WO2014084559A1

WO2014084559A1 - Method for preparing polycarbonate

Info

Publication number: WO2014084559A1
Application number: PCT/KR2013/010744
Authority: WO
Inventors: Jin Su Ham; Yu Na Shim; Hyo Seung Park; Jong Ho Lim
Original assignee: Sk Innovation Co.,Ltd.; Sk Global Chemical Co., Ltd.
Priority date: 2012-11-29
Filing date: 2013-11-25
Publication date: 2014-06-05

Abstract

Provided is a method for preparing polycarbonate, and more particularly, a method for preparing polycarbonate in which polymerization of polycarbonate is performed via a one-pot process together with oxidizing an organic transition metal catalyst not having a polymerization activity in-situ.

Description

METHOD FOR PREPARING POLYCARBONATE

The present invention relates to a method for preparing polycarbonate, and more particularly, to a method for preparing polycarbonate in which polymerization of polycarbonate is performed via a one-pot process simultaneously with oxidizing an organic transition metal catalyst not having a polymerization activity in-situ.

The natural environment has been destroyed due to the development of international industries and population growth, and economical and social pressures against contamination of the natural environment have also been intensified at the national level.

Particularly, polymers such as plastic contribute to convenience of our daily lives and development of various modern industries, but as an amount of the used polymer is increased, environmental contamination by waste polymers discarded after being used has also been significantly increased.

Therefore, recently, as an alternative to a petrochemical thermoplastic material, research into polycarbonates, which are derived from a recyclable resource, has been actively conducted.

Among them, aliphatic polycarbonate, which is a biodegradable polymer having excellent processability into a soft rubber phase plastic and an easily controlled degradation property by nature, is useful as a raw material for fabrics, packing materials, films, sheets, paints, adhesives, and the like. The aliphatic polycarbonate is prepared from an epoxide compound and carbon dioxide or prepared through ring open polymerization of cyclic carbonate.

A method for preparing the aliphatic polycarbonate from the epoxide compound and carbon dioxide has eco-friendly high value in that phosgene, which is a toxic compound, is not used, and carbon dioxide may be cheaply obtained.

Since 1960s, many researchers have developed various type catalysts in order to prepare the polycarbonate from the epoxide compound and carbon dioxide. An organic transition metal catalyst having a high oxidation state, synthesized from a [salen; ([H₂Salen = N,N'-bis(3,5-dialkylsalicylidene)-1,2-ethylenediamine]-type ligand was used in polymerization of the epoxide compound and carbon dioxide (Korean Patent No. 10-0853358 and Korean Patent Laid-Open Publication No. 10-2011-0112061). However, the organic transition metal catalyst prepared in advance in the high oxidation state may be partially reduced during storage and preservation, such that a catalytic activity may be decreased. In addition, at the time of preparing a large amount of the organic transition metal catalyst in the high oxidation state, an additional oxidant or pure oxygen gas should be used, but in the case of using the oxidant, after a reaction is completed, a catalyst separating process is required, such that a process step may be increased, which is not economical. Further, in the case of using pure oxygen gas, a fire risk may be significantly high.

Therefore, in preparing polycarbonate, it is necessary to maximize economic efficiency by decreasing a loss of the catalyst while securing simplicity of the process and secure safety and stability.

An object of the present invention is to provide a method for preparing polycarbonate.

In one general aspect, a method for preparing polycarbonate includes: 1) putting epoxide compound, a cobalt (II) or chromium (II) catalyst including a salen ligand, and a chain transfer agent into a reactor and injecting air thereinto; and 2) injecting carbon dioxide to the reactor to polymerize epoxide and carbon dioxide.

The epoxide compound may be at least one selected from a group consisting of (C2-C20)alkyleneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, or (C6-C20)aryl(C1-C20)alkyloxy; (C4-C20)cycloalkyleneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, or (C6-C20)aryl(C1-C20)alkyloxy; and (C8-C20)styreneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, (C6-C20)aryl(C1-C20)alkyloxy, or (C1-C20)alkyl.

The chain transfer agent, which is a compound having a plurality of sites capable of initiating polymerization of carbon dioxide and epoxide, may be represented by the following Chemical Formula 1:

[Chemical Formula 1]

J(LH)_a

In Chemical Formula 1, J is an a-valent hydrocarbyl radical having 1 to 60 carbon atoms with or without an ether, ester, or amine group; each LH is independently -OH, -CO₂H, -C(OR^z)OH, -OC(R^z)OH, -NHR^z, -NHC(O)R^z, -NHC=NR^z, -NR^zC=NH, -NR^zC(NR^z ₂)=NH, -NHC(NR^z ₂)=NR^z, -NHC(O)OR^z, -NHC(O)NR^z ₂, -C(O)NHR^z, -C(S)NHR^z, -OC(O)NHR^z, -OC(S)NHR^z, -SH, -C(O)SH, -B(OR^z)OH, -P(O)_b(R^z)_c(OR^z)_d(O)_eH, -OP(O)_b(R^z)_c(OR^z)_d(O)_eH, -N(R^z)OH, -ON(R^z)H, =NOH, or =NN(R^z)H; each R^z is independently hydrogen, (C1-C20)alkyl, (C3-C20)cycloalkyl, (C1-C20)heteroaliphatic alkyl, 3- to 12-membered heterocyclic, or (C6-C12)aryl; a is an integer of 1 to 10, when a is 2 or more, LH(s) may be the same as or different from each other; and b and c are each independently 0 or 1, d is 0, 1, or 2, e is 0 or 1, and a sum of b, c, and d is 1 or 2.

In the chain transfer agent of Chemical Formula 1, LH may be -OH or -CO₂H; and a may be an integer of 1 to 4.

