"AZO" compounds are highly sensitive to UV light and undergo a orientational change. using these compounds wettability of the surface can be easily tuned. 

Semiconductor materials such as TiO2, ZnO can also be used for such purpose.

for more detail check this link

http://www.sciencedirect.com/science/article/pii/S0032386114004108

hope this will help you.

Please check this article

Light-Responsive Block Copolymers from Macromolecular Rapid Communications