JPS58201809A - Novel polystyrene - Google Patents

Abstract

PURPOSE:A novel polystyrene useful as a standard substance for measuring molecular weight, polymer for resist, etc., shown by a specific structural formula, having the same end group structures, symmetry, and a narrow molecular weight distribution. CONSTITUTION:Styrene is subjected to living polymerization using a tertiary amine coordinated benzyl metal compound [e.g., N,N,N',N'-tetraalkyldiamine shown by the formula I (R1-R4 are 1-10C alkyl; R' is 1-10C alkylene) as the tertiary amine, etc., and lithium, sodium, etc. as the metal, etc.] as an initiator in a solvent such as toluene, etc. preferably at -20-70 deg.C, to give the desired polystyrene having a plane of symmetry in a molecular chain shown by the formula II (n>=1).

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a novel polystyrene having a plane of symmetry in its molecular chain and a method for producing the same.

As is well known, polystyrene and its derivatives are used in biochemical products such as proteins and polysaccharides, as well as plastics.

It can be used to measure the molecular weight of synthetic polymers such as rubber and fibers, and is widely used as a standard material for GPO (gel permeation chromatography) and light scattering photometers. In recent years, polystyrene and its derivatives have also attracted attention as polymers for resists that can be plasma etched.

! - However, in this variety of applications, there are disadvantages or problems below that of conventional polystyrene KFi. That is, (1) because the polymerization initiation reaction of conventional polystyrene is carried out with alkyl lithium (e.g., butyl lithium), etc., an alkyl group (e.g., butyl group) as an initiator is added to one end of the obtained polystyrene; Therefore, when such polystyrene is used for molecular weight measurement, the influence of such terminal groups cannot be ignored, especially for low molecular weight polystyrene. In other words, it will affect the accuracy of analysis.

(2) As polystyrene for resists, polystyrene with a narrow molecular weight distribution is necessary to improve the resolution of resists, but it is difficult to meet these requirements with polystyrene obtained by conventional polymerization methods.

As a result of various studies on the polymerization reaction of styrene, the present inventors found that the above (1) of conventional polystyrene was obtained.

We have discovered a new polystyrene and a method for producing the same that solves the drawback or problem (2), and have arrived at the present invention.

Ji! The present invention relates to a novel polystyrene having a plane of symmetry in its molecular chain and having a narrow molecular weight distribution represented by the following general formula.

(However, n≧1) Polystyrene having the same terminal structure and symmetry represented by the above general formula of the present invention can be produced by living polymerization of styrene in a solvent using a tertiary amine-coordinating benzyl metal compound as an initiator. It is obtained by

The reason why polystyrene with such symmetry and a soft molecular weight distribution can be obtained in the present invention is because living polymerization, in which termination reactions and chain transfer reactions do not occur during polymerization, is used, and the polymerization initiation rate of the father and the initiator is increased. This is considered to be because the depolymerization reaction rate is sufficiently large compared to the depolymerization reaction rate and sufficiently low.

That is, it is thought that this is because the initiation rate of 6th class amines, especially 5th class diamine-coordinated benzyl alkali metals, etc. is sufficiently higher than the polymerization rate of styrene, and depolymerization of polystyrene hardly occurs.

As the tertiary amine constituting a part of the tertiary amine-coordinated benzyl metal compound which is the initiator used in the polymerization reaction of the present invention, a compound having two or more tertiary amino groups is suitable. An example is as follows.

N, N, N', N'- shown by the following general formula
Tetraalkyl diamine R1-R11; alkyl (01-0□.)R'
i Alkylene (0, ~01o) Compound represented by the following general formula -3 = nl; 2-8 n2; 2-8 Compound represented by the following general formula nH1-5 nJ1-5 Pyridine derivative represented by the following formula (-)-3 Obtained as a natural product like Subartein
2,3-dimethoxy derived from tartaric acid
1,4-bis(dimethylamino)butane, hexamethylphosphortriamide, crown ether, etc.

The metal constituting a part of the initiator used in the polymerization reaction of the present invention may be any metal that is generally used in anionic polymerization. For example, alkali metals and alkaline earth metals.

4- Aluminum and similar metals are mentioned, with lithium and sodium being preferred.

The polystyrene of the present invention can be obtained, for example, by adding a styrene monomer to a solution of the above-mentioned 6-class amine-coordinated benzyllithium and polymerizing it, or by adding a 6-class amine-coordinated benzyllithium solution to a solution of the styrene monomer. In addition, polymerization may be performed.

In this case, the amount of the tertiary amine-coordinated benzyllithium can be adjusted to suit the desired molecular weight of the polystyrene.

