Catalytic system for conjugated diene polymerisation, polymerisation method and functional polymer obtained

A catalytic system for polymerization comprising:

• one rare-earth metal salt corresponding to the formula Ln(A′)3(B)n, in which:
• Ln is chosen from lanthanides, yttrium, or scandium;
• A′ is chosen from carboxylates, organophosphates, alcoholates, amides, alkyls or borohydrides;
• B is a solvent molecule complexed to the rare-earth metal;
• and
• n is an integer between 0 and 4;
• and
• one organometallic compound corresponding to the formula (I):
• wherein:
• M is a metal belonging to the 2nd or 13th column of the Periodic Table;
• R1, R2, R3, R4, which are identical to or different from one another, are hydrogen atoms or linear or branched alkyl or substituted or unsubstituted aryl substituents, optionally bonded together to form at least one ring composed of 5 or 6 atoms, or at least one aromatic ring;
• A is an alkyl radical based on C, H or Si atoms;
• X is a chemical function bonded by a heteroatom to (CH2)m in the formula (I);
• L is a Lewis base;
• x is an integer that is equal to 0, 1, 2, 3 or 4;
• n and m, independently of one another, are each an integer greater than or equal to 0, on condition that n and m are not both equal to 0;
• z is equal to 2 when M belongs to the 2nd column of the Periodic Table and is equal to 3 when M belongs to the 13th column of the Periodic Table;
• and
• y is a non-zero integer ranging from 1 to z.