JPH06214271A - Organic nonlinear optical material - Google Patents

Abstract

PURPOSE:To obtain an org. nonlinear optical material having a large nonlinear optical effect and excellent formability by using coplymers consisting of specified structural units. CONSTITUTION:This material consists of coplymers having structural units expressed by formula I and formula II, containing 5-100mol% of the unit of formula I and 0-95mol% of the unit of formula II, and having 10000-2000000mol. wt. In formula I, (m) is an integer 1-10, (n) is 0 or 1, R<1> is a methyl group or phenyl group, X is -NR<2>-or -O-, and R<2> and R<3> are hydrogen atoms or methyl or ethyl groups, A is-NO2, -CN, -CF3, etc., Y is expressed by formula III, and R<4> is hydrogen or same as A. In formula II, Z is -COOR<5>, wherein R<5> is a hydrogen atom or lower alyl group. The polymer is synthesized in processes of polymn., hydrolysis, formation of acid chloride, and introduction of photofunctional groups.

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 a central role in such an optical element.

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
Electrons involved in chemical bonds between atoms and ions are accompanied by lattice vibrations in response to light, so that there is a 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 is poor when the optical fiber or the film is molded, for example.

[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), containing 5 to 100 mol% of the unit of the formula (I), formula
It contains 0 to 95 mol% of the unit (II) and has a molecular weight of 10,000 to 20.
It consists of 0,000 copolymers.

[0009]

[Chemical 4]

(In the formula (I), m represents an integer of 1 to 10, n represents 0 or 1, R ¹ represents an alkyl group or a phenyl group, and X represents —NR ² — or —O—. Represents, R ²
And R ³ are each a hydrogen atom, a methyl group or an ethyl group, A is -NO _2, -CN, -CF ₃ or -SO ₂ C
represents _p H _{2p + 1, p} represents an integer of 1 to 10, Y is

[0011]

[Chemical 5]

And R ⁴ represents hydrogen or the same as A)

[0013]

[Chemical 6]

(In the formula II, Z represents --COOR ⁵ , and R ⁵
Represents a hydrogen atom or a lower alkyl group)

The present invention will be described in detail below. The copolymer used in the present invention contains the unit of the formula (I) in an amount of 5 to 100 mol%, preferably 50 to 100 mol%, particularly preferably 5
0 to 98 mol%, the unit of the formula (II), Z is --COOR
⁵ alone, -COOH alone or -COOR ⁵
And -COOH in the total amount of 0 to 95 mol%, preferably 0 to 50 mol%, particularly preferably 2 to 4
Contains 0 mol%. Particularly preferably, the unit of formula (I) is 50
.About.98 mol%, 0.5 to 40 mol% of Z is COOR ⁵ and 0.5 to 40 mol% of Z is --COOH.

The molecular weight of the copolymer used in the present invention is 10,000 to 2,000,000, preferably 100,000 to 1,000,000. Next, the method for producing the copolymer 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 four steps of a polymerization step, a hydrolysis step, an acid chloride forming step and a photofunctional group introducing step. Also, the polymer can be produced by a synthetic route omitting the acid chloride formation step.

Polymerization process

[0019]

[Chemical 7]

(In the reaction formula, R ¹ , R ³ and R ⁵ are the same as above)

The substituted vinylidene cyanide and the acrylic acid derivative are copolymerized in the presence of a radical initiator to synthesize a copolymer of the substituted vinylidene cyanide and the acrylic acid derivative. The polymerization reaction can be performed by a conventional method.

The copolymer of the substituted vinylidene cyanide acrylic acid derivative, which is the raw material of the copolymer used in the present invention, may be an alternating copolymer or a random copolymer, but is preferably a 1: 1 alternating copolymer. Is.

The molecular weight of the copolymer of substituted vinylidene cyanide and an acrylic acid derivative is 10,000 to 2,000,000, preferably 100,000 to 1,000,000.

Hydrolysis step

[0025]

[Chemical 8]

(In the reaction formula, R ¹ , R ³ and R ⁵ are the same as above)

A part or all of the ester moiety of the copolymer obtained in the above step is hydrolyzed with an acid or a catalyst to obtain a carboxylic acid copolymer. Examples of the acid used here include hydrochloric acid, sulfuric acid, acetic acid, trifluoroacetic acid and the like. You may use these acids individually or 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 hydrolysis reaction temperature 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%.

