermogravimetric TGA analysis curves of the polyurethane foam containing conductive polymers of different components in the examples (bottom).

[0028] Figure 5 Shown is a scanning electron microscope (SEM) image of the conductive polyurethane foam in Example 3.

[0029] Figure 6 Shown is the compression mechanical curve of the conductive polyurethane foam in Example 3.

[0030] Figure 7 50-10 shown 7 Hz range, frequency-impedance Bode curve of the conductive polyurethane foam in Example 3. DETAILED DESCRIPTION

[0031] The following is combined with Figure 1-7The present invention will be further described in detail with the following embodiments:

[0032] Example 1

[0033] (1) Prepare the emulsion system: add 1g of sodium dodecylbenzenesulfonate to a mixed solution of 50ml of H2O and 50ml of CH3Cl3.

[0034] (2) Adding oxidant: Add 5.56 g of ferric chloride oxidant and stir for 0.5 hours to form a uniform solution.

[0035] (3) Dilute the monomer pyrrole and add it dropwise to react: 1 ml of monomer pyrrole is added to the solution and reacted for 24 hours to form a uniform black product, namely a conductive polypyrrole complex.

[0036] (4) Washing the product: The product is washed with methanol, water and methanol mixture until the washing liquid is colorless.

[0037] (5) Filter.

[0038] (6) Post-synthesis treatment of the conductive polypyrrole composite, adjusting the water content to less than 50%.

[0039] (7) The conductive polypyrrole complex obtained in step 6 is dispersed in commercial polyurethane.

[0040] (8) The commercial polyether polyol and the product obtained in step 3 are vigorously stirred and fully pre-mixed, and then mixed with another component containing isocyanate, and the conductive product is formed and foamed in one step to obtain a conductive product with a conductivity of 10 6-7 Ω·cm polyurethane foam.

[0041] Example 2

[0042] (1) Prepare the emulsion system: add 1 g of sodium dodecylbenzenesulfonate to a mixed solution of 40 ml of H2O and 60 ml of CH3Cl3.

[0043] (2) Adding an oxidant: Add 4.83 g of ferric chloride and 2 ml of 35% H2O2 and stir for 0.5 hours to form a uniform solution.

[0044] (3) Dilute the monomer pyrrole and add it dropwise: add 1 ml of monomer pyrrole to the solution and react for 24 hours to form a uniform black product.

[0045] (4) Washing the product: The product is washed with methanol, water and methanol mixture until the washing liquid is colorless.

[0046] (5) Filter.

[0047] (6) Post-synthesis treatment of the conductive polypyrrole composite, adjusting the water content to less than 50%.

[0048] (7) The conductive polypyrrole complex obtained in step 6 is dispersed in commercial polyurethane.

[0049] (8) The commercial polyether polyol and the product obtained in step 3 (50 wt%) were vigorously stirred and fully pre-mixed, and then mixed with another component containing isocyanate, and the conductive product was formed and foamed in one step to obtain a conductive product with a conductivity of 10 6-7 Ω·cm polyurethane foam.

[0050] Figure 2 The reflectance infrared spectrum of the synthesized polypyrrole used in Example (2) (top) is shown; the figure shows the characteristic absorption peaks of polypyrrole at different wavenumbers, with obvious absorption peaks at 1536cm-1, 1445cm-1, 1294cm-1, 1154cm-1, and 1037cm-1. The presence of these characteristic peaks helps to confirm the structure of polypyrrole. The thermogravimetric analysis (TGA) curve of polypyrrole (bottom) shows the thermal stability of polypyrrole. The dashed line represents the differential thermal analysis (DTA).

[0051] Example 3

[0052] (1) Prepare the emulsion system: add 2 g of sodium dodecylbenzenesulfonate to a mixed solution of 30 ml of H2O and 70 ml of CH2Cl2.

[0053] (2) Adding an oxidant: Add 9.6 g of ferric chloride and 2 ml of 35% H2O2 and stir for 0.5 hours to form a uniform solution.

[0054] (3) Dilute the monomer pyrrole and add it dropwise to react: 2 ml of monomer pyrrole was added to the solution and reacted for 24 hours to form a uniform black product.

[0055] (4) Washing the product: The product is washed with methanol, water and methanol mixture until the washing liquid is colorless.

[0056] (5) Filter.

[0057] (6) Post-synthesis treatment of the conductive polypyrrole composite, adjusting the water content to less than 50%.

[0058] (7) The conductive polypyrrole complex obtained in step 6 is dispersed in commercial polyurethane.

[0059] (8) The commercial polyether polyol and the product obtained in step 3 (30-40 wt%) were vigorously stirred and fully pre-mixed, and then mixed with another component containing isocyanate, and the conductive product was formed and foamed in one step to obtain a conductive product with a conductivity of 10 6-7 Ω·cm polyurethane foam.

[0060] Figure 3 Shown is a scanning electron microscope (SEM) image (left) of the synthesized polypyrrole used in Example 3. The SEM image shows the surface morphology of the polypyrrole material, showing a porous or dendritic structure. This structure is a nano- or micron-scale aggregate structure formed during the synthesis of polypyrrole. This nanostructure allows for better dispersion, reduces the amount of conductive material used, reduces the contact resistance between nanomaterials, and is more conducive to forming a conductive network in the polyurethane material. A transmission electron microscope (TEM) image (right) of the polypyrrole shows the polypyrrole in the form of nanoparticles or nanofibers. The SEM and TEM images of polypyrrole reveal its multi-scale structural features, from micron-scale dendritic or flower-like structures to nanoscale particles or fibers.

