KR970009240B1 - Method for block copolymer of alkylene oxide with vinyl or diene monomers by anionic polymerization - Google Patents

Abstract

The invention produce a block copolymer useful as a stabilizer anion comprising polymerizing alkyleneoxide and vinyl or diene monomer in the presence of nonpolar solvent. After living polymerizing vinyl monomer or diene monomer using alkyl lithium such as n-butyl lithium as a initiation agent in the presence of nonpolar solvent which is benzene, toluene etc., then adding a mole ratio of 10-0.5 of mixtures of alkali metal alkoxide to alkyl lithium, then effect a block copolymerization in 50-70 deg. C by continuing adding a epoxide monomer.

Description

Block copolymerization method of alkylene oxide and vinyl or diene monomer by anionic polymerization

The present invention relates to a process for producing block copolymers of alkylene oxides and vinyl or diene multimers in nonpolar solvents by anionic polymerization.

Conventionally, polymerization of polyalkylene oxides has been generally carried out by an anionic polymerization reaction using an alkali metal alkoxide initiator and using tetrahydrofuran (THF) or Diglyme as a solvent [Journal of Polymer Science: Part A: Polymer chemistry, Vol. 26, p. 2031]. Another synthetic method is to prepare dimethyl sulfide by reacting dimethyl sulfoxide (DMSO) with potassium tert-butoxide, and then pressurize ethylene oxide in DMSO [Journal of Polymer Science: Part A-1, agent 7, pp. 569].

In such a conventional polymerization method, a polar solvent must be used, and the polar solvent used is highly toxic and causes various safety problems. In addition, due to the use of a polar solvent, not only takes a lot of time in the purification process of the polyalkylene oxide and the block copolymer including the same after the preparation of the polymer, there is a disadvantage that the purification process itself is very difficult.

On the other hand, a method of anionic polymerization of vinyl-based and diene-based monomers using alkyllithium as an initiator is known [Advanced in Polymer Science, Vol. 56, page 1]. However, when using this polymerization method, it is known that it is practically impossible to prepare an epoxide polymer and a block copolymer containing the same using alkyllithium as an initiator even if THF, a polar solvent as well as a polar solvent, is used. Opening Polymerization, ACS Symposium series, No. See pages 286, 37].

As a colloidal stabilizer, a copolymer having a block form of a hydrophilic polymer and a hydrophobic polymer is widely used. For example, a block copolymer of a hydrophilic polymer polyalkylene oxide and a hydrophobic polymer vinyl or diene polymer is known to be particularly useful as a stabilizer.

However, conventionally, block copolymers of vinyl or diene monomers and epoxide monomers have been prepared through a number of reaction and purification steps. That is, after living polymerization of a styrene or diene monomer with alkyllithium as an initiator, and then quenched with ethylene oxide, and reacted with an acid to produce an alcohol having a hydroxy (-OH) group at the end of the chain. These block copolymers are prepared by precipitating the polymer in a low-cost alcohol such as methanol, drying it, reacting with sodium hydroxide or potassium hydroxide, and then adding ethylene oxide monomer again in a polar solvent such as THF. [Advanced in Polymer Science , Vol. 56, pp. 1 to 90].

Moreover, it is known that when copolymerizing alkyllithium with a non-polar solvent, a block copolymer of vinyl polymer and epoxide polymer cannot be prepared by monomer addition method in a single reactor [Die Makromolecular Chemie, Macromolecular Symposium, 42, 43, pages 463-473].

It is therefore an object of the present invention to provide a process for the anionic polymerization of various block copolymers comprising polyalkylene oxides which makes it possible to use nonpolar solvents which do not cause toxicity and purification problems.

Another object of the present invention is to provide a method for the anionic polymerization of polyalkylene oxide which can easily adjust the molecular weight which was not possible due to various side reactions in the conventional manufacturing process.

Another object of the present invention is to provide a method for producing a block copolymer that can easily control the molecular weight and microstructure of living polymers produced from vinyl monomers or diene monomers.

It is another object of the present invention to provide a method for easily block copolymerizing vinyl-based or diene-based living polymers with alkylene oxide in a single reactor in a non-polar solvent.

According to one feature of the present invention, there is provided a method for producing a polyalkylene oxide, in which purification after production is simple and molecular weight can be easily adjusted. This process involves the use of a solvent selected from the group consisting of benzene, toluene, cyclohexane, hexane, tetrahydrofuran and tetrahydropyrene in the presence of an initiator of an appropriate molar ratio of alkali metal alkoxide / alkyllithium mixture to It consists of anionic polymerization.

Examples of the monomer used in the production of the polyalkylene oxide polymer in the present invention include epoxide-based monomers represented by the following formula (1).

Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, a lower alkyl or a phenyl group. In particular, ethylene oxide and propylene oxide are preferable.

As an initiator, the initiator which mixed an alkali metal alkoxide type | system | group substance with an alkali metal, ie, n-butyllithium, sec-butyllithium, tert- butyllithium, etc. by following formula (II) at an appropriate ratio is used.

Wherein R ₅ is methyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl or amyl group and Mt is lithium, sodium or potassium.

The preferable mixing molar ratio of alkyl lithium and alkoxide is 10-0.5.

As the solvent, non-polar hydrocarbon solvents such as benzene, toluene, cyclohexane, hexane and the like, as well as polar solvents such as THF and THP (tetrahydropyrene) can be used.

According to a second aspect of the present invention, a vinyl-based or diene-based polymer prepared by lipopolymerization in the presence of an alkyllithium initiator may be separated from an alkylene oxide in the presence of an alkali metal alkoxide in an appropriate ratio with respect to alkyllithium. A method of producing a copolymer of high purity, which comprises block copolymerization in a reactor, is provided.

That is, the method for producing a block copolymer of the present invention comprises the steps of: (a) living polymerization of a vinyl monomer or a diene monomer using an alkyl lithium as an initiator in a nonpolar solvent and (b) an alkali metal alkoxide and an alkyl lithium. An alkali metal alkoxide having an molar ratio of 10 to 0.5 is mixed with the living polymer prepared in step (a), followed by continuous addition of an epoxide monomer to block copolymerization.

Examples of the epoxide monomer used in the block copolymerization method of the present invention include epoxide monomers represented by the following formula (I).

Wherein R ₁ , R ₂ , R ₃ and R ₄ are each independently a hydrogen atom, a lower alkyl or a phenyl group. In particular, ethylene oxide and propylene oxide are preferable.

As the comonomer used in the block copolymerization method of the present invention, all vinyl monomers represented by the following formula (III) include diene monomers represented by the following formula (IV).

Wherein R ' ₁ and R' ₂ each independently represent a hydrogen atom, a phenyl group ester group, an acrylate group or a substituted phenyl group, and R ' ₃ , R' ₄ , R ' ₆ , R' ₇ and R ' ₈ are A hydrogen atom or a methyl group, R ' ₅ represents a hydrogen atom, a methyl group or a chloro group.

The polymerization method used for the polymerization of the vinyl- or diene-based monomer is a living polymerization method. After the monomers are all consumed in the polymerization reactor, when the same monomer is injected, the molecular weight increases again and the reaction is continued. Characterized in that consumed by the reaction.

In the method of the present invention, first, a vinyl or diene monomer is subjected to living polymerization in a nonpolar solvent with alkyllithium as an initiator. As the solvent, non-polar solvents such as benzene, toluene, cyclohexane, hexane and the like can be used. The living polymer thus produced has a structure with a lithium group at the end. For example, polystyryl lithium, polycutadienyl lithium, and the like are produced, but the living polymer is mixed with alkyllithium alkoxide in an appropriate ratio with respect to alkyllithium, followed by block copolymerization by addition of an epoxide monomer. . Particularly preferred alkoxides of alkali metals are alkali metal methoxide, propyl oxide, n-butoxide, sec-butoxide, tert-butoxide and amyl oxide. The molar ratio of alkali metal alkoxide to alkyllithium is 10 to 0.5. The copolymerization temperature is in the range of 5 to 70 ° C.

Conventional living anion polymerizations are described in Rubber chemistry and Technology, Vol. 43, pages 22-73, and the synthesis of general block copolymers is disclosed in US Pat. No. 3,294,768. However, as in the present invention, synthesizing a block copolymer of a vinyl-based or diene-based monomer and an epoxide-based monomer king in a non-polar solvent in a single reactor is a novel synthesis method that is not known at all.

Hereinafter, although an Example is given and this invention is demonstrated in detail, the scope of the present invention is not limited by these Examples.

Example 1

45 ml of benzene and 40 ml of ethylene oxide were fractionally distilled (purity: 99.9%) to form a monomer ampoule, and attached to the reactor. 4.3 ml of n-buttal lithium (1.6 mol / cyclohexane) and potassium tert-butoxide were added to the number of moles of alkyllithium. Doubled and injected into the reactor under argon gas, respectively. The reactor was again evacuated using a vacuum pump. At this time, the degree of vacuum was 10 ^-6 mmHg, the outside temperature of the reactor was maintained at about -78 ℃ using a dry ice / isopropyl alcohol temperature control tank, and the ethylene oxide contained in the ampoule was injected into the reactor 1 hour, The temperature was gradually raised over the reaction and allowed to react for 3 days at room temperature while stirring using a conventional Teflon-coated magnetic stirrer.