The cobalt (II) or chromium (II) catalyst including the salen ligand may be represented by the following Chemical Formula 2:

[Chemical Formula 2]

In Chemical Formula 2,

M is cobalt (II) or chromium (II);

A is an oxygen or sulfur atom;

Q is a diradical linking two nitrogen atoms;

R', R'' and R''' are each independently hydrogen; halogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; (C6-C20)arylcarbonyl; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl; and

two of R', R'' and R''' may be linked to each other to form a ring, and the formed ring is further substituted with at least one selected from a group consisting of halogen; cyano; nitro; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; and (C6-C20)arylcarbonyl.

The cobalt (II) or chromium (II) catalyst including the salen ligand may be represented by the following Chemical Formula 3:

[Chemical Formula 3]

In Chemical Formula 3,

M is cobalt (II) or chromium (II);

A is an oxygen or sulfur atom;

Q is a diradical linking two nitrogen atoms;

R¹ to R¹⁰ are each independently hydrogen; halogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; (C6-C20)arylcarbonyl; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl;

two of R¹ to R¹⁰ may be linked to each other to form a ring;

at least one of the hydrogens contained in R¹ to R¹⁰ and Q is substituted with a proton group selected from a group consisting of Chemical Formulas a, b, and c:

[Chemical Formula a]

[Chemical Formula b]

[Chemical Formula c]

each X^- is independently a halide ion; HCO₃ ^-; BF₄ ^-; ClO₄ ^-; NO₃ ^-; PF₆ ^-; (C6-C20)aryloxy anion; (C6-C20)aryloxy anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkylcarboxyl anion; (C1-C20)alkylcarboxyl anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)arylcarboxyl anion; (C6-C20)arylcarboxyl anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy anion; (C1-C20)alkoxy anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and an phosphorus atom; (C1-C20)alkylcarbonate anion; (C1-C20)alkylcarbonate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)arylcarbonate anion; (C6-C20)arylcarbonate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkylsulfonate anion; (C1-C20)alkylsulfonate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkylamido anion; (C1-C20)alkylamido anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)arylamido anion; (C6-C20)arylamido anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkylcarbamate anion; (C1-C20)alkylcarbamate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; or (C6-C20)arylcarbamate anion; and (C6-C20)arylcarbamate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom;

Z is a nitrogen or phosphorus atom;

R²¹, R²², R²³, R³¹, R³², R³³, R³⁴, and R³⁵ are each independently (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl; and two of R²¹, R²², and R²³ or two of R³¹, R³², R³³, R³⁴, and R³⁵ may be linked to each other to form a ring;

R⁴¹, R⁴², and R⁴³ are each independently hydrogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl; two of R⁴¹, R⁴², and R⁴³ may be linked to each other to form a ring;

X' is an oxygen atom, a sulfur atom, or N-R (here, R is (C1-C20)alkyl);

n, which is a total number of proton groups contained in R¹ to R¹⁰ and Q is a positive integer; and

a nitrogen atom of imine is coordinated with or de-coordinated from M.

In the chain transfer agent of Chemical Formula 1, a may be 1; LH may be -OH or -CO₂H; J may be -[CR⁵¹R⁵²]_n-CR⁵³R⁵⁴R⁵⁵, phenyl, or naphthyl; n may be an integer of 0 to 20; and R⁵¹ to R⁵⁵ may be the same as or different from each other and be hydrogen, methyl, ethyl, propyl, or butyl.

In the chain transfer agent of Chemical Formula 1, a may be 2; LH(s) may be the same as or different from each other and may be -OH or -CO₂H; J may be -[CR⁵¹R⁵²]_n-, para-phenylene, metha-phenylene, ortho-phenylene, 2,6-naphthalendiyl, -CH₂CH₂N(R⁵⁶)CH₂CH₂-, or -[CH₂CH(R⁵⁶)O]_mCH₂CH(R)-; n may be an integer of 1 to 20; R⁵¹, R⁵², and R⁵⁶ may be the same as or different from each other and be hydrogen, methyl, ethyl, propyl, or butyl; and m may be an integer of 1 to 10.

In the chain transfer agent of Chemical Formula 1, a may be 3; LH may be -CO₂H; and J may be 1,2,3-propanetriyl, 1,2,3-benzenetriyl, 1,2,4-benzenetriyl, or 1,3,5-benzenetriyl.

In the chain transfer agent of Chemical Formula 1, a may be 4; LH may be -CO₂H; and J may be 1,2,3,4-butanetetrayl or 1,2,4,5-benzenetetrayl.

In step 1), a solvent may be further put into the reactor.

The solvent may be at least one selected from a group consisting of aromatic hydrocarbons, halogenated hydrocarbons, ethers, and esters.

The solvent may be at least one selected from a group consisting of toluene, dichloromethane, dichloroethane, tetrahydrofuran, and ethylacetate.

A molar ratio of the epoxide compound : the catalyst may be 100:1 to 1,000,000:1.

The method for preparing polycarbonate according to the exemplary embodiment of the present invention does not require a separate catalyst preparing step, such that simplicity of the entire process may be secured, and the catalyst loss generated during the manufacturing process may be decreased, thereby making it possible to decrease a preparing cost of the catalyst and process cost.

Further, in the case of preparing the transition metal catalyst in a high oxidation state used in polymerization in advance, the catalyst is partially reduced during storage and preservation of the catalyst, such that the catalytic activity may be deteriorated, but as in the present invention, in the case of in-situ oxidizing the metal catalyst not having the polymerization activity, since there is no need to take care of storage and preservation of the catalyst and the activity due to reduction of the catalyst is not generated, such that stability may be secured.

