Summary: A fluorine containing hyperbranched polymer was synthesized by modifying an aromatic‐aliphatic hyperbranched polyester with a semifluorinated alcohol via a Mitsunobu reaction and was subsequently used as an additive in cationic photopolymerization of an epoxy resin. The remaining OH groups of the fluorinated hyperbranched polymer interact with the polymeric carbocation through a chain‐transfer mechanism inducing an increase in the final epoxy conversion. The fluorinated HBP induces modification of bulk and surface properties, with an increase in Tg and surface hydrophobicity already reached at very low concentration. The HBFP additive can, therefore, protect the coatings from aggressive solvents, increases hardness, and allows the preparation of a low energy surface coating.
