JPH06281978A - Organic nonlinear optical material - Google Patents

Abstract

PURPOSE:To provide the org. nonlinear optical material having a high nonlinear optical effect and excellent moldability. CONSTITUTION:This org. nonlinear optical material is a polymer which consists of the constitutional units expressed by formulas I and II. The unit expressed by the formula I is 0.1 to 100mol% and the unit expressed by the formula II is 0 to 99.9mol%. The mol. wt. of the polymer is 10.000 to 2,000,000. In the formulas, m denotes an integer from 1 to 10; n denotes an integer from 1 to 3; R1 denotes methyl group or ethyl group; R2 denotes -NO2, -CN, -CF3, -C(CN)= C(CN)2 or -CH=C(CN)2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical material useful as an optical element used in the fields of optical communication and optical information processing,
In particular, it relates to an organic nonlinear optical material having a nonlinear optical effect and excellent in mechanical strength and moldability.

[0002]

2. Description of the Related Art In order to apply a laser to optical communication, optical information processing, optical processing, etc., an optical element having various functions such as deflection, modulation or wavelength conversion is required. An optical material having a non-linear optical effect is known to play an essential role.

Conventionally, LiNbO has been used as a nonlinear optical material.
Inorganic crystals such as ₃ , LiIO, KH ₂ PO ₄ , and GaAs have been mainly studied.

However, these inorganic crystals are
Since electrons involved in chemical bonds between atoms and ions are accompanied by lattice vibration in response to light, there is the drawback that it is difficult to respond faster than picoseconds, and the breakdown threshold for intense laser light is low, It had the drawback of being on the order of MW / cm ² . Further, since these inorganic crystal bodies are generally used as single crystals, they have various practical drawbacks such as low mechanical strength, particularly impact strength, and poor moldability.

As the nonlinear optical material, urea, p
Organic molecular crystals such as -nitroaniline (p-NA) and 2-methyl-4-nitroaniline (MNA) are known. These organic molecular crystals have intramolecular delocalization π
It has a large non-linear optical effect due to electrons, and because it is not affected by lattice vibration due to this electronic polarization, it exhibits a faster response and a higher optical breakdown threshold than an inorganic crystal.

However, these organic molecular crystalline materials are required to have a large non-linear optical effect because they are single crystals, like the inorganic crystalline materials. The strength and the thermal stability are insufficient, the handling thereof is extremely difficult, and the workability thereof is poor when it is molded into, for example, an optical fiber or a film.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic nonlinear optical material having a large nonlinear optical effect and excellent moldability.

[0008]

The organic nonlinear optical material of the present invention comprises structural units represented by the following general formulas (I) and (II), wherein the unit (I) is 0.1 to 100 mol%, (I
I) is 0 to 99.9 mol% and the molecular weight is 10,000 to 20.
It is an organic nonlinear optical material characterized by being a polymer of 0,000.

[0009]

[Chemical 3]

(In the formula, m represents an integer of 1 to 10, n represents an integer of 1 to 3, R ₁ represents a methyl group or an ethyl group, and R ₂ represents --NO ₂ , --CN, --CF. ₃ , -C (CN)
= C (CN) ₂ or -CH = C (CN) ₂ )

[0011]

[Chemical 4]

The present invention will be described in detail below. The polymer used in the present invention has a unit (I) of 0.1 to 100 mol%,
It is preferably 1 to 100 mol%, and the unit (II) is 0 to 9
It is 9.9 mol%, preferably 0 to 99 mol%. The molecular weight of the polymer used in the present invention is 10,000 to 2,000,000, preferably 50,000 to 1,000,000. Next, a method for producing the polymer used in the present invention will be described.

Method for Producing Polymer The polymer used in the present invention can be synthesized, for example, through the following three steps of a polymerization step, a hydrolysis step, and a photofunctional group introducing step.

Polymerization process

[0015]

[Chemical 5]

(In the above reaction formula, R ₃ represents an alkyl group)

Vinylidene cyanide and vinyl p-alkylcarbonyloxybenzoate are copolymerized in the presence of a radical initiator to synthesize a vinylidene cyanide-p-alkylcarbonyloxy vinyl benzoate copolymer.
The polymerization reaction can be performed by a conventional method.

The vinylidene cyanide-p-alkylcarbonyloxy vinyl benzoate copolymer, which is a raw material of the polymer used in the present invention, may be either an alternating copolymer or a random copolymer, but preferably 1: 1 alternating. It is a copolymer.