In addition, in order to prepare a large amount of an organic transition metal catalyst in a high oxidation state that is used in polymerization, an additional oxidant or pure oxygen gas should be used. In the case of using the oxidant, after reaction, a catalyst separating process is required, and in the case of using pure oxygen gas, a fire risk may be significantly high, such that it may be difficult to secure stability. On the other hand, in the present invention, since cobalt (II) or chromium (II) catalyst that does not have the polymerization activity but is only metallated is oxidized in-situ using air, which is a mixed gas having a low fire risk, to thereby be used in polymerization, the present invention is advantageous in view of safety.

The present invention provides a method for preparing polycarbonate, more particularly, the method for preparing polycarbonate including:

1) putting epoxide compound, a cobalt (II) or chromium (II) catalyst including a salen ligand, and a chain transfer agent into a reactor and injecting air thereinto; and

2) injecting carbon dioxide into the reactor to polymerize epoxide and carbon dioxide.

According to the method for preparing polycarbonate according to the present invention, which is to prepare polycarbonate having a high molecular weight and narrow molecular weight distribution simultaneously with oxidizing a cobalt (II) or chromium (II) catalyst that does not have the polymerization activity but is only metallated in-situ in the case of injecting the cobalt (II) or chromium (II) catalyst including the salen ligand, since there is no need to prepare a transition metal catalyst in a high oxidation state (Korean Patent Laid-Open Publication No. 10-2011-0112061) in advance, which is used in polymerization according to the related art, and a problem such as catalytic activity deterioration due to partial reduction of the catalyst during storage and preservation of the catalyst may be prevented.

That is, in the method for preparing polycarbonate according to the present invention, since a catalyst in a high oxidation state is not used, there is no need to take care of storage and preservation of the catalyst. Further, since activity deterioration due to reduction of the catalyst is not generated, stability may be secured.

In the method for preparing polycarbonate according to an exemplary embodiment of the present invention, in order to oxidize cobalt (II) or chromium (II) catalyst that does not have the polymerization activity but is only metallated in-situ to use the oxidized catalyst in polymerization, in step 1), air is injected. On the other hand, in order to prepare a large amount of an organic transition metal catalyst in a high oxidation state that is used in polymerization according to the related art, an additional oxidant or pure oxygen gas should be used. There are problems in that, in the case of using the oxidant, after reaction, a catalyst separating process is required, and in the case of using pure oxygen gas, a fire risk is significantly high, such that it may be difficult to secure stability. In order to solve these problems, in the present invention, since cobalt (II) or chromium (II) catalyst that does not have a polymerization activity but is only metallated is oxidized in-situ using air, which is a mixed gas having a low fire risk, to thereby be used in polymerization, the present invention is advantageous in view of safety.

A pressure of the air injected in step 1) is not limited, but may be, preferably 1 to 30 atm.

As the chain transfer agent according to the exemplary embodiment of the present invention, any compound may be used as long as it has a plurality of sites at which copolymerization of carbon dioxide and epoxide may be initiated, but a compound represented by the following Chemical Formula 1 may be preferably used:

[Chemical Formula 1]

J(LH)_a

An example of the chain transfer agent of Chemical Formula 1 may include polyols, specifically, diol, triol, tetraol, or the like. A specific example of the diol may include 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethylpropane-1,3-diol, 2-butyl-2-ethylpropane-1,3-diol, 1,5-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol, 2,2,4,4-tetramethylcyclobutane-1,3-diol, 1,3-cyclopentanediol, 1,2-cyclohexanediol, 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 1,4-cyclohexanediethanol, 4,4'-(1-methylethylidene)bis[cyclohexanol], 2,2'-methylenebis[phenol], 4,4'-methylenebis[phenol], 4,4'-(phenylmethylene)bis[phenol], 4,4'-(diphenylmethylene)bis[phenol], 4,4'-(1,2-ethanediyl)bis[phenol], 4,4'-(1,2-cyclohexanediyl)bis[phenol], 4,4'-(1,3-cyclohexanediyl)bis[phenol], 4,4'-(1,4- cyclohexanediyl)bis[phenol], 4,4'-ethyllidenebis[phenol], 4,4'-(1-phenylethylidene)bis[phenol], 4,4'-propylidenebis[phenol], 4,4'-cyclohexylidenebis[phenol], 4,4'-(1-methylethylidene)bis[phenol], 4,4'-(1-methylpropylidene)bis[phenol], 4,4'-(1-ethylpropylidene)bis[phenol], 4,4'-cyclohexylidenebis[phenol], 4,4'-(2,4,8,10-tetraoxaspiro[5.5]undecane-3,9-diyldi-2,1-ethandiyl)bis[phenol], 1,2-benzenedimethanol, 1,3-benzenedimethanol, 1,4-benzenedimethanol, 4,4'-[1,3-phenylenebis(1-methylethylidene)]bis[phenol], 4,4'-[1,4-phenylenebis(1-methylethylidene)]bis[phenol], phenolphthalein, 4,4'-(1-methylidene)bis[2-methylphenol], 4,4'-(1-methylethylidene)bis[2-(1-methylethyl)phenol], 2,2'-methylenebis[4-methyl-6-(1-methylethyl) phenol], and the like. In addition, a specific example of the triol may include trimethylolethane; trimethylolpropane; glycerol; 1,2,4-butanetriol; 1,2,6-hexanetriol; tris(2-hydroxyethyl)isocyanurate; hexahydro-1,3,5-tris(hydroxyethyl)-s-triazine; 6-methylheptane-1,3,5-triol; polypropylene oxide triol; and aliphatic triols having a molecular weight smaller than 500 such as polyester triol, and the like. A specific example of the tetraol may include erythritol, pentaerythritol, 2,2'-dihydroxymethyl-1,3-propandiol, 2,2'-(oxydimethylene)bis-(2-ethyl-1,3-propandiol), and the like.

