JP3066431B2 - Method for producing conductive polymer composite - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a conductive polymer composite, and more particularly to a method for combining a sulfonic acid and a polyaniline-based conductive polymer having excellent physical and chemical stability.

[0002]

2. Description of the Related Art Conductive polymers have attracted attention not only for their application as organic conductors and organic semiconductors, but also for their novel physical and electrochemical properties. They have attracted attention as batteries, display elements, photoelectric conversion elements, sensors, It is expected to be applied as a material for various functional elements such as an antistatic material, and as a functional material such as a nonlinear optical material, an antistatic material, and a radio wave absorbing material. Since it was found that the conductivity of polyacetylene was significantly increased by the ion doping method (Physics Review Letter, Vol. 39, Item 109, 1977), various ion-doping type conductive polymers have been proposed. I have. The doping includes P-type doping, in which a large number of holes are generated in the polymer by adding an electron acceptor (oxidizing agent), and N, in which many free electrons are generated in the polymer by adding an electron donor (reducing agent). There is type doping. P-type conductive polymer dopants can be as small as halogen ions, macrocyclic molecules, and even polymer electrolytes. Doping methods for these various dopants and the properties of the resulting conductive polymers And application development are attracting attention as new technologies.

[0003] Inorganic anions such as fluoride ions are often used as the above-mentioned dopants. These low molecular dopants can be doped in a large amount, but are easily moved in a conductive polymer and are easily desorbed by heating. However, there is a problem in stability as a material. In addition, such a conductive polymer composite doped with such a low molecular dopant generally has poor self-supporting properties and is brittle.

For this reason, it has recently been proposed to use a polymer electrolyte having an anion group as a dopant.
For example, JP-A-59-98165 proposes a conductive polymer composition using a polymer anion as a dopant. This composition includes, as dopants, sulfonated polyethylene, sulfonated polystyrene, sulfonated poly (2,5-dimethylphenylene oxide), sulfonated polyvinyl alcohol, and the like, and the anion group is formed from a sulfonic acid group. . This proposal is noteworthy because it shows that a conductive polymer composite that is stable and has good strength can be obtained as compared with a conventional conductive polymer using an inorganic anion as a dopant. However, since these are polymers, it is difficult to uniformly dope the interior of the conductive polymer, and the doping rate, which is an important factor for developing functionality such as conductivity, is low. There is.

On the other hand, research on oxidized polymers of aniline as an oxidation dye has been conducted for a long time, such as with aniline black. In particular, an octameric form of aniline, which is an intermediate for the production of aniline black, has been identified as emeraldine (see Journal of Chemical Society, 9
7, 2388 (1910); 101, 1117 (1912)), which is soluble in acetic acid, pyridine and DMF. Then, in recent years, it has also been found that this sulfate of emeraldine has high conductivity (Journal of Polymer Science, C, 16, 2931; 2943 (1967); 22, 1187 (1969)). More recently, it has been reported that emeraldine-like polyaniline obtained by chemical or electrochemical oxidative polymerization of aniline is easily doped with a protonic acid such as hydrochloric acid and exhibits high conductivity (Journal of Chemical Society, Chemical Communication, 1784 (198
7)).

[0006] Polyaniline is a conductive polymer that has recently attracted particular attention because it is stable in air and relatively easy to synthesize. However, since polyaniline has only a solubility that is slightly soluble in some polar solvents, it is disadvantageous in terms of workability required when applying a conductive polymer to various uses. The present inventors have found that in order to positively impart this processability, it is effective to introduce an alkoxy group or an alkyl group into the side chain of polyaniline and to solubilize the polyaniline (Japanese Patent Application Laid-Open No. 61-206106). issue). However, as in the case of the conductive polymer, there is no other method except for using a low molecular weight protonic acid to uniformly dope a large amount. Therefore, the above-mentioned problem remains in the stability in the doping state. Was.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyaniline-based conductive polymer excellent in physical and chemical stability, especially heat stability, in which a physically and chemically stable dopant is uniformly mixed. Is to provide a composite. More specifically, the present invention proposes a method of uniformly mixing a sulfonic acid-based polymer dopant having excellent stability with a polyaniline-based compound.

