JP2010174199A - Block copolymer and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a block copolymer which has narrower molecular weight distribution than that of a polymer obtained by usual radical polymerization and has controlled molecular weight and to provide a method for producing the same. <P>SOLUTION: In the production method of the block copolymer having a repeating unit of a first monomer and a repeating unit of a second monomer, the second monomer is subjected to optical living radical polymerization in the presence of a compound having a 2,2,6,6-tetramethylpiperidin-1-oxyl at a terminal of the repeating unit of the first monomer, to produce the block copolymer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a block copolymer synthesized by photo-living radical polymerization using a polymer mediator and a method for producing the same.

Conventionally, a method of synthesizing a block copolymer by living polymerization is well known, and living polymerization includes living anion polymerization, living cation polymerization, living radical polymerization, and the like. Living radical polymerization does not require strict management of polymerization conditions compared to living anionic polymerization or living cationic polymerization, so the advantage is that the technique is simple, the advantage is that the range of applicable monomers is wide, and so on.
On the other hand, among radical polymerizations, photo radical polymerization, which is initiated by light, is not only clean and energy-saving compared to radical polymerization initiated by heat, but is preferable from the viewpoint of environmental conservation. It is excellent in that it can be applied to a manufacturing process in which heat cannot be applied, and it can be applied to a minute part. Taking advantage of such advantages, radical photopolymerization is applied to various fields such as coating, printing, and photography.
However, in the conventional photo-living radical polymerization, it is difficult to control the molecular weight, and the molecular weight distribution of the resulting block copolymer is the molecular weight distribution of the polymer obtained by ordinary radical polymerization (weight average molecular weight / number average). There is a problem that the molecular weight is equivalent to 2.0 to 3.3).

  In order to solve such problems, various new photo-living radical polymerization systems have been developed, but in order to narrow the molecular weight distribution, it is necessary to suppress the monomer conversion to 50% or less. There arises a new problem such as difficulty in obtaining a block copolymer in a high yield.

  On the other hand, in conventional living polymerization, the types of monomers that can be applied to each living polymerization are determined. Therefore, a block copolymer having a structure in which polymers generated by different types of polymerization are combined by one type of polymerization method. It is impossible to synthesize a polymer. In order to synthesize such a block copolymer between different types of polymers, there is a method in which polymers are bonded to each other by a polymer reaction after polymerization. However, in order to bond the polymers together, it is necessary to introduce reactive functional groups quantitatively at the ends of the polymers, and to react quantitatively between the reactive functional groups. become. In addition, when a polymerization conversion method is used, it is possible to synthesize a block copolymer between different types of polymerization, but there is a problem that stricter polymerization conditions are required.

An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide a block copolymer having a molecular weight distribution narrower than that of a polymer obtained by ordinary radical polymerization and having a controlled molecular weight, and a method for producing the same.
Moreover, it aims at providing the manufacturing method of the block copolymer which can manufacture the block copolymer between different types of polymerization with 1 pot, without using the polymeric reaction and the conversion method of superposition | polymerization.

  Furthermore, the present invention provides a new function or performance by controlling the molecular weight of the block copolymer to express a higher performance function in the block copolymer, and by synthesizing the block copolymer between different polymers. The purpose is to develop materials with

As a result of intensive studies to achieve the above object, the present inventors have found 2,2,6 at the end of a polymer (a repeating unit of the first monomer) obtained by a polymerization method other than radical polymerization. , 6-tetramethylpiperidine-1-oxyl (TEMPO) introduced into the compound represented by the following general formula (1) as a polymer mediator, and a second single monomer by a radical polymerization initiator in the presence of a photoacid generator. It has been found that by performing photo-living radical polymerization of a monomer, a block copolymer between different types of polymers having a controlled molecular weight can be synthesized in one pot, and the present invention has been completed.

