JP2895546B2 - Water-insoluble self-doping conductive polymer and method for producing the same - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a water-insoluble self-doping conductive polymer having improved water and solvent resistance, excellent electrical and mechanical properties, and a method for producing the same. About.

[Prior art] Among conductive polymers, Japanese Patent Application No. 1-9063 and Proceeding of the ACS Division.
Of Polymeric Materials: Science and Engineering, Los Angeles, CA, USA (Proceedings of the ACS Division of P
olymeric Materials: Science and Engineering) No. 59
Vol., P. 1164 (Autumn Meeting, 1988) has a self-doping conductive polymer in which a large anionic group with slow diffusion is previously covalently bonded to the main chain to which π electrons are conjugated. It has a unit structure, and this adjacent anionic group quickly acts as a dopant in the oxidation-reduction process of a π-electron conjugated system.

In the oxidation-reduction reaction of the conductive polymer, protons of sulfonic acid are released, which is in principle different from the conductive mechanism involving the process of transferring an anionic dopant which is observed in a conventional conductive polymer. That is, in the process of doping a conductive polymer having a self-doping function, a proton having a small ionic radius moves, so that the proton can easily and quickly move in the conductive polymer, but in a conventional conductive polymer having no self-doping function, Since the moving dopant has a large ionic radius, the response speed is rate-determining.

In other words, a conductive polymer having a self-doping function via transfer of small protons is expected to have a very high response speed. For details, see JP-A-63-39916
Reference can be made.

In addition, since the conductive polymer having the self-doping function is soluble in water and has a characteristic that it can be easily formed and formed into an arbitrary shape, a large-area film can be easily formed. Also, it has a feature that it has extremely excellent workability even for electric elements that require fine processing.

However, in general, a solvent for an electrochromic device that applies these characteristics often uses a solvent as a drive system. There is a problem that the performance is remarkably reduced due to a change with time.

In the application as a conductive film with a large area,
Since this polymer is water-soluble, there is a problem that its properties are significantly affected even by humidity in the air.

[Problems to be Solved by the Invention] A conductive polymer having a self-doping function has a high response speed to a redox reaction and a high electrochemical activity, so that it is excellent as an electrode of a secondary battery and as an eletatrochromic display element. Although it is naturally expected to have such properties, it has a problem that its properties are remarkably deteriorated due to its environmental influence, for example, a solvent system or moisture due to its water solubility.

In order to solve these problems, improvement of water resistance of the self-doping type conductive polymer has been urgently required.

[Means for Solving the Problems] The self-doping conductive polymer is a water-soluble polymer, and is highly evaluated as a material that is particularly excellent in manufacturing safety in an industrial film-forming process and a molding process. .

As a result of thorough studies to respond to these industrial needs, we investigated the improvement of moisture resistance and water resistance, which had been problems in the past, and surprisingly, water-soluble conductive polymer with self-doping function Then, they have found that a compound having a structural unit represented by the following general formulas (I) and (II) becomes water-insoluble while having a self-doping function and conductivity, and has completed the present invention.

That is, the present invention provides (1) a water-insoluble self-doping conductive polymer having a structure represented by the following general formula (I) or (II): In the formula, Ht is NH, S, O, Se or Te, and R is a linear or branched divalent hydrocarbon group having 1 to 10 carbon atoms or a divalent hydrocarbon group containing an ether bond. And
X is SO ₃ or CO ₂ .

Z ₁ is RX-H, Z ₂ is 'a, R' RX-H, H or OR represents an alkyl group with a linear or branched having 1 to 10 carbon atoms. The polymerization degree n is 10 or more.

(2) a method of producing a water-insoluble self-doping polymer for dehydrating a water-soluble conductive polymer having a structure represented by the general formula (I) or (II), and (3) a general formula A water-soluble conductive polymer having a structure represented by (I) or (II) and having a self-doping function is dehydrated to reduce the water content to less than 5% (2)
The present invention relates to a method for producing the water-insoluble self-doping conductive polymer described above.

