[zhaozhguo]

Dear my friends,
  Although there are a lot of papers to describe the special properties of fluorine-containing materials. I still have my question: why fluorinated chain easily crystallize and why fluorinated chain tending to repel both water and oil.
  Information like follows I believe is just description and not a clear explanation.
  with –CF3 groups from the side chains aligned on the surface, through side chain crystallization. The surface –CF3 groups give coatings with an extremely low surface energy, down to 8 dyn/cm. Such surfaces are not only water repellent but are also oleophobic (oil-repellent). As such, they are useful for fabric treatments, as anti-graffiti coatings, and in kitchen and industrial workplace applications.

[Corribus]

My guess: Fluorinated hydrocarbons have reduced van der Waals interactions (London dispersion forces), which lowers their force of interaction with other nearby substances at the molecular level.