The vinylidene cyanide-p-alkylcarbonyloxy vinyl benzoate copolymer has a molecular weight of 10,000 to 10,000.
It is 2,000,000, preferably 50,000 to 1,000,000.

Hydrolysis step

[0021]

[Chemical 6]

(In the above reaction formula, R ₃ is the same as above)

The resulting vinylidene cyanide-p-alkylcarbonyloxy vinyl benzoate copolymer is hydrolyzed with an acid or a catalyst to give a deacylated product. Examples of the acid used here include hydrochloric acid, sulfuric acid, acetic acid, trifluoroacetic acid and the like. These acids may be used alone or 2
You may use it in combination of 2 or more types.

These acids can be used by mixing with alcohols such as sulfolane, methanol and ethanol, and solvents such as water. Examples of the catalyst include silane compounds such as phenylsilane and tin compounds.

The reaction temperature for hydrolysis is 60 to 100 ° C., and the reaction time is several hours to several tens hours. The hydrolysis rate is 5 to 100%, preferably 50 to 100%.

Photofunctional group introduction step

[0027]

[Chemical 7]

(In the formula, m, n, R ₁ and R ₂ are the same as above)

The polymer used in the present invention can be obtained by redissolving the obtained copolymer in an organic solvent such as sulfolane, adding a base such as pyridine or triethylamine, and heating it together with the introduced nonlinear optical compound. .

Examples of the nonlinear optical compound to be introduced include azobenzene derivatives, diazobenzene derivatives or triazobenzene derivatives having an electron-withdrawing group such as a nitro group and a cyano group and an electron-donating group such as an alkylamino group.

The proportion of the non-linear optical compound introduced into the copolymer is 5 to 100 relative to the phenol in the copolymer.
%, Preferably 50 to 100%. The heating temperature is 5
0-100 degreeC is preferable. The molecular weight of the polymer is 10,000 to 20
It is from 0,000, preferably from 50,000 to 1,000,000.

(Organic Nonlinear Optical Material) When the organic nonlinear optical material of the present invention is in the form of a film or sheet, it is preferably stretched 2 to 6 times in order to enhance its orientation. Mechanical stretching is preferably uniaxial stretching or biaxial stretching.

The organic nonlinear optical material of the present invention is obtained by molding a film, sheet, fiber or the like into a desired shape.
By electrically polarization, the nonlinear optical effect can be increased. As a method of electrically polarizing, for example, when the organic nonlinear optical material is in the form of a film or a sheet, a method in which a metal coating film as an electrode is adhered to both surfaces of the material and a voltage is applied to the metal coating film is used. it can.

Examples of the electrode provided on the organic nonlinear optical material include a metal foil, a metal plate, a conductive paste or a metal coating film formed by chemical plating, vacuum deposition or sputtering.

The voltage applied to the electrodes is 10 kV / cm or more and the electric field strength is such that dielectric breakdown does not occur, and preferably 100 to 1500 kV / cm. The time of polarization treatment is not particularly limited, and is 10 minutes to 5 hours, preferably 10 minutes.
Minutes to 2 hours.

The temperature of the polarization treatment is Tg-20, where Tg is the glass transition temperature of the organic nonlinear optical material to be treated.
℃ ~ Tg + 20 ℃, preferably Tg -5 ℃ ~ Tg + 5 ℃
Is. Further, when the organic nonlinear optical material is formed by spin coating, a method is used in which the organic nonlinear optical material obtained by spin coating on Nesa glass and then drying under reduced pressure is polarized using ordinary corona discharge. be able to.

[0037]

EXAMPLES Next, the present invention will be described more specifically by showing examples, but the present invention is not limited to these examples.

Example 1 Synthesis of Copolymer Used in Organic Nonlinear Optical Material Hydrolysis of Vinylidene Cyanide-p-Acetoxyvinyl Benzoate Copolymer Vinylidene cyanide-p-methylcarbonyloxyvinyl benzoate prepared by a conventional method 10 g of the copolymer was dissolved in 500 ml of sulfolane at 80 ° C., 50 ml of hydrochloric acid was added thereto, and the mixture was stirred at 80 ° C. for 5 hours. After the reaction was completed, the hydrolyzate that had precipitated by pouring the reaction solution into water was separated by filtration and washed repeatedly with water until the washing solution became neutral. Next, it was dried under reduced pressure at 70 to 80 ° C. to obtain 7.7 g of a hydrolyzate represented by the following structural formula as a white powder.

