JPH10319451A - Organic nonlinear optical material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an org. nonlinear optical material which has excellent third order nonlinear optical characteristics such as generation of phase conjugate waves and optically bistable phenomenon, which can be formed into a thin film by an easy method such as spin coating, dip coating and bar coating, and which has high resistance against laser light, by using a water-soluble π-electron conjugate polymer. SOLUTION: A water-soluble π-electron conjugate polymer is used. The water- soluble π-conjugate polymer is produced by introducing substituents such as sulfone groups, carboxyl groups and amino groups into a π-electron conjugate polymer having alternately connected single bonds and double bonds so as to make the polymer into water-soluble. As for the water-soluble π-electron conjugate polymer, for example, a water-soluble polyaniline, water-soluble polypyrrole, water-soluble polythiophene, water-soluble polyparaphenylene and water-soluble polyparaphenylenevinylene can be used, and a water-soluble polyaniline is preferably used because it has high stability in air. A water-soluble polymer means that the polymer has >=0.1 wt.% solubility with water at 25 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has excellent third-order nonlinear optical characteristics characterized by phase conjugate wave generation and optical bistability, and forms a thin film by a simple method such as spin coating, dip coating and bar coating. The present invention relates to an organic nonlinear optical material having high laser light resistance.

[0002]

2. Description of the Related Art In recent years, nonlinear optical materials have been considered for use as optical devices such as ultrahigh-speed optical switches, optical bistable elements, phase correction elements, and wavelength conversion elements. Up to now, higher performance, that is, (1) a large nonlinear susceptibility has been obtained by using metal fine particles such as gold and silver, semiconductor fine particles such as CdS and V ₂ O ₅ , and organic compounds.
Nonlinear optical materials that satisfy (2) high transparency (low absorption) in the operating wavelength region and (3) high response speed have been developed.

[0003] Among them, it has been reported that some conjugated polymers exhibit a third-order nonlinear optical effect derived from their π-electron conjugated system. For example, Phys. Rev. Lett.,
vol. 36, p. 956 (1976), the polydiacetylenebis (paratoluenesulfonate) (PTS) THG (3
Third-order nonlinear optical constant obtained by measurement of higher harmonics) χ ⁽³⁾
Has been reported to show a considerably large value of χ ⁽³⁾ = 1.6 × 10 ^-10 esu, but it is said that it is difficult to form a thin film which is indispensable for device fabrication because it is insoluble and infusible. There's a problem.

[0004] As an attempt to improve the molding processability, a soluble precursor aqueous solution is spin-coated to form a thin film, and then a conjugated polymer such as polyparaphenylenevinylene (PPV) or polythienylene is heated. A method for obtaining a thin film of vinylene (PThV) to form a non-linear optical thin film is disclosed in Japanese Patent Application Laid-Open Nos. Hei.
-289922. Χ ⁽³⁾ by THG measurement is χ ⁽³⁾ = 5 to 8 × 10 ⁻¹² esu (PP
V) and χ ⁽³⁾ = 3 × 10 ⁻¹¹ esu (PThV). Even the method using a soluble precursor as described above has a problem that a high-temperature heat treatment is finally required.

According to Appl. Phys. Lett., Vol. 48, p. 1187 (1986), polybenzothiazole (PBT) is DFWM (degenerate four-wave mixing). The measurement indicates that χ ⁽³⁾ = 9 × 10 ⁻¹² . The problem is that this value is about two orders of magnitude smaller than PTS. According to Synth. Met., Vol. 49-50, p. 13 (1992), emeraldine base polyaniline shows a relatively large value of χ ⁽³⁾ = 8 × 10 ^-10 in DFWN measurement, It is soluble only in N-methylpyrrolidone (NMP) which is a boiling point solvent, and there is a problem in handling.

Further, many organic nonlinear optical materials reported so far are decomposed by irradiation with laser light, and their stability is a problem.

[0007]

An object of the present invention is to provide an organic nonlinear optical material using a water-soluble π-electron conjugated polymer in view of the above problems.

Another object of the present invention is to form a thin film by a simple method such as spin coating, dip coating and bar coating, which is excellent in third-order nonlinear optical characteristics characterized by phase conjugate wave generation and optical bistability. And to provide an organic nonlinear optical material having high laser light resistance.

[0009]

The above objects are achieved by the following (1) to (3).

(1) An organic nonlinear optical material using a water-soluble π-electron conjugated polymer.

(2) An organic nonlinear optical material, wherein the water-soluble π-electron conjugated polymer according to (1) is a water-soluble polyaniline.

(3) An organic nonlinear optical material using a mixture of the water-soluble π-electron conjugated polymer described in (1) and a water-soluble or water-dispersible polymer.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The water-soluble π-electron conjugated polymer used in the organic nonlinear optical material of the present invention is a π-electron conjugate having a continuation of a single bond and a double bond alternately.
The compound is made water-soluble by introducing a substituent such as a carboxyl group and an amino group.

