NOVEL ANIONIC POLYMERIZATION INITIATOR AND METHOD FOR PREPARING CONJUGATED DIENE-BASED POLYMER USING SAME

Abstract

Disclosed are an anionic polymerization initiator, which is a reaction product of an organometallic compound and a compound including an alkyl chain having a tertiary amino functional group, and a method of preparing a conjugated diene-based copolymer using the same.

Claims

1. An anionic polymerization initiator, which is a reaction product of an organometallic compound and a compound including an alkyl chain having a tertiary amino functional group represented by Chemical Formula 1 below: ##STR00005## in Chemical Formula 1, R.sub.1 to R.sub.5 are each independently hydrogen or a C1-C20 hydrocarbon group, two substituents are able to form a single aliphatic or aromatic ring, and at least two of R.sub.1 to R.sub.5 are alkyl groups; R.sub.6 and R.sub.7 are a C1-C14 aliphatic hydrocarbon group or a C5-C14 aromatic hydrocarbon group, two substituents being able to form a single aliphatic or aromatic ring when n is 2 or more; and n is 1 to 12.

2. The anionic polymerization initiator of claim 1, wherein the compound represented by Chemical Formula 1 is 1-(diethylaminomethyl)-2,4,6-methylbenzene or 1-(diisopropylaminomethyl)-2,4,6-methylbenzene.

3. The anionic polymerization initiator of claim 1, wherein the organometallic compound is alkyl lithium.

4. A method of preparing a conjugated diene-based polymer, comprising polymerizing a conjugated diene monomer or a conjugated diene monomer and an aromatic vinyl monomer in presence of a solvent using an anionic polymerization initiator, which is a reaction product of an organometallic compound and a compound including an alkyl chain having a tertiary amino functional group represented by Chemical Formula 1 below: ##STR00006## in Chemical Formula 1, R.sub.1 to R.sub.5 are each independently hydrogen or a C1-C20 hydrocarbon group, two substituents are able to form a single aliphatic or aromatic ring, and at least two of R.sub.1 to R.sub.5 are alkyl groups; R.sub.6 and R.sub.7 are a C1-C14 aliphatic hydrocarbon group or a C5-C14 aromatic hydrocarbon group, two substituents being able to form a single aliphatic or aromatic ring when n is 2 or more; and n is 1 to 12.

5. The method of claim 4, wherein the reaction product of the organometallic compound and the compound including an alkyl chain having a tertiary amino functional group represented by Chemical Formula 1 is used in an amount of 0.01 to 10 mmol based on 100 g in total of the monomer.

6. The method of claim 4, wherein the polymerizing is performed with additional use of a polar additive.

7. The method of claim 6, wherein the polar additive is added in an amount of 0.001 to 10 g based on 1 mmol in total of the reaction product of the organometallic compound and the compound including an alkyl chain having a tertiary amino functional group represented by Chemical Formula 1.

8. A conjugated diene-based polymer, prepared by the method of claim 4.

9. A conjugated diene-based polymer, prepared by the method of claim 5.

10. A conjugated diene-based polymer, prepared by the method of claim 6.

11. A conjugated diene-based polymer, prepared by the method of claim 7.

Description

SYNTHESIS EXAMPLE 1

First Step: Preparation of 1-(diethylaminomethyl)-2,4,6-trimethylbenzene

[0051] 1-(bromomethyl)-2,4,6-trimethylbenzene (0.5 g, 2.4 mmol) was dissolved in 10 mL of toluene in a 50 mL Schlenk flask, and 3 equivalents of potassium carbonate (0.97 g, 7.0 mmol) and diethylamine (0.52 g, 7.0 mmol) were added and stirred for 20 hr with refluxing. After the reaction, the salt was removed using a glass filter filled with celite. The organic solvent was removed under reduced pressure, yielding 87% (0.42 g) of 1-(diethylaminomethyl)-2,4,6-trimethylbenzene as colorless oil:

[0052] .sup.1HNMR (500 MHz, solvent CDCl.sub.3): ppm 6.82 (1H, s, Ph-H), 3.50 (4H, s, Ph-CH.sub.2N), 2.47 (4H, q, Et-H), 2.37 (6H, s, CH.sub.3), 2.26 (3H, s, CH.sub.3), 1.01 (6H, t, CH.sub.3); .sup.13C NMR (125 MHz, solvent CDCl.sub.3): ppm 138.07 (C-2), 135.89 (C-4,6), 133.14 (C-1,3), 128.82 (C-5), 51.90, 46.23, 20.86, 20.18, 12.10.

