JPH01225915A - Fixed film - Google Patents

Abstract

PURPOSE:To improve the characteristics of a composite film composed of a functional low polymer such as liquid crystal and dye and high polymer by providing a composite high-polymer film having independent or continuous dispersed phases in the high polymer and electrodes provided to sandwich the composite high-polymer film. CONSTITUTION:This film is constituted by having the composite high-polymer film formed by dispersing the liquid crystal, dye, etc., into the porous high polymer and the electrodes provided to sandwich the composite high-polymer film. The dispersed phases are obtd. by uniformly dispersing the liquid crystal or the dye alone or the mixture composed of the liquid crystal and the dye into the high-polymer matrix and are different from the homogeneous dispersion obtd. by the conventional known casting method. The composite high-polymer film is obtd. by evaporating the solvent from a high-polymer soln. contg., for example, water and alcohol to obtain the porous high-polymer film, packing the functional low polymer such as liquid crystal and dye into the pores of the porous high-polymer film to obtain the composite film and providing the electrodes thereto via the composite film. The properties combining the function possessed by the high polymer and the function possessed by the low polymer are thereby obtd. from one stock.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fixed membrane in which an electrode is attached to a polymer composite membrane containing a functional low molecule.

(Conventional technology) Today, liquid crystals are used in a wide variety of fields.

Liquid crystals are characterized by their optical anisotropy and the fact that their molecular arrangement can be easily changed by external fields such as electric and magnetic fields. In particular, in ferroelectric liquid crystals, the driving force is the torque generated by the interaction between spontaneous polarization and an electric field, and this driving force is so large that it is attracting attention as a material for high-speed display elements. Furthermore, some dyes have excellent optical properties, such as electro-optic effects caused by ordinary electric fields or optical electric fields, and nonlinear optical effects. These functional low-molecular liquid crystals and dyes have the possibility of various molecular designs and various optical properties, but they have fluidity and have problems in fixing their structures.

In conventional optical display elements, functional low molecules such as liquid crystal are sandwiched between two glass plates to fix the functional low molecules. However, if a glass plate is used, problems will arise in terms of flexibility, weight reduction, and wide area. For this reason, methods of fixing functional polymers using polymers that are generally flexible, lightweight, and easy to expand over a wide area have been considered. Among polymers, ferroelectric polymers have high dielectric constant, fast switching, piezoelectricity, pyroelectricity,
It has excellent electrical properties such as electrostriction. Therefore, liquid crystals obtained by combining low-molecular substances and polymers, both of which have functionality, and/or composite films of dyes and polymers have various functions in addition to the electro-optic effects and nonlinear optical effects of the starting materials. It is expected to be used as a promising industrial material for a wide variety of applications, including optical elements such as switches and memories, devices for second harmonic generation (in semiconductor lasers), optical bistable memories, and optical processing. Conventionally known methods for obtaining a composite film of liquid crystal and polymer include the following two methods.

(1) A method of forming a film by casting from a mixed solution of a liquid crystal and a polymer by a conventional method (solvent evaporation method), that is, a polymer such as polyvinyl chloride or polycarbonate and N-(4-ethoxybenzylidene)-4' -butylaniline, butyl-4
- A method in which a liquid crystal such as (4-ethoxyphenoxycarbonyl) phenyl carbonate is dissolved in a common solvent, the mixed solution is uniformly cast in a petri dish, and the solvent is evaporated to form a film, (2) water surface development method That is, a liquid crystal and polymer mixed solution is dropped onto the water surface through the tank wall, and several tens of composite ultra-thin films obtained by self-diffusion are laminated to form a film.

However, the properties of composite films of functional low molecules such as liquid crystal dyes and polymers prepared in this manner were not necessarily satisfactory.

(Means for Solving the Problems) The problems faced by the prior art as described above are that polymer composite films formed by dispersing liquid crystals, dyes, etc. in porous polymers;
This problem is solved by a fixed membrane comprising electrodes sandwiching this polymer composite membrane.

