JP3476535B2 - Photoisomerized polymer compound - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a novel photoisomerizable polymer compound. More specifically, it relates to a polymethacrylic acid derivative of azobenzene which is efficiently isomerized by light.

[0002]

2. Description of the Related Art Azobenzenes are converted from a trans form into a cis form by irradiation with ultraviolet rays, and the cis form is returned to the trans form by heating or irradiation with visible light. Utilizing this reversible molecular structure conversion, rewritable optical recording and application to control of various functions by optical energy have been attempted. For these purposes, a low molecular weight azobenzene is dissolved in a polymer in consideration of film formability, processability, and the like. However, this method has problems that low molecular weight azobenzene is eluted from the polymer and that mixing at high concentration is difficult.

Therefore, a polymer in which azobenzene is bonded to its main chain is used. For this purpose, a polymer compound has been obtained by synthesizing a monomer in which a polymerizable unit is bonded to the p-position of azobenzene and subjecting it to a known method such as radical polymerization or polycondensation reaction.

These azobenzene-substituted polymers generally have good film-forming properties, but the efficiency of photoisomerization from a trans form to a cis form by irradiating a film with light is low. . This is because photoisomerization is accompanied by a large change in molecular volume, and especially below the glass transition temperature at which the motion of the polymer main chain is constrained, the rate of this photogeometric isomerization decreases significantly. . Further, in the thermal isomerization from cis form to trans form, the influence of this polymer chain is large, and the isomerization that should be a one-molecule reaction is one of many components.
Since it involves the next reaction process, optical recording and optical control of material functions could not be performed linearly. Therefore, there has been a demand for higher efficiency of photoisomerization and a single component of thermal isomerization reaction.

[0005]

The present inventors have completed the present invention as a result of intensive studies to achieve the above object. That is, the present invention provides (1) the general formula (1)

[0006]

[Chemical 3]

(In the formula (1), X represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and Y represents a hydrogen atom, an alkoxy group having 1 to 6 carbon atoms or a carbon atom. Represents an acyloxy group of formula 1-6, Z is a hydrogen atom or an alkyl group, m is 0 or 1,
n represents an integer of 0 to 5) or a photoisomerizable monomer represented by the formula (2)

[0008]

[Chemical 4]

(In the formula (2), R is 1 to 4 carbon atoms.
Up to an alkyloxy group, an aryloxy group or a dimethylamino group), a polymethacrylic acid derivative characterized by copolymerizing with a monomer comprising a methacrylic acid derivative, (2) the general formula (1 ) The ratio (molar ratio) of the photoreactive monomer substituted with the azobenzene derivative represented by the formula (1) and the monomer comprising the methacrylic acid derivative represented by the general formula (2) is from 1: 0 to 1: (1) a polymethacrylic acid derivative which is between 10 and 10. This polymethacrylic acid derivative is different from the conventional azobenzene polymer compound in that a polymerizable residue is introduced at the o-position of the azobenzene skeleton.

In the above general formula (1), the carbon number of X is 1
Examples of the alkyl group of −6 include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group,
Examples thereof include an isobutyl group, a t-butyl group, an n-pentyl group, and an n-hexyl group. Examples of the alkoxy group having 1 to 6 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, an isopropoxy group, and n. -Butoxy group, isobutyloxy group, t-butyloxy group, n-pentoxy group, n
-Hexyloxy group and the like, and examples of the alkoxy group having 1 to 6 carbon atoms of Y include, for example, methoxy group, ethoxy group, n-propoxy group, isopropoxy group, n-butoxy group, isobutyloxy group, t-butyloxy group. Group, n-
Examples thereof include a pentoxy group and an n-hexyloxy group. Examples of the acyloxy group having 1 to 6 carbon atoms include an acetyloxy group, a propionyloxy group, a butyryloxy group,
Examples thereof include a valeryloxy group and a pentanecarbonyloxy group. Examples of the alkyl group of Z include carbon numbers such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group and a t-butyl group. 1-4 alkyl groups can be mentioned.

