KR20070072017A - Mass fabrication method for preparing conductive polypyrrole nanoparticles using dispersion polymerization - Google Patents

Abstract

A massive production process of conductive polypyrrol nano-particles through dispersion polymerization is provided to produce the nano-particles with low production cost, short polymerization time and simple polymerization condition by preparing a dispersion of dispersion stabilizer and oxidation agent and adding pyrrol monomer to the dispersion to conduct dispersion polymerization. The process includes the steps of: dispersing a dispersion stabilizer in distilled water by adding the dispersion stabilizer to the distilled water and stirring the mixture to form the dispersion; adding an oxidation agent to the prepared dispersion and stirring the mixture to form a solution; dropping pyrrol monomer to the treated solution then polymerizing the mixture to form the completed solution; adding the distilled water to the completed solution to dissolve unreacted stabilizer and the oxidation agent in the solution and recovering conductive polymer nano-particles in a spherical form. The dispersion stabilizer is polyvinyl alcohol and used in an amount of 0.001-20 wt.% relative to total weight of the product.

Description

Mass fabrication method for preparing conductive polypyrrole nanoparticles using dispersion polymerization

1 is a Scanning Electron Microscope photograph of polypyrrole nanoparticles having a diameter of 63 nm prepared in Example 1 of the present invention;

2 is a Fourier transform infrared spectroscopy (FT-IR) graph of the polypyrrole nanoparticles prepared in Example 1 of the present invention;

3 is a transmission electron microscope (Transmission Electron Microscope) photograph of the polypyrrole nanoparticles prepared in Example 2 of the present invention.

The present invention provides a method for producing large quantities of conductive polypyrrole nanoparticles of several tens of nanometers in diameter using dispersion polymerization.

Nanotechnology is a technology to identify and control materials at the molecular and atomic level, and it is a technology that enables the transformation and modification of existing materials and the creation of new materials by combining atoms and molecules as appropriate, and is a key foundation for recent industrial and economic development of the next generation. It is recognized as alcohol.

Nanomaterials are generally 1-100 nanometers in size and exhibit new electronic, magnetic, optical, and electrical properties not found in solid state. Because of these properties, research on the manufacture of nanomaterials using metals, metal oxides, and inorganic materials has been continuously conducted. As a result, technologies for manufacturing nanometer-sized metal and inorganic semiconductor nanoparticles have been well established, and industrial applications are actively studied. It is becoming.

On the other hand, in the case of organic polymer nanomaterials, it is difficult to mass-produce and the production of nanoparticles having a uniform size is relatively complicated, thereby limiting the application range. Overcoming these limitations and increasing interest in researches for manufacturing and applying nanostructured materials of organic materials, researches for the production of nanostructured materials of conductive polymers have also been actively conducted.

In view of the electrically conductive material, the conductive polymer has a possibility of being used as a substitute for a heavy load, a transparent conductive film, an optical display element, an antistatic material, an electromagnetic shielding material, and the like. In order to enable this, not only high electrical conductivity but also improvement of workability, heat resistance, chemical resistance, and compatibility with commercial polymers are required. Recently, researches on improving the manufacturing method and improving the physical properties of well-known conductive polymers, such as polyaniline, polypyrrole, and polythiophene, which are excellent in stability, have been conducted, and are approaching the commercialization stage.

In addition to the above conditions, high yields, improved uniformity of particles, and mass production in grams have been required as essential elements for the practical application of conductive polymer nanomaterials, and their importance is increasing.

As a method for obtaining polypyrrole nanoparticles, studies have been conducted to form micelles using a surfactant such as octyltrimethylammonium bromide or tesyltrimethylammonium bromine, and then add and drop pyrrole monomer to polymerize it. However, this microemulsion polymerization method is limited in mass production because it involves a high manufacturing cost and a process for removing the surfactant used in the polymerization.

Therefore, there is a strong demand for a new production method capable of mass production while producing polypyrrole nanoparticles having excellent dispersibility and uniformity.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art, such as agglomeration of particles, nonuniformity in size, small amount of production, and technical problems that have been required in the past, and to provide an economical and convenient mass production method.

After numerous experiments and in-depth studies, the inventors have found a breakthrough method for obtaining nanometer-sized spherical materials through dispersion polymerization using a dispersion stabilizer that is different from the known methods. By using this preparation method, the experimental conditions for mass production of polypyrrole nanoparticles in a uniform size in a very simple manner in a short time were confirmed, and the present invention was achieved.

The present invention provides a method for producing polymer nanoparticles of several tens of nanometers in size using a dispersion polymerization method and an experimental method for improving uniformity and dispersibility in a manufacturing process and enabling mass production.