In addition, an example of the chain transfer agent of Chemical Formula 1 may include diethylene glycol, triethylene glycol, tetraethylene glycol, higher poly(ethylene glycol) (preferably, having a number average molecular weight of 220 to about 2000g/mol), dipropylene glycol, tripropylene glycol, and higher poly(propylene glycol) (preferably, having a number average molecular weight of 234 to about 2000g/mol), and the like.

Further, an example of the chain transfer agent of Chemical Formula 1 may include hydroxy acid, specifically, alpha-hydroxy acid or beta-hydroxy acid. A specific example of the alpha-hydroxy acid may include glycolic acid, DL-lactic acid, D-lactic acid, L-lactic acid, citric acid, mandelic acid, and the like, and a specific example of the beta-hydroxy acid may include 3-hydroxy propionic acid, DL-3-hydroxybutyric acid, D-3-hydroxybutyric acid, L-3-hydroxybutyric acid, DL-3-hydroxy valeric acid, D-3-hydroxy valeric acid, L-3-hydroxy valeric acid, salicylic acid and salicylic acid derivatives, and the like.

Furthermore, a specific example of the chain transfer agent of Chemical Formula 1 may include biacids, more specifically, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, succinic acid, malonic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and the like.

The chain transfer agent of Chemical Formula 1 according to the exemplary embodiment of the present invention may be preferably a compound in which LH is -OH or -CO₂H; and a is an integer of 1 to 4.

In the chain transfer agent of Chemical Formula 1 according to the exemplary embodiment of the present invention, a is 1; LH is -OH or -CO₂H; J is -[CR⁵¹R⁵²]_n-CR⁵³R⁵⁴R⁵⁵, phenyl, or naphthyl; n is an integer of 0 to 20; and R⁵¹ to R⁵⁵ may be the same as or different from each other and be hydrogen, methyl, ethyl, propyl, or butyl.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, in the chain transfer agent of Chemical Formula 1, a is 2; LH(s) may be the same as or different from each other and be -OH or -CO₂H; J is -[CR⁵¹R⁵²]_n-, para-phenylene, metha-phenylene, ortho-phenylene, 2,6-naphthalendiyl, -CH₂CH₂N(R⁵⁶)CH₂CH₂-, or -[CH₂CH(R⁵⁶)O]_mCH₂CH(R)-; n is an integer of 1 to 20; R⁵¹, R⁵², and R⁵⁶ may be the same as or different from each other and be hydrogen, methyl, ethyl, propyl, or butyl; and m is an integer of 1 to 10.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, in the chain transfer agent of Chemical Formula 1, a is 3; LH is -CO₂H; and J is 1,2,3-propanetriyl, 1,2,3-benzenetriyl, 1,2,4-benzenetriyl, or 1,3,5-benzenetriyl.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, in the chain transfer agent of Chemical Formula 1, a is 4; LH is -CO₂H; and J is 1,2,3,4-butanetetrayl or 1,2,4,5-benzenetetrayl.

It is most preferable that as the chain transfer agent according to the exemplary embodiment of the present invention, methanol, acetic acid, adipic acid, succinic acid, and phthalic acid may be used alone or mixed with another chain transfer agent to thereby be used in plural.

As the cobalt (II) or chromium (II) catalyst including the salen ligand according to the exemplary embodiment of the present invention, any cobalt (II) or chromium (II) catalyst including a salen ligand known in the art may be used, but a cobalt (II) or chromium (II) catalyst including the salen ligand represented by the following Chemical Formula 2 or 3 may be preferably used.

[Chemical Formula 2]

In Chemical Formula 2,

M is cobalt (II) or chromium (II);

A is an oxygen or sulfur atom;

Q is a diradical linking two nitrogen atoms;

R', R'', and R''' are each independently hydrogen; halogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; (C6-C20)arylcarbonyl; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl; and

two of R', R'', and R''' may be linked to each other to form a ring, and the formed ring may be further substituted with at least one selected from a group consisting of halogen; cyano; nitro; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; and (C6-C20)arylcarbonyl.

[Chemical Formula 3]

In Chemical Formula 3,

M is cobalt (II) or chromium (II);

A is an oxygen or sulfur atom;

Q is a diradical linking two nitrogen atoms;

two of R¹ to R¹⁰ may be linked to each other to form a ring;

[Chemical Formula a]

[Chemical Formula b]

[Chemical Formula c]

Z is a nitrogen or phosphorus atom;

R⁴¹, R⁴², and R⁴³ are each independently hydrogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl; two of R⁴¹, R⁴², and R⁴³ are linked to each other to form a ring;

X' is an oxygen atom, a sulfur atom, or N-R (here, R is (C1-C20)alkyl);

a nitrogen atom of imine is coordinated with or de-coordinated from M.

In the cobalt (II) or chromium (II) catalyst including the salen ligand of Chemical Formula 2 or 3, Q is a divalent group capable of having two radicals to thereby be bonded to two nitrogen atoms and any divalent group may be used without limitation as long as it has a structure capable of linking two nitrogen atoms to each other. Preferably, Q may be a (C1-C30)hydrocarbon diradical with or without at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom, more specifically, (C1-C20)alkylene, (C2-C20)alkenylene, (C2-C20)alkinylene, (C3-C20)cycloalkylene, or (C6-C30)arylene, wherein the alkylene, alkenylene, cycloalkylene, and arylene may include or not include at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom. More preferably, Q is trans-1,2-cyclohexylene, phenylene, or ethylene.

Further, in the catalyst of Chemical Formula 2, R'' and R''' may be linked to each other to form an aromatic ring, and the formed aromatic ring may be further substituted with at least one selected from a group consisting of halogen; cyano; nitro; (C1-C20)alkyl; (C1-C20)alkyl substituted with a halogen atom; (C1-C20)alkyl(C6-C20)aryl; (C6-C20)aryl(C1-C20)alkyl; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; and (C6-C20)arylcarbonyl.