Examples of the water-soluble π-electron conjugated polymer include water-soluble polyaniline, water-soluble polypyrrole, water-soluble polythiophene, water-soluble polyparaphenylene, water-soluble polyparaphenylenevinylene, and the like. A water-soluble polyaniline having high stability in the above is preferably used.

The term "water-soluble" as used herein refers to a case where the solubility in water at 25 ° C. is 0.1% by weight or more.

The water-soluble polyaniline used in the organic nonlinear optical material of the present invention, which is one of the water-soluble π-electron conjugates, has an average of 0.1 to 4 aromatic rings in the polyaniline skeleton per aromatic ring. Of SO ₃ M and 0-3 on average.
It is substituted with 9 Rs (provided that the sum of SO ₃ M and R is 4).

Here, M in SO ₃ M is selected from the group consisting of a hydrogen atom, an alkali metal (eg, sodium, potassium, rubidium, etc.), an alkaline earth metal (eg, calcium, magnesium, etc.) and an ammonium group. And preferably a hydrogen atom.

R is a hydrogen atom, a halogen atom, preferably a chlorine atom, a fluorine atom and a bromine atom, an alkyl group having 1 to 20 carbon atoms, preferably 1 to 8 carbon atoms, and 1 to 20 carbon atoms, preferably An alkoxy group having 1 to 8, an alkylthio group having 1 to 20, preferably 1 to 8 carbon atoms,
The alkylamino group, carboxyl group, or ester residue having 1 to 20, preferably 1 to 8 carbon atoms has 1 carbon atom.
And at least one selected from the group consisting of carboxylic acid ester groups, nitro groups and cyano groups of from 1 to 20, preferably 1 to 8. Of these, electron-donating groups such as a hydrogen atom, an alkyl group, an alkoxy group, an alkylthio group, and an alkylamino group are preferred.

Further, SO ₃ M is preferably 0.5 to 1.5 on average, and R is preferably 2.5 to 3.5 on average. However, the sum of SO ₃ M and R is 4.

The water-soluble polyaniline used in the organic nonlinear optical material of the present invention can be represented by the following general formula (1).

[0021]

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Wherein M and R are as described above, p is 0.1 to 4, and q is 0 to 3.9 (provided that
p + q = 4), X is an anion of a protonic acid as a dopant, and n is a valency of the anion, usually 1 to
Trivalent, preferably 1-2. And / or formula (2) and / or formula (3)

[0023]

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[0024]

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It has a repeating unit represented by the formula or other repeating units.

The anions of the protonic acid include chloride, bromide, iodide, nitrate, sulfate, phosphate, borofluoride, perchlorate, thiocyanate, acetate, and propionate. There are 1 to 3 valent anions such as an ion, p-toluenesulfonic acid ion, trifluoroacetate ion and trifluoromethanesulfonic acid ion, and preferably 1 to 2 valent anions. Further, the sulfonic acid ion introduced into the aromatic ring of the polyaniline can be used as the anion of the protonic acid.

The water-soluble polyaniline used in the present invention is produced, for example, as follows. First, polyaniline is stirred and dispersed in an organic solvent, and chlorosulfuric acid is added thereto while heating to form chlorosulfurized aromatic rings in the polyaniline skeleton.The resulting chlorosulfonylpolyaniline is hydrolyzed in water to obtain a water-soluble polymer. A sulphonated polyaniline is obtained.

The sulfonation rate of the sulfonated polyaniline can be freely adjusted. The sulfone group has an effect of weakening the conjugation of the polyaniline main chain because it has an electron-withdrawing property and causes steric hindrance. Therefore, the degree of conjugation can be adjusted by the sulfonation rate, and adjustment can be made to maximize the nonlinear optical effect. Further, since the pH of the aqueous solution of the sulfonated polyaniline can be adjusted to any pH, the doping rate and thus the electric conductivity can be freely adjusted. Therefore, adjustment that maximizes the nonlinear optical effect is possible.

In order to apply the organic nonlinear optical material of the present invention to a substrate, methods such as spin coating, bar coating, gravure coating, kiss coating, blade coating, roll coating, and dip coating can be used.

