JPH01230608A - High polymer gel - Google Patents

Abstract

PURPOSE:To obtain a high polymer gel useful as a stable electrochromic material by polymerizing or crosslinking a viologen deriv. obtd. by reacting 4,4'- bipyridyl with a halogenated vinyl compd. with another polymer. CONSTITUTION:A viologen deriv. is obtd. by reacting 4,4'-bipyridyl with a halogenated vinyl compd. (e.g., vinyl chloroacetate) in a solvent (e.g., ethanol) at a molar ratio of 1:2 and thereafter washing the reaction product with a solvent which is a poor solvent for the reaction product but a good solvent for said raw materials (e.g., dimethyl ether). Then, a high polymer gel contg. a viologen deriv. unit of the formula (wherein R<1> is a group having a vinyl group unit, R<2> is a group having a vinyl group unit or having no such a group and X is a counter ion) in its molecular structure is obtd. by adding the obtd. viologen deriv., another polymer (e.g., polyacrylamide, polyacrylic acid etc.) and, if necessary, an initiator (e.g., K2S2O8) in water and polymerizing and crosslinking the mixture.

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a novel polymer gel.

[Prior Art] Viologen compounds change color (mainly from colorless to blue) upon reduction, and their application to electrochromic display elements (hereinafter referred to as EC elements) is being developed by utilizing this property. . Viologen compounds are also based on the above properties.

It is also used as an indicator for various reductions.

From the viewpoint of application to EC devices, various viologen compounds that exhibit different colors upon reduction have been synthesized and are attracting attention as display materials that can be multicolored. In addition, in order to suppress deterioration,
A dimer of viologen in which the substituents on the two nitrogen atoms of viologen are made extremely asymmetric, and the redox potential width is widened.

Viologen polymers such as trimers have also been synthesized.

[Problems to be Solved by the Invention] However, all conventional viologen compounds are used in the form of solutions. In that case, reduction occurs at the display electrode and the reduced viologen is deposited on the display electrode, but the precipitated reduced viologen diffuses into the electrolyte and disappears, resulting in poor memory performance. Also, if vibration causes flow in the electrolyte.

It tends to cause uneven coloring and lack of coloring stability.

Therefore, an object of the present invention is to provide a polymer gel containing viologen derivative units in its molecular structure, which is useful as a stable EC material.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a polymer gel containing viologen derivative units in its molecular structure.

The above-mentioned viologen derivative unit is a unit of a viologen derivative having one or more than 2g1 vinyl group moieties, and this derivative unit has the general formula (where R1 is a substituent having a vinyl group moiety.

R2 may be a unit of a viologen derivative represented by a substituent containing or not containing a vinyl group moiety, and X being a counter ion.

In the above formula (I), usually 11 and R2 each have a vinyl group moiety. Moreover, R1 and R are
Each can be a carboxylic acid vinyl ester group.

The above viologen derivative can be produced by reacting 4,4'-bipyridyl with a halogen-containing vinyl compound.

Examples of halogen-containing vinyl compounds include halogenated vinyl compounds such as vinyl halides, acrylic halides, and acryl halides; vinyl monohaloacetate, vinyl monohalopropionate, vinyl monohaloacetate, vinyl monohalocaproate, and monohalocabryl. Examples include monohalocarboxylic acid vinyl esters such as vinyl acid, vinyl monohalolaurate, vinyl monohalomyristate, vinyl monohalobalmitin, and vinyl vinyl stearate.

In producing the above viologen derivative, 4゜4゛-bipyridyl and a halogen-containing vinyl compound are reacted in a good solvent (for example, ethanol) for both at a molar ratio of 1:2, with thorough stirring. 0 The reaction temperature may be room temperature, but may be heated. 0 After completion of the reaction, it is a poor solvent for the reaction product but a good solvent for 4,4°-bipyridyl and halogen-containing vinyl compounds. Wash in excess amount of solvent (eg dimethyl ether) to obtain the product.

Since the above viologen derivative has a vinyl group moiety,
It can be polymerized or crosslinked by itself or with other polymers to form polymeric gels. Examples of such other polymers include polyacrylic acid, polymethacrylic acid, sodium polystyrene sulfonate, poly-4-vinylpyridine and its quaternized products, poly-2-acrylamide-2
- Methylpropanesulfonic acid, polyacrylamide, poly 2-hydroxyethyl methacrylate, polymethyl methacrylate, polyacrylonitrile, polymethacrylic nitrile, polyvinyl alcohol, agar, alginic acid, collagen, gelatin, gum arabic, starch, etc.

The polymer gel of the present invention can be produced by polymerizing monomers constituting these polymers in water in the presence of the viologen derivative.