The dispersed phase in the present invention is one in which a liquid crystal or a dye alone or a mixture of a liquid crystal and a dye is uniformly dispersed in a polymer matrix, which is different from a non-uniform dispersion obtained by a conventional well-known casting method.

The polymer composite membrane used in the present invention is produced by the following method, for example. In this method, a porous polymer membrane is obtained by evaporating the solvent from a polymer solution containing water and alcohol, and the pores of this porous polymer membrane are filled with functional low molecules such as liquid crystals and dyes. A membrane is obtained, an electrode is provided through the composite membrane, and a fixed membrane is obtained.

(Function) Ethyl alcoholic water forms a cyclic cluster of three molecules due to hydrogen bonds between ethyl alcohol molecules, and these three clusters further associate to form a package containing one hydronium ion. It forms a junction compound,
This clathrate has hydrogen bonds with water molecules. Therefore, when a certain amount of alcohol water is dispersed in a solution of a polymer dissolved in a good solvent, the alcohol water in the solution becomes uniform spherical particles due to interfacial tension as the solvent evaporates, and after the solvent evaporates, a porous structure is formed. Form. It has been found that by dry heat drying at 100° C. or higher, a porous membrane with spherical pores in which alcoholic water has completely evaporated can be obtained. Furthermore, since ethyl alcohol has hydrophilic properties, if a certain amount of alcohol is uniformly diffused into a solution of a polymer dissolved in a good solvent, and then the solvent is evaporated in a humid environment, a porous film will also form. I can be hatched. If the polymer composite membrane of the present invention is formed at a temperature slightly higher than room temperature, the dispersed phases will have a structure in which the mutually dispersed phases are connected by narrow channels due to shrinkage during film formation. Furthermore, when the film is formed at a temperature lower than room temperature, each pore takes on a completely independent dispersed structure.

Further, the present invention will be explained in detail.

In the present invention, (1) after dissolving the polymer in its good solvent, adding a certain amount of alcohol and water, mixing thoroughly, casting in a flat petri dish, and evaporating the solvent to obtain a porous membrane (2) ), In method (1), after adding a certain amount of alcohol and thoroughly mixing it, it is cast into a flat petri dish, and the solvent is evaporated in a container (desiccator, chromatography tank, etc.) whose humidity has been adjusted in advance to form a porous membrane. I get it. Liquid crystal (and or dye) is added to the porous membrane obtained above in a vacuum dryer.
After filling, electrodes can be attached and used as a sample.

As the polymer that can be used in the present invention, any polymer can be used as long as it can form a liquid crystal (and/or dye)/polymer fixed film. Polyethylene as a polymer,
Vinyl compounds and addition polymers of vinyl compounds such as polyacrylic acid, polymethyl acrylate, polyvinyl acetate, polyacrylonitrile, polyvinyl chloride, polyvinyl fluoride, methacrylic acid such as polymethacrylic acid, polymethyl methacrylate, polyethyl methacrylate, etc. Ester, polyvinylidene chloride, polyvinylidene fluoride, vinylidene cyanide, vinylidene fluoride/trifluoroethylene copolymer,
vinylidene fluoride/tetrafluoroethylene copolymer,
Copolymers of vinyl compounds or fluorine compounds such as vinylidene cyanide/vinyl acetate copolymers; compounds containing fluorine such as polytrifluoroethylene, polytetrafluoroethylene, and polyhexafluoropropylene; polyamides such as nylon 6 and nylon 66; polyimide, polyurethane,
Examples include polypeptides, polyesters such as polyethylene terephthalate, and polyethers such as polycarbonate, polyoxymethylene, polyethylene oxide, and polypropylene oxide. Although commercially available polymers can be used alone, they can also be used as a mixed system in which various types of polymers are combined. In this case, the polymers have good compatibility with each other, which not only provides excellent film forming properties but also improves the properties of the resulting fixed film, such as chemical stability, weather resistance, impact resistance (thermal,
It is desirable to use them in combination, taking into consideration the purpose of use (mechanical), etc.

