JPH047521B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to an improved conductive polymer film and a method for producing the same. [Prior Art] A conductive polymer film can be formed on an electrode substrate by dissolving certain aromatic compounds in a solvent containing an electrolyte and performing electrolytic oxidation. Known examples of such aromatic compounds include heterocyclic compounds such as virols and thiophenes, and polycyclic aromatic compounds such as azulene, birene, and triphenylene [for example, J. Burgon (J.
Bargon), S. Mohmand, RJ Waltman, IBM Journal
of Research & Development (IBM Journal of Research & Development) No.
27, No. 4, p. 330 (1983)]. However, conventional conductive polymer films formed by direct electrolytic oxidation on electrode substrates have the following drawbacks. (1) Because the film has low mechanical strength, it is easy to tear and difficult to handle, both on a substrate and when isolated as a film. (2) It was difficult to control electrical conductivity. (3) It has weak adhesion to the substrate and is likely to peel off during film formation or during the cleaning process after formation. (4) If an electrode substrate such as Nesa Glass is used that has an electrical resistance equal to or lower than that of the electrolytic solution or the aromatic polymer film that is formed, it will not be possible to form a uniform film and there will be large variations in film thickness. It was seen. [Object of the Invention] The present invention was made to eliminate these drawbacks, and its purpose is to provide a conductive polymer film with excellent electrical conductivity, mechanical strength, and adhesion, and a method for producing the same. There is a particular thing. [Structure of the Invention] To summarize the present invention, the first invention of the present invention is an invention of a conductive polymer film, which includes a thermoplastic resin film formed on an electrode substrate, and a thermoplastic resin film formed on the substrate by electrolytic oxidation. It is characterized by being made of an electrochemically formed aromatic polymer material. The second invention of the present invention is an invention of a method for manufacturing a conductive polymer film, which includes a step of manufacturing a thermoplastic resin film on an electrode substrate, and applying an aromatic polymer material thereon by electrolytic oxidation. It is characterized in that it includes each step of electrochemically forming. Conductive polymer films produced by electrolytic polymerization are usually produced by placing an electrolytic substrate together with a counter electrode in a solution containing an aromatic compound that will become a monomer for electrolytic polymerization and an electrolyte for conducting electricity in an organic solvent such as acetonitrile. , is formed by passing current between both electrodes. At this time, if the electrode substrate is coated with an insulating polymer film, it will naturally not be possible to conduct electricity and no conductive film will be formed. However, the present inventors coated various thermoplastic resin films on the electrode substrate and combined them with an appropriate electrolytic reaction solution that does not dissolve the film, so that the electrolytic reaction proceeded in the same way as on a normal electrode substrate. I found out what to do. The film thus obtained is a mixture of a thermoplastic resin film and an aromatic polymer film produced by electrolytic oxidation, and the state of the mixture depends on the production conditions, and the characteristics of the film as a whole will appear. Therefore, if a material with high film strength is selected as the thermoplastic resin film, a conductive polymer film with high film strength can be produced. Further, depending on the manufacturing conditions, there are cases where an integrated mixed film is formed, and cases where two layers can be formed without being mixed at all. The electrical conductivity of any of these films can be controlled arbitrarily by changing the polymerization time, and the electrical conductivity can be changed by about 10 orders of magnitude. Further, even when a Nesa glass substrate is used, polymerization proceeds completely uniformly, and the film thickness distribution is extremely small. This is presumed to be because when a highly conductive film such as polypyrrole is made directly on a Nesa glass substrate, polymers are formed from the side closer to where the lead wires are taken, and because of this high electrical conductivity, polymerization progresses in a concentrated manner. Ru. On the other hand, in the film of the present invention, the electrical conductivity is low at the initial stage of polymerization and gradually increases, so that a uniform film can be formed. Further, by using a thermoplastic resin film that has good adhesion to the substrate, the adhesion of the formed conductive polymer film can be improved. The reason why a uniform and high-quality conductive polymer film is obtained in this way is that the thermoplastic polymer film swells to some extent in the electrolytic solution, allowing monomer molecules to diffuse into the crosslinked film, and electrolytic oxidation reactions occur on the electrode surface. It is presumed that this is due to progress. Therefore, by