In the above general formula (2), the carbon number of X is 1
As the alkyloxy group of -4, for example, a methoxy group,
Ethoxy group, n-propyloxy group, isopropyloxy group, n-butyloxy group, isobutyloxy group, t-
Examples thereof include a butyloxy group and the like, and examples of the aryloxy group include a phenoxy group, a tolyloxy group, a xylyloxy group and the like.

To obtain the azo compound derivative of the present invention represented by the general formula (1), the general formula (3)

[0013]

[Chemical 5]

The aniline derivative compound represented by the formula (wherein X has the same meaning as described above) is diazotized by a known method to obtain a phenol having an alkyl group at the p-position, for example, diazo with p-cresol. A coupling reaction may be performed. Or general formula (4)

[0015]

[Chemical 6]

(In formula 4, A represents an acyloxy group, B represents a hydroxyl group or has the same meaning as the above-mentioned Y group), and if B is a hydroxyl group, then Alkylation or acylation is carried out by a known method. The compound of the general formula (5) is obtained by hydrolyzing the acyloxy group A in the azo compound derivative thus obtained.

[0017]

[Chemical 7]

(In the formula 5, X, Y and Z have the same meanings as described above.) The compound represented by the general formula (5) thus obtained is methacrylic acid by a known method, or its phenolic hydroxyl group is A monomer represented by the general formula (1) is produced by hydroxyalkylation and then methacrylation.

The photoreactive polymer of the present invention is prepared by polymerizing the monomer represented by the general formula (1) alone or by copolymerizing with the methacryl derivative represented by the general formula (2). The compound can be prepared. The amount of the methacrylic derivative represented by the general formula (2) to be copolymerized is preferably 100 mol or less with respect to 1 mol of the monomer represented by the general formula (1). More preferably, the amount of the methacryl derivative represented by the general formula (2) is about 0-10 mol per 1 mol of the monomer represented by the general formula (1). As the polymerization reaction, radical polymerization or ionic polymerization is used, but radical polymerization is particularly preferable, and either solution polymerization or emulsion polymerization may be used.

The polymer of the present invention shows good film-forming property,
What is more characteristic is that when the film is irradiated with ultraviolet rays,
It is a point to efficiently isomerize the trans isomer to the cis isomer despite the glass transition temperature or lower. Further, it was revealed that the cis-form produced by light irradiation is converted into the trans-form at a temperature below the glass transition temperature in the same manner as in the solution, following the primary reaction. None of these are things that occur in polymers where azobenzene is attached to the backbone at its p-position.

On the other hand, it is known that when a polymer film having azobenzene as a side chain is irradiated with linearly polarized light, the azobenzene groups are rearranged in a direction orthogonal to the plane of linearly polarized light, resulting in dichroism and birefringence. ing. If this is utilized, optical recording by linearly polarized light is possible, but the amount of light energy required therefor is a remarkably slow photosensitivity of several J / cm ² or more.
It was also clarified that an exposure energy of about 0 mJ / cm ² or less than one digit is sufficient. Such a preferable property, which is significantly different from that of the conventional p-substituted azobenzene-based polymer, is that the azobenzene group is bonded to the polymer main chain from its o-position, and the reason is as follows. Explained. That is, in the case of a p-substituted azobenzene polymer, since the p-position of azobenzene is fixed to the polymer chain, the volume change required for isomerization from the trans form to the cis form is very large. On the other hand, in the case of the polymer of the present invention, since azobenzene is bonded to the polymer main chain at the o-position, the volume change required for isomerization is minimal.

[0022]

INDUSTRIAL APPLICABILITY The polymer of the present invention is capable of easily photoisomerizing the azobenzene group even if it is below the glass transition temperature, and the thermal isomerization from cis form to trans form is a single component.
The next reaction proceeds. Due to such characteristics, it is preferably used for a reversible optical recording material.