Second Step: Preparation of Lithium 1-(diethylaminomethyl)-2,4,6-trimethylbenzene Initiator

[0053] The 1-(diethylaminomethyl)-2,4,6-trimethylbenzene was placed in a 50 mL storage flask, and 10 mL of anhydrous n-hexane was added in a nitrogen atmosphere, after which the resulting solution was cooled to 78 C., and 2.5 M n-butyllithium was added dropwise, followed by stirring while the temperature was maintained for 1 hr. Then, the cooling bath was removed, and stirring was performed at room temperature for 2 hr, yielding a pale yellow solution as an initiator.

SYNTHESIS EXAMPLE 2

First Step: Preparation of 1-(diisopropylaminomethyl)-2,4,6-trimethylbenzene

[0054] 79% (0.60 g) of 1-(diisopropylaminomethyl)-2,4,6-trimethylbenzene was obtained as colorless oil in the same manner as in the First Step of Synthesis Example 1, with the exception that 3 equivalents of diisopropylamine (1.38 mL, 9.9 mmol) were used in lieu of diethylamine:

[0055] .sup.1HNMR (500 MHz, solvent CDCl.sub.3): ppm 6.79 (1H, s, Ph-H), 3.65 (4H, s, Ph-CH.sub.2N), 2.89 (4H, m, iPr-H), 2.38 (6H, s, CH.sub.3), 2.24 (3H, s, CH.sub.3), 1.03 (24H, d, CH.sub.3); .sup.13C NMR (125 MHz, solvent CDCl.sub.3): ppm 138.42 (C-2), 135.61 (C-4,6), 133.46 (C-1,3), 128.95 (C-5), 46.21, 42.69, 20.96, 20.79, 20.36.

Second Step: Preparation of Lithium 1-(diisopropylaminomethyl)-2,4,6-trimethylbenzene Initiator

[0056] A pale yellow solution initiator was prepared in the same manner as in the Second Step of Synthesis Example 1, with the exception that 1-(diisopropylaminomethyl)-2,4,6-trimethylbenzene was used as the reactant.

COMPARATIVE SYNTHESIS EXAMPLE 1

First Step: Preparation of 1-(diethylaminomethyl)-2-methylbenzene

[0057] 1-(bromomethyl)-2-methylbenzene (1.0 g, 8.1 mmol) was dissolved in 20 mL of toluene in a 50 mL Schlenk flask, and 2 equivalents of potassium carbonate (2.24 g, 16.2 mmol) and diethylamine (1.19 g, 16.2 mmol) were added and stirred for 20 hr with refluxing. After the reaction, the salt was removed using a glass filter filled with celite. The organic solvent was removed under reduced pressure, yielding 84% (1.21 g) of 1-(diethylaminomethyl)-2-methylbenzene as colorless oil.

Second Step: Preparation of Lithium 1-(diethylaminomethyl)-2-methylbenzene Initiator

[0058] The 1-(diethylaminomethyl)-2-methylbenzene was placed in a 50 mL storage flask, and 10 mL of anhydrous n-hexane was added in a nitrogen atmosphere, after which the resulting solution was cooled to 78 C., and 2.5 M n-butyllithium was added dropwise, followed by stirring while the temperature was maintained for 1 hr. Then, the cooling bath was removed, and stirring was performed at room temperature for 2 hr, yielding a pale yellow solution as an initiator.

EXAMPLE 1

[0059] 6 g of styrene and 44 g of anhydrous n-hexane were added into a 100 mL glass reactor and heated with stirring so that the internal temperature of the reactor was adjusted to 60 C. The initiator (0.5 mmol based on lithium) of Synthesis Example 1 was added into the reactor, followed by an adiabatic heating reaction. After the reaction for 60 min, the reaction was terminated by the addition of 10 mL of methanol into the reactor. The reaction product was reprecipitated in 200 mL of methanol, after which only insoluble solids were dried under reduced pressure, thus obtaining a polymer. The yield was calculated using the amount of the polymer thus obtained. The results of analysis of the polymer are shown in Table 1 below.

EXAMPLE 2

[0060] A polymer was prepared in the same manner as in Example 1, with the exception that butadiene (7.5 g), in lieu of styrene, and n-hexane (42.5 g) were used. The results of analysis of the polymer are shown in Table 1 below.

