Amphiphilic diblock copolymers comprising polyethylene glycol (PEG) and 1-vinyl imidazole (VIM) were synthesized using reversible addition–fragmentation chain transfer (RAFT) polymerization. The study focused on the synthesis of well-defined nanostructures with tunable composition and their functional modification for biomedical applications. The successful polymerization of PEG-b-PVIM diblock copolymers was confirmed via ¹H NMR spectroscopy, and their molecular weights were analyzed using gel permeation chromatography (GPC). The copolymers exhibited pH-responsive behavior, with effective pK values of approximately 4.2. To facilitate radiolabeling and in vivo tracking, a post-polymerization modification enabled the conjugation of a 1,4,7-Triazacyclononane-1,4,7-triacetic acid (NOTA) chelator via aminolysis. The final conjugates were purified and characterized, confirming successful functionalization. These findings highlight the potential of PEG_x-b-PVIM_y diblock copolymers for biomedical applications.