Examples 1 to 4 4-phenylazoresorcinol-3 obtained from phenyldiazonium salt and resorcinol monobenzoate
Benzoate was reacted with methyl iodide in the presence of potassium carbonate in DMF. Hydrolyzing the product to give a melting point of 1
2-Hydroxy-4-methoxyazobenzene at 04-106 ° C was obtained as red needle crystals. This compound was reacted with 2-bromoethanol in DMF in the presence of potassium carbonate to obtain 2- (2-hydroxyethoxy) -4-methoxyazobenzene as a red liquid. This was reacted with methacrylic acid chloride in dehydrated benzene in the presence of triethylamine to obtain 2- (2-methacryloyloxyethoxy) -4-methoxyazobenzene having a melting point of 28 to 30 ° C as a yellow solid.

Elemental analysis: calc. (%) C: 67.06 H: 5.92 N: 8.23 found (%) C: 66.96 H: 6.08 N: 8.13 ¹ H-NMR (CDCl ₃ ): 1.90 (3H, S, C = C-CH ₃ ) 3.88 (3
H, S, ArO-CH ₃ ) 4.49 (4H, m, COO-CH _2- , ArO-CH _2- ) 5.55
(1H, S, C = CH) 6.11 (1H, S, C = CH) 6.61 (2H, m, Ar-H) 7.30
-7.98 (6H, m, Ar-H)

Azobisisobutyronitrile as an initiator was added to a 33 wt% benzene solution of this monomer so as to be 0.5 wt% with respect to this solution, freeze-deaerated and then sealed. It was kept at 60 to 65 ° C in a constant temperature bath and shaken for 12 hours. Reprecipitation purification with methanol was repeated until the presence of the monomer was not recognized from GPC. What was filtered from methanol was dissolved in benzene and freeze-dried.

Further, the molar amount of this monomer is
Methyl methacrylate was added so that the molar ratio was double and 99 times, and the polymerization was similarly carried out in benzene. The precipitate was reprecipitated in methanol, thoroughly washed with methanol, and then freeze-dried.

For these polymers, GPC measurement was carried out to determine the polystyrene reduced molecular weight. The DSC measurement was performed at a temperature rising rate of 10 ° C / min. The copolymerization ratio is
^It was calculated from the integral ratio of the benzene ring proton of azobenzene and the methyl group proton of MMA in ¹ H-NMR. The properties of the polymer thus obtained are summarized in Table 1 below.

These polymers were dissolved in toluene to prepare a 3% by weight solution, which was spin-coated on a slide glass to form a thin film. When this was irradiated with linearly polarized light of 435 nm, it was found that 8 to 10% of azobenzene was reoriented in the direction orthogonal to the polarized light irradiation surface at an exposure energy of 100 mJ / cm ² .

Examples 5 and 6 In the same manner as in Example 1, 2- (3-hydroxypropoxy) -4-methoxyazobenzene was obtained as a red liquid by using trimethylene chlorohydrin instead of 2-bromoethanol. It was From this, 4-methoxy-2- (3-methacryloyloxypropoxy) azobenzene was obtained in the same manner as a red liquid.

Elemental analysis: calc. (%) C: 67.78 H: 6.26 N: 7.91 found (%) C: 68.09 H: 6.29 N: 7.64 ¹ H-NMRδ (CDCl ₃ ): 1.90 (3H, S, C = C-CH ₃ ) 2.30
(3H, m, -CH _2- ) 3.91 (3H, S, ArO-CH ₃ ), 4.39 (4H, m, COO
-CH _2- , ArO-CH _2- ) 5.52 (1H, S, C = CH), 6.11 (1H, S, C = C-
H), 6.60 (2H, s, Ar-H), 7.20-8.00 (6H, m, Ar-H)

This monomer alone and 9 times the molar amount of methyl methacrylate were polymerized in benzene with azobisisobutyronitrile as the initiator. The product was reprecipitated in methanol, thoroughly washed with methanol, and then dried. The properties of the obtained polymer are summarized in Table 1 below. The copolymerization ratio was calculated from the integral ratio of the benzene ring proton of azobenzene to the methyl group proton of MMA in ¹ H-NMR.