In addition, good solvents are required to dissolve polymers (depending on the polymer. For example, polyvinyl chloride uses tetrahydrofuran, cyclohexanone, methyl ethyl ketone, dimethyl formamide, etc.; polyvinyl acetate uses chloroform,
Methanol, acetone, butyl acetate, etc., polyacrylic esters and polymethacrylic esters include acetone, ethyl acetate, tetrahydrofuran, toluene, etc., polyacrylonitrile includes dimethylformamide, etc., polyethylene oxide includes benzene, dimethylformamide, etc., vinylidene fluoride, Vinylidene cyanide and its copolymers include ketones such as acetone, methyl ethyl ketone and cyclohexanone, esters such as methyl acetate and methyl acrylate,
Examples include cyclic ethers such as ethylene oxide, propylene oxide, tetrahydrofuran and dioxane, amines such as n-butylamine, and amides such as dimethylformamide and dimethylacetamide. Further, the amount of the above-mentioned solvent to be added may be any amount based on the polymer, but in consideration of film forming properties, a 20-0.5% solution is preferable.

As the liquid crystal that can be used in the present invention, any liquid crystal that can form a liquid crystal/polymer fixed film can be used. Examples include p-azoxyanisole, cholesteryl nonanoate, 4-methoxybenzylidene-4'-n-butylaniline, 4-methoxy-4'-butylazoxy-
Nematic liquid crystals such as benzene, 4,4'-dimethoxyazobenzene, p-azoxyanisole, 4-cyano-4'-n-pentylbiphenyl, p-2methoxybutyl-p'-cyanobiphenyl, terephthal-bis-butylaniline, N-(4-cyanobenzylidene), i/,
-Octyloxyaniline, dodecyloxyazobenzene, ethyl p-(p'-phenylbenzalamino)benzoate, 4-hebutyloxybenzylidene-4'-pentylaniline, 4-butyloxybenzal-4-ethylaniline, 4 - (4'-phenylbenzylidene amino)
-n-butylcinname), 4-(4'-decyloxybenzylideneamino)2-methylethylkenname'-)
, 4 (n-hexyloxy)phenyloxy-4'
-(2-methylbutyl)biphenyl-4'-carboxylate, smectic liquid crystals such as ZLI-3489, cholesteryl nonanoate, (-)-2-methyl-p-(p'-
Examples include cholesteric liquid crystals such as methoxybenzylidene amino) cinnamic acid, cholesteryl myristate, cholesterol halides and esters, and discotic liquid crystals such as hexabutoxytriphenylene. In this case, the above-mentioned liquid crystals can be used alone, but a plurality of them can also be used in combination for the purpose of improving the performance of the base liquid crystal, such as phase transition temperature, temperature range, chemical stability, film formability, etc.

The dyes (pigments) that can be used in the present invention include nonlinear dyes such as azo, anthraquinone, tetrazine, and coumarin dichroic dyes, which are conventionally mixed with liquid crystals and used for the light absorption anisotropy of dyes. 4-demethylamine-4'-nitrostilbene, o-(m-p-)nitroaniline, 2-methyl-4-nitroaniline, merocyanine, etc., and bis(1-thio-2-ferulate) with optical properties Nickel-tetrabutylammonium, bis(1-thio-
Examples include near-infrared absorbing dyes such as nickel (2-naphtholate)-tetrabutylammonium and bis(1,2,3,4-tetrachloro-5,6-sithioferto)nickel(n)tetra-n-butylammonium. .

The alcohol used in the present invention is methanol,
Lower-hydric alcohols such as ethanol are preferred. The amount of the alcohol added may be arbitrary, but it is preferably 5-30% based on the common solvent as long as the polymer does not precipitate. Also, benzene, if desired, in addition to alcohol.
Auxiliary additive components such as hydrocarbons such as toluene, xylene, etc. can also be added.

The water used in the present invention is preferably pure water. In the above, the amount of water added to the alcohol may be any amount as long as the polymer does not precipitate, but it is preferably 5 to 50% to the alcohol. Alternatively, if a porous polymer film is obtained by uniformly dispersing a certain amount of alcohol in a solution of a polymer dissolved in a good solvent and then evaporating the solvent in a humid environment, the relative humidity of the environment is It varies depending on the type of solvent, but 60-100%, preferably 75-95%.
%.