selecting a composition of the electrolytic reaction solution that allows the monomer to diffuse into the thermoplastic resin film, a uniform conductive polymer film can be obtained. Therefore, the polymer film may be any thermoplastic resin and is not limited in type. The electrolyte only needs to satisfy the following conditions. (1) Not to dissolve the thermoplastic resin film (2) To be able to dissolve the electrolytic salt and the monomer for electrolytic polymerization (3) To be able to diffuse the monomer for electrolytic polymerization into the thermoplastic resin film Commonly used additives such as plasticizers, pigments, and dyes may be added to the polymeric material for films, and even if they are added, they will not dissolve into the electrolyte. The desired properties of the resulting conductive polymer film remain unchanged. [Examples] Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. In addition, Figure 1 shows the polymerization time (horizontal axis) (minutes) of polypyrrole and the electrical conductivity (vertical axis) of the mixed film.
(σ). Example 1 Chloromethylated polystyrene (hereinafter abbreviated as CMS) was deposited on a Nesa glass substrate by spin coating.
(molecular weight 300,000) was applied to a thickness of 1 μm. The substrate coated with this film was immersed in an electrolytic solution using a platinum mesh electrode as a positive electrode and a negative electrode.
The electrolytic polymerization of virol was carried out at a constant voltage of 1.5V.
The electrolytic solution used was acetonitrile-water-ethylene glycol (90:5:5) in which 1M of virol was dissolved and 0.3M of tetraethylammonium tetrafluoroborate was dissolved as an electrolytic salt. When the electrolysis time was varied from 5 to 60 minutes, black polypyrrole was precipitated on the substrate and the film thickness increased even though the Nesaglass substrate was covered with an insulating film. . FIG. 1 is a graph showing the relationship between polymerization time and electrical conductivity of the obtained film. It has been revealed that by changing the polymerization time, the electrical conductivity of the film can be changed by about nine orders of magnitude, and that a film with a desired electrical conductivity can be produced. Example 2 Polyvinyl chloride (molecular weight 70
10,000) Apply a film to a thickness of approximately 1 μm using the spin coating method. This substrate was mixed with 1M virol in acetonitrile-water-ethylene glycol (98:1:1) solvent.
It was immersed in a solution containing 0.3M of tetraethylammonium tetrafluoroborate, and electrolytically polymerized at 1.3V for 20 minutes. As in Example 1, a black polypyrrole film was deposited. This polypyrrole was formed to be laminated between a Nesa glass substrate and polyvinyl chloride. This film could be easily peeled off from the Nesa glass substrate, and a film with a smooth surface and extremely high mechanical strength was obtained, and could be stretched approximately 1.5 times. The electrical conductivity was approximately 80/Ω·cm on the polypyrrole surface. Example 3 As in Example 2, polyvinyl chloride was spin-coated onto a Nesa glass substrate to a thickness of 1 μm.
This was electrolytically oxidized at 1.2 V for 20 minutes in a solution containing 3 M of virol and 0.3 M of tetraethylammonium tetrafluoroborate in a mixed solvent of acetonitrile-methyl ethyl ketone-water-ethylene glycol (58:40:1:1). . Example 2
Polypyrrole was precipitated in the same manner as in Example 2.
Unlike in Example 1, the obtained film did not have a laminated structure but a single layer structure, and its electrical conductivity was 3.5/Ω·cm, which was about the same as in Example 1. Comparative Example 1 Even when the same films as in Examples 2 and 3 were subjected to electrolytic polymerization in acetonitrile-water (9:1), no polypyrrole was deposited. As is clear from Examples 2 and 3 and Comparative Example 1, it is necessary to optimize the electrolytic polymerization solvent for each resin in order to produce a uniform film. That is, it is necessary that the monomer can sufficiently diffuse through the thermoplastic resin film and reach the electrode surface. It is presumed that in Comparative Example 1, diffusion could not be achieved. In the case of each of the above examples, if there is sufficient space in the thermoplastic resin film, the electrolytically oxidized polypyrrole will grow within the film, and a composite film as in Examples 1 and 3 will be obtained. If it cannot penetrate, it is estimated that the film will have a two-layer structure. Examples 4 to 44 The thermoplastic resin films shown in Table 1 below were each applied to a thickness of about 1 μm on a Nesa glass substrate using a spin coating method or a casting method. This substrate was dissolved in 1M pyrrole and 0.3M tetraethylammonium tetrafluoroborate in the solvent shown in Table 1, and electrolytically polymerized at 1.2V for 20 minutes. In both systems, black polypyrrole was precipitated, and a uniform film similar to that of Example 1 was obtained. Table 1 shows the measured values of the film thickness and electrical conductivity of the obtained composite film. In Table 1, the substrates are Nesa glass substrate,
Polymerization time was 20 minutes/room temperature. Also, MEK is methyl ethyl ketone, EG is ethylene glycol,
DMF means N,N-dimethylformamide.