Further, in the catalyst of Chemical Formula 3, more preferably, R¹ to R¹⁰ are each independently hydrogen, halogen, (C1-C20)alkyl, (C2-C20)alkenyl, (C1-C20)alkyl(C6-C20)aryl, (C6-C20)aryl(C1-C20)alkyl, (C1-C20)alkoxy, (C6-C30)aryloxy, formyl, (C1-C20)alkylcarbonyl, (C6-C20)arylcarbonyl, or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl, at least one of R¹ to R⁸ is -[YR⁴⁴ _3-a{(CR⁴⁵R⁴⁶)_bN⁺R²¹R²²R²³}_a], Y is C or Si, R⁴⁴,R⁴⁵,R⁴⁶,R²¹,R²², and R²³ each independently hydrogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; or a metalloid radical of Group 14 metal substituted with hydrocarbyl, two of R²¹, R²², and R²³ may be linked with each other to form a ring; a is an integer of 1 to 3, and b is an integer of 1 to 20; and n, which is the total number of quaternary ammonium salt included in R¹ to R⁸, is a positive integer.

In addition, in the catalyst of Chemical Formula 3, more preferably, each X^- is independently a halide ion; HCO₃ ^-; BF₄ ^-; ClO₄ ^-; NO₃ ^-; PF₆ ^-; (C6-C20)aryloxy anion; (C6-C20)aryloxy anion substituted with nitro; (C1-C20)alkylcarboxy anion; (C6-C20)arylcarboxy anion; (C1-C20)alkoxy anion; (C1-C20)alkylcarbonate anion; (C6-C20)arylcarbonate anion; (C1-C20)alkylsulfonate anion; (C1-C20)alkylamido anion; (C6-C20)arylamido anion; (C1-C20)alkylcarbamate anion; or (C6-C20)arylcarbamate anion.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, the epoxide compound may be at least one selected from a group consisting of (C2-C20)alkyleneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, or (C6-C20)aryl(C1-C20)alkyloxy; (C4-C20)cycloalkyleneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, or (C6-C20)aryl(C1-C20)alkyloxy; and (C8-C20)styreneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, (C6-C20)aryl(C1-C20)alkyloxy, or (C1-C20)alkyl.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, a specific example of the epoxide compound may include ethylene oxide, propylene oxide, butene oxide, pentene oxide, hexene oxide, octene oxide, decene oxide, dodecene oxide, tetradecene oxide, hexadecene oxide, octadecene oxide, butadiene monoxide, 1,2-epoxide-7-octene, epifluorohydrin, epichlorohydrin, epibromohydrin, isopropyl glycidyl ether, butyl glycidyl ether, t-butyl glycidyl ether, 2-ethylhexyl glycidyl ether, allyl glycidyl ether, cyclopentene oxide, cyclohexene oxide, cyclooctene oxide, cyclododecene oxide, alpha-pinene oxide, 2,3-epoxide norbonene, limonene oxide, dieldrin, 2,3-epoxidepropylbenzene, styrene oxide, phenylpropylene oxide, stilbene oxide, chlorostilbene oxide, dichlorostilbene oxide, 1,2-epoxy-3-phenoxypropane, benzyloxymethyl oxirane, glycidyl-methylphenyl ether, chlorophenyl-2,3-epoxidepropyl ether, epoxypropyl methoxyphenyl ether, biphenyl glycidyl ether, glycidyl naphthyl ether, and the like.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, bulk polymerization may be performed using the epoxide compound itself as a solvent, or a solvent may be further included as a reaction medium to thereby be used in polymerization. That is, in step 1), the solvent may be further put into the reactor. In this case, activity deterioration according to viscosity at the time of polymerization reaction may be suppressed by putting the solvent into the reactor, and it may be easy to control a catalyst quenching and separation process after the reaction is completed.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, the solvent may be at least one selected from a group consisting of aromatic hydrocarbons, halogenated hydrocarbons, ethers, and esters. As a specific example, one or a combination of at least two of the aromatic hydrocarbons, such as benzene, toluene, xylene, and the like, the halogenated hydrocarbons such as chloromethane, methylenechloride, chloroform, carbon tetrachloride, 1,1-dichloroethane, 1,2-dichloroethane, ethylchloride, trichloroethane, 1-chloropropane, 2-chloropropane, 1-chlorobutane, 2-chlorobutane, 1-chloro-2-methylpropane, chlorobenzene, bromobenze, and the like, the ethers such as tetrahydrofuran, diethylether, diphenylether, dioxane, and the like, and the esters such as ethyl acetate, butyl acetate, methyl benzoate, and the like, may be used.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, it is most preferable that the solvent may be at least one selected from a group consisting of toluene, dichloromethane, dichloroethane, tetrahydrofuran, and ethylacetate.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, pressure of carbon dioxide in step 2) may be atmospheric pressure to 100 atm. Preferably, the pressure may be 5 to 30 atm. An internal temperature of the reactor after injecting carbon dioxide, that is, a polymerization temperature may be 100℃ or less, preferably 20 to 100℃, more preferably 20 to 60℃, and the polymerization may be performed for 5 to 20 hours.

In the method for preparing polycarbonate according to the exemplary embodiment of the present invention, a molar ratio of the epoxide compound : the divalent catalyst (Chemical Formula 2 or 3) may be 100:1 to 1,000,000:1, preferably 100:1 to 50,000:1. The epoxide compound may be used as the solvent simultaneously with a polymerization reactant, but in the case in which the molar ratio of the epoxide compound to the divalent catalyst is out of the above-mentioned range, a concentration of the reactant is significantly diluted, such that a polymerization activity of the catalyst may be deteriorated.