  In particular, when the compound represented by the above general formula (1) is used as a polymer mediator and a monomer is subjected to photo-living radical polymerization using an azo radical polymerization initiator in the presence of a photoacid generator, radical polymerization is performed. The polymer (polymeric unit of the first monomer) in the polymer mediator produced by a polymerization method other than the polymer (the second monomer of the second monomer) produced by the photo-living radical polymerization of the second monomer It has been found that a block copolymer in which a repeating unit is bonded via 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) can be obtained with a narrow molecular weight distribution.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A method for producing a block copolymer having a repeating unit of a first monomer and a repeating unit of a second monomer, the terminal of the repeating unit of the first monomer being A block copolymer is produced by photo-living radical polymerization of the second monomer in the presence of a compound having 2,2,6,6-tetramethylpiperidine-1-oxyl. It is a manufacturing method of a block copolymer.
<2> The method for producing a block copolymer according to <1>, wherein the photo-living radical polymerization is initiated by a radical polymerization initiator and performed in the presence of a photoacid generator.
<3> The method for producing a block copolymer according to <2>, wherein the repeating unit of the second monomer is represented by the following general formula (2).
In general formula (2), R ¹ represents a radical polymerization initiator residue, and R ² represents an alkyl group. The alkyl group may contain at least one of a perfluoroalkyl group, a hydroxy group, an amino group, and a glycidyl group. n represents an arbitrary positive number.
<4> A block copolymer produced by the method for producing a block copolymer according to any one of <1> to <3>.

  According to the present invention, the conventional problems can be solved and the object can be achieved. That is, it is possible to provide a block copolymer having a molecular weight distribution narrower than that of a polymer obtained by ordinary radical polymerization and having a controlled molecular weight, and a method for producing the same.

FIG. 1A is a 1H-NMR spectrum of the block copolymer obtained in Example 1. FIG. 1B is an enlarged view of the 1H-NMR spectrum of FIG. 1A. FIG. 1C is a structural formula of the block copolymer obtained in Example 1.

  Hereinafter, the block copolymer of the present invention and the details of the production method thereof will be specifically described. However, the scope of the present invention is not limited to these descriptions, and the present invention is not limited to the following examples. It can implement suitably in the range which does not impair the meaning.

(Method for producing block copolymer)
The method for producing a block copolymer of the present invention includes at least a photo-living radical polymerization step, and further includes other steps appropriately selected as necessary.

<Optical living radical polymerization process>
In the photo-living radical polymerization step, the second monomer is added in the presence of a compound having 2,2,6,6-tetramethylpiperidine-1-oxyl at the terminal of the repeating unit of the first monomer. This is a process of photo-living radical polymerization.

<< Compound >>
The compound is a polymer mediator having a 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) at the terminal of the repeating unit of the first monomer (represented by the following general formula (1) The compound is not particularly limited as long as it is a compound), and can be appropriately selected according to the purpose. The end may be either one end or both ends.

The repeating unit of the first monomer is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include polyether, polyester, polyamide, polycarbonate, and polyurea.
There is no restriction | limiting in particular as number average molecular weight (Mn) of the said compound, Although it can select suitably according to the objective, 500-30,000 are preferable and 1,000-5,000 are more preferable.

  The compound is obtained, for example, by a living anionic polymerization of a lactone using a metal salt of 4-hydroxy-TEMPO as an initiator, a reaction between a growth terminal of a ring-opening living cationic polymerization of a cyclic ether and 4-sodiumoxy-TEMPO, or the like. It is done. The compound can be synthesized by reacting a polymer obtained by polycondensation with both ends capped with 2,4-toluene diisocyanate and 4-hydroxy-TEMPO.

The compound binds to the growing terminal radical generated by the radical polymerization initiator attacking the second monomer, and, as shown in the following reaction formula (1), the polymer mediator and the growing terminal radical Between, recombination and dissociation are repeated to control the molecular weight.

  There is no restriction | limiting in particular as molar ratio of the said compound, Although it can select suitably according to the objective, 1 mol-2 mol are preferable with respect to 1 mol of radical polymerization initiators mentioned later.

<< second monomer >>
There is no restriction | limiting in particular as said 2nd monomer, According to the objective, it can select suitably, For example, a methacrylic acid ester derivative is mentioned.
The methacrylic ester derivative is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, perfluoroalkyl methacrylate, 2-hydroxy methacrylate. And ethyl, glycidyl methacrylate, 2-dimethylaminoethyl methacrylate, and the like. Two or more of these methacrylic acid ester derivatives may be used in combination.