The vinylidene cyanide used was -p-.
The acetoxy vinyl benzoate copolymer has an average molecular weight of 43.
It was good. The resulting hydrolyzate was identified by ¹ H-NM
_{R (400MHz, DMSO-d 6} ) was carried out by. From the results, it was found that the hydrolysis rate of the ester portion of the vinyl benzoate unit was 100%.

[0040]

[Chemical 8]

Synthesis of Photofunctional Group

[0042]

[Chemical 9]

Disperse Red 1 25 g (0.08 mol,
Aldrich) is N, N-dimethylformamide 1250
This was dissolved in ml, 40 g of succinic anhydride (0.4 mol, manufactured by Wako Pure Chemical Industries, Ltd.) was added, and the mixture was reacted at 100 ° C for 24 hours to obtain 32 g of the desired carboxylic acid. mp169-17
0 °.

Synthesis of acid chloride of Disperse Red 1 carboxylic acid 1 g (2.42 mmol) of the above-mentioned carboxylic acid was reacted with 2 ml of oxalic acid chloride in 10 ml of benzene at room temperature for 24 hours to obtain the desired acid chloride.

Introduction of Photofunctional Group into Hydrolyzate 1 g (4.13 mmol) of the above hydrolyzate of vinylidene cyanide-p-methylcarbonyloxybenzoic acid copolymer was dissolved in 50 ml of sulfolane at 80 ° C. To this solution was added a solution of the acid chloride obtained above in 20 ml of sulfolane, and 0.33 g (4.18 mmol) of pyridine.
Was added and the mixture was stirred at 80 ° C. for 6 hours. Next, the obtained reaction liquid was poured into methanol, the precipitated polymer was separated by filtration, washed with methanol several times, and dried under reduced pressure to obtain 1.1 g of a polymer represented by the following structural formula.

The glass transition temperature of this polymer is 195.
It was ℃. Also, GPC (gel permeation chromatography, N, N-dimethylformamide solvent)
As a result of measuring the molecular weight by the method, the molecular weight (MW) of the obtained polymer was 440,000.

The ¹ H-NMR chart of the obtained polymer is shown in FIG. The arrow indicates the peak derived from the side chain-introduced functional group. Each unit ratio in the polymer determined based on the result is shown in the following structural formula.

[0048]

[Chemical 10]

The polymer synthesized in Example 1 was dissolved in dimethyl sulfoxide, spin-coated on Nesa glass and dried under reduced pressure to obtain a thin film. Corona polarization was applied to this spin coat film.

Regarding the spin-coated film thus polarized, the method of Jerphagnon et al. [J. Appl. Phys., 41, 1967.
(1970)], and the second-order nonlinear optical constant (d ₃₃ ) was measured. The results are shown in Table 1.

[0051]

[Table 1]

[0052]

Industrial Applicability The organic nonlinear optical material of the present invention has a large nonlinear optical effect and is excellent in molding processability. Therefore, the optical wavelength conversion element, the optical shutter, the optical polarization element, the optical intensity, the phase modulation element, the high speed optical element. It is useful as an optical material such as an optical switching element, and can be widely applied to the fields of optical communication, optical information processing, and optical processing. Further, the organic nonlinear optical material of the present invention, not only wavelength conversion and electro-optical effect,
It is also excellent in piezoelectric and pyroelectric effects, so speakers,
It can be widely applied to various sensors such as headphones, ultrasonic elements, impact sensors, acceleration sensors, and various detectors such as infrared sensors, crime prevention sensors, temperature sensors, and fire detection.

[Brief description of drawings]

FIG. 1 is a ¹ H-NMR chart of the polymer obtained in Example 1.

Claims (1)

[Claims] 1. A structural unit represented by the following general formulas (I) and (II), wherein the unit (I) is 0.1 to 100 mol%,
An organic nonlinear optical material, which is a polymer having a unit (II) of 0 to 99.9 mol% and a molecular weight of 10,000 to 2,000,000. [Chemical 1] (In the formula, m represents an integer of 1 to 10, n represents an integer of 1 to 3, R ₁ represents a methyl group or an ethyl group, and R ₂ represents −.
_{NO 2, -CN, -CF 3,} -C (CN) = C (CN)
₂ or -CH = C (CN) ₂ )