JPS61118454A - Electrically conductive polymer material having electrical anisotropy, and production thereof - Google Patents

Abstract

PURPOSE:To provide a material composed of a highly oriented polyacetylene containing a dopant, exhibiting high electrical conductivity, useful as an electrical or electronic element having anisotropic electrical conductivity and capable of giving a p/n junction element. CONSTITUTION:A highly oriented polyacetylene prepared by polymerizing acetylene using a liquid crystal substance as a polymerization medium, is treated with an electron accepting substance or an electron donative substance. The liquid crystal substance is preferably nematic liquid crystal.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a conductive polymer material having electrical anisotropy obtained from highly oriented polyacetylene and a method for producing the same.

[Background of the invention]

In the method of polymerizing acetylene using a Ziegler-Natsume catalyst consisting of a transition metal compound and an organometallic compound, when the polymerization reaction is carried out at the interface near the free surface of acetylene and a polymerization catalyst solution, film-like polyacetylene is directly produced. (Special Publication No. 48-32581)
.

This film has a structure in which fibrils (fibrous microcrystals) with a diameter of several hundred micrometers are assembled in a disordered manner.

This polyacetylene is known as an organic semiconductor, and can be made into a material with high electrical conductivity by doping it with an electron-donating substance or an electron-accepting substance (Japanese Patent Laid-Open No. 129426/1983). Generally, in polymeric materials, it is known that the material properties are improved when the two-dimensionality is reflected in the macroscopic structure of the material, that is, when the material has a -axis orientation. The above polyacetylene does not melt even when heated, and no solvent has been found that dissolves this polymer. For this reason, the following five methods have been proposed as methods for obtaining highly oriented polyacetele/.

(1) The above polyacetylene is stretched by mechanical operation under heating (8ynth@tic M@talg,
Volume 1 fJc pages 175-184 (1979/198G)
:1(2) Synthesize polyacetylene under siearch 0- (MoL 0ryst, Liq, 0rys
t, Vol. 77, pp. 137-146 (1981)) (3) Epitaxial formation on organic crystals such as biphenyl (T, Polym, 8ai,:
Polym, II6tt-ma. Volume 20, No. 305~
508 (1982)) The materials obtained by these methods exhibit electrical anisotropy, and the electrical resistance in the orientation axis direction is less than half that of the unstretched material. This electrical anisotropy is maintained even after treatment with an electron-donating substance or an electron-accepting substance. However, each of these materials has the following drawbacks and is not practical. Method (1) This method involves the cutting of fibrils and has disadvantages such as the inability to maintain the initial sample shape.The polyacetylene film obtained by method (2) has an extremely small thickness and is difficult to handle.

With method (3), only a small area of the sample can be obtained.

The present inventors previously discovered a method of polymerizing acetylene in a liquid crystal medium as a method for obtaining a highly oriented polyacetylene film by a method other than the above (Japanese Patent Application No. 129408/1982).
. The shape of the membrane obtained by this method can be freely selected. Furthermore, the film thickness can be made significantly thicker than in (2) above. Furthermore, the area depends on the size of the reactor used during synthesis, and it can be said that there is no substantial limitation on the area. For these reasons, highly oriented polyacetylene synthesized in a liquid crystal medium can be said to be a material suitable for practical use.

However, there is still room for improvement.

[Purpose of the invention]

An object of the present invention is to provide a conductive polymer material having electrical anisotropy, which is obtained by further modifying highly oriented polyacetylene synthesized using a liquid crystal substance, and a method for producing the same.

[Summary of the invention]

To summarize the present invention, the first aspect of the present invention relates to a conductive polymer material having electrical anisotropy, and is characterized in that it includes highly oriented polyacetylene containing a dopant.

Further, the second invention of the present invention relates to a method for producing the above-mentioned polymeric material, in which highly oriented polyacetylene obtained by polymerizing acetylene using a liquid crystal substance as a polymerization medium is used as an electron-accepting substance or an electron-donating substance. It is characterized by treatment with sexual substances.

The present invention will be specifically explained below.

Examples of electron-donating substances that can be used in the present invention include alkali metals such as lithium, sodium, potassium, rubidium, and cesium.

On the other hand, examples of electron-accepting substances include nitrogen (e.g. fluorine, chlorine, bromine and iodine), Lewis acids (e.g. phosphorus pentafluoride, arsenic pentafluoride, antimony pentafluoride, boron trifluoride, boron trichloride, boron tribromide, ferric chloride, aluminum chloride, sulfur trichloride, etc.), and protonic acids (eg, hydrofluoric acid, hydrochloric acid, hydrogen bromide, perchloric acid, sulfuric acid, nitric acid, etc.). Hereinafter, these processing agents will be collectively referred to as dopants.

The method for treating polyacetylene with an electron-donating substance or an electron-accepting substance is as follows: (1) When the dopant is a gas, the polymer is exposed to the gas.

(2) If the dopant is a liquid, immerse the polymer in the liquid. (3) If the dopant is a solid, the polymer is immersed in a solution of the dopant in a suitable solvent. (
4) When the dopant is an alkali metal, the alkali metal -
Examples of methods include immersing the polymer in a solution of a naphthalene complex in tetrahydro7rane (THF).

K for obtaining a highly oriented polyacetylene thin film is produced by dissolving a Ziegler-Natsume catalyst in a liquid crystal material, aligning the liquid crystal material, and polymerizing acetylene on its free surface. As a method for aligning a liquid crystal substance, (1) a surface-treated substrate is used; (2) There are two types: (2) using external field application; Method (1) includes polymer coating, rubbing,
Includes oblique deposition and grating surface treatment.

