JPH08100026A - Change in propagating terminal of living polymer and production of block copolymer - Google Patents

Abstract

PURPOSE: To provide a method for changing the propagating terminal of a living polymer by using a specified compound, whereby the control of polymer properties can be effected quantitatively under gentle conditions and the application of the polymer as a mechanical material can be broadened. CONSTITUTION: The polarity of the propagating terminal of a living polymer is changed by using a rare earth metal compound or complex. A representative example of the rare earth metal is samarium, and representative examples of the compounds include halides and alcoholates. A polymerization reaction is performed by using the living polymer having a changed polarity as the initiator to obtain a block copolymer containing the living polymer as a structural unit. For example, a block copolymer of a cationically polymerizable monomer such as tetrahydrofuran, aziridine, oxazoline or a vinyl ether with an anionically polymerizable monomer such as styrene, a methacrylic ester, methacrylamide a lactone or a cyclic siloxane can be obtained. It is also possible to introduce a nucleophilic reagent into the terminal of the polymer having a changed polarity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for converting a growing end of a living polymer and a method for producing a block copolymer. More specifically, the present invention relates to a novel method for changing the polarity of a growing terminal capable of controlling polymer physical properties and expanding its application as a functional material, and a block copolymer using this method. The present invention relates to a manufacturing method.

[0002]

2. Description of the Related Art Conventionally, various polymers and block copolymers have been utilized in various fields.
In recent years, sophistication of its characteristics and high functionality have been attempted. However, the technologies up to now still have serious limitations, and many challenges remain for technological innovation in polymer materials. For example, although a block copolymer is a useful polymer whose application has been realized in the field of thermoplastic rubber and the like, the kinds of monomers that can be used here are greatly restricted. While it can be expected that polarity conversion of the growing end will greatly improve these restrictions, the conventional growing end conversion method requires not only multiple steps and some complicated operations, but also quantitative conversion. Very few examples have achieved efficiency. Therefore, it is considered that a homopolymer composed of only one monomer is likely to be mixed in the obtained block copolymer, and it is impossible to sufficiently exhibit the function of the block copolymer.

With respect to these block copolymers, since controlling the active end of the unit unit itself is important, it is desired to control the growing end of the unit unit. However, the actual situation is that effective means have not yet been found for this problem.
Therefore, the present invention aims to provide a new technical means that makes the control of the polymer growing end more effective and can utilize the control in the production of the block copolymer. There is.

[0004]

In order to solve the above-mentioned problems, the present invention is characterized in that the growing end of a living polymer is converted into a polarity by a compound or complex of a rare earth metal. A method (claim) is provided. Further, the present invention is a method for producing a block copolymer, characterized in that a polymerization reaction is carried out using a living polymer whose polarity is converted by the above method as an initiator to produce a copolymer containing the living polymer as a constituent unit. (Claim 5) is provided.

In the present invention, in the above conversion method, the polarity is converted by the reaction with the electrophile (claim 2).
In particular, the polarity is converted by a divalent samarium (Sm) compound or complex (Claim 3), and further, the polarity of the growing terminal of tetrahydrofuran (THF) is converted (Claim 4). This is also the case.

[0006]

The above-described method of the present invention was made on the basis of the recognition of the above-mentioned problems relating to polymers and block copolymers, and the clue at that time was the rare earth metal. It is a new finding on the reaction activity of the compound of 1) and its complex.

That is, in recent years, many studies on the basic physical properties and reactivity of rare earth complexes and their application to organic synthesis have been reported, and the full range of their characteristics is being clarified. In particular, divalent and tetravalent rare earth compounds or complexes have been widely used in organic synthesis, particularly natural product synthesis, etc., as excellent reducing agents and oxidizing agents, respectively. Applications to material science are still limited. In this situation,
The present invention utilizes the ability of the rare earth compound and its complex as an excellent one-electron reducing agent and oxidizing agent to carry out polarity conversion of the polymer growth terminal in one pot. According to the present invention, the conversion of the growing terminal can be achieved quantitatively and under mild conditions, and by applying this, various types of block copolymers which are difficult to synthesize by conventional methods, for example, tetrahydrofuran, aziridine, A block copolymer of a cation-polymerizable monomer such as oxazoline and vinyl ether and an anion-polymerizable monomer such as styrene, methacrylic acid ester, methacrylic acid amide, lactone and cyclic siloxane can be easily synthesized.

