UV-driven reversible switching of a polystyrene/titania nanocomposite coating between superhydrophobicity and superhydrophilicity.

Hydrophilic titania (TiO(2)) nanoparticles were dispersed in solutions of polystyrene (PS), and the suspensions were cast on glass surfaces. The effect of drying temperature on the hydrophobic character of PS/TiO(2) was investigated: the static water contact angle increased with the drying temperature, and the as-prepared coating could be adjusted from superhydrophilicity to superhydrophobicity just by controlling the drying temperature. Moreover, the superhydrophobic coating turning into a superhydrophilic one (CA < 5 degrees ) after UV illumination, which can be recovered through being heated.