The repeating unit of the second monomer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably represented by the following general formula (2).
In general formula (2), R ¹ represents a residue of a radical polymerization initiator described later, and R ² represents an alkyl group. The alkyl group may contain at least one of a perfluoroalkyl group, a hydroxy group, an amino group, and a glycidyl group. n represents an arbitrary positive number.

<< Optical Living Radical Polymerization >>
The photo-living radical polymerization is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably initiated by a radical polymerization initiator and carried out in the presence of a photo acid generator.
There is no restriction | limiting in particular as a light source used for the said photoliving radical polymerization, Although it can select suitably according to the objective, A high pressure mercury lamp is preferable and the ultra high pressure mercury lamp which has an output of 400 W or more is more preferable.

  There is no restriction | limiting in particular as reaction temperature of the said photoliving radical polymerization, Although it can select suitably according to the objective, Room temperature of 25 degreeC or more is preferable.

<<< Radical polymerization initiator >>>
There is no restriction | limiting in particular as said radical polymerization initiator, According to the objective, it can select suitably, For example, an azo initiator etc. are mentioned.
The 10-hour half-life temperature of the azo initiator is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20 ° C to 80 ° C, and more preferably 25 ° C to 70 ° C.
The radical polymerization initiator is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include azobisisobutyronitrile, 2,2′-azobis (2,4-dimethylvaleronitrile), 2 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (isobutyric acid) dimethyl, 1,1 ′ -Azobis (cyclohexane-1-carbonitrile), 2,2'-azobis- [2- (2-imidazolin-2-yl) propane], 2,2'-azobis {2-methyl-N- [1,1 -Bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, and the like.
There is no restriction | limiting in particular as molar ratio of the said radical polymerization initiator, Although it can select suitably according to the objective, 0.001 mol-0.01 with respect to 1 mol of said 2nd monomer total amounts. Mol is preferable, and 0.0015 mol to 0.005 mol is more preferable.

<<< photo acid generator >>>
The photoacid generator is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include iodonium salts represented by the following general formula (3). Among these, an iodonium salt in which an alkyl group is introduced into an aromatic group is preferable in terms of high solubility in various compounds.
In the general formula (3), n represents an integer.
In the general formula (3), n representing the number of carbon atoms of the methylene group is not particularly limited as long as it is an integer, and can be appropriately selected according to the purpose. More preferred.

  There is no restriction | limiting in particular as molar ratio of the iodonium salt represented by the said General formula (3), Although it can select suitably according to the objective, 0.5 mol or less is preferable with respect to 1 mol of said compounds. .

(Block copolymer)
The block copolymer of the present invention is not particularly limited as long as it is produced by the method for producing a block copolymer of the present invention, and can be appropriately selected according to the purpose. ) Is preferable.

In the general formula (4), R ¹ represents a radical polymerization initiator residue, and R ² represents an alkyl group. The alkyl group may contain at least one of a perfluoroalkyl group, a hydroxy group, an amino group, and a glycidyl group. n represents an arbitrary positive number.
In the block copolymer, a polymer mediator (compound having TEMPO at the terminal) forms part of a segment, and a polymer (polymer of the first monomer is repeated) in the polymer mediator (compound having TEMPO at the terminal). Unit) and a polymer (a repeating unit of the second monomer) generated by photoradical living polymerization of the second monomer are bonded via TEMPO.

There is no restriction | limiting in particular as number average molecular weight (Mn) of the said block copolymer, According to the objective, it can select suitably, For example, it is about 5,000-30,000.
There is no restriction | limiting in particular as molecular weight distribution (Mw / Mn) of the said block copolymer, According to the objective, it can select suitably, For example, it is 1.4-1.9.
However, when a polymer mediator (compound having TEMPO at the terminal) having a molecular weight of 10,000 or more is used, the polymer (first monomer) that is the main chain of the polymer mediator (compound having TEMPO at the terminal) And the polymer produced by the photoradical living polymerization of the second monomer (repeating unit of the second monomer) is low in compatibility, and the polymerization system becomes cloudy in the polymerization step. The molecular weight distribution of the block copolymer is 2.0 to 4.0.

