Controlling perfluoropolyalkylether rearrangements at the surface of photocured networks

Perfluoropolyalkylether (PFPAE) reactive macromers can be used in very low concentration (≤2 wt%) as efficient surface modifying agents of epoxy resins to obtain hydrophobic photocured copolymers. However, the hydrophobicity achieved thanks to the spontaneous migration of the PFPAE chains to the free surface could be dramatically lost due to environmentally induced rearrangements of the fluorinated segments, even though they are chemically bonded to the polymer matrix. To preserve the coating performances of the photocured copolymers when exposed to various environments, different approaches have been investigated. In particular, to hinder the mobility of the fluorinated chains, the length of the fluorinated comonomer chain, the epoxy matrix stiffness, and the functional PFPAE end-groups have been tuned. Such strategies are demonstrated to inhibit or completely suppress the surface reconstruction of the copolymers when exposed to different surrounding environments (e.g., immersion in water or oil), allowing to obtain photocured films with a long-term and constant reduced surface energy of ≈20 mN/m