Star copolymer and use thereof as a viscosity improver

The present invention relates to a star copolymer (C) including at least 10 wt.% of units derived from styrene monomer and including arms that include a statistical copolymer (EP) including ethylene units and propylene units, and the method for preparing same. The invention also relates to the use thereof in lubricating compositions, in particular for improving the viscosity index, to the lubricating compositions thus obtained and to the uses thereof. 本发明涉及种星形共聚物(C)以及用于制备该星形共聚物的方法，该星形共聚物包括至少10wt％的苯乙烯单体衍生单元并且包括臂，该臂包括包含乙烯单元和丙烯单元的统计结构共聚物(EP)。本发明还涉及其在润滑组合物中的用途，特别是用于改进粘度指数，并且还涉及由此获得的润滑组合物及其用途。