JPS614739A - Porous electrolytic polymer film and its preparation - Google Patents

Abstract

PURPOSE:To obtain the titled film having a thicknesswise unsymmetrical constitution and excellent electrical conductivity, by the electrolytic polymerization of an aromatic compound on an electrode having a polymer film adhering thereto to form a composite with the film, followed by removal of the film polymer by extraction. CONSTITUTION:An insulating polymer film such as a PVC resin film is sticked to an electrode prepared by depositing a conductive metal oxide such as indium oxide on a base plate such as a glass plate to give an electrode having a polymer film adhering thereto. This electrode and a counter electrode are immersed in an electrolyte solution prepared by dissolving an aromatic compound (e.g. pyrrole) and an electrolyte such as an organic quaternary ammonium salt in an acetonitrile solvent to cause to undergo electrolytic polymerization, allowing the electrolytic polymer of the aromatic compound aforementioned (e.g. a polypyrrole) to form a composite with the polymer film. This composite film is stripped off from the base plate and only the polymer film is removed by extraction to give the titled film which has a densely deposited electrolytic polymer on one side and a porous constitution on the other side and inside.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a new porous polymer film that can be used for various separation membranes, etc., and a method for producing the same. Methods of manufacturing include using a foaming agent, creating a resin film gel and removing the solvent etc. from the gel, and mixing a filler with the resin.
A method is known in which the photonic agent is removed after the film is formed. Such porous films are expected to be in great demand as separation membranes for gases, liquids, ions, etc. In order to improve the separation performance of a separation membrane, a porous film having an asymmetric structure in the thickness direction is required. In other words, one surface has a relatively dense structure, and gas,
It is desirable that the film has a high separation ability for liquids, ions, etc., and that the inside and back surface of the film are porous so that separated molecules of gas, liquid, ions, etc. can easily pass through.

[Problem that the invention seeks to solve]

However, it has been difficult to obtain a porous film with such a structure using conventional methods.

In recent years, research on conductive polymer films such as polyacetylene and polypyrrole has become active. In particular, polyacetylene films are fibrous and provide a type of porous film with a large surface area.

This porosity makes it easy to incorporate large amounts of ions, and electrochemical doping of ions changes the electrical conductivity, so it is attracting attention as a film-like battery material, but it is difficult to obtain an asymmetric porous film. difficult.

On the other hand, certain aromatic compounds such as virol and thiophene are known to provide conductive polymer films on electrodes through electrolytic polymerization.

The present inventors have already developed a method for obtaining a new conductive polymer film by electrochemically compounding an electrolytic polymer of an aromatic compound into an insulating polymer film (Japanese Patent Application No. 58-186991) No. 58-215201, No. 5
8-2' No. 15204).

In other words, a conductive polymer film produced by electrolytic polymerization is usually produced by placing an electrode substrate together with a counter electrode in a solution containing an aromatic compound as a monomer for electrolytic polymerization and an electrolyte for conducting electricity in an organic solvent such as acetonitrile. It is formed by applying current between the two electrodes. At this time, if the electrode substrate is coated with an insulating polymer film,
Naturally, electricity cannot be passed and no conductive film is formed. However, the present inventors have already shown that by coating various polymer films on electrode substrates and combining them with an appropriate electrolytic reaction solution that does not dissolve the films, the electrolytic reaction proceeds in the same way as on ordinary electrodes. I found it.

The structure and mechanical properties of conductive polymer films such as polypyrrole and polythiophene differ depending on the conditions of electrolytic polymerization, but they usually have a uniform structure.
It is difficult to obtain asymmetric porous films.

An object of the present invention is to eliminate the conventional drawbacks and provide a conductive porous film with an asymmetric structure and a method for producing the same.

[Means for solving problems]

To summarize the present invention, the first invention relates to a porous electrolytic polymer film, which is an electrolytic polymer film of an aromatic compound, and is characterized in that it is porous.

A second invention of the present invention relates to a method for producing a porous electrolytic polymer film, which includes a step of closely adhering a polymer film to an electrode, and electrolytically polymerizing an aromatic compound on the film-attached electrode. The method is characterized in that it includes the following steps: a step of compounding the polymer of the aromatic compound into the polymer film, and a step of extracting and removing the polymer film from the composite film.

The conductive polymer film obtained by the above-described method developed by the present inventors is a mixture of an electrolytic polymer of an aromatic compound and an insulating polymer film material, and they have chemical bonds with each other. That is not confirmed. Generally speaking, electrolytic polymers of aromatic compounds are almost insoluble in solvents, so the insulating polymeric film material can be extracted and removed from the film using a solvent. The film after extraction becomes a single film of electrolytic polymer of aromatic compounds, but when the front and back sides of the obtained film were observed with a scanning electron microscope, it was found that the electrolytic polymer was densely deposited on the back side that was in contact with the electrode. However, the other side is porous with many voids. This is because the back side of the composite film before extraction is mostly made up of awakened polymer, whereas the front side is made up of a lot of insulating polymeric film material, and the volume occupied by the electrolytic polymer is small. The structure of this film varies considerably depending on the electropolymerization conditions used, but in any case it gives a porous film that is asymmetric in the thickness direction. Examples of aromatic compounds that give the electrolytic polymer that can be used in the present invention include pyrrole, 6-methylpyrrole, N-methylpyrrole, thiophene, furan, phenol, thiophenol, selenophene, tellurophene, biphenyl, azulene, p-terphenyl, 0-terphenyl, p-quarterphenyl, 2-hydroxybiphenyl, diphenyl sulfide, 2 -(α-chenyl)thiophene, 2-(α
-chenyl)furan, 2-(2-hyloryl)virol,
2-(2-pyrrolyl)thiophene, 2-phenylthiophene, α-chenylphenyl ether, β-furyl-α
-Aromatic compounds such as chenylselenide, 2-(2-pyrrolyl)selenophene, 2-(2-selenienyl)tellophene, N-vinylcarbazole, N-ethynylcarbazole, methylazulene, and pyrene can be used. Also,
Although not aromatic compounds, various substituted butadiene compounds can also be used.Next, various compounds such as organic quaternary ammonium salts, inorganic salts, protonic acids, and esters can be used as electrolytes during electrolytic polymerization. As a solvent, an acetonyl-based solvent is usually used, but any solvent can be selected as long as it is capable of electrolytically polymerizing aromatic compounds and dissolves a suitable electrolyte.