Further, by appropriately selecting the reaction conditions and the polymerization system, the molecular weight, composition ratio and the like can be easily controlled, and it becomes possible to design and synthesize an arbitrary block copolymer. A typical rare earth metal is samarium (Sm), but the rare earth metal is not limited to this. Further, as the compound, any compound such as halide and alcoholate can be used, and the kind of the ligand for the complex can be appropriately selected.

Examples will be more specifically described below, and the conversion method and the method for producing a block copolymer of the present invention will be described in more detail.

[0010]

Example 1 THF (tetrahydrofuran) is known to undergo cationic ring-opening polymerization with a suitable initiator to give a living polymer, and this growing end reacts efficiently with various nucleophiles. ing. Therefore, in this embodiment, poly (T
The growing end of (HF) was reduced with samarium iodide, which is a one-electron reducing agent. As a result, the conversion to anionic species proceeded efficiently, and various electrophiles were successfully introduced into the polymer terminals.

The reaction was carried out according to the following equation.

[0012]

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That is, THF was polymerized using methyl trifluoromethanesulfonate. The reduction reaction was performed by adding a THF solution of HMPA and SmI _{2 to} a living poly (THF) solution and stirring the mixture at room temperature for 30 minutes.
The polymer obtained by post-treatment with acid has no hydroxyl group at the end of the polymer and is quantitatively reduced by two-electron (2)
Obtained. At this time, side reactions such as disproportionation and dimerization did not occur at all. Two-electron reduced poly (THF)
As a result of attempting the reaction of (1) with various electrophiles, when aldehydes, ketones, and isocyanates were used, Table 1
As described above, the electrophile could be introduced almost quantitatively at the polymer terminal.

[0014]

[Table 1]

Example 2 When the cation species at the growing end of poly (tetrahydrofuran) were reduced by utilizing the reducing ability of the samarium complex, two-electron reduction proceeded rapidly, and t-butylmethacrylate produced by the anion species produced. It was confirmed that the block copolymer of THF-TBMA was obtained by the polymerization of lat (TBMA).

That is, according to the following formula, first, THF is cationically polymerized by using methyl triflate as an initiator, and then a solution of 2 equivalents of samarium iodide in THF to HMPA and methyl triflate is added to the solution to reduce the growth terminal. Was done. Next, when the polymerization of TBMA with the terminal anions of the produced poly (THF) was examined, anionic polymerization proceeded, and as shown in Table 2, monodispersed THF was used.
A block copolymer of TBMA could be obtained.

[0017]

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[0018]

[Table 2]

FIG. 1 shows entry 3 (Mn = 9) of Table 2.
600) ¹ H-NMR spectrum (60 ° C., CDCl
₃ ) is shown. Example 3 THF polymerization was carried out using trifluoromethanesulfonic anhydride, which is a bifunctional initiator, and samarium (I
When the growing end was reduced by I) and TBMA was polymerized by the generated anion species, a monodisperse block copolymer of TBMA-THF-TBMA was obtained.

That is, first, THF was polymerized for 5 minutes at room temperature using trifluoromethanesulfonic anhydride, and then HMPA and 4 equivalents of a samarium iodide THF solution with respect to trifluoromethanesulfonic anhydride were added to this solution. , Reduction of the growing end was performed. At this time, poly T
Homo-coupling among HFs and side reactions such as disproportionation did not proceed at all.