Acid chloride formation step

[0031]

[Chemical 9]

(In the reaction formula, R ¹ and R ³ are the same as above)

The carboxylic acid copolymer obtained in the above step is dissolved in an organic solvent and heated with an acid chloride for several hours to convert it into an acid chloride copolymer. As the organic solvent used,
A solvent that completely dissolves the carboxylic acid and does not react with the chlorinated product or the acid chloride-containing copolymer that is formed is preferable, and examples thereof include sulfolane.

Examples of the acid chlorinated compound to be used include general chlorinating reagents such as oxalic acid chloride, thionyl chloride and phosphorus pentachloride. The heating temperature is 30 to 1
00 ° C is preferred.

Next, after completion of the reaction for several hours, the excess acid chlorinated compound is completely removed using a poor solvent to isolate the acid chloride copolymer. The poor solvent used is not particularly limited as long as it does not react with the acid chloride copolymer, and examples thereof include organic solvents such as toluene, benzene, and hexane.

Photofunctional group introduction step

[0037]

[Chemical 10]

(In the reaction formula, R ¹ , R ³ , m, n, X, Y
And A are the same as above)

The acid chloride copolymer obtained in (1) is redissolved in an organic solvent such as sulfolane, a base such as pyridine or triethylamine is added, and the mixture is heated together with the nonlinear optical compound to introduce the nonlinear optical compound partially or entirely. The obtained copolymer of the present invention is obtained. The non-linear optical compound has the following formula:

[0040]

[Chemical 11]

(In the formula, m, n, X, Y and A are the same as defined above), for example, p-nitroaniline and its derivatives, 4-hydroxy-4'-nitrobiphenyl and its derivatives, 4- Hydroxy-4'-nitrostilbene and its derivatives, 4-amino-4'-nitrostilbene and its derivatives, "Disperse Red 1"
ed 1 [manufactured by Aldrich]) derivatives and the like.

The heating temperature is preferably 50 to 100 ° C.

(Organic Nonlinear Optical Material) In the organic nonlinear optical material of the present invention, the copolymer thus obtained is prepared from dimethyl sulfoxide, N, N-dimethylacetamide,
It can be obtained by dissolving in a single solvent such as N, N-dimethylformamide or a solvent in which two or more kinds thereof are mixed and molding this.

As the molding method, a known molding method such as a solvent casting method, a spin coating method or a wet spinning method can be adopted. Further, the organic nonlinear optical material of the present invention can be formed by molding the obtained copolymer in a powder state, for example, by using a press molding method, an extrusion molding method or the like.

The organic nonlinear optical material of the present invention has a thickness or diameter of 0.1 to 1000 μm, preferably 1 to 500 μm.
Can be used after being processed into a film, sheet or fiber. When it is in the form of a film or a sheet, it is preferably stretched 2 to 6 times in order to enhance its orientation, and the stretching method in that case is mechanical uniaxial stretching or biaxial stretching. .

The organic nonlinear optical material of the present invention is obtained by molding a desired shape such as a film, sheet or fiber into
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 thereof and a voltage is applied to the metal coating film is mentioned. it can.

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

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 is 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. When the organic nonlinear optical material is formed by spin coating, the polymer is dissolved in a single solvent such as dimethyl sulfoxide or N, N-dimethylacetamide or a mixed solvent of the above solvent and acetonitrile or methanol, Spin coat on a Nessa glass,
Then, the organic non-linear optical material obtained by drying under reduced pressure can be polarized by using ordinary corona discharge. The conditions of the polarization treatment using corona discharge are the same as those in the case of the film-shaped or sheet-shaped organic nonlinear optical material described above.

[0050]

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 Synthesis of Vinylidene Cyanide-Methyl Methacrylate Copolymer MRS Weir et al. (Canadian J. Chem., 43, 772)
(1985)) 3,3-dicyano-2-propene 5 g (0.06 mol), methyl methacrylate 6 g
20 mg (0.12 mmol) of (0.06 mol) and 2,2'-azobis (isobutyronitrile) (AIBN) were degassed and sealed in an ampoule and polymerized at 70 ° C for 120 hours.

