JPH0796610B2 - Method for producing modified conductive polypyrrole molded article - Google Patents

Description

TECHNICAL FIELD The present invention relates to a modified polypyrrole molding for a conductive organic material.

<Prior art> Organic conductive materials have made remarkable progress in recent years, and their characteristics are that they can be used not only as materials for electronic devices such as wiring materials, electromagnetic shields, and sensors, by taking advantage of their advantages such as mass production, moldability, and light weight. , It is becoming important to apply to molecular electronics such as molecular devices, which are expected to surpass current silicone-based devices.

One of these materials is a conductive polymer derived from oxidative polymerization (chemical or anodic electrolytic) of a heteroaromatic compound. During this polymerization, the counterions introduced into the polymer and exhibiting conductivity are derived from the ions constituting the electrolyte in the polymerization solution. The mechanical, electrical, and chemical properties of conducting polymers are greatly affected by the type of counterions introduced (J. Polymer Science, Poly
mer Physics Edition, 33 (1984), Synthetic Metals, 2
6 , 209 (1988)).

For example, mechanical properties include stretchability and tensile strength / elongation of the formed film, electrical properties include electrical conductivity, and chemical properties include thermal stability and long-term stability.

In practical use, it is sufficient that the conductive polymer simultaneously satisfies all of these properties so as to be suitable for the use, but this is not always the case.

For example, when perchlorate is used as the counter ion of a conductive polymer, the mechanical properties of the polymer are almost satisfied, but the thermal properties are unstable, and hexafluorophosphate, hexafluoroarsenate, In the case of hexafluoroantimonate and the like, the mechanical and electrical properties are almost good, but it is not necessarily suitable for application from the viewpoints of oxidizability, toxicity and hygroscopicity.

Therefore, there has been a demand for a technique of obtaining a polypyrrole molded article having preferable characteristics such as electrical properties and imparting new preferable characteristics while maintaining the characteristics.

<Problems to be Solved by the Invention> The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a modified polypyrrole molded article that exhibits excellent properties as a conductive material.

PF ₆ The invention free <Means for Solving the Problems> ^- in the presence of, and producing a polypyrrole shaped material by electrolytic oxidation polymerization, and then the counterion PF ₆ of the polypyrrole molded body ^- and ion size A method for producing a modified electrically conductive polypyrrole molded article, characterized in that it is exchanged with another anion of 10 Å or less.

Hereinafter, specific contents of the present invention will be described in detail.

First, a polypyrrole molded article of the present invention that imparts high mechanical properties and electrical properties is subjected to potentiostatic electrooxidative polymerization in the presence of an electrolyte using pyrrole and / or a derivative thereof as an organic solvent containing water as necessary. It is obtained by precipitating on an anode plate by (JCSChem.Comm., 197
9,635). According to this method, anions coexisting in the reaction system are taken in as a dopant, so that high conductivity is exhibited without newly doping an electron-accepting compound.

Pyrrole and its derivatives used in the present invention are
Those having a high degree of purity are preferable, and it is desirable to use them as distillation purification before use. As the derivative of pyrrole, a substitution product at the N position of the pyrrole ring, a mono substitution product at the β position of the pyrrole ring,
A β-, γ-position 2-substituted product or the like is used, and specific examples thereof include N-alkylpyrroles such as pyrrole, N-methylpyrrole and N-ethylpyrrole, N-phenylpyrrole, 3-
Examples thereof include 3-alkylpyrrole such as methylpyrrole, and 3,4-dialkylpyrrole such as 3,4-dimethylpyrrole.

Pyrrole or its derivative is 0.0001 mol / solvent
Polymerization is carried out using liters (M) to 1M, preferably 0.001M to 0.5M.

Examples of the electrolyte include tetraalkylammonium salts of inorganic acids of hexafluorophosphate, alkali metal salts, and the like. Specific examples include tetramethylammonium salt, tetraethylammonium salt, tetrapropylammonium salt, tetrabutylammonium salt of hexafluorophosphate, and further lithium salt, sodium salt, potassium salt and the like. Of these, tetramethylammonium hexafluorophosphate and tetrabutylammonium hexafluorophosphate are particularly preferable. However, it is not limited to these.