EXAMPLE 3

[0061] A polymer was prepared in the same manner as in Example 1, with the exception that styrene (3.0 g), butadiene (7.5 g) and n-hexane (42.5 g) were used. The results of analysis of the polymer are shown in Table 1 below.

COMPARATIVE EXAMPLE 1

[0062] A polymer was prepared in the same manner as in Example 1, with the exception that a 2.5 M n-butyllithium hexane solution (0.2 mL, 0.5 mmol) was used as the initiator. The results of analysis of the polymer are shown in Table 1 below.

COMPARATIVE EXAMPLE 2

[0063] A polymer was prepared in the same manner as in Example 1, with the exception that a 2.5 M n-butyllithium hexane solution (0.2 mL, 0.5 mmol) was used as the initiator, and butadiene (7.5 g), in lieu of styrene, and n-hexane (42.5 g) were used. The results of analysis of the polymer are shown in Table 1 below.

COMPARATIVE EXAMPLE 3

[0064] A polymer was prepared in the same manner as in Example 1, with the exception that a 2.5 M n-butyllithium hexane solution (0.2 mL, 0.5 mmol) was used as the initiator, and styrene (3.0 g), butadiene (7.5 g) and n-hexane (42.5 g) were used. The results of analysis of the polymer are shown in Table 1 below.

COMPARATIVE EXAMPLE 4

[0065] A polymer was prepared in the same manner as in Example 1, with the exception that the initiator (0.5 mmol based on lithium) of Comparative Synthesis Example 1 was used. The results of analysis of the polymer are shown in Table 1 below.

COMPARATIVE EXAMPLE 5

[0066] A polymer was prepared in the same manner as in Example 1, with the exception that the initiator (0.5 mmol based on lithium) of Comparative Synthesis Example 1 was used, and butadiene (7.5 g), in lieu of styrene, and n-hexane (42.5 g) were used. The results of analysis of the polymer are shown in Table 1 below.

COMPARATIVE EXAMPLE 6

[0067] A polymer was prepared in the same manner as in Example 1, with the exception that the initiator (0.5 mmol based on lithium) of Comparative Synthesis Example 1 was used, and styrene (3.0 g), butadiene (7.5 g) and n-hexane (42.5 g) were used. The results of analysis of the polymer are shown in Table 1 below.

Molecular Average Molecular Weight (Mw), Number Average Molecular Weight (Mn), and Molecular Weight Distribution (MWD)

[0068] The polymers of Examples 1 to 3 and Comparative Examples 1 to 6 were analyzed through GPC at 40 C. The column herein used was a combination of two PLgel Olexis columns and one PLgel mixed-C column, made by Polymer Laboratories, and all of the replaced columns were mixed bed-type columns. Also, polystyrene (PS) was the GPC standard material for the calculation of molecular weight.

TABLE-US-00001 TABLE 1 Sty- Buta- rene diene Yield GPC (10.sup.3) Initiator (g) (g) (%) Mn MWD Ex. 1 Lithium 1- 6 83.7 84.3 1.314 (diethylaminomethyl)- 2,4,6-trimethylbenzene Ex. 2 Lithium 1- 7.5 84.0 22.6 1.177 (diethylaminomethyl)- 2,4,6-trimethylbenzene Ex. 3 Lithium 1- 3 7.5 75.1 39.9 1.225 (diethylaminomethyl)- 2,4,6-trimethylbenzene C. Ex. 1 n-BuLi 6 78.7 49.7 1.377 C. Ex. 2 n-BuLi 7.5 75.0 23.0 1.062 C. Ex. 3 n-BuLi 3 7.5 64.8 27.0 1.114 C. Ex. 4 Lithium 1- 6 80.3 63.2 1.354 (diethylaminomethyl)- 2-methylbenzene C. Ex. 5 Lithium 1- 7.5 75.0 27.8 1.125 (diethylaminomethyl)- 2-methylbenzene C. Ex. 6 Lithium 1- 3 7.5 70.6 32.9 1.183 (diethylaminomethyl)- 2-methylbenzene

[0069] In the styrene polymerization of Example 1 using the initiator of Synthesis Example 1 under the same conditions, much higher molecular weight than that of Comparative Example 1 was obtained. In all of the examples using the initiator of Synthesis Example 1, higher yield could be obtained than in the comparative examples. Also, based on the results of comparison testing depending on the number of alkyl chains in the benzene anion (Examples 1, 2, 3 and Comparative Examples 4, 5, 6), as the number of alkyl chains was increased, high yield, high molecular weight, and good molecular weight distribution control resulted.