Note that benzyllithium is produced almost quantitatively in the reaction of toluene and butyllithium in the presence of a tertiary amine, so
When polymerizing in toluene, there is no need to specifically synthesize benzyllithium, and tertiary amine and butyllithium may be used.

In the polymerization reaction of the present invention, any polymerization solvent may be used as long as it does not inhibit the hariping polymerization. Preferred are hexane, toluene, penzene, tetrahydrofuran, a toluene-tetrahydrofuran mixture, and particularly preferred is toluene. It is.

The polymerization temperature is preferably -78°C to 100°C, particularly preferably -20°C to 70°C.

Polymerization method 4-m for obtaining monodisperse polystyrene with a narrow molecular weight distribution of the present invention In IJ ping polymerization, in order to prevent the molecular weight distribution from becoming wide, it is necessary to use water that easily reacts with the growing ends.

Care must be taken to avoid contamination with impurities such as oxygen, carbon dioxide, and proton donors. Specifically, the final purification equipment and polymerization equipment for various reagents such as styrene, solvents, and initiators are degassed to a high vacuum, and the polymerization is carried out by making the gas solution as dilute as possible and stirring it to make the monomer homogeneous and to mix it with the initiator. It is desirable to mix the monomers rapidly and allow them to react until the polymerization is complete. It is desirable to terminate the polymerization using an alcohol such as methanol.

According to the polymerization method of the present invention, polystyrene with a narrow polymerization degree distribution and the following degree of dispersion can be obtained.

General formula % formula % However, 2 is the number average molecular weight, and 2 is the weight average molecular weight.
Number average and weight average molecules in ζ/tag - 1 tu initiator fragments are excluded.

The polystyrene obtained by the polymerization method of the present invention, which has a narrow polymerization degree distribution, the same terminal structure on both ends, and is symmetrical can be advantageously used as a VC for various purposes such as a standard substance for molecular weight measurement, and a polymer for resists.

Next, the present invention will be explained with reference to Examples, but the present invention is not limited thereto.

In the examples, the solvent and styrene used were those purified as follows.

Polymerization solvent: Toluene was purified by a conventional method, and then vacuum distilled in the presence of butyllithium.

Styrene: C after being purified by conventional methods! The mixture was mixed with aH2 and vacuum distilled.

Example 1 Polymerizations were carried out under dry nitrogen in a well-dried glass reactor. Butyl lithium (4,6
mmole, hexane solution) and (-)-sparteine (5.5 mmole) were added at room temperature, and after 30 minutes it was cooled to 0°C. Add to this styrene C0,929°9.2mmo
le) was added and polymerized. After 1 hour, the reaction was stopped with a small amount of methanol, and the reaction solution was diluted with diluted hydrochloric acid.

After washing with water, it was dried with magnesium sulfate.

When the solvent was distilled off, a viscous liquid was obtained in a yield of 98 cm.

The 100 MH21H nuclear magnetic resonance spectrum of this polystyrene is shown in FIG. (Solvent Cat, , reference material TM8. Measurement temperature 35°C) This spectrum Lrl I
There is no peak derived from butyl groups near ppm, indicating that there are many butyl groups at the polymerization terminals.

Furthermore, a column packed with silica gel treated with diphenyldichlorosilane (length 25 Crn x inner diameter 0.46 on)
) and high-performance liquid chromatography to analyze the polymer (
The distribution of oligomers) was measured.

Average degree of polymerization fJ determined from peak height n=2.06
The molecular weight distribution was ζ/Mnf11,19. The chromatograph is shown in FIG.

From a comparison of the ratio of the methine and methylene protons in the main chain to the benzene ring protons in the nuclear magnetic resonance spectra of FIG. 2 and FIG. 1, it was confirmed that it was polystyrene with a benzyl group at the polymerization end.

Example 2 In the same manner as in Example 1, (-)- was used as a tertiary diamine.
N,N,N',N'-tetramethylethylenecyamine was used instead of sparteine, and 150%
Polymerization was also carried out using mol of butyllithium. The resulting reaction mixture was precipitated with methanol to which a small amount of hydrochloric acid had been added, separated from F, washed, and dried.

When the GPO (Kölpermeation chromatography) of the polystyrene obtained in a yield of 97 minutes was measured, the average degree of polymerization was n = 52 r MwAζ = 1.05.

[Brief explanation of the drawing]

FIG. 1 is a nuclear magnetic resonance spectrum of an example of the polystyrene of the present invention, and FIG. 2 is a diagram showing its high performance liquid chromatography. Applicant's agent Kaoru Furuya

Claims (1)

[Claims] Polystyrene represented by the following general formula (however, n≧
1)