JPH07196809A - Silicon polymer - Google Patents

Abstract

PURPOSE:To obtain a silicon polymer with a high thermal stability and a low m.p. by subjecting a specific silaindan compd. to ring-opening polymn. using an anionic initiator. CONSTITUTION:A silaindan compd. of the formula (wherein Ph is a phenyl group; and R is and alkyl group) is subjected to ring opening polymn. using an anionic initiator, thus giving a silicon polymer comprising repeating units each represented by -Si(Ph)(R)-CH2-0-C6H4-CH2- (wherein Ph and R are each the same as described above).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon-based polymer having good thermal stability and a low melting point due to a decrease in symmetry of the main chain, and a method for producing the same.

[0002]

2. Description of the Related Art At present, various types of silicon-based materials have been synthesized according to their characteristics and required performance. Polysilane, polycarbosilane, polysiloxane, and polysilazane are the main skeletons of silicon-based materials,
The practical use of polycarbosilane is only utilized as a precursor of silicon carbide ceramics, and the structure thereof has not been clearly identified. Therefore, almost no synthesis of polycarbosilane having various structures has been performed.

In the synthetic method by ring-opening polymerization, various polymers have been reported so far, and among them, disclosed by Weber et al. [-SiMe ₂ -CH _{2-].
o-C 6 H 4 -CH 2} -] , but it is a good thermal stability,
High melting point (William P Weber et al. (Will
iam P. Weber et al. ):polymer·
Burchin (Polymer Bulletin), 2
2,349 (1989)), it was a problem that it was inferior in moldability when used in various forms such as coatings, films, fibers, and bulk bodies, and when used with a so-called composite matrix resin. .

[0004]

DISCLOSURE OF THE INVENTION The present invention is to develop a material and a method for solving these problems as a result of earnest research in view of such actual circumstances. An object of the present invention is to provide a silicon-based polymer having excellent thermal stability and a low melting point, and a method for producing the same.

[0005]

The above objects of the present invention have been achieved by the following means. That is, the formula −Si (P
_{h) (R) -CH 2 -o} -C 6 H 4 -CH 2 - ( wherein,
Ph is a phenyl group, R is an alkyl group, and is composed of a repeating unit represented by the following formula: a silicon-based polymer having an ordered structure; ) represented by the Shiraindan ring compound monomers, by ring-opening polymerization using an anionic initiator, wherein -Si (Ph) (R) -CH 2 -o-
A method for producing a silicon-based polymer, which obtains a polymer composed of repeating units represented by C ₆ H ₄ —CH ₂ — (wherein Ph represents a phenyl group and R represents an alkyl group),

[0006]

[Chemical 2] Is.

The present invention will be described in detail below. The silicon-based polymer synthesized in the present invention is synthesized by ring-opening polymerization of a silaine dan ring compound represented by the following formula as a monomer. The monomer may be used alone or in combination of two or more.

[0008]

[Chemical 3]

In the formula, R is a monovalent organic group having 1 to 20 carbon atoms or a monovalent functional group, and the organic group may contain a functional group. R is, for example, methyl,
Ethyl, n-propyl, i-propyl, n-butyl, t
-Butyl, isoamyl, n-octyl, n-nonyl, phenyl, chloro group and the like. Ph is a phenyl group.

In the polymerization method, the monomer and the initiator are used, but the solvent may or may not be used. Further, a stabilizer for the anion to be generated may or may not be used. The reaction temperature is preferably 30 ° C to -100 ° C, more preferably 0 ° C to -80 ° C.

Examples of the initiator used for the polymerization include a compound represented by RLi as an anionic initiator, or a solution thereof. R is a monovalent organic group having 1 to 20 carbon atoms, and the organic group may include a functional group. Further, it may be a compound represented by the formula (R ₃ ) SiK or a solution thereof. In the formula, R is 1 having 1 to 20 carbon atoms.
Valent organic groups or functional groups, which may be the same or different. Further, the organic group may contain a functional group. Further, it may be a compound represented by the formula (R ₄ ) NF or a solution thereof. In the formula, R is a monovalent organic group having 1 to 20 carbon atoms or a functional group, which may be the same or different, and the organic group may contain a functional group.

The amount of the initiator used is not particularly limited, but it is preferable to use it in the range of 1 to 0.01 mol, more preferably 0.5 to 0.0, per 1 mol of the monomer.
It is preferable to use it in the range of 5 mol.

