JP2011099010A - Production method for polythiophene, production method for polythiophene dispersion, polythiophene dispersion, and conductive film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for synthesizing a polythiophene by oxidation polymerization utilizing an oxidant in a catalyst amount, a dispersion containing the polythiophene, and a conductive film. <P>SOLUTION: The production method for a polythiophene is performed by subjecting a substituted thiophene such as 3,4-ethylenedioxythiophene to oxidation polymerization in the presence of a palladium-based catalyst such as palladium (II) acetate, a copper catalyst such as copper (II) acetate, and oxygen as an oxidant. The dispersion contains the polythiophene, palladium, and an aqueous polysulfonic acid solution. The conductive film is obtained from the dispersion. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing polythiophene, a method for producing a polythiophene dispersion, a polythiophene dispersion, and a conductive film.

Polythiophene has attracted attention as a functional polymer having electrical conductivity and light emission characteristics. In particular, poly (3-hexylthiophene) having a high positional order with head-to-tail is known to have a high charge transporting ability, and is applied to devices such as organic thin film transistors and polymer thin film solar cells. Is expected.
An oxidation polymerization reaction is an example of a method for synthesizing polythiophene by simple solution polymerization. For example, Patent Document 1 describes a method for producing a polythiophene dispersion in which 3,4-dialkoxythiophene or the like is oxidatively polymerized in the presence of a polyacid in the presence of a polyanion. Patent Document 2 describes a process for producing polythiophene in which a mixture of thiophene as a conductive polymer precursor and a strong acid, chlorate or chloric acid, iron salt, and reaction medium is reacted under polymerization conditions. Yes. Patent Document 3 describes a poly (dioxythiophene) / poly (acrylamide alkyl sulfonic acid) complex and an oxidative polymerization method for producing them.

Japanese Patent Application Laid-Open No. 07-90060 JP-T-2001-523741 JP-T-2005-508418

By the way, oxidative polymerization as a synthesis method of polythiophene requires an equivalent oxidizing agent such as iron (III) chloride. These oxidizing agents usually need to be removed during practical use. Even when the amount of the oxidizing agent used is reduced, it is necessary to further add an additive such as an oxidizing agent during the polymerization.
An object of the present invention is to provide a method for synthesizing polythiophene by oxidative polymerization using a catalytic amount of an oxidizing agent.

According to the present invention, there are provided a polythiophene production method, a polythiophene dispersion production method, a polythiophene dispersion, and a conductive film according to claims 1 to 14 below.
The invention according to claim 1 is a method for producing polythiophene, characterized in that thiophene is oxidatively polymerized in the presence of a palladium catalyst and an oxidizing agent.
The invention according to claim 2 is the method for producing polythiophene according to claim 1, wherein the palladium-based catalyst is palladium (II) acetate.
The invention according to claim 3 is the method for producing polythiophene according to claim 1 or 2, wherein the oxidizing agent is oxygen.

  The invention according to claim 4 is the method for producing polythiophene according to any one of claims 1 to 3, wherein the thiophene is a compound represented by the following formula (1).

(In Formula (1), R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, which may be substituted, Represents a C1-C8 dioxyalkylene group.)
The invention according to claim 5 is the method for producing polythiophene according to claim 4, wherein R ₁ and R ₂ in the formula (1) are selected from a hexyl group, a hexyloxy group, and an ethylenedioxy group. It is.
The invention according to claim 6 is the method for producing polythiophene according to any one of claims 1 to 5, further comprising using copper (II) acetate.

The invention according to claim 7 is a method for producing a polythiophene dispersion, wherein thiophene is oxidatively polymerized in an aqueous solution in the presence of a palladium-based catalyst, an oxidizing agent, and polysulfonic acid.
The invention according to claim 8 is the method for producing a polythiophene dispersion according to claim 7, wherein the polysulfonic acid is polystyrenesulfonic acid.
The invention according to claim 9 is characterized in that the thiophene is independently an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, and a carbon number at the 3rd and 4th positions of the thiophene skeleton. 9. The method for producing a polythiophene dispersion according to claim 7, wherein the polythiophene dispersion is a 3,4-disubstituted thiophene bonded with a 1 to 8 carbon dioxyalkylene group.
The invention according to claim 10 is the method for producing a polythiophene dispersion according to any one of claims 7 to 9, wherein the thiophene is 3,4-ethylenedioxythiophene.
The invention according to claim 11 is the polythiophene dispersion according to any one of claims 7 to 10, wherein the palladium-based catalyst is palladium (II) acetate and the oxidizing agent is oxygen. It is a manufacturing method of a body.