[0008]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above problems, and as a result, a polymerizable sulfonic acid which has high ionicity and can be polymerized after mixing has been converted into a polyaniline compound. Focusing on easy doping, the present inventors have found that by polymerizing these sulfonic acids after doping, a polymer dopant can be uniformly introduced into a polyaniline-based compound, and the present invention has been accomplished. Among the conductive polymers, polyaniline in particular has an amine and imine structure, so that it has a strong affinity for protonic acid and sulfonic acid can be easily doped. The present invention provides a conductive polymer, characterized in that the polymerizable acid polyaniline or a derivative thereof a repeating unit a structure represented by the following general formula (I) is doped, and then polymerizing the sulfonic acid The present invention relates to a method for producing a composite.

[0009]

Embedded image (In the formula, R ^{1 to} R ⁴ are a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, or an alkoxy group.)

Hereinafter, the present invention will be described specifically. Examples of the polyaniline derivative having a structure represented by the general formula (I) of the present invention as a repeating unit (hereinafter, “polyaniline derivative” includes polyaniline) include polyaniline, poly-o-toluidine, Poly-m-toluidine, poly-o-anisidine, poly-m-anisidine, polyxylysine, poly-2,5-dimethoxyaniline, poly-2,6-dimethoxyaniline, poly-2,5-diethoxyaniline, poly- 2,6-diethoxyaniline,
Examples thereof include poly-o-ethoxyaniline, poly-m-ethoxyaniline, and copolymers thereof, but are not particularly limited thereto. The larger the amount of the side chain introduced into the polyaniline derivative, the better in terms of solubility. However, if the amount is too large, steric hindrance and a decrease in molecular weight occur, which is not preferable in terms of electrical conductivity. Therefore, preferred derivatives include poly-o-anisidine, poly-m-anisidine, poly-2,5-dimethoxyaniline, poly-2,6-dimethoxyaniline, poly-anisidine,
o-ethoxyaniline and poly-m-ethoxyaniline.

The polymerization method for obtaining the polyaniline derivative of the present invention is not particularly limited, but generally, for example, Journal of Chemical Society, Chemical. As reported in Communication, 1784 (1987) and the like, a method is employed in which an aniline derivative such as aniline, o-anisidine, or 2,5-dimethoxyaniline is electrochemically or chemically oxidatively polymerized. .

The electrochemical oxidation polymerization is carried out by anodic oxidation. The current density is in the range of about 0.01 to 50 mA / cm ² , the electrolytic voltage is in the range of 0.1 to 30 V, and the constant current method, the constant voltage method and other methods are used. Any method can be used. The polymerization is carried out in an aqueous solution, an organic solvent or a mixed solvent thereof. The pH of the electrolytic solution is not particularly limited, but is preferably 3 or less, particularly preferably 2 or less. pH
Specific examples of the acid used for adjustment include HCl, HBF ₄ ,
Examples include strong acids such as CF ₃ COOH, H ₂ SO ₄ and HNO ₃ , and paratoluenesulfonic acid, but are not particularly limited thereto.

In the case of chemical oxidative polymerization, for example, the aniline derivative can be oxidatively polymerized with an oxidizing agent such as a peroxide or a persulfate in an acidic solution. As the acid used in this case, those similar to those used in the case of electrochemical oxidative polymerization are used, but are not limited thereto.

The molecular weight of the polyaniline derivative obtained by such a method is not particularly limited, but a molecular weight of 2000 or more is usually obtained. Further, the polyaniline derivative obtained by such a method is generally obtained in many cases in which anions in a polymerization solution are contained as dopants, and thus these anions are removed before adding the polymerizable sulfonic acid. Need to dope. The method of dedoping is not particularly limited, but a method of treating with a base such as aqueous ammonia is generally employed.

The polymerizable sulfonic acid of the present invention includes styrene sulfonic acid, vinyl sulfonic acid and derivatives thereof. Among them, p-styrenesulfonic acid is excellent in reactivity, stability and the like. The complex amount of the polyaniline derivative and the polymerizable sulfonic acid of the present invention is preferably such that the molar ratio of the sulfonic acid / monomer unit of the polyaniline derivative is 0.01 or more and 10 or less, more preferably 0.1 or less.
It is 1 or more and 2 or less. When the molar ratio is less than 0.01, the doping amount is small and there is no effect on improving the electric conductivity. On the other hand, if it is larger than 10, the amount of the sulfonic acid in the composite is too large, which impairs the electric conductivity of the conductive polymer.