According to the invention the manufacturing process of the conductive polymer nanoparticles,

(A) adding a dispersion stabilizer to distilled water and stirring to disperse the dispersion stabilizer in distilled water;

(B) adding and stirring an oxidant to the aqueous solution in which the dispersion stabilizer is dispersed; And,

(C) polymerizing by dropping a pyrrole monomer in an aqueous solution in which the dispersion stabilizer and the oxidant are dispersed; And,

(D) distilled water is added to the solution after the polymerization to dissolve unreacted stabilizer and oxidizing agent to recover spherical conductive polymer nanoparticles.

Unless specifically stated in the specification, the numerical range of the content, size, temperature and the like means a range capable of optimizing the manufacturing method of the present invention.

In the method for preparing conductive polymer nanoparticles according to the present invention, a dispersion stabilizer is used to prevent entanglement of the polymer and limit the particle size to nanometer level to recover the organic polymer thus obtained through precipitation.

Dispersion stabilizers that can be used in step (A) are not specifically defined or limited, and include, but are not limited to, polyvinylalcohol, polyvinylacetate, polyvinylpyrrolidone, polyvinylmethylether And the like can all be used. However, polyvinyl alcohol is preferred for mass production and commercial purposes. The molecular weight of the dispersion stabilizer is also not particularly limited. However, it is preferable that the molecular weight of the dispersion stabilizer is too high so as not to interfere with the polymerization. If the molecular weight of the dispersion stabilizer is high, the dispersion effect is improved while precipitation of the prepared polymer particles is difficult. If the molecular weight is low, precipitation of the prepared polymer particles is easy. The concentration of the dispersion stabilizer in water is also not particularly limited and acts as a variable in the diameter of the polymer nanoparticles produced. If the concentration of the dispersion stabilizer is high, the size of the nanoparticles produced is small, and if the concentration of the dispersion stabilizer is low, the size of the polymer nanoparticles is made large. In addition, when the concentration of the dispersion stabilizer is high, the dispersibility is good, but it is difficult to separate the polymer nanoparticles from the mixed solution containing the polymer nanoparticles, and when the concentration of the dispersion stabilizer is low, the dispersibility is slightly decreased, but the separation of the polymer nanoparticles is easy. .

The oxidizing agent used in step (B) is an oxidizing agent capable of polymerizing monomers. Examples thereof include iron trichloride (FeCl ₃ ), copper dichloride (CuCl ₂ ), and ceric ammonium nitrate. It can be freely selected depending on the monomers and the polymerization temperature. Of these, iron trichloride is most preferred as an oxidizing agent for polymerizing the pyrrole monomer, and may be added 1 to 13 times based on the molar ratio of the pyrrole monomer. Theoretically, iron trichloride was added at 2.3 times the molar ratio of pyrrole monomers to provide an active site with 2 moles extending linearly, with 0.3 moles acting as a doping complex that acts as a dopant per 3 monomers. However, in the present invention, it is preferable to use an excess of oxidizing agent to prepare nano-sized conductive polymer particles.

The monomer used in step (C) is not particularly limited as long as it forms a spherical nanoparticle and is a monomer capable of dispersion polymerization, and typical examples thereof include pyrrole, thiophene, aniline, ethylenedioctylthiophene, and the like. Particularly preferred monomers are pyrrole monomers which provide polypyrrole which is a conductive polymer. The amount of monomer is preferably 0.1 to 0.5 moles with respect to water.

The time and temperature for the polymerization reaction may vary depending on monomers, dispersion stabilizers, oxidizing agents, and other reaction conditions. The polymerization time is about 1 minute to 2 hours, and the temperature is about −20 ° C. to 60 ° C.

In step (D), the dispersion stabilizer and the remaining oxidant are removed from the solution after polymerization, thereby obtaining a nanometer sized polymer spherical material. There is no particular limitation on the type and amount of the solvent for removing the dispersion stabilizer. Preferably, the dispersion stabilizer can be dissolved, and a solvent which is not toxic to the human body and is not environmentally harmful is preferable, and when polyvinyl alcohol is used as the dispersion stabilizer. Preferred solvent is distilled water.

The present invention relates to a method for mass production of polypyrrole nanoparticles by the above method.

Polypyrrole nanoparticles produced by the method of the present invention is characterized in that the size is uniform, spherical particles in the form of grams can be produced in large quantities. In addition, since the nano-sized polypyrrole particles are electrically conductive materials, they may be used as optical display materials, electromagnetic shielding materials, and antistatic materials. However, the polypyrrole nanoparticles according to the present invention can be applied and applied to various anticipated future applications without being limited to exemplary uses, and their use does not depart from the scope of the present invention.