Hereinafter, a configuration and an effect of the present invention will be described in more detail with reference to specific Examples and Comparative Examples, but they are provided only for clearly understanding of the present invention and not for limiting the scope of the present invention.

[Preparation Example 1]

A catalyst 1 was prepared according to a method described in J. Am. Chem. Soc. 2002, 124, 1307 and used. A catalyst 2 was prepared according to Korean Patent B1 0853358 and used.

[Example 1] Catalyst 1 In-situ oxidation and Polymerization

Propylene oxide (10mL), a catalyst 1 (43 mg), bis(triphenylphospho-ranylidene)ammonium chloride (PPNCl, 41mg), and adipic acid (104mg) as a chain transfer agent were put into a 50mL reactor (stainless bomb reactor), and then the reactor was assembled. After injecting air having a pressure of 10 bar, the mixture was stirred at room temperature for 2 hours. Then, carbon dioxide having a pressure of 20 bar was additionally injected and stirred for 41 hours. After the reaction was finished, the reactor was cooled, and the reaction was terminated by removing gas pressure of carbon dioxide and air. Malonic acid was added to the obtained viscous solution, thereby preventing decomposition of the produced polymer. A conversion rate of the reactant and selectivity for polymer formation were calculated through proton nuclear magnetic resonance (¹H-NMR) spectroscopy. A molecular weight of the produced polymer was measured using gel permeation chromatography (GPC). The results were shown in the following Table 1.

[Example 2] Catalyst 2 In-situ oxidation and Polymerization

Propylene oxide (10mL), a catalyst 2 (48.5mg), adipic acid (626mg) as a chain transfer agent, and toluene (10mL) as a solvent were put into a 50mL reactor (stainless bomb reactor), and then the reactor was assembled. After injecting air having a pressure of 10 bar, the mixture was stirred at room temperature for 2 hours. Carbon dioxide having a pressure of 20 bar was additionally injected and stirred for 15 hours while maintaining a temperature in the reactor at 50℃. In this case, a total pressure of the reactor was 30 bar. After the reaction was finished, the reactor was cooled, and the reaction was terminated by removing gas pressure of carbon dioxide and air. Malonic acid was added to the obtained viscous solution, thereby preventing decomposition of the produced polymer. A conversion rate of the reactant and selectivity for polymer formation were calculated through proton nuclear magnetic resonance (¹H-NMR) spectroscopy. A molecular weight of the produced polymer was measured using gel permeation chromatography (GPC). The results were shown in the following Table 1.

[Comparative Example 1] Catalyst 1 In-situ oxidation and Polymerization

An experiment was performed by the same method in Example 1 except for not using the chain transfer agent, and the results were shown in the following Table 1.

Table 1

Example	Catalyst	PO/Catalyst	Chain transfer agent	Reaction		PO conversion rate/Selectivity
Example	Catalyst	PO/Catalyst	Chain transfer agent	Temperature(℃)	time	PO conversion rate/Selectivity
Example 1	1	2000/1	Adipic acid (10eq)	RT	41h	26%/83%
Example 2	2	5000/1	Adipic acid (150eq)	50	15h	90%/97%
Comparative Example 1	1	2000/1	X	RT	21h	-

It may be appreciated from the results in Table 1 that polymerization may be performed simultaneously with preparing the catalyst having a catalytic activity from the divalent catalyst not having the catalytic activity by in-situ oxidation, and particularly, in the case of the catalyst 2 in Example 2, polycarbonate may be prepared with high conversion rate and selectivity when the molar ratio of propylene oxide to the catalyst was 5000:1. On the other hand, in the case of Comparative Example1, even in the case of using the catalyst 1 that is the same divalent catalyst as that in Example 1, the chain transfer agent was not used, such that polycarbonate was not prepared.

Therefore, it may be appreciated that in order to enable the polymerization simultaneously with preparing the catalyst having the catalytic activity from the divalent catalyst not having the catalytic activity through in-situ oxidation, it was necessary to use the chain transfer agent.

[Example 3] Propylene oxide conversion rate depending on solvent

Propylene oxide (10mL), a catalyst 2 (118mg), adipic acid (626mg) as a chain transfer agent, and a solvent (10mL) as shown in the following Table 2 were put into a 50mL reactor (stainless bomb reactor), and then the reactor was assembled. After injecting air having a pressure of 10 bar, the mixture was stirred at room temperature for 2 hours. Then, carbon dioxide having a pressure of 20 bar was additionally injected and stirred for 15 hours while maintaining a temperature in the reactor at a predetermined temperature. After the reaction was finished, the reactor was cooled, and the reaction was terminated by removing pressure of carbon dioxide. Malonic acid was added to the obtained viscous solution, thereby preventing decomposition of the produced polymer. A conversion rate of the reactant and selectivity for polymer formation were calculated through proton nuclear magnetic resonance (¹H-NMR) spectroscopy. A molecular weight of the produced polymer was measured using gel permeation chromatography (GPC). The results were shown in the following Table 2.

[Examples 4 to 6]

Experiments were performed by the same method as in Example 3, and effects depending on various solvents were shown in the following Table 2.