The degree of polymerization of the pure polyethylene oxide obtained from this example was 110, the molecular weight was 5,000, and the molecular weight distribution was about 2.0 measured using polystyrene as a sample sample on a gel-to-chromatography (GPC) machine. In addition, the polymer obtained in this embodiment is generally dissolved in alcohol, mole, THF, and precipitated and separated in hexane and pentane and can be used for various purposes without a separate purification step.

Example 2

Instead of the potassium alkoxide described in Example 1, sodium alkoxide was measured and dissolved in tetrahydrofuran in the same amount as the molar number of alkyllithium to make an ampoule, which was attached to the reactor, and then the same amount of ethylene oxide as in Example 1 was again converted into ampoules. After making and attaching to the reactor, alkyllithium and sodium alkoxide were injected into the reactor under the same conditions as in Example 1, and then ethylene oxide monomer was injected and heated to react for 3 days. The molecular weight of the polymer thus prepared is 1,000, and precipitation and separation are carried out in the same manner as in Example 1.

Example 3

The polymerization was carried out under the same reaction conditions as in Example 1 with the same amounts of the initiators as those described in Example 1 and twice the amount of the monomers. The prepared polymer had a molecular weight of 10,000 and a molecular weight distribution of 2.0.

Example 4

After separating a certain amount of the polymerization solution polymerized in Example 1, living polymerizability was tested by a continuous monomer addition method in which an ethylene oxide monomer was added in the same manner as in Example 1. 20 ml of monomer and half of the solution of Example 1 were taken. At this time, the concentration of the chain terminal in the polymerization solution was calculated as half of the initial concentration, and was polymerized in the same manner as in Example 1. The molecular weight of the produced polymer was 10,000, the molecular weight distribution was 1.0.

Example 5

Living polystyrene was synthesized using purified styrene (purity: 99.9%, moisture content: 0.001% or less) under vacuum or inert gas using benzene as a solvent. Thus prepared living polystyrene (polyhydrylithium) was used as an initiator instead of the low molecular weight alkyllithium of Example 1, and the ethylene oxide monomer was injected into the reactor in the same manner as in Example 3, and then the block air was prepared by a conventional monomer addition method. Copolymerization was carried out in the same manner as the synthesis method.

An appropriate amount of polymerization solution was taken so that the molecular weight of the produced polystyrene was 10,000. Because of the living polymerization, the activity at the end of the chain was alive, so that the molar ratio with potassium tert-butoxide was 1, and the reactor was added again, and the ethylene oxide monomer was added at a molecular weight of 10,000. The polymerization was carried out in the same manner as in Example 1. The total molecular weight of the prepared block copolymer was 20,000, the molecular weight distribution was 1.5, and precipitated in hexane or petane to separate the polymer.

Example 6

After synthesizing living polybutadiene (polybutadienyl lithium) as in Example 5, again mixed polybutadienyl lithium (1.6 mol) with potassium tert-boxide instead of n-butyllithium of Example 1 and ethylene oxide The monomer was added to the reactor, and then heated to copolymerize for 3 days with stirring at 50 ° C. The total molecular weight of the prepared block copolymer was 20,000, the molecular weight distribution was 1.9, and the polymer was isolated by precipitating in petane.

Example 7

As in Example 5, 6.88 × 10 ⁻³ mol of living polystyrene (polystyryl lithium) having a molecular weight of 10,000 and 0.014 mol of potassium tert-butoxide were mixed and then copolymerized by injecting phenyl epoxide (100 mol). The total molecular weight of the prepared block copolymer was 20,000, the molecular weight distribution was 2.2, and precipitated in hexane to separate the polymer.

Claims (3)

(A) Living polymerizing a vinyl monomer of formula (III) or diene monomer of formula (IV) using alkyllithium as an initiator in a nonpolar solvent selected from the group consisting of benzene, toluene, cyclohexane and hexane Step and (b) an alkali metal alkoxide having an molar ratio of 10 to 0.5 of an alkali metal alkoxide and alkyl lithium is mixed with the living polymer prepared in step (a), and then the epoxide system represented by the following formula (I) A block copolymerization method of an alkylene oxide and a vinyl-based or diene-based monomer, characterized in that the step of block copolymerization by continuously adding a monomer. The method of claim 1, wherein the epoxide monomer is ethylene oxide or propylene oxide. The method according to claim 1 or 2, wherein the alkyl lithium is n-butyl lithium, sec-butyl lithium or tert-butyl lithium, and the alkali metal alkoxide is represented by the following formula (II). Wherein R ₅ is methyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl or amyl group and Mt is lithium, sodium or potassium.