  The invention according to claim 12 is a polythiophene dispersion comprising polythiophene having a structural unit represented by the following formula (2), palladium, and an aqueous polysulfonic acid solution.

(In Formula (2), R ₁ and R ₂ are each independently a hydrogen atom, a C1-C8 alkyl group, a C1-C8 alkoxy group, which may be substituted, Represents a C1-C8 dioxyalkylene group.)
The invention according to claim 13 is the polythiophene dispersion according to claim 12, wherein R ₁ and R ₂ in the formula (2) are ethylenedioxy groups.

  The invention according to claim 14 is a conductive film obtained by forming the coating film of the polythiophene dispersion according to claim 12 or 13 on a predetermined substrate and drying the coating film. is there.

According to the present invention, polythiophene can be synthesized by using a trace amount of a palladium-based catalyst, as compared with conventional oxidative polymerization that requires an equivalent amount of oxidizing agent. This eliminates the need for a purification step for removing the oxidizing agent after the polymerization reaction is completed.
Moreover, the polythiophene dispersion containing the polysulfonic acid aqueous solution provides a polythiophene thin film having performance as a conductive film without going through a purification step.

2 is a ¹ H-NMR spectrum of poly (3-hexylthiophene) shown in Example 1. 6 is an IR spectrum of poly (3,4-ethylenedioxythiophene) shown in Example 5. It is a UV-visible absorption spectrum of the poly (3,4-ethylenedioxythiophene) thin film obtained in Examples 7 and 8. 6 is a diagram illustrating a method for preparing a poly (3,4-ethylenedioxythiophene) thin film obtained in Example 7. FIG.

  Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the invention.

<Method for producing polythiophene>
(Thiophene)
The thiophene used in the method for producing polythiophene to which the present embodiment is applied is, for example, a compound in which a hydrogen atom or a substituent is bonded to the 3-position and 4-position of the thiophene ring as represented by the following formula (1) Is mentioned.

Here, in Formula (1), R < ₁ > and R < ₂ > are respectively independently a hydrogen atom, the C1-C8 alkyl group which may be substituted, and a C1-C8 alkoxy. Group represents a C1-C8 dioxyalkylene group. R ₁ and R ₂ may be bonded to each other.
As a C1-C8 alkyl group which may be substituted, a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a pentyl group, an octyl group etc. are mentioned, for example. As a C1-C8 alkoxy group which may be substituted, a methoxy group, an ethoxy group, a propyloxy group, a hexyloxy group etc. are mentioned, for example. As a C1-C8 dioxyalkylene group which may be substituted, an ethylene dioxy group etc. are mentioned, for example.
Among these, a hexyl group, a methoxy group, a hexyloxy group, and a 3,4-ethylenedioxy group are preferable.

As the compound represented by the formula (1), the alkyl group having 1 to 8 carbon atoms, the alkoxy group having 1 to 8 carbon atoms, and the number of carbon atoms independently at the 3rd and 4th positions of the thiophene skeleton. A 3,4-disubstituted thiophene to which a 1 to 8 carbon dioxyalkylene group is bonded is preferred.
Specifically, for example, 3,4-dialkylthiophene, 3,4-dialkoxythiophene, 3,4-alkylenedioxythiophene and the like can be mentioned.
Specific examples of the compound include 3-hexylthiophene, 3,4-dihexylthiophene, 3,4-dimethoxythiophene, 3,4-dihexyloxythiophene, 3,4-methylenedioxythiophene, and 3,4-ethylene. Examples include dioxythiophene and 3,4-propylenedioxythiophene. Among these, 3,4-ethylenedioxythiophene is preferable.