Since the water-soluble π-electron conjugate used in the organic nonlinear optical material of the present invention exhibits high solubility in water, it can be directly applied to a substrate from a single aqueous solution. In order to improve properties, coatability, adhesion to the substrate, strength of the coating film, water resistance, etc., if necessary,
It can also be used by blending with a water-soluble polymer or an aqueous polymer emulsion (water-dispersible polymer). Examples of such water-soluble polymers include polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol, polyacrylamide, sodium polyacrylate, polyacrylic acid, poly-2-acrylamido-2-methylpropanesulfonic acid, and sodium polystyrenesulfonate. ,
Examples include homopolymers such as polystyrenesulfonic acid, polyvinylsulfonic acid, polyallylamine, and polyethyleneimine, and copolymers containing these components. Examples of the aqueous polymer emulsion (water-dispersible polymer) include acrylic acid, methacrylic acid, methyl acrylate, methyl methacrylate, ethyl acrylate,
Ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate,
Acrylic emulsions obtained by (co) polymerizing hexyl acrylate, hexyl methacrylate, octyl acrylate, octyl methacrylate, hydroxyl acrylate, hydroxyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, and the like are included.

For example, in the case of using a sulfonated polyaniline, in order to improve the transparency of the coating film at the operating wavelength, the compatibility when blended with polyacrylic acid or an acrylic emulsion among the above blended polymers is high. Can be preferably used.

The mixing ratio of the sulfonated polyaniline to the polyacrylic acid or acrylic emulsion is 0.01 to 0.01 in terms of the ratio of the sulfonated polyaniline to the total solid content.
0.95 is good, and preferably 0.5 to 0.8.

Further, as the water-dispersible polymer, a sol dispersed in an aqueous solvent can be used. The sol is obtained by hydrolyzing a metal compound in a solvent. The metal compound can be selected from metal alkoxides, acetates, oxalates, nitrates, chlorides and the like. Among these, metal alkoxides are particularly preferred.

Representative metal alkoxides include silicon alkoxides such as tetramethoxysilane and tetraethoxysilane, and titanium alkoxides such as aluminum (III) n-butoxide.

The solvent for hydrolyzing the metal compound is not particularly limited as long as it can uniformly dissolve the metal compound. Further, the solvent may contain a stabilizer such as glycerol or triethylene glycol, an organic acid, a mineral acid, or the like, if necessary.

For example, the mixing ratio of the sulfonated polyaniline to the sol (water-dispersible polymer) is preferably 0.01 to 0.95, more preferably 0.1 to 0.9, based on the total weight of the sulfonated polyaniline. 5-0.9 is good.

[0037]

The present invention will be described more specifically with reference to the following examples.

(Synthesis of Sulfonated Polyaniline) Synthesis Example 1 Aniline 2 was added to 300 ml of 1.2 mol / l hydrochloric acid aqueous solution.
8 g was added dropwise with stirring. This was cooled to 0 ° C. 3
0 g of ammonium persulfate was dissolved in 60 ml of ion-exchanged water, and added dropwise to the above solution over 30 minutes. After completion of the dropwise addition, the mixture was further stirred at 0 ° C. for 5 hours. The deposited green precipitate was filtered and washed with ion-exchanged water until the color of the filtrate disappeared. Further, the filtrate was washed with methanol until the color of the filtrate disappeared. 9 g of the obtained polyaniline was dispersed in 270 ml of 1,2-dichloroethane and heated to 85 ° C.
21.8 g (about 2 times mol) of chlorosulfuric acid was dissolved in 15 ml of 1,2-dichloroethane and added dropwise. After the dropwise addition, the mixture was heated and stirred at 85 ° C. for another 5 hours. After cooling to room temperature, the reaction product was filtered out and washed with chloroform. After air drying, disperse in 400 ml
Heated to reflux for an hour. The resulting green solution was filtered to remove insolubles, the filtrate was concentrated with a rotary evaporator, and acetone was added to precipitate a green precipitate. The deposited precipitate was filtered and washed with acetone. Dry weight is 1
2.0 g.

The results of elemental analysis were as follows: H: 3.52% C: 39.24% N: 8.28%
S: 13.78% Cl: 2.99% Composition: C ₂₄ H ₃₀ N _4.3 O ₁₅ S _3.2
Cl was _0.7 , and the S / N ratio (molar ratio between sulfur atoms and nitrogen atoms) was 0.73. This means that less than three sulfone groups are introduced for every four aromatic rings of polyaniline. The counterion Cl ^- doping ratio of 0.175 (35%)
It is.

As a result of measuring the solubility in water at room temperature,
It was 5.0% by weight.

The obtained sulfonated polyaniline was formed into pellets, and the electric conductivity was measured by a four-terminal method. As a result, it was found to be 5.72 × 10 ⁻³ S / cm.

(Preparation of Organic Nonlinear Optical Thin Film) Example 1 The sulfonated polyaniline obtained in Synthesis Example 1 was dissolved in ion-exchanged water to prepare a 5% solids aqueous solution, and spin-coated on a washed slide glass. Thus, a pale green transparent film was obtained. The surface resistance of this film is 6.3 ×
It was 10 ³ Ω / □.

