Application of rare-earth complexes chelated by tridentate carbazolyl in conjugated diene and polar monomer copolymerization catalyst system

The invention relates to application of rare-earth complexes chelated by tridentate carbazolyl in a conjugated diene and polar monomer copolymerization catalyst system. The catalyst system comprises the rare-earth complexes chelated by the tridentate carbazolyl, organic boron salt and an alkylation agent by the molar ratio ranging from 1:1:0 to 1:1:100. The catalyst system catalyzes copolymerization between conjugated diene and polar monomer; chain segment compositions and molecular weight of obtained copolymers can be regulated and controlled by changing molar ratio between two monomers and the catalyst system and the molar ratio between the two monomers; the molar ratio between a conjugated diene monomer and the catalyst system is 500-10000:1; and the molar ratio between the polar monomer and the catalyst system is 100-10000:1.The content of segmental cis 1,4 of poly-conjugated-diene of the obtained copolymers ranges from 97% to 99.9%, number-average molecular weight is within the range from 5 to 2 million, and molecular weight distribution is smaller than 3.0.