The method of doping the polyaniline derivative of the present invention with a polymerizable sulfonic acid is not particularly limited, but a method of immersing a solid polyaniline derivative in a polymerizable sulfonic acid solution or a method in which the polyaniline derivative is soluble in a solvent. In such a case, a method of mixing the solutions is generally employed. In particular, when mixed in a solution state, there is a great advantage in processing such as film formation. The solvent in this case is not particularly limited as long as the polyaniline derivative can be dissolved. In addition, the temperature and time during the combination are not particularly limited. The affinity between the polyaniline derivative and the sulfonic acid is high.
What is necessary is just to stir and mix for about 30 minutes to 10 hours in the range of ° C.

In the present invention, it is characterized by polymerizing a sulfonic acid in the composite in After doped with polymerizable sulfonic acid polyaniline derivative. There is no particular limitation on the polymerization method, but if a catalyst is used, the residue may affect the electrical conductivity of the final composite and the like, and therefore a method of polymerizing in a non-catalytic system such as heating is preferred. The heating temperature and time in this case vary depending on the sulfonic acid used, but generally in the range of 150 ° C. to 250 ° C., 0.5 hour or more is required. The atmosphere for the heat treatment is preferably a state in which oxygen is discharged under reduced pressure or an inert atmosphere in order to prevent oxidative deterioration of the polyaniline derivative. Further, other substances having a catalytic action can be used in combination. The sulfonic acid polymer in the composite obtained in this way is 5 to
Many around 50 mer are formed.

[0018]

According to the present invention, a poly- or oligosulfonic acid-based dopant can be uniformly mixed into a polyaniline-based conductive polymer, and the conductive polymer composite is excellent in physical, chemical stability and workability. Is obtained. This method can be applied to various kinds of conductive polymers, and is extremely useful in application of conductive polymers such as constituent materials of various optoelectronic devices, antistatic materials, and radio wave absorbing materials.

[0019]

The present invention will be described in more detail with reference to the following examples. Example 1 A 1.5 mol HBF ₄ aqueous solution was placed in a glass reaction vessel 2
0 ml and 0.35 mol of 2,5-dimethoxyaniline were added to prepare an aqueous solution having a pH of <1.0. 2, each the electrode area at intervals of 2cm in the aqueous solution is 10 cm ²
After inserting the two platinum electrodes, an electric quantity of 20 coulombs was passed under stirring to carry out electrolytic oxidation polymerization. At this time, poly-2 doped with a dark green BF ₄ anion on the platinum electrode of the anode was used.
5-Dimethoxyaniline precipitated. Next, the precipitate was washed with 10% aqueous ammonia and then with distilled water, and turned into a deep blue color. After drying the polymer, it was peeled off from the platinum electrode and dissolved in N-methylpyrrolidone (NMP) to prepare a 2 wt% solution. The molecular weight of this solution determined by GPC measurement was about 100 in terms of polystyrene.
00.

Example 2 Sodium p-styrenesulfonate was dissolved in water and passed through an ion exchange resin to give 4 wt% of p-styrenesulfonate (P
SS) An aqueous solution was obtained. This solution was applied to a glass plate and heat-treated under reduced pressure at 150 ° C. for 2 hours. When the obtained film was redissolved in water, it showed strong acidity. GPC measurement of the film in an aqueous solution confirmed that a product having a molecular weight corresponding to a 5- to 20-mer of p-styrenesulfonic acid was formed.

Example 3 A 2 wt% poly-2,5-dimethoxyaniline NMP solution prepared in Examples 1 and 2 and a 4 wt% PSS aqueous solution were mixed so that each monomer ratio was 1: 1. A film is formed by spin coating (500 revolutions) on the
For about 8 hours under vacuum. The surface resistance (25 ° C., nitrogen atmosphere) of the obtained green film was 3 × 10 ⁶ Ω / □.
Next, after the above film was heat-treated at 150 ° C. for 2 hours, the surface resistance (25 ° C., nitrogen atmosphere) was measured, and the value was 4 × 10 ⁶ Ω / □. After standing for 1 week under the same conditions, the surface resistance (25 ° C., nitrogen atmosphere) was measured again. As a result, it was 4 × 10 ⁶ Ω / □, and the surface resistance hardly changed. It was confirmed that there was.