These polymers were dissolved in toluene to prepare a 3 wt% solution, which was spin-coated on a slide glass to form a thin film. When this was irradiated with linearly polarized light of 435 nm, it was found that 8 to 10% of azobenzene was reoriented in the direction orthogonal to the polarized light irradiation surface at an exposure energy of 100 mJ / cm ² .

Examples 7 and 8 In the same manner as in Example 1, instead of 2-bromoethanol,
2- (5-Hydroxypentyloxy) -4-methoxyazobenzene was obtained as a red liquid using 5-chloropentanol. By the same operation as in Example 1, 4-methoxy-2
-(5-methacryloyloxypentyloxy) azobenzene was obtained as a red liquid.

¹ H-NMR (CDCl ₃ ): 1.80 (6H, m, -CH
_2- ) 1.92 (3H, S, C = C-CH ₃ ) 3.90 (2H, m, ArO-CH _2- ) 4.2
1 (4H, m, COO-CH _2- , ArO-CH _2- ) 5.52 (1H, S, C = CH) 6.09
(1H, S, C = CH) 6.59 (2H, d, Ar-H) 7.31-7.93 (6H, m, Ar-H)

This monomer alone and 9 times mol of methyl methacrylate were polymerized in benzene using azobisisobutyronitrile as an initiator. The product was reprecipitated in methanol, thoroughly washed with methanol, and then dried. The properties of the obtained polymer are summarized in Table 1 below. The copolymerization ratio was calculated from the integral ratio of the benzene ring proton of azobenzene to the methyl group proton of MMA in ¹ H-NMR.

These polymers were dissolved in toluene to prepare a 3 wt% solution, which was spin-coated on a slide glass to form a thin film. When this was irradiated with linearly polarized light of 435 nm, it was found that 8 to 10% of azobenzene was reoriented in the direction orthogonal to the polarized light irradiation surface at an exposure energy of 100 mJ / cm ² .

Example 9 10 4- (4-hexylphenylazo) resorcinol-3-monobenzoate (melting point: 134-136 ° C.) and 2-hydroxy-4-hexyloxy-4'-hexylphenylazobenzene from bromohexane to red Obtained as crystals. This hydroxyazobenzene was reacted with ethylene bromohydrin in DMF in the presence of potassium carbonate to obtain 4-hexyl-4'-hexyloxy-2 '-(2-hydroxyethoxy).
Azobenzene was obtained as a red liquid. The obtained hydroxyazobenzene was dissolved in toluene and reacted with methacrylic acid chloride in the presence of triethylamine to obtain 4-hexyl-4'-hexyloxy-2 '-(2-methacryloyloxyethoxy) -azobenzene as a yellow solid. . Yield: 7
8%, melting point: 45-46 ° C.

Elemental analysis: calc. (%) C: 72.84 H: 8.56 N: 5.64 found (%) C: 72.90 H: 8.47 N: 5.64 ¹ H-NMR (CDCl ₃ ): 0.89 (6H, d, CH ₃ ) 1.10-2.00
(16H, m, -CH _2- ) 1.93 (3H, S, C = C-CH ₃ ) 2.61 (2H, t, Ar-
CH _2- ) 4.00 (2H, m, ArO-CH _2- ) 4.50 (4H, m, COO-CH _2- ,
ArO-CH _2- ) 5.52 (1H, S, C = CH) 6.11 (1H, S, C = CH) 6.55
(2H, d, Ar-H) 7.26 (2H, d, Ar-H) 7.71 (3H, t, Ar-H)

This monomer alone and a mixture of 9-fold moles of methyl methacrylate were made into a 33 wt% benzene solution, and a polymerization initiator, azobisisobutyronitrile, was added to the solution at 0.5 wt% and frozen. After degassing, the tube was sealed. It was kept at 60 to 65 ° C in a constant temperature bath and shaken for 12 hours. The product was repeatedly reprecipitated and purified with methanol. What was filtered from methanol was dissolved in benzene and freeze-dried. The results are summarized in Table 1 below.