[0061] Figure 4 The top figure shows the TGA curve of the polyurethane foam without conductive polymer in Example 3; the bottom figure compares the TGA curves of polyurethane foams containing different conductive polymer components. The curves show the primary thermal decomposition process between approximately 200°C and 400°C.

[0062] Figure 5 Shown is a scanning electron microscope (SEM) image of the conductive polyurethane foam in Example 3. Specifically, the conductive polypyrrole complex is dispersed in different commercial polyurethanes, namely pure polyurethane (PU) and polyurethane foams containing different components of polypyrrole (PPy) (PU / PPy5, PU / PPy6, PU / PPy7). It can be concluded that 1. The influence of PPy: With the increase of PPy content (from PU / PPy5 to PU / PPy7), the surface roughness of PU foam gradually increases, the pore structure becomes more irregular, and the distribution of PPy particles in the matrix becomes denser, forming a more complete conductive network. 2. Performance improvement: The addition of PPy significantly improves the conductivity of PU foam and may also enhance its mechanical strength. This conductive polyurethane foam has broad application prospects in the fields of electromagnetic shielding, sensors, supercapacitors and battery electrodes. 3. Adaptability: According to specific application requirements, PU foams with different PPy contents can be selected. For example, applications requiring higher conductivity can choose samples with higher PPy content (such as PU / PPy7), while applications requiring a balance between conductivity and mechanical properties can choose samples with medium PPy content (such as PU / PPy6).

[0063] Figure 6Shown are compression mechanical curves for the conductive polyurethane foam in Example 3, including pure polyurethane (Control) and polyurethane foams containing different polypyrrole (PPy) components (PU / PPy5, PU / PPy6, and PU / PPy7). The mechanical properties of the polyurethanes retained over 50% of their original state.

[0064] Figure 7 50-10 shown 7 Hz range, the frequency-impedance Bode curve of the conductive polyurethane foam in Example 3 shows that the electrical performance of the conductive polyurethane is the best and the conductivity is 10 6-7 Ω·cm polyurethane foam.

[0065] This specific embodiment is merely an explanation of the present invention and is not intended to limit the present invention. After reading this specification, those skilled in the art may make non-creative modifications to this embodiment as needed. However, as long as such modifications are within the scope of the claims of the present invention, they are protected by patent law.

Claims

1. A method for preparing a conductive polypyrrole composite, characterized in that: The following steps are involved: (1) preparing an emulsion system; (2) adding an oxidant; (3) adding a diluted pyrrole monomer dropwise to react for 6-24 hours; (4) washing the product in a mixture of one or more of water, alcohol, and acetonitrile.

2. The method for preparing a conductive polypyrrole composite according to claim 1, wherein: The emulsion system in step (1) adopts an emulsion synthesis method, including a water phase, an oil phase and an emulsifier for synthesis in an amount of 1-3 wt / vol% and a ratio of oil phase:water phase of 70:30-50:

50.

3. The method for preparing a conductive polypyrrole composite according to claim 2, wherein: The oil phase of the emulsion is one or more of chloroform, dichloromethane, tetrahydrofuran, dioxane, and cyclohexane.

4. The method for preparing a conductive polypyrrole composite according to claim 2, wherein: The synthetic emulsifier is one or more of sodium dodecyl sulfate, sodium dodecyl sulfonate, sodium dodecylbenzenesulfonate, sodium dodecylbenzenesulfonate, dodecyl ammonium chloride, octadecyl ammonium chloride, hexadecyltrimethylammonium bromide, and polyvinyl alcohol.

5. The method for preparing a conductive polypyrrole composite according to claim 1, wherein: The oxidant described in step (2) includes one or more of hydrogen peroxide, divalent iron compounds, and trivalent iron compounds.

6. The method for preparing a conductive polypyrrole composite according to claim 1, wherein: The solvent used for diluting the polymer monomer in step (3) is the same as the oil phase of the emulsion system prepared in step (1).

7. The method for preparing a conductive polypyrrole composite according to claim 1, characterized in that: The monomer pyrrole feed ratio in step (3) accounts for 1-4% w / v of the solution.

8. The method for preparing a conductive polypyrrole composite according to claim 1, wherein: The molar ratio of the oxidant feed to the monomer pyrrole in step (3) is 2-2.3:

1.

9. An application of a conductive polypyrrole composite, characterized in that: The preparation of foamed conductive polyurethane foam comprises the following steps:

1. Filtration of conductive polypyrrole composites; 2. Post-synthesis treatment of the conductive polypyrrole composite, adjusting the humidity so that the solvent ratio is less than 50%; 3. Effective mixing of polypyrrole complexes with commercial isocyanate-containing components or polyol-containing components; Fourth, the commercial polyol component or the isocyanate-containing component is fully mixed with the product obtained in step three, and the conductive product is formed and foamed in one step at a foaming temperature of 10° C.-50° C.

10. The use of a conductive polypyrrole composite according to claim 9, characterized in that: The step 4 adopts the method of on-site mechanical mixing and direct pouring.

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