Examples of the water-insoluble self-doping conductive polymer belonging to the general formula (I), which is the object of the present invention, include thiophen-3- (2-ethanesulfonic acid) and thiophen-3-
(3-propanesulfonic acid), thiophen-3- (4-
Butanesulfonic acid), thiophen-3- (5-pentanesulfonic acid), thiophen-3- (6-hexanesulfonic acid), thiophen-3- (7-heptanesulfonic acid), thiophen-3- (2-methyl- 3-propanesulfonic acid), thiophen-3- (2-methyl-4-butanesulfonic acid), thenylsulfonic acid, 2- (3-thienyloxy) ethanesulfonic acid, 3- (3-thienyloxy) propanesulfonic acid , 4- (3-thienyloxy)
Butanesulfonic acid, 2- (3-thenyloxy) ethanesulfonic acid, 3- (3-enyloxy) propanesulfonic acid, 2- [2- (3-thienyloxy) ethoxy] ethanesulfonic acid, 3- [2- (3 -Thienyloxy) ethoxy] propanesulfonic acid, furan-3- (2-ethanesulfonic acid), furan-3- (3-propanesulfonic acid), furan-3- (4-butanesulfonic acid), furan-3- (5-pentanesulfonic acid), furan-3- (6
-Hexanesulfonic acid), pyrrole-3- (2-ethanesulfonic acid), pyrrole-3- (3-propanesulfonic acid), pyrrole-3- (4-butanesulfonic acid), pyrrole-3- (5-pentane Sulfonic acid), pyrrole-3
-(6-hexanesulfonic acid), selenophene-3-
(2-ethanesulfonic acid), selenophene-3- (3-
Propanesulfonic acid), selenophene-3- (4-butanesulfonic acid), selenophene-3- (5-pentanesulfonic acid), selenophene-3- (6-hexanesulfonic acid), tellurphen-3- (2-ethanesulfonic) Acid), tellurphen-3- (3-propanesulfonic acid), tellurphen-3- (4-butanesulfonic acid),
Examples thereof include polymers obtained from monomers such as tellurphen-3- (5-pentanesulfonic acid) and tellurphen-3- (6-hexanesulfonic acid).

Examples of the water-insoluble self-doping conductive polymer belonging to the general formula (II) include 2-methoxy-5- (propyloxy-3-sulfonic acid) -1,4-phenylenevinylene and 2-ethoxy-5- ( Propyloxy-3-sulfonic acid) -1,4-phenylenevinylene, 2-propyloxy-5- (propyloxy-3-sulfonic acid) -1,4-
Phenylene vinylene, 2-butyloxy-5- (propyloxy-3-sulfonic acid) -1,4-phenylenevinylene, 2-butyloxy-5- (propyloxy-3-sulfonic acid) -1,4-phenylenevinylene, 2 , 5-Bis (propyloxy-3-sulfonic acid) -1,4-phenylenevinylene, 2,5-bis (ethyloxy-2-sulfonic acid)
1,4-phenylenevinylene, 2,5-bis (butyloxy-4-sulfonic acid) -1,4-phenylenevinylene, 5-
(Propyloxy-3-sulfonic acid) -1,4-phenylenevinylene, 5- (ethyloxy-2-sulfonic acid)-
1,4-phenylenevinylene, 5- (butyloxy-4-
Sulfonic acid) -1,4-phenylenevinylene and polymers of structural units such as 5- (pentyloxy-4-sulfonic acid) -1,4-phenylenevinylene can be exemplified.

This water-insoluble self-doping type conductive polymer is obtained by simply dehydrating a conventionally known water-soluble conductive polymer having a self-doping function represented by the general formula (I) or (II). Can be obtained by

As will be described later in detail in Examples, there is a difference in moisture resistance and water solubility between each of the water-insoluble and water-soluble polymers, but other properties such as ultraviolet-visible-near infrared. Absorption, electric conductivity, X-ray diffraction pattern, thermal analysis (TG-DTA), etc. showed no substantial difference between the two, and the reason why water resistance was based on the above analysis means Some are completely unknown.

However, before the dehydration treatment, the conductive polymer that dissolves in water very easily is a polymer that does not dissolve in cold water, and even if it is extracted with hot water using a Soxhlet, it does not even swell depending on the method of dehydration treatment. , Even to polymers with water resistance.