Example 1
A commercially available methyl methacrylate monomer was washed with a 5% by weight aqueous sodium hydroxide solution and then distilled under reduced pressure in the presence of calcium hydride to remove the radical polymerization inhibitor.
To 1 mL of the purified methyl methacrylate monomer, 7 mg of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) as a radical polymerization initiator and bis (alkylphenyl) as a photoacid generator 19 mg of a 50 wt% propylene carbonate solution of iodonium hexafluorophosphate and 24 mg of one-end-TEMPO-modified polytetrahydrofuran as a polymer mediator were dissolved.
Here, the carbon number n of the alkyl group C _n H _{2n + 1} of bis (alkylphenyl) iodonium hexafluorophosphate was 10 to 14. Moreover, the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of single terminal-TEMPO polytetrahydrofuran are Mn = 1,720 and Mw / Mn = 1.91 respectively in terms of standard polymethyl methacrylate. there were. The above mixture was degassed and sealed, and irradiated with light at a room temperature using a 500 W ultra high pressure mercury lamp (manufactured by Wacom) at an output of 7.0 A for 6 hours. Thereafter, the container was opened, and 10 mL of methylene chloride was added to completely dissolve the solidified product. This methylene chloride solution was added dropwise to 500 mL of hexane, and the resulting block copolymer was isolated. The block copolymer was purified by repeated reprecipitation from methylene chloride solution into hexane. The obtained block copolymer was dried under reduced pressure, and then freeze-dried using benzene, to finally obtain 472 mg of a polymethyl methacrylate-block-polytetrahydrofuran diblock copolymer. The number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of the obtained diblock copolymer were Mn = 21,800 and Mw / Mn = 1.85, respectively, in terms of standard polymethyl methacrylate. It was. 1H-NMR measurement was performed on the obtained diblock copolymer using a 300 FT-NMR apparatus (manufactured by Varian). The obtained 1H-NMR spectrum is shown in FIGS. 1A and 1B. The letters attached to the spectral peaks in FIGS. 1A and 1B correspond to the letters attached to the structural formula in FIG. 1C, respectively.

The one-terminal-TEMPO-modified polytetrahydrofuran as the polymer mediator was synthesized as follows.
<Method for synthesizing one terminal-TEMPO-modified polytetrahydrofuran>
To a solution of 1.69 g of 4-hydroxy-TEMPO dissolved in 11 mL of THF, 352 mg of sodium hydride was added at room temperature, the mixture was stirred at room temperature for 2 hours, and a suspension of 4-sodiumoxy-TEMPO was added. Prepared. To 100 mL of THF distilled from sodium, 0.37 mL of methyl trifluoromethanesulfonate was added at room temperature and stirred at room temperature for 7 minutes, and then a suspension of 4-sodiumoxy-TEMPO was added to this solution at 0 ° C. The mixture was stirred at 0 ° C. for 5 minutes and further stirred at room temperature for 55 minutes. Thereafter, 1 mL of water was added to the mixture. Unreacted THF was removed by an evaporator, and the residue was dissolved in 500 mL of hexane. This hexane solution was washed with water and dried over anhydrous magnesium sulfate. After the magnesium sulfate was filtered off, hexane was removed by an evaporator, and the product was vacuum-dried at 50 ° C. for several hours to obtain 1.53 g of one-end-TEMPO polytetrahydrofuran.
(Example 2)