The porous polymer membrane obtained by the present invention has a uniform pore diameter and distribution state because the alcoholic water exists uniformly as minute droplets in the film-forming special polymer solution. It is. Furthermore, since the dispersed phase is formed from alcohol, film formation is not inhibited and mechanical strength and dimensional stability are greatly improved. Such characteristics are important in utilizing the present porous fixed membrane as an industrial material.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

Example 1゜Hinylidene fluoride-trifluoroethylene copolymer7.
After dissolving 5 parts in 100 parts of tetrahydrofuran solvent,
Add 10 parts of ethyl alcohol and 3 parts of pure water, mix well, cast onto a flat Petri dish, form a film by solvent evaporation method, and heat-treat at 100°C for 6 hours in a vacuum dryer.
A cast membrane was obtained in which the pores had a diameter of about 8 μm and the pores were connected by thin channels to form a continuous phase. 9 on this membrane
Liquid crystal, ZL I-3489, 2, in a vacuum dryer at 0°C.
A fixed membrane was obtained by impregnating and filling 5 parts, and an electrode was attached to prepare a specimen. FIG. 1 shows the DE hysteresis curve of the obtained fixed membrane specimen. For comparison, vinylidene fluoride-trifluoroethylene copolymer and liquid crystal (ZLI-3489
) are shown in FIGS. 2 and 3, respectively. Also, 7.5 parts of vinylidene fluoride-trifluoroethylene copolymer and 5 parts of ZLI-34892 were dissolved in a common solvent, tetrahydrofuran 100B, and the above-mentioned conventional method was used. Figure 4 shows the results of the cast composite membrane. As can be seen from Figures 1, 2, and 3, the hysteresis curve of the fixed film on which ZLI-3489 is immobilized is a typical rectangular hysteresis curve for vinylidene fluoride-trifluoroethylene copolymer, liquid crystal, and ZLI-3489. Although it does not give a perfect hysteresis curve, it is clear that polarization reversal has occurred. Since the vinylidene fluoride-trifluoroethylene copolymer only exhibits nearly linear behavior when the electric field amplitude is about 4 MV/m, the hysteresis curve of this ZLI-3489 fixed membrane is due to the polarization reversal in the direction of ZLI-3489. Due to Z
This is because LI-3489 exhibits ferroelectric properties. That is, vinylidene fluoride-trifluoroethylene copolymer serves as the fixed film of ZLI-3489. On the other hand, as can be seen from the fact that the composite film obtained by the conventional method shows almost linear behavior at an electric field amplitude of about 4 MV/m, ZL
There is no significant fixed effect of I-3489.

Example 2゜Hnylidene fluoride-tetrafluoroethylene copolymer [
Vinylidene fluoride 80%, manufactured by Daikin Industries, Ltd.]7.
After dissolving 5 parts in 100 parts of tetrahydrofuran solvent,
After mixing 10 parts of ethyl alcohol, the mixture was cast into a flat petri dish and the solvent was evaporated in a chromatography tank with a relative humidity of 80% to form a film. Thereafter, heat treatment was performed at 100° C. for 8 hours in a vacuum dryer to obtain a cast film. The SEM image of this membrane revealed that the obtained membrane was a porous membrane with a pore size of 4-5 μm. This porous membrane was heated at 100°C in a vacuum dryer to obtain liquid crystal, 4-(4'-n-decyl, ruoxybenzylideneamino)2-methylbutylcinnamate (
After impregnating and filling 2.5 parts of DOBAMBC), an electrode was attached to prepare a specimen. DE hysteresis curves of the specimens were obtained and compared with those of vinylidene fluoride-tetrafluoroethylene copolymer and DOBAMBC used as starting materials. The hysteresis curve of a liquid crystal fixing film obtained by impregnating and filling a vinylidene fluoride-tetrafluoroethylene copolymer porous film with DOBAMBC shows a hysteresis curve similar to that of Example 1, indicating that polarization reversal has occurred. On the other hand, for comparison, the hysteresis curve of a composite film obtained by casting DOBAMBC and vinylidene heptafluoride-tetrafluoroethylene copolymer by a conventional method using tetrahydrofuran as a common solvent showed nearly linear behavior.
There is not much fixed effect of DOBAMBC.