Thereafter, the tube was opened, methanol was added thereto, the polymer was separated by filtration, further thoroughly washed with methanol, and then dried under reduced pressure at 80 ° C. overnight. Product yield 0.8g
The yield was 9%.

The product was analyzed by ¹ H-NMR, ¹³ C-NM
Approximately 1: when analyzed by R, IR and elemental analysis.
It was confirmed to be 1 alternating copolymer. The glass transition temperature of this polymer was 123 ° C. Also GPC
(Gel permeation chromatography, N, N-
When the molecular weight was measured with a dimethylformamide solvent), the molecular weight (M _W ) of the obtained polymer was 70,000.

[0054]

[Chemical 12]

Hydrolysis of Vinylidene Methyl Cyanide-Methyl Methacrylate Copolymer 10 g of vinylidene cyanide-methyl methacrylate copolymer prepared by a conventional method is dissolved in 500 ml of sulfolane to prepare a mixture of 25 ml of trifluoroacetic acid and 50 ml of hydrochloric acid. And 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 filtered off, and washing with water was repeated until the washing solution became neutral. Next, it is dried under reduced pressure at 70 to 80 ° C. to give a hydrolyzate 6.9 represented by the following structural formula.
g was obtained as a white powder.

[0057]

[Chemical 13]

The resulting hydrolyzate was identified by ¹ H-NM.
_{R (400MHz, DMSO-d 6} ) was carried out by. From the result, it was found that the hydrolysis rate of the ester bond of the methyl methacrylate portion was 85%.

Introduction of Photofunctional Group into Hydrolyzate 1 g of the obtained hydrolyzate was dissolved in 50 ml of sulfolane at 80 ° C. Add 2 ml of oxalic acid chloride to this mixture,
Excess oxalic chloride was removed by triturating several times. This was again dissolved in 50 ml of sulfolane, 1 g of p-nitroaniline was added, and the mixture was heated and stirred at 60 ° C. for 7 hours to obtain 370 mg of a polymer having p-nitroaniline introduced into its side chain.

The glass transition temperature of this polymer is 129.
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 (M _W ) of the obtained polymer was 80,000.

The ¹ H-NMR chart of the obtained polymer is shown in FIG. The structure of the polymer determined based on the result is shown below.

[0062]

[Chemical 14]

Example 2 A polymer represented by the following structural formula was prepared in the same manner as in Example 1 except that 2 g of 4- (6-hydroxyhexyloxy) -4-nitrobiphenyl was used in place of 1 g of p-nitroaniline. 410 mg was obtained.

The glass transition temperature of this polymer is 123.
It was ℃. The structural formula of the polymer determined based on the result of ¹ H-NMR is shown below.

[0065]

[Chemical 15]

Example 3 Each of the polymers synthesized in Examples 1 and 2 was dissolved in dimethyl sulfoxide, spin-coated on Nesa glass and dried under reduced pressure to obtain a thin film. Corona polarization was performed on this spin coat film.

For the spin-coated film thus polarized, the method of Jerphagnon et al. [J. Appl. Phys., 41, 19]
67 (1970)], and the second-order nonlinear optical constant (d ₃₃ ) was measured. The results are shown in Table 1.

[0068]

[Table 1]

[0069]

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 5 to 100 mol% of the unit (I) is a unit.
An organic nonlinear optical material comprising 0 to 95 mol% of (II) and a copolymer having a molecular weight of 10,000 to 2,000,000. [Chemical 1] (In the formula (I), m represents an integer of 1 to 10, n represents 0 or 1, R ¹ represents an alkyl group or a phenyl group,
X is -NR ² - or an -O-, R ² and R ³ are each a hydrogen atom, a methyl group or an ethyl group, A is -N
Represents O ₂ , —CN, —CF ₃ or —SO ₂ C _p H _{2p + 1} , p represents an integer of 1 to 10, and Y represents And R ⁴ represents hydrogen or the same as A). (In the formula (II), Z represents —COOR ⁵ and R ⁵ represents a hydrogen atom or a lower alkyl group.)