Polylysine‐b‐p[HPMA] blockcopolymers containing a redox‐responsive disulfide bond between both blocks are synthesized by RAFT polymerization of pentafluorphenyl‐methacrylate with a macro‐CTA from Nϵ‐benzyloxycarbonyl (Cbz) protected polylysine (synthesized by NCA polymerization). This polylysine‐b‐p[PFMA] precursor blockcopolymer is converted to polylysine(Cbz)‐b‐p[HPMA] by postpolymerization modification