JPH048445B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a method for producing poly 2,5-thienylene vinylene. This polymer is useful as a highly conductive material. <Prior art> Poly 2,5-thienylene vinylene is known as a linear conjugated polymer, and its production method involves the reaction of a diphosphonium salt with a dialdehyde.
It is known that it can be synthesized by the Wittig reaction method etc. (Macromolecular Chemie Vol. 131, p. 15 (1970)).Also, it is known that the polymer sulfonium salt obtained by polymerizing a disulfonium salt with a base is heat-treated. A method for obtaining poly-2,5-thienylene vinylene is also known (Japanese Unexamined Patent Publication No. 61-148231). is produced in powder form, and the polymers except for low polymers are insoluble and infusible, so it is virtually impossible to form it into a film or fiber form as it is, so a special powder forming method is used to form it. Furthermore, the electrical conductivity of a composition doped with film-like poly-2,5-thienylene vinylene obtained from the latter precursor having a sulfonium salt in its side chain was 15S at the highest. /cm, and cannot be said to have sufficiently high conductivity as a conductive material.The present inventors have developed poly-2,5-
As a result of intensive studies on methods for obtaining thienylene vinylene, we found that a precursor having an alkoxy group in the chain not only gives poly-2,5-thienylene vinylene by eliminating the alkoxy group, but also forms poly-2,5-thienylene vinylene by doping. It has been found that it can be converted to poly-2,5-thienylene vinylene, which provides higher conductivity than 2,5-thienylene vinylene. The object of the present invention is to provide poly-2,5 which provides high conductivity.
- To provide a method for producing thienylene vinylene. <Means for solving the problems> That is, the present invention substantially solves the general formula (1) _R1 : Provides a method for producing poly-2,5-thienylenevinylene, which comprises subjecting a polymer precursor to an elimination treatment to an alkoxy group consisting of a repeating unit represented by an alkyl group having 1 to 10 carbon atoms. . The present invention will be explained in detail below. In the present invention, as a precursor of poly-2,5-thienylene vinylene, substantially the general formula (1) is used. A polymer precursor having an alkoxy group in the side chain consisting of a repeating unit represented by is used. In the general formula (1), R ₁ is an alkyl group having 1 to 10 carbon atoms,
For example, methyl, ethyl, propyl, isopropyl, n-butyl, 2-ethylhexyl, cyclohexyl, etc., and have 1 to 6 carbon atoms.
Alkyl groups, particularly methyl and ethyl groups, are preferred. The method for synthesizing the polymer precursor used in the present invention is not particularly limited, but the method using the sulfonium salt decomposition method described below is preferable for the synthesis of the polymer precursor that provides higher conductivity.
This is particularly preferred since 2,5-thienylenevinylene is obtained. The monomer used in the sulfonium salt decomposition method has the general formula (2) R ₂ , R ₃ : Hydrocarbon group having 1 to 10 carbon atoms A ^- : 2,5-thienylenedimethylbissulfonium salt represented by a counter ion, R ₂ and R ₃ are carbonized groups having 1 to 10 carbon atoms Hydrogen groups such as methyl, ethyl, propyl, isopropyl, n-butyl, 2-ethylhexyl,
Examples include phenyl, cyclohexyl, benzyl groups, etc., and hydrocarbon groups having 1 to 6 carbon atoms, particularly methyl and ethyl groups, are preferred. Any counter ion A ⁻ of the sulfonium salt can be used. For example, halogen, hydroxyl, boron tetrafluoride, perchloric acid, carboxylic acid, sulfonate ions, etc. can be used, and among them, halogen and hydroxyl ions such as chlorine, bromine, and iodine are preferred. The solvent for condensation polymerization is water, alcohol alone,
A mixed solvent containing water and/or alcohol can also be used, but a solvent containing water is preferred in order to increase the solubility of the alkali. The alkaline solution used for condensation polymerization is preferably a strongly basic solution with a pH of 11 or higher, and examples of the alkali include sodium hydroxide, potassium hydroxide, calcium hydroxide, quaternary ammonium salt hydroxide, sulfonium salt hydroxide, and strong bases. Ion exchange resins (OH type) and the like can be used, and sodium hydroxide, potassium hydroxide, and strongly basic ion exchange resins are preferably used. Sulfonium bases are sensitive to heat, light, ultraviolet rays, strong basic conditions, etc., and desulfonium saltation occurs gradually after polymerization, making it impossible to effectively substitute alkoxy groups. Therefore, the condensation polymerization reaction is carried out at relatively low temperatures, i.e. Below 25℃, especially below 5℃, and even -10
Preferably, the reaction is carried out at a temperature below .degree.
