Self-Assembling Comb-like Fluorinated Epoxy Acrylates for Low Surface Energy UV-Curable Coatings

Fluorinated UV-curable coatings typically rely on high fluorine loadings to achieve water repellency, which causes phase separation, high cost, and environmental concerns. Here, a novel UV-curable fluorinated epoxy acrylate (FEA) oligomer with a comb-like architecture bearing perfluorophenyl-terminated fluorinated side chains was synthesized to maximize fluorine efficiency. A mono-substituted fluorinated alcohol was prepared via nucleophilic aromatic substitution of hexafluorobenzene with octafluorohexanediol, and the FEA oligomer was constructed through a two-step urethane-forming reaction with diglycerol diacrylate (DGDA) and isophorone diisocyanate (IPDI). The chemical structures were confirmed by FT-IR and ¹H/¹⁹F NMR spectroscopy. UV-cured FEA/HDDA-F films exhibited high double-bond conversions of 93.5-97.9% and adequate thermal stability for coating applications. As the FEA content increased, the advancing water contact angle rose from 69° to 118°, and the surface free energy decreased from 34.0 to 19.2 mJ/m², comparable to that of polytetrafluoroethylene (18.5 mJ/m²). Remarkably, this performance was achieved at a lower overall fluorine content than the fluorinated diluent alone, and the near-zero polar component of the surface energy, together with XPS analysis and SEM-observed surface texturing, supports the proposed preferential segregation of the fluorinated side chains toward the air-film interface. The comb-like FEA is a promising fluorine-efficient material for UV-curable hydrophobic and self-cleaning coatings.