Among these water-insoluble self-doping conductive polymers, low molecular weight polymers such as those in which n is less than about 10 in the general formulas (I) and (II) have low conductivity per se and have low electrochemical activity. With poor water resistance. Therefore, a conductive polymer having a water-soluble self-doping function in which n is at least 10 or more should be used as a raw material.

As a dehydration treatment, in a vacuum desiccator such as silica gel or alumina at room temperature, it is necessary to treat the film as a film of 3 μm or less for a minimum of 5 days or more.
℃, in a vacuum of about 10 ^-3 mmHg, to obtain water resistance of about 30 minutes to 3 hours that does not dissolve in cold water, but by dehydrating in a vacuum of 120 ℃, about 4 to 5 hours, A water-resistant conductive polymer that does not swell against Soxhlet extraction for 12 hours can be obtained.

Care must be taken when the temperature of the dehydration treatment is 150 ° C. or more, since the conductive polymer may be deteriorated.

As can be seen from the above description, the weak dehydration treatment swells or dissolves in high-temperature water even though it has water resistance to cold water. As the degree of dehydration increases, swelling disappears, and it tends not to dissolve even at high temperatures.

This is not fixed depending on the type, degree of polymerization, shape, and the like of the polymer, but generally, the higher the molecular weight, the more the shape of the film tends to be insoluble than the shape of the powder.

For example, a dehydration treatment at 100 ° C. to 150 ° C. is effective for imparting water resistance sufficient to endure Soxhlet extraction.
The self-doping type conductive polymer that has become water-insoluble by such dehydration treatment seems to have no change in other physical properties without de-doping just because it has become water-insoluble. It is surprising that no change was seen.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the following Examples do not limit the scope of the present invention.

The conductive polymer having a water-soluble self-doping function used in the present example and the comparative example is represented by the general formula (I)
And (II) are polymers having a structure having X = SO ₃ , specifically, the following formulas (Ia) and (IIa)
It has a structure shown by.

However, (Ia) is a poly "thiophen-3- (3-propanesulfonic acid)", the production method of which is described in the aforementioned Japanese Patent Application No. 1-9063, and (IIa) is a poly "2- (2-propanesulfonic acid)". Methoxy-5- (propyloxy-3-sulfonic acid) -1,4
-Phenylene vinylene "and its manufacturing method is based on the Proceedings of the ACS Division.
Of Polymeric Materials: Science and Engineering, Los Angeles, CA, USA (Proceedings of the ACS Division of P
olymeric Materials: Science and Engineering) No. 59
Volume, p. 1164 (1988, Fall Meeting).

The average molecular weight of (Ia) is Mw = 1 × 10 ⁵ (measured by GPC in terms of pullulan), and (IIa) is Mw =
1.4 × 10 ⁵ (same as above) was used.

These conductive polymers having a water-soluble self-doping function were dissolved in water and formed into a film by a spin coater.

The structural analysis of the conductive polymer having a water-soluble self-doping function and the water-insoluble self-doping conductive polymer was performed by the following analysis means. The electrical conductivity was measured by a four-terminal method after pressing the sample to a thickness of about 1 mm, cutting the sample to a size of 2 mm × 10 mm.

The measurement of the ultraviolet-visible-near-infrared absorption spectrum was performed using a self-recording spectrophotometer 330 manufactured by Hitachi, Ltd.

For evaluation of the electrochemical characteristics, cyclic voltammetry manufactured by Hokuto Denko KK was used.

The measurement of the X-ray analysis was performed by a device manufactured by Rigaku Denki Co., Ltd. The thermal analysis used a TG-DTA thermal analyzer manufactured by Rigaku Corporation.

The amount of moisture contained in the polymer was measured using a Karl Fischer moisture analyzer (trade name: CA05 model with a moisture vaporizer VA-05, manufactured by Mitsubishi Kasei Co., Ltd., detection sensitivity: 1 μg H _2). O) was used.