To 1 mL of methyl methacrylate monomer purified as in Example 1, 7 mg of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) as a radical polymerization initiator and as a photoacid generator 19 mg of a 50 wt% propylene carbonate solution of bis (alkylphenyl) iodonium hexafluorophosphate and 134 mg of one-end-TEMPO-modified polytetrahydrofuran as a polymer mediator were dissolved.
Here, the carbon number n of the alkyl group C _n H _{2n + 1} of bis (alkylphenyl) iodonium hexafluorophosphate was 10 to 14. In addition, the number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of single-end-TEMPO-modified polytetrahydrofuran are Mn = 12,700 and Mw / Mn = 1.25, respectively, in terms of standard polymethyl methacrylate. there were.
The mixture was degassed and sealed, and irradiated with light for 6 hours in the same manner as in Example 1. Thereafter, the container was opened, and 10 mL of methylene chloride was added to completely dissolve the solidified product. This methylene chloride solution was added dropwise to 500 mL of hexane, and the resulting block copolymer was isolated. The block copolymer was purified by repeating reprecipitation from a methylene chloride solution into hexane, and then dried under reduced pressure, followed by freeze-drying, and finally 663 mg of polymethyl methacrylate-block-polytetrahydrofuran. The diblock copolymer was obtained. The number average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of this diblock copolymer were Mn = 32,300 and Mw / Mn = 3.64, respectively, in terms of standard polymethyl methacrylate.

The one-terminal-TEMPO-modified polytetrahydrofuran as the polymer mediator was synthesized as follows.
<Method for synthesizing one terminal-TEMPO-modified polytetrahydrofuran>
To a solution of 1.69 g of 4-hydroxy-TEMPO dissolved in 11 mL of THF, 352 mg of sodium hydride was added at room temperature, the mixture was stirred at room temperature for 2 hours, and a suspension of 4-sodiumoxy-TEMPO was added. Prepared. To 100 mL of THF distilled from sodium, 0.37 mL of methyl trifluoromethanesulfonate was added at room temperature and stirred at room temperature for 30 minutes. A suspension of 4-sodiumoxy-TEMPO was added to this solution at 0 ° C. The mixture was stirred at 0 ° C. for 5 minutes and further stirred at room temperature for 55 minutes. Thereafter, 1 mL of water was added to the mixture. Unreacted THF was removed by an evaporator, and the residue was dissolved in 500 mL of hexane. This hexane solution was washed with water and dried over anhydrous magnesium sulfate. After the magnesium sulfate was filtered off, hexane was removed by an evaporator, and the product was vacuum-dried at 50 ° C. for several hours to obtain 20.6 g of one-end-TEMPO polytetrahydrofuran.

<Molecular weight measurement by GPC>
The molecular weight of the block copolymer was measured by GPC (gel permeation chromatography) under the following conditions.
・ Device: GPC-8020 (manufactured by Tosoh Corporation)
Column: TSK G2000HXL, G4000HXL and G6000HXL (manufactured by Tosoh)
・ Temperature: 40 ℃
・ Solvent: THF (tetrahydrofuran)
・ Flow rate: 1.0 mL / min ・ Sample: 1 mL injection of a sample with a concentration of 0.5% Molecular weight calibration curve created from a monodisperse polymethyl methacrylate standard sample from the molecular weight distribution of the block copolymer measured under the above conditions Was used as the number average molecular weight Mn and the weight average molecular weight Mw of the block copolymer.

  The block copolymer of the present invention comprises various surfactants, a compatibilizing agent for mixing different polymers, a fiber surface modifier, a coating and dye dispersion stabilizer, a building cement dispersant, a drug transporter. It can be suitably used as a drug carrier of the system.

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Claims (4)

A method for producing a block copolymer having a repeating unit of a first monomer and a repeating unit of a second monomer,
Photoliving radical polymerization of the second monomer in the presence of a compound having 2,2,6,6-tetramethylpiperidine-1-oxyl at the terminal of the repeating unit of the first monomer. A method for producing a block copolymer, comprising producing a block copolymer.   The method for producing a block copolymer according to claim 1, wherein the photo-living radical polymerization is initiated by a radical polymerization initiator and is carried out in the presence of a photo-acid generator. The method for producing a block copolymer according to claim 2, wherein the repeating unit of the second monomer is represented by the following general formula (2).
In general formula (2), R ¹ represents a radical polymerization initiator residue, and R ² represents an alkyl group. The alkyl group may contain at least one of a perfluoroalkyl group, a hydroxy group, an amino group, and a glycidyl group. n represents an arbitrary positive number.   A block copolymer produced by the method for producing a block copolymer according to claim 1.