(Palladium catalyst)
The palladium catalyst used in the present embodiment is not particularly limited. For example, the palladium catalyst is not particularly limited. For example, tetrakis (triphenylphosphine) palladium (0), tris (dibenzylideneacetone) dipalladium. (0), bis (tricyclohexyl) palladium (0), dichlorobis (triphenylphosphine) palladium (II), dibromobis (triphenylphosphine) palladium (II), dichloro [1,4-bis (diphenylphosphino) butane] Palladium (II), dichloro [1,2-bis (diphenylphosphino) ethane] palladium (II), dichloro [1,1′-bis (diphenylphosphino) ferrocene] palladium (II), palladium (II) acetate, etc. Is mentioned. Among these, palladium (II) acetate is preferable from the viewpoint of catalytic activity.

  Although the usage-amount of a palladium catalyst is not specifically limited, It is 0.005 equivalent-0.5 equivalent with respect to 1 mol of thiophene compounds shown by Formula (1), Preferably it is 0.01 equivalent-0.1 equivalent. When the amount of the palladium catalyst used is excessively small, the oxidative polymerization reaction tends to hardly proceed. Moreover, when the usage-amount of a palladium catalyst is too much, the effect corresponding to a usage-amount cannot be acquired and it is not economical.

(Copper catalyst)
In the present embodiment, it is preferable to use a copper catalyst in combination with the palladium catalyst. The copper catalyst is not particularly limited. For example, metal copper, cuprous chloride, cupric chloride, cuprous bromide, cupric bromide, cuprous iodide, cupric iodide, sulfate sulfate Cuprous, cupric sulfate, cuprous acetate, cupric acetate, cuprous formate, cupric formate, cuprous oxide, cupric oxide, copper (I) triflate, copper (I) methoxide , Copper (II) triflate, copper (II) methoxide, copper (II) acetylacetonate, copper (II) dipivaloylmethane, and the like. Among these, cupric chloride, cuprous iodide, and cupric acetate are preferable, and cupric acetate is more preferable.
Although the usage-amount of a copper catalyst is not specifically limited, It is 0.005 equivalent-0.5 equivalent with respect to 1 mol of thiophene compounds shown by Formula (1), Preferably it is 0.01 equivalent-0.1 equivalent. If the amount of copper catalyst used is excessively small, the degree of polymerization tends to be difficult to increase. Moreover, when there is too much usage-amount of a copper catalyst, there exists a tendency for the refinement | purification of the obtained polythiophene to become difficult.

(Oxidant)
The oxidizing agent used in the present embodiment is not particularly limited, and examples thereof include air or oxygen, iron (III) salts such as FeCl ₃ and Fe (ClO ₄ ) ₃ , organic acids, and inorganic acids containing organic residues. Iron (III) salt, H ₂ O ₂ , K ₂ CrO ₇ , alkali or ammonium persulfate, alkali perborate, potassium permanganate and copper salt, copper tetrafluoroborate and the like. In the present embodiment, air or oxygen is preferable.

(Polymerization solvent)
In the present embodiment, the thiophene oxidative polymerization is preferably performed by a solution polymerization method, a precipitation polymerization method, an emulsion polymerization method, a suspension polymerization method, or the like. Among these, the solution polymerization method is preferable.
Examples of the polymerization solvent that can be used for oxidative polymerization include chlorinated hydrocarbons such as chloroform, dichloromethane, 1,2-dichloroethane, chlorobenzene, dichlorobenzene, and trichlorobenzene; aromatics such as benzene, toluene, xylene, mesitylene, and diethylbenzene. Group hydrocarbons; ketones such as diethyl ether, tetrahydrofuran, dioxane, diglyme, anisole, acetone, methyl ethyl ketone, methyl isobutyl ketone, 2-heptanone, cyclohexanone, cyclopentane; esters such as methyl acetate, ethyl acetate, methyl lactate, ethyl lactate; Heterocyclic compounds such as γ-butyrolactone and γ-butyrolactam; N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, N-methylimidazoli Examples thereof include nitrogen-containing compounds such as dinone, pyridine and nitrobenzene; and sulfur-containing compounds such as carbon disulfide, nitromethane and dimethyl sulfoxide. Among these, chloroform, tetrahydrofuran, dichloromethane, toluene, pyridine and the like are preferable.

