The present invention relates to new impact modifiers and a process for making these new impact modifiers and their use in polymeric compositions. More particularly the present invention relates to a new polymeric impact modifier with a core-shell structure made by a multistage polymerization process comprising at least one gradient polymer. The present invention relates as well to a process preparing such an impact modifier, especially its recovery process after the end of the polymerization. The present invention also relates to a thermoplastic composition comprising the new impact modifier.