Example 4 A thermometer, a stirrer, and a condenser were attached to a 1 L four-necked flask, and 500 mL of a 1N aqueous HBF ₄ solution was added. 33.62 g of 2,5-dimethoxyaniline was added while bubbling nitrogen through. Dissolved. Then, 11.5 g of ammonium persulfate was added over about 30 minutes while stirring and while bubbling nitrogen through. Since this reaction is exothermic, it was kept at 22 ° C. by ice cooling during the reaction. After the addition, the reaction was further performed for 2 hours, followed by filtration.
Of distilled water. The product was then transferred to a beaker, washed with 500 mL of 5% aqueous ammonia with stirring for about 1 hour, filtered, and the residue was thoroughly washed with distilled water until the filtrate became neutral. By drying under reduced pressure for about 8 hours, an undoped poly-2,5-dimethoxyaniline powder was obtained by a chemical method. Further, this was dissolved in NMP to prepare a 2 wt% solution. GPC of this solution
The molecular weight determined by the measurement is about 80 in terms of polystyrene.
00.

Example 5 An NMP solution of 2 wt% poly-2,5-dimethoxyaniline prepared in Examples 4 and 2 and a 4 wt% PSS aqueous solution were mixed so that each monomer ratio was 1: 1. Immediately, a film was formed on a glass plate by spin coating (500 rotations) and vacuum dried at 50 ° C. for about 8 hours. The surface resistance (25 ° C., nitrogen atmosphere) of the obtained green film is 6 × 10 ⁶ Ω / □.
Met. Next, after the film was heat-treated at 150 ° C. for 2 hours, the surface resistance (25 ° C., nitrogen atmosphere) was measured, and the value was 7 × 10 ⁶ Ω / □. The composite membrane 100 ° C., 1 week after leaving under a nitrogen atmosphere, was measured surface resistance again (25 ° C., a nitrogen atmosphere), 7 × 10 ⁶
At Ω / □, the surface resistance hardly changed, and it was confirmed that the film was an electrically conductive film that was stable at high temperatures.

Examples 6 to 9 Example 4 was repeated except that equimolar amounts of aniline, o-toluidine, o-anisidine and o-ethoxyaniline were used in place of 2,5-dimethoxyaniline used in Example 4. The polymers shown in Table 1 corresponding to the respective monomers are chemically polymerized in the same manner as described above, and 1 to 2 wt% of NMP
A solution was prepared. The aniline polymer was only partially dissolved in NMP. Next, a composite was formed into a film in exactly the same manner as in Example 5 except that a solution of these polymers was used, and the surface resistance (25 ° C., nitrogen atmosphere) was measured. Was obtained, and the surface resistance hardly changed, confirming that the film was an electrically conductive film that was stable at high temperatures.

Example 10 In exactly the same manner as in Example 5 except that the solution was mixed such that the monomer ratio of 2,5-dimethoxyaniline: PSS was 2: 1 instead of the mixing ratio of the solution in Example 5. The composite is formed into a film by the method described above, and the surface resistance (25 ° C., nitrogen atmosphere)
As a result, the results as shown in Table 1 were obtained, and the surface resistance hardly changed, and it was confirmed that the film was an electrically conductive film that was stable at a high temperature.

Comparative Examples 1 and 2 Instead of the 4 wt% PSS aqueous solution used in Example 5, 4 w
A composite film was formed in exactly the same manner as in Example 5 except that a t% aqueous hydrochloric acid solution or a 4 wt% paratoluenesulfonic acid aqueous solution was used, and the surface resistance (25 ° C., nitrogen atmosphere) was measured. As a result, the sample was unstable at a high temperature.

[0027]

[Table 1]

Continuation of the front page (56) References JP-A-47-34539 (JP, A) JP-A-50-91700 (JP, A) JP-A-64-20202 (JP, A) JP-A-2-252733 (JP) JP-A-2-269163 (JP, A) JP-A-3-222207 (JP, A) JP-A-6-136264 (JP, A) "Macromolecules", Vol. 25, No. 7, 30. Mark h. 1992, p. 1959-1965 (58) Fields investigated (Int. Cl. ⁷ , DB name) C08L 79/00 C08G 73/00 C08F 2/44 C08F 283/00 CA (STN) REGISTRY (STN)

Claims (2)

(57) [Claims] 1. A general formula doped with polymerizable sulfonate polyaniline or its derivative and repeating units (I)
A method for producing a conductive polymer composite, comprising polymerizing sulfonic acid after the reaction. Embedded image (In the formula, R ^{1 to} R ⁴ are a hydrogen atom, an alkyl group having 1 to 10 carbon atoms or an alkoxy group.) 2. The method for producing a conductive polymer composite according to claim 1, wherein the polymerizable sulfonic acid is p-styrenesulfonic acid.