Furthermore, in this embodiment, in the thiophene oxidative polymerization, trifluoroacetic acid is used in combination with the polymerization solvent described above. By using trifluoroacetic acid together with the polymerization solvent, the polymerization rate and degree of polymerization can be increased.
Although the usage-amount of trifluoroacetic acid is not specifically limited, In this Embodiment, it is 5 mass%-50 mass% with respect to the polymerization solvent mentioned above, Preferably it is 10 mass%-20 mass%.
If the amount of trifluoroacetic acid used is too small, the degree of polymerization tends to be difficult to increase. In addition to trifluoroacetic acid, for example, methanesulfonic acid, trifluoromethanesulfonic acid, toluenesulfonic acid and the like can be used.

(Oxidative polymerization reaction of thiophene)
The production method of polythiophene to which the present embodiment is applied oxidizes the thiophene represented by the formula (1) in the presence of a palladium-based catalyst and an oxidizing agent according to the reaction scheme shown below under predetermined reaction conditions. Polythiophene is synthesized by polymerization.

When the oxidative polymerization of thiophene represented by formula (1) is performed by a solution polymerization method, the concentration of thiophene as a monomer in the polymerization solvent is usually 1% by mass to 50% by mass, preferably 3% by mass to 20% by mass. %, More preferably 5% by mass to 15% by mass.
The polymerization temperature for conducting the oxidative polymerization reaction is usually 0 ° C to 100 ° C, preferably 20 ° C to 80 ° C, more preferably 20 ° C to 50 ° C. The polymerization time is usually 1 hour to 48 hours, preferably 6 hours to 24 hours, more preferably 12 hours to 24 hours.
In the present embodiment, when oxygen is used as an oxidant in the oxidative polymerization of thiophene, for example, oxygen can be present in the polymerization reaction system by, for example, stirring the reaction solution in air to Examples thereof include a method for taking in the reaction solution and a method for blowing air or oxygen into the reaction solution.

(Polythiophene)
By the method for producing thiophene to which the present embodiment is applied, polythiophene having a structural unit represented by the following formula (2) is obtained.

Here, in the formula (2), _{R 1} and _{R 2} include those similar to _{R 1} and _{R 2} in Formula (1) described above.
Although the molecular weight of polythiophene is not particularly limited, in the present embodiment, the number average molecular weight (Mn) converted to standard polystyrene based on the measurement result of gel permeation chromatogram (GPC) is usually 1000 or more. Moreover, the molecular weight dispersion | distribution (Mw / Mn) calculated | required using the number average molecular weight (Mn) converted into standard polystyrene and the weight average molecular weight (Mw) is 1.5-4.0 normally.
Specific examples of polythiophene include, for example, poly (3-hexylthiophene), poly (3,4-dihexylthiophene), poly (3,4-dimethoxythiophene), poly (3,4-dihexyloxythiophene), poly ( 3,4-methylenedioxythiophene), poly (3,4-ethylenedioxythiophene), poly (3,4-propylenedioxythiophene) and the like. Among these, poly (3,4-ethylenedioxythiophene) is preferable.

<Method for producing polythiophene dispersion>
Next, a method for producing a polythiophene dispersion will be described. The method for producing a polythiophene dispersion to which the present embodiment is applied is that polythiophene exists in a dispersed state in an aqueous solution by oxidative polymerization of thiophene in an aqueous solution in the presence of a palladium-based catalyst, an oxidizing agent, and polysulfonic acid. A dispersion is produced.