Table 2

Example	Solvent	PO/catalyst	Temperature(℃)	Pressure	Time	PO conversion rate/Selectivity	Mw/Mn	PDI
3	DCE	2000:1	50	20bar	15h	>99% / 86%	2172/1871	1.16
4	Toluene	2000:1	50	20bar	15h	>99% / 88%	2509/2294	1.09
5	THF	2000:1	50	20bar	15h	99% / 89%	2448/2247	1.09
6	EA	2000:1	50	20bar	15h	>99% / 89%	2459/2249	1.09

[Example 7] Propylene oxide conversion rate depending on catalyst equivalent

Propylene oxide (10mL), a catalyst 2 (60mg), adipic acid (626mg) as a chain transfer agent, and dichloromethane (10mL) were put into a 50mL reactor (stainless bomb reactor), and then the reactor was assembled. After injecting air having a pressure of 10 bar, the mixture was stirred at room temperature for 2 hours. Carbon dioxide having a pressure of 20 bar was additionally injected at room temperature and stirred for 5 hours while maintaining a temperature in the reactor at 50℃. After the reaction was finished, the reactor was cooled, and the reaction was terminated by removing pressure of carbon dioxide. Malonic acid was added to the obtained viscous solution, thereby preventing decomposition of the produced polymer. A conversion rate of the reactant and selectivity for polymer formation were calculated through proton nuclear magnetic resonance (¹H-NMR) spectroscopy. A molecular weight of the produced polymer was measured using gel permeation chromatography (GPC). The results were shown in the following Table 3.

[Examples 8 to 11] Propylene oxide conversion rate depending on catalyst equivalent

Effects depending on the solvent, the catalyst equivalent, and the temperature were measured by the same method as in Example 7 and shown in the following Table 3.

Table 3

Example	Solvent	PO/catalyst	Temperature(℃)	Pressure	Time	PO conversion rate/ Selectivity	Mn	PDI
7	DCM	4000:1	50	20bar	5h	75% / 99%	2103	1.15
8	Toluene	4000:1	50	20bar	5h	89% / 99%	2305	1.16
9	Toluene	5000:1	50	20bar	15h	98% / 96%	2294	1.09
10	Toluene	5000:1	70	20bar	15h	48% / 47%	1863	1.09
11	Toluene	10000:1	50	20bar	15h	76% / 96%	2249	1.09

[Example 12] Reactivity depending on presence and absence of solvent

Propylene oxide (10mL), a catalyst 2 (48.5mg), adipic acid (626mg) as a chain transfer agent, and a solvent (10mL) were put into a 50mL reactor (stainless bomb reactor), and then the reactor was assembled. After injecting air having a pressure of 10 bar, the mixture was stirred at room temperature for 2 hours. Then, carbon dioxide having a pressure of 20 bar was additionally injected and stirred for 15 hours while maintaining a temperature in the reactor at 50℃. After the reaction was finished, the reactor was cooled, and the reaction was terminated by removing pressure of carbon dioxide. Malonic acid was added to the obtained viscous solution, thereby preventing decomposition of the produced polymer. A conversion rate of the reactant and selectivity for polymer formation were calculated through proton nuclear magnetic resonance (¹H-NMR) spectroscopy. A molecular weight of the produced polymer was measured using gel permeation chromatography (GPC). The results were shown in the following Table 4.

[Examples 13 to 16] Reactivity depending on presence and absence of solvent

Experiments were performed by the same method as in Example 12, and effects depending on a use amount of the solvent were shown in the following Table 4.

Table 4

Example	PO/Catalyst	Toluene	PO conversion rate (%)	PPC diol selectivity (%)
12	5000:1	10 mL	98	95
13	5000:1	5 mL	99	94
14	5000:1	2 mL	90	90
15	5000:1	0	96	86
16	10000:1	X (PO 20mL)	90	86

Although the exemplary embodiments of the present invention have been disclosed in detail, those skilled in the art will appreciate that various modifications are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims. Accordingly, such modifications of the embodiment of the present invention should also be understood to fall within the scope of the present invention.

Claims

A method for preparing polycarbonate, the method comprising:

1) putting epoxide compound, a cobalt (II) or chromium (II) catalyst including a salen ligand, and a chain transfer agent into a reactor and injecting air thereinto; and

2) injecting carbon dioxide to the reactor to polymerize epoxide and carbon dioxide.
The method of claim 1, wherein the epoxide compound is at least one selected from a group consisting of (C2-C20)alkyleneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, or (C6-C20)aryl(C1-C20)alkyloxy; (C4-C20)cycloalkyleneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, or (C6-C20)aryl(C1-C20)alkyloxy; and (C8-C20)styreneoxide substituted or unsubstituted with halogen, (C1-C20)alkyloxy, (C6-C20)aryloxy, (C6-C20)aryl(C1-C20)alkyloxy, or (C1-C20)alkyl.
The method of claim 1, wherein the chain transfer agent is represented by the following Chemical Formula 1.

[Chemical Formula 1]

J(LH)_a

[In Chemical Formula 1, J is an a-valent hydrocarbyl radical having 1 to 60 carbon atoms with or without an ether, ester, or amine group; each LH is independently -OH, -CO₂H, -C(OR^z)OH, -OC(R^z)OH, -NHR^z, -NHC(O)R^z, -NHC=NR^z, -NR^zC=NH, -NR^zC(NR^z ₂)=NH, -NHC(NR^z ₂)=NR^z, -NHC(O)OR^z, -NHC(O)NR^z ₂, -C(O)NHR^z, -C(S)NHR^z, -OC(O)NHR^z, -OC(S)NHR^z, -SH, -C(O)SH, -B(OR^z)OH, -P(O)_b(R^z)_c(OR^z)_d(O)_eH, -OP(O)_b(R^z)_c(OR^z)_d(O)_eH, -N(R^z)OH, -ON(R^z)H, =NOH, or =NN(R^z)H; each R^z is independently hydrogen, (C1-C20)alkyl, (C3-C20)cycloalkyl, (C1-C20)heteroaliphatic alkyl, 3- to 12-membered heterocyclic, or (C6-C12)aryl; a is an integer of 1 to 10, when a is 2 or more, LH(s) is the same as or different from each other; and b and c are each independently 0 or 1, d is 0, 1, or 2, e is 0 or 1, and a sum of b, c, and d is 1 or 2.]
The method of claim 3, wherein in Chemical Formula 1, LH is -OH or -CO₂H; and a is an integer of 1 to 4.
The method of claim 1, wherein the cobalt (II) or chromium (II) catalyst including the salen ligand is represented by the following Chemical Formula 2.