Effective means for imparting water insolubility in the water-soluble conductive polymers (Ia) and (IIa) having a self-doping function is to control the water content in the polymer by a drying method, a drying temperature and a processing time. Achieved by controlling. Thus, the degree of water insolubility is slightly different depending on whether the material used is in the form of a film or a powder. However, the degree of water insolubility is generally different depending on the difference in water content as summarized in Table 1.

Hereinafter, specific contents will be described in the next embodiment with reference to Table 1. However, the water-soluble self-doping conductive polymer (Ia) used here,
Alternatively, in the case of producing any of (IIa), a film was formed from an aqueous solution of about 2 wt% on an arbitrary glass substrate by spin coating. When producing a powdery product, the aqueous solution was sufficiently dried and then pulverized, or the aqueous solution was poured into a hydrophilic solvent such as methanol or acetone.

Example 1 A film or powder of the water-soluble conductive polymer (Ia) or (IIa) having a self-doping function was dried in an oven at 100 ° C. for an arbitrary time under the conditions shown in Table 1. After the treatment, the following results were obtained according to the water content.

The polymer (Ia) dried in film form in a 100 ° C. oven for 2 hours had a water content of about 1% and remained insoluble in cold water at 10 ° C. When poured into warm water, it was incompletely dissolved.

The same sample as above was dried in an oven at 100 ° C. for 10 hours.
It was not eluted on the day or even for 1 hour at 80 ° C hot water.

When the polymer (IIa) was dried in the form of a film in an oven at 100 ° C. for 10 hours, the water content was 1900 ppm, and the same level of water resistance as described above was obtained.

The polymer (Ia) in powder form and dried in an oven at 100 ° C. for 10 hours had a water content of 3800 ppm and did not dissolve even at 80 ° C. in hot water for 1 hour.

Similarly, when the polymer (IIa) was treated in the same powder form under the same conditions as above, it had a water content of 2700 ppm and the same level of water resistance as described above.

(Example 2) As in Example 1, a vacuum drying process was examined instead of oven drying. The polymer (I
When a) was dried under a vacuum environment of 100 ° C. or 120 ° C. as shown in Table 2, the following results were obtained.

100 polymer (Ia) films as samples
The treatment was carried out under the conditions of ° C. and a vacuum treatment for 1 hour. The resulting product had a water content of 1% and remained insoluble in cold water at 10 ° C, but slowly dissolved in warm water at 40 ° C.

As a result of extending the time to 5 hours under the same drying conditions as the above sample, the obtained sample had a moisture content of 1500
ppm, and slight swelling was observed in the Soxhlet extraction treatment for 1 hour.

The powdery polymer (Ia) was dried at 120 ° C. under vacuum, and as a result, had a water content of 1100 ppm and did not swell at all even after 12 hours of Soxhlet treatment, and remained insoluble.

(Example 3) As a milder drying treatment, the polymer (Ia) was put in a desiccator containing silica gel (desiccant) in the form of a film at room temperature for one month. % And partially eluted incompletely with warm water at 40 ° C. (See Table 3) In addition to the polymer (Ia), poly “thiophen-3- (2-ethanesulfonic acid)” and poly “thiophen-3- (4-butanesulfonic acid)” (Synthetic Me
tals. 1989, Vol. 30, P305, Y. IKENOUE et al.), and the same result as that of the polymer (Ia) was obtained.

Comparative Example In order to compare the effects of the present invention, a conductive polymer (Ia) or (II) having a water-soluble self-doping function was used.
When the spin-coated film of a) was manufactured and vacuum-dried at room temperature for 5 hours as shown in and in Table 3, film-like samples (each having a thickness of about 2 microns) were obtained. Was poured into water at room temperature, and completely eluted in water within 1 or 2 minutes to form a reddish brown aqueous solution.

Similarly, the same polymer (I
The powder obtained by subjecting the powder sample of a) or (IIa) to vacuum drying at room temperature for 10 hours as shown in and in Table 3 dissolved easily and quickly as in the case of the film sample described above. However, drying of the powdery sample generally took longer than that of the film-like sample, but the solubility in water was all high.

As a result of examining the water content of the conductive polymer, Table-
As shown in FIG. 3, almost 5% or more of water was contained.