(Polysulfonic acid)
Examples of the polysulfonic acid used in the present embodiment include polystyrene sulfonic acid and polyvinyl sulfonic acid. Among these, polystyrene sulfonic acid is preferable.
Although the molecular weight of polysulfonic acid is not specifically limited, For example, as a number average molecular weight, it is 1,000-2,000,000, Preferably it is 2,000-500,000.
Moreover, in this Embodiment, polycarboxylic acid can also be used in addition to polysulfonic acid or with polysulfonic acid. Examples of the polycarboxylic acid include polyacrylic acid, polymethacrylic acid, and polymaleic acid.
Polysulfonic acid is usually used in the form of an aqueous solution. The concentration of polysulfonic acid in the polysulfonic acid aqueous solution is not particularly limited, but is usually 5% by mass to 100% by mass, and preferably 10% by mass to 30% by mass.

(Oxidative polymerization reaction)
In the present embodiment, usually, an aqueous polysulfonic acid solution is prepared in advance, and a palladium-based catalyst, if necessary, and a copper catalyst are added to the aqueous solution to prepare an aqueous solution. Next, a thiophene represented by the formula (1) is added as a monomer to the aqueous solution to prepare a dispersion containing the thiophene monomer and the polysulfonic acid aqueous solution. Subsequently, thiophene is subjected to an oxidative polymerization reaction with air as an oxidizing agent in the atmosphere to produce a polythiophene dispersion.
Below, 3,4-ethylenedioxythiophene as thiophene, palladium (II) acetate as a palladium catalyst, copper acetate (II) as a copper catalyst, polystyrene sulfonic acid as polysulfonic acid, oxygen as an oxidizing agent, and oxidation in an aqueous solution The reaction scheme in the case of performing polymerization is shown.

In this Embodiment, the density | concentration of the thiophene represented by Formula (1) as a monomer in aqueous solution is 0.1 mass%-50 mass% normally, Preferably it is 0.5 mass%-10 mass%. Preferably they are 1 mass%-5 mass%.
The polymerization temperature for conducting the oxidative polymerization reaction is usually 0 ° C to 100 ° C, preferably 20 ° C to 80 ° C, more preferably 20 ° C to 50 ° C. The polymerization time is usually 1 hour to 48 hours, preferably 6 hours to 24 hours, more preferably 12 hours to 24 hours.
In the present embodiment, when oxygen is used as an oxidant in oxidative polymerization of thiophene in an aqueous solution, for example, oxygen can be present in the aqueous solution by, for example, stirring the aqueous solution in the air to Examples thereof include a method of incorporating into an aqueous solution and a method of blowing air or oxygen into the aqueous solution.

(Polythiophene dispersion)
A polythiophene dispersion is obtained by the above-described method for producing a polythiophene dispersion. In this Embodiment, the density | concentration of the polythiophene in a polythiophene dispersion is although it does not specifically limit, Usually, 0.5 mass%-10 mass%, Preferably, they are 1 mass%-5 mass%.
Although the density | concentration of palladium in a polythiophene dispersion is not specifically limited, Usually, 0.001 mass%-0.1 mass%, Preferably, they are 0.005 mass%-0.05 mass%.
The concentration of polysulfonic acid in the polythiophene dispersion is not particularly limited, but is usually 1% by mass to 30% by mass, and preferably 2% by mass to 10% by mass.
The concentration of the solid content in the polythiophene dispersion is not particularly limited, but is usually 0.5% by mass to 30% by mass, and preferably 1% by mass to 10% by mass.

<Conductive film>
The polythiophene dispersion to which this embodiment is applied can be formed into a film form by various methods and used as a conductive film. The film forming method is not particularly limited, and examples thereof include a casting method in which a polythiophene dispersion is spread on a flat substrate and moisture contained in the dispersion is evaporated to obtain a film.
In the present embodiment, the volume resistance of the conductive film thus obtained is 0.1Ω. cm to 10,000 Ω. cm.

  Hereinafter, the present embodiment will be described in more detail based on examples. The present embodiment is not limited to the following examples.