These polymers were dissolved in toluene to prepare a 3 wt% solution, which was spin-coated on a slide glass to form a thin film. When this was irradiated with 365 nm ultraviolet light, about 80% of the azobenzene changed from the trans form to the cis form at an exposure energy of 100 mJ / cm ² . It was also found that the cis isomer undergoes thermal isomerization to the trans isomer, but the reaction process is consistently primary from the initial stage to the final stage of the reaction.

Examples 11 and 12 2-Hydroxy-4-hexyloxy-4'-hexylazobenzene and 5-chloropentanol were reacted in the same manner as in Example 1 to give 4-hexyl-4'-hexyloxy-2'-. (5-hydroxypentyloxy) azobenzene was obtained as a red liquid. In the same manner as in Example 1, 4-hexyl-4′-hexyloxy-2 ′-(5-methacryloyloxypentyloxy) azobenzene was obtained as a red liquid.

Elemental analysis: calc. (%) C: 73.84 H: 9.01 N: 5.22 found (%) C: 74.78 H: 8.51 N: 5.26 ¹ H-NMR (CDCl ₃ ): 0.89 (6H, d, CH ₃ ) 1.17-2.05
(22H, m, -CH _2- ) 1.90 (3H, S, C = C-CH ₃ ) 2.65 (2H, t, Ar-
CH _2- ) 4.07 (4H, m, ArO-CH _2- ) 4.15 (2H, t, COO-CH _2- )
5.50 (1H, S, C = CH) 6.06 (1H, S, C = CH) 6.52 (2H, d, Ar-H)
7.26 (2H, d, Ar-H) 7.71 (3H, t, Ar-H)

This monomer alone and a mixture with 9 times mol of methyl methacrylate were made into a 33 wt% benzene solution, and a polymerization initiator, azobisisobutyronitrile, was added to the solution at 0.5 wt% and frozen. After degassing, the tube was sealed. It was kept at 60 to 65 ° C in a constant temperature bath and shaken for 12 hours. The product was repeatedly reprecipitated and purified with methanol. What was filtered from methanol was dissolved in benzene and freeze-dried. The results are summarized in Table 1 below.

These polymers were dissolved in toluene to prepare a 3% by weight solution, which was spin-coated on a slide glass to form a thin film. When this was irradiated with 365 nm ultraviolet light, about 80% of the azobenzene changed from the trans form to the cis form at an exposure energy of 100 mJ / cm ² . It was also found that the cis isomer undergoes thermal isomerization to the trans isomer, but the reaction process is consistently primary from the initial stage to the final stage of the reaction.

[0045]

[Table 1] Preparation composition ratio Molecular weight Tg Yield Example (monomer: MMA) Mw (X10 ^-4 ) Mw / Mn (° C) (%) 1 1: 0 1: 0 13.1 2.63 72 85 2 1: 1 1 1: 1.2 1.94 2.90 79 75 3 3 1: 9 1: 9.2 3.90 3.47 84 66 4 1:99 1: 120 3.69 1.98 112 74 5 1: 0 1: 0 6.65 2.99 61 75 6 1: 9 1: 11.6 3.35 2.34 93 78 7 1: 0 1: 0 10.5 2.63 36 78 8 1: 9 1: 9.1 4.39 1.98 80 69 9 1: 0 1: 0 7.37 2.29 <room temperature 86 10 1: 9 1: 9.8 18.8 2.25 84 69 11 1: 0 1: 0 9.43 2.48 <room temperature 80 12 1: 9 1: 10.3 19.5 2.49 69 74

Examples 13 and 14 In the same manner as in Example 1, 2-hydroxyl-5-methylazobenzene was obtained as red crystals from aniline and p-cresol. Yield: 74%, melting point: 100-101 ° C. ¹ H-NMR (CDCl ₃ ) δ (ppm): 2.41 (3H, s, C-CH ₃ ).
6.98 (1H, d, arom-H) 7.16 (1H, d, arom-H) 7.51 (3H, m, arom
-H) 7.80 (3H, m, arom-H)

This azobenzene was reacted with ethylene bromohydrin in the same manner as in Example 1 to obtain 2- (2-hydroxyethyl) -5-methylbenzene as a red liquid. Yield: 86%. In exactly the same manner as in Example 1, 4
-Methoxy-2- (3-methacryloyloxyethoxy)
Azobenzene was obtained as red crystals. Yield 75%. Melting point: 35-38 ° C.

