  We demonstrate that tunable superoleophobic surfaces fabricated by a simple
spin and spray coating methods of titania on silicon (Si) wafers and stainless
steel (SS) mesh, which possess a hierarchical re-entrant structure consisting
of nano meter sized particles on top of micron sized particle, are able to
induce superoleophobicity on an oleophilic self assembled monolayer of
1H,1H,2H,2H-perflurodecyltrichlorosilane (FDTS). Though comparison between
different coating methods, we show that spray coating on Si substrate and SS
mesh can repel lower surface tension liquids than spin coating on Si substrates
due to formation of half spherical micro-particles on the spray coated
substrates which is confirmed by FESEM images. Subsequently, superoleophobic
surfaces changes its super repellent property to complete wetting of any
liquids under UV illumination by decomposing the FDTS molecules via photo
catalytic property of titania particles. The superoleophobic property was
regained by annealing followed by grafting of FDTS on the UV treated surface
and the total process is repeatable over number of cycles.