Example 1
<Synthesis 1 of poly (3-hexylthiophene)>
Into a two-necked flask, 0.421 g (2.5 mmol) of 3-hexylthiophene as a monomer, 55 mg (10 mol%) of palladium (II) acetate and 45 mg (10 mol%) of copper (II) acetate as a catalyst, The inside was replaced with oxygen as an oxidizing agent. Next, 5 ml of chloroform and 1 ml of trifluoroacetic acid were added, and the mixture was vigorously stirred at 50 ° C. for 24 hours to carry out an oxidative polymerization reaction of 3-hexylthiophene.
After completion of the reaction, the reaction solution was washed with water, and the organic layer was concentrated. The obtained polymer was washed with methanol and dried to obtain 0.164 g (yield 40%) of a black polymer.
It was confirmed that poly (3-hexylthiophene) was obtained by proton nuclear magnetic resonance ( ¹ H-NMR) spectrum measurement of the obtained polymer. The measurement result of ¹ H-NMR is shown in FIG. Moreover, as a result of measuring the obtained polymer by GPC, it was number average molecular weight 4,000 and molecular weight dispersion | distribution (Mw / Mn) 1.75 in standard polystyrene conversion.

(Example 2)
<Synthesis 2 of poly (3-hexylthiophene)>
In Example 1, the amount of catalyst used was changed to 5.5 mg (1 mol%) of palladium (II) acetate and 4.5 mg (1 mol%) of copper (II) acetate, and the reaction temperature was changed to 70 ° C. The oxidative polymerization reaction of 3-hexylthiophene was carried out under the same conditions as in Example 1.
After completion of the reaction, the reaction solution was washed with water, and the organic layer was concentrated. The obtained polymer was washed with methanol and dried to obtain 0.071 g (yield 17%) of a black polymer.
It was confirmed by the ¹ H-NMR measurement of the obtained polymer that poly (3-hexylthiophene) was obtained. Moreover, as a result of measuring the obtained polymer by GPC, it was number average molecular weight 2,000 and molecular weight dispersion | distribution (Mw / Mn) 1.91 in standard polystyrene conversion.

(Example 3)
<Synthesis of poly (3,4-dihexylthiophene)>
0.25 g (1 mmol) of 3,4-dihexylthiophene as a monomer, 22 mg (10 mol%) of palladium (II) acetate and 18 mg (10 mol%) of copper (II) acetate as a catalyst were placed in a two-necked flask, followed by a container. The inside was replaced with oxygen as an oxidizing agent. Next, 5 ml of chloroform and 1 ml of trifluoroacetic acid were added, and the mixture was vigorously stirred at 50 ° C. for 24 hours to carry out an oxidative polymerization reaction of 3-hexylthiophene.
After completion of the reaction, the reaction solution was washed with water, and the organic layer was concentrated. The obtained polymer was washed with methanol and dried to obtain 0.073 g (yield 29%) of a black polymer.
¹ H-NMR measurement of the obtained polymer confirmed that poly (3,4-dihexylthiophene) was obtained. Moreover, as a result of measuring the obtained polymer by GPC, it was number average molecular weight 1,000 and molecular weight dispersion | distribution (Mw / Mn) 1.88 in standard polystyrene conversion.

Example 4
<Synthesis of poly (3,4-dimethoxythiophene)>
Into a two-necked flask, 0.36 g (2.5 mmol) of 3,4-dimethoxythiophene as a monomer, 28 mg (5 mol%) of palladium (II) acetate and 23 mg (5 mol%) of copper (II) acetate as a catalyst, The inside of the container was replaced with oxygen as an oxidizing agent. Next, 5 ml of chloroform and 1 ml of trifluoroacetic acid were added, and the mixture was vigorously stirred at 50 ° C. for 24 hours to carry out oxidative polymerization reaction of 3,4-dimethoxythiophene.
After completion of the reaction, the reaction solution was washed with water, and the organic layer was concentrated. The obtained polymer was washed with methanol and then dried to obtain 0.272 g (yield 76%) of a black polymer.
It was confirmed by the ¹ H-NMR measurement of the obtained polymer that poly (3,4-dimethoxythiophene) was obtained. Moreover, as a result of measuring the obtained polymer by GPC, it was number average molecular weight 1,000 and molecular weight dispersion | distribution (Mw / Mn) 2.06 in standard polystyrene conversion.

