A method for manufacturing a conjugated diene polymer that can increase the robustness of a polymerization reaction system is provided. Also, a conjugated diene polymer, with a high cis-1,4-bond content, that is manufactured by this method for manufacturing is provided. A method for manufacturing a conjugated diene polymer includes polymerizing a conjugated diene monomer using a polymerization catalyst composition including a rare earth element compound and a compound having a cyclopentadiene skeleton, and a conjugated diene polymer manufactured with this method for manufacturing has a cis-1,4-bond content of 95% or greater.

A method for manufacturing a conjugated diene polymer that can increase the robustness of a polymerization reaction system is provided. Also, a conjugated diene polymer, with a high cis-1,4-bond content, that is manufactured by this method for manufacturing is provided. A method for manufacturing a conjugated diene polymer includes polymerizing a conjugated diene monomer using a polymerization catalyst composition including a rare earth element compound and a compound having a cyclopentadiene skeleton, and a conjugated diene polymer manufactured with this method for manufacturing has a cis-1,4-bond content of 95% or greater.

This disclosure is to provide a method for preparing a terminal-modified conjugated diene polymer which achieves an extremely high compounding amount of cis-1,4 without complicated preparing conditions, a terminal-modified conjugated diene polymer obtained via the method, a rubber composition containing the terminal-modified conjugated diene polymer, and a tire using the rubber composition. This disclosure is A method for preparing a terminal-modified conjugated diene polymer comprising: polymerizing a conjugated diene compound by using a polymerization catalyst composition and modifying a polymer obtained via the polymerization by using a modifier, wherein the polymerization catalyst composition contains a rare earth element compound, and a coordination compound having a cyclopentadiene skeleton selected from substituted or unsubstituted cyclopentadienes, substituted or unsubstituted indenes, and substituted or unsubstituted fluorenes, and wherein the polymerization and modification is performed in a one-pot way.

This disclosure is to provide a method for preparing a terminal-modified conjugated diene polymer which achieves an extremely high compounding amount of cis-1,4 without complicated preparing conditions, a terminal-modified conjugated diene polymer obtained via the method, a rubber composition containing the terminal-modified conjugated diene polymer, and a tire using the rubber composition. This disclosure is A method for preparing a terminal-modified conjugated diene polymer comprising: polymerizing a conjugated diene compound by using a polymerization catalyst composition and modifying a polymer obtained via the polymerization by using a modifier, wherein the polymerization catalyst composition contains a rare earth element compound, and a coordination compound having a cyclopentadiene skeleton selected from substituted or unsubstituted cyclopentadienes, substituted or unsubstituted indenes, and substituted or unsubstituted fluorenes, and wherein the polymerization and modification is performed in a one-pot way.

A method for preparing a functionalized polymer, the method comprising the steps of preparing a reactive polymer and reacting the reactive polymer with a heterocyclic nitrile compound.

A method for preparing a functionalized polymer, the method comprising the steps of preparing a reactive polymer and reacting the reactive polymer with a heterocyclic nitrile compound.

A method for preparing a functionalized polymer, the method comprising the steps of preparing a reactive polymer and reacting the reactive polymer with a heterocyclic nitrile compound.

A process for preparing a blend of trans-1,4-polybutadiene and syndiotactic 1,2-polybutadiene, the process comprising the steps of (i) polymerizing 1,3-butadiene in the presence of a lanthanide-based catalyst to form a polymerization mixture including trans-1,4-polybutadiene, where the lanthanide-based catalyst includes (a) a lanthanide-containing compound, and (b) an organomagnesium compound; and (ii) polymerizing 1,3-butadiene in the presence of an iron-based catalyst within the polymerization mixture including trans-1,4-polybutadiene to form syndiotactic 1,2-polybutadiene within the polymerization mixture including trans-1,4-polybutadiene and thereby produce a blend of trans-1,4-polybutadiene and syndiotactic 1,2-polybutadiene; where the iron-based catalyst includes (a) an iron-containing compound, (b) an organomagnesium compound, and (c) a silyl phosphonate.

A process for preparing a blend of trans-1,4-polybutadiene and syndiotactic 1,2-polybutadiene, the process comprising the steps of (i) polymerizing 1,3-butadiene in the presence of a lanthanide-based catalyst to form a polymerization mixture including trans-1,4-polybutadiene, where the lanthanide-based catalyst includes (a) a lanthanide-containing compound, and (b) an organomagnesium compound; and (ii) polymerizing 1,3-butadiene in the presence of an iron-based catalyst within the polymerization mixture including trans-1,4-polybutadiene to form syndiotactic 1,2-polybutadiene within the polymerization mixture including trans-1,4-polybutadiene and thereby produce a blend of trans-1,4-polybutadiene and syndiotactic 1,2-polybutadiene; where the iron-based catalyst includes (a) an iron-containing compound, (b) an organomagnesium compound, and (c) a silyl phosphonate.

The present invention provides a catalyst composition including a functionalizing agent of the following Formula 1 together with a rare earth metal compound, an alkylating agent, and a halogen compound, having good catalytic activity and polymerization reactivity and useful for the preparation of a conjugated diene-based polymer having high linearity and excellent processability, and a conjugated diene-based polymer prepared using the catalyst composition.

(X.sub.1).sub.aSi(X.sub.2).sub.4-a,[Formula 1]

In Formula 1, a, X.sub.1, and X.sub.2 are the same as defined in the disclosure.