The electrolyte is 0.0001M to 1M with respect to the solvent, preferably 0.001M
~ 0.5M is used.

As the organic solvent that is a polymerization solvent, acetonitrile, benzonitrile, nitrobenzene, tetrahydrofuran,
It is preferable to use nitromethane, propylene carbonate, ethylene carbonate, sulfolane, dimethoxyethane, or the like, which easily dissolves the electrolyte, but is not necessarily limited thereto.

The proportion of water used if desired enhances the effect of the electrolyte,
This is to improve the form of polypyrrole precipitation.
The amount used depends on the type of electrolyte used, and the concentration of water in the electrolyte solution is 0.1M to 5M, preferably 0.3M to 3M.

Next, the electrolytic polymerization conditions are as follows.

The anode material used in the reaction is defective in the electrode reaction,
A general-purpose material may be used as long as it does not deteriorate, and is not particularly limited, but a metal such as platinum, gold, copper, nickel, or a conductive material similar to these, a carbon electrode, or the like is used. In addition, when the electrode area of the anode is larger than that of the anode, the state of deposition of polypyrrole generally produced is better. The ratio of the cathode to the anode surface area is 1.1 times or more, preferably 1.5 times or more, more preferably 2 times or more, and particularly preferably 3 times or more.

The electrolysis potential is 0.7 V or higher with respect to a silver / silver chloride (Ag / AgCl) reference electrode. Suitably 0.8 to 1.2 volts are used, particularly preferably 0.9 to 1.1 volts. A KCl / agar salt bridge or the like is used to suppress the electrolysis potential at a low temperature of 0 ° C. or lower. Any method may be used as long as the electrolytic potential can be controlled. The electrolysis current, as the current density at the anode, is 0.01 mA / cm ^{2 to} 10 mA / cm ² , preferably 0.05 mA / cm ² to
It is 5 mA / cm ² .

The polymerization temperature is 0 ° C. or lower, and −20 ° C. or lower is preferably adopted. The lower the temperature is, the more the molded body exhibits high conductivity at room temperature, which is preferable, but the temperature must be higher than the melting point of the electrolytic solution (JP-A-59-140027). On the other hand, if it is higher than 0 ° C, sufficient electric conductivity cannot be obtained, which is not preferable.

Next, the counterions of the polypyrrole molded product thus obtained are exchanged by immersing the polymer molded product in an electrolytic solution prepared by dissolving an electrolyte consisting of anions to be exchanged in an organic solvent.

Examples of the electrolyte include tetraalkylammonium salts of inorganic and organic acids, alkali metal salts of inorganic and organic acids, and the like.

Of these, preferred electrolytes for the present invention are those in which the anion constituting the electrolyte has an ionic size of 10 Å or less. Specifically, tetramethylammonium nitrate (NO ₃ ^- Size: 4.5 Å), tetrabutyl ammonium hydroxide diene sulphate (HSO ₄ ^- Size: 5.1 Å), tetraethylammonium tetrafluoroborate (BF ₄ ^- Size: 5.3
Å), tetramethylammonium hexafluorophosphate (PF ₆ ^- Size: 5.9 Å), tetraethylammonium trifluoromethanesulfonate (CF ₃ SO ₃ ^- Size: 6.
0Å), tetraethylammonium perchlorate (ClO
₄ ^- Size: 6.2 Å), tetraethylammonium nonyl perfluorobutane sulfonate (C ₄ F ₉ SO ₃ ^- Size: at 7.9 A),
Tetraethylammonium tosylate Can be given. However, it is not limited to these.

Here, the counterion size is the length in the long axis direction of the molecule including the ionized atom, and is described in the Handbook of Chemistry (Basic Edition II, Revised 2nd Edition, pp. 1407 to 1408, Nihon Kagaku ed. It is a value calculated by referring to the above.