(Example 5)
<Synthesis 1 of poly (3,4-ethylenedioxythiophene)>
3,1-ethylenedioxythiophene (0.71 g, 5 mmol) as a monomer, 11 mg (1 mol%) of palladium (II) acetate and 9 mg (1 mol%) of copper (II) acetate as a catalyst, The inside of the container was replaced with oxygen as an oxidizing agent. Next, 5 ml of chloroform and 1 ml of trifluoroacetic acid were added, and the mixture was vigorously stirred at 50 ° C. for 24 hours to carry out an oxidative polymerization reaction of 3,4-ethylenedioxythiophene.
After completion of the reaction, the reaction solution was washed with water, and the organic layer was concentrated. The obtained polymer was washed with methanol and then dried to obtain 0.071 g (yield 10%) of a black polymer.
It was confirmed by the infrared (IR) absorption spectrum measurement of the obtained polymer that poly (3,4-ethylenedioxythiophene) was obtained. The IR measurement results are shown in FIG.

(Example 6)
<Synthesis 2 of poly (3,4-ethylenedioxythiophene)>
In Example 5, the amount of the catalyst used was changed to 1.1 mg (0.1 mol%) of palladium (II) acetate and 0.9 mg (0.1 mol%) of copper (II) acetate, and otherwise, Example 5 The oxidative polymerization reaction of 3-hexylthiophene was performed under the same conditions as above.
After completion of the reaction, the reaction solution was washed with water, and the organic layer was concentrated. The obtained polymer was washed with methanol and then dried to obtain 0.062 g (yield 9%) of a black polymer.
It was confirmed by the ¹ H-NMR measurement of the obtained polymer that poly (3-hexylthiophene) was obtained.

(Example 7)
<Synthesis 1 of poly (3,4-ethylenedioxythiophene) dispersion>
In a flask, 10 g of polystyrenesulfonic acid aqueous solution (18 wt%) and 10 mL of distilled water were added, and then 11 mg (1 mol%) of palladium (II) acetate and 9 mg (1 mol%) of copper (II) acetate were added as catalysts. Prepared.
Next, 0.71 g (5 mmol) of 3,4-ethylenedioxythiophene is added to this aqueous solution as a monomer, and well dispersed using a homogenizer, and 3,4-ethylenedioxythiophene and an aqueous polystyrenesulfonic acid solution are added. A dispersion containing was prepared. Subsequently, the prepared dispersion was stirred at 300 rpm with a mechanical stirrer, and oxidative polymerization reaction of 3,4-ethylenedioxythiophene was performed with air as an oxidant under the conditions of 24 hours at 50 ° C. in the air. .

After completion of the reaction, the mixture was cooled to room temperature to obtain a deep blue poly (3,4-ethylenedioxythiophene) dispersion containing poly (3,4-ethylenedioxythiophene). The obtained dispersion remained stably dispersed for 6 months, and almost no precipitate was observed.
Furthermore, distilled water was added to this poly (3,4-ethylenedioxythiophene) dispersion to prepare a diluted solution (concentration 1% by weight). Subsequently, this diluted solution was spin-cast (1500 rpm, 30 seconds) on a glass substrate, and a coating film was formed on the glass substrate. Subsequently, this coating film was heat-treated at 200 ° C. for 1 hour to obtain a poly (3,4-ethylenedioxythiophene) thin film. It was 1260 ohm * cm as a result of measuring the volume resistance of the obtained thin film.
As a result of measuring the ultraviolet (UV) -visible absorption spectrum of the obtained thin film, broad absorption derived from absorption of poly (3,4-ethylenedioxythiophene) was observed in a wavelength region of 800 nm or more. FIG. 3 shows the UV-visible absorption spectrum of the poly (3,4-ethylenedioxythiophene) thin film. FIG. 4 is a view for explaining a method for preparing a poly (3,4-ethylenedioxythiophene) thin film.