Example 2 The sulfonated polyaniline obtained in Synthesis Example 1 was dissolved in ion-exchanged water, and neutralized with an aqueous sodium hydroxide solution until all of the sulfone groups became sodium salts and the undoping was completed. This aqueous solution was spin-coated on a washed slide glass to obtain a pale blue transparent film.

Example 3 The sulfonated polyaniline obtained in Synthesis Example 1 and polyacrylic acid manufactured by Aldrich (average molecular weight: 2,000) were dissolved in ion-exchanged water at a weight ratio of 1: 1 to give a 5% solids aqueous solution. Was prepared and spin-coated on a washed slide glass to obtain a pale green transparent film. The surface resistance of this polyaniline-polyacrylic acid resin composition film was 6.3 × 10 ⁹ Ω / □.

Example 4 2.1 g (0.01 mol) of tetraethoxysilane was dissolved in 20.0 g (0.43 mol) of ethanol, and while stirring, 1.8 g (0.1 mol) of distilled water and hydrochloric acid (0.1 mol) were dissolved. 0.51 g (0.005 mol) of a 36% aqueous solution was added dropwise. After completion of the dropwise addition, stirring was continued for 10 hours to obtain a silica gel dispersion, which was concentrated until the solid content became 10% by weight.

The sulfonated polyaniline obtained in Synthesis Example 1 and the silica sol dispersion were dissolved in ion-exchanged water at a weight ratio of 9: 1 to prepare a solution having a solid content of 5% by weight. This solution was spin-coated on a slide glass, and heated at 200 ° C. for 2 hours to obtain a pale green transparent film.

Example 5 17.5 g (0.15 mol) of ammonium vanadate was dissolved in 1000 g of distilled water. This aqueous solution of ammonium vanadate was passed through a strongly acidic ion exchange resin to obtain an aqueous solution of polyvanadate.

The sulfonated polyaniline obtained in Synthesis Example 1 and the aqueous solution of polyvanadic acid were dissolved in ion-exchanged water at a weight ratio of 4: 1 to prepare a solution having a solid content of 1% by weight. This solution was spin-coated on a washed slide glass to obtain a pale green transparent film.

(Measurement of Third-Order Nonlinear Susceptibility) Examples 1 to 5
Of the transparent film or transparent film was measured using a phase conjugate degenerate four-wave mixing method. For the measurement, the second harmonic (wavelength 532n) of the Nd: YAG laser was used.
m, pulse width 40 psec). The third-order nonlinear susceptibility of the sample χ ⁽³⁾ is determined by the reference substance (CS
It was calculated from the ratio of the reflectance R of the phase conjugate light to ₂ ) using the following equation (1).

[0050]

(Equation 1)

Here, L is the thickness of the medium, R is the reflectivity of the phase conjugate light, n is the refractive index, subscript S is the sample, subscript CS ₂
Represents carbon disulfide. Q is a correction coefficient defined by the following equation (2).

Q = ln (1−T) / T (1−T) (2) where T is the transmittance of the sample.

Table 1 summarizes the measurement results.

[0054]

[Table 1]

As apparent from Table 1, it was found that the transparent films or transparent films of Examples 1 to 5 exhibited a large third-order nonlinear optical effect. Further, no decomposition by laser light irradiation was observed at all, and it was found that the material had extremely high laser light resistance despite being an organic material.

[0056]

As described above, the organic nonlinear optical material of the present invention is characterized by using a water-soluble π-electron conjugated polymer. Therefore, it is possible to provide an organic nonlinear optical material that can be easily formed into a thin film and has a large third-order nonlinear susceptibility.

Continuing from the front page (72) Inventor Sakaguchi 1-8-31 Midorigaoka, Ikeda-shi, Osaka Industrial Technology Institute Osaka Industrial Technology Research Institute (72) Inventor Kazuhiko Murata 1-25-25 Kannondai, Tsukuba-shi, Ibaraki 12 shares Nippon Shokubai Co., Ltd. (72) Inventor Masatoshi Ito 1-25-12 Kannondai, Tsukuba City, Ibaraki Pref. Nippon Shokubai Co., Ltd. (72) Inventor Naruichi Teshima 1-25-25 Kannondai, Tsukuba City, Ibaraki Pref. (72) Inventor Yoshinobu Asako 1-25-12 Kannondai, Tsukuba, Ibaraki Pref.

Claims (3)

[Claims] 1. An organic nonlinear optical material using a water-soluble π-electron conjugated polymer. 2. An organic nonlinear optical material, wherein the water-soluble π-electron conjugated polymer according to claim 1 is a water-soluble polyaniline. 3. An organic nonlinear optical material using a mixture of the water-soluble π-electron conjugated polymer according to claim 1 and a water-soluble or water-dispersible polymer.