The reaction time may be appropriately determined depending on the polymerization temperature and is not particularly limited, but is usually within the range of 1 minute to 50 hours. According to this production method, after polymerization, the polymer precursor is first converted into a sulfonium salt, i.e.

It is produced as a high molecular weight polyelectrolyte (polymer sulfonium salt) having [Formula] in its side chain, but the sulfonium salt side chain reacts with alcohol (R ₁ OH) in the solvent, and the alcohol's alkoxy group [Formula ( )In
corresponding to OR ₁ ] becomes the side chain. Therefore, it is essential that the solvent used contains an alcohol corresponding to the above R ₁ OH. These alcohols may be used alone or in combination with other solvents. The solvent to be mixed is not particularly limited as long as it is soluble in alcohol, but water is particularly preferred. Regarding the mixing ratio when using a mixed solvent, it is sufficient as long as alcohol is present, but preferably 5
weight percent or more. Note that R ₁ is an alkyl group having 1 to 10 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n
-butyl, 2-ethylhexyl, phenyl, cyclohexyl groups, etc., but hydrocarbon groups having 1 to 6 carbon atoms, particularly methyl and ethyl are preferred. In the substitution reaction with alkoxy, after polymerization, it is effective to raise the temperature in a solvent containing alcohol to a temperature higher than the polymerization temperature in promoting substitution with alkoxy groups. When the polymerization solvent contains the above-mentioned alcohol, an alkoxy group substitution reaction can be performed subsequent to the polymerization. On the other hand, when the polymerization solvent is water or the like and does not contain alcohol, the same procedure can be carried out by mixing alcohol after polymerization. In the substitution reaction with an alkoxy group, the temperature is preferably 0°C to 50°C, more preferably 0°C to 50°C from the viewpoint of reaction rate.
~25℃. Since polymers having alkoxy groups in their side chains are generally insoluble in the mixed solvent used, they precipitate as the reaction progresses. Therefore, it is effective to carry out the reaction until sufficient precipitation occurs, preferably 15 minutes or more, more preferably 1 hour or more. In this way, the polymer precursor having an alkoxy group in its side chain is separated by filtering the precipitated product. In order to obtain a polymer precursor that provides high conductivity, it is preferable that the molecular weight is sufficiently large, and a polymer precursor having at least 2 units or more, preferably 5 to 50,000 units of repeating structure of the general formula (), e.g. Those having a molecular weight that cannot be dialyzed by dialysis treatment using a dialysis membrane having a molecular weight cutoff of 3500 or more are effectively used. The feature of the present invention is that the polymer precursor having an alkoxy group in the side chain is insoluble in water, but soluble in organic solvents such as dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, and chloroform; Moldings of any shape can be made from a solution, and the poly-2,5-thienylenevinylene produced after the elimination reaction of the alkoxy group provides high conductivity through doping. Any method can be used to obtain the polymer molded article. Regarding its form, for example, a film, fiber, coating film, or any other molded product can be selected. A particularly useful molding method is a method using a polymer precursor solution, which is then formed into a film by casting or into fibers by solution spinning, and a method in which the solution is applied to a substrate.