Example 3 A mixture of 7 parts of polyvinylidene fluoride (manufactured by Okowari Kagaku Kogyo Co., Ltd.) and 3 parts of methyl methacrylate was dissolved in 100 parts of methyl ethyl ketone solvent, and then 20 parts of methyl alcohol,
Pure water 3B was added, the mixture was cast into a flat Petri dish, and the solvent was slowly evaporated to obtain a cast film. From the SEM image of the membrane,
It was found that the obtained membrane was a porous membrane with a pore diameter of approximately 5 μm, and the pores were connected by thin channels to form a continuous phase. The liquid crystal ZLI-3 was added to this film in a vacuum drying oven at 80°C.
489 (manufactured by Merck & Co., Ltd.) was impregnated and filled to obtain a composite membrane. When this composite membrane was heated again to 120°C, ZLI-34
89 oozed out onto the membrane surface.

This is because ZLI-3489 oozes out as a continuous phase domain through the continuous pores formed by the matrix made of polyvinylidene fluoride and methyl methacrylate, and is in good agreement with the results of the SEM image. This phenomenon is observed above the transition point of ZLI-3489 from the cholesteric phase to the isotropic phase of 87°C.

Example 4゜In Example 1, liquid crystal, 0 instead of ZLI-3489
-0.5g of nitroaniline to 0.5g of ethyl alcohol
A composite film was obtained in which the liquid crystal/dye mixture was dispersed in the polymer as fine spherules by the same process as in Example 1 except that a mixture of ZLI-34892 and 0 g dissolved in cc was used. The obtained composite membrane exhibits a hysteresis curve;
Polarization reversal is occurring. In other words, polymers are liquid crystals/
It serves as a dye fixing film. ZLI-348 for comparison
A composite membrane obtained by a conventional method using 9 and O-nitroaniline as methyl ethyl ketone lt-solvent did not exhibit a remarkable hysteresis curve as in the case of a porous membrane impregnated and filled with a liquid crystal/dye mixture.

As explained in detail above, the polymer membrane obtained by the present invention is a porous polymer membrane in which spherical pores are uniformly dispersed in an independent or partially continuous structure, and low-molecular substances such as liquid crystals and dyes are applied to the membrane. The impregnated and filled low-molecular composite membrane has properties that combine the functions of polymers and low molecules in a single material.

[Brief explanation of the drawing]

Figure 1 shows the D of the fixed membrane of the present invention obtained in Example 1.
-E is a diagram showing a hysteresis curve. FIG. 2 is a diagram showing the DE hysteresis curve of the vinylidene fluoride-trifluoroethylene copolymer used as the starting material for the fixed membrane of the present invention in Example 1. FIG. 3 is a diagram showing the DE hysteresis curve of ZLI-3489, a liquid crystal used as a starting material for the fixed membrane of the present invention in Example 1. FIG. 4 is a diagram showing the D-E hysteresis curve of the composite membrane obtained by a conventional method in Example 1. Figure 1 Composite membrane E (MV/m) Figure 2 E (MV/m) Third factor E (MV/m)

Claims (5)

[Claims] (1) A fixed membrane comprising a polymer composite membrane having an independent or continuous dispersed phase in the polymer, and electrodes provided on both sides of the polymer composite membrane. (2) The fixed film according to claim 1, wherein the dispersed phase is a liquid crystal. (3) The fixed membrane according to claim (1), wherein the dispersed phase is a dye. (4) The fixed film according to claim 1, wherein the dispersed phase is a mixture of liquid crystal and dye. (5) The polymer composite membrane is formed by filling the pores of a porous polymer membrane formed by evaporating a solvent from a polymer solution containing water and alcohol with a substance. The fixed membrane according to claim (1).