The electrolytic mass in the immersion solvent may be at least an amount equal to or more than the counter ion contained in the immersed polypyrrole molded article. It is preferably 5 times or more, more preferably 10 times or more.

As the organic solvent that is the immersion solvent, acetonitrile, benzonitrile, nitrobenzene, tetrahydrofuran,
Preferred are those that easily dissolve the electrolyte such as nitromethane, propylene carbonate, ethylene carbonate, sulfolane, dimethoxyethane, and water, and swell polypyrrole. Particularly preferred are propylene carbonate and water. It is not limited to those listed here.

Immersion temperatures are preferably higher than lower for counterion exchange. However, if it is too high, unfavorable reactions such as side reactions occur, so that the temperature is preferably 50 ° C or lower.

Stirring of the dipping solution during dipping may be performed with a shaker, an ultrasonic oscillator, or the like, or may be non-stirring.

The immersion time for 100% counterion exchange is determined by the above immersion conditions. For example, when the electrolyte concentration and temperature are high and the immersion is carried out under stirring, counter ions can be sufficiently exchanged in a shorter immersion time than in the opposite case.

Under the above-mentioned immersion conditions, substantially 100% counterion exchange is carried out, and a polypyrrole molded article having improved stability can be obtained without changing the electrical properties.

<Effect of the Invention> According to the present invention, it is possible to obtain a modified conductive polypyrrole molded article having excellent stability while maintaining excellent mechanical and electrical properties. Such a molded product is useful for many applications such as molded products such as wiring materials, electromagnetic shields and molecular electronic members.

<Examples> The present invention will be described in detail below with reference to Examples. However, the present invention is not limited to this.

Examples 1, 2 and Comparative Examples (1-5) Freshly distilled propylene using a glass-like carbon plate (GC-20 made by Tokai Carbon Co., Ltd.) whose surface was polished as a positive electrode in a 500 ml separable flask and a platinum foil as a negative electrode. A mixed solution of 400 ml of carbonate and 4 ml of water and 5.24 g (0.024 mol) of tetramethylammonium hexafluorophosphate were added, and nitrogen gas was introduced to perform deoxidation. Thereafter, 1.61 g (0.024 mol) of pyrrole was added.

Cooled to -30 ℃, under nitrogen stream, 1.0V against Ag / AgCl electrode
Electrolytic oxidative polymerization was carried out for 24 hours (current amount 425 clones). The 30 μm film produced after the completion of the polymerization was peeled off from the anode plate.

Then the release film (2.5cm × 2cm × 30μm), PF 6 - of about 0.01 g) content, counterion content contained therein 3
Contains electrolyte of 0 times moles of various ions (Example 1: nonylfluorobutane sulfonate, Example 2: tosylate)
It was immersed in 60 ml propylene carbonate at 20 ° C. for 48 hours.

The results obtained are shown in Table 1.

Comparative Example 1 is a polypyrrole film before exchange (counterion P
Indicating) the results ^- F _6.

Comparative Examples 2 and 3 respectively ^{_{counterion, nC 4 F 9 SO 3 -}} , The results obtained by direct polymerization using are shown below. The electric conductivity is shown in comparison with the value in Comparative Example 1.

As can be seen from Table 1, the molded body obtained using counterions used for directly exchange polymerization PF ₆ ^- conductivity than the molded body was prepared in the presence of but down, using the latter in the former It can be seen that by exchanging with the counter ion, the electric conductivity is completely retained and the electric conductivity is not lowered under reduced pressure and the stability is excellent.

Furthermore, when the exchange counterion size was larger than 10Å, the exchange rate was not satisfied.

Claims (1)

[Claims] 1. A polypyrrole molded article is produced by electrolytic oxidation polymerization in the presence of free PF ₆ ⁻ , and then the counter ion PF ₆ ⁻ in the polypyrrole molded article is mixed with another anion having an ion size of 10 Å or less. A method for producing a modified electrically conductive polypyrrole molded article, characterized in that it is replaced.