In order to combine the properties of polymers based on vinylidene chloride (VC2) (barrier properties towards many gases) and fluorinated polymers (low surface energy, improvement of the chemical resistance), a diblock terpolymer poly(VC2-CO-MA)-b-(PFDA) was synthesized by RAFT process. The first block is a statistical copolymer of vinylidene chloride (VC2) and methyl acrylate (MA) (M-n = 6800 g mol(-1) and PDI= 1.4), the second block is a homopolymer of 1H,1H,2H,2H-perfluorodecyl acrylate (FDA). The diblock terpolymer, when used in a coating formulation based on a poly(VC2-co-MA) matrix, migrates towards the surface of the coating and fluorinated moieties are located at the surface. The migration of the additive was clearly shown by scanning electron microscopy EDX and by measurements of surface energy, and the influence of the nature of the solvents used to prepare the coating was clearly established. These results indicate that the driving force for the migration is the surface energy of the additive. © 2005 Elsevier Ltd. All rights reserved.