JPS6148542B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a polymer semiconductor obtained by treating an acetylene polymer having a fibrous microcrystalline (fibril) structure with a specific electron-accepting compound.

The powdered acetylene polymer obtained by polymerizing acetylene with a Ziegler-Natsuta catalyst is a P-type semiconductor with an electrical conductivity of approximately 10 ^-9 Ω ^-1 cm ^-1 .
Its usefulness as a variety of electrical elements is known. Furthermore, it is already known that when this powdered acetylene polymer is treated with an electron-accepting compound, its electrical conductivity increases by up to three orders of magnitude [DJ
Berets et.al, Trans.Faraday.Soc., 64 , 823
(1968)]. However, the powdery acetylene polymer used here is an aggregate of non-fibrous microcrystals, and the molecular chain morphology is essentially different from the fibrous microcrystalline acetylene polymer used in the present invention. Therefore, the resulting molded products are all brittle and do not have sufficient mechanical strength, and the range of electrical conductivity is narrow, approximately 10 ^-9 to 10 ^-6 Ω ^-1 cm ^-1 , so they are not suitable for electrical conductivity. When used as a component, it has the disadvantage that its scope of use is inevitably limited.

In view of the above circumstances, the present inventors have arrived at the present invention as a result of various studies on polymer semiconductors having high mechanical strength and a wide range of electrical conductivity.

That is, the present invention is made by treating an acetylene polymer having a fibrous microcrystalline structure with at least one electron-accepting compound selected from the group consisting of aluminum tribromide, boron tribromide, and boron trichloride. Regarding polymer semiconductors.

Since the polymer semiconductor of the present invention has a fibrous microcrystalline structure, it not only has high mechanical strength, but also has electrical conductivity that can be adjusted by adjusting the type and amount of the electron-accepting compound. 10 ^-9 to 1Ω
It is extremely useful industrially because it can be controlled over a wide range up to ^-1 cm ^-1 .

The acetylene polymer having a fibrous microcrystalline structure used in the present invention may be any acetylene polymer produced by any method as long as it has a fibrous microcrystalline structure. As a specific manufacturing example, the following method can be mentioned, for example. Note that the acetylene polymer having a fibrous microcrystalline structure referred to here is a crystalline polymer in which fibrous microcrystals with a diameter of 200 to 30 Å are assembled in a disordered manner, and has cis or trans conjugated double bonds. It is a linear acetylene polymer consisting of .

(1) A catalyst solution prepared by dissolving a catalyst system consisting of a transition metal compound and an organometallic compound in an aromatic hydrocarbon such as toluene or an aliphatic hydrocarbon such as hexadecane and an acetylene gas at the interface near the free surface or on a solid surface. A method for producing membranous and fibrous acetylene polymers by polymerizing on the surface coated with this catalyst solution (Japanese Patent Publication No. 1973-
32581) (2) Using hexane as a solvent, μ-(η ¹ :η ⁵ -
cyclopentadienyl)―tris(η―
cyclopentadienyl) dititanium (Ti-Ti)
A method for producing a gel-like acetylene polymer by polymerizing acetylene with a special transition metal compound [C ₅ H ₄ ) ₅ (C ₅ H ₅ ) ₃ Ti ₂ ] [S.L.Hsu et.al.
J Chem Phys, 69 (1), 106-111
(1978)] (3) Using an aromatic compound as a polymerization solvent and a catalyst system mainly composed of a transition metal compound and an organometallic compound, the transition metal compound is added at a concentration of 0.0001 to 0.1 molar relative to 1 part of the aromatic compound. A method for producing a gel-like acetylene polymer by polymerizing acetylene under stirring.

The acetylene polymer gel obtained by the methods (2) and (3) above is used after being molded into any shape by a normal molding method such as pressure molding.

The electron-accepting compounds used in the present invention are aluminum tribromide, boron tribromide, and boron trichloride, and two or more of these may be used as a mixture.