At this time, it is preferable to use a polymer precursor solution from which low molecular weight substances or terminal reactants have been removed by dialysis treatment or reprecipitation treatment. 2,5-thienylenevinylene can be produced by eliminating the alkoxy group of the polymer precursor. The treatment for eliminating the alkoxy group can be carried out by applying conditions such as heat, light, and ultraviolet rays, but heat treatment is preferable. Moreover, it is preferable that the elimination treatment of the alkoxy group of the polymer precursor is performed in an inert atmosphere. The inert atmosphere here refers to an atmosphere that does not cause deterioration of the polymer during processing, and is generally carried out using an inert gas such as nitrogen, argon, helium, etc. You may also do so. When removing alkoxy groups by heat,
Heat treatment at too high a temperature produces poly-2,5-
The treatment temperature is usually 0°C to 400°C, preferably 50°C, since it leads to decomposition of thienylene vinylene and the formation reaction is slow and impractical at low temperatures. More preferably, the temperature is 100°C to 320°C. Further, the treatment time can be appropriately selected depending on the treatment temperature, but a range of 1 minute to 10 hours is industrially practical. The poly-2,5-thienylene vinylene produced in this manner contains 2,5-thienylene vinylene as a main structural unit. According to the production method of the present invention, it is possible to produce poly-2,5-thienylene vinylene having only conjugated repeating units of 2,5-thienylene vinylene, and also to produce poly-2,5-thienylene vinylene having only conjugated repeating units of 2,5-thienylene vinylene. It is also possible to produce polymers that partially contain a thienylene ethylene skeleton as a constituent unit. In other words, the infrared absorption spectrum shows that in the polymer after insufficient elimination treatment, there are still structural units having a 2,5-thienylene ethylene skeleton in which the alkoxy group is incompletely eliminated. It is observed by et al. In this case, a highly flexible poly-2,5-thienylene vinylene can be produced. Note that the ratio of 2,5-thienyleneethylene units to 2,5-thienylenevinylene units can be changed by arbitrarily devising the manufacturing conditions depending on the purpose of use. For purposes such as conductive polymer materials, the ratio of the latter to the former is preferably 1 or less, more preferably 1/20 or less. It is also possible to heat-treat a molded product of a polymer precursor by stretching and orienting it. These stretching and orientation treatments can be performed before or simultaneously with the alkoxy group elimination treatment. Orientation can be achieved by devising a molding method, such as extrusion using high shear force, but high orientation can be imparted by heating and stretching a polymer precursor molded product from a polymer precursor solution. The extent of this stretching orientation can be confirmed by the appearance of infrared dichroism in a polarized infrared spectrum. Next, the poly-2,5-thienylene vinylene obtained by the alkoxy group elimination treatment in the present invention is treated with an electron acceptor or an electron donor (referred to as a dopant) to give a highly conductive composition. As the dopant, known conductive polymer compounds, such as doping with polyacetylene, or compounds that have been found to have an effect of improving conductivity by forming an interlayer compound of graphite, can be effectively used. Even if the poly-2,5-thienylene vinylene obtained in the present invention is not oriented, it can be doped to provide a highly conductive composition having a conductivity of 20 S/cm or more. <Effects of the Invention> As explained above, by using the novel polymer precursor of the present invention, it is possible to obtain a material with much higher conductivity than the conventional poly-2,5-thienylenevinylene, In addition, the present invention can produce poly-2,5-
Thienylene vinylene is provided. <Example> The present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. After dissolving 7.8 g of 2,5-thienylene-bis(methylenedimethylsphonium bromide) in 200 ml of a mixed solution of ion-exchanged water and methanol (volume ratio 1:1), 20 ml of 1N NaOH and 80 g of methanol were dissolved.
ml was added dropwise over 30 minutes at -30°C, and after the dropwise addition, stirring was continued at -30°C for 30 minutes. This reaction solution is quickly passed through a dialysis membrane (cellotube, molecular weight fractionator).
8000 (manufactured by Union Carbide) and immersed in a water-methanol mixed solution (1:1) cooled to 0°C for 1 day of dialysis treatment, a yellow precipitate was formed within the dialysis membrane. This precipitate was dissolved in dimethylacetamide, cast, and dried under a nitrogen stream to obtain a precursor film. The following elemental analysis results were obtained for this precursor film.