[Chemical Formula 2]

[In Chemical Formula 2,

M is cobalt (II) or chromium (II);

A is an oxygen or sulfur atom;

Q is a diradical linking two nitrogen atoms;

R', R'' and R''' are each independently hydrogen; halogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; (C6-C20)arylcarbonyl; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl; and

two of R', R'' and R''' may be linked to each other to form a ring, and the formed ring is further substituted with at least one selected from a group consisting of halogen; cyano; nitro; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; and (C6-C20)arylcarbonyl.]
The method of claim 1, wherein the cobalt (II) or chromium (II) catalyst including the salen ligand is represented by the following Chemical Formula 3.

[Chemical Formula 3]

[In Chemical Formula 3,

M is cobalt (II) or chromium (II);

A is an oxygen or sulfur atom;

Q is a diradical linking two nitrogen atoms;

R¹ to R¹⁰ are each independently hydrogen; halogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy; (C6-C30)aryloxy; formyl; (C1-C20)alkylcarbonyl; (C6-C20)arylcarbonyl; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl;

two of R¹ to R¹⁰ may be linked to each other to form a ring;

at least one of the hydrogens contained in R¹ to R¹⁰ and Q is substituted with a proton group selected from a group consisting of Chemical Formulas a, b, and c:

[Chemical Formula a]

[Chemical Formula b]

[Chemical Formula c]

each X^- is independently a halide ion; HCO₃ ^-; BF₄ ^-; ClO₄ ^-; NO₃ ^-; PF₆ ^-; (C6-C20)aryloxy anion; (C6-C20)aryloxy anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkylcarboxyl anion; (C1-C20)alkylcarboxyl anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)arylcarboxyl anion; (C6-C20)arylcarboxyl anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkoxy anion; (C1-C20)alkoxy anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and an phosphorus atom; (C1-C20)alkylcarbonate anion; (C1-C20)alkylcarbonate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)arylcarbonate anion; (C6-C20)arylcarbonate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkylsulfonate anion; (C1-C20)alkylsulfonate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkylamido anion; (C1-C20)alkylamido anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)arylamido anion; (C6-C20)arylamido anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkylcarbamate anion; (C1-C20)alkylcarbamate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; or (C6-C20)arylcarbamate anion; and (C6-C20)arylcarbamate anion containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom;

Z is a nitrogen or phosphorus atom;

R²¹, R²², R²³, R³¹, R³², R³³, R³⁴, and R³⁵ are each independently (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl; and two of R²¹, R²², and R²³ or two of R³¹, R³², R³³, R³⁴, and R³⁵ may be linked to each other to form a ring;

R⁴¹, R⁴², and R⁴³ are each independently hydrogen; (C1-C20)alkyl; (C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C2-C20)alkenyl; (C2-C20)alkenyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C1-C20)alkyl(C6-C20)aryl; (C1-C20)alkyl(C6-C20)aryl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; (C6-C20)aryl(C1-C20)alkyl; (C6-C20)aryl(C1-C20)alkyl containing at least one of a halogen atom, a nitrogen atom, an oxygen atom, a silicon atom, a sulfur atom, and a phosphorus atom; or a metalloid radical of Group 14 metal substituted with (C1-C20)alkyl or (C6-C20)aryl; two of R⁴¹, R⁴², and R⁴³ may be linked to each other to form a ring;

X' is an oxygen atom, a sulfur atom, or N-R (here, R is (C1-C20)alkyl);

n, which is a total number of proton groups contained in R¹ to R¹⁰ and Q is a positive integer; and

a nitrogen atom of imine is coordinated with or de-coordinated from M.]
The method of claim 3, wherein in Chemical Formula 1, a is 1; LH is -OH or -CO₂H; J is -[CR⁵¹R⁵²]_n-CR⁵³R⁵⁴R⁵⁵, phenyl, or naphthyl; n is an integer of 0 to 20; and R⁵¹ to R⁵⁵ are the same as or different from each other and are hydrogen, methyl, ethyl, propyl, or butyl.
The method of claim 3, wherein in Chemical Formula 1, a is 2; LH(s) is the same as or different from each other and is -OH or -CO₂H; J is -[CR⁵¹R⁵²]_n-, para-phenylene, metha-phenylene, ortho-phenylene, 2,6-naphthalendiyl, -CH₂CH₂N(R⁵⁶)CH₂CH₂-, or -[CH₂CH(R⁵⁶)O]_mCH₂CH(R)-; n is an integer of 1 to 20; R⁵¹, R⁵², and R⁵⁶ are the same as or different from each other and are hydrogen, methyl, ethyl, propyl, or butyl; and m is an integer of 1 to 10.
The method of claim 3, wherein in Chemical Formula 1, a is 3; LH is -CO₂H; and J is 1,2,3-propanetriyl, 1,2,3-benzenetriyl, 1,2,4-benzenetriyl, or 1,3,5-benzenetriyl.
The method of claim 3, wherein in Chemical Formula 1, a is 4; LH is -CO₂H; and J is 1,2,3,4-butanetetrayl or 1,2,4,5-benzenetetrayl.
The method of claim 1, wherein in step 1), a solvent is further put into the reactor.
The method of claim 11, wherein the solvent is at least one selected from a group consisting of aromatic hydrocarbons, halogenated hydrocarbons, ethers, and esters.
The method of claim 12, wherein the solvent is at least one selected from a group consisting of toluene, dichloromethane, dichloroethane, tetrahydrofuran, and ethylacetate.
The method of claim 1, wherein a molar ratio of the epoxide compound : the cobalt (II) or chromium (II) catalyst including the salen ligand is 100:1 to 1,000,000:1.