Examples of methods for treating an acetylene polymer having a fibrous microcrystalline structure with the electron-accepting compound include (1) directly immersing the acetylene polymer in an electron-accepting compound; (2) electron-accepting A method in which the acetylene polymer is treated with an electron-accepting compound by placing the compound in an organic or organic solvent that does not react with the compound, immersing the acetylene polymer in this solution, and diffusing the acetylene polymer in the solvent. (Differences in electrical conductivity may be observed depending on the solvent used) (3) Place the acetylene polymer in vacuum or in an inert gas, and treat the acetylene polymer with vapor of an electron-accepting compound. (4) A method in which an electron-accepting compound is heated above its melting point in vacuum or in an inert gas, and the acetylene polymer is immersed in the melt.

Although the preferred treatment temperature cannot be determined unconditionally since it varies depending on the treatment method and the type of electron-accepting compound, it is generally within the range of 0°C to 300°C.

Treatment with these electron-accepting compounds increases the weight of the acetylene polymer by up to 100%. The electrical conductivity of the acetylene polymer after treatment increases with increasing weight, and the electrical conductivity reaches a maximum of 1 Ω ^-1 cm ^-1
reach up to.

The acetylene polymer treated in this way is a P-type semiconductor, and can not only be used as a polymer semiconductor useful as a flexible electric/electronic device as it is, but also can be used as an n-type semiconductor. A Pn heterojunction element can also be easily made by combining them. In addition, the band gap energy of acetylene high polymer is approximately 1.6ev,
It is also useful as various optical/electrical conversion elements.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1 5.1 ml (15.0 mmol) of titanium tetrabutoxide was added to a glass reaction vessel with an internal volume of 500 ml under a nitrogen atmosphere, and dissolved in 20.0 ml of toluene.
A catalyst solution was prepared by adding 5.4 ml (40 mmol) of triethylaluminum with stirring and reacting.

The reaction vessel was cooled with liquid nitrogen, the nitrogen gas in the system was evacuated using a vacuum pump, and then the reaction vessel was cooled to -78°C.

After the reaction vessel was rotated to uniformly adhere the catalyst solution to the inner wall of the reaction vessel, purified acetylene gas at a pressure of 1 atmosphere was immediately introduced while the reaction vessel was left standing to initiate polymerization. Simultaneously with the initiation of polymerization, an acetylene high polymer with metallic luster was deposited on the inner wall of the reaction vessel. After the polymerization reaction was carried out for 1 hour at a temperature of -78° C. while maintaining the acetylene pressure at 1 atm, unreacted acetylene was evacuated with a vacuum pump to stop the polymerization. After removing the remaining catalyst solution with a syringe under a nitrogen atmosphere, washing was repeated six times with 100 ml of purified toluene while keeping the temperature at -78°C, and then vacuum drying was performed at room temperature.

The part where the catalyst solution adhered to the inner wall of the reactor has an area equal to that part, a thickness of 90 μm, and a cis content of 98
% membranous acetylene polymer was obtained.

The electrical conductivity (DC four-probe method) of this film-like acetylene polymer was 2.5×10 ^-8 Ω ^-1 cm ^-1 at 20°C.

Furthermore, when the film-like acetylene polymer was observed using a scanning electron microscope, it was found that the film-like acetylene polymer was an aggregate of fibrils with a diameter of 200 to 300 Å.

50 ml of toluene and 5.0 gr of aluminum tribromide were charged into a 100 ml reactor under a nitrogen gas atmosphere. The solution was a pale yellow homogeneous solution. The film-like acetylene polymer was immersed in this solution and left to stand at room temperature for 5 hours.

After the treatment, the film-like acetylene high polymer was washed three times with 100 ml of toluene, and then vacuum-dried to obtain a dark brown acetylene high polymer.

After the treatment, the acetylene polymer had a weight increase of 9.7% and was a P-type semiconductor with an electrical conductivity of 4.13×10 ⁻¹ 1Ω ⁻¹ ·cm ⁻¹ .

