A process for manufacturing a dispersion of a vinylidene fluoride (VDF) thermoplastic polymer [polymer (F)], said process includes polymerizing VDF in an aqueous phase that includes: at least one surfactant selected from the group consisting of non-fluorinated surfactants [surfactant (HS)] and fluorinated surfactants having a molecular weight of less than 400 [surfactant (FS)]; and at least one functional (per)fluoropolyether (functional PFPE) comprising at least one (per)fluoropolyoxyalkylene chain [chain (R′F)] and at least one functional group, said functional PFPE having a number average molecular weight of at least 1000 and a solubility in water of less than 1% by weight at 25° C., wherein said functional PFPE is present in the aqueous phase in an amount of 0.001 to 0.3 g/l.