Specific examples of the solvent used for the polymerization include hydrocarbon solvents such as benzene and toluene, ether solvents such as tetrahydrofuran, 1,4-dioxane and diethyl ether, chloroform, methylene chloride,
A halogen-based solvent such as 1,2-dichloroethane can be used. From the viewpoint of anion stability, ether solvents are preferable, and tetrohydrofuran is more preferable.

The amount is not particularly limited, but it is preferably used in the range of 0 to 5 L, and more preferably 0.5 to 2 L, relative to 1 mol of the monomer. A polar compound is preferably used as the anion stabilizer, and hexaphosphoric amide is preferable. The amount of the stabilizer used is not particularly limited,
It is preferable to use it in the range of 0 to 5 mol, preferably 0.5 to 2 mol, relative to 1 mol of the initiator.

[0015]

EXAMPLES The present invention will be specifically described below with reference to examples, but the contents of the present invention are not limited thereto. Example Under a nitrogen atmosphere, 2 mL of tetrahydrofuran (THF) distilled from metal Na immediately before was added as a solvent to 224 mg (1 mol) of 2-methyl-2-phenyl-2-silynedan, and further hexaphosphoric triamide 1 was added.
7.9 mg (0.1 mmol) was added and it cooled at -78 degreeC. 125 μL (1.6N, n-BuLi hexane solution as an initiator)
0.2 mmol) was added. The system turned yellow with the addition of the initiator. After 3 hours, 1 mL of a saturated aqueous NH ₄ Cl solution was added as a terminating agent, and the mixture was left to stand until it reached room temperature. THF
The layer was washed with ion-exchanged water, the organic layer was dried over anhydrous MgSO ₄ , and the solvent was distilled off to obtain a crude polymer.
The crude polymer was purified by reprecipitation from CHCl ₃ / MeOH, dried under reduced pressure and then of the formula —Si (Ph) (Me) —CH.
To obtain a polymer 75.8mg having a repeating unit structure of _{- 2 -o-C 6 H 4} -CH 2. Yield: 32%. The number average molecular weight was 8100 and the weight average molecular weight was 18500 as measured by relative molecular weight (GPC) with respect to a polystyrene standard by a refractive index detector. The thermal weight loss rate under a nitrogen atmosphere was 6.8% at 400 ° C and 22% at 500 ° C. The melting point was 55 to 61 ° C. Comparative Example Under nitrogen atmosphere, 2,2-dimethyl-2-silaidane 1.62 g (10 mol) was added with THF 2 mL distilled from metallic Na immediately before as a solvent, and further hexaphosphoric triamide 89.5 mg (0.5 mmol) was added and the mixture was cooled to -78 ° C. 1.2 mL (1.6 N, 2 mmol) of n-BuLi hexane solution was added as an initiator. The system turned brown with the addition of the initiator. After 3 hours, 1 mL of a saturated aqueous NH ₄ Cl solution was added as a terminating agent, and the mixture was left to stand until it reached room temperature. The THF layer was washed with ion-exchanged water, the organic layer was dried over anhydrous MgSO ₄ , and the solvent was distilled off to obtain a crude polymer. The crude polymer was added to CHCl ₃ / M
Purified by reprecipitation from OH, dried under reduced pressure, and then of the formula-Si
_{Me 2 -CH 2 -o-C 6} H 4 -CH 2 - to give a polymer 471mg having the repeating unit structure. Yield: 29
%. The number average molecular weight measured by GPC was 14,800, and the weight average molecular weight was 6,500. The thermal weight loss rate in a nitrogen atmosphere is 2.3% at 400 ° C and 12.6 at 500 ° C.
%Met. The melting point was 159 to 162 ° C.

[0016]

According to the present invention, a silicon polymer having good thermal stability and a low melting point was obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshifumi Hirose 7-2-3 Kaminomiya, Suma-ku, Hyogo Prefecture

Claims (2)

[Claims] 1. The formula —Si (Ph) (R) —CH ₂ —o—
C ₆ H ₄ -CH ₂ - (wherein, Ph represents a phenyl group, R represents an alkyl group) silicon-based polymer composed of repeating units represented by. 2. The following formula (wherein Ph is a phenyl group and R is
Is represented by an alkyl group), a Shiraindan ring compound monomers, by ring-opening polymerization using an anionic initiator, wherein -Si (Ph) (R) -CH 2 -
_{o-C 6 H 4 -CH 2} - ( wherein, Ph represents a phenyl radical, R
Represents an alkyl group), and a polymer composed of repeating units represented by [Chemical 1]