[Table] The calculated values are the values when the methoxy group is the side chain, and the calculated values are the values when the sulfonium salt is the side chain. In addition, when dissolved in deuterium-substituted dimethyl sulfoxide and measured for H-NMR and ¹³ C-NMR, H-NMR showed 6.7 ppm, 4.5 ppm,
A proton signal was seen around 3.2ppm,
Other signals were unclear due to water and solvent. On the other hand, in ¹³ C-NMR, 38ppm, 56ppm, 79ppm,
Signals were observed at 125ppm, 140ppm, and 142ppm. In the infrared absorption spectrum, ether bond absorption was observed at 1100 cm ^-1 . From these analysis results, it was confirmed that the precursor polymer had a methoxy group in its side chain. Example 1 The precursor film obtained in Reference Example 1 (length 2
cm, width 1 cm) was subjected to stationary heat treatment at 100° C. for 30 minutes under a nitrogen atmosphere using a horizontal tubular furnace to obtain a black poly-2,5-thienylene vinylene film with golden luster. This structure was confirmed because the elemental analysis values and the characteristic absorption in the infrared absorption spectrum matched those of the specimen obtained by the Wittig method. When the gas generated during heat treatment of the precursor polymer film was analyzed using a quadrupole mass spectrometer, only a signal with a mass number of 32, which is thought to be methyl alcohol, was observed. Reference Example 2 When the poly-2,5-thienylene vinylene film obtained in Example 1 was doped with iodine, which is an electron acceptor compound, from the gas phase at room temperature by a conventional method, the film was doped in 6 hours. It showed an electrical conductivity of 374S/cm. The electrical conductivity was measured using the four-terminal method. Reference Example 3 When the poly-2,5-thienylene vinylene film obtained in Example 1 was doped with sulfur trioxide using 30% oleum as a source, 124S/
The conductivity was cm. Reference Example 3 Using the poly-2,5-thienylene vinylene film obtained in Example 1 as an electrolyte, 0.5N LiC10 ₄ −
When electrolytic doping was performed using an acetonitrile solution, the resulting film had a glossy black color and an electrical conductivity of 151 S/cm. Example 2 A dimethylacetamide solution of the poly-2,5-thienylene vinylene polymer precursor obtained by the method described in Reference Example 1 was cast on a polyethylene film,
A cast film was obtained by drying in a nitrogen stream. This film was stretched up to 6 times at 80 DEG C. or higher and heat treated at 200 DEG C. for 1 hour under load to obtain a stretched poly-2,5-thienylene vinylene film. This film exhibits infrared dichroism,
It was found that it was oriented. Reference Example 4 The film obtained in Example 2 was doped with iodine in the same manner as in Reference Example 2, and exhibited a high electrical conductivity of 2110 S/cm. Furthermore, when the anisotropy of the electrical conductivity was measured by the Montgomery method, an anisotropy of 30 or more was observed, and an improvement in the electrical conductivity was observed in the stretching direction. Reference Example 5 (Production of precursor of poly-2,5-thienylene vinylene) After dissolving 4.3 g of 2,5-thienylene-bis(methylenedimethylsphonium bromide) in 50 ml of a mixed solvent of ion-exchanged water and ethanol, Cooled to -30°C. Next, a strongly basic ion exchange resin (Amberlite IRA-401, manufactured by Rohm and Haas), which had been converted into the OH form in advance in an amount equivalent to twice the amount of the sulfonium salt, was gradually added over 10 minutes, and the mixture was heated at -30°C. Stirring was continued for 50 minutes. After the reaction, the reaction solution was separated from the ion exchange resin, and the filtrate was heated to 0°C and left at 0°C for 10 hours, resulting in a yellow precipitate. This precipitate was dissolved in dimethylacetamide and reprecipitated with water. The obtained precipitate was dissolved in dimethylacetamide,
I got cast film. This precursor film was heated using deuterium-substituted dimethyl sulfoxide as a solvent.
- When the NMR spectrum was measured, a signal of the methyl proton of the ethoxy group was observed at 1.1 ppm. Example 3 The polymer precursor film obtained in Reference Example 5 was heated and stretched to 200°C under nitrogen flow to obtain a poly-2,5-thienylene vinylene stretched film stretched five times. . The characteristic absorption of the infrared absorption spectrum of this film matched that obtained in Example 1, and it was found that it exhibited infrared dichroism and was oriented. Example 4 3.9 g of 2,5-thienylene-bis(methylenedimethylsphonium bromide) was dissolved in 50 ml of a mixed solvent of ion-exchanged water and methanol (volume ratio 1:1), and then 0.4 g of NaOH was dissolved in water. - 50 ml of methanol solution was added dropwise at -30°C over 30 minutes, and after the dropwise addition, stirring was continued at -30°C for 30 minutes. The temperature was then raised to 0°C, and the reaction was continued at 0°C for 10 hours, resulting in precipitation. The reaction solution containing this precipitate was filtered through a dialysis membrane (Cerotube, molecular weight fraction 8000, manufactured by Union Carbide).