<< Experimental Example 1 >> In order to examine whether or not the electrochemical activity of the water-soluble conductive polymer having a self-doping function and the water-insoluble self-doping conductive polymer had deteriorated, the behavioral change of the current-voltage curve by potential scanning was examined. investigated.

Two sample electrodes were prepared by forming a film of the water-soluble conductive polymer (Ia) having a self-doping function on an ITO (tin oxide, indium oxide transparent electrode) glass surface at room temperature under vacuum. (10 ⁻³ Torr), initial drying for 5 hours. Then, one of the sample electrodes was dried at 100 ° C. under vacuum (10 ⁻³ Torr) for 5 hours. Using these two sample electrodes separately, a conventional electrochemical cell (cell configuration: polymer (Ia) | 0.5 mol HBF ₄ (H ₂ O 6%) / acetonitrile | Pt;
(Potential scanning speed: 50, 100, 200 mV / sec), and cyclic voltammetry was measured. From the obtained results, the shoe sound before and after the drying treatment of the polymer was compared, and as shown in FIG. 1, almost no change was recognized in the oxidation and reduction processes.

However, by performing the heat treatment of Example 2, it was found that the electrochemical cycle was increased from 150 times to 6000 times or more, and the electrochemical stability was improved, and the device could be used repeatedly for a long period of time. all right.

Here, the improvement in the cycle stability was an extremely useful improvement in application as an electronic device.

<< Experimental Example 2 >> Experiments and analyzes were carried out as follows in order to examine whether or not there was any change in the chemical structure or physical structure of the polymer due to dehydration / drying treatment. In order to examine the structural change in the conductivity of the self-doped conductive polymer, the film sample of the polymer (Ia) (before treatment and at 120 ° C.)
UV-visible near-infrared absorption spectrum was measured using (× 10 hours treatment). As shown in FIG. 2, λmax of the maximum absorption wavelength corresponding to self-doping was almost the same, and undoping was not performed. It is shown that.

The thermal analysis behavior in the powder form of the polymer (Ia) was measured using TG (thermogravimeter, measurement conditions; heating rate, 10 ° C./min,
Examination with a TG range (10 mg) revealed no significant change in weight change before and after the drying treatment, as shown in FIG. The same was true for differential thermal analysis.

The change in crystallinity of the polymer by X-ray analysis was also examined. As shown in FIG. 4, no particular difference was observed before and after the drying treatment.

<< Experimental Example 3 >> In order to examine the influence on the electric conductivity before and after the dehydration and drying treatment, the powdery sample of the polymer (Ia) was examined by a conventional method using a four-terminal method. As shown in Table 2, the product subjected to drying treatment in an oven at 120 ° C. for 10 hours also showed the same electrical conductivity as a conventional conductive polymer having a water-soluble self-doping function.

Example 4 The effect of various dehydration treatments on the electrochemical responsiveness of a water-insoluble self-doping type conductive polymer was examined in detail, and as shown in FIG. An extremely fast response was stably observed. The evaluation spectroscopy cell used at this time was placed in an oven at 120
A 2-electrode incorporating a spin-coated electrode (a working electrode made of an ITO glass electrode coated with a water-resistant self-doping type conductive polymer) and a platinum mesh electrode (counter electrode) that has been dried at 10 ° C for 10 hours. Type spectroscopic cell using an acetonitrile electrolyte solution containing 0.5 mol HBF ₄ and 6% water.

Then, the spectrum change of the self-doping type conductive polymer was measured by a spectroscopic means capable of performing time-division measurement in a short time, and FIG. 5A was obtained. this house,
FIG. 5B shows the change in absorbance at a wavelength of 500 nm in the visible region. By analyzing the temporal change in the absorbance at this time, the electrochemical responsiveness of the device can be compared and examined. For example, in FIG. 5B, even when the above treatment is performed, the response of the self-doping type conductive polymer shows that the change in absorbance approaches a saturation state in about 40 ms, which is about 1 / compared to the conventional polythiophene or the like. It can be evaluated that the color change (electrochromism) is completed within 10 hours.

As described above, even when the dehydration treatment was performed, the effect of rapidly shortening the electrochemical response of the conductive polymer having the self-doping function was not impaired, but the effect of extending the life of the device was recognized.