Next, when TBMA was polymerized with both terminal anions of the produced polyTHF, it was found that anionic polymerization proceeded and a monodisperse TBMA-THF-TBMA block copolymer was obtained. The molecular weight distribution of the obtained block copolymer was almost the same as that of polyTHF, and the polymerization proceeded while maintaining the narrow molecular weight distribution. Further, in the GPC measurement, the peak derived from the homopolymer of polyTHF was completely disappeared, which confirmed that the block copolymerization proceeded almost quantitatively according to the following equation.

[0022]

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[0023]Example 4 Under a nitrogen stream, trifluoromethanesulfonic anhydride (1
7 mg) to THF (5 mL) and stirred at room temperature for 5 minutes
Was. HMPA (180 mL), 0.1M in this polymerization solution
THF solution of samarium iodide (2.4 mL) was added,
The mixture was stirred at room temperature for about 30 minutes. Then TBMA (648m
g) and stir at room temperature for 24 hours.
ABA type birds of TBMA and THF
The block copolymer was isolated. (688 mg, molecular weight 2
0000, molecular weight distribution 1.03) Example 5 Under a nitrogen stream, trifluoromethanesulfonic anhydride (2
9 mg) was added to THF (5 mL) and stirred at room temperature for 5 minutes.
Was. HMPA (300 mL), 0.1M in this polymerization solution
THF solution (4 mL) of samarium iodide was added to room temperature.
The mixture was stirred for about 30 minutes. Then ε-caprolactone (2
82 mg) and stirred at 0 ° C. for 3 hours.
The block between THF and ε-caprolactone was extracted by ruene extraction.
The lock copolymer was isolated. (355 mg, molecular weight 54
00, molecular weight distribution 1.21)

[0024]

As described above in detail, according to the present invention, the technology relating to polymers and block copolymers is newly developed, and industrially useful block copolymers and the like can be provided. More specifically, for example, since the block copolymer of THF and TBMA obtained in the Examples is composed of a THF unit which is a soft segment and a polyTBMA which is a relatively hard segment, a novel thermoplastic Application as rubber can be expected. Further, in the present invention, since various functional groups can be easily introduced into the methacrylic acid esters, various properties such as thermal stability and liquid crystallinity can be added to the block copolymer.
It is also possible to endow physiological activity and the like. Furthermore, the properties of the resulting block copolymer can be significantly changed only by changing the combination of the monomers used.

[Brief description of drawings]

FIG. 1 is a ¹ H-NMR spectrum diagram as an example.

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[Procedure amendment]

[Submission date] October 3, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

In the present invention, in the above-mentioned conversion method, the reaction between the polar-converted polymer terminal and the electrophile is carried out.
(Claim 2), in particular, the polarity is converted by a compound or complex of divalent samarium (Sm) (Claim 3), and further, the polarity of the growing terminal of tetrahydrofuran (THF) is converted (Claim 4). ) And the like are also used as its mode.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

Next, when TBMA was polymerized with both terminal anions of the produced polyTHF, it was found that anionic polymerization proceeded and a monodisperse TBMA-THF-TBMA block copolymer was obtained. The molecular weight distribution of the obtained block copolymer was almost the same as that of polyTHF, and the polymerization proceeded while maintaining the narrow molecular weight distribution. In addition, since the peak derived from the homopolymer of polyTHF had completely disappeared in the GPC measurement, block copolymerization started almost quantitatively according to the following equation.
It was confirmed that it was done.

Claims (5)

[Claims] 1. A method for converting a growing end of a living polymer, wherein the growing end of the living polymer is converted into a polarity by a compound or complex of a rare earth metal. 2. The method according to claim 1, wherein the polarity is converted by reaction with an electrophile. 3. The method according to claim 1, wherein the polarity is converted by a divalent samarium compound or complex. 4. The method of claim 1, 2 or 3 wherein the growing end of the tetrahydrofuran living polymer is converted. 5. A block copolymer comprising a living polymer whose polarity is converted by the method according to claim 1 as an initiator to produce a copolymer containing the living polymer as a constituent unit. Production method.