Incompletely condensed, fluorinated polyhedral oligomeric silsesquioxane with the highly reactive group of trisodium silanolate was used for the synthesis of an initiator for atom transfer radical polymerization. The initiator was applied to solution polymerization of methyl methacrylate (MMA) in the presence of a copper complex. The polymerization proceeded in a living fashion, providing tadpole-shaped polymers with an "inorganic head" of polyhedral oligomeric silsesquioxane (POSS) and an "organic tail" of well-defined PMMA. A blend film composed of the tadpole-shaped polymer and a matrix PMMA was annealed at 180degreesC for 5 days and then analyzed by neutron reflectometry, X-ray photoelectron spectroscopy, and contact angle measurement. These analyses revealed that the tadpole-shaped polymer was preferentially populated at the air/polymer interface, and the outermost layer of the film was almost completely covered by the POSS heads. This was mainly due to the low surface free energy of the fluorinated POSS moiety. Owing to this unique structure, the blend film showed strong resistance against Ar+ ion etching, despite the overall POSS content was only 2 wt %.