¹ H-NMR (CDCl ₃ ) δ (ppm): 1.90 (3
H, s, C = C-CH ₃ ) 2.41 (3H, s, C-CH ₃ ) 4.49 (4H, m, COO-CH ₂
-, ArO-CH _2- ) 5.55 (1H, S, C = CH) 6.11 (1H, S, C = CH), 6.9
8 (1H, d, arom-H) 7.16 (1H, d, arom-H) 7.51 (3H, m, arom-H)
7.80 (3H, m, arom-H)

A mixture of this monomer alone and a 9-fold molar amount of methyl methacrylate was used as a 33 wt% benzene solution, and a polymerization initiator, azohisisobutyronitrile, was added to the solution in an amount of 0.5 wt% and freeze-thawed. After being careful, I sealed the tube. It was kept at 60 to 65 ° C in a constant temperature bath and shaken for 12 hours. The product was repeatedly reprecipitated and purified with methanol. What was collected by filtration from methanol was dissolved in benzene and freeze-dried. The molecular weights of these copolymers were 9.8 × 10 ⁴ and 13.3 × 10 ⁴ , respectively. Also, NM
From the R spectrum, the composition ratio of the copolymer was 1: 9.3. The homopolymer was dissolved in toluene to give a 3 wt% solution, which was spin-coated on a slide glass to form a thin film. When it was irradiated with ultraviolet rays of 365 nm,
About 80 of azobenzene with exposure energy of mJ / cm ^2.
% Changed to the trans form. It was also found that the cis isomer undergoes thermal isomerization to the trans isomer, but the reaction process is consistently primary from the initial stage to the final stage of the reaction.

Examples 15 to 17 2- (2-methacryloyloxyethoxy) -4-methoxyazobenzene shown in Example 1 and 9 times moles of butyl methacrylate, phenyl methacrylate and dimethylacrylamide were added to 33% by weight of benzene. As a solution,
Polymerization was performed using 0.5 wt% azobisisobutyronitrile as a polymerization initiator. After being kept at 60 to 65 ° C. in a thermostat for 12 hours and shaken, the produced polymer was reprecipitated in a poor solvent to be isolated and vacuum dried. The polystyrene-equivalent molecular weights (Mw) are 8.9 × 10 ⁴ and 7.5 ×, respectively.
It was 10 ⁴ and 6.3 × 10 ⁴ . When these polymer solutions were spin-coated on a quartz glass plate and irradiated with ultraviolet rays of 365 nm, the isomerization rates of azobenzene from the trans form to the cis form were 94%, 93%, and 95%, respectively. Further, under irradiation with light of 436 nm, the cis isomers were 31%, 33%, and 30%, respectively.

Claims (2)

(57) [Claims] 1. A general formula (1): (In the formula (1), X represents a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and Y
Represents an alkoxy group having 1 to 6 carbon atoms or an acyloxy group having 1 to 6 carbon atoms, Z is a hydrogen atom or an alkyl group, m is 0 or 1, and n is an integer of 0 to 5). The photoisomerizable monomer represented by the formula (1) is polymerized alone, or is used together with the photoisomerizable monomer represented by the general formula (2): (In the formula (2), R represents an alkyloxy group having 1 to 4 carbon atoms, an aryloxy group or a dimethylamino group) and is copolymerized with a monomer composed of a methacrylic acid derivative. And a polymethacrylic acid derivative. 2. A use ratio (mole) of the photoisomerizable monomer substituted with the azobenzene derivative represented by the general formula (1) and the monomer consisting of the methacrylic acid derivative represented by the general formula (2). The polymethacrylic acid derivative according to claim 1, wherein the ratio) is between 1: 0 and 1:10.