The method (2) includes applying an external field such as an electric field, a magnetic field, and shear stress. Among these methods, method (2) requires that the liquid crystal material be sandwiched between two glass substrates, so that sufficient diffusion of acetylene does not occur. On the other hand, method (1) is the most preferred method because polymerization can be performed using a single glass substrate. However, the application of shearing force in (2) can be performed using a single substrate. In other words, this is a method in which a liquid crystal material containing a polymerization catalyst is applied onto a substrate, and the substrate is tilted at an angle just before polymerization, thereby utilizing the shear core force caused by the flow of the liquid crystal material. Examples of methods for orienting the liquid crystal material include the use of a combination of the above, for example, a substrate rubbed with a polymer coating. A combination of these methods will enhance the alignment of the liquid crystal material.

The liquid crystal material is preferably one that easily dissolves the polymerization catalyst and does not chemically react with the catalyst. That is, when looking at the molecular structure of a liquid crystal substance, it is preferable that it does not have a substituent that is active with respect to a polymerization catalyst. Furthermore, since acetylene, which is a raw material, is a gas, it is desirable to use a liquid crystal material in which acetylene gas can easily diffuse. *A nematic liquid crystal is more preferable.

[Embodiments of the invention]

Hereinafter, the present invention will be explained in more detail with reference to Examples.
The invention is not limited to these examples.

Example 1 4-(trans-
An equimolar mixture of 4-n-"f-propylcyclohexyl)-nitoxybenzene and 4-()lance-4-n-propylcyclohexyl)-butoxybenzene was added. From the nematic liquid crystal phase of this liquid crystal mixture, The transition temperature to the orthotropic liquid phase is 35°C.
51 .mu.l of -butoxytitanium and 61 .mu.l of triethylaluminum were added and stirred for 30 minutes to age the catalyst. The above transition temperature decreased to 27° C. due to the inclusion of the Ziegler-Natsuta catalyst.

In addition to this, a glass substrate (
30 x 6 Q)), and the liquid crystal material containing the above catalyst was dropped onto this substrate under a nitrogen atmosphere. This container was attached to a polymerization apparatus, and nitrogen was evacuated using a vacuum pump. Immediately before polymerization, the container was tilted to give fluidity to the liquid crystal material on the glass substrate, and acetylene gas was instantly blown into the container, resulting in the immediate formation of polyacetylene. After 5 minutes, unreacted acetylene gas was removed, the glass container was removed from the polymerization apparatus, and nitrogen was introduced. The generated polyacetylene film is washed in the order of toluene → hydrochloric acid methanol solution → toluene to remove the liquid crystal substance and catalyst.

Finally, it was vacuum dried to obtain a highly oriented polyacetate/thin film with the same area as the glass substrate.

This -axially oriented polyacetylene was placed in an airtight vacuum container and exposed to iodine vapor for 5 minutes. The electrical conductivity of this sample (DC four-probe method) is 489 in the direction parallel to the fibril orientation axis! -', in the vertical direction 21Elα-! Met.

Example 2 The highly oriented polyacetylene obtained in Example 1 was immersed in a nitromethane solution of iron trichloride (15 mol//) K3G for seconds, then washed with toluene and vacuum dried. The electrical conductivity of this sample is 1268 (F
ll-'', vertically 708 cW1-grave.

Example 3 The nine-axis oriented polyacetylene obtained in Example 1 was immersed in a solution of sodium/s7talene complex in tetrahtomifuran (11 mol//) for 10 minutes, then washed with toluene and dried in vacuum. The electrical conductivity of this sample is 4-2 in the direction parallel to the fibril orientation axis and 1 in the perpendicular direction.
7 e cm-teh ivy.

Example 4 A liquid crystal containing a catalyst was prepared in the same manner as shown in Example 1.

A rubbed polyethylene substrate (3ow x 6om) is placed in a 300mm glass container, and a few drops of a liquid crystal material containing a catalyst is added onto the substrate with a syringe under a nitrogen atmosphere. after that,
Tilt the glass container slightly and spread the liquid crystal evenly over the substrate.

A ``vacuum line'' was attached to this container, and nitrogen in the reaction container was evacuated using a vacuum pump. When acetylene was blown into this container, a polyacetylene film was formed on the polyethylene substrate. After 5 minutes, unreacted acetylene gas was removed, the glass container was removed from the polymerization apparatus, and nitrogen was introduced. Washing was carried out in the order of toluene → methanol solution of hydrochloric acid → toluene to remove the liquid crystal substance and catalyst, and finally vacuum drying to obtain a highly oriented polyacetylene film.

This -axis oriented sample was placed in a glass container, and after removing air, iodine vapor was introduced and treated for 5 minutes. The electrical conductivity of this sample is 978 in the direction parallel to the fibril orientation axis.
It was 558 CIII-'' in the 51-% vertical direction.

(Effects of the Invention) As explained above, according to the present invention, by treating highly oriented polyacetylene synthesized in a liquid crystal medium with an electron donating substance or an electron accepting substance, it not only has high conductivity but also , it is possible to provide a material having that anisotropy.

Materials with such anisotropy can not only be used as conductive polymer materials useful in electrical and electronic devices, but also
Since a p/n junction element can also be made, it is also useful as an optical sensor and a solar cell.

Claims (1)

[Scope of Claims] 1. A conductive polymer material having electrical anisotropy, characterized by including highly oriented polyacetylene containing a dopant. 2. A conductive polymer having electrical anisotropy, characterized in that highly oriented polyacetylene obtained by polymerizing acetylene using a liquid crystal substance as a polymerization medium is treated with an electron-accepting substance or an electron-donating substance. Method of manufacturing the material.