water-methanol mixed solvent (1:
1) was subjected to dialysis treatment for 10 hours to remove soluble low molecular weight substances and impurities. Thereafter, this precipitate was subjected to solid-liquid separation. This precipitate is insoluble in water;
It was soluble in organic solvents. The H-NMR spectrum and C ¹³ − of this polymer
When the NMR spectrum was measured using deuterium-substituted dimethyl sulfoxide as a solvent, a signal of methoxy group was observed. From this result, it was found that the polymer precursor obtained had a methoxy group in the side chain. The resulting precipitate was dissolved in dimethylacetamide, cast, and dried at room temperature under a nitrogen stream. A yellow polymer precursor film with a thickness of 20 μm was obtained. Polymer precursor film is 5cm long and 3cm wide.
The film was cut into strips, immersed in a mixed solution of water containing 40% dimethylacetamide, slowly stretched to 4.7 times the length before dipping, the dimethylacetamide/water mixed solvent was drained, and the film was placed under a nitrogen stream. Dry. This film was heat-treated at 100 to 300°C and stretched to 1.1 times in a nitrogen atmosphere using a horizontal tube furnace to obtain a black 5.2 times uniaxially stretched poly-2,5-thienylene vinylene film with metallic luster. . The thickness of this film was approximately 10 μm. Reference Example 6 When the film obtained in Example 4 was doped with iodine, which is an electron acceptor compound, from the gas phase at room temperature by a conventional method, the film was doped in 18 hours.
It showed an electrical conductivity of 2550S/cm. Furthermore, when the electrical conductivity was measured in the direction parallel and perpendicular to the stretching direction, the anisotropy of the electrical conductivity was 35 or more. Example 5 3.9 g of 2,5-thienylene-bis(methylenedimethylsphonium bromide) was dissolved in 200 ml of a mixed solvent of ion-exchanged water and ethanol (volume ratio 1:1), and then dissolved in 20 ml of 1N NaOH and ethanol.
80ml of the mixed solution was added dropwise over 30 minutes at -30℃,
After dropping, stirring was continued for 30 minutes at -30°C. This reaction solution was filtered using a dialysis membrane (Cerotube, molecular weight fraction 8000, manufactured by Union Carbide).
When dialysis treatment was performed for one day against a water-ethanol mixed solvent (1:1) at °C, a precipitate was generated. This precipitate was separated into solid and liquid. This precipitate was insoluble in water and soluble in organic solvents. H- of this polymer
When NMR spectra and C ¹³ -NMR spectra were measured using deuterium-substituted dimethyl sulfoxide as a solvent, signals of ethoxy groups were observed. The results showed that the obtained polymer precursor mainly had ethoxy groups in the side chains. Since the alkoxy groups of the polymer vary depending on the type of alcohol used for polymerization, it is presumed that the alcohol reacts with the sulfonium base. The resulting precipitate was dissolved in dimethylformamide, cast, and dried at room temperature under a nitrogen stream. A yellow polymer precursor film with a thickness of 21 μm was obtained. Polymer precursor film is 5cm long and 3cm wide.
Cut into strips, soak in a water mixed solvent containing 30% by weight of dimethylformamide, and gently cut to the same length as before soaking.
The film was stretched to 3.5 times, the dimethylformamide/water mixed solvent was discharged, and the film was dried under a nitrogen stream. This film was heat-treated and stretched to 1.6 times in a nitrogen atmosphere using a horizontal tube furnace at 100 to 300°C to obtain a black 5.6 times uniaxially stretched poly-2,5-thienylene vinylene film with metallic luster. . The thickness of this film was approximately 8 μm. Reference Example 7 When the film obtained in Example 6 was doped with iodine, which is an electron acceptor compound, from the gas phase at room temperature by a conventional method, the film was doped in 20 hours.
It showed an electrical conductivity of 2630S/cm. Furthermore, when the anisotropy of the electrical conductivity was measured by the Montgomery method, an anisotropy of 40 or more was observed, indicating an improvement in the electrical conductivity in the stretching direction.

Claims (1)

[Claims] 1 Substantially general formula (1) _R1 : A method for producing poly-2,5-thienylenevinylene, which comprises subjecting a polymer precursor to an elimination treatment to remove an alkoxy group consisting of a repeating unit represented by an alkyl group having 1 to 10 carbon atoms.