Modifier, modified and conjugated diene-based polymer and rubber composition including the same

A method for preparing a modified and conjugated diene-based polymer, the method comprising:

• a modification step of reacting a conjugated diene-based polymer comprising an organometal part activated from a lanthanide series rare earth element catalyst composition with a modifier comprising a compound represented by Formula 1:
• wherein,
• R1 to R3 are each independently a trivalent hydrocarbon group which is substituted with at least one substituent selected from the group consisting of a halogen group, an alkyl group of 1 to 20 carbon atoms, a cycloalkyl group of 3 to 20 carbon groups, an aryl group of 6 to 30 carbon atoms, and —R6COOR7;
• or an unsubstituted divalent hydrocarbon group of 1 to 10 carbon atoms,
• wherein all R1 to R3 are not the trivalent hydrocarbon group;
• or the divalent hydrocarbon group, at the same time,
• R4 is a single bond, an alkylene group of 1 to 20 carbon atoms, or a cycloalkylene group of 3 to 20 carbon atoms,
• R5 is a silyl group which is unsubstituted or substituted with an alkyl group of 1 to 20 carbon atoms;
• halogen;
• a cyano group;
• or —COR8,
• R6 is a single bond, an alkylene group of 1 to 20 carbon atoms, or a cycloalkylene group of 3 to 20 carbon atoms,
• R7 is an alkyl group of 1 to 20 carbon atoms, or a cycloalkyl group of 3 to 20 carbon atoms, and
• R8 is one selected from the group consisting of an alkoxy group of 1 to 10 carbon atoms, an aryl group of 6 to 30 carbon atoms, a heteroaryl group of 2 to 30 carbon atoms, a heterocycloalkyl group of 2 to 10 carbon atoms, a heteroamine group of 2 to 10 carbon atoms, and a disilylamino group of 3 to 10 carbon atoms.