[Effects of the Invention] Among conductive polymers, a self-doping type conductive polymer has a self-doping function through the movement of small protons, in which the doping function is easily moved, and has a high response speed of an electrochromic phenomenon, and is used as a display element. Although usefulness is anticipated, it is water-soluble, and its performance will be degraded due to humidity in the air.In addition to the use of aqueous electrolytes, non-aqueous electrolytes will be electrically conductive during repeated use. There is a disadvantage that the polymer is easily deactivated due to elution of the polymer or a change in the element surface.

However, even if it is insolubilized in cold water by a dehydration treatment, a certain degree of water resistance is imparted and it has resistance to humidity.

Furthermore, those that have become water-insoluble enough to withstand hot water extraction have resistance to humidity and moisture, despite no change in other electrical properties, and have a high humidity environment and electrolyte. It is expected that the field of use will be greatly expanded along with the high response speed, since it has become possible to use the device for a long time.

[Brief description of the drawings]

FIG. 1 shows cyclic voltammograms before and after heating and drying a film of a self-doping type conductive polymer (Ia). Cell configuration is polymer (Ia) /ITO|0.5M-HBF ₄ (H ₂ O 6%)
/ Acetonitrile | Pt., (A) in FIG.
After drying at 10 ^-3 Torr for 5 hours, FIG.
C., 10 ^-3 Torr, and heat drying for 5 hours (Example 2)
-). The potential scanning speed was 200 mV / sec for Curve 1 and for Curve 2
100 mV / sec, curve 3 is 50 mV / sec. FIG. 2 is an ultraviolet, visible, and near-infrared absorption spectrum diagram before and after the heat drying treatment of the polymer (Ia) film. FIG. 3 shows the thermal behavior of the self-doped polymer before and after the heat-drying treatment. FIG. 3 (A) shows the result when 2.3 mg of the powdery water-soluble polymer (Ia) before heating was used.
(B) was measured using 2.6 mg of a water-insoluble polymer (Ia) obtained by heating and drying the polymer. The heating rate is 10 ° C./min. FIG. 4 shows a comparison of X-ray diffraction patterns before and after the heat drying treatment. The measurement samples are both powdered polymers (Ia). FIG. 5 shows the electrochemical spectrum change of the film-form polymer (Ia) dried at 100 ° C. and 10 ⁻³ Torr for 5 hours. Cell structure polymer _{(I a) /ITO|0.5M-HBF 4 (H} 2 O6
%) / Acetonitrile | Pt. (A) of FIG. 5 shows the spectrum 1 obtained by setting the voltage to 0 V on the counter electrode basis, and the spectra 2 to 9 show the aging of the spectrum when a rectangular pulse (2.0 V) of the potential was applied from the state of the spectrum 1. Changes (every 10 ms) are tracked. Fig. 5 (B)
In the spectrum of (A), the change with time of the absorbance at a wavelength of 500 nm is tracked and normalized with respect to the reference state 1.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields surveyed (Int. Cl. ⁶ , DB name) C08G 61/00-61/12 WPI / L (QUESTEL)

Claims (3)

(57) [Claims] 1. A water-insoluble general formula (I) or (II)
A self-doping type conductive polymer having a structure represented by the formula: In the formula, Ht is NH, S, O, Se or Te, and R is a linear or branched divalent hydrocarbon group having 1 to 10 carbon atoms or a divalent hydrocarbon group containing an ether bond. And X
Is SO ₃ or CO ₂ . Z ₁ is RX-H, Z ₂ is 'a, R' RX-H, H or OR represents an alkyl group with a linear or branched having 1 to 10 carbon atoms.
The polymerization degree n is 10 or more. 2. A process for producing a water-insoluble self-doping polymer, comprising dehydrating a water-soluble self-doping conductive polymer having a structure represented by the general formula (I) or (II). . 3. A water-soluble conductive polymer having a structure represented by the general formula (I) or (II) and having a self-doping function is dehydrated to reduce the water content to less than 5%. 2) The method for producing a water-insoluble self-doping conductive polymer according to the above.