【table】

[Table] As is clear from Table 1 above, it was found that all systems exhibited high electrical conductivity. In this way, most thermoplastic resin films that can be applied as a thin film onto a substrate can be converted into conductive polymer films by appropriately selecting the composition of the electrolytic polymerization solution. Therefore, the thermoplastic resin film that can be used in the present invention is not limited to the above embodiments, and a wide range of materials can be used. Examples 45 to 50 As in Example 1, CMS was spin-coated onto a Nesa glass substrate to a thickness of about 1 μm. This substrate was used as a positive electrode, and 3-methylpyrrole (Example 45), N-methylpyrrole (Example 46), thiophene (Example
47), azulene (Example 48), methyl azulene (Example 49), and pyrene (Example 50) were dissolved in each solvent shown in Table 2 below, and electrolytic polymerization was performed using a platinum electrode as a counter electrode in the solution. Ivy. After 20 minutes of electrolytic polymerization, both film thickness increased and the electrical conductivity of the films improved. The results are summarized in Table 2. In Table 2, the substrates are Nesa glass substrate,
The CMS film thickness was approximately 1 μm, and the polymerization time was 20 minutes/room temperature.
Moreover, 0.3M tetraethylammonium tetrafluoroborate was used as the electrolyte in Examples 45 to 48.

[Table] Examples 51, 52 The same CMS as in Example 1 was applied to a glass substrate (Example 51) on which gold was deposited approximately 0.1 μm thick, and an n-type silicon substrate (Lin dove, resistance 15 Ω cm, Example 52). 1μ
Spin coating was performed to a thickness of m. This substrate was immersed together with a counter electrode in a solution containing 3M of pyrrole and 0.3M of tetraethylammonium toluenesulfonate in acetonitrile, and electrolytic polymerization was performed at 1.2V for 20 minutes. As a result, on gold-deposited substrates,
A film with a thickness of 1.8 μm and an n-type silicon substrate of 1.35 μm was obtained, and the electrical conductivity was 4.5/1, respectively.
It was Ω・cm, 1.2/Ω・cm. In this way, uniform conductive polymer films were obtained on both metal and semiconductor substrates. Although the examples have been given above, the present invention is a method for producing a conductive polymer film based on a new principle that has never existed before, and is not limited to the above examples, but a wide range of combinations of materials are possible. . [Effects of the Invention] As explained above, according to the present invention, an aromatic compound such as pyrrole that forms a conductive polymer material by electrolytic oxidation reaction is electrolyzed on an electrode substrate coated with a thermoplastic resin film. When oxidized, a composite film of a thermoplastic resin film and a conductive aromatic polymer material can be obtained with good uniformity. These films exhibit high electrical conductivity and also
It has the advantage that electrical conductivity can be controlled arbitrarily by changing the polymerization time. Furthermore, by using a thermoplastic resin film with high mechanical strength, a conductive polymer film with excellent mechanical strength can be obtained, and by using a thermoplastic resin film with strong substrate adhesion, it is possible to obtain a conductive polymer film with high mechanical strength. Particularly remarkable effects, such as the ability to obtain a conductive polymer film, can be achieved.

[Brief explanation of drawings]

FIG. 1 is a graph showing the relationship between the polymerization time of polypyrrole and the electrical conductivity of a mixed film when using a Nesa glass substrate coated with chloromethylated polystyrene.

Claims (1)

[Claims] 1. A conductive polymer comprising a thermoplastic resin film formed on an electrode substrate and an aromatic polymer material electrochemically formed on the substrate by electrolytic oxidation. film. 2. A conductive polymer comprising the steps of producing a thermoplastic resin film on an electrode substrate and electrochemically forming an aromatic polymer material thereon by electrolytic oxidation. film. manufacturing method