Further, as the insulating polymer film material to be applied on the electrode, any material can be used as long as it can form a uniform film and can be extracted and removed with a solvent after composite formation. Such film materials include polyvinyl chloride resin, polystyrene resin, acrylate polymer material, methacrylate polymer material, etc. However, since these materials are extracted and removed, the porous film of the present invention It is not fundamentally important as a method of manufacturing the material.

On the other hand, as a substrate for electrolytic polymerization, noble metals such as gold, platinum, and palladium, or conductive metal oxides such as tin oxide and indium oxide, or these may be plated, vapor-deposited, or sputtered onto a suitable substrate. It is possible to use those deposited in the following manner, and it is also possible to manufacture them continuously by forming them into a drum shape.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The present invention is not limited to these examples. Example 1 After 100X of chromium and 700X of gold were deposited on a glass substrate, 700X of indium oxide was formed by sputtering. Polyvinyl chloride (molecular weight 7
A film with a thickness of 202 μm was formed from a methyl ether ketone solution of 10,000 ml by a casting method. This film-coated substrate was coated with acetonitrile-methyl ether ketone (1
: A platinum-plated titanium mesh was immersed as a counter electrode in an electrolytic solution prepared by dissolving 0.6 mol/l of tetraethelammonium paratoluenesulfonate and 1 mol/l of pyrrole in the mixed solvent of 1). When pyrrole was electrolytically polymerized at voltage for 10 minutes, black polypyrrole was observed to be deposited. The film was peeled off from the substrate, its weight was measured, and then immersed in a tetrahydrofuran solution for 1 hour to remove the polyvinyl chloride. When the weight of the obtained film was measured, it was 21 inches before dipping, and the film thickness was 45 μm.
The porosity was determined to be 25% by density measurement. The electrical conductivity of this film was 12S/α, indicating high electrical conductivity.

Furthermore, when the structure of the film was measured using a scanning electron microscope, it was found that the back side, which was in contact with the substrate surface, had a dense structure, whereas the front surface had fine irregularities of around 1 μm, indicating that it was porous. Confirmation was omitted.

Example 2 Polyvinyl chloride was deposited on the same substrate as in Example 1.
It was applied to a thickness of μm. This film-coated substrate was immersed in an electrolytic solution in which 1 mol of pyrrole and 0.3 mol of tetraethelammonium verchlorate were dissolved in acetonitrile solvent, and a platinum-coated titanium mensch was used as a counter electrode at a voltage of XOV for 10 Electrolytic polymerization of pyrrole was carried out for minutes.

This film was peeled off from the substrate, the weight of the film was measured, and then immersed in a tetrahydrofuran solution for 1 hour to remove polyvinyl chloride.

When the weight of the obtained film was measured, it was found that 1
At 7%, the film thickness was 5.8 μm. The porosity was determined by measuring the density and was found to be 37%. The electrical conductivity of this film was measured using the four-terminal method and was 2.58/c.
It showed high conductivity of m.

Furthermore, when the structure of the film was observed using a scanning electron microscope, the back surface that was in contact with the substrate surface was fine.

In contrast to the mesh-like structure, the surface had a structure with many gaps, making it an asymmetric porous film.

Example 3 Thickness: 12 μm by casting method on the same substrate as Example 1
Apply a polystyrene film.

On the other hand, Thionoev 1 mol/1. An acetonitrile-nitrobenzene (3:1) solution containing 0.4 mol/l of tetrabuterammonium perchlorate was prepared. The film-coated substrate was immersed in this solution, and thiophene was electrolytically polymerized at a voltage of 4° for 15 minutes between the platinum mesh and the counter electrode. As a result, formation of green-blue polythiophene was observed. After the film was peeled off from the substrate, it was immersed in methyl ethyl ketone for 2 hours to dissolve and remove the bolysterene. The weight of the film thus obtained was 23 cm compared to before dipping, and the film thickness was 5.6 μm. Further, the porosity from density measurement was 28%. Furthermore, when we observed the structure of the film using a scanning electron microscope, we found that
The back side, which was in contact with the substrate surface, was dense and had no clear structure, whereas the front side had a structure with many gaps, confirming that the film had an asymmetric porous structure.

〔Effect of the invention〕

As explained above, according to the method of the present invention, an electrolytic polymer of an aromatic compound is electrochemically composited into a polymer film, and the polymer film material is extracted and removed from the resulting composite film. An asymmetric porous film is obtained. This film has the characteristic that porous films with various structures can be obtained depending on the combination of conditions and exhibit high electrical conductivity.

These films have industrial applications as separation membranes and porous materials for batteries.

Claims (1)

[Scope of Claims] 1. A porous electrolytic polymer film of an aromatic compound, which is porous. 2. A step of closely adhering a polymer film onto the electrode, a step of electrolytically polymerizing an aromatic compound on the electrode with the film to composite the polymer of the aromatic compound into the polymer film, and the composite film. A method for producing a porous electrolytic polymer film, comprising the steps of extracting and removing the polymer film.