Example 2 The film-like acetylene polymer obtained in Example 1 was placed in a glass reactor, and after removing air from the system with a vacuum pump, boron trichloride (commercially available product vacuum distilled) was added to - The reactor was cooled to 30° C., and the vapor at the vapor pressure of boron trichloride at that temperature was introduced into the reactor for treatment for 2 hours.

After the treatment, unreacted boron trichloride was exhausted from the system using a vacuum pump. After treatment, the acetylene polymer has a weight increase of 56% and an electrical conductivity of 8.5×10 ^-11 Ω.
It was a P-type semiconductor with ^-1 cm ^-1 .

Example 3 A membranous acetylene polymer was treated in exactly the same manner as in Example 2, except that boron tribromide was used in place of the boron trichloride used as the electron-accepting compound in Example 2. After treatment, the acetylene polymer increased in weight by 23% and had an electrical conductivity of 1.2×10 ^-1 Ω ^-1 .
cm ^-1 P-type semiconductor.

Example 4 200 ml of toluene purified in a conventional manner as a polymerization solvent, 2.94 mmol of tetrabutoxytitanium and 7.34 mmol of triethylaluminum as catalysts were sequentially charged at room temperature into a glass reactor 1 that was completely purged with nitrogen gas. A catalyst solution was prepared. The catalyst solution was a homogeneous solution. The reactor was cooled with liquid nitrogen, and the nitrogen gas in the system was exhausted using a vacuum pump.

The reactor was cooled to -78°C, and while stirring the catalyst solution with a magnetic stirrer, purified acetylene gas was blown in at a pressure of 1 atm. At the beginning of the polymerization reaction, the entire system became agar-like and stirring became difficult. Summer.

The polymerization reaction was continued for 24 hours while maintaining the acetylene gas at 1 atm. The system was agar-like with a reddish-purple color. After the polymerization was completed, unreacted acetylene gas was removed, and the system was repeatedly washed four times with 200 ml of purified toluene while maintaining the temperature at -78°C. Even after washing, the solution remained slightly brownish and the catalyst was not completely removed. The gel-like acetylene polymer swollen in toluene was in the form of uniform chips with intertwined fibrous microcrystals, and no powder or lump-like polymer was produced.

When a part of the homogeneous gel was taken out and dried and the amount of acetylene high polymer in the gel was measured, the amount of acetylene high polymer in the gel was 10% by weight.
It was contained. The resulting acetylene polymer had a cis content of 98%.

The above gel-like material is 10mm thick, 100mm long, and 50mm wide.
It was placed in a mold, sandwiched between chrome-plated ferro plates, and press-molded at room temperature under a pressure of 100 kg/cm ² while removing toluene to obtain a flexible and strong film-like molded product with a film thickness of 5 mm. Ta.

This film-shaped molded product has an electrical conductivity (measured using the DC four-probe method) of 5×10 ^-8 Ω ^-1 cm ^-1 at 20°C.
It was a type semiconductor.

The obtained molded article was treated with aluminum tribromide in the same manner as in Example 1.

The acetylene polymer molded product after the treatment was a P-type semiconductor with an electrical conductivity of 1.02Ω ⁻¹ ·cm ⁻¹ .

Example 5 The film-shaped molded acetylene polymer obtained in Example 4 was treated with boron trichloride in the same manner as in Example 2.

After the treatment, the acetylene polymer had a weight increase of 62% and was a P-type semiconductor with an electrical conductivity of 1.32 Ω ^-1 ·cm ^-1 .

Example 6 The film-shaped molded acetylene polymer obtained in Example 4 was treated with boron tribromide in the same manner as in Example 3.

After the treatment, the acetylene polymer had a weight increase of 27% and was a P-type semiconductor with an electrical conductivity of 2.7×10 ⁻¹ Ω ⁻¹ ·cm ⁻¹ .

Claims (1)

[Claims] 1. A polymer obtained by treating an acetylene polymer having a fibrous microcrystalline (fibril) structure with at least one electron-accepting compound selected from the group consisting of aluminum tribromide, boron tribromide, and boron trichloride. semiconductor.