EXAMPLE

Examples will be described below with reference to specific examples of the present invention, but the scope of the present invention is not limited thereto.

Example 1

150 mL of distilled water was added to a reaction vessel installed in a thermostat set at 25 ° C., and 0.5 g of poly (vinylalcohol: PVA) having an average molecular weight of 41,000 was added and dissolved as a dispersion stabilizer. 8.4 g of iron trichloride was added to the reaction vessel and stirred for 5 minutes at a rate of approximately 3,000 rpm. 1 g of pyrrole monomer ([pyrrole monomer]: [iron trichloride] = 1: 3.5) was injected into the pipette. After polymerization with stirring at 25 ° C. for 10 minutes, about 500 mL of distilled water was added to the reactor. This is to dissolve and remove the iron trichloride and polyvinyl alcohol used as a stabilizer did not participate in the reaction. After the reaction solution was transferred to a separatory funnel, polypyrrole nanoparticles were precipitated and separated from the mixed solution. The upper layer of distilled water was removed using a pipette to recover the precipitated polypyrrole nanoparticles. The process of precipitating polypyrrole nanoparticles by adding distilled water and removing the supernatant was repeated three times. The remaining lower layer was naturally evaporated at room temperature to obtain polypyrrole nanoparticles. As a result of analyzing the prepared polypyrrole nanoparticles using a scanning electron microscope, it was confirmed that spherical particles having an average of 53 nm were uniformly obtained as shown in FIG. 1. It was observed to have a conductivity of 8 S / cm using the four probe method, and also confirmed that the Fourier transform infrared spectroscopy (FT-IR) graph is polypyrrole as shown in FIG. 2.

Example 2

In order to determine the size change of the prepared polymer nanoparticles with respect to the amount of the dispersion stabilizer introduced in Example 1, the reaction conditions such as the reaction time, the stirring speed, and the amount of the monomer were kept constant and the amount of the dispersion stabilizer was 0.25 g. Experiment with increasing to 5 g. As the amount of dispersion stabilizer was increased, the average diameter of the prepared polypyrrole nanoparticles decreased from 60 nm to 30 nm and the degree of dispersion was gradually improved. When the amount of dispersion stabilizer is 0.25 g, 60 nm spherical nanoparticles are obtained, whereas 0.5 nm is 53 nm, 1.0 g is 50 nm, 2.0 g is 44 nm, and 3.0 g is 42 nm and 4.0. In the case of g, it was confirmed that spherical nanoparticles of 36 nm and 30 nm were prepared in the case of 5.0 g. Polypyrrole nanoparticles were prepared using 4.5 g of the dispersion stabilizer, and analyzed by transmission electron microscopy. As a result, it was confirmed that polypyrrole nanoparticles having an average diameter of 43 nm were formed, which is disclosed in FIG. 3.

Example 3

Using the same method as in Example 1, the amount of monomer, initiator, and dispersion stabilizer was left as it was, and the experiment was carried out by changing the molecular weight of the dispersion stabilizer to 41,000, 105,000, and 140,000. It was confirmed that when the molecular weight of the dispersion stabilizer was 41,000, spherical particles of 63 nm were obtained, whereas when the molecular weight was 105,000, an average of 52 nm and a molecular weight of 140,000, an average of 46 nm spherical particles were obtained uniformly.

Example 4

Experiment to change the amount of pyrrole monomer to 0.25 g, 0.5 g, 0.75 g, 1.0 g, 1.5 g, 2.0 g to determine the change in form and conductivity according to the pyrrole monomer injected using the same method as in Example 1 Proceeded. When the amount of pyrrole monomer is 0.25 g, an average of 43 nm spherical particles is obtained. When the amount of pyrrole monomer is 0.5 g, an average of 47 nm is obtained, when 1.0 g is an average of 53 nm, and when 1.5 g is an average of 56 nm and 2.0 g In the case of the average spherical particles of 59 nm was confirmed to be produced. Electrical conductivity was measured by four-probe method. The results are shown in Table 1 below.

Amount of pyrrole monomer Conductivity (S / cm) 0.5 0.92 0.75 1.65 1.0 8.04 1.5 14.65 2.0 43.37

As can be seen from Table 1, as the amount of pyrrole monomer injected was increased, the conductivity gradually increased to 43.37 S / cm.

Example 5

In order to determine the change according to the molar ratio of iron trichloride and pyrrole monomer using the same method as in Example 1, the experiment was carried out by changing to [iron trichloride] / [pyrrole] = 1.2, 2.3, 4.6, 6.9, 12.4. As the ratio of [iron trichloride] / [pyrrole] was increased, the size of the polypyrrole nanoparticles was similarly obtained on average from 50 nm to 53 nm.