(Example 8)
<Synthesis 2 of poly (3,4-ethylenedioxythiophene) dispersion>
In Example 7, the amount of the catalyst used was changed to 1.1 mg (0.1 mol%) of palladium (II) acetate and 0.9 mg (0.1 mol%) of copper (II) acetate. A dark blue poly (3,4-ethylenedioxythiophene) dispersion containing poly (3,4-ethylenedioxythiophene) by conducting an oxidative polymerization reaction of 3,4-ethylenedioxythiophene under the same conditions as Got.
Furthermore, a thin film of poly (3,4-ethylenedioxythiophene) was obtained by the same operation as in Example 7 using the obtained poly (3,4-ethylenedioxythiophene) dispersion.
It was 1630 ohm * cm as a result of measuring the volume resistance of the obtained thin film. Moreover, as in Example 7, the ultraviolet (UV) -visible absorption spectrum of the obtained thin film was measured, and as a result, it was derived from the absorption of poly (3,4-ethylenedioxythiophene) in the wavelength region of wavelength 800 nm or more. Broad absorption was observed. FIG. 3 shows the UV-visible absorption spectrum of the poly (3,4-ethylenedioxythiophene) thin film.

As described above in detail, in the method for producing polythiophene to which the present embodiment is applied, polythiophene is synthesized by using a trace amount of a palladium-based catalyst, as compared with oxidative polymerization using a conventional oxidizing agent. This eliminates the need for a purification step for removing the oxidizing agent after the polymerization reaction is completed.
In addition, a polythiophene thin film obtained using a polythiophene dispersion containing an aqueous polysulfonic acid solution without undergoing a purification step has performance as a conductive film.

  The polythiophene thin film obtained by the present invention can be applied to an antistatic film and an electronic device typified by organic EL.

Claims (14)

  A method for producing polythiophene, characterized in that thiophene is oxidatively polymerized in the presence of a palladium catalyst and an oxidizing agent.   The method for producing polythiophene according to claim 1, wherein the palladium-based catalyst is palladium (II) acetate.   The method for producing polythiophene according to claim 1 or 2, wherein the oxidizing agent is oxygen. The said thiophene is a compound represented by following formula (1), The manufacturing method of the polythiophene of any one of Claim 1 thru | or 3 characterized by the above-mentioned.

(In Formula (1), R ₁ and R ₂ are each independently a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, which may be substituted, Represents a C1-C8 dioxyalkylene group.) The method for producing polythiophene according to claim 4, wherein R ₁ and R ₂ in the formula (1) are selected from a hexyl group, a hexyloxy group, and an ethylenedioxy group.   Furthermore, copper acetate (II) is used, The manufacturing method of the polythiophene of any one of Claim 1 thru | or 5 characterized by the above-mentioned.   A method for producing a polythiophene dispersion, characterized in that thiophene is oxidatively polymerized in an aqueous solution in the presence of a palladium-based catalyst, an oxidizing agent, and polysulfonic acid.   The method for producing a polythiophene dispersion according to claim 7, wherein the polysulfonic acid is polystyrene sulfonic acid.   The thiophene is independently an alkyl group having 1 to 8 carbon atoms, an alkoxy group having 1 to 8 carbon atoms, or a dioxy having 1 to 8 carbon atoms at the 3-position and the 4-position of the thiophene skeleton. The method for producing a polythiophene dispersion according to claim 7 or 8, which is a 3,4-disubstituted thiophene having an alkylene group bonded thereto.   The method for producing a polythiophene dispersion according to any one of claims 7 to 9, wherein the thiophene is 3,4-ethylenedioxythiophene.   The method for producing a polythiophene dispersion according to any one of claims 7 to 10, wherein the palladium-based catalyst is palladium (II) acetate and the oxidizing agent is oxygen. Polythiophene having a structural unit represented by the following formula (2);
Palladium and
An aqueous polysulfonic acid solution,
A polythiophene dispersion comprising:

(In Formula (2), R ₁ and R ₂ are each independently a hydrogen atom, a C1-C8 alkyl group, a C1-C8 alkoxy group, which may be substituted, Represents a C1-C8 dioxyalkylene group.) The polythiophene dispersion according to claim 12, wherein R ₁ and R ₂ in the formula (2) are ethylenedioxy groups.   A conductive film obtained by forming a coating film of the polythiophene dispersion according to claim 12 or 13 on a predetermined substrate and drying the coating film.

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