To illustrate the method for producing the polymer gel of the present invention, the above monomer, viologen derivative, and initiator (for example, potassium persulfate, etc.) are added to water at 30°C to 80°C.
The polymerization is carried out at a temperature of 4°C to 70°C, preferably 4°C to 70°C. In this case, ferrous chloride is allowed to coexist with the initiator,
Coalescence can also be carried out at a low temperature such as 0° C. by a so-called redox polymerization method. Furthermore, instead of using an initiator, polymerization can also be initiated by irradiation with radiation, electron beams, etc. To increase the hardness of the gel,
Other crosslinking agents (for example, N, N-methylenebisacrylamide, ethylene glycol dimethacrylate, etc.) may be added. The proportion of viologen derivative units in the polymer constituting the obtained polymer gel is usually 0. .001
It is mol% or more. Incidentally, using the viologen derivative obtained in Example 1 (A) below as the viologen derivative,
When acrylic acid is polymerized in the presence of N,N-methylenebisacrylamide, a polymer gel having a structure represented by formula 1 is obtained.

In addition, in order to increase the conductivity in the polymer gel, a supporting electrolyte may be added. Preferred supporting electrolytes include:
Potassium chloride, potassium bromide, sodium sulfate, sodium hydroxide, sulfuric acid, etc.

[Example] Example 1 (A) 4.4'-Dipyridyl and monochlorovinyl acetate were added at a molar ratio of 12 to ethanol in an amount 0.5 times the volume of monochlorovinyl acetate, and the mixture was stirred well at room temperature. The reaction was allowed to proceed for 72 hours. The reaction product was washed with excess dimethyl ether, filtered through filter paper, and then dried. This was subjected to liquid chromatography, desired fractions were collected, and a desired viologen derivative represented by the following general formula was obtained. This viologen derivative was highly water-absorbing.

CH2=CH The infrared absorption spectrum of this viologen derivative is shown in FIG. 1, and the results of its elemental analysis were as follows.

C: 54.35 (calculated value 54.44) N: 7
．． 12 (calculated value 7.05) This viologen derivative showed an electrochromic effect and turned blue upon reduction. When the solvent was water, the ultraviolet absorption spectrum during coloring was as shown in FIG.

(B) Purified acrylamide and water at a weight ratio of 2
The viologen derivative obtained in Example 1 (A) was added thereto at a ratio of 0.02M, and potassium persulfate was further added as an initiator at a ratio of 1.18 mol % of acrylamide. Stir this mixture well and after freezing and degassing,
Polymerization was performed to obtain a polymer gel. This gel was filled between a pair of tin oxide transparent electrodes to produce a cell with a thickness of 1.2 mm. When a DC voltage of 3°5V was applied to this cell, it colored blue. Even when this cell was subjected to vibration, no color unevenness was observed. The coloring characteristics at this time are shown in Figure 3 (curve b).
It should be noted that 0 of the viologen derivative obtained in Example 1 (A)
．． The coloring characteristics when using the 02M aqueous solution were as shown in curve a in FIG.

Example 2 Purified acrylamide and wood were mixed at a weight ratio of 2:8, and the viologen derivative obtained in Example 1 (A) was added to the mixture at a weight ratio of 2:8.
．． In addition, potassium persulfate was added as an initiator at a ratio of 1.18 mol % of acrylamide, and potassium chloride was added as a supporting electrolyte at a ratio of 0.03M. This mixture was thoroughly stirred, frozen and degassed, and then subjected to one polymerization to obtain a polymer gel. This gel was filled between a pair of tin oxide transparent electrodes to produce a cell with a thickness of 1.2 mm.

When a DC voltage of 3.5 V was applied to this cell, it colored blue. The coloring rate at that time was increased by about 4% compared to the one to which no supporting electrolyte was added. Further, even when vibration was applied during coloring, no color unevenness was observed.

Example 3 Purified acrylamide and water were mixed at a weight ratio of 1:9, and the viologen derivative obtained in Example 1(A) was added to the mixture at a weight ratio of 1:9.
In addition, N,N-methylenebisacrylamide was added as a crosslinking agent in a proportion of 1 mol % of the acrylamide, and potassium persulfate was added as an initiator in a proportion of 1 mol % of the acrylamide. This mixture was thoroughly stirred, frozen and degassed, and then polymerized to obtain a polymer gel.

This gel becomes harder than when no cross-linking agent is added;
Increased strength against pressure. This gel was filled between a pair of tin oxide transparent electrodes to produce a cell with a thickness of 1.2 mm. When a DC voltage of 3.5 V was applied to this cell, it colored blue.

[Effects of the Invention] As explained above, according to the present invention, a polymer gel useful as an EC material exhibiting stable coloring properties is provided.

[Brief explanation of the drawing]

Figure 1 is an infrared absorption spectrum diagram of a viologen derivative;
FIG. 2 is a graph showing the ultraviolet absorption spectrum of the reduced viologen, and FIG. 3 is a graph showing the coloring characteristics of the polymer gel. 1 is a turtle (cm”) Figure 1 Figure 2

Claims (4)

[Claims] (1) A polymer gel containing viologen derivative units in its molecular structure. (2) The viologen derivative unit has a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (I) (Here, R^1 is a substituent having a vinyl group moiety, R^
2. The polymer gel according to claim 1, wherein 2 is a viologen derivative represented by a substituent containing or not containing a vinyl group moiety, and X is a counter ion. (3) The polymer gel according to claim 2, wherein R^1 and R^2 each have a vinyl group moiety. (4) The polymer gel according to claim 2, wherein R^1 and R^2 are each a carboxylic acid vinyl ester group.