Example 6

The experiment was carried out by changing the amount of distilled water to 100 ml, 150 ml, 200 ml, 250 ml, 300 ml using the same method as in Example 1. As a result of the transmission electron microscopy, the diameter of the prepared polypyrrole nanoparticle was 50 spherical particles having an average of 50 nm when the amount of distilled water was 100 ml, while the average was 53 nm at 150 ml and 55 nm, 250 at 200 ml. In the case of ml, it was confirmed that spherical particles having an average of 60 nm and 300 ml had an average of 70 nm.

Example 7

The experiment was conducted by changing the polymerization time of the pyrrole monomer into 1 minute, 5 minutes, 10 minutes, 1 hour, and 2 hours using the same method as in Example 1. As a result of transmission electron microscopy, it was confirmed that polypyrrole nanoparticles were successfully prepared within 1 minute.

Example 8

300 mL of distilled water was added to a 2 L reaction vessel, and 9 g of polyvinyl alcohol (poly (vinylalcohol): PVA) having a molecular weight of 41,000 was added and dissolved. 30 g of iron trichloride was added to the reaction vessel and stirred for 5 minutes at a speed of approximately 3,000 rpm. 1 g of a pyrrole monomer ([pyrrole monomer]: [iron trichloride] = 1: 12.4) was injected using a pipette and stirred for 10 minutes to polymerize. Phase without polyvinyl alcohol

Distilled water was further added, and the blend solution was prepared by changing the weight ratio of polypyrrole nanoparticles to 0.03, 0.15, 0.3, 0.6, and 2 weight ratios based on the total weight. The blend solution was spin coated once, twice and three times to vary the thickness to produce a conductive film. The transmittance of these films was measured using a UV / VIS spectrophotometer in the visible region, and the average transmittance according to the wavelength was confirmed. Among them, the transmittance of the conductive film having a weight ratio of polypyrrole nanoparticles at 0.03 and 0.3 weight ratio is shown in Table 2.

Polypyrrole amount (weight ratio) Spin coating count (times) Average transmittance (%)  0.03 One 97 2 95 3 94  0.3 One 82 2 69 3 56

Those skilled in the art to which the present invention pertains will be able to make various applications and modifications within the scope of the present invention based on the above contents.

The method for producing large amounts of uniform and dispersible polypyrrole nanoparticles on the order of tens of nanometers using the dispersion polymerization according to the present invention is a completely new method that has not been reported so far, and the manufacturing process is very simple and effective. The dispersion polymerization method using the dispersion stabilizer is economical, shorter reaction time than the conventional method, and enables mass production as well as uniform production of nano-sized materials. Conductive nanoparticles made through simple mass production according to the present invention are expected to contribute a great deal to the practical application to electronic materials.

Claims (11)

Adding a dispersion stabilizer to distilled water and stirring to disperse the dispersion stabilizer in distilled water; Adding and stirring an oxidizing agent into the aqueous solution in which the dispersion stabilizer is dispersed; And, Dropping and polymerizing a pyrrole monomer into an aqueous solution in which the dispersion stabilizer and the oxidant are dispersed; And, And distilled water is added to the polymerization solution to dissolve unreacted stabilizers and oxidants to recover spherical conductive polymer nanoparticles. The method of claim 1, wherein the diameter of the nanoparticles is controlled by changing the amount of polyvinyl alcohol as a dispersion stabilizer to 0.0001 to 20% by weight based on the total weight. The production method according to claim 1, wherein the molecular weight of polyvinyl alcohol, which is a dispersion stabilizer, is alternatively selected in the range of 1,000 to 500,000. The method according to claim 1, wherein the stirring speed is alternatively made in the range of 100 to 10,000 rpm. The method according to claim 1, wherein the amount of pyrrole monomer is alternatively made in the range of 0.001 to 30% by weight based on the total weight. The method according to claim 1, wherein the amount of distilled water is alternatively made in the range of 1 to 99% by weight based on the total weight. A process according to claim 1 wherein the polymerization time is from 1 minute to 24 hours. The production method according to claim 1, wherein the polymerization temperature is -20 to 100 ° C. The production method according to claim 1, wherein the molar ratio of iron trichloride and pyrrole is alternatively selected from [iron trichloride] / [pyrrole] = 0.1 to 20. 2. A process according to claim 1 wherein the mass production is possible by doubling the amount of reactants. A method for producing polypyrrole nanoparticles having a conductivity of 10 ^-2 to 10 ³ S